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AS MUCH INFORMATION AS POSSIBLE. NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS.

TECRJICAL E3MORANDUU NO. 237

RIGID AIRSHIPS.*

Sy Friedrich Stahl.

In contrast with the nonrigid. airship, in the development

of which men of all. ciuilized c0untrie.s have,assisted, the Tigi.dl airship is exclusively the result of German genius- Its father

is Count Zeppelin. . Chronologically, the airship of David Schrvarz' was built first (in 1897), but Zeppe1in.I~.plans go back to the seventies, of

'-1 - the last century. The plans for the. construction of the ~chfitte- i I Lanz airship did not nature until after the Echterdinge disaster

Spurred on by German successes, the construction of rigid

I airships was also undertaken in foreign countries. The Spiess airship in France and the Vickers in Engla.nd, mere finished shortly before the war. Their performances and especially their small carrying capacity, did not encourage further production. During the war, hoaever, England succeeded in making ser- viceable airships, after spies of the Entente had obtainedprac-

tical experience in airship construction by working in German

. . airship yards and after Zeppelin airships had fallen into the

hands of the enemy through forced landings. . . The successes England gained with these airships, including

* From flFlug-Fielt;lt 1920, Nos. 24 & 25; 1921, Nos. 1-4 & 6-13...... -2- I ' the American trip of thi R 34, may properly be placed to the, credit of Germany. Performances equivalent to crossing the ocean had previously been accomplished under less faaorablp, conditiol?~. - 7-I -. I But little was knom of these performances by the outside world 5.n general; hence the indefinite and contradictory views which pre- vail regarding the development and efficiency of Germ~nairships. Idmy groundless prejudices were formed, which I hope to dispel- Before considering the development of the rigid airships in- dividually, I will here give a list of all the, Z (zeppelin) and S-L ( ~chfitte-~anz)airships, with their principal 'characteristics- - Serial Consi;,;;tion Natrne;y Owned No . 1 1

LZ 1 Manzell Zeppelin 2 3 After alterations Army Rudders r elnodeled I1 I Manzell I Zeppelin Army

,,,,,,ichshafen -- I ~jeppelin After alterations German Airship Navigation Coo Friedri chshaf en ( Deutschland Ersatz I1 .' I I II Army

After alterations I1 Friedrichshzf en Schwaben German Airship IJavi gat ion Co .

I Han sa German Airship Navigation Co .

11 L 1 Navy

I I Ersatz Z I Army

II . It z IV

Sachsen11 German Airship Navigation Co. 11 After '1enahening I1 a) ~eppeiinAirships (~ont.)

: Serial . Construction Named by Owned by i No. yard owner I I LZ18 .Friedri ch shaf en L 2 Navy I 19 II Ersatz Z I Army

II 20 II z v II II I I

I1 21 11 . z VI

22 II Z.VII II

I I 23 11 z VIII

24 11 L 3 Navy

25 Friedrichshaf en Z IX Army 26 Frankfurt a. M. Z XI1 II

27 Friedrichshafen L 4 Navy

28 I1 L 5 II

.II ZX . Army - 29 c 30 Pot sdam Z XI I1

31 Friedri ch shaf en L 6 Navy

32 I1 L 7 II

33 II L 8 11

34 Po t sdam LZ 34 Army

35 Friedrichshaf en LZ 35 II

- .. u 36 .L 9 a Navy

37 Pot sdam LZ 37 Army

38 Fri edrichshafen LZ 38 I1

39 II LZ 39 11 -5-

a) Zeppeli~,Airships (Corit. )

Serial Construction I Baraed by Owned by Eo . yard I otmer -- L Z 40 Friedrichshafen L 10 lUa.v y 41 Lo ementhal L 11 II 42 Pot sdam LZ 72 Army 43 Friedrichshaf en L! 12 Navy

44 Lo ewenthal LZ 74 % Army 45 Friedri chshaf en L 13 Navy

46 Lo ewenthal L 14 11 47 Fri edrichshaf en LZ 77 Army 48 Lo ewenthal L 15 Navy 49 Pot sdam LZ 79 Army 50 Fri edrichshaf en L 16 Navy 51 Loementnal LZ 81 Army

After lengthening I I 11 52 Loewent ha1 L 18 Navy 53 Fri edrichshaf en L 17 I I 54 II L 19 11 55 Pot sdam LZ 85 Army 0 56 II LZ 86 II After lengthening n II 57 Lo ewen thal LZ 87 ll After lengthening 11 I n 58 Pot sdam LZ 88 I I 59 After lengthening It I I -6-

a) zeppelin Airships (~ont.)

Serial Construction Xamed. by Owned by 1No. yard owner After lengthening It Lo ewenthal Navy 61 1 62 1 Friedrichshafen 20 t sdam Army I! I I

Lo ewenthal Ikvy 65 1 Friedrichshafen I Artny 66 1 Pot sdam I Wavy Lo ewenthal LZ 97 Army 67 I I I I Po t sdam L 24 I Navy Lo ewenthal 70 1 Pot sdam LZ 101 Army 71 1 I Lo ewenthal I L 31 I Navy Pot sdam I LZ 103 I Army 74 1 Friedrichshafen L 32 I Navy 75 Staaken 76 Friedrichshafen Po t sdam 77 1 I Lo ewen thal Navy ?* 1 I 79 1 Staaken I II 80 I Friedrichshaf en - 7 -

a) "Zeppelin Airships (Cont.)

Serial Construction Named by Owned by No. yard omler

Pot sdam LZ 111 Army Fri edr ichshaf en Navy Staaken Army Lo ewen thal I L 38 Staaken I L 45 Fri edri chshaf en Staaken Friedrichshaf en Staaken Lo ewenthal Army Fri edrichshaf en L 42 Navy

I1 11 . L 43 Lo ementhal L 44 Friedrichshaf en L 46

I I L 48 'Loewenthal I L 49 Friedrichshaf en Staaken

Friedrichshaf en Lo ewenthal

Friedrichshaf en a) Ze&kiin Airships (ddnt. ) ;e;?i 1 ~ons'".,tion Named by Owned by owner

L Z 103 Staaken L 56 Na,vy 104 I1 L 59 11 105 Fri edrichshaf en, L 58 I I 106 II L 61 II 107 Lo ewenthal L 62 I i 108 Staaken L 60 I1 109 I I L 64 I I 110 Friedrichshaf en L 63 I I

111 Lo ewenthal L 65 II 112 ~rikdrichshafen L 70 I I 113 II L 71 II -- 114 Lo ewenthal L 72

120 - Fri edri ch shaf en Bodensee German Airship Navigation Co

After lengthening I1 II 121 Nordst ern . n

lay. . -9-

a) ~ebpdinAirships (~ont. )

Serial Gas Fo- of Length Diameter Useful load No. of No Capacity cells at 0' engines and 760 mm cu-m. m. m - P. L Z 1 11300 17 128 11.65 -- 2 2 11300' 16 128 11:. 65 2700 2 3 11300 16 128 11.65 2700 2 12200 17 11.65 2700 2 12200 17 1 ii: 11.65 2700 2 4 15000 17 136 13.00 4500 2 5 15000 17 136 13-00 4500 2 6 15000 1 17 136 13.00 4500 2 16000 18 144 13.00 4000 3

7 19300 18 148 14.00 6500 3 - 8 19300 .I8 148 14.00 6500 3 9 16800 16 132 14.00 -- 3 17800 17 140 14.00 6000 3 10 17800 17 140 14.00 6000 3

11 18700 18 148 14.00 6200 3

12 17800 17 140 14.00 6000 3 13 18700 18 148 14.00 6200 3 14 22465 18 158 14.86 8 600 3 15 19500 16 142 14.86 7050 3 16 19500 16 142 14.86 7000 3 17 19500 16 140 14.86 7000 3 20870 17 148 14.86 7500 3 7.' - 18 27000 18 158 16.6 11000 4 19 19500 16 140 14-86 7000 3 a) Zep~elinAirships (~ont. ) I Serial - No Capa.city cells engines cu-m. m. - L z 20 ,19500 1- 6 3 20870 17 148 14.86 7400 3 20870 17 148 14.86 '75'30 3

22140 18 156 ' 1-4-85 8000 3 22 140 18 156 14.86 ,1 8000 ' 3 .- 22500 18 158 14-46 8700 3 22 500 18 158 14.86 3 25000 15 161.2 I 3 22 500 18 1 158 1 ..L 8700

22500 18 158 . 14.86 8700 3 3 22500 18 158 14-86 ' 8700 . 22500 18 158 14.86 8700 3 22500 18 158 14.86 8700 3 158 14.86 8700 3 22500 158 14.86 8700 3 22500 18 158 14.86 8700 3 22500 18 158 14.86 8700 3

25000 15 161.4 16-00 ' 10000 3 22500 18 158 14-86 8700 3 32 000 15 163.5 18.7 15000 4 25000 15 161.4 16.00 10000 3 32000 16 163.5 18.7 15000 4 32000 16 163-5 18.7 15000 4 I I Serial Gas No. of Length Diameter Useful Joad No. of No. Capacity cells at 0 .engines cu.m. m. .m- an4.760 rnm -T - LZ42 32000... 16 163.5 18.7 15000 4'

43 32000 16 , 163.8 18.7 15000 4 44 32000 16 163.5 18.7 15000 4 ' I 45 32000 I 16 163.5 18.7 15000 4

46 32000 16 1 163: 5 18.7 15000 I 4. 47 32000 16 163.5 18.7 15000 3 (2.10 HP) 1 (240 HP) 48 32000 16 163.5 18.7 15000 4 49 32000 16 163.5 18.7 1 15000 4 i 50 32000 16 1163 5 18.7 150CO 4 51 32000 16 163.5 18.7 15000 4 35800 18 178 a 5 18.7 17500 4 52 32000 16 163.5 1 18.7 15000 4 53 32000 16 1163.5 18.7 1 15000 4 i ! 54 32000 16 163.5 18.7 ,i 15000 4 !

55 32000 16 163.5 18.7 15000 ' 14

56 32000 16 163.5 18.7 15000 4 35800 18 178.5 18.7 17500 4 I 57 32000 16 163.5 18.7 15000 .4 35800 18 . 178.5 18.7 17500 4

58 32000 16 163.5 18-7 15000 4 35800 18 178.5 18.7 17500 4

59 35800 18 178.5 18.7 17500 4. 60 32000 16 163.5 18.7 15000 4 35800 18 178.5 18.7 17500 4 61 / 35800 18 178.5 18-7 17500 4 a,) ~e~~k1i.nAirships (Cont. )

No. of Length Diameter Useful load No. of cells 2t o0 I engines m. m.

23.9

18.7 18.7 18.7

18.7 '

18.7 18.7 18.7

18.7 18.7

23.9

18.7

23.9

18.7

23.9

23.9 18.7

23.9

23.9 a) Zep~elinAif ships (~ont.)

Serial Ga s No . Capac i ty CU-M. and 760. mm 32000-32500 , Serial Gas No. of I Length Diameter Useful Joad No. of No. Capacity cells( at 0 engines cu.m. m. m. andkx60- mm

- L Z 107 56000. . 23.9 40000 5 l4 196*5 108 56000 I 23.9 40000 5 l4 I lg605 109 55000 14 ! 196.5 23,9 40000..... 5 110 56000 14 196.5 23.9 40000 5 C 111 56000 14 196.5 23.9 40000 5 112 68150 15 226.5 23.9 44000 7 113 68150 15 226.5 23.9 44000 7

114 68150 15 226.5 23.9 44000 ' 7

120 20000 12 120.8 18.7 10000 4 22560 12 130.0 18.7 11500 4 22560 12 130.0 18.7 11500 4 - 15 -

a)zeppelin Airships (Cont . )

Serial HP per Total Speed in Date of In service No. engine HP m/sec first till flight

29 8 '7/2/00 Spring, 1901. 2 I 170 11 11/30/05 1/17/06 3 85 170 11 i0/9/06 100 200 12.2 -- -- 100 200 15 -- Autumn, 1913 I 4 100 j 200 12.5 6/20/08 5 100 1 200 12.5 5/26/09 i i 6 115 ! 230 13 8/25/09 2 at 115 370 15-5 -- / " 140 11 7 1 120 360 16 6/19/10 : 8 1 120 360 1 16 3/30/11 9 140 420 21.7 10/2/11 140 420 21 -- 10 140 42 0 21 6/26/11 11 140 420 21 2/14/12 Autumn, 1915. 12 140 420 - 21 4/25/12 Summer, 1914. 13 165 49 5 21 7/30/12 Summer, 1916. 14 165 49 5 21.2 10/7/12 15 1 165 495 20.5 1/16/13 49 5 20.9 3/14/13 Autumn, 1916 l617 I 165 495 21 5/3/13 --

165 - 495 20 -- I Autumn, 1916. 18 165 660 21 .9/9/13 19 165 495 20.4 6/6/13 Serial HP per Total Speed in Date of In service 30 . engine HP first till m/sec. flight L 1, 20 165 495 26: 5 7/8/13 1 8/27/14 165 -- . 49..- 5 20.0' 8/27/14 ','7 ,.. . , L -, *. I 21 165 495 20.3 11/10/13 I 8/6/14 22 175 52 5 20.5 1/5/14 1 8/23/14 I 23 175 52 5 20.2 2/21/14 I 8/23/14 24 210 630 1 21.5 5/11/14 2/17/15 25 210 630 21.4 7/29/14 10/8/14 26 210 630 22.1 12/14/14 8/8/17

27 . 210 630 21.5 8/28/13 2/17/15 28 210 630 21.5 9/22/13 8/6/15 29 210 630 22.0 10/13/14 3/21/15 30 210 630 22.0 11/11/14 5/20/15

31 210 a 630 22.0 11/3/14 9/19/16 32 210 630 22.0 11/20/14, 5/4/16 33 210 630 22.0 12/17/14 3/5/15

34 210 630 22.0 ' 1/6/15 5/21/15 35 210 630 22.0 1/11/1.5 4/13/15 36 210 630 22.0 3/8/15 9/16/16 37 210 630 22.0 2/28/15 6/7/15

38 210 840 25.0 4/3/15 6/7/15 39 210 630 21.5 4/24/15 12/18/15

40 210 840 25.0 5/13/15 9/3/15, 41 210 840 25.0 1 6/7/15 Apr . ,1917. a) m~elindirshios (~ont. )

Serial HP per Total Speed in Date of GeGC- No. engine HP first till m/sec. flight -- L Z 4.2 210 840 1 25 6/15/15 2/16/17 25 6/21/15 8/10/15 43 i 210 840 44 210 1 840 25 7/8/15 10/8/15 45 210 840 25 7/23/15 Apr.,1917. 46 210 840 25 8/9/15 July, 1919.

. .-< .;24at 210 870 25 8/24/15 2/21/16 1 " 240 1 48 240 1 960. 25 9/9/15 4/1/16 I I 49 210 i 8 40 25 i 8/2/15 1/30/16 5o 240 I 960 , 25 9/23/15 i1 10/19/17 I I 51 240 960 25 10/7/15 / 9/27/16 .. 240 960 25 I 960 25 11/3/15 1 11/17/15 52 240 I 53 , 10/20/15 12/28/16 240 960 I 25 541 240 I1 960 25 11/27/15 2/2/16. . I 5b I+ 210 1 840' 25 9/12/15 5/5/16 56 210 , 840 25 i 10/10/15 9/4/16 25 210 I 840 i 57 240 1 960 25 ' 12/6/15 7/28/17 240 960 25 58 210 840 25 1 11/14/15 9/15/17 240 960 25 5/3/16 59 240 960 25 12/21/15 11/7/16 60 240 960 25 1/1/16 240 960 25 I ~ -- -- - Serial y~- per Total I Speed in Date c~f In service No. engine fi~st till flight

m;rc. 11/28/16 1 Summer, 1920. Surmer, 1917. il , II

5/14/17 2/22/16 8/22/17 7/5/17 August, 1917. 12/28/16, Sept., 1917. 10/2/16 August, 1917.

9/24/16 . Suminer , 1920. 9/24/16 July, 191'7.

11/28/16. . . July, 1919..

Summer, 1918. , 8/10/17 2/7/17

10/8/20 - 19 -

a) ',Zepwe1in- Airships (con%.) -- Serial HP per I Total Speed in Date cf In service TTn No. ecgine i &a T rn/sec . first till I flight

L Z 84 240. ! 1440 28 11/22/16 12/23/16 10;/20/17 85 ; li40 28 2/3/'1?:- 86 240 1440 28 12/11/16 3/17{17 I 87 240 1 1440 28 5/1/17 1/5/18 . . 28 1/3/17 6/17/17 88 . . 240 lsrO .89 240 ! 1440 28 6/9/17 . 10/2~/17 1/31/17 90 240 1440 .28 . . ..

. 91 240 1200 27 2/21/17 July, 1919. 92 240 1200 27 3/6/1.7 6/14/17

93 . ' 240 1200 2 7 4/1/17 10/20/17 94' 240 1200 27 4/24/17 1/5/18 95 240 1200 29.5 5/22/17 6/17/17 96 240 1200 29.5 5/13/17 10/20/17 97 240 1200 29.5 7/6/17 1/5/18 98 2 40 1200 29.5 7/4/17 August, 1919.

99 . 240 1200 29.5, . 8/13/17 7/19/18 100 2 40 1200 30; 0 8/18/17 8/11/18 101 2 40 1200 30.0 9/1/17 10/20/17

102 2 40 1200 28.0 9/26/17 10/7/17 . .

103 ' 240 . 1200 30.0 9/24/i7 August, 1919. . 104 . 240 i200 28.0 10/10/17 4/7/18 105 . 290 1450 32.0 10/29/17 1/5/18 . . aj :Zk3~elinAirships ( Conid- ) - Serial HP per To ta?. Speed in Date of In service No engine Xi? m/sec. first ti 11 flight . . . . .-- - ', Z 106 32 12/12/17 8/29/18 290 lC50 107 290 I 1450 32 1/19/18 5/10/18

108 290 1450. . 32 12/i8/17 7/19/18 109 290 1 1450 32 3/11./18. 7/22/20 I 110 290 1 1450 32 3/4/18 July, 1919,. . July, 1919. 111 ' 290 1450 32 4/17/18

112 , 290 2030 36 7/',/18 8/5/18 113 290 2030 36 7/23/18 7/1/20 114 290 2030 36 7/9/20

120 240 9 60 37 I 8/20/19 I 121 240 960 1 1 i a) Zep~elinAir shijs (Cont. ) R~iarks.

L Z 1 Dismantled in construction ysrd.

2 gestroyed by storm after forced laanding at Kiesslegg (~lggu). 3 Obsolete; dls~antledin Metz hangar. 4 Forced to land at Echterdingen and afterward buzned. 5 Forced to land at Wei!.burg; carried away and wrecked by storm.

6 Destroyed by fire in Baden-00s hangar. , 7 Wrecked at Wellendorf (~eutoburger~ores'c). 8 Destroyed while being brought out of ~&ssel.dorfhangax.

9 Obsolete; dismantled in Gotha hangar. 10 Destroyed by fire at Dusselaorf. 11 Destroyed while being brought into Lej.gnitz hailgar. 12 Obsolete; dismantled in Metz hangar. 13 Obsolete; dismantled in Johannisthal hanger. 14 Wrecked at Hellgoland. 15 Destroyed by starm at Karlsmhe after foxed landing. 16 Obsolete; dismantled in ~fiterborghacgar. 17 Obsolete; dismantled in ~ifirenhan~r. 18 Caught fire during flight and destroyed at Joha.nnistha1. 19 Wrecked at ~iedenhofenafter forced landing.

20 Hit by gunfire and wrecked at Lipoviec (14laya). 21 Hit by gunfire over ~8ttich2nd wrecked at Coiogne. 22 Hit by. gunfire and wrecked at St. Quirin on observation flight. a) Zeppelln Airships (Cont - ) . Remarks .

!!it by gunfire and wrecked at Badonvillers on observation flight. Wrecked on coast of ~an6,after failure of a.11 its engine s. Destroyed by English aviators in ~fisseldoi-f.haxlgar. Dismantled In ~ater-aorhangar in consequence of the discon-kirluance of the Amy airship sexvice. Driven by storm to Denmark and wrecked at Borsnose.

Hit by gunfire a.hd vrecked. at 1Jlit.a~. -- . Hli by gilnfire in raid on Paris'and wrecked at C.Z .*'--..,-; -'-. St. Quentin. Wrecked and burned in removing from Posen hangar.

Burned in i?uhl sbb t t el hangar. Shot down at Horn's Reef on reconnoitering trip. Shot domn and wrecked at Tirler~ont. Hit by gunfire in raid on 'Xov-no; forced to land in East ?russia,; carried aEay by wind and burned. !lit by gunfire and wrecked at Thielt in raid on Poperinghe. Burned in 'hhlsb~ttel hangdr . Shot down by aviators at Ghent, after raid on Calais. Destroyed in ~dssel-~verehangar by ~ngli-shaviators. Hit by gunfire in raid on Kovno and wrecked at Luck. Struck by lightning and fell in flames near Cuxhaven. Obsolete; dismantled in Hague hangar. Dismantled in ~fiterborghangar in consequence of dis-. ' continuance of Army airship service. a) Zep~elinAir shins ai on,)

L Z 43 Hit in raid .on England, lar~dedand 'ov..rned at Ostend. 44 TJrecked in Felgium by rulnning into a moilnta.in.

45 Obsolete; d.ismntled in Hague hangar. 46 Destrcyed in Yordholz hangax. 47 Shot dovn at Revigoy.

48 Forced. do-wn and sank at mouth of the Thames, after raid on England.

49 Hit by gunfire in raid on Paris and mrecked at Ath. 50 Destroyed in Nordholz from land.iag too nard. 51 Hit by gunfire in raid oil l3uka~es-k;fo~ced to land and wrecked at T~ov~o-

52 Destroyed by fire i~ Tanclera hangss. 53 Destroyed by fire in .Tondern hangar. 54 Fell into North Sea. 55 Hit by gunfire in raid on Saloniki and ~ireckedat Wardar.

56 Vrecked at Teriesvar by landing. .. too hard. 57 Disriantled in ~fiterborghangar in consequeilce of discontinuance of Amy airship service. 58 Adopted by Navy as experimental airship L 25; became . obsoleteandr;iasdismantled inPotsda,mhangar. 59 Was carried away and mrecked at Stavanger, as a result of engine trouble after raid on England.

60 Torn from its moorings at Yittm-dnd by 2 storm and carried to sea unmanned.

61 Shot dom near Lomestof t on coast of ' England. 62 Dismantled in Seerappen hangar. a) Zeppetir! Airsh&e (C~nt.-) Remarks.

nisnantled ir, Trier hangar, due to discontim.ance of Army air~hipservice. Shot down by tarpedo boats near Tersckelling. Hit by galfire ~hileflyiag over Champagne front and nrecked alt Namur. Shot donn by torpsvdo boats near H9rnBs Rcef. Dismhntled in 2;-terbcrg hangar, d;le to discontinuance of Army airship service.

' ., Disxantled. in SchneS.ciemiihl >angar, d.xe 'GO discontinu- axe of Arm?- airship service. Destroyed by fire in Tondern hsnsar . 70 Building discontinued to aake reom for bvilding airships of 55000 a.m. (1,942,325 cu.ft.) %as capacity. 71 Dismantled in ~Gterborghangnrdue to Ciscontinuance of Ariny airship service. 72 Shot down in raid on London. 73 Disma3tled in ~8nigsber~hangar, due tc discontixu.ance of Army airship service. 74 Shot down in raid on ond don. 75 Taken apart in Seddin hangar to be reassezbled in Japan. 75 Hit by gunfire at Srentwood, England, forced to iand and thsre dismantled.

77 . Dismantled ir! aar~stad-i;hangar, due to discontinumce of Army airship service. 78 Shot down by English aviators atScaarborough on the coast of England. 79 Destroyed in Nordholz hangar. 80 Obsolete; dismantled in Jfiter~org.,. hangar. a) Zep~elinAirships (~ont,) Remarks .

L Z 81 Dismantled in Dresden hangar, due to disc;onlin~anceof Army airship service. 82 Wrecked in fog at Rethem (~ller). 83 Was flown from Seddin to Mauberge and delivered to France. 84 Wrecked at Seemuppen, Russia. 85 Wrecked in Saone valley, after raid on England. 86 Shot down at Compeigne. 87 D3stroyed by explosion and fire in Ahlhorn hangar. 88 Wrecked at Neuenwaide (~eestednde). 89 Wrecked in Svitzetlland after raid on England and landing at Xontigny le Roi, France* 90 Soon to be flown from ~eera~~en'nea~r~Gni~sber~, to Rome, and 'curned over to I talian Government. 91 Destroyed in Mordi-1012 ha,ngar. 92 Shot down over North Sea by English fleet. 93 Snot down in France after raid on Englar~d. 94 Destroyed by explosion in Anl-horn hang~~r. 95 Shot down at Ipswich. 96 Carried away and vreclced at Bouchon les Bains, France, after raid on England. 97 Destroyed by fire in Ahlhorn hangar. 98 Destroyed in Wittmund bangar. 99 Destroyed by English aviators in Tondern hangar. 100 'Shot down near Terschelling. 101 Bit by gunfire in raid on England and wrecked at Tiefenort (Werra). a) Zemelin Airships (~ont-. ) Remarks.

L Z 102 Destroyed by fire iil front of 2fiterborg kar,gaz. 103 Destroyed in Vittmnd hangar. 1.04 Fdl in flames over Otranto Strait (cause unknomjg

105 Destroygd by explosion in Ahlhorn hengar. 106 Flom from Wittniilnd to nome and delivered to the 1 talian Zoverment. 107 Fell while flyin? over Eeli$pland. 108 Destroyed by English avlators in TcnZezn hangar.

109 Floojn. from Ahlkorn to Pulham and deli-jer ed to the Eritish Government. 110 Destroyed in Nordholz ha-nga-r. 111 Destroyed in Nordh~lzhangar. 112 Shot domnear Boston.

113 . Flown from Ahlhorn to Pulhanl and delivered to the British Government. 114 Flown from Loewenthal to Edauberse a-nd d elivered to the French ,Soverment. 115-119 Not built. 120 Not operated after lengthening, because of prohibi- t ion by Entente. 121 Not operated because of prohibiticn by Entente. b) SCFWTTE-LANZ AI3SKIFS.

A - serial 1 Constructionyard- ' Warned by Omned by. ilo . 1 omer --- SL 1 meinail SL 1 S.L. Airship Co.

2 ' Rheinau 2 Army After 1zngthening 1 A riny

3 Rheinau 3 Navy

. . 4 Sandhof en 4 Navy I I 5 Darmstadt 5 Army 6 Leipzig i 6 Navy 7 Rheinau I 7 Army 8 Leipzig 8 Navy 9 Leipzig 9 Navy

10 . R'n e i nau 10 Army 11 Leipzig i 11 Army 12 Zeesen 12 Navy

13 Leipzig 13 Army

14 Rheinau 14 Navy .

15 Rheinau 15 Army

16 Leipzig E 9 Army

17 Seesen 10 Army

18 Leipzig 11 Army

19 Leipzig 12 Army 20 Rheinau SL 20 Navy

a 21 Zeesen F 2 Army

Rh einau SL 22 Navy 22 I b) Schutte-Lanz .Iti.rships ('~ont.)

Serial Ges ~b . of ~ength/ Diamet el. ( Useful ioad I I

11 38780 19 174 20.1 21000. , 4 12 38780 20.1 20800 4 13- 38780 :: ::: 20.1 20000 4 14 38789 . 19 1 174 20.1 20500 4 19' 1174 20.1 20500 4 15 38780 I 20500 4 ' 16 38780 19 1 174 20.1 17 38780 19 174 20.1 20500 4

18 38780 19 174 20.1 --, 4.

. 19 38780 19 174 20.1 -- 4

' 35300 5 20 56000 20 , 198.3 22.92 21 56000 20 198.3 22.92 35400 5 22 56000 20 198.3 22.92 -- 5 b) ~ehutte-fjanz~irships (~ont- ) J I Serial HP per Total Speed in i Date of In service No. engine HP . m/sec. 1 first till 1 flight - I SL 1 240 'i 480 1 19.7 1 //l 7/17/13 2 180 / iao 1 24.5 I z/za/ln . 210 840 -- i -- 1/;O/16 i I 3 210 840 23.5 2/4/15 5/1/16 I I iI 4 210 840 1 23.6 i 4/25/15 12/15/15 i I I 5 210 ' 840 . 23.1 i 6//15; 7/5/15 ! 6. 210 840 25.8 ! 9/19115 11/18/15 i 7 210 840 25.0 ! 9/3/15 5/6/17 8 240 9 60 25.8 3/30/16 11/20/17 i i 9 240 9EO 25.8 ! 5/24/16 3/30/17 10 240 960 25.0 I, ;/17/16 7/28/16 11 240 960 25.5. j 8/2/16 9/3/16 I 12 1 2 40 9EO I 24-08 11/9/16 12/28/16 i 13 ! 240 960 25.0 10/19/16 1 2/8/17 ' I 14 1 240 960 25.0 8/23/16 1 5/11/17 i i 15 1 240 960 25.0 11/9/16 1 Summer, 1317. i ! 240 960 25.0 1/18/17 1 SUIIWI~T,1917- -I6 1 17 240 960 -25.0 1 3/22/17 Summer, 1917. 18 240 960 -- 2/8/17 I -- i -- 19 240' 9 60 -- -- iI 20 240 1200 28.5 9/10/17 21 2 40 1200 11/26/17' 1 February, 1918. 22 240 1200 28.. 5 6/5/18 June, 1920. I 1 i 3) Schutte Lark2 r"ii.rsbigs (con&) Remarks.

Destroyed by storm at Erpel (~chneidefi16.hl). Vrecked by storm at Luckenwalde. Wrecked in the Bzltic Sea. Destroyed by storm in Seddin hangar. Forced to land at. Giessen, torn loose and wrecked by storm. Fell in flames near Seddin (~tolp). Dismantled in ~Cterbor~hangar, due to discontinuance of Army airship service. Dismantled in Seddin hanga2. Fell in flames into Baltic Sea west of Pillau. Disappeared over Black Sea. Shot down in raid on London. Wrecked 'at Ahlhorn. Destroyed by fire at Leipzig.

Damaged by landing too hard in Wainodea . (~urland) and dismantled. Dismantled in Sandhofen hangar, due to dkscontinuance of Army airship service. Dismantled in Opich hangar mear Cologne, due to discontinuance of Army airship service. Dismantled in Allenstein hangar, due to discontinuance of Army airship service. Destroyed by fire in Leipzig hangar, before completion. Not completed, on account of the damage to the Leipzig construction yard by fire of February 8, 1917.

Destroyed by flames in Ahlhorn hangar- - 31 -

b) Schutte-Lanz Airships (~ont. ) Remarks.

S L 21 Dismantled in Geesen constructio;~yard, due to discontinuance of Army airship service.

22 ' Dismantled in ~6terbor~hangar.

Unfortunately, it has not al~aysbeen ~ossibletc obtain absolutely relihble data on each individual airship, especially on those built during the war. Some of the data on speed and useful load are either lacking or variously re?orted. Since it is difficult to determine speed and especially useful load accurately, small differences in the computation are all .the more noticeable in a tabulation of this kind. In the computation of t3e useful load, the temperature of the gas and of the air, atmospheric pressure and specific meight of the gas can be accurately determined, but not always the relative humidity of the air. In "Mot~rwagen,~~1919, No. 22, Prof. C. Ehrhardt, iecturer on aviation at the Darmstadt Technical High School, has discussed in detail the difficulties of determining accurately the gas capacity. Moreover, views vary as to just what constitutes the useful load and the dead load. The determination of the speed is likewise subject to various influences which cannot be considered in such a tabulation. Gusty weather and the static condition-:of the airship exert considerable influence. Lastly, the resistance or drag due to the radio anten- nae and the crew on the platform; the condition of the emelope and. the revolution speed of the engine play an important role. The maxlmm speed is of no practical value, the determination of . the "cruising speeci" being mch more important. The latter is the speed at normal engine power with the emplo-pent of radio apparatus, armanent, etc.

Scnrrarz Airship-.

In 1893, David ~ch~arzbuilt a rigid aluminum airship in St. Petersburg (~etrograd). It could not.be used, however, because the inside stay wires were broken by th'e gas pressure during in- flat5on. In 1895-1897, he built in Berlin a new airship 47.5 meters

(155.84 feet) long and 13.5 meters (44.29 feet) in diameter. It - had the shape of a projectile pointed in front and 'rounded at the rear end. The frame consisted of 12 main transverses, 16 main longitudinal lattice-girders and numerous intermediate transverses and longitudinals. The transverses were braced radially inside. The air-tight envelope, inclosing the whole undivided space of 1 3700 cu-m- (130,666 cu.ft. ) was made of 2 mi. (.0?87 in. ) sheet

aluminum- The car mas rigidly attached to the hull by lattice- girders and braced by mires extending to the ends of the hull.

. The single Daimler engine developed 12 F9 at 480 R-P.B. The gaso- line consumption mas 0.42 kg. ( .926 1b.) per HP-hour. The airship had three propellers, two of which were mounted on brackets attached to the hull and-had a dianeter of 2 meters (6.56 feet). The third had a diameter of 2-75 meters (9*022 feet) and. was mounted between the hull and the car on a shaft capable of being turned about a vertical axis soas to serve for steering, as the airship - had no rudder. All the propellers mere drivgn by means of belts. Another propeller, designed to be used helicopter-fashion, did not materialize. At the suggestion of Captain Bartsch von Sigsfeld, the air was driven out of the hull by inflating cloth bags previously introduced into the hull. These bags were then ripped and remo$ed throua the bottom of the hull. On the first trial trip, November 3, 1897, the airship rose,

as a captive balloon, in a wind of 7.5 meters (24.61 feet) per sec-

- ond. During the immediately follovfing flight, the driving-belts soon slipped off their pulleys and the rudderless airship, with on-

ly one.man on board, was carried away by the wind and compelled to attempt a forced landing. The airship was so badly damaged in landing and by the further effect of the wind that it had to be broken up- Since then no metal airship has been built. The project of the Hungarian steel airship was never carried out.

Zeppelin Airships up to Be~nningof War.

Count Zeppelin did not allow himself to be dissuaded by the fa-ilure of the Schwarz airship from his long-conceived plan to build a rigid airship of what .were then considered giant dimensions- In 1898, after he h2.d succeeded in founding the llGesellschaft zur ~8rderungder L~ftschiffahrt:!(~ssociation for the Promotion of Airship Flight), and had secured the necessary funds, the construction of an airship and of a hangar in Manzell was beg~n- In 1887, in a memorial to King Karl of ~Grtemberg,Count Zeppelin had already outlined the great tasks, both military and economic to be performed by airships; nainely: scouting and raiding in war; long-di stance transportation and exploration of unknotm

regions in times of peace. . . These ends could only be accomplished by means of several pow-

erful engines for attaining a high speed and by increasing the lifting power, so as to be able to carry sufficient fuel for long trips, in addition to a considerable nuaber of persons and bombs. - Count Zeppelin realized from the first that .these conditions

could only be fulfilled by large airships. In contradistinction to the builders of small nonrigid airships (who mere really only endeavoring to solve the problem of making free balloons dirkgi- ble), he kept constantly in mind the development of the large airship. Zeppelin's significance resides in the fact that he abandoned the old tradition of Meusnier (descended from 1784) and went his om way. In doing thus, he set mch at stake. Often his life's work seemed annihilated and the development of the rigid airship hopel-ess, but he always managed to tide over his misfortunes and finally attained his goal. His views have been vindicated- Rigid airships have been successfully employed for raiding and scanting in war and have long since demonstrated their ability as a means of transportation between distant regions, as evidenced by the trip of the L 59 to - Africa and back and the 100 hour voyage of the LZ 120. Nothing nom

stands in the way of their economic util-ization. The first Zeppelin airship had the shape of a cylinder pointed at both ends. It Tas 128 meters (419.95 feet) long and 11.65 meters (38.22 feet) in diameter. Each transverse frame was a regllar 24-sided polygon. The longitudina,l framevork consisted of aluminum lattice-girders. For increasing the strength and rigidity, tne transverses mere braced inside by mires and divided the hull into 17 compartments, each containing a, fabric ps bag- The whole hull nas covered with water-tight cotton fabric. Underneath the hul.1, there mere two cars rigidly suspended and

- provided each with a 14.5 HP-Daimler engine. Each engine drove two four-bladed aluminum propellers (one attached to either side of hull) of only 1.1 meter (3.61 feet) diameter, by means of bevel gears and long oblique tubular shaffs. By tbe installation of a reversing gear, it was also possible to drive the p~opellersbackward. The function of a lludder mere performed by four vertical 'steering surfaces, two in front above and below and one on either side of stern- For ascending or descending, the airship was trimmed by means of a sliding weight of about 100 kg (328.08 lb) . b. The first flight mas made in the evening of July 2, 1900, with five persons on board. The flight had to be interrupted after 18 minutes, due to failure of the rudders. The alighting on Lake Con- stance.took place smoo.thly, however.. It; afterwards encountered a ;; pile and s~ffered sone damage. Distortions of the framework during flight rendered the removal of the gas necessary. Various i-mprovements were then undertaken. First of all, the walk-may, which had only been suspended on mire cables under the llull, was rigidly attached to the frameoork, thus considerably str elzgthening the latter. The lateral steering surfaces mere &is- carded and were replaced by several vertical surfaces under the hull. Since the sliding weight had not p~ovedsatisfactory, a steering surface with a horizontal zxis mas' installed in front of the forward car. The sliding weight was at first retained, however, though differently arranged. The changes were completed by the end of September, 1900, 'out the airship suffered further injuries in its hangar by the tearing of suspension devices. It took till the middle of October to repair 'these dama,ges. The second flight took place October 17, and lasted one hour and twenty minutes, the new arrangrments~proving successful. ITG speed ineasurements mere undertaken, homever, due to failure of the rudders.

A.third flight was made October 24, b-fit lasted only 24 minuJ6es, since the frame again bent upward in the middle. The airship had developed a speed of about eight meters per second- The funds supplied Count Zeppelin by the tlGesellschaft zur ~drderungder Luftschiffahrtn had now given out, so that furthe;: flights had to -be foregone. The association disbanded and Count Zeppelin acquired the airship, hangar and accessories as his om property, in the hope-of being able to resume the experiments later. What had been acconpliehed? Count. Zeppelin had, in spite of

211 the docbts of aviato~sand scientists, built a ~igidairship and made several flights with it. It differed from pre'ious air- . ships in: 1. Size; 2. Alur~in7-lmframe;

3. Division of gas space into ce1l.s;

4. Independence of pover plants of one another;

5- Rigid wispension of cars; 6. Attachment of propeller bra~ketsto hu2.l;

7. InJcroduction of elevator; 8. Introduction of walk-way. The rigid frame gave the airship a pernsne~tshape, which

could only be obtained in a nonrigid airship by internal pressure. In the first frame, hooever, the top girders meye not strong enough. Count Zeppelin ~ightljrput great faith in the -division of the gas space. While a nonrigid airship, in the event oi a tear, could no longer be kept in the air, an injury to one gas cell of a rigid airship resulted only in a decrease in the lift xhich could usually

be offset by releasing ballast. The gas cells were all p~ovided with safety valves, through which the gas escaped when the internal pressure became excessive from altitude or heat. In order to diminish the lift under certain circumstances, some of the cells were

provided with valves which could be opened at trill- The fabrlc use$. for the cells was not sufficiently gas-tight, so that the already small lift constantly. decreaseti.- The independence of the power plants had decided advaatages. In case of the failure of sorile part, like the driving gear or the propeller, the airship was not thereby deprived of its entire engine power, 'out could proceed with the aid of the other engine. The rigid suspension of the cars and the fixed distance between cars and hull enabled the installation of propellers on the latter. They were located at the so-called ":center of drag," at which, according to the then preoalent view, the propellers were most efficient. This suspension method naturally had its disad- vantages, since, in hard landings, the shock was transmitted to the hull and driving gear, which it vas liable to damage. The elevator experiments were encouraging. The altitude control by means of the sliding weight worked too slow. The walk-way, which was still very crude and led only from one car to the other, enabled transfer of weight between the cars and the in'spection of certain parts during flight. The frame was not built strong enough to make the hull perfectly rigid. Thus certain principles had been established which were tvorthy of further development. The general efficiency of the airship was, nevertheless, aery unsatisfactory. Its small carrying capacity was out of all proportion to its size and its small speed was insuffic- ient to make headmay against even a very moderate wind. Consequent- ly, no one was found to furnish the funds necessary for the completion of his) task. Even the "Verein deutscher Ingenisure" (society of German ~ngineers)which had had a large share in founding the llGesellschaft zur i?$rde&ng der Luftschiffahrt, refused to aid himo In the still uncertain evolu.tion of the airship, %he gre&ter value was generally placed on the small nonrigid type which, in case it were unable to proceed by its om power, could be packed up and transported by rail or wagon- It mas considered that no great success could. be obtained with the engines then in use. All the Count's attempts to obtain funds, by advertising in thz press, failed and he was compelled to dismantle both airship and hangar and sell them as junk. Any one else mould have given up, after these disappointments, but Count Zeppelin did not despair of the future. With tine same energy, which resulted in the building of his first airship, he continued to strive to awaken interest in the building of another. He found an ardent supporter in the person of the King of drtem- berg. A lottery, instituted in ~hrtembergat hissuggestion, yield- ed a large sum. Other Gernan states par%icipated in this lottery or made small donations. Factories like those of Eveking, Daimler and Riedinger announced their readiness to place aluminum, engines and balloon fabric for further experiments at his df sposal, so that the preparations for building the second airship mere begun in 1904. The construction of the LZ 2 was under the technical supervis- ion of the engineer ~hr,who had taken the place of ~abler. The

LZ 2 mas completed in 1905 and had the same dimensions as the LZ 1, but differed considerably from its prsdecessor~instructure. In place of the lattice-girders, stronger triangular girders nere employed; its cross-section had only 16 sides instead of 24; and it had 16 gas cells instead of 17. The weak engines -+JereYe-

$~a.ced by stronger oiles o? 85 ZiP, each of which drove 2 tnree- bladed propellers of 3 meters (9.84 feet) diameter- The malk-nay was raised from 0-8 m (2.62 ft) to 2 m (6.56 ft) and materj-ally stiffened the hull by its stronger constructioq. The sliding weigllt was left off and ths rudde~sand elevator improved. The first ascent vas to take place NovemSer 30, 1905, but it did not materialize, since a cabJe becaae entangled with the airship and brought it dom again onto the lake, aa.maging the rudders which had been installed in front of the forward car. Its first and only flight took place January 17, 1906. The airship obeyed its rudder perfectly, but at Its flight altit~de. of 400 meters, could make no headway against the ever increasing mind and finally, when one engine had to be -stopped on account.. . of excessive heating, was siowly carried tonard A~&u. Soon the other engine failed and the pilot, Lieu.t. Von Krogh, was compelled to land the airship like a free balloon.

A smooth landicg was made in a meedow near Kisslegg in ~l~gu, but the airship was driven sidenise by the gr;ro;nd wind and finally came to a stop with its stern hanging in a tree. The damages being comparatively slight, it was hoped to prepare the airship for re- newing its flight after the arrival of men a~dgas f~omManzell. The airship, however, was so seriously damsged by a storm ahich arose in the night that it had to be dismantled.

Thus the question of the rigid airship seemed to have been dis- posed of once for all. The single short flight of the LZ 2 had in- . seed shown that Count Zeppelin had gotten further on the rig>+, track. The more powerful engines had pr~ducedthe greater speed of 10 in (32.8 ft) per second. The strecgth of the frane and the de3endable enctioning bf the rudders inspired conf ids~ice. Lastly, it had been possible to make the whole structure lighter and. thus increase the lift. The plblic, homevcr, pronounced judgnent only according to the apparent final result. The airship had nade only one flight and, after its first landing, had been discqantled. Any such accident would not have resdlted in tne total destruction of a nonrigid airship. P Still Count Zeppelin would not al1.0~himself to become dis- couraged. He could not; believe that the misfort~nesof the ei~gines' failing and the rising of a storm would fo~everexclude his airship from further development. And his faith in the future finally triumphed. Count Zeppelin contrived, in a very short time, to obtain the necessary money for building a third airship and ha& it finis3ed la.te in the autumn of 1996. This time no unlucky s'~a.rruled over I the airship. Both, flights, of October 9 and 10, proceeded satisfactorily, up to four hours' duration, and demonstrated the prac- ticability of Zeppelin' s ideas. The LZ 3 wzs constructed on the same plan as the LZ 2. The only innovation mas the four nearly horizontal stabilizing planes arranged in pairs on either side of the stern. This innovation, which was only reluctantly adopted, meant a long step forward. On both the forner airships there had been a disagreeable rolling motion during flight. After the addition of these lateral fins, the airship was quite stable with respect to its 1-ongitudin2.1 axis. Funds were l2,cking for continuing the expei-inen-ks, but further successes of the new airship mere not: long delayed. A new lottery was started and the governri~entbuilt a floating hangar on Lake Cons$ance near Manze!..l. Like the 1899 hangar, it was anchored in such a way that it always smng in the direction of the wind. This was in order to minlmize the chances of injury in bringing the airship in 2nd out of the hangar. For bringing out the airship, it was moored to the floating floor of the hangar, vhizh as towed out by a steam tug. During the building of the hangar, a fern a.lterations were made in the airship LZ 3. The walk-may, which had hitherto extended on-

ly from one car to the other, was extended both fore and aft. This made it possible to walk almost the whole length of the airship during flight. Extensive alterations mere made in the steering gear. The. rudders underneath the airship were removed and rrere replaced by box &dd.ers placed between the stabilizing planes at the stern. The elevators underneath xere removed and were replaced by sets of four elevators on either sicle both fore and aft. The floating hangar mas completed in the autumn of 1907, and the rebuilt LZ 3 mas transferred to it from its former stationary hangar. The trial flights were awaited in suspense. This time the government mas directly interested, having appropriated, in the spring of 1907, the sum of 500,000 marks for the Zeppelin experi- - 43 - ment s. The government required certain perforniances, however, as, for example, a 24-hour non-stop flight of at least 700 l;m (435 mi. ), a portion of it at an a,ltitude of 1.500 m (492.12 ft), to a previ-- ously specir'ied destination and return to Xa.nzell. Vould the airship be able to fulfill these conditions? Tech- nical experts probably felt the least conf iaent. Former flights had shovm horn the success of each one depended on circumstances- Could the engines stand tile endurance test? Was the crew sufficiently trained and v~elienough acquainted with the airship to undertake such a flight? the further narrative, me will see ho~far the airship mas at that time from being ~bleto fillfill such requir ements. On Septenber 24, 1907, the experiments began and proceeded in fine shape. Count Zeppelin exhibited his ai~shipto tns representatives of civil and military bodies in five flights - on September 2.4, 25, 26, 28 and 30. All the parts worked well and demon'strated the wisdom of the alterations. The new elevators mere an especial improvement. Only the functioning of the rirdders was not entirely satisfactory. On the 30th, a seven-hour flight vas made, covering a distance of about 350 kilometers, constituting the best endurance record made up to that time by any airship. No further attempt was made that year to accomplish the 24-hour flight. The commission sent by the government to observe the performances of the airship had to acknowledge its capabili- ties, but cou-ld not escape the conclusion that only under the most favorable conditions was there any possibility of the airship (of small carrying capacity) being able to succeed in the endurance test. Count Zeppelin then proposed to give up further experiments with the LZ 3 and to build a larger.:airs3i;w with gr.eater carrying capacity for undertaking the endurance flight. This plan was ap- pro~edin October, 1907, at a conference in Berlin of representatives of the mar department, the general army staff, the department of the interior, the treasury depar-tment and the department of edu-

cation. , After the "Reic'hstag" had made further appropriations, the construction of the LZ 4 nas begun. By assisting the second time, the government showed what a high value it set on the airship, both from the military and cultur- al points of view, and how determined it was to keep the lead Ger- many had obtained over other countries. All the more interest was aroused in the develoFrnei-it of the airship, because at this time experiments had been begun in Germany on the Parseval military airship and in France the development of the nonrigid airship mas making good progress.

The completion of the LZ 4 was delayed until June, 1908, be- '. cause the floating hangar containing the LZ 3 was considerably damaged by a storm in December, 1907. Repairs had to be awaited, because the LZ 4 was to make its trial flights from the same hangar. The LZ 4 began its trial flights June SO, 1908. With its greater gas capacity of 15000 cu.m., it had a coasiderably-greater carrying capacity than the LZ 3. The stronger engines of 105 HP each produced, moreover, an increase of 1.5 m/sec in speed. The cars were larger a.nd accor.modated. a larger number of perzons. At the middle of tile walk-way a passexger cabin was added. From this point a climbing shaft led to an observa5ion platform on top of the hull. - The rudder arrangement undervent the greatest variety of changes.. On the first flight, there mere botfi a bow and- a"':.:':i stern rudder. The bow rudder vias then removed and the old box rudders again installed betmeen the stabilizers. Since this arrangement was likewise unsuccessful, the small stern iviider mas replaced by a large oval rudder. This improved the lateral steering, but still left much to be desired as compared with the excellent vertical steering.

On July 1, 1908, Count Zeppelin made his famous 12-hour flight over %itzerland, which was carried out without accident and attracted much attention. For the fii-st time, the airship had flown a long na,y from its nome port and over rough country. Xuch useful experience was thus obtained. After the Ring and Queen of

mrtemberg had participated in a short flight on July 3, the LZ 4 was deflated, in order to begin the great flight with fresh gas. For this parpose, the airship ascendsd on July 14. It was planned to follow the course of the Rhine over Ba.sel, Strass'oui'g and Mannheim as far as Mainz and to make the.return. flight across

the interior over Stuttgart. At Constance, however, the trip had to be interrupted on account of damage to a radiator. On the following day the airship- was. again in condition and the attempt mas repeated, in spite of unfavorable weather. mile being brought out of the hangar, the airship hit against the nall of .the hangar al~ddamaged tine elel~ator.and propeller. Also one gas ceil was dam-

a%ed, rendering S.t &gain a.scessary to defla,te the airship. On August 4, the damages had heen repaired and the LZ 4 left Lake Constance early in the morning, cai-rying 12 persons, fuel for 24 hours and 600 kg (1322.76 lb) water ballast. After a smooth

. 11-hour flight over Schaffhausen, Basel, Strassburg, Speyer and Mannheim, it arrived north of Worms, mhere Count Zeppelin decided to make a lailding. One engine had stopped and the airship, which had lost mch gas, due to the heat of the sun and the high altitude, had become heavy. There mas no ba,llast left and the one remaining engine was not powerful enough to hold the altitude with the aid of the elevator.

A smooth landing v;a,s made at Altrhein near Oppenheim. After being repaired and lightened by the removal of spare parts and several persons, the airship ascended again at about 10: 30 p.m., flew over Mainz and then south~.erdover Mannheim, when the forvard engine stopped for the rest of the trip, due to the melting of a bushing. The LZ 4 proceeded slowly and reachzd t5e region of Stutt- gart on the morning of Al~gu-st5, w5ere another smooth landing mas made on solid ground near. Echterdinger,, after the airship could no longer make headway vith a single engine agalnst a freshening south wind. The airship mas moored after a makeshift manner and held by a zompzny of soldiers. In the afternoon a tenpest arose. -4 sudden gust struck the airship broadside arid tore it away from its mooring and the men holding it. After a short flight at a lorn altituae, it caught fire as it stluck the ground and' mas completely consuled. - 47 -

A common grief $ervaded the German people. Even foreigii couil- tries did pot with'noLd recognition of. what had thus far been acc9-m- plished. Everybody had followed this flight with interest - and no-,v the outcome! There was, however, one alleviating circumstance i-n this misfortune. Count Zeppelin was urrha-med. Ee, wi'th most of the crew, had left the airship and nas not even an eye witness of the catastrophe.

At first thought, it seemed that the life-xork of Count Zeppe- lin had gone for naight, since the government had conditioned its further supyorl on the outcome of this flight. But the German people jud.ged the matter irn~artid.ly. ?hey recognized the value of what Count Zeppelin had accomplished and knev horn to shorn their appreciation. They supplied hiin mith such abundant funds that he was able to carry out his plans on a large scale. T'n~isthe Echter- dingen disaster proved to be the d-ecisive turning point in the development of the Zeppelin alrship. Technical experts, however, interpreted the state of affairs differently. They reasoned from the fact that the airship had not completed the stipulz-ted endurance flight and. that under like conditions a nonrigid airship would not be given over to destruction. Count Zeppelin mas nov, hotqever, less dependent on the judgment of experts and the help of the authorities. 9e no longer needed to beg for funds and, freed from fina,ncial wo~ries,mas ablz to give his 51nole energy to the further development of his ai~ship. disaster, After the ~chterdin~erithe year 1908 brought fv-rt'ne~slJccessea which soon compensa.ted for the loss of the LZ4. The LZ 3, which had been damaged in 1907, and had been removed froin its floating hailgar to the stationary hangar at Eknzell in exchange -.for: the LZ 4, was soon repaired mith the aid of the people' s contributions. By lengthening it 8 meters (26.25 feet) its gas capacity was increa.sed to 12200 cr1.m (430,843 cu. ft) 2nd its useful lift to a5out 500 kg (1102.3 lb). The old two-su-rface rtdders, si-tuated between the stabilizers, nere increased by the ad-dition of a third surface. No large stsrn nidd-er could be installed, on account of its weight. The elevators were made larger and a dorsal fin was added, in order to diminish the rolling of the airship. In the trial flights, which began October 23, 1909, the LZ 3 proved to be extremely stable. The rudders and elevators sorked satisfactorily. The speed, with both engines nnning, was 12.2 - 'rn/sec (40.03 ft/sec) and, with only one engine, it mas 7.7 (25.26).

All the flights were of long duration 2.nd lzere accorn~lishedwithout accident. Worthy of mention is the six-hour flight of October 27, 1308, mith Prince Henry of Prussia on board; the flight of Novem- ber 7, 1908, to Donaueschingen to greet the Kaiser, with the Crovm Prince on board; and the exhibition flight before the Kaiser on Novernber 10, 1908. In March, 1909, the LZ 3, which in the meanwhile had passed into the possession of the government as military airship Z 1, was manned by an Army crew and made 26 successful flights up to 12 hourst duration and 1500 meters (4921 feet) altitude. It also made several smooth landings on solid ground. In a flight to Uunich, on April 1, 1903, the airship was carried east by a strong wind, landed at Dingolfing, and on the afternoon of April 2, aftez the wind 3ad subsided, proceed-ed to IAunich and returned to Kanzell in the evening. After the completion of the Army airship hangar in bzetz, the Z 1 mas .to be transferred to it on June 30, 1909. It was conpelled by a pouring rain, honever, to descend at Siberach and remain there four days tii~tilJuly 4, when it successfclly completed its.voyage. Tine Z 1 was stationed at Metz until 1911, and there participated in nany practice flights xith otter airships. Curing this year, as a consequence of r9building the waders on the ground of the favorable results obtained mith the airship llSchwaben, '' the speed of the Z 1 was increased to 15 m/s (49 -2 ft/sec) . It soon became obsoiete, ho~xei~er,and was dismantled.

Let us return now to 1909. mile the Z 1 aa.6 making its rilili- ta,ry practice flights, work was feverishly continued at Friedilich- shafen. Vith the naney contributed by the people, the new yard of the Zeppelin Airship Construction Company nas ?milt north of the city. At the same time, a canvas hangar was erected for the re- ception of the Z 1, so that the floating ha.ngar could be placed at the disposal of the LZ 5, which mas built in the old Yanzell hangar, for its trial trips. After the frame of the LZ 5 was fransferred to the floating hangar, the airship, which was to pass Znto the possession of the government as Z 2, mas there completed. It did not d-iffer essentially from the LZ 4. The passenger cabin in the middle of the aalk-way was omitted. A few improvements nere made in the steering gear and above all in the lubrication of the engine. The latter condition was very- inportant, since Count Zeppelin h~psd to make FPith this airship an endurance fli.ght-surpassing, both in duration and distance, the sti.pulat,ed condit5on.s for the 24-hour ,flight. Tne essential conditions mere good xeat5er and the holding out of the eiigines. The LZ 5 made its first trial flight on May 26, 1909. It pve no cz.use for uneasiness, so that Count Zeppelin decided. to undertake the endurance flight at once. On May 28, the fizst attempt was made, but after a short time it mas decided to return, ss it had begun to rain. On the next day (Kay 29) the LZ 5 started again. The airship carried a crew of eight men, 600 kg ivater ballast and over

2000 kg (4409 lb) of fuel, sufficient for the simt~ltaneousoperation of both engines for 34 hours. The intention was to reech Berlin and so the .flight procesded over Ulm, Treuchtliilgen, Nurenberg, Erlangen, aayreuth, Hof, Planen,

Gera, Leipzig, the latter place being flom over at 5 -p.m., May 30:

Just as on the Mairrz trip, a strong lift -172s pilo6uced by the expan- sion of the gas due to the heat of the sun. 3ith the comparatively veak engines, the upmard tendency had to Se overcorns by pointing the airship downward, thus retarding its progress, so that, after passing over Bitterfeld at 7 p.m., there mas no prospect of reaching Berlin before midnight. Count Zeppelin, therefore, decide& to turn back, especially because the fuel supply would not ot,herxise be sufficient for a non-stop return flight to Friedrichshafen; and he set a very great. value on making a non-stop endurance flight with return to the starting point. With a northeast vind at its back, the ship flew very sniZtly until it rezched the Thuringian Fcreat. Here the wind changed to the west and mnsider3bly retarded the airship. At 7 a.m., Xay- 31, Crailsheitii w2s reached, vith only fuel enough left to run both engines 7 or 8 hours. At a lon speed Stutt- gart was flown over at 9 o'clock and Plochingen an hour later. Vith the increasing xlnd, there nag no longer any possibility ~f reaching Lake Constance In five hours. The LZ 5 tLerefore iiescendsd. on a meadow near Sblppingen, but its nose struck a pear tree, thereby danaging the hull more or lees back as far a.s the for~mrdcar. The accident mas dl~eto the ex- hausted condition of the c-ew which, in their enceavor to make the e~durancetest successful, had h2.d little rest for nearly 32 hours* On the first ner!s of this accident, the flight, v:hich had been followed mith general solici t-dde, seemed 50 hase te~ninateddi s&s- trously. But not so. Ths englneer ~)~rr,s;ho he& 7a~ticipatedin the flight, succeeded in teriipol-arily repairing the damaged nose with a wooden structure, so that the airship wds enabled to make the short flight to Frbedrichshafen. After necessary repairs, it ascended mith a smaller Clem toward evenin? of June 1 and-, after making a stop at Schemrne~berg, north of Biberach, reached. Manzell early in the morning of June 2. The result of this flight, like the result of the Vxnich flight of the Z 1, mst have opened the eyes of the opponents of rigid airships, for mhat they had regarded as impossible with Zeppelin airships (the strength to resist the shock' of hard landings and making repairs en route) has been demonstrated by the facts. There vas a . 3. tendency, however, to ascribe these Itaccidentel successes11to fcvor- able weather conditions. Naturally, these had something to do with

the successful outcome of. the flights, Sut such results would have been impossible ~~~ithoutthe excellent structural characteristics of the Zepnelin airship$. Moreover, the engines had functioned perfectly throughout, showing that the right course was being followed in this respect.

After being repaired and taken over by the war department, the LZ 5 was named the Z 2 and was transferred to Cologne on July 31.

the way, it made a stop the grounds the International Air- ship Exhibition at Frankfort-on-the-Main. For the first time, opportunity was here given a large con- course of men from all parts of Germany and from foreign countries : to obtain a personal impression of the Zeppelin airship. This im-

- pression was voiced on the following day (august 1) by the "Frank- furter Zeitungtl as foll-ows:

# "As the airship passed before our eyes in a flight of almost an hour and a half, we became so accustomed to the sight that all our doubts vanished. As it sailed majestically through the air, every one was brought under its spell. The impression was deeper than could have been made by a thousand ever-so-convincing pens. It was the pomer of actuality, of one's own experience. ItThus it sailed triumphantly over the land. It descended slowly, the ropes were throm out and it mas dram gently to the ground, mithout any of the oft-proclaimed difficulties of landing. There it lay, after a few surprisingly simple precautionary measures and only i+s nose oscillated a little in the win$.

"One is impressed by the s~i~~etryand slee-imess of thz 7i;:101e st~uctu~e,as well as by the care with wnich a21 the ketails 'hxire been worked out. Eve;-pvhere dilf-gpnt, solid ';e~rnan ~orkrll~x1slj5p-is evidenced. Here old established safety limits heve not Seer?. sx- ceeded and the engineer and scieiltific expert have not been forgot-.

.teng HOW simply the propeller brackets are attached to bull! .I?OIT neat and srnooth is the driving gear! Rere is ~eigntvhere it be- longs. The cars are neat and smooth. They are made entirely of . sheet aluininum and very gracefully shaped, "The smoothness of its exterior gives the airship the minimum air resistance. There is not mch on the 0utsid.e of the airship, but what there is, is sufficient and in the right place.M In a 'laater edition of the saizle date, Dr. Alfons Faquet says: "Can the few bold aviators up there in their cgrs know how we. feel here below? Have they not already cast off much ill their enviable freedom and power? Can they understand how the sight of this wo-sl- der affects us earth-bound creatures? Can they silspect how the oner- powering impression of the conquest of the air grasps and convulses us like an electric current flowing from heart to heart? A che.et. for the great white ship! A cheer for Bhe giant projectile vhich speeds through the sky and brings not destruction 7.vhere it goes, but joy and brotherly love! A cheer for the fulfillment of manzs drearn ! Soon after the transfer of the Z 2 to the Army, a new airship , by the Army, altkough no o~derhe& been given for its canstr-~c'"ion. The LZ 6 differed from the Z 2 osly i-r, its soinewhat rricr8 pcmey- ful engines, its tvo-bladed. propello,rs an< its steel-be1.l drive. 1n. comparison with the former bevel driving gear, t3e steel-Tjel!; &riae

had the advantage of economy of pover and weight. On its first trial trip (August 251, nothing detrimental was discovered. Count Leppe-

lin ventured therefore, although the new driving gear had not been - sufficiently tested, to start (August 27; on the trip to Be~lin,in order to fulfill the wish of the Kaiser arid the inhabitants to have the airship reach Berlin August 28, and land on the Tegeler shooting

. range. During the journey, it soon became evident that the new drivi,ng gear was not suitable for airships. It proved iiipossible to so ad-

just the pulleys on the engine shaft and propeller hub that the distance 'between them would alxays remain the. same, thus preventing excessive stresses and consequent tearing of the steel 3elt- It was only due to the otherwise good characteristics of Zeppelin construction that the flight did not have an unfortunate outcorae. The LZ 6 had left Manzell August 27, 1909, at 4:35 a.m., pilot- ed by Chief Engineer Mrr with nine persons on Soard. The- intention

. was to land in Bitterf eld on the field of the Parseval Coin?acy, where Count Zeppelin awaited the airship, and thence to proceed on the afternoon of August 28, with the Count on board, to Berlin, azd

to land on the Tegeler shooting range in the immediate vicinity sf the airship crew!s barracks. At first all went well- end -:he LZ 6 reachsd Ulm in two hou-s. an account of a damagzd propellzr, s stop vas imGe half-my between Nordlii~genand Nurernberg in the ~'icixiltyof CTunze~haasenilear 0s.:- heim. After the substitution of a. spare propzller carrie6 on the airship, the jou~neyvias continued, but soon had to be interrqJ6ed again at ihtzenteich near iuirreaberg, in order to repair the fomsrd engine. After replacing the damaged parts; another start was mcde at 2:15 z.m., August 28.

In the meanwhile, t'ne eath her kd gzom bad. It bek@n to rain and the airship could make but little headmay against the fresh north dnd. It got along better later in the day and, after losi-ng a progeller in the vicinity of Schmo1in.-near Xonneberg, landed a.t 6:30p.m. at Bitterfeld, after a flight of 163ours. The enthsiasm here ??as tremendous. Thousands of people had asseinbled fzon the immediate neighborhood and from the surrounding toms and for twelve hours had patiently awaited the arrival of the airship. Berlin was consoled the following day, after klzving been in- formed that it v~ouldbe izpossible for the airship to arrive August

26, in accordance with the original schedule. On August 29, the weather had improved and %he airship arrived over the capital city .at noon. After sa.iling over t'ne southern subu~bsand then over the

Tempelhof er Field, the Castle, Cathedral, Gity Hall, ~raild-enburg &.te, Reichstag 2nd Tiegarten, it landed on the Tegeler shooting r2,nge. The enthusiasm of the inhabitants knew no bounds. Every one felt the import~nceof the occasion. After the landing and the greeting of the crew by the Kaise?, Burgonaster Reicke delivered a short address of ~elco~e. -- eihat Count Zep?elin had felt in the flight ov2r Berlin, he ex-

pressed a few days later in a letter to 3urgoi.naster Eeicke. 3e said in >art: "Mot for several years of my life mould I have been i.fillii?g to miss the hours of gazing down oil the giant city awaiticg me in holiday attire and the feeling that the hearts of the millions of waving and shouting people were dravm tovrard me and my work ~ith

eager enthusiasm. It

Only a short stop mas made in Berlin, since on September 3-4, members of the Federal Council and the Im9erial Diet were expected, whom Count Zeppelin wished exhiblt the airship. The return trip was accordingly begun just before midnight on August 29, after replenishing with gas arid fuel. Near Wittenberg, the front starbosrd propeller broke, throwing

fragments through the airship and damaging one gas cell. Engineer Diirr then brought the airship to land at B~lzig,since it would have been impossible to make the long flight to Lake Constanc'e with the rear engine alone and the uncertain new power transmission. Idore- over, it seemed advisable to make a thorough investigatioiz of the danaged cell and, if possible, to make immediate te-qorary regairs. Two three-bladed propellers from the Z 2 with their cardan driving gears mere ordered from Cologne. Three days had elapsed by the time. the missing parts had been received and installed a:ld the gas cell and outer covering of the hull had been mended. The task had been a, very difficult'one, as the airship mas tossed to and fro by grzsts of wind and mas held only vith the greatest difficulty- N~xh credit is due the craw which had been oh the way sigce A.1~;csi-27,

and had succeeded in mastering sll the co;;s-tan-'7yud. a;ising di.PI2cuI- ties. September 1, at 11 p.m., the LZ 6 made anot3er sCart ai;.iL, after a non-stop flight of almost 23 houi-E, reached Friedric'rlsi?zfl23 at 9:40 porn., September 2. Thus the Berlin trip. mas successful after all. It deacilst~at- ed, however, that too much should not be expected of an airsnip in its still i~perfect state of development, and especially with in- novations which had not been sufficiently tested. On the other hand, it also demonstrated tha.t the Zeppelin airship, in spite of its technical defects, possessed excellent qualitieso I have purposely gone into the details of .the first long dis-

tance flights over German territory, in ordei to show what advant- ' ages the Zeppelin airships possessed-, even at that time, and what ability the Count and his coworkers had exhibited in mastering difficult situations. This was shown in the unplannzd stops of the

LZ 4 at Oppenheim and Echterdinger, of the Z 1 at Dingolfing and Biberach, of the Z 2 at Schemmerberg and of the LZ 6 at Ostheim and Bulzig. In technical circles the zbility of the 2eppeiS.n airships to make such landings had been constantly disputed. The possibility of temporarily repairing the hull was demon-

.. strated in connection with the G8ppinger accident. At BCtlzig it

' also demonstrated that it was possible to repair individual parts without any protecting shelter. , The collision of a nonrigid airship with a tree would at I least result in the immediate loss of all the gas and probably 33-2-

ther damges would be unavotdable. In any event, it would liot bi.

able to continue its journey. And what wou?-a '~eomeof s nor-rig2.2 airship, if portions of .the propeller shou?-d penetrate the encslcpe during flisl~t? The gas mould immediately escape and the airship plunge to the ground. Such an accident mused the destrdction of the French nonrigid airshi? "Republique1I which fell 400 meters at Trevel, September 25, 1909, after a propeller blade had flown off and penetrated the hull. In such a' case, an airship divided into a number of cells would lose only a certain pazt of its lift and in most instances would be able to off set the gas loss by releasing ballast. Still it mould be a one-sided view that would cause us to decide for or against either the rigid or the non~igidairship. As - a matter of fact, the technical defects of either airship can be eliminated in the course of time, as the result of experience.

Both types have e~hibitedstriking advantages agd are well wor-th developing. It is too soon to talk of the wor'uhlessness of either. one. Should it prove in the course of d-evelopnent that, due to certain inherent defects of the type, the desired results cannot be obtained, me vould always be at liberty to i-efuse it our support. It seems strange, therefore, that the mar department has shorn a certain aloofness toward the Zeppelin airship- After taking cver

3 the Z 1 an6 Z 2, it refrained from the adoption of any more Zeppelin airships. I will explain the reasons for this course latsr.

. In contrast mith the reserve of the war department, stood the general enthusiasm of all Germany, due to our successes in the

f icld OF airship travel. The present general indifference tornard

ol-1s aviation problems is sozlething to be ashamed of. Ve must al-

T.vays enphasize the fact that a goodly shere of the total develop- aent was made by us and- we have reason enough for continuousiy em- phasizing this fact and keeping it in our :i~emory, until we are aga.in called to participate practically in its further development.

B11t to retun to the 52, 6. After being overhauled, it was stationed at t3e International Airship Exhibition at Frankfort-on- the-Main, where it took part j.n the "Kaiser Manecversfl and demonstrated its reli~bilityin nuinezous short a,nd long flig%ts. After returning to IJanzell, experiments with radiotz!.egraphy were begun, both sending and receiving instruments being ixstalled in the rear car. It .-as found possible to receive messages from s distallce of

500 !_an. i\So objectionable phenomena occurred. 'J;ihile sending mesh - sages from the airship, clin1'~ingand the release of gas Kere avoided, so that the sparks could not set fire to the zirsn5-p. The low speed of the LZ 6 led the Zeppelin Cornpany to install a third engine on a platform erected in the middle of the walkmy. As this did not give the ex-ected increase in speed, it mas soon a-bandoned. IGoreover, the presence of an engine at this point was ' precarious on account of the danger from. gas. When the airship is ascending, gas escapes through the safety valves in the botton! of the cells intc the malk-may, v:here it form a highly e:cplosive mixture with the air. In ~ctober,1909, trisl flights mere made in Cologne with the Army air&?lpsP 1, M 2, and Z 2, in which the Z 2 cornparee unfavor- . ably with the other t~oin its carrying capacity and speed, as also

in its responsiveness to the mZder. * On account of its smaller size, however, it. has easier to handle on the ground and reqilired a smaller nu-m'oer of men to take care of it. Thus it hap?er,ed that the LZ 6, notwithstanding its many long flights, was not accepted by the Amiy administration. The latter took the standpoint that it v;ould again try the Zepoelin airships oniy after considerable im- prov'ement in speed and carrying cxpacity should be attained. The Zeppelin Sor;?pany could be put in a position to meet these requireaents only by receiving orders for building airships, since it did not have sufficient funds for building and trying out experimental ships. Practical operation, howzvrer, was the o31.y way i-n tvhic5 the airships could be developed and inlproved. Cesigns, which promised the best results on paper, .often turned out to be - failures. The task of assisting in the further speedy development of the Zeppelin airships fell to 'the !'Deutsche Luftschiffahrts- Akti en-Gesellschaftlf (~elag), which was founded in Novenber, 1909.

9 The "Delag" owed its origin to the men vho, supported by the general enthusiasm over the Zeppelin successes, had 'oeen abie to secure the funds for the installation of airship ports in ~idely separated places. They assumed the task of inaugurating sir .traffic xith Zeppelin airships. Fox lack of sufficient hangars, no regLilar air traffic betmeen cities could at first be estzblished, so that it ~;sslimited to round trips in the irmediate vicinTty of an airship port. The first Delag airship, SZ 7, nsirned it~eutschland,"nss Built in the cew Friedrichshafen yard and made its first trial trip June.'.:

. -7 -- ~?LO. The need of a greater carrying capcity xa.s met by increas-

r ing the gas capacity over 400 cu.m (14126 cu.ft) to 19300 cu.m (681520 cu.ft) by increasing the dianeter one raeter (3.28 ft) to 14 m (45.9 ft), and the lengtin 14 ak(.4.5.93 ft) to 148 m (485.56 ft). By adding a third sngine, the.speed vas increased from about 13 m. t.42.65 ft) to 16 m (52.5 ft) per second. The engine in the front car drove 2 two-bladed propellers, vhile the 2 ea@nes in the rear czr each d.rove a four-bladed propeller. Tubular shafts and bevel gears were ecqloyed and reversing gears were provided for both rear 'propeliers. The elevators were given their forther shape and location. The rudders were rrodified again and were made simpler by the elimination of the large oval stern.rud.der. In the middle of the ship, the walk-way was sidened into a comforta'ole cabin for 16 persons. me !'D.eutschland'! vas short-lived.. On June 28, 1909, only nine days after its first ascent, it was wrecksd by a storn in the . Teutoburger Forest. The loss of the "Deut~chland~~was mailzly dxe to a partial failure of the engines. The resulting loss of speed left the airship at the mercy of the storii. A whirlwind lifted the ship high up, thereby occasioning a great loss of gas, the effect of which could

not be offset quickly enough by operating the elevators and releas- izlg ballast. FortunatePj no life was lost. Confidence in tile idea of a passenger airship, however, was given a severe shock. This accident handicapped the Zeppelin project all the more, because two months earlier, on A~ril25; 1910, the Army airship Z 2 had fallen victim to a storm at Weilburg. it was important to have another passenger airship soon, in order to dispel the prejudices occasioned by these accidents. It rould have taken too 'long to build a nei airship and it was accordingly decided to rebuild the LZ 6, which had not been used after its trial flights in October, 1909. After lengthening it 8 meters (26.25 feet) and adding an 18th cell, it had a length of 144 meters (472.44 feet) and a gas capacity of 16000 cu.m (565000 cu.ft). In addition to the two Daimler engines of 115 HP each, a 140 HP Maybach engine was installed. The innovat ions of the I1Deutschland" were retained as regards the engine arrangement and transmission. The radiators which, on former airships, mere located behind the engines, were likewise installed, the same as on the 3 llDeutschland,u outside the cars and alongside the walk-way. The latter mas extended beyond the cars. The elevators remained un- changed in the same location, but the rudders were again altered. The I1Deutschland" had six rudders, all located above the stabilizers, while the LZ 6, in contrast with the LZ 7 (which had only one sta- bilizer on either side) retained its former arrangement of two pai.rs of stabilizers, the rudders coming partly between the stabilizers and partly under them. The LZ 6 was not destined, however, for a long life. After it had made, from the new hangar at Baden- Oos, 36 trips on 18 different days between August 23, and September 14, 191.0, it was destroyed by fire in the hangar, through the care- lessness of a mechanic vhile cleaning a car. ! It was now imposs5ble to resume passenger trips in the year 1910. The airship "Ersatz Deutschland1I (LZ 8) which mas made from

the material and on the same plan as the LZ 7, could not be finished before the next spring. On April 11, 1911, I1Ersatz Deutsch- land" moved into the '~fisscldorfhangar. it was not used very much,

on a.ccount of bad weather and the difficulty of getting it into and out of the narrow hangar. On May 16, when it vas desired to .re- move the airship to Saden-Oos, it mas driven against the hangar and damaged so seriously that it had to be demolished.

I must say a few words here regarding the hangar problem, since it is closely connected with 'the development of Zeppelin airships, as well as with the above-mentioned accident. Airs,hip traffic can be carried on only where the longitudinal axis of the hangar is situated in the prevailing wind direction. Otherwise, even a very light mind will render it impossible to bring the airship in and out of the hangar. In a valley or alongside a mountain range, there is no difficulty in maintaining air traffic, provided 0 the hangar is parallel with the valley or the side of the mountain.

In other places the best nay to locate the hangar can be determined only by extended observations of local weather conditions. Thus, for example, the location of ~fisseldorfwas unfavorable, while that of Baden-00s was ideal. The construction of revolving hangars was very expensive and not practicaiole, considering the fi- nancial status of airship trsffic at that time. The only thing to do, therefore, was to restrict airship traffic :to favorably located havens, until it shoriid be pdssible to build hangars vitb tmo doors and mith sufficient width. In this connection, great care rmst be exercised that auxiliary measures, like tracks and wind

shields, do not form additional sources. of danger for the airship. .

It was mith these facts in mind that the Delag, after the loss of I1Ersatz Peut~chland,~~in the late summer of 1911, again undertook to resume passenger flights from Baden-00,s with the airship ltSchmaben.n The Delag was perfectly aware that this experiment was the last it could venture to undertake. In case of failure, the fate of the Delag would be sealed and perhaps that of the Zeppelin Airship Construct ion Company a1so - TQe t'Schmabentl ca.me up to the expectations. Its properties were better and it was also luckier than its predecessors- It blazed the way for the further development of Zeppelin airships- In .spite of its small size, its carrying capacity was no less and its steering gear worked better. It also attained an adequate speed, which, in comparison with other types, the Zeppelin airships had hitherto failed to do. It made as much as 19.3 m/sec (63.32 ft/sec) or about 70 krn (43.5 mi.) per hour, thereby surpassing the "Deutschlandtl by abou;t 15 lun (9.32 mi .). This irnprovernent was attained, in the first place, by employing the more powerful . .. and reliable' Maybach engines and, in the secoiid place,'by eliminat-

ing all unnecessary head resistance. Under ' this head comes the transference of the elevators to the stern. In thus bringing all the steering surfaces to the stern, the many experiments regarding their location came to an end* kt first no one credited the results, the hi@ speed, especially, being considered imp0 ssible. Doubt and prejudice gradually gave place, however, to perfect confidence, as representatives of the. central authorities took part in the trips and satisfied themselves of the genuineness of the performances. Many were convinced, moreover, that the Zeppelin was destined to be the airship of the future. Between the middle of July and the end of November, the Schwa- ben made 130 trips without an accident. Flights were made over South Germa-ny, the coast of the North Sea, Berlin, Saxony and Thur ingla. The successes of the Schwaben soon began to show results. The war department awarded the contract for another Z 2, which could still be delivered in 1911, after the LZ 9, already built by the Zeppelin Company, for experinental purposes, had undergone the reg-

. uisite modifications. It was in every re'spect a sister ship of the Schwaben. The reduction of the head resistance by the removal of

the passenger cabin increased the speed of this airship to 21 m/sec (68.9 ftlsec). The Z 2 rendered the war department good service for a long time, but when the war broke out, it mas dismantled as obsolete. By reason of the success of the Schwaben and the building of air ship hangars in Frankf ort-on-the-Main and in Earnburg, the Delag

was soon able -to add a second and a third airship. The LZ 11 1 1912. They differed from the Schwaben in their greater length - 1 148 m (485.6 ft), and gas capacity of 1870G cu.m (660390 cu-it). The passsnger cabins were roomier and nearer the forward car. The rudders ahd elevators were made srnal-ler mithout impairing their efficacy. They all lay entirely below the stabilizers. This ar- rangenient was retained on the 13 following airships* The success of the Z 2 led the war d-epartment to order another airship, the LZ 12, which mas taken over in the early summer of 1912. It was an exact duplicate of Z 2 and, like the latter, was equipped with a radio outfit in the walk-way, the power being de- rived from the for,ward engine. The Wavy now began to take an interest in airships and ordered the LZ 14, which began its trizl flights as the L 1 in October, . 1912. It had a length of 158 m (518.37 ft)', making it 10 m (32.81 ft) longer than the previous Zeppelins. Its diameter was increased from 14 (45.9 ft) to 14.86 m (48.75 ftj. Its gas capacity was 22465 cu.m (793351 cu-ft), and its carrying capacity was increased from 6000 (13228 lb) to 8600 kg (18960 lb). Its speed was also slightly increased, in spite of its larger size. - The L 1 was the fourth airship built at the ~riedrichshafen yard in 1912. The capacity of the yard was increased, so that it was able to build seven airships in 1913: five (Lz 15 or Ersatz

1, LZ 16 or Z 4, LZ 19 or Z 1, LZ 20 or Z 5, LZ 21 or Z 6) for

the Army; one (LZ 18 or L 2) for the Navy; and one (LZ 17 or lfsachsen") for the Delag- - 67' -

Ersatz Z 1, Z 4, Z 5 aria. Z ij were sister ships: They had a larger diameter, 14.86 ril (48.75 ft), and a shorter length, 140 m

(459 .fJ~),than the Delag ships. The war department, in spite of its coristant demand for increasing the carrying capacity, desired to restrict tne length, for greater ease of managing on the ground, aid soilght to increase the carrying capacity by reducing the dead load. The adoption of the now sufficiently tested ffgoldbeaterl.sskins" (made from the large intestines of cattle and hogs arid lighter than the rubber fabric previously employed) helped in this respect. Gold- beater's skins are, moreover, less dangerous, since they do not have the electrical properties of rubber fabric, which, e.g., caused the burning of the Schwaben. The demand for flight at higher altitudes could only be satisfied with the lapse of time, by increasing the gas capacity. The

LZ 21 was therefore given a gas capacity of 20870 cu.m (737024 cu-ft) nith a length of 148 m (485.6 ft). The Sechgsnn (LZ 17) had the same

dimensions as the Army airships Z 1, Z 4, and Z 5. A later type was represented in the meantime by the LZ 18 or L 2. The L 2 mas the first airship to h.ave the walkway inside. This arrangement was adopted for the purpose of increasing the speed by decreasing the drag due to the keel-like walkway of previous airships - The L 2 had a gas capacity of 27000 cu.y (953500 cu.ft)', with a length of 158 m (518.4 ft) and a diameter of 16.6 rn (54.5 ft) (an increase of almost 2, m (6.5 ft) )- The carrying capacity ms corre- spondingly increased, thus rendering it possible to install a fourth

ergine and to carry tu;o, crews for long voyages. The four 165 HP engines were placed in pairs in the two-power cars, each engine

driving a four-bladed propeller. It was possible to reverse all the propellers and also to drive two propellers with one engine. The latter provision importance for ena,bling the airship to keep its course in case of the stopping of both starboard or both lar- board engines.

The rudder and ' elevator controls, the telegraph instruments for transmitting orgers to the engineers, the ballast and valve controls, comyass, gas and air thermometers, variometer, etc., were no longer placed'in the forward poaer car but in a separate control car located still farther formard. This car tms protected from the ,'wind by glass windows. The radio outfit and the rest room for the .unoccupied crew were placec? amidships. During a trial trip on October 17, 1913, the L 2, shortly after ascending, fell in flames at Johannisthal. Since the radio station was not yet in operation, the blame can only be laid to the construction. After the removal of the hanging malkway, the power cars had been brought nearer the hull. Their forward side was encased in glass in order to protect the engineers from the srind. Behind these wind shields a suction was created ~~hichdrew the explosive mixture of gas and air under the airship into the cars, where only a spark 7 - from the magneto would suffice to set it on fire and put the whole airship in flames. Doubtless, such an explosive mixture was pres- -- 63 -

I cfit, since during the asceni of the L 2, gas escaped from the safe%y valv~son the lower side of the gas cells into the mlkway and thence irl the vicinity of the poner cars. Had it not been for the glass nind shields, the explosive mixture would have been inmediat ely ca.rried away by the draft. Numerous tests made on previous trips had failed to disclose the presence of any of the explosive mixture in the power cars, so t5t-tmay;: be reasonably assumed that this danger could be eliminated by extending the. wind shield over the top of the power car. This otherwise objectionles~method of construction was, however, abandoned and the plan with the underneath walk- way vas resuiiied. The subseqdent develop~entof the a.irship showed, 1 however, that only a slight modification woul6 have sufficed to pre- vent the explosive mixture 'from entering t'ie protected cars. After the war department had experimentee- with several Zeppe- lins, and had studied out the necessary equipment, it was abbeib6e adapt them for observation and attack. For the former purpose, the installation of machine guns was necessa,ry, in order to drive off attacking airplanes. For the latter purpose, devices were necessary for carrying and dropning bombs. Since it was impossible to fire from the cars at any aircraft above the airship, it was necessary to install a machine gun on the

I top of the airship. me Z 4 was the first to have such a platform,

I I . which ;ms placed about over the forvard car. Exhzustive experiments I ' Only while I had shorn thet firing fron this point mas objectionless. 1 the airship was climbing, it sas desirable to avoid firing, if pos- I sible. For greater safety,. the balloon fabric in the immediate vicinity of the platform was impregnated mith some non-iilfla.mn2;ble substance.

The bomb-dropping device nas very simple at first. On account of the small meight of bombs :.ihich it mas possible to carry, the bomb racks mere at first placed in the middle of the walkway and provided with wires for releasing them from the sighting room which mas also in the walkway. c . Thus, on the one hand, the total meight of the airships was increased by these indispensable accessories, while on the other hand, it was sought to reduce the dead load in every way possible, the use of the light goidbeater's skins being of considerable help- The lightening thus effected mas small, however, in compa,rison with that required for attaining a sufficiently high altitude for war pur-poses. It was therefore decided to make the next airships, LZ 22 and L LZ 23 (Z 7 and Z 81, 156 m (511.8 ft) long, thus increasing the

flight altitude 200-300 m (656-984 lbs). Tlie Z 5 and Sachsen, already in service were likewise lengthened from 140 (459) to 148 m (485.6 ft). The war department had an ifiterest in the Delag airships (Viktoria-~uise,Hansa and ~achsen)and supported the company by a yearly subsidy, on condition that their airships should rieet certain requirements and should be a2t the command of the war department in case of war.

L 3 (Lz 24) and Z 9 (Lz 25) were finished shortly before the

war. Both differed little from Z 7 and Z 8, but carried about 700 kg (1543 lb) more, with an additional gas capacity of only 160 cu.m (12713 cu.ft). They were equipped nith 210 HP engines, instead of the former 165 IiP engines.

On the Z 9 the stern steering apparatus was considerably simpli-

f ied by making the elevators continuations of the horizonta:L stabilizing surfaces and the rudders continuations of the vertical fins* Ths lateral steering, which had never before been entirely satisfax- tory, now gave no more cause for complaint, even when only one propeller was running. With the Z 9, after repeated changes, the ex- peximental stage, zs regards the steering gear of the Zeppelin airships, was brought to a close. Only sl-ight changes, chiefly in the tension of the surfaces, have since been made. The military airships mere not yet sufficiently developed for war, but their cooperation was needed and they were set to work'. It was found, however, that they could not make, as had been hoped, long observation flights by day over the interior of the enemyt s country. They were not able to attain sufficient altitude and most of them soon became the victims of iiifantry and machine-gun 'fire.

. Only in the Eas%, where the defense was less, could such flights be made with impunity. Hence, airships, were soon used for night bomb- ing raids. Even here, however, the constantly improving defense necessitated flight altitudes of much more than 2000 m (6561.6 ft). At the beginning of the war, the Navy had only the L 3. Like the Army, which had lost four airships during the first month of the war, it desired to increase the number of its airships. Since

the type L 3 to Z 9 showed considerable improvement in lift, ten airships of this type mere built by February, 1915. The construction company was better prepared for this accomplishment, since an sen had been lengthened.

At the saine time, new desi-s were made for more efficient cu .m 25000/n (882875 cu. f t) and 30000 cu.w ( 1059450 cu. f -L) .airships- The first airship of the former type, the LZ 26 (Z 12), mas finish- - -

, ed in December, 1914, in the FrankfortI hangar. This airship ccmbin- 1 ed an increased speed with a surprisingly large carrying capacity. ! Its gas capacity was only 2500 cu-m (88288 cu.ft) greater. The

, greater,lift was mainly dve' to the reduction in the number of gas

1 cells from 18 to 15 and to their being made of goldbeaterst skins. The Z 12 was a transition type between the former airsnip types and the L 2. The viralkway betneen the ton cars was located in the usual way, underneath the hull and vas widened in the middle to provide room for the rad.io instmments,' a rest room and the bomb-dropping - device. Above the cars and .in its extensions both fore and aft, the walkway was inside the hull. The cars were not inclosed and were hung a little lower than on the L 2. The same distance from the hull was still maintained when the ship was p~ovidedmith closed

cars. In contrast mith the L 2, however, a space of almost 1 meLer (3.3 feet) was left betwen the bottom of the hull and the top of the closed car. Thus, any gas escaping from the hull was carried away by the wind and could not enter the car. The rear propellers were mounted, as previously, on lateral brackets attached to the hull and were driven by tubular shafts, but the front propeller was mounted on the rear end'of the lengthened engine shaft. By the latter arrangement a saving of power was effected and the air resist- . mce or drag, due to the brackets aid extra shafts, was dirfiinls1:e:l. The only disadvantage was that the foraard propeller could n3-L run I while the landing was being made. Begimir~g3ith the L 3, tile pro-

- ,pellezs mere all two-bladed and made of wood.

The Z 12 ??as t5e first airship fitteZ with a look-out basket. This was a smal!. observation car in the form of a boat ~hichcould be! lowered by means of a cable a,nd wigch in the rear .car to 1000 meters below the'airship. The ;;rir~chcould be operated by a notor or by

hand in case of failure of the motor. ' The obser-rex in the look-out basket was connected by telephone with the control car and, when the airship found itself in or above clouds, co~lCbe let dc~mto the lower edge of the clouds and frorn there direct tile navig8.tion of the

ship. The basket ms carried by the wind fa;. back under the stern . of the airship, so that it did not interfers wit5 the dropping of ,bombs. Due to its smallness, the discovery of the basket in the night by means of searchlights mas practically impossible and! shooting a$ an airship hidde~lby the clouds, with only the sound to go by, stood small chance of being successful. This device rendered it possible, after the first failures in August, 1914, to continue the raids on moonless nights and even in cloudy reather. This was the real reason for equipping the militar? airships vith look-out baskets. Aside from war raids, i.n which the airship sailing above the clouds was directed to its goal by tne o'oserver in the basket, a.ny airship encountering clouds could thus be steered to its haveil. h at f e;m airships, however, mere equipped with such a. look-out basket. ~ostcornmz.nders with ships of xoderate lift preferred to do without it, since it weighed about 50C kg (1102.3 ib). The 25000 cu.m (882975 cu.ft) tType continiled to exist in modi- fied form only ,in the L 3 (Lz 36) of the Ikvy anu in the! LZ 39,of the Army. These eirships, unlike the,Z 12, had the whole waljc~ay

. ' inside the hull. The radio station, formerly In a ~rideningof the

mzlkaay, nas transferred to the fo rmard power car and fed. by the engine there located. The control and power ca.r Tere su~peilded

separately and simplj- cornmnicated with e~chother through a door. This separate suspension was vindiczted by a peculiar accident which happened subsequeatly to the LZ 39. This airship mas seri-- oasly illjured in the stern by a shell f-i.a.gment. As a ccnseqv-ence of the loss of gas, it could only be kept afloat in a very oblique position. This resulted in the shifting of the pomer car, so that the propeller struck the bottom of the hull, causing the whole power car to break loose and plunge to the gro~nd. The control car was saved from fallii~gwith it by being separately suspended. henew 32000 cu.m (1150080 cu.ft) type pas coiwleted siimltan-

~OUS~Ywith the L 9 alnd LZ 39. It was only 2.1 m (6.83 ftj longer' tha.n the 25000 cu-m (882875 cu-ft) type, -mt had a dia.meter of 18.7 m (61.35 ft) instead of 16. The shape of the airship, which otherwise held to t3e innova,tions of the L 9, iva.s considerably improved. Most important of all qas the increased taper of the stem. T'ne power plant consisted of four 210 HP engines, one of which was installed in the f~rrnardcar zrid three in the, rear car- The for~~ard engine, as also one of the engines in the rear car, transolitteci its power to a propeller situated at the rear end of the car on an ex- tension of the engine shaft. The other tno snginss drove, by means

of tlrbular shafts, .propellers located on brackets on either siee of the airship. These propellers coul2 be reversed. .The speed was

26 mlsec (85.3 ft/sec) or about 3 m (9.84 ft) mrs than, that of. the L 9. This gain was due pa.rtly to the increase in engine power a22 partly to the more favo~akleshape of the airship. Con-brary to expectation, the handling of t3e big sirship an the

ground was only slightly more d.ifficu1-t than that cf the earlier types. This was partly due to the transfer of the. -walkway to tile inside of the hull, thereby reducicg the surface exposed to lateral

With the introduction of the 32000 cu.m (1130080 cu.f-k) airships, of which 10 rent to the Navy and 12 'to the Army, airship avi-

* ation received a great impulse. The period fram the summe? of 1915 to the spring of 1916 witnessed great successes without noteworthy 4

losses. ' Tilerever they mere sent (in the west to Faris and London and other parts of France and England; in the east to Riga a,~d Rowno; in the southeast to ~aloniki),they provea equal to their tasks - Their carrying capacity enabled the transpor-bation of s~~ff i- cient fuel for long trips, in addition to 2000-3C00 kg (4409-6613.8 klq)... of bombs, more than could be carried by a mhole sauadron of airplanes at that time. Before dropping their bombs, they could reach an altitude generally beyond the range of the anti-aircraft guns . of that time. There were as yet no aviators to be fea,red at night.- The airships were abundantly provided with machine guns to repel aiiy airplane attacks at dawn. As a mle, there were two or thres guns or! tile upper platforin and one or tvco i.n both t3e forward a:xi rev cars.

Oeta on the carryj-ng c=e.pacity srz give2 in the Loilc)wS.rAgC 53,'ol c

The variatio~sin the data :or the sal!ie aizshi2s are

-lions in ternperaturs 2,nd atmospheric 'press~are. For e~arnp2.e~-che . . lift of a 32000 cU.ia (113Q080 cu.ft) airshlp is refiuced about 100 kg (220.5 lb) by a rise of 1°c in the tanpersture of. the air an5 about the sa,me by a decrsa~eof 2.5 rq~( .0984 i~?.) Iig in the baro-- metric pressure. The amount of fuel to Se ca~riedvas de%erini.rsed by the distance of the goal., the speed oI" ths airship and tne direction and veloclty of the mind. The amounJi, of wa.ter ballast required for attaining the desi-red altitude was calculated, after m~~king

allowance for the wetght of fuel $0 be co~sumedbefore reac'ilir~$ the .' goal. The balance of the caryying capacity w2s then 3veila'ble for

'combs. A definite standard could not be a.dopted, since the coadi- t tions (such as the dropping out of an engine and the consequent reduction in speed and dyna~iclifting power, changes in the dlrec- tion and velocity of the rind, ternperat~~reva,riation.s 2nd the ~eightingof the airship with precipitations of rain or snow) differed for every trip. Often the desired altitude could be rea-chea only after throwing o~erboarda portion of the ~nun'itionsor fuel carried in cens. - Table - Airship i G~S I Date Object of raid / 1 capacity of 1 C~ew F~el i cu.m. raid i kg. -- 19500 9/9/14 mssian camn , at Insterbarg i i I Sach s en 20870 / 9/2/14 Antwerp I 11 1 1600 I 1 22500 1 8/21/14 Antwerp 13 2270 z9 I I Z 10 22500 1 3/20/15 Paris 12 2440 3/17/15 Paris, Galals 15 2605 1 5/16/15 Calais 14 1970 I Z 12 25000 i 7/22/15 I Malkin . 11 1350 1 8/11/15 Bialystok 11 1420 I LZ 35 22500 3/20/15 Pari s 11 2555 I 38 32000 1 4/29/15 Harwich, Inswich 14 3200 ! 5/31/15 London 12 3080

39 25000 12/17/15 Ro ma 13 2850 I 14 3060 74 32000 I Londoil 77 32000 2/1/16 1 Paris 13 2050 I 79 32000 1/31/16 Paris 12 2820 16 3440 85 ' 32000 1/31/16 Saloniki 86 32000 4/2/16 Minsk 15 2400 14 3550 90 32000 . 3/31/16 Normi ch Table (~ont. )

Airship ' iiater Bombs I Altitude Maximum I Distance ballast iI of I ::. j . .. . attack altitude f lovm 1 kg. kg. -a. m. h. : 7. 4 1950 900 2100 2515 365 ~achsen 1625 950 1950. 2500 661 . . I 2 9 1320 1750 2000 240C 562 Z 10 2720 995 2000 2400 433 2080 3009 2200 2675 708 3380 1600 3050 3150 450 Z 12 3480 1650 30CO 3300 491 3300 2000 - 3000 3600 608 LZ 35 1 2810 818 1 2000 2450 760 ! 38 4200 2 447 3200 3550 800 ' 6620 1357 3300 685 i! 39 3000 975 2000 22003900 478 I1 74 4050 2000 3 100 3530 1 1063 77 7100 2600 2900 3500 900 79 7100 1500 3100 3900 780 85 6090 2000 2900 3900 1425 86 6300 2060 2750 3500 600 2450 2500 3275 I As already mentioned, the 32000 cu.m (1130080 cu.ft) airships . met the. requirements until the spring of 1916. The constantly improving enemy defense in the west, honever, compelled the airships

to seek higher altitudes of about 3500 m (11483 ft). As shown by the above table, the 32000 cu-m- ships mere able to do this, but sy:- - 73 -

onlv a.fter t'n-sov~ingover some of tndir 1ca.d. In oPder to rfach thcs<:- zltLixdea, even before the ratds, it was necessary to 3uild still I larger airships. nihis mas dniie Sy addiiq -i;w rim 5 ET 10 m (15.4 cr . 32.8 ft) sections, one Setne~rithe tom 2or~zsi.d cai- a& tne oA;her 1 bstvreen the rear car aqd ths stern. This gare a gas cqacitg of 35800 cu.n with a tots; length of 178.5 m (585.6 ft) (most of the hangazs having a utiliezbls length of 184 m (603.7 f t) ) . The increase of about 2500 kg (5511.6 ~b)ic carzying capacity enabled t3e attainment of about 700 meters higher zltitude. Since the distmce between the tro cars rerriaiiled the saine, the hsary stern load was diminished by the increase in length toward the rear. The Navy acwired five airships of this t-j-pe .a116 the Army sever. Dxring 1916, the gas ca.paclty of six 32000 cu.m (1130089 cu.ftj airships, in the possession of the Army, was increased to 35800 cu-m (1264277 cu. f t). At the same time the individual parts were continually being improved. E:rternally the airships were made darker, thereby rendering them less easy to locate mith searchlights. They were painted gray with spots in imitation of clouds mith the avoidance of all brig>: parts on the cars. Many efforts mere made to lessen the noise, 'out without much success. ;Airships, even more tban airplanes, made

themselves known by their noise while still a long way off, thus rendering it easy for enemy listening posts to dis'cover them In the night sky by means of searchlights. The rattling and singing cf the - driving gear was considerzbly lessened, bvt not the noise made by the propeller. Some further reduction in the noise mas accomplished by ir~provingthe exhaust manif~lds,but no way was found to greveiit tliz hull ltself froi-a taking up the vlbratio-ns and acting in sone soi-t like a dr7m. The inc~easirignuaber of enemy a-;riators neceseitate.3 the best posgible armament. Two or three nac'nine gins were ii~s%all- ed on the top glatforrn in order to increase the firing field, m;.lic$ nab, hovever, O~E-tructedin the rear by the rudders and ~ta~billzing surfaces. The guns 5-r- the cars vere rotatzble, so as to be abie to fire in all directions. Their firing field Tas, however, obstructed above by the hull, tovard the rear by the propeller, and torard tl~e front by the suspension czbles, and or, the rear car also by the lateral driving shafts. In attacking an airship, airplanes usually approached from the rear, Taus rendering the armiag of the .stern desirable. It mas not pra.ctlczble to build a second platform on top and nearer the stera, on a.ccoimt of its meignt and the danger from gas, so that it, mas decided to install a machine gun inside the stern. In order to make escape possible in case the airship took fire, each member of tine crey ms provided ni th a pa.rachut e, vhicfn was attached outaide the car or to the top platfo~m. Then captive balloons were shot down, the oSserver saved hirflself i~ nearly every in- stance. On airships, ho~ever,full advantage ivas not taken of them, because the commanders frequently dispensed with then on account of the additional weight. The bomb-dropping device, trihich was at first very primitive and had to be operated by pulling on a wire, was now arranged +a be operated by electricity from the pilot car. Here mas a switchboard with Tnk?icfi all the bomb releases were connected, so that the off5cl2:: in ehc?rge of the bomls-dropping could ?elease, by pressing an electr-i.~ but%on, as many bombs as he considered desirable, Oil the %asis of observations made through a spyglass hangirg near the s;vitcKaxird. The actual release of a bomb mas indicated. by the flasbii~gor ex- tinguishing of a sinall glow lamp on the sxi tch'coard. Altogether, bomb releases mere provided, along the walk-yay between the tnc cars, for 100 light inczn5iai.y boinbs and 50 hea,vy explosive bombs. Furthermore, airships vere given, th~oughthe remarkable d-svel- opment of radiotelegraphy, aid which t5ey could no longer dispense with. Even before the mr, all airships mere equipped with radio instruments. At the o~tbreakof the vzr, h~-~~ever,t3ey were for the most part removed, in order to save weight. The Nzvy, however, continued to use them. In 1915, when the airship raids first included several airships, did the Army airship again feel the need of radio instrumsnts. T3e i~portanceof having thein on 'ooard had come to be recognized through the' experiences of the Mavy airships, ~mhic'ohad continually &ept in touch with the central station, from mhich they received timely warnings of changes in the veather andl changes in their orders, and to which they could impart their o:m views and wishes. In the meanwhile, lighter radio ixstrui-lents had been in- vented, with which it m,s possible to transmit messages to a distance of 1000 km (621.4 mi. ) and to receive signals from radio stations several thousand kiloneters away.

A distinct advance for airships was marked by the invention of the so-called " radio-compass, with mhich it was- possible to determine the 1oca.tion of the airship tvnen, dxe to fog or 103-lying

clouds, the earth vas invisible or ~hsn,2.s it sometimes happened, tl-ie enemy darkened their villages and rail-way lines. The ai-sl:ig then gave several radio signals from which %he receiving radio-compass stations determined its locatioa and communicated it to the airship. The disadvantage of this rnethhod was th2.t it also enabled the enemy radio-compass stations to locate the airship. The loss of th-e LZ 77 at Revigny mas largely due to this fact. On the may to its goal, the airship had to signal quite often for its low- tion, thus enabling the enemy to follo~its course and destroy it by adopting defensive rneamres at the right time. It mas only toward the end of the mar that the difficult problem of install-ing radic-compasses on airships was solved, thus enabling the reverse process to be followed, in vhich the airship gave no sipals, but

simply received signals given out by certain ground radio stations - at stated intervals, and then determined its own iocation from the data thus obtained. In spite of all the improvements, the 35800 cu-.in type fell short of the demands made upon it during the year 1916, although it met with some success. The difficulty of operating over the sea constantly increa.sed, due to the appearance of nunerous enemy wbma- rines and the development of seaplanes which took off over German waters from so-called llrnother-ships". Airships had been especially - successful over the sea. Whenever. the weather ms at all suitable,

- there mere always several airships engaged in observing enemy mar- craft. These airships sometimes remained in the air for 30 hours at a ti~e,patrolling the 3lorth.Sea from the Englis3 Chalznel an6 i;??

ccast of England to Ncrnay, and thus protecting ths Gsfmsn coast,

against surprise attacks. The air sliips co~.ld~IEC wizt~i~ the er~criy

mine layers and give warni~gsby rad?~. AlrsliZps Inere rwre S~~~C.C~SS.- ful t'mn airplanes in searchiizg for ~ines,becau.sa, by slackening tkeii. speed., thzy could remain lcnger over the mi~efield and tb~s

deternine the positio-n of the mines more accilrately. This work maae it co~pulsoryto remain at a lorn altitude and the heavy load re-

qcired 0i1 long observation trips did not alzays leave it possible,

on the sudden appearance of s~zbmarlnesand airplanes, tc ssek safety

. in altitude. The diff icultf es encoilntered during a raid have already been referred to. repeatedly. The defense, by means of anti-aircraft guns,

incendi~rybullets, searchlights and airplanes wzs SO stroiig and so well coordinated that .it was a miracle for an airship to escape. UnLess the employment of airships %as to be utterly abandoned, there mas no other course open but to increase their gas capacity again. It zould have been technically posskble to increase the length of the last type still further, but this mould ha-re been only a temporary makeshist which vould soon hzve beeii rendered use- less by the furtiper development of the enemy aircraft defense.

The Wavy, for which the presence, of utilizable airships mas

vital, decided therefore on the construction of an entirely nex typ,

. which, hornever, on account of its larger dimensions, could not be housed in the existing hangars. Hand in 'nand therefore with the preparations for building the new airships, there were built at most of the naval airship po'rts, nen hangars 24C rn (787.4 f t) 107;:;

. by 35 m (114.8 ft) high and 40 to 60 m (131 to 196.E f t) ~ide. The Army mas likexise in.terested in the fcrt'ner 'de~;-el9~;^:ler,tof ai~ships,tho~zgh not so much as the Navy, since in land f igbt'lng they could only be employed lor making raids. With the extraordi- nary development of aerial ~eapons,tnere seemed, fioreover, to be a prospect that, with the definite abandonment of -the airship, its tasks time, by the airplane. For this reason, the mr depa,rtmsnt built aikship hangars of the above dimensions only to a lhiteci extent and ad-opted an attitude of watchful maiting in regard to the adoption of the new -type of airship. The first airship of the type, L 30 (LZ 62j, was finished

, - the last of May, 1916. It had a length of 198 m (649.6 ft), a diarn- ---- eter of 23.9 m (78.4 ft) (a,n increase of 5 n; (16.4 ft) over that of preaious airships) and a gas capacity of 55000 cu.m (1942325 cu.ft). Externally it was noticeable for its favorable sha2e (with its blunt

nose and slender pointed stern resembling the ~chfitte-~anzairship), , which had been found, as the result of years of sciertific investi- gation, to offez. the least resistance to the air. The cylindrical

portion, ~hichin previous shfps tpas longer than the distance be- .

tween the cars, was only 35 m (114.8 f t) long. In this connection, the main advantage of the former type, namely the employment of a

. large number of similar cells and the rapid quantity pro6uction of the transverse frames or rings, was relinquished in favor of grea3er speed - The frame was strengthened by using thlcicer metal and esp:?c1:~-..3. --, ', . - by internal bracing of the main trensverse fraass. The r3dg;: gi-idsr

. . a.ild walk-way girders vfeTe likemi sz str engtt e:?ed. An i.?&;c*-i:. a-~:.-c.?~.;;a::

edded in the form of a central cable ~u2~1irrgthe ~~5~1sLezg'i;h of i:li? airship from tip to stern through he g%s c213.s and firxly 2tt;ackZii

to 2.11 the transverse 'fzamesu With uneq-ua.lly filler5 gas cells axfi

braces of the trailsverse frallies and resulting rqlxres rere 'G~JS avoided. In all there were 19 gas cells varyimlg in capa,city froiil 375 Lo 4:L50 cu~m("1.3243 to 146557 cu.ft) . Each cell was pro-~ldedat the

top with an outlet tu5e. Nine cells mere provirl?ed mi-i;> outlet valves, which could be operated from the f'ory;ard car. Each cell was

provided nea-i. the bottom with two safety valves through which a ?Or- tion of the gas could escape whenever its tension became too great, - due to a decrease in the -atmospheric presswe or a rise in tempera- tUre= In former airships the gas then esca~edsLomly into ths a*- masphere through the po~ousouter envelope. After the outer envelope, however, had nox been covered nith dope for the purpose of reducing the drag and was consequently no longer porous, the gas had to be conducted into the outer atmosphere through ventilating shafts installed between the gas cel-1s. This arrangement had the disedvant- age .that the gas, escaping in greater quantities from these shafts, forned an explosive mixture with the air and became a source of Czn- ger, although not so great as that of the envelope of e-~losivegas formed around the gas cells in former airships. Instead of four, there were nov s5.x 240 HIP engines in fsv-r cars, three of them in the Tear car, one in the forflard car %nil 5~:: . . in each of the side cars. The: engixra ae-r-2 irsl;t;>teJ :jn e:icyac-;i; supports, so as to make i"l;~~rf!curs: tc: a~;>rkon c~s:.~lrss~a;:.

In the rear car, the power of -i;tvo engi~eaiL?i>~i~;& zLbrsm't was trazs-. mitted in the fo~merriierinez: by means of Ss5i;lar skafJ~s%o lateral propellers rounte& oil brackets. These pr~pelle~scctl.19 be r!.;versec'L. All the -other engines cirove propellers at, the rear end of tliz csrs. The speed attained, vith all six engines running, nas about 28 m/sec (91.9 ft%sec), the increase being due partly to the increase i.n engine pomer and partly to the iripro~edshape of the airship", The side cars mere each reached by a ladSer from a passage-way leading from the main walk-way. They were very s;;lall arid only af- forded. room for the necessary engineers znd the machine-gzln operator. With the increased gas capacity of the airship, the ca6acity of both the normal and the tr%~xingballast bags mas also increased.

There were 14 of the former, mith a capacity of 1000 liters (35.3

cu-ft, 264.2 gal) each, and 8 of the latter raith a capacity of 250 liters (8.8 cu.ft, 66 gal) each. There were 8 fuel tanks holding 670 liters (23.65 cu.ft, 177 el) each, an& 32 holding 290 liters (10.24 cu.ft) each, it being possible to thyow J~helatter overboard. The first 55000 cu.m (194.2325 cu. ft) airships bad hardly reached the front hen new difficulties arose. The sapplying of eneiny aviators mith phosphorous projectiles gave them a weapon a~~lnst which there ras no protection for the airship. It mauld me been possible to surround the gas cells with a layer of nitrogen, but this would have necessitated a considerable increase iil the size oi the zirshtp. The increasing difficulty of 3an6lizg an airshlp on the grou~dformed ar_ obstaclz to such an i;;lc~ea.s6. Already marly days of otherwise favorable weather had to 5e wasted, aerely be?=ause a moderate mind mas blaming In a direcf'ion rrrifavc~rablefor re~ovlng - the airship from its haiigar. ~ltl~ou~hof great velue for the rey- lar operation of large airships, there viere no revolving hangars ex- cepting the one begun in Nord'iolz by the Navy just before the mar. It istrue the var 8epartnzn.t began t~orevolving hangars in Diissel- dorf and ~chneidedhlin 1916, but work on them vas socn discontinued, when it mas found .that airships were conti:~~allybecoaing less important as instruments of mar. After the acioption 02 phosphorous pro J ec.tlies there remaizied nothing else to do, if airships were not to be dispensed vri.th en- . tirely or still greater difficulties experienced in handling them on the ground, except to build lighter ones of the same size capable ofaattaining h.igher altituces than could 5e reached by airplanes in their state of development at that time. The war department saw .in this attempt only a passing improvement and held the opinion that thc

airship tasks could be performed by large airplanes. It did not, however, give up airships entirely, but ordered no new ones and sent the old ones only where the weak defense rendered swcess probable. It was otherwise with the Navy, for which t3e retention of airships was vital. It was therefore obliged to find a my, at a91 haz- ards, to maintain the vitality of airships. The sixth engine was first dispensed with, for the sake of attaining a higher cruising altitude. This step only slightly reduced the speed, due to the fact

that '~h.e loss in poTer ims off set by improvrng the shape of tile cazs

and elimii~atingall urlneceseary drag. The IGSSof 2~ eillgiine ms a disadvantage as regai.ds,s~reasss of fun~tioniizg,Sut confidence in tine reliability of She Uay5ach en5ines cc~lddiggel any appreheneioz. The sixth engfne mas left out cf the rear car. The two engines

remaining in this car vere So th connectsd mlth a propell.er of larger. ' . diameter at 'the rear e;ld of the car.. ?he lateral propellers were removed, togethe? ai th the brackets and t-~h~larshafts, thereby. considerably diminishing %he drag. The othw pornas. plants rema-ined un-

chenged, excepti~gthat reversjing gears f 0-1 go iag ba.c!:~~~rdwere, installed in the sfae cars.

A further lightening pras effected' by reducing the ~urfiberof gas - cells from 19 to 14, and inc;reasingr their capacity. This ka,d the disadvantage that sornetimes, -.vhen a la.rge cell Fas daraged, the loss in lift mas so large that it could be off set nelther by rol-easing ballast nor aerodyna-ically and cotlild co-nseqilen"tly no loilger remain in the air. Furthemore, defensive amament aas ogitted, at least on raids. The omissfon of all the machine-guns with their shf elds; ammunition and spare parts effect,ed a considescible sa.ving in weight, though dearly boug3-t. A1tho:lgh there-was hardly any chance thzt an ever-so-vell-armed airship could protect it self in the night, since the airplanes were usually invisible, t3e airshi? might at damn en- - cgunter hostile airplanes against nhich it mould have been able ,to defend itself. The importance, however, cf havicg the airsh9p s~c- ceed in its main object led to.the policy of seeking safety only at altitud-es unattainable by ~irplanes. Here the airship was safe and needed no arnament . Lt was possible to llgh-te-n zn airship i-r, still oi;he?r ways, namely, by rerooving same of the bomb releases rendered nnceczssarj.- by the

snal ler number of heavier boa3s carri ed, by remving all parts z: : "- not absolutely necessary for a raid, r.educ;fng'the size of the rear car and the weight of all structural parts, thus contiaually rncreas- ing the attainable altitude of su-ccessive airships. They were thus

enabled to attain an altitude of 5400 to 6000 m (17'7i6 -Lo 19585 ft) , with a crew of 20, fuel for a ten-bur return trkp and 2000 kg of b01n5~.

All these measures helped the 1Ja.v~airships to fur-!;her successes and to a reduction of the ever great losses when making raid-s. The fears of the War Departinent mere unfortunately con? irmec in the course of time. Enemy afrplsnes developed rapidly and were soon able to reach the highest altitudes attained by the airships. The Army accordingly desisted from the further employment of airships. The

, Navy, however; contin~edto use them, though ma.i~rlyfor observation and only occasionally for raids.

. The hundred-hour observation flight of a 55000 cu.m (1942325 cu. ft) airship (the LZ 120), over the Baltic Sea in the sumel. of 1917, demonstrated the availability of airships as a means of trans-

portation to distant lands which, on accoun-t of the war; could be , reached in -no other way. It was accordingly decided to carry help to the hard-pressed African garrison, in the form of mackine-ps, ammunition and medicaments. By the addition of 30 m (98.4 ft) in length and tm sore @s cells to the 55000 cu.m type, it was given a carry!.ng capacity of

50 metric tons (110231 lbs), so that it yas able to carry i2 tons of freight in acldition to fuel Tor 120 hours.

The L 59 left ~tim~olill ~~ungary,Noveinher 21, 1'317, and reached There, after it had- ' the vicinity of Kharb~m--.ina day znd a talf. covered more than half of he distance to East Africa, it received a radio order from the Na-ae~station to return, because, accordirtg to information shich had. been received in Berlin, the situ~tionof Let tom Vorbeck was considered hopeless. As su3sequently discovered, the report was exa.ggerated, making it all the more regretiable that such a brilliant voyage should 5e interrup%ed in this raaaer. The moral effect on the who13 rorld could not be +,oo nighly estimated,

even if the L 59 had arrived too late. The perfora;.,nce of the airship can, nevertheless, be properly estimated. It had covercd 6800 kilometers (4225 miles) in a nnn-stop fiTght of 95 hcurs. After

landing, there was enough fugl left on board '60 enable %he airship to fly two days longer at a diminished speed.

The airships LZ 120 and L 59 thus made tro ygorld records In 1917, as regards both duration and length of voyzge. These brilliant ex- ploits were not surpassed even by the American t~ipof the English airship R 34 in 1919, although the voyage of the L 50 mas nade under difficult conditions during the war, while that of the R 34 wzs made only after the most thorough preparation and with all possible aid from radiotelegraphy and the weather bureau. During the minter of 1917-18, another important improvement ws made. It had been found that the airships lost speed at hi@ altitudes, due to the strong rcinds and to the loss in engine power resulting from the decrease in the density of the air. These disad- vanJ~ageswere elirninated by the incention ofthe laybach high-altitude engine, mhich first developed its full pcmr in rarefied air. The year 1918 again gave the Zeppelin Airship Constr-~ctionCorn- pan7 the task of buildlng a larger? type, since the enemy anti- aircraft guns were constantly becoming more efficient and enemy airplanes were tirelessly attajning the flight altit,udes of the airships. The larger airships, fzom the L 70 on, showed an increase in fligilt altitud-e of about 600 mete~s(1968.5 feet) up to a ceiling of about 6500 meters (21325 feet). But even this was not enough, for the L 70 vas shot down oa its first raid. In order to reach the altitude

.. of 8000 meters, it was necessary to build a nerr t;rpe of greater diam- cu . eter, with 10 engines and 100000 cu.m (2%47/ft) gas capacity. During . / these undertakings, Captain Strasser, the chief of the naval airship service, met a hero's death on the L 70. With him the naval airship

service lost its most zealous advocate and the outlook 7.m~very dark regarding the further development of naval airships as instruments of nar, when the re~olutionbroke out.

The fate of the remaining Zeppelin airships is well knovm. The

LZ 113 and L 72 were turned over to Fgance, the L 64 and L 71 to England, the L 61 and LZ 120 to Italy. The L 30 ms dismantled as obsolete. The L 37 mas taken apart and sent to Japan. For the airships L 41, 42, 52, 56, 63 and 65, destroyed in their hangars by the -92-

1,Ta.v~personnel in the suminer of 1919, the allied countries deinend reimbursement. 'D;%ether in noney or in substitute airships or in

some other may, will soon be decided in the differe~tcountries.

. Even though the outcome of the nar left no hone for the reten-

tion of military airships, it did seem at first th&t the Entente mould have no objection tc a restricted air traffic. Ia the spring of 1913, the Zeppelin Airship Construction Company accordingly began

the construcfiori of a comercia1 airship, yith which the German Air- ' ship Company (~eatsche~eftschiffahrts-~ktiengesel-lschaf t) intended to inaugurate a trial service, in order sllSsequenlly, on the basis of the experience obtained, to add. further airships and open up air traffic lines even beyond the boundaries of Germany. The' performa~cesof the IIBoden~ee~~were really astotlnding. The small size of the airship, 120 m (393.7 ft) long, reminded one of _ the first Zeppelins. With a gas capacity of only 20000 cu.m (706300 cu. ft), it had a carrying capacity of about 10000 kg (2?046'.1bs)a.+? - (With the same gas capacity, the Hansa' had a mrryiilg capacity of only 6000 kg (13228 lbs). Four engines gave the airship a speed of 130 km/hr (80-8 rni/hr). he Eansa had a speed of only ?*, lan (43.5 mi) with three engines. ) me fullest adventage mas taken of every- thing that was lea.med during the war, even to the smallest details.

The shape and disposition of the cars md rudders, valk-vay and Wmer transmisgion were copies from the rast recent airships. The passen- - ger .cabin was placed in immediate connection with the control car. It had room for 20 persons znd was provided vith every coiqvenience, including a heating plant. During the period from Aug~~.st24, to Decernber 1, 1919 (98 cal-- endar d-ays) , t5e Bodensee i~ade103 trips, amounting to 52060 kn!

(32311 mi), in 532 hours. 73 trips were m&de betwssn Friedrichshafeg and Staaken neaz Berlin. The following table conpares the perform- ance~ofthe 3odensee viith those of the earlier passenger airships.

Table

I .N8rne of airship, Gate of i 1V1irr1b e r o f 1, first flight 1 da~si;~se~vice Deutschland 6/19/10 to 6/28/10

Ersatz Deutsch- 3/23/11 If 5/16/11 land Schwaben 6/26/11 6/28/12

. Viktoria-Luise 1 2/16/12 7/31/14. 1 , 1244 Hansa Sach s en Bodensee 1 8/24/19 12/1/19 98 , I Table (~ont.) ~eutschland Number of Number of Eours Kilonetsrs\. Passengers days trips I flown flom Deut schland 5 7 20.30 z&?? LZ 6 18 34 66.11 3132

Ersatz Deutsch- 17 - 22 47.11 2379 129 land schwaben 1 143 218 473.32 27321 1553 - ~iktorla-Luis? 316 . 489 981.17 54312 2995

- Hansa 25'5 399 '840.37 44437 . 2187 Sach s en 233 419 740.57 39919 2465 ~odensee 103 - 532.00 52000 2253 - 9,g - . . In Dec~nber, 1919, the Rodensee was lengthened_ ..l0.metsrc (32-8

f?et), and.given a gas.zapacity of 22250 cu.m (785759 c~.ft). The mdmber of gas cells was ihczeased from 11 to 12 and the ca?2j7ing capacity from 10000 to 11000 kg (22046 to 2U59 I~E)~Ths Bozensee

now Cad the ssme dimensions as the "No~dste~n"(~orth Sta.r) built in- October to December, 19i9. With these two airships, carrying- 30 passengers each, it was intended to open an airship line in the spring of 1920, 'oeJ~weenSmitzerland and Stockholm, by way of Serlin- The Entente, however, refused their perriission and .both airships

are still lying inactive i.11 their hangars. Their fate has also been decided by the latest disarmament note: They .mnv.st be turned over to the Allies and when these lines appear, the Bordsfern will V have already landed in France.

Translated by C National Advisory Committee for - Aeronautics.