DESIGN ANALYSIS OF Messerschmitt Me-262 Jet Fighter

PART 1 ― THE AIRFRAME

By JOHN FOSTER, JR., Managing Editor, “Aviation” This first detailed engineering study of Germany's top jet propelled fighter ― the 15th in our series ― reveals many unorthodox design and construction features and shows the importance of the production engineer in its development.

ERMANY'S MOST SUCCESSFUL 11 ft. 4­in. over­all height, it was serving as a jacking point. Then jet propelled plane, the Me­ used as a fighter, fighter­bomber, follows a 14½­in. section enclosing G262, is an unusual and ground attack craft, and was a flush­riveted channel­shaped combination of radical and orthodox apparently also designed for photo former, the whole being screwed to design, materials combinations, and reconnaissance use. the next section which contains the workmanship, some of the latter The very tip of the fuselage looks nose wheel and the four 30­mm. being surprisingly sloppy. It shows, exactly like a propeller spinner – MK­108 cannon grouped high in the too, that the production engineer and may well be just that – with a nose section. had as important a place in its hole cut in front so that a gun Since the length of these guns is development as anyone connected camera mounted inside, reached by but 3 ft. 6 in., a very compact with the project. a small, quickly removable access installation has been achieved with A low­wing monoplane of 40 ft. plate set in the left side. A solid no external projections. A large 11½ in. span, 34 ft. 9­in. length, and web bulkhead backs this section up, spherical support around the barrel

JL McClellan: Me-262 Copyright 2005 p 1 of 40 JL McClellan: Me-262 Copyright 2005 p 2 of 40 Exploded view of Me-262 showing major components near the aft end facilitates mounted high, the use of steel in employment of steel was dictated by adjustments during sighting in that section is understandable transportation difficulties rather than operations. because of the blast effect, but even design considerations or lack of The guns are usually set to the belly skin is of the same aluminum, for reports emanating converge at 450 meters. The MK­ material. It is possible the from Germany indicate that the 108 fires 575 – 600 rounds per min. with a muzzle velocity of 1,570 fps., and weighs bu 134 lb. Compressed air for charging is carried in eight bottles set inside the fuselage on the left ahead of the cockpit. The two top guns carry 100 rounds each, the bottom pair 80 each, and all are fired simultaneously by a switch on the contact stick. Although the 262 was designed as an interceptor, Hitler ordered it made into a bomber. The result was installation of two jettisonable bomb racks, each carrying one 550­lb. bomb. Additional armament on later models consisted of 24 R4M 5­cm. rockets, 12 under each wing, and it is reported that the Germans planned to install up to 48 under each wing. Skin of the 6 ft. 5½­in. long section aft of the spinner is .080 Phantom view showing installation of gun camera in nose, four 30-mm. MK-108 cannon, sheet steel. Since the cannon are with ejector shutes below, and electrical connections for firing.

JL McClellan: Me-262 Copyright 2005 p 3 of 40 steel may have been a deciding factor. The cannon are most accessible, for two 35¼ in. long access doors, piano hinged 1½ in. off the top centerline, can be quickly opened simply by loosening two flush toggle latches like those used on cowling of the FW­190 (see page 131 Oct. 1944 AVIATION) exposing all the gun mechanism as well as the ammunition drums. This whole nose section attaches to the mid­fuselage in a simple but effective manner. At each lower corner is a 1­in. )approx.) high­ tension steel bolt fastening it to the solid web bulkhead of the mid­ Closeup of left gun compartment, showing access panel in raised position. Note section. At the top, some 6 in. from turnbuckle tie rod at top; it makes one of four points at which complete nose section is the centerline, are two 1­1/2­in. steel attached to bulkhead at right. tubes, also bolted to forged fittings on the mid­section bulkhead and Nazis were not pressed at any time extending forward to the bulkhead at for this material. However, since the front end of the gun access the nose section carried both the doors. Both these tubes are built as heavy armament and the nose turnbuckles so that alignment wheel, the added strength of the adjustments can be easily made.

Hitler ordered Me-262 used as bomber, even though it had been designed as interceptor, View from below fuselage connection, so two types of bomb racks were developed. Type A is at top, showing: Forward showing how through-bolt ─ one on each suspension point (A); forward bulkhead (B); three-point connection to fuzing arm (C); side ─ joins nose to mid-fuselage section. power lead to fuzing arm (D); bomb releas slip (E); aft suspension points (F); power lead After connection is complete, access holes to release circuit (G); mechanical jettison rod (H); charging head (I); adjustable crutch (J); are covered with doped fabric. At top is suspension hook (K); and charging head (L). Type B (bottom) shows fprward suspension one of quick fasteners by which cowling point (A); crutch ratchet (B); power lead to fuzing arm (C); aft suspension points (D); lead over gun compartment is held in place. to fuzing arm (E); crutch ratchet (F); charging heads (G); and suspension hook (H).

JL McClellan: Me-262 Copyright 2005 p 4 of 40 Phantom view showing cylindrical-section cockpit in fuselage. This “liner” section is designed for pressurization, but craft and reports studied reveal Nazis did not actually pressurize Me-262 in operation.

Thus it would be possible for a trained crew to change a damaged nose section in the field in short order, or it would be a simple matter to install a nose equipped with different armament or photo recon units. At the end of the nose section, the Me­262's fuselage cross section is practically an equilateral triangle, only slightly rounded out. First bulkhead in the mid­fuselage section is solid web aluminum alloy with six vertical and two horizontal hat shaped stiffeners. At a point 16¾ in. back is a channel shaped former, flush riveted to the skin, and 16 in. farther aft is another solid web bulkhead, with vertical and horizontal hat shaped stiffeners. Practically all the space between the two solid bulkheads is taken up by the fore fuel cell (which will be discussed in detail in the section devoted to the fuel system). The bottom panel of this section consists of a waffle grid, double stressed skin, 34¾in. long and 55 in. wide. The panel is attached to the fuselage by flush screws and captured nuts, the same system employed on the FW­190 panel beneath the fuel cells. Interchangeability of these panels evidently was not much of consideration in Me­262 production, for the screws were set approximately 1¾ in. apart but with variations of as much as ¼ in. and Detail sketch of cockpit canopy, showing jettison lever on pilot's right and locking lever considerable misalignment. at his left. Front windshield panel is 3½-in. thick bullet-proof glass. No side or bottom Every Nazi pilot apparently was armor protection is provided. his own Führer, for the Germans call the next section the Führerraum, or pilot space. And they must have been little Führers, for the rudder pedals are quite close to the seat and there is no fore­and­aft adjustment

Me-262 canopy open, showing jettison lever and cable at pilot's right. note curved sil- houette armor plate which fits over pilot's head. Evidently, this was modification of original design, for basic plans show n such installation. At windshield base at left can be seen cockpit ventilating scoop. Apparently, this was also a last-minute modification, one which showed workmanship far below German standards.

JL McClellan: Me-262 Copyright 2005 p 5 of 40 Main instrument panel with flight instruments,at left, engine instruments at right and bomb switches on panel at lower center. Note how gunsight at top has been swung to right out of way for landing and takeoff. Engine instruments, from top to bottom are: Tachometers, gas temperature gages, lube oil pressure gages, and fuel supply inidicator. Original design called for installation of gas pressure gages, also fuel injection pressure gages alongside oil pressure gages.

Left side of cockpit showing, on diagonal panel: Oxygen flow indicator, emergency landing gear and flap operating switches and oxygen valve. On horizontal panel, from front to rear, are: Landing gear and flap position indicators, landing gear and flap operatging buttons, stabilizer pitch indicator and operating switch, throttle quadrant, and (not in photo) fuel selector valves, rudder trim tab crank, and jet assisted takeoff unit jettison release. At base of front panel can be seen pull handle for nose wheel brake, and at right, beneath left windshield panel, is lever to open or close cockpit ventilating scoop.

Right side of cockpit showind, at wisdshield base, canopy jettison lever below which are, from left to right: Pilot heater, Very signal, radio frequendy selector and on/off switches, and tachometer low-speed selector switches. Curved handle in fuselage side is bomb release. Pulling it clear back beyond bomb release stop jettisons bomb racks.

JL McClellan: Me-262 Copyright 2005 p 6 of 40 Phantom view showing two main 238-gal. fuel tanks just fore and or from aft to fore tank. A 53-gal. reserve tank can be installed aft of cockpit. Each tank is fitted with two booster pumps, and below cockpit, and Nazis had plans for an additional tank to go selector valves permit pumping from either tank to either engine, behind aft unit, with approximately half its capacity.

Inside aft fuselage, with radio in laeft foreground, are seen master section are integral part of wkin sheets, which are joggeled to compass in center, oxygen bottles at top, and elevator, rudder, thickness of metal for lap hoint, then bent inwrd to make “J” or and rudder trim tab torque tubes at right. Shown are typical channel section.. stringers which completely replace longerons. Formers in this JL McClellan: Me-262 Copyright 2005 p 7 of 40 either on the pedals or the seat. An average sized American sitting in the cockpit finds his knees sticking well up in the air right in front of some of the instruments. Only one channel­shaped former extends form the cockpit rail to the bottom of the fuselage at the cockpit which is, in effect, a horizontally­ disposed cylindrical section with part of the wall sliced off. This “cockpit liner” section was designed for pressurization, but the craft examined had no means of developing pressure and there are no reports of any of the 262's actually operating in combat with pressurization. Further evidence that cockpit pressure was an unused design feature is found in the windshield, a conventional three­piece flat­plate unit in which the front piece is 3½­ in. bullet proof glass, set in a steel frame, but merely screwed in without the usual synthetic rubber mounting found in other German craft. The seal – which certainly Exploded view showing construction of does not appear to be designed for empennage. In assembling Me-262, pressure – appears to be plastic stabilizer is put in place, then vertical fin designed only to prevent normal air is bolted to aft fuselage section. leakage. The cockpit canopy consists of two rounded plastic glass sections mounted in a frame with flat fore­ and­aft pieces and tubular base. It pivots on th right side for entrance and exit, and it can be locked closed only from the inside by a lever

Closeup of stabilizer adjusting motor and screw jack which is bolted to uper section of aft fuselage. Guides just above jack have slots to take retaining Overall view of empennage, showing installation of pins in leading edge of stabilizer fairing. stabilizer and its adjusting mechanism. A single-piece drawn aluminum fairing, held by 41 screws, encloses this unit.

JL McClellan: Me-262 Copyright 2005 p 8 of 40 Detailed photo of mass-balanced elevator trim tab, evidently origi- by gusset plates (shown at either end). Note that trailing edge of nally designed as servo unit but in actual practice riveted in place tab is neatly flush riveted, but elevator itself has ordinary rivets.

which drives pins into holes set in case on some late planes. The tachometers of two­speed variety to the base of the windshield frame and main instrument panel is divided in give readings from 0 – 3,000 rpm. the turtleback section. A 16­mm.­ two sections, with flight and form 2,000 – 15,000 rpm. thick head and shoulder silhouette instruments on the left, engine (generally red­lined at 8,900 rpm.); armor section, which extends up and instruments on the right. two gas pressure gages indicating up over the back of the pilot's head, is Flight instruments include: to 1 kg./cm.²; two gas temperature bolted to the canopy frame just Artificial horizon, combined with gages indicating up to 1,000 deg. C. ahead of the turtleback section. bank and turn indicator, airspeed (with marks on the gages at 680 Either the Germans changed their indicator (some of which have been deg.); two oil pressure gages; and own minds about instrumentation or red­lined at 658 mph.), altimeter, fuel gages for front and rear tanks. had them changed by Allied rate of climb indicator, repeater Called for in design plans, but not bombing, because original designs compass, and blind approach installed in craft studied, were two called for more instruments than are indicator. fuel injection pump pressure gages, actually installed – at least that's the Engine instruments include: Two marked at 65 kg./cm.².

Front face of main spar joint at centerline, showing flanges on tank can be installed just in front of spar, being held in position aluminum webs bolted together, and steel splice plates on top and through skin panel screwed to captured nuts (seen on lower bottom of both steel booms. This particular plane had been flown boom). without bolts through splice plates being safety wired. Reserve fuel

JL McClellan: Me-262 Copyright 2005 p 9 of 40 Just below the center of the main trim tab crank; and release cable to panel is the bomb switch panel, jettison rocket units for assisted marked for dive or level bombing takeoff. and for instantaneous or delayed A corresponding panel on the action fusing. pilot's right contains pitot heater Above the main panel is the switch; Very signal switches; radio gunsight, in most cases the old­ frequency selector and on/off fashioned REV1 16B reflector type, switches; starter switches for starting which can be swung to the right out motors; and switches to select low of the way for takeoff and landing. speed indicator on the tachometers. On a slanting panel just to the left The electric junction box is of the main board are valves for installed below these panels outside emergency operation of flaps and the fuselage cockpit liner, and it is landing gear; oxygen flow indicator; Phantom sketch showing method of easily accessible from the ground oxygen pressure gages (not on all attaching full length slot to guide which because it is located just above the planes); and oxygen valve. travels over gall bearing rollers bolted to wheel well. On a horizontal panel just below nose rib. Slots open automaticlaly at 186 At the base of the main panel on this unit are: Position indicators for mph. in gliding angle and at 279 mph. in the left is pull handle for the nose flap and landing gear, and buttons, climb. wheel brake, a unit evidently immediately aft for operating both installed to facilitate stopping on the these systems; stabilizer pitch indicator; stabilizer adjusting small turfed fields which the switch; fuel selector valves; rudder Germans were forced to use during the later stages of the war. Just under the windshield base frame, also on the left, is a pull lever to operate a small square air scoop set in the fuselage side. This apparently was a late factory modification – and the workmanship would certainly never have passed German inspection in the early days. The pilot's seat is adjustable only up and down on a parallelogram frame, and it is locked in position by a lever under the front of the seat which engages a pin in ratchet teeth. Unlike earlier German craft, the Me­ 262 has no bungee cord to facilitate moving the seat. The upholstered back of the seat is held in place by two clip springs to facilitate removal for access to the battery, which sits Detail showing inboard end of steel-skinned outer slot in open position. Note that just behind the seat frame. leading edge of wing is of angular shape, with rolled steel sheet riveted to it behind slot The seat itself does not to give proper airfoil. Inset shows slot in closed position. incorporate armor plating; this is, instead, attached to channel­shaped vertical and horizontal stiffeners riveted to the solid aluminum alloy bulkhead which begins the aft fuselage section and forms the front panel of the rear fuel cell space. The bottom skin panel for this section measures 35½ x 60 in. and is similar in construction to that under the front cells. In the middle of this fuel cell, some 17¼ in. back, is a former which is built­up double channel section up the sides to the second­ from­centerline stringer, from which Closeup showing wingtip and outboard end of slot in open position. Wingtip is attached it is single channel. This former, by bolt, which can be seen in access hole just behind formation light at spar line. A hori- like most others, has cutouts for the zontal pin inside leading edge and vertical plate fitting into yoke of auxiliary spar stringers. complete three-way tip attachment with use of but one bolt. Note roughness of weld In this connection it is interesting joining upper and lower skin sections of tip. to note that the Me­262 has no

JL McClellan: Me-262 Copyright 2005 p 10 of 40 longerons, employing only hat­ section stringers – one along the top centerline aft of the cockpit; five along the sides (with one ending at former 14); and five along the bottom (the two outermost ending at former 15). The bulkhead forming the ft end of the rear fuel cell is a solid web but is sheet steel of approximately . 080 gage. An unusual construction feature is found throughout much of the aft fuselage section, where the formers are made of the aluminum skin sheets themselves. In fabrication, the skin sheets are formed to the Exploded view of wingtip, two-section aileron and aileron trim tab. fuselage contour, then the aft ½ in. is joggled to the thickness of the metal itself – about .050 – then bent inward to form a channel or J­ section. The next skin is lap jointed and flush riveted in place. Whether this method of construction should be blamed or merely the type of labor available is not precisely known, but many of the joints were not at all clean, requiring the use of considerable filler to smooth them out. Careful study, however, seems to indicate it was probably more the quality of labor than the design, for many of the rivets were somewhat out of line and had required considerable filler themselves to give anything like a smooth finish. Immediately aft of the cockpit the fuselage shape starts its change to a very narrow elliptical section only 2 Aileron trim tab apparently was originally designed as servo unit, but in practice it turned ft. wide at a point just ahead of the out to be merely ground adjustable through turnbuckle tie rod shown connecting it with stabilizer. aileron control bracket. Note that trailing edge of tab has flush rivets while that of aileron Construction of the tail cone is, in itself uses conventional rivets to hold skin panels to flat strip. some respects, quite like that on the FW­190. It bolts to the aft fuselage section with the joint larded (at least on some planes) with liberal quantities of filler and covered by a doped fabric strip in a vain attempt to get a smooth surface. The former aft of the joint is a built­up ring riveted to a steel I­ beam section which slants aft 47 deg. from the vertical and extends up some 2 ft. above the fuselage top to form the lower part of the front fin spar. The end of the tail cone, 4 ft. 8¼

Right hand flaps in fully extended position – down 50 deg. Upper wing surface extends back over slots so that in extended position they are shrouded about 1½ in.

JL McClellan: Me-262 Copyright 2005 p 11 of 40 Phantom sketch showing how flaps are moved back and down. Closeup of right inboard flap in extended position showing toggle Hydraulically operated toggle at left forces flap back, but 7-in. with its adjusteing set screw. Note how one adjacent lower wing track (which is channel shaped) moves it down. Set screw in surface is attached by flat screws, probably to facilitate production toggle arm can be adjusted for upstop. as well as maintenance.

Phantom view of flap actuating system, stabil- izer adjustment, and rudder trim tab, with cross sectional detail showing operation of slots and flaps

JL McClellan: Me-262 Copyright 2005 p 12 of 40 in. aft of the former just mentioned, is a stamped flanged aluminum channel section member which also serves as the bottom of the rear fin spar and rudder post. Connecting the tops of these two spars is a horizontal stamped flanged channel member upon which the stabilizer is mounted. In production, the stabilizer must be installed before the fin and rudder are put in place. Then the fin, the spars of which have steel plates riveted to their lower ends, is attached to the tail cone by seven bolts along each side of the front spar and four on each side of the rear spar. In Wing-to-fuselage attachment inside left nose rib, showing bolt through fitting which is construction, the fin is built up in attached to bulkhead forming aft end of front main fuel cell. two halves, divided on the vertical plane of the fuselage axis. The Although the rudder is quite yokes attaching to the rudder false halves are then bolted together along deep, it has but two hinges, both spar, giving a universal joint effect. the spar line through access holes in typical self­aligning ball bearing The lower hinge is a vertical pin the skin. These holes – of units. The top bearing is set just extending up from a rudder rib. approximately 1 in. dia. – are then beneath the mass balance, the Trailing edge of the tab is formed by covered with small doped­fabric lower at the bottom rib, where crimping together the skins, around patches. The joint along the leading push­pull controls also attach. which a strip is folded and flush edge is covered by plywood fairing Oddly enough, the combination riveted. It is 36¾­in. deep, with 4­ which is screwed on. Rounded tip servo and trim tab has four hinges 7/16 in. chord at the top and 6 in. at of the fin is built in two halves, and, comparing its construction the bottom. welded together and attached to the with other parts of the plane, it As is the case with several other main body by flush screws. A sowed every evidence of having German planes, the 262's all metal single­sheet, deep­drawn aluminum come from a different shop. It too, stabilizer is adjustable, the incidence fairing is fastened by 41 flush has a mass balance, set right under being changed by a small electric screws to the base of the fin and top the top self­aligning ball bearing motor operating a screw jack of the fuselage. hinge. The two middle hinges are mounted inside the fin fairing on the Chord of the rudder is narrow, small metal blocks with vertical front face of the frame to which the being but 20½ in. at the widest pins holding them to the tab and vertical fin is bolted. This unit is point, but there is plenty of depth, for the rudder has an overall height of 6 ft. 11 in., extending from the top of the fin to the bottom of the tail cone. A small tip is screwed to the top just above the large mass balance, and the main section of the unit follows conventional construction practice. The spar is D­section, with the curved part fitting closely inside the fin trailing edge. Conventional stamped flanged aluminum ribs with lightening holes extend back to the trailing edge, where the skin surfaces are crimped together and riveted with 3/8­in. ordinary round­ head rivets. Fore part of the bottom portion of the rudder, beneath the lower hinge, is comprised of two formed sheets Principal wing-to-fuselage attachment is by 17 bolts through flanged member riveted to flush riveted to the spar and lowest top wing surface. On first Me-262 brought to America for tests, many of these holes rib. The aft portion containing the were elongated and some were as much as 1/16 in. out of line, so extra steel strip was formation light is made up of two added, holes being reamed to take ⅞-in. bolts. Angle bracket at left is anchor for fillet small formed sheets attached by flat cable which goes under slips seen riveted to horizontal part of flange. screws.

JL McClellan: Me-262 Copyright 2005 p 13 of 40 Exploded view of main landing gear and phantom sketch of wing showing position of landing gear torque box and whell well, Cut- away (right) shows main landing gear oleo strut with hinge bearings and wheel axle welded in place.

Closeup of right landing gear wheel showing double skin fairing and relative position of retracting jack. Tire is 840x300. Oleo strut toes in 4 deg. in extended position. Flap actuating piston can be seen on front face of main spar directly ahead of oleo. Lower wing surface (here removed) is attached by flush screws.

JL McClellan: Me-262 Copyright 2005 p 14 of 40 mass­balanced trim tabs set near the inboard end. These tabs were apparently designed as interchangeable servo units, for a small arm at the outboard end extends up from the right one and down from the left, and captured enemy documents show an anchoring arm designed into the stabilizer trailing edge. However, the operational experience or Allied bombing made completion of this plan impossible, for the tab arms were not connected to the stabilizer and, in fact, the tabs had been riveted into immobility by small gusset plates at each end. Nevertheless, each tab had four hinges, with ball bearing units at each end and pins through yokes for Looking up and forward into right wheel well at fitting for landing gear retracting cylinder, which is attached to root rib. At upper left, attached to main spar top boom., is aileron the two in the middle. As is the case bell crank showing difference in size in push-pull rod from control stick (top) and those with the rudder trim tab, the trailing extending to ailerons (bottom). Above retracting cylinder fitting can be seen self-locking edges of the tabs are nicely flush nuts attaching fuselage skin to flange on upper wing surface. riveted. One­piece pressed­aluminum which, though approximately like dihedral, too. stabilizer fillets are held in place by our laminar flow foils, has a plan The wing is built around a a leading edge pin which moves up form which is angular, to say the composite I­beam main spar having and down between greased strips least. The leading edge has a 20­ steel booms and built up dural web, riveted to metal brackets just above deg. sweepback; the spar sweeps tapering in depth from 14½ in. at the the adjusting jack, and by screws – back 12 deg., starting at the centerline to 3 in. at the tip one top and bottom – 10 in. aft of fuselage side; the trailing edge attachment fitting. Spar boom caps the stabilizer spar. sweeps forward 8½ deg. to the are ¾ in. thick at the centerline, the There are many interesting outboard side of the power plant; upper being 4¼ in. wide, the lower variations in both design and then sweeps back 5 deg. from there 4¾. workmanship in the 262's wing on out. All this and 6 deg. Built in two sections, the spar is

Looking up and aft into main gear well. Seen are centerline fairing bottom part of cylindrically shaped cockpit liner, a unit designed doors, which serve as landing gear uplock, and construction of for pressurization but unused in this way. Opening in front of main auxiliary spar will be noted. Just above this spar can be seen spar takes 53-gal. reserve fuel tank.

JL McClellan: Me-262 Copyright 2005 p 15 of 40 Top photo, made from left main wheel well, shows fairing door operating cylinder fitting on aft face of main spar at left center, with universal joint connection to box-type bell crank which is, in turn, universally-connected to fairing doors, corner of which is shown at lower right. Flat tie rod on upper corner of bell creank is connected to crank, which distributes power to aft end of doord, details of which are shown in center photo. Con- necting linkage here is bolted to box-type structure attached to front face of auxiliary spar. Lower photo is of German pespective sketch, showing how unit was designed.

JL McClellan: Me-262 Copyright 2005 p 16 of 40 open automatically at 186 mph. in gliding angle and at 279 mph. in a climb. The 5¼­in. wingtip, with its integral formation set in a transparent plastic covering, is built in two halves, flush riveted to an inboard rib and spar. The two halves, flush riveted to an inboard rib and spar. The two halves are welded together around the outer edge and, on at least one craft, a thoroughly sloppy weld it was. Its method of attachment, however, is neat and can be accomplished fairly fast with simple tools. A horizontal pin near the leading edge slips into a holed angle plate on the wingtip rib, then the tip is pushed toward the planes so that an angle bracket slips int a forged fitting riveted to the end of the spar, whereupon a through bolt with self locking nut is pushed down from the top through small access holes. At the time the tip is pushed toward the wing, a vertical plate slips into a yoke attached to the end of the auxiliary spar with the result that a Phantom view showing installation of nose landing wheel, which is depicted in exploded three­way fastening is obtained with view. Inset is cutaway of nose wheel strut. Not that original plans called for conven- only one bolt being necessary. tional torque scissors, however, late model 262's had built-in shimmy dampers. All metal ailerons are of conventional design, having a trim tabs, those on aileron tabs are channel­section aluminum spar, simply straps bolted to the aileron rolled sheet aluminum leading edge, and hooked around pins in the tab. and stamped flanged ribs. At the Like those on the other tabs, trailing edge the two skins surfaces however, the trailing edges are are crimped and riveted to a flat 3/3­ neatly flush­riveted. in. strip. Here, as on the rudder and Flaps are built in two sections: stabilizer, the rivets are not flush. The inboard (which has a 21¾­in. The ailerons are built in two chord) extending 38½ in. from the sections. Each have a 42­in. span, wing root to the power plant, and and the two sections are connected the outer section extending 48¾ in. via the control bracket, which is split from the power plant. With rolled so that one half is riveted to the aluminum leading edges, stamped outboard rib of the inner section, the channel­section spar, and other to the inboard end of the outer conventional ribs, they are built in section. A self­aligning ball baring two halves, bolted together except hinge also serves as a connecting at the trailing edge where the skin point for the two sections, and surfaces are crimped and riveted similar bearings re bolted to ribs aft (with brazier head rivets) to a ½­in. of the auxiliary spar at each end. aluminum strip. Evidently the 38­5/8 x 3 in. trim Ball bearing rollers at both ends tabs were originally proposed as of each section run in 7­in. steel servo tabs, but in practice they guides which re bolted to the ended up only as ground­adjustable auxiliary spar so that, in operation, units, for the control arm, riveted to the flaps move back and down, for the outboard end of the inner aileron the guides slant down 35½ deg. section, is attached by a turnbuckle from the top to the bottom wing rod to the aileron­operating bracket surface. This action is imparted by rather than being attached to the hydraulically operated toggles Looking aft and up into nose wheel well at wing to give the servo action. which force the flap bodily aft retracting cylinder attachment. As nose Unlike the elevator hinge points approximately 5½ in. – and down wheel retracts, it strikes tubular linkage to provided in the rudder and elevator because of the guide – except for pull and lock fairing door closed.

JL McClellan: Me-262 Copyright 2005 p 17 of 40 Phantom schematic view of hydraulic system.

the final 5 deg. of flap action, which is a pivot movement. The upper wing surface extends out over the flap so that even when extended to the full 50 deg., the flap leading edge is shrouded for 1½ in. The flap actuating cylinder is set at a 45­deg. angle to the front face of the main spar directly ahead of the oleo hinge point and is attached to one corner of a triangle whose apex is its hinge point on the spar. Where the piston attaches there is also attached a push­pull rod which extends across the plane to the left to a bell crank set just over the left power plant, with a push­pull rod going straight back to the aft face of the auxiliary spar. Here it is connected to an arm extending down from a torque tube connected to the toggles which force the flaps back and down. Quickly removable cover for hydraulic reservoir filler, a unit very similar to many used on Focke-Wulf 190. Four of five of these units on Me-262 are interchangeable, but the fit in some cases was so bad that doped fabric strips had to be added as is evident here.

JL McClellan: Me-262 Copyright 2005 p 18 of 40 Phantom view of Me-262 surface control system. Note adjustable mas balsnce in linkage of both elevators and rudder. These are in addition to balances built into control surfaces themselves.

Right side flaps are actuated by a examined has markings at 0, 10, requiring maintenance give rise to tube going straight back from the 20, 30, 40, and 50 deg., with the the belief that it may have been base of the triangular member 20­deg. mark in red for takeoff. employed to facilitate production by connected to the actuating piston. Three of the lower wing skin eliminating blind riveting. Pilot error in forgetting to lower panels, extending over three ribs Quite an unorthodox method is the landing gear is avoided through each, are held in place by flush used to attach the wing to the the system being so arranged that the screws placed approximately 1½ fuselage. Near the base of the root flaps cannot be extended until the in. apart. While the primary nose rib, 9 in. aft of the leading landing gear has been put down. purpose may have been to facilitate edge, a 1­in. bolt goes through a The left outboard flap on the craft access, the small number of units two­sided forged bathtub fitting

Bottom of control stick, seen extgending through ball and socket Elevator bell crank and trim tab (unused because trim tabs were joint in bottom of cockpit liner, with aileron torque tubes extending riveted to elevators) over auxiliary spar attached to bottom of to right and elevator tube extending aft. cylindrical cockpit liner.

JL McClellan: Me-262 Copyright 2005 p 19 of 40 Top of one of two 238-gal. main cells show- ing installation of two booster pumps, ply- wood covering, and supporting straps.

Schematic diagram of Me-262 fuel system showing: (1) and (2), left and right engines; (3) fore fuel tank; (4) auxiliary fuel tank; (5) aft fuel tank; (6) extra auxiliary tank; (7) and (8), valves for left and right power plants; (9) and (10) left and right engine safety petcocks; (11) reverse vavle; (12) fuel pumps. Craft studied lacked extra auxiliary tank (6), and reports from abroad indicate Germans were unable to get this modification into more than few planes before their defeat.

Inside rear fuel cell showing pressed fitings between stringers to which fuel cell is bolted for suspension. Front bulkhead in this section is aluminum alloy supporting rear armor plating, and aft web is sheet steel. Plywood buffer sheet at bottom is screwed in place.

JL McClellan: Me-262 Copyright 2005 p 20 of 40 Phantom view showing final modification — the Me-262-B2 — a meant moving fuel tanks, radio and other equipment farther aft in two-man radar-equipped night fighter. Addition of extra seat rear fuselage section. aft side designed for a 20­in. piston similar tie rods on the trailing edge boom of the spar, is a bell crank travel. In preparing the craft for of the fairing doors. from which 1­in. push­pull tubes flight tests it was found that the main Thus, when the oleo strut hits the extend, with one universal joint in wheels had considerable lateral play, actuating valve, the piston moves each at the fuselage side (to but when the normal 1.200 lb. to the right, forcing the tie rod­ compensate for spar sweepback) out pressure was built up, the wobble connected bell cranks to snap the to bell cranks set just ahead of the disappeared. doors closed under the wheels, with aileron control arms.. The retracting jack is bolt­hinged the 90­deg. change in direction Attached to the aft face of the to a steel fitting bolted to the root rib between the units serving as the angle bracket on the stick is a 5/8­in. at the end of the front spar of the locking mechanism after the elevator operating tube going aft to a landing gear torque box, while the hydraulic pressure on the piston is self aligning ball bearing crank set piston is attached to the front of the relieved. just over and ahead of the auxiliary oleo strut by a ball and socket joint. The nose wheel retracts aft and spar, from which a 1­in. tube Fairing for the main gear is built up into a well below the armament extends to the left side of the in two section, both of which are compartment, the wheel, near the fuselage and another bell crank to double­skinned grid­type structures end of the retracting arc, striking a connect to a similar sized push­pull with the top section hinged to the transverse tube which pulls the tube going aft. A third bell crank is torque box end and the lower bolted double skin fairing door closed. set in the empennage near the to a bracket welded to the oleo Spring loaded pins moving into the stabilizer leading edge. Extending piston just above the axle. piston serve as up and down locks. straight aft from this crank is another In operation the main wheels German drawings studied in push­pull rod connected to the swing up and into the bottom of the connection with this article show elevator horn and, just ahead of the fuselage, with the right strut provision for the conventional horn, a large mass balance which operating an actuating valve at the torque scissors, but on the later can be ground adjust on the fulcrum. end of its arc. This valve in turn model craft examined, the nose This balance is in addition to closes fairing doors which are wheel contained a built in shimmy those already noted as being set in hinged at the fuselage centerline and damper. The nose gear retracts and the elevators themselves, and may which serve as the landing gear up extends after the main wheels have be a late modification. Reports from lock. been locked either up or down. abroad have indicated that at speeds To accomplish this, a hydraulic Both the landing gear and flap over 500 mph. the ailerons and cylinder is attached parallel to the aft operating systems have connections elevators of the 262 become face of the main spar just to the left with a compressed air bottle which extremely hard to move and that an of the fuselage centerline. Its piston can be cut in for emergency extendable control stick designed to is connected to a welded steel box operation of the two systems. give increased leverage had been type bell crank which, in turn, is Surface controls present several developed. However, no such stick, attached by a universal joint to odd and interesting features. The or provisions for its installation another box bell crank set between control stick, for example, is could be found on the craft studied, two stamped flanged vertical plates mounted in a ball and socket joint and it is held possible the mass set along the centerline. At the set in the bottom of the cockpit balance just discussed has been lower corner of this bell crank are liner, extending down 4 in. and utilized in its stead. universal joint tie rods connected to ending in a welded angle bracket. Rudder pedals are very similar to the leading edge of the built­up Attached by a ball bearing joint to those on the FW­190, incorporating fairing doors, and at the upper rear one face of this bracket is a 3/4­in. the main wheel brake pedals as corner is a flat steel tie rod tube extending to the right above integral units. A torque tube extends connected to a triangular shaped the main spar. Just inside the aft from the right pedal inside the built­up bell crank attached to fuselage, and bolted to the top cockpit liner, then through a seal to a

JL McClellan: Me-262 Copyright 2005 p 21 of 40 bell crank where another tube whether the Luftwaffe went ahead Span ...... 40 ft. 11½ in. extends to the left side of the in the face of his orders is not Length...... 34 ft. 9 in. fuselage to a second crank which is known, but one final modification Height (fin above ground)...... 21 ft. 4 in. connected with the push­pull tube of the craft ­­ the Me­262 B2 – was Wing area (approx)...... 270 sq. ft. extending to the empennage, where in the works when the Germans Chord (root)...... 8 ft. 4 in. a third crank, with adjustable mass capitulated. Chord (tip)...... 2 ft. 9¾ in. weight, is connected to double tubes This was to make the plane a Aspect ratio...... 7.5 connected to the enclosed rudder two­man, radar­equipped night Wing loading ...... 44.5 lb. horn. fighter. Principal changes Wt. empty ...... 8,514 lb. The fuel system consists of two necessary were made in the Useful load ...... 7,106 lb. 238­gal. main tanks plus a 53­gal. cockpit, where the pilot's seat Gross wt...... 15,620 lb. reserve and, at least in design plans, appears to have been pushed High speed (red line) ...... 658 mph. and auxiliary tank of about 170 gal. forward slightly to help make room Range ...... 50-90 min. capacity. Both self­sealing main for addition of the radar operator's Max. thickness, 35% of chord. tanks have plywood coverings and screens and seat immediately Max permissible CG., 30% MAC are suspended by two straps on the behind. This, of course, meant ends of which are bolts that go up changing the design of the canopy through pressed fittings riveted to to give the necessary length, and the inside of the fuselage skin about relocation of the aft fuel tank, two­thirds of the way up the side. normal radio equipment, oxygen Nuts are put on the bolts through bottles and master compass, all of access holes in the fuselage skin, which were pushed further aft in with the holes covered by doped the fuselage. fabric patches. Study of the plans for this Each of the main fuel cells has change does not indicate that much, two booster pumps and the reserve if anything, had been done to tank has one, the system being so compensate for the added weight arranged that fuel can be pumped aft of CG and, since the craft had to from any tank to either engine, or be trimmed nose heavy for take­off fuel from the rear tank can be as originally designed, it is pumped to the front. believed that even more trim had to The reserve tank (at least some of be applied for the night fighter these have not been self sealing) version. Too, since the 262 was goes just in front of the main spar. It not the most maneuverable to begin is trapped to a single­skin panel, 19­ with, it is believed that the radar­ 3/4 in. deep by 66¼ in. wide, that is loaded version was not as good a reinforced by six hat shaped combat craft as the original day stiffeners and is attached to the fighter version. fuselage by flat screws placed approximately 1¾ in. apart. The concluding part of this study Evidence of the Nazi's attempts to will cover the Junkers Jumo 004 get more range out of the Me­262 is gas­turbine jet­propulsion power shown by plans for installation of plants, used in the Me­262 but the 170­gal. auxiliary tank aft of the designed for use in other craft as rear main cell. It is not known how well. extensively, if at all, this plan was carried out, for the craft studied was ACKNOWLEDGEMENT the latest model produced and it had no such installation. Instead, the For unusual cooperation, AVIATION is deeply grateful to Col. J.M. Hayward, radio was installed in the space and, Chief,Technical Data Laboratory, a little farther aft, the master ATSC, and to Capt. Irving P. Brown, compass and oxygen bottle. Access Chief, Capts. W.H. Carter and H.R. to these units is via a 17½ x 15¼­in. White and Lts. J.E. Arnoult, F.D. Van door held in place by four quick Wart, and Bernard Ellis of the Foreign fasteners. Equipment Branch. Radio installation consists of the Special thanks are due Sgt. Robert usual German equipment – FuG 16Z Foster, Hangar Chief; Staff Sgt. Harry or FuG 16ZY (VHF R/T, D/F and Kilpatrick, Crew Chief; Tech. Sgt. retransmission facilities for ground Warren Stoddard; and Sgts. George control stations) and in some cases Ledbetter and Wilfred Vigor. IFF had been installed. Whether Hitler was finally convinced that the Me­262 was not the world's hottest bomber or

JL McClellan: Me-262 Copyright 2005 p 22 of 40 DESIGN ANALYSIS OF

Messerschmitt Me-262 Jet Fighter

Part II — The Power Plant

By JOHN FOSTER, JR., Managing Editor, “Aviation” S IS THE CASE with the airframe of the Me­262, the First complete engineering study ever published on jet power AJunkers Jumo 004 axial flow plant reveals, in addition to fundamental principles of jet gas turbine jet power plant is a propulsion, the design and production compromises made compromise between design desire and available materials and necessary by limitations of materials. production facilities. Outstanding evidence of new alloy of excellent heat­ which is divided into two sections, compromises resulting from lack of resistant qualities had made it the upper being of ¾­gal. capacity materials is the fact that more than possible to get up to 150 hr. service feeding fuel to the starting engine, 7% of the air taken in is bled off for in actual flight tests, and up to 500 the lower of 3¼­gal. capacity, cooling purposes. Despite this, hr. on the test stand. feeding starting fuel to the however, most engines were found A large unit, the 004 is 152 in. combustion chambers. to have a service life of about only long from the intake to the tip of The nose cowling attaches by 10 hr., against a “design life” of 25 – the exhaust; 30 in. in dia. at the eight screws in captured nuts to the 35 hr. Additional compromises are skin around the six combustion annular­shaped combination oil tank evident in the design, which shows chambers, with maximum diameter and cooler. Having 3­gal. capacity, that the production engineer – of the cowling reaching 34 in. this tank has a baffle close to the undoubtedly hampered by lack of The circular nose cowling is inner surface so that as warm oil is both plant facilities and adequate double skinned, the two surfaces fed in from the top it is cooled as it skilled labor – has been as important being welded together near the flows around to the bottom of a factor in its construction as was the leading edge and held in position annulus and the tank proper. designer. by riveted channel shaped brackets. The oil tank, in turn, is attached But the Germans had made real Diameter at the intake end is 20 in., by 23 bolts on a flange to the progress in overcoming materials the outer skin increasing to 31½ in., aluminum alloy intake casting. This difficulties, for just after they the inner to 21½. Inside the unit comprises the outer ring, with capitulated that development of a cowling is an annular gasoline tank flanges on both front and rear faces,

Front of Junkers Jumo 004 intake casting (left), with oil lines at extend through vertical streamlined fairings. Right: Aft face of bottom. Holes in outer flange are for attaching oil and starting-fuel intake casting, with front compressor bearing held in place by tank assembly. Twelve studs on inner ring hold bevel gear round plate attached to ten studs. Bolt holes in outer flange are for assembly, from which drives for accessories and oil pumps attachment to compressor stator casting.

JL McClellan: Me-262 Copyright 2005 p 23 of 40 Eighth compressor disk and rotor showing: Small retaining screws set in roots of blades; serrated ring around which is bled par of cooling ari; and slot-and-lug arrangement for transmitting torque from drive shaft to disk faces. Entire compressor assembly is held together by tie rod, end of which protrudes from shaft end.

ten springs held in place by a plate bolting to the intake casting. The outer bearing races are mounted in separate sleeves which fit on the compressor shaft. This design not only allows for preloading the bearings during assembly to ensure even distribution of thrust, but the bearing assembly can be left intact during disassembly simply by withdrawing the compressor shaft from the inner sleeve. Next in the fore­to­aft sequence ins the aluminum alloy stator casting, which is built in top and bottom halves held together longitudinally by eleven 3/8­in. bolts through flanges on each side, with attachment to the intake casting by 24 3/8­in. bolts through a heavy flange. Running the entire length of the bottom half of the casting are three .7­in dia. passages, one serving as part of the oil line leading to the rear compressor and turbine bearings, one connecting oil sumps (which are located in both intake and main castings), and one serving as part of the oil return line from a four hollow streamlined spokes, and with the drive shafts fitting into scavenge pump set in the rear the inner ring. internally splined stub shafts on the turbine bearing housing. Moving back to the front of the bevels. There are two drive shafts Just aft of the fourth compression unit, though, we find inside the nose extending through two of the stage in both halves of the stator cowling a fairing which looks just hollow fairings of the intake casting is a slot, inside of which is a like a propeller spinner, increasing casting, one going up to the ring with a wedge­shaped leading in size to 12 in. at the intake casting, accessory case which is mounted edge pointing upstream and set to leaving approximately 220 sq. in. atop the intake casting, the other leave a .08­in. opening to bleed off intake area. This spinner houses the extending down to the main oil air for part of the cooling system starting engine, a two­cylinder two­ pumps, which are set inside the (which will be discussed later in a cycle horizontally opposed gasoline lower part of the intake casting. separate section.) engine which develops 10 hp. at The bevel gear casting, also of Like the stator casting, the stator 6,000 rpm. The starting engine has aluminum alloy, is bolted to twelve rings, which consist of inner and its own electric starting motor; and, studs set in a flange in the front outer shroud rings and stator blades, for emergency, extending out to the face of the intake casting. are built as subassemblies, then front of the spinner is a cable starter The rear side of the intake bolted in place and locked by small similar to those found on outboard casting's inner ring is cup­shaped, tabs. boat engines. The engine is 12½ in. housing the front compressor Considerable variation, both in long, 10 in. wide, 8¼ in. high, and bearing. This unit is comprised of materials used and methods of weighs 36 lb. three thrust races – each with 15 construction, was found in this The starter engine is bolted to six bearings – mounted in steel liners section. In early production units, studs in the bevel gear casting, set in a light hemispheric­shaped for example, the inlet guide vanes which contains bears to drive the housing which is kept in contact and first two rows of stator blades accessories. Each of these gears is with the female portion of the were of stamped aluminum with carried by ball and roller bearings, intake housing by the pressure of airfoil profiles; and in assembly,

JL McClellan: Me-262 Copyright 2005 p 24 of 40 ends of the blades had been pushed through slots in the shroud rings and brazed in place. In other early engines, the third stator row varied both in material and method of attachment. In some cases it would be of aluminum, but without airfoil; in others it would be of steel with the ends turned to form flanges which were spot welded to the shroud rings. The remainder were stamped sheet steel, zinc coated. One late­production engine examined showed a combination of all the variations, with the inlet guide vanes and first two rows of stator blades of stamped aluminum, and the rest steel, indicating the Germans may have been swinging over from aluminum to steel exclusively. Apparently all the steel blades had been enameled, but this protective coating on the last row, where temperatures reached approximately 380 deg. C., appeared to have been burned off. Methods of attaching blades to shroud rings also varied. On the inlet guide vanes and first two rows, the ends of the blades had been pushed through slots in the shroud rings and brazed in place; the 3rd, 6th, and 7th rows had a weld all around the blade end; the 4th, 5th, and 8th row blade ends had been formed into split clips which were spotwelded to the shroud rings. The outer shroud rings are channel shaped with an angle bracket riveted to each end, this bracket in turn being bolted to a stud set in the casing just inside the mating flange. Inner shroud rings are flanged along the leading edge, with the exception of the 7th row, which is channel shaped. Except for the inlet guide vanes and the last row of stator blades, which act as straighteners, stator blades are arranged as impulse blading – they are set at nearly zero stagger and simply serve as guides to direct the airflow into the rotor blades. Top and bottom halves of stator casting. These sections are bolted together longitudinally, with flange on front end bolting to intake casting, that on aft end to main casting. Light colored blades are aluminum, darkere are enameled mild steel. Germans were evidently changing over from aluminum to steel blades throughout stator at war's end. Sketches at top show method of attaching stator blades.

JL McClellan: Me-262 Copyright 2005 p 25 of 40 Rear view of main casting showing rectangular cooling air passages and the six combustion chamber inlets. Five larger cored passages in base of ribs are cooling air passages, smaller is oil line. Aft turbine bearing fits in rear end of this casting.

Three-quarter front view of main casting which supports entire engine. At top is engine attachment fixed to one of six possible pickup points spaced around unit. Rectangular openings infront outer rim are cooling air passages, and air inlets from compressor to combustion chambers are between faired struts between chambers and serrated ring. Air passing betrween th serrations and those on last compressor disk is also used for cooling. Studs around center core are for attaching aft compressor bearing housing. The compressor rotor is made up of eight aluminum disks held together by twelve bolts each through shoulders approximately at mid­diameter, with the entire unit being pulled together by a 38.75­in. long, .705­in. dia. tie rod which has been estimated to have a stress of some 40,000 psi., with a force to pull the assembly together figured at about 16,000 psi. Diameters of the disks increase from the low to high pressure ends as follows: Stage 1, 13.86 in., Stage 2, 14.68 in., Stage 3, 15.61 in., Stage 4, 16.44 in., Stage 5, 17.18 in., Stage 6, 17.85 in., Stage 7, 18.24 in., and Stage 8, 18.34 in. To carry the compressor bearings there is attached to each end disk a steel shaft with an integral disk carrying a round­faced washer. This shaft goes through the disk and is

Closeup of front of main casting showing rear compressor bearing and housing in place. Large screws seal off passages left by cores used in making casting.

JL McClellan: Me-262 Copyright 2005 p 26 of 40 tightened by a nut so that the face of this washer (rounded to facilitate alignment) bears against the disk face. The flange on the rear shaft has six slots around its outer edge, into which fit projections on the rear disk. Thus torque is transmitted from the turbine to the rear compressor disk, and from there on to the other disks by the bolts previously noted as fastening the disks together, the torque being transmitted to the compressor unit around the faces, rather than through a central shaft. Compressor rotor blades, of which there are 27 in the first two stages, 38 in the rest, are all stamped aluminum with machined roots fitting into pyramid shaped slots in the rotor disk. Through the aft face of each blade root, directly under the blade trailing edge, is a small screw set longitudinally and extending into the disk. Tip stagger of the blades is about the same through the first six stages of compression, but increases in the last two. Chord of the blades decreases through the eight stages as follows: 1.95 in., 1,94; 1.34; 1.33; 1.30; 1.30; 1.24; and 1.21. Blade profiles in the first two Head-on view of combustion chamber casing with combustion chambers and stages are very similar (possibly ignition interconnectors and plugs in place. Every other chamber has ignition pluig. even designed to the same section), while the third stage has a thicker Moreover, in the base of each of compressor and combustion section. Stages 4, 5, and 6 have the six ribs supporting the chambers, the main casting changes thinner sections (here, too, possibly combustion chambers, there are the shape from annular to circular at the same), with about the same cored passages, five of which carry the entrance to the chambers. chord as Stage 3, while the last two cooling air, one carrying lube oil. In the front of the casting, at the stages, though set at greater pitch And, while the air passage area tip of the last stator row, is an 18­ and having slightly narrower chord, remains constant between the 3/8­in. die. ring with a serrated inner have generally similar camber and profiles. Clearances between the rotor blades and the stator casting are .103 in. over the first three stages and .04 over the remaining five. Axial clearances between rotor disks and inner stator shroud rings range from .1 to .15 in., and axial clearances at roots between rotor and stator blades are .5 and .6 in. Backbone of the 004 is a complex aluminum casting which, in addition to providing the three engine attaching points, supports the compressor casing – through 25 bolts – the entire combustion chamber assembly, the turbine nozzle, the aft compressor bearing, Exploded view of combustion chamber showing main components. At left is outer casing, mad of mile steel; center is flame tube, showing swirler at front, fuel nozzle, the two turbine bearings and, ignition plug connection (on side) and stub pipe assembly; and at right is aluminized through the combustion chamber steel liner with corrugations to carry cooling air along inside of casing. casing, the entire exhaust system.

JL McClellan: Me-262 Copyright 2005 p 27 of 40 Turbine nozzle inlet ducting which changes air passage from indvidual combustion chamber circles to annular shape before entering nozzle.

Mild steel double-skinned casing which surrounds combustion chamber ignition plugs and interconnectors. Heavy transverse ring chambers. Note holes in front ring which carry cooling air into around outside of casing carries tier rod braces into main casting ducts between the two skins. Access holes lead to combustion and also serves as attachment for aft engine pickup point.

JL McClellan: Me-262 Copyright 2005 p 28 of 40 which the combustion chamber casing bolts, are twelve raised longitudinal ridges arranged in pairs. These have machined faces having four bolt holes and two aligning pins serving s the forward engine pickup points. With six such pickup points, the engine was designed for a wide variety of mountings. In the case of the Me­262 plates with collared nuts were fastened to the two on either side of the topmost unit. Overall length of the main casting is 37¼ in., with the previously mentioned ribs tapering down from the aft face of the ring structure to the central longitudinal member which has an 8¾­in. dia. ant the aft end. The aft compressor bearing, having 16 rollers, is set in the front of the main casting inside the serrated ring, the housing being attached to the casting by 14 bolts. The turbine thrust bearing is set inside the main casting, with the centerline of the balls 24­3/8 in. back of the front edge of the serrated ring, and the main turbine roller bearing is bolted into the rear end. Each of the six combustion chambers is built up of three major components having a combined Front view of turbine nozzle assembly showing rear turbine bearing and diaphragm weight of 19 lb. First, there is a plates in place. Cooling air enters two holes seen just below bearing, goes up between mild steel outer casing, of 5¾ in. diaphragm plates and through nozzle roots, then out through openings in trailing edges. dia. at the entering end flaring out to Note36 bolt holes (in aouter rear flange) for attaching assembly to combustion chamber 8­5/8 in., and having a length of 20­ casing, also 36 series-of-three holes for carrying exhaust system cooling air. 5/8 in. The front end has a collar with a rubber sealing ring which is Third major component of the casing flange. Besides the bolt holes pushed up against the aft face of the combustion chamber is an 11­in. in the front flange, there are 24 of main casting to take care of air long 20­gage aluminized steel liner similar size, twelve leading to six leakage and to compensate for the having a corrugated outer skin ducts of 22­gage steel which carry difference in casting and combustion which permits cooling air to flow the air bled from the fourth chamber expansion. inside the outer casing. This liner compressor stage through the Fitting inside the front end of this fits into the aft end of the casing. combustion chamber casing, and casing is the flame tube, which has The aft ends of the combustion twelve directing air around the two main components – the entry chambers are bolted around flanges combustion chambers. These ducts section and stub pipe assembly. The to a ring of six rings which fits over also help stiffen the skin, as it takes fore part of the entry section flares there rear end of the main casting. the weight of the entire exhaust out somewhat as does the outer Ignition interconnectors between system. casing, and at the front end has a chambers are of but 15/32 in. dia., Six large hand holes are cut in the six­blade swirler. This unit is made and starting plugs are provided in casing just behind the flange. These of 22 gage mild steel with a black three of the six chambers. These give access for making minor enamel coating. The stub pipe elements, as are the fuel plugs, are adjustments to burners and the three assembly is made up of ten flame enclosed in streamlined fairings. ignition plugs. chutes welded to a ring (which is Surrounding the combustion A little more than halfway aft welded by brackets to the rear end of chambers is a 16­gage mild steel around the combustion chamber the flame tubes and to a 4­in. dished double skinned casing having casing is a heavy collar comprised of baffle plate at the rear. To help flanges welded at both ends – that two channel shaped members, and direct air into the chutes, ½­in. at the front end attaching by studs inside the casing at this ring are six circular baffle plates are riveted to to the main casting; that at the rear tie rids, connecting it to the main the forward ring. Material of this attaching to the turbine inlet duct casting. Any one of these six units unit is mild steel with an aluminized outer flange, the nozzle ring can serve as the aft engine pickup finish. assembly flange, and the exhaust point; in the case of the Me­262 it is

JL McClellan: Me-262 Copyright 2005 p 29 of 40 Hollow blade turbine assembly. Cooling air is forced inside flange near hub and up behind sheet spotwelded to disk, then through blade roots, and out through tips. Gear teeth cut on shaft just ahead of rear bearing mounting point drive oil return pumps. Turbine shaft is attached to compressor shaft by splined coupling.

the top one. lifted off. Next the rear compressor Detail sketch of turbine disk showing Ducting from the combustion bearing assembly, torque tube, and method of attaching hollow blades. Groove in disk stub is filled with special high chambers to the turbine nozzle locking ring can be removed and temperature silver-based brazing flux, blade changes the air passage from the six the main casting assembly removed is then pinned in place, and entire unit circles to annular shape. Attached to – when the nut on the front end of heated. Two small holes on ends of disk the combustion chambers by bolts, the turbine shaft is unscrewed. The stubs direct cooling air through blade roots. this 19­gage aluminized mild steel rear diaphragm plates can then be unit is made in two parts, the rear of removed and the turbine inlet which is welded to a heavy flange. ducting and combustion chamber shaped spacers, 1 in. long and Studded to this flange from the inner assembly lifted off. Then the front tapering from 1/8 to .020 in., leaving shroud ring of the turbine nozzle diaphragm plate is removed and the a .020­in. gap down the trailing edge assembly are two mild steel turbine inlet ducting, with the through which the cooling air diaphragm plates. These, in turn, combustion chamber assembly, escapes. are studded to the rear end of the lifted out of the casing. At this In assembly, the blade tips are main casting, and so support the point, as one sweating engineer closed, pushed through slots welded inlet ducting and turbine nozzle ring. who did the job declared, “Now, to the outer shroud ring, and the On the rear of the outer turbine inlet Bub, y'can take out the individual roots are pushed through slots in the ducting a light flange mates with a combustion chambers.” inner shroud ring and spotwelded in flange on the rear of the combustion An unusual feature of the 004's place on the inner surface of the chamber casing. Thus the turbine design is the use of hollow turbine ring. inlet ducting, to which the nozzle blades through which To this ring, in turn, is welded a combustion chambers are attached, cooling air is fed from the heavy, mild steel flange and second is supported partly the diaphragms, compressor via the main casting flanged ring, the two flanges picking and partly by the skin. and supporting diaphragm plates. up with the diaphragm plates which Maintenance crews really take a The two­part outer nozzle shroud support the assembly from the rear beating as the result of the final ring is made of mild steel and both of the main casting. design, for it is a major operation to parts are welded to a ring that is Two types of 61­blade turbines get at the combustion chambers. joggled and flanged to mate with are used. Originally both blades and First, the variable­area nozzle flanges through 36 bolts on the disks were solid, later hollow blades operating shaft must be removed so inlet ducting and the aft flange of and lighter disks were introduced at that the complete exhaust system the combustion chamber casing. In a saving of approximately 40 lb. assembly can be taken off. Then, addition to the bolt holes the flange The solid disks were of hardened unless special equipment is has 36 sets of three holes for chrome steel, taking stresses of available, the engine must be placed cooling air passage. about 15 tons at maximum rpm. upright on the turbine disk and The 35 nozzles are made of Cooling is effected by spilling air burner pipes and ignition leads austenitic sheet steel, .045 in. thick, bled back through the main casting disconnected from the combustion bent to shape around a 1/16­in. against the disk face then up over chambers. Then the compressor radius to form the leading edge. the blade roots and out between the casing­main casting joint can be Between the sheets at the trailing blades. broken and the whole front end edge are spotwelded four wedge The 12¼­oz. solid blades are

JL McClellan: Me-262 Copyright 2005 p 30 of 40 forged from an austenitic steel grooves, the entire unit is put in an its maximum travel of containing 30% nickel, 14% chrome, oven at 6­800 deg. C., warmed for approximately 7­3/8 in. varies the 1.75% titanium, and .12% carbon, 20 min., then heated to about 1,050 exit area between 20 and 25%. It is corresponding closely to “Tinidur,” deg. C. in 40 min., then cooled in set in retracted position for starting a Krupp alloy known before the war, still air at room temperature before to give greater area and help prevent and are attached by three machined hardening in a gas or air oven. over­heating, then moved aft to lugs drilled to take two 11­mm. Later production units have two decrease the area and give greater rivets each. Maximum centrifugal rivets in the blade trailing edges velocity for takeoff and flying. The blade stresses have been estimated at near the tips, a modification made movement is accomplished by a 18,000 psi., and gas bending stresses necessary by cracking caused by gear­type servo motor set near the at 2­4,000 psi. Study of the solid vibration. accessory housing and connected by blades indicates that the roots didn't The turbine is attached by six a long torque tube to gears set on the get much above 450 deg. C., due to studs to a short shaft carried no two exhaust housing over one of the the cooling air flow up from the bearings housed in the main struts leading into the previously­ disk, but near the center it appears casting. The front bearing is a mentioned rack gear. the temperatures got up to about 750 single­race ball thrust, the rear a Originally the unit was supposed deg. C. This applies to service single­race roller type, and both are to operate automatically over small models, not those previously cooled by oil only Connection of ranges at extremely high speed and mentioned as having given the the turbine and compressor is vi a altitudes to give maximum longer flight and test­stand life. heavy, internally splined coupling. efficiency, but on some engines Disks for hollow blade turbines The exhaust cone is made up of examined the necessary lines had are of lighter material than the solid aluminized mild steel, and consists been blanked off. The two­position types and have attached, across the of two major components: outer operation is obtained through a front face, a thin sheet flared out fairing is double skinned, with mechanical linkage with the throttle near the center. This picks up the cooling air bled from the so that the bullet moves aft at cooling air and, via ridges on the compressor flowing between the between 7,000 and 7,500 rpm. disk, whirls it out toward the blade skins to within 15­3/4 in. of the exit Since the necessary cooling roots where it goes through two where the inner skin ends. Outside system played a very important part small holes drilled in the disk rim up the other skin from there to the end in both the design and construction through the blade and out the tip. is another skin, flared at the leading of the 004, it is felt best to note it Made of the same material as the edge to scoop in cooling air. It is briefly as a separate part of the solid blades, the hollow type are attached by spot welded study. It consists of three major formed by deep drawing a disc corrugations. stages, as follows: through a total of 15 operations. In Attached to the outer fairing by 1. Air bled off after the 4th assembling the turbine, the blade six faired struts is the inner fairing, compression stage. roots are fitted over grooved stubs tapering from 19½ in. at the turbine 2. Air taken off just after the on the disk rim. Two small holes on end to 9¾. This unit houses a rack last compression stage. each side take locating pins to hold gear – driven by a shaft entering 3. Air bled off between the the blades in place during assembly, through one of the struts – which compressor and combustion but they take no stresses. moves a “bullet” extending from its chambers. With a silver­base flux in the aft end. Actuating this bullet over In Stage 1 the air is picked up by

Top view of “bullet” which moves fore and aft in exhaust pipe to give variable area exit. Rack gear and gear box for servo-motor drive are at left.

JL McClellan: Me-262 Copyright 2005 p 31 of 40 Schematic diagram of cooling system, which takes well over 7% blades, through the blades themselves. Stage 2 air, taken off of total air intake. Stage 1 air, bled off after fourth compression between compressor and combustion chambers, is carried stage, cools exhaust system. Stage 2 cooling air taken through through main casting to cool turbine nozzles. Not course of serrations on last compressor disk, is directed through main cooling air in and out of “bullet.” casting to cool turbine disk and, on units with hollow turbine the ring after the 4th compressor row goes into the ducts continues aft bullet. and is directed into six cored and, through small holes in the In Stage 2 the air goes through the passages in the stator casting, then at flanges, between the double skin of serrations between the compressor the combustion chamber casing it is the exhaust cone outer fairing. and the main casting, into two of the divided so that some of the air goes Majority of the air goes straight on six cored passages in the casting through six ducts in the combustion aft to the end of the inner skin, but back to the turbine. Here, on the chamber casing skin, some goes some is taken through the six struts original engines, it was spilled inside the casing and around the connecting the inner fairing into against the face of the turbine disk chambers themselves. That which that unit to cool the rack gear and and moved out to escape between the turbine blades. On engines with Front end of exhaust cone showing cooling air holes in outer falnge and faired struts hollow blades, however, the air is supporting inner structure which houses rack gear for moving “bullet” to give ducted across the space between the variable area exit. Note cooling air inlets at root of strut at right. two diaphragm plates supporting the turbine disc where it is picked up by ridges and forced up through the turbine blade roots out through the blade tips. Stage 3 cooling air, bled off between the compressor and combustion chambers, is ducted through three passages in the main casting to the space between the turbine nozzle­supporting diaphragms, then up through the turbine nozzle vanes and into the slip­stream through the trailing edges of the vanes. It is estimated that Stages 1 and 3 take approximately 3% each of the total air movement, and that Stage 2 probably takes at least half as much; thus better than 7% of the available flow is taken off because of a lack of higher heat­resistant alloys. Additional performance penalties are evident in the fact that ducting is necessary, complicating both the weight and production pictures. Air is not the only cooling medium, for the lubricating system too is employed. In this system, two gear pumps circulate lube oil to the front compressor bearing assembly, the accessory­drive bevel gears, and

JL McClellan: Me-262 Copyright 2005 p 32 of 40 the accessory gears. Another the governor cam so that when the supplies oil to lubricate and cool the throttle is advanced the fuel flow Junkers Jumo 004 Weight Table rear compressor and both turbine increases and response is Intake bearings, the latter two being immediate. The governor then Casting with oil pumps, filter...... 57 lb. Bevel gear assembly & drive sprayed and splashed, respectively. takes over and adjusts the engine shafts...... 18 lb. The two main pumps, mounted speed to a predetermined value set Gear box & drives...... 35 lb. Front compressor bearing beneath the engine and driven from by the position of the cam. assembly...... 25 lb. the bevel gears through a nose ...... 135 lb. casting strut, deliver 190 gal./hr. Compressor Stator csting & blades...... 200 lb. each. The two­part scavenge unit is ACKNOWLEDGEMENT Rotor with stub shaft & tie rod...... 220 lb. built into the turbine bearing • In addition to the staff of the Foreign housing and is driven by a gear cut Equipment Branch, Technical Data Center Section Main casting & fittings...... 163 lb. into the sleeve which serves to Laboratory, ATSC, AVIATION extends Utter casing & fittings...... 100 lb. return oil to the cooler. In level heartfelt thanks to Col. R,L, Wassell, Chief Rear compressor bearing Special Research Branch, Power Plant assembly...... 6½ lb. flight, one part of the unit, a 300 Front turbine bearing gal./hr. puma, returns oil through Laboratory, ATSC; Lt. Col. P.F. Nay, assembly...... 7½ lb. one of the cored passages in the Assistand Chief; Maj. R.I. Berge, Rear turbine bearing assembly & scavenger pumps...... 9 lb. main casting, then through a passage Administrative Officer; Capt. W.C. Gerler, ...... 286 lb. in the stator casting to the pump in Project Engineer; and Mr. A.T.Miller, Chief the bottom of the intake casting. In Technician. Combustion climbs, the other part, a 90 gal./hr. 6 chambers burners, igniters, gear pump, picks up the oil and & interconnectors...... 116 lb. feeds it into a common return line to General Data the air­oil separator. Oil is returned Wt. (without cowl)...... 1,669 lb. Turbine Wt. (with cowl)...... 1,775 lb. Inlet ducting & joint rings...... 42 lb. from the main pump to the separator Specific wt...... 85 lb Nozzle assembly...... 43 lb. by a 300­gal./hr. driven by the same Thrust...... 1,970 – 1980 Diaphragm plates...... 10 lb. lb. Disk & blades (solid)...... 151 lb. shaft as the delivery pumps. Pressure ratio...... 3:1 Shaft, sleeve, fittings...... 30 lb. Two types of fuel are used on the Fuel consumption...... 2,720 – 2,745 Compressor coupling...... 7 lb. 004: gasoline for starting and J­2 lb./hr. Maximum speed...... 8,700 rpm. brown coal “crud” for running. The Idling speed...... 3,080 rpm. Exhaust gasoline is carried in the lower part Idling speed fuel consumption.... 614 lb./hr. Bullet assembly...... 190 lb. Length...... 152 in. of the annular tank set in the nose Maximum dia...... 34 in...... 1,430 lb. cowling, and is automatically cut off Frontal area (cowled)...... 6.4 sq. ft. after ignition at about 3,000 rpm. Accessories Oil tank...... 27 lb. This is fed by an electrically driven Fuel pump...... 9 lb. pump delivering 80 gal./hr. at 28 psi. Governor...... 17 lb. Near the end of the war it was found Number of Blades, Compressor Tachometer...... 1½ lb. Stator Rotor Air­oil separator...... 4 lb. that centrifugal crude oil was also Inlet guide...... 32 . . . . Bullet control servo motor...... 17½ lb. used as operating fuel. 1...... 61 27 Drive shaft for bullet...... 4 lb. 2...... 61 27 Fuel filter...... 2 lb. The main single­stage electrically­ 3...... 59 38 Fuel non­return valves...... 1 lb. driven gear type pump has a 4...... 61 38 Throttle linkage...... 7 lb. maximum delivery of 500 gal./hr. at 5...... 61 38 Misc. fittings & attachments...... 25 lb. 6...... 71 38 Engine mount brackets...... 15 lb. 1,000 psi. at 3,000 rpm. 7...... 71 38 ...... 115 lb. Most interesting of the accessories 8...... 57 38 is the all­speed governor, a 17­lb. Starter Starter engine...... 36 lb. unit consisting basically of a Gasoline tanks & supports...... 20 lb. centrifugal governor, oil pump and Gasoline pump...... 6 lb. spill and throttle valves. In Igniter coils...... 3 lb. operation, oil goes through a passage Net dry weight with starter...... 1,625 lb. to the pilot piston and is distributed Accessories to outer faces of either the spill or Generator fittings...... 36 lb. Hydraulic pump...... 8 lb. follow­up piston, depending on ...... 4 lb. movement of the flyweights. Both the pistons move at the same time, Cowling adjusting the fuel spill to counteract Starter engine cowling...... 4 lb. changes in engine speed. The Starting fuel tank cowling...... 17 lb. Remainder of cowling...... 85 lb. distance between the spill and ...... 106 lb. follow­up pistons varies according Total dry weight, completely to the flow of oil through the cowled engine...... 1,175 lb. passages so that the spill piston action is a step­by­step operation controlled by the follow­up which returns to normal position after each step. A throttle valve is linked with

JL McClellan: Me-262 Copyright 2005 p 33 of 40 JL McClellan: Me-262 Copyright 2005 p 34 of 40 JL McClellan: Me-262 Copyright 2005 p 35 of 40 JL McClellan: Me-262 Copyright 2005 p 36 of 40 JL McClellan: Me-262 Copyright 2005 p 37 of 40 JL McClellan: Me-262 Copyright 2005 p 38 of 40 JL McClellan: Me-262 Copyright 2005 p 39 of 40 Edit ors note: published in Aviation during the war years, between May 1943 and November 1945. The subjects were the This article was originally published in the October Bell P­39 Airacobra, Curtis C­46 Commando, and November, 1945 issues, Volume 44, numbers 10 Fleetwing BT­12, Douglas A­20 Havoc, Bristol and 11, of Aviation magazine, published by McGraw­ Beaufighter (British), deHavilland Mosquito (British), Hill Publishing Company of New York, NY, USA. North American P­51 Mustang, Lockheed P­38 This reconstruction is derived from microfilm. The Lightning, Focke­Wulf FW­190 (captured German), source is University Microfilms International, Boeing B­17 Flying Fortress, North American B­25 Publication No. 364 (Aviation Week and Space Mitchell (specifically, the B­25H and B­25J models), Technology), Reel No. 21 (January 1945 – December Mitsubishi “Zeke 32” Hamp (captured Japanese), 1945). The source was a tightly bound volume, so that Consolidated Vultee B­24 Liberator, Fairchild C­82 there is some distortion of the images, especially near Packet, and Messerschmitt Me­262 (captured German), the binding. It has not been practical to remove or with one article dealing specifically with the Me­262's compensate for all the distortions, so none of the Jumo 004 jet engine. Some of the analyses were illustrations in this reconstruction should be considered authored by senior members of the design teams at the reliable sources as to fine details of shape, proportion or original manufacturers, while others were written by spatial relationship. The distortions are, in general, staff editors of Aviation magazine. small, and should not detract from a general The original articles were copyright to their appreciation of arrangement and relationship. respective sources — the employers of the authors, The editor has attempted to represent the original following general practice of the time. layout of the article, but there are some exceptions. This reconstruction is compilation copyright JL Limitations in the compositing tools cause a difference McClellan, 2005. in the text flow relative to the illustrations, compared to the original, so that some changes have been made, to compensate partially for that effect, and the tabular data have been removed from the flow of text and brought together on a single page after the text, partly to make them more accessible, and partly to sidestep problems with page layout. In addition, the original Part II article contained a foldout. Images from that sheet have been added at the end of the article. The images have considerable overlap, so that no information is lost, even though it is not practical to reproduce the original illustrations. This article was one in a series of design analyses

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