The Technical Journal of the Editorials International Human-Powered troversial political position. The FCC Vehicle Association Before the Take-off agreed, and the public service counter- David Gordon Wilson, Editor The lead article in the current issue (vol. 5 advertising that Banzhaf brought about 11 Bacon Street no. 3, October 1988) of HPV News, Marcia led rapidly to an astounding turnaround Winchester, MA 01890-3808, USA Lowe's " Have a Powerful in what had seemed for a century to be (617) 729-2203 (home) Future", impressed me because it describ- tobacco's impregnable dominance. (617) 253-5121 (office) ed the situation of human-powered The time is ripe for a similar transfor- IHPVA vehicles in terms that reminded me of mation in the apparently universal sanc- P.O. Box 51255 nonsmokers' rights a mere twenty years tion given to motor vehicles to clog our Indianapolis, IN 46251, USA ago. One can make a case that smokers cities, put smog into our air and to make (317) 876-9478 have rights to smoke in certain circum- our whole way of life totally different stances. But in those days, one could be from that for which we were equipped by an asthmatic in the hospital and have nature. Virtually every city in the Marti Daily President doctors and nurses smoking over one, to "western" world is facing massive prob- Adam Englund Secretary take what might now seem like an ex- lems of traffic congestion, to which there Bruce Rosenstiel Treasurer treme example but was then common- seem no easy answers. Human-powered Paul MacCready International place. Virtually one hundred percent of vehicles are not the complete solution to President the US population, a proportion that these problems, but they can play a vital Alec Brooks VP Water includes almost all smokers, would today role in a "kinder, gentler" transportation Glen Cole VP Land agree that it is wholly right that sensitive pattern. The technical advances that we Glen Ray VP Air nonsmokers should be given some pro- seek in the IHPVA are helping to prepare David Gordon Wilson Executive VP tection from secondhand smoke. Marcia ordinary citizens to accept some future Allan Abbott Board Members Lowe's fifth paragraph struck me as transformation in the present dominant Mike Burrows analogous to the smoking physician role of motor vehicles. All we need now is Marti Daily situation: "The World Bank, the main a Banzhaf to take the vital catalytic step. Peter Ernst source of urban transit investment in the Chet Kyle developing world, published a 1985 study The End of a Brave Effort Gardner Martin on the Chinese transport sector that does Matteo Martignoni not even mention the word , al- Bike Tech, "Bicycling Magazine's Dennis Taves though the overwhelming majority of newsletter for the technical enthusiast", David Gordon Wilson trips in China's cities are made by bike. will no longer be published after 1988. This is sadly typical of a policy environ- While it is easy to criticize a publishing ment in which only motor vehicles are empire for not continuing to back a taken seriously." worthy experiment, we should, rather, Human Power is published quarterly by The protection of nonsmokers pay tribute to the support that Rodale the International Human-Powered throughout the world came about Press devoted for many years to some- Vehicle Association, Inc., a non-profit through the action of one man, an MIT thing that could not promise any financial organization devoted to the study and engineer-turned-lawyer named John return. Although Human Power and Bike application of human muscular potential Banzhaf, who petitioned the Federal Tech should have been rivals, we have to propel craft through the air, in the Communication Commission that the always had friendly relations, with water and on land. Membership informa- overwhelming and unopposed advertis- someone from the IHPVA board usually tion is available by sending a self- ing by tobacco companies represented an one of the contributing editors. Bike Tech addressed, stamped business-sized unfair and unequal treatment of a con- started out at a very high level under the envelope to: editorship of Crispin Miller, now pursu- IHPVA In This Issue- ing his doctorate at MIT, and ended in the P.O. Box 51255 same high tradition with Bruce Feldman, Indianapolis, IN 46251-0255 USA Prone-PositionRecumbent Bicycles 1 who will continue with Rodale as editor Members may purchase additional by Allan V. Abbott of its publication. We salute copies of Human Power for $2.50 each. Editorials by David Gordon Wilson 2 them and their colleagues, and wish them Letters to the Editor 3 Nonmembers may purchase issues for well. Vibrational Stress on Cyclists 4 $4.00 per copy. by Rainer Pivit Material in Human Power is copyrighted Constructing a Fairing Mold Plug 7 How-To-Build Articles by the IHPVA. Unless copyrighted by the by Greg Trayling author(s), complete articles or representa- A Simple Programfor Propeller Per- 8 It is always good to appear respon- tive excerpts may be published elsewhere formance Prediction by Theodor Schmidt sive. A letter from P. Michael Ditchen in 13 if full credit to the author(s) and the Reviews the October 1988 HPV News laments not Frontal Area Versus Surface Area- 13 IHPVA is prominently given. having many "how-to" articles. I hope Prone or Supine? by Chester R. Kyle that we will have several in this or later Special thanks to the authors, Sabina Sharpy-Cycle: An Experiment in 18 Rataj, Marti Daily, and The Professional Pedal Power and Screw Propulsion issues of Human Power. Three factors Edge, without whom this issue would not by Philip Thiel combined to bring this development. It have been possible. Index of Human Power Articles 19 seemed, as it did to Michael Ditchen, to 2 Human Power 7/2 be a good idea. I had seen several excel- secretary at MIT, will usually be able to just in front of the front would be lent articles in the NWHPVA newsletter transcribe it when there are no other high- easy to construct, or it could be done with (Seattle area) and in "hpv nieuws" priority claims on her time. (Alas! Sabina thin plywood as was the "Cafe Racer" (Holland) and had written for permission is moving on, and I don't know how we (vol. 6/2), or a combination. Some to publish them in their entirety or in a will manage for the next issue without questions are these: shortened form. And, third, there has her help. I do some transcriptions myself, 1. How detrimental is an opening been a seemingly sudden stoppage in the and some re-drawing of diagrams, but I to put feet down during stops in flow of articles coming in. Werner Stiffel's would not like to have to do the whole traffic? construction plans required translation issue.) 2. Considering the benefits of the from German, and the indefatigable Theo I will do my editorial comments and Zzipper fairings, would it be Schmidt, who contributes materially to reviews on weekends and evenings, and worth the trouble to extend it almost every issue, volunteered from eventually send them to Marti Daily, who farther back than the rider's Switzerland. For the translation from the gets all the diskettes converted to a knees or hips? Dutch, I asked Ellen Warner of Oklahoma Macintosh format. Then she sends them 3. If carried all the way back past a City, where she rides an Avatar 1000. Her to Kim Griesemer at The Professional fairly wide seat and package photographs have appeared in previous Edge for the production lay-up and rack, how should it be termi- issues. It seemed highly desirable that her camera-ready copy. This is a major task. nated without going behind the many talents be tapped for HIuman Power; Kim has to arrange all these diverse rear tire? I frequently carry it accordingly, she and I were wed on pieces and photographs and diagrams so indoors by standing it up on its December 30, 1988. How else may I show that we end up with exactly 20 or 24 rear wheel. Many cars have my dedication to the cause of HPVs? pages, and so that the issue is easy to some sort of turned-up fin across Probably not all of these pieces will read. Newspapers have lots of little the back to do something (pre- appear in this issue. For an explanation of "filler" pieces to make the task easier. We sumably beneficial) to the the uncertainty, read on. have very few. Kim often has to delay an airflow when the rear of the article because it can't be made to fit. She body does not taper to a line or How Human Power is sometimes retranscribes a piece to point. For a vehicle taller than it achieve a more balanced layout. Eventu- is wide, could there be a vertical Published ally a camera-ready copy is produced and fin on each side to accomplish Jean Seay has written something sent to Marti, who takes it to a printing something similar? Can the body about how she operates as editor of HPV and distribution house. Very little would be left open at the rear, or should News, and I would like to do likewise for get done in the IHPVA without the help it be closed; if the latter, where is tHuman Power. Ideally I would be sent of our intensely dedicated president. the best location of an exhaust contributions and, every three months, I What might seem to you to be a vent? would select the most scintillating for the simple job takes many people a great deal (On the topic of wheel-suspension next issue. Actually, only a few contribu- of their spare time. Forgive us if some- systems for recumbents) I would like to tions come unsolicited. I phone and write times we slip in some respects. offer my experience with an alternative. I to many people to ask for papers and purchased my DeFelice after a short ride articles (if there's a difference it is some- to determine the required frame size. thing to do with technical or scientific A Human Power Index However, as I became more confident content) and send a set of guidelines on after some weeks of riding it, I found that how we would like material to be written In August I finished a longstanding I occasionally pedalled hard enough to and reproduced. About a quarter of these goal: to index all the articles that have stretch the nylon seat fabric sufficiently to actually send something. (More estab- appeared in Human Power since it first push the straps against the rear tire (the lished journals have room to publish only appeared ten years ago. It is reproduced fabric is in front of the seat-frame tubes, a quarter or less of what is sent to them). I on pages 19 and 20. Just after I finished it, and the straps are behind). I decided I edit everything that I believe needs Marti Daily sent me a categorized listing could gain the required clearance by changes to bring about more clarity or made by an unknown (to me) hero. I will replacing the fabric with a lawn-chair- grammar, trying to keep our overseas try to incoporate this into an expanded style cord wrapping, but arranged in a readers especially in mind (many HPV index later, and acknowledge her/him figure-eight pattern around the frame so enthusiasts write in a racy vernacular that then. -Dave Wilson 1I that the cords crossed in the middle. Since is wholly impenetrable by most non- the backrest must resist the force of Americans), and occasionally I may pedalling on a recumbent bike, I further shorten something that seems too long. If Letters to the Editor strengthened the seat by using polypro- there are major changes, I send a copy pylene rope, which does not have the back to the author(s) to check that my elasticity of nylon. For the lower part, alterations are acceptable, or I ask her/ As the recent purchaser of a DeFelice which supports the major portion of the him to do some re-writing. When a major recumbent, I have wondered about the rider's weight, however, I used nylon for contribution (as distinct from a letter or possibilities of making some sort of its slight elasticity. The result was totally news item) comes in good time, I like to simple enclosure that would improve air satisfactory: the backrest stays where it send a copy to one or two people working flow and exclude rain. It would have to should, and the nylon "seat" allows in the same area to ask for comments, and be simple enough for commuting service, several inches of vertical movement of the to give the author(s) an opportunity to and not appreciably increase the overall "U"ridpr' V hnbclVeiuuJ withIstI -1.. renee-truvt *V-tn ..h - Ifrmn . AA- n l respond. If a contribution is not on a dimensions. Some sort of plastic sheet additional benefit is that the "seat" and diskette, Sabina Rataj, our generous suite over a framework of wood strips starting (continued on page 15) 7/2 Human Power 3 Vibrational Stress on Cyclists by Rainer Pivit

corresponding designation in the ISO for the other, slower vehicles at the ABSTRACT CLA_,,I- ..., ... 1 - ALc..... LA-; Ddranluaru-- useu to get exposure-Ime rest of the narrow street-, The vibrational stress on bicycle riders limits for health or capacity of reaction or * brick-stone pavement with old flat with different bicycles and on different (cycle comfort impaired. In the ISO standard the stones (Marschweg), and track) surfaces was measured. Rough surfaces limit of reduced comfort is identical to the * new (Damm), of typical West German city cycle tracks VDI, the German limit of reduced capa- * concrete-stone pavement in a figure- nearly always impairperformance and even city of reaction is called exposure limit in Y pattern, (Staugraben)-widely sometimes the health of the rider. Suspension ISO standard, and is the upper limit. used in the inner city area-and systems can reduce vibrationalstress. There is no limit of health impaired in the * rectangular shaped (Carl-von- ISO Standard; vibration should always be Ossietzky-Str. cycle track)-this kind INTRODUCTION below the exposure limit (ISO) or limit of of pavement is used on nearly all In Oldenburg, a town of 140,000 in- reduced capacity of reaction (VDI). new cycle tracks-, habitants in the lowlands of North West The frequency response of (wo)man * asphalted surfaces of cycle-track Germany, bicycle traffic plays an impor- and the exposure-time limits are empiri- quality (Freibad cycle track), tant role in the traffic. In the inner city cal results. This method is very similar to . country-road quality (Kuepkersweg) about 10% to 25% of the traffic is done by the standardized measurement of loud- and bicycles. All major streets have cycle ness. But (wo)man has a different fre- · highway quality (Carl-von- tracks on the sidewalks. The situation of quency response concerning different di- Ossietzky-Str. drive way). the bicyclists is not as good as in the rections and different parts of the human We repeated the measurement with Netherlands but better than in most body. The hand-arm-system is, independ- six different vehicles: a roadster bicycle, German towns where only motorized ent of direction, most sensitive between 8 two touring bicycles, a Moulton bicycle, traffic is promoted. and 16 Hz. The maximum sensitivity for an OLF (Oldenburger Leichtfahrzeug = The traffic safety for the bicyclists in vibration in the direction of the spinal Oldenburg Lightweight Vehicle) and a Oldenburg is not better than in towns column of the body lies between 4 and 8 car. without sidewalk cycle tracks. The ac- Hz. The roadster bike was similar to the cidents happen at the crossings instead of typical bicycles in the Netherlands and is along the street as in towns without cycle MEASUREMENT the type most commonly used in Old- tracks. We measured the acceleration at the enburg. The tires were 37-622 mm (28 x 1- Most cycle tracks in Oldenburg are handlebar of the bicycle and at the under- 3/8") at 320 kPa (45 PSI).The saddle has made of concrete bricks because they are side of the saddle in direction of the back- large pressure and tension springs. The cheap and easily removeable for excava- bone. The signals of the sensors were diamond-framed bicycle weighed 17 kg, tion. Riding on those surfaces is not very amplified and encoded to a PCM-system the rider 80 kg. comfortable, but bicyclists are forced by on the bicycle and sent to a data tape Both touring bicycles had tires of the law to use them and are not allowed to recorder in a nearby car by HF-telemetry. size 28-622 mm (26 x 1-1/8") at 600 kPa ride on the smoothly asphalted roadway The data were evaluated with electrical (85 PSI) front and 700 kPa (100 PSI) rear pavement. filters corresponding to the frequency and an 'anatomic' saddle without springs. As a small group of physicists at the rating of the ISO and VDI standard. The bicycles differ in the position of the University of Oldenburg we are working Because the standards allow the handlebar, wall thickness of CrMo steel on bicycles and HPVs. In order to initiate interpretation only of signals lasting tubes and weight. On no. 1 the rider's a public discussion about cycle-track longer than 1 minute time we cannot arm had an angle of approximately 70 quality we tried to quantify vibrational make statements about the effect of single degrees to horizontal, no. 2 was with 45 stress on the rider. The method we used is bad spots on cycle tracks like potholes degrees more at the standard position on standardized by international ISO stand- and very bad transitions between cycle touring bikes. The wall thickness of the ard 2631 and German VDI (Verein track and driveway at crossings. tubes of no. 2 were thinner (exact dimen- Deutscher Ingenieure = Society of We carried out the measurement on sions unknown). Bike no. 1 weighed 15 kg German Engineers) standard 2057. These eleven different surfaces: and its rider 80 kg, no. 2 14 kg and 72 Kg. standards are mainly used on tractors and * a very old pavement of irregular field The Moulton bicycle was an AM 7 other machines where the operational stones (Hochhauser Str. flank), with its 17" tires at 700 kPa (100 PSI). The staff is exposed to vibrations. According · pavement of small (Werbachstr.) and suspension system is at front a weakly to the standards the acceleration is * normal cobble-stones (Elisabethstr.), dampened steel spring and at rear a measured at the interface with the rider. · very old brick-stone pavement with rubber-block spring with internal damp- The acceleration is then filtered according stones on end (Hochhauser Str. ing. Resonance frequency front and rear is to the frequency response of vibration of middle)-this was an historic cycle approximately 3 Hz. It had the same the human body. German VDI standard track as they were built in Oldenburg saddle as the touring bicycles. Weight of calls the resulting effective value the K- at the beginning of this century: 0.4 the bike was 14 kg and of the rider 80 kg. Value. K-Values go linear with the accel- m wide smoother brick-stone pave- The OLF is a three-wheeled recum- eration but differ with frequency. In the ment at the middle of the street for bent prototype built by our bicycle VDI Standard this K-Value--there is no bicyclists and field-stone pavement research group (see Human Power, 4 Human Power 7/2

Constructing a Fairing Mold Plug byGregTrayling

This article is reprinted with permission from - Wheel the NorthWest Human Powered Vehicle Front View Association. It originally appeared in its Nov- Dec, 1986 newsletter. 20 If you're looking for an accurate and inexpensive method of building a sturdy, light-weight plug to make a molded Figure 2 Figure 5 fairing, try the following method which I profile. Trace two critical stations, as as the mixture begins to foam, pour it used to make the fairing for the Paragon. shown in Figure 3, and interpolate the between the plug and such a barrier as a stations between. Keep in mind the height plastic sheet held against the edges of the Start With the Profile of the station from the profile. A NACA stations. Hold in place until foam sets, Start your design by drawing just the airfoil may be used to obtain the maxi- then peel barrier off. Fill all sections. profile that fits the rider and components mum station width. of the vehicle. Cut out a template of this profile using a thin board, like eighth- line of inch (3mm) Masonite. Sand the edges $50 ation at along the cut to ensure a smooth curve. ark 50 C 34) Draw vertical lines ten inches (250 mm) the per- apart which will be stations for 10 pendicular supports of the plug. Also draw a horizontal reference line; I suggest a line indicating 200 mm from the so Figure 6 ground. Nail a wood stiffener on the signed Smooth the form of the plug. Carefully -411-t sheet for reinforcing. Use thinner reinforc- Outline of Station Inxermeu 1I sand any bulging foam down to the near the tail where the form will at Mark 10 Station at ing Mark 30 station edges. If in doubt, sand to below taper. the fairing shape desired, rather than above. Fill in gaps, holes, and depressions Figure 3 by adding foam; simply paint on the When all templates for one side are liquid mix before foaming starts. finished, make duplicates. I suggest C. clamping the duplicates together and Apply a Hard Surface sanding the edges to make identical Lastly, make the hard surface for curves. molding with fiberglass and filler. Apply 0 o0 0o two to three layers of fiberglass mat with polyester resin to entire plug. Let harden. Apply a layer of inexpensive talc resin Figure 1 filler. Sand and repeat filler application until the plug is finished. Apply mold Find the Width at Points Along the wax and release solution to ready the Profile plug for molding. Next determine the shape of the fair- As an alternative to foam, all of the ing across its width. At such critical sections may be filled with carefully bent wheel axis and shoulders, points as the Figure 4 and taped pieces of cardboard. The cut out one side of the station templates. fiberglass and talc filler layers give ample Figure 2 shows a front view of a shape Glue the station templates to the profile; I rigidity and accuracy. which accommodates the wheel. When suggest using a hot-glue gun. Add such The method described above yields a desigining, note that 3mm (1/8 inch) will horizontal supports as shown in Figure 5. strong, light, and cheap plug. In addition, be added later by the surfacing layers Preview the overall shape, check that the fairing can be designed as the plug is over the whole plug. components fit, and adjust the design. built. This saves considerable time in visualizing the rider and vehicle compo- Design While Constructing Fill the Form with Foam nents from a scale drawing. All materials Make intermediate stations using the Next, finish the full form of the plug and technical support can be found at shape of the critical templates. One can with a blanket of polyurethane. First, tape your local lumber supply and fiberglass design while constructing, an advantage cardboard strips a half-inch (13mm) from shop. over constructing a preset design. For the edge and seal off to conserve foam. Greg Trayling uniformity, make all the templates curve Mix the two parts of polyurethane pour- P.O. Box 4454 into a 90 ° angle at the top and bottom. in-place foam. (Avoiding the vapors from Vancouver, BC V6B 3Z8 Measure the template height from the this mix requires a proper respirator.) Just CANADA O 7/2 Human Power 7

100 REM Propeller Design 28.11.87 650 PRINT DIA PITCH BT SPD PR SPD P IN P OUT ETA"; 110 REM By Theodor Schmidt 660 PRINT"ETA F THRUST CL(5) SLIP' 120 REM Input data thru variables at beginning of program 670 PRINT"(M) (M) (M/S) (RPM) (W) (W) (%) (%) (N)" 130 REM Program runs from low RPM to top RPM given by R1 680 R3=R1;R4=R2 and R2 690 FOR RR=R1TOR2 STEP INCR 140 REM in steps of "incr". Basic may take several minutes 700 VR=CIRCUM*RR/60 150 REM to work out first result. 710 I=1 160 Diameter = 0.50 :REM (Meters) 720 DELTA(I)=ATN(U/(VR*(I/10))) 170 Ptch=0.66 :REM (Meters) 730 ALPHA(I)=BETA(I)-DELTA(I) :REM ANGLE OF INCI- 180 U=1.5 :REM boat speed in m/s DENCE AT BLADE ELEMENT 190 Rl=100 :REM (RPM) 740 IF ALPHA(I)<-0.1 THEN R3=RR+INCR:GOTO770 :REM 200 R2=600 :REM (RPM) LIMITS PROGRAM TO POSITIVE LIFT 210 Incr=10 :REM (RPM) 750 IF ALPHA(I)>.26 THEN R=4=RR:GOTO780 :REM RE- 220 Blades=2 STRICTS BLADE LOADING 230 Header$="Y" :REM "Y"or "N" (prints out basic blade 760 IF 1<8.5 THEN I=I+1 :GOTO720 parameters) 770 NEXT RR 240 Range$="Y" :REM "Y"or "N" (Limits top RPM to low blade 780 IF RANGE$="N"THEN R4=R2 loadings) 790 FOR RPM=R3TOR4 STEP INCR 250 CH(1)=.075 :REM Chord at radial station 1 (near hub) in m. 800 VR=CIRCUM*RPM/60 260 CH(2)=.080 810 PP=0:PW=0:T=0 :REM POWER IN, POWER OUT, THRUST 270 CH(3)=.087 820 UR=U*(1+Q) :REM SPEED THRU DISC, Q IS SLIP FACTOR 280 CH(4)=.091 830 FOR I=1TO9 290 CH(5)=.091 840 UR(I)=U*(1+Q(I)) 300 CH(6)=.087 850 VR(I)=VR*(I/10) 310 CH(7)=.080 860 W(I)=SQR(UR(I)t2+VR(I)t2) :REM RESULTANT SPEED AT 320 CH(8)=.070 BLADE SEGMENT 830 CH(9)=.055 870 DELTA(I)=ATN(UR(I)/VR(I)) 340 DIM FF(16,14) 880 ALPHA(I)=BETA(I)-DELTA(I) 350 FOR K=1TO14 890 CL(I)=ALPHA(I)*5.75/(1+2/AR)+0.35 :REM COEFFICIENT 360 FOR J=OTO15 OF LIFT 370 READ FF(,K) 900 IF CL(I)<0 THEN GOTO1470 380 NEXT J 910 RE(I)=1E6*W(I)*CH(I) :REM REYNOLD'S NUMBER (for air 390 NEXT K replace 1E6 with 7E5) 400 PI=3.14159 920 X=ABS(INT)(10*CL(I)+0.5)) 410 CIRCUM=PI*DIAMETER 930 IF X>15THEN X=15 420 OPEN,4:CMD1 :REM TRANSFERS OUTPUT TO PRINTER 940 IF RE(I)<45000THEN Y=1:GOTO1000 430 TA=ATN(PTCH/CIRCUM):TD=TA*57.296 :REM TIP 950 IF RE(I)<105000THEN Y=INT(RE(I)/1E4-2.5):GOTO1000 ANGLE 960 IF RE(I)<212500THEN=INT(RE(I)/2.5E4+3.5):GOTO1000 440 SWPT AREA=PI*(DIAMETER/2)2 970 IF RE(I)<2E6THEN Y=12:GOTO1000 450 FOR I=1TO9 980 IF RE(I)<4E6THEN Y=13:GOTO1000 460 A(I)=CH(I)*DIAMETER/20* BLADES 990 Y=14 470 BETA(I)=ATN((PTCH/CIRCUM)/(I/10)) 1000 CD(I)=FF(X,Y)/1000 :REM PROFILE COEFFICIENT OF 480 A=A+A(I) DRAG 490 NEXT I 1010 IF CL(I)>1.2 THEN CL(I)=1.2 :REM PATHETIC ATTEMPT 500 A=A+A(9)/4 :REM TOTAL BLADE AREA TO SIMULATE APPROACHING STALL 510 BAR=A/SWPT AREA :REM BLADE AREA RATIO 1020 ID(I)=CL(I)T2/(PI*AR) :REM INDUCED DRAG 520 AR=(DIAMETER/2)T2/A*BLADES :REM BLADE ASPECT *1030L(I)--500*A(I)*CL(I)*W(I)T2 :REM LIFT RATIO *1040D(I)--500*A(I)*(CD(I)+ID(I))*W(I)t2 :REM DRAG 530 IF HEADER$="N'THEN 650 1050 T(I)=L(I)*COS(DE(I))-D(I)*SIN(DE(I)) :REM THRUST 540 PRINT "PROPELLER SIMULATION PROGRAM" 1060 F(I)=L(I)*SIN(DE(I))+D(I)*COS(DE(I)) :REM LATERAL 550 PRINT " ":PRINT:PRINT "BLADE NUMBER=";BLADES FORCE 560 PRINT"DIAMETER= ";DIAMETER; "M" 1070 PP(I)=F(I)*VR(I) :REM POWER IN 570 PRINT "PITCH = ";PTCH;"M" 1080 PW(I)=T(I)*U :REM POWER OUT 580 PRINT "SWEPT AREA = ";INT(SWPT AREA*10000+0.5)/ 1090 ETA(I)=PW(I)/PP(I) :REM EFFICIENCY 10000;"SQ M" *1100 CT(I)=T(I)/(500*DI*(I /10)*PI*U*U*DI/20) :REM COEFFI- 590 PRINT "BLADE AREA RATIO = ";INT (BAR*10000+0.5)/ CIENT OF THRUST 10000 1110 C2(I)=Q(I)*4*(1+Q(I)) :REM ALSO COEFFICIENT OF 600 PRINT "BLADE ASPECT RATIO- ";INT(AR*1000+0.5)/100 THRUST 610 PRINT 'TIP ANGLE= ";INT(TD*100+0.5)/100; "DEGREES" 1120 EF(I)=2/(1+SQR(1+CT(I))) :REM FROUDE EFFICIENCY 1 620 PRINT "STATION CHORD (M) ANGLE (DEGREES)" 1IIOU- ,n r',.lU=L _.1 / IrT VtL1)-1 630 FOR N=1TO9 * For salt water, replace 500 with 512. For air, replace 500 with 640 PRINTN;SPC(9);CH(N);SPC(9);INT(BETA(N)*5729.6+0.5)/ 0.625 100:NEXT N;PRINT 7/2 Human Power 9 1140 IF ABS(C2(I)/CT(I)-1)>0.05 THEN 840 1470 NEXT RPM 1150 T=T+T(I) 1480 PRINT#1:CLOSE 1 :REM CLOSES FILE TO PRINTER 1160 PP=PP+PP(I) 1490 REM THE FOLLOWING VALUES ARE READ INTO THE 1170 PW=PW+PW(I) ARRAY FF AND 1180 NEXT I 1500 REM REPRESENT CD AS A FUNCTION OF CL AND RE 1190 ETA+PW/PP 1510 DATA25,23,27,50,70,80,80,80,75,70,60,50,50,200,1000,1000 *1200CT=T/(500*SW*U*U) (RE<45000) 1210 EF=2/(l+SQR(1+CT)) 1520 DATA24,22,25,40,50,55,57,58,55,50,45,42,46,180,1000,1000 1220 Q=1/EF-1 (RE=50000) 1230 C2=4*Q*(1+Q) 1530 DATA23,21,23,35,40,46,46,46,46,46,42,38,45,150,800,1000 1240 UJ=U*(1+2*Q) (RE=60000) 1250 P$=RIGHT$(STR$(INT(DIAMETER*101)/100),5 1540 DATA22,21,22,31,35,39,39,39,39,39,37,35,41,140,700,1000 1260 PRINTP$;SPC(7-LEN(P$)); (RE=70000) 1270 P$=RIGHT$(STR$(INT(Pr*101)/100),5) 1550 DATA22,21,21,27,30,33,33,33,33,33,32,31,37,130,700,1000 1280 PRINTP$;SPC(7-LEN)(P$)); (RE=80000) 1290 P$=RIGHT$(STR$(INT(U*100)/100),5) 1560 DATA21,21,21,23,25,27,27,27,27,27,27,27,33,120,600,1000 1300 PRINTP$;SPC(7-LEN(P$)); (RE=90000) 1310 P$=RIGHT$(STR$(INT(RPM)),5) 1570 DATA20,20,20,20,19.9,19.5,19,19,19.1,19.5,20.2,23,30,100,600, 1320 PRINTP$;SPC(7-LEN(P$)); 1000 (RE=100000) 1330 P$=RIGHT$(STR$(INT(PP+0.5)),5) 1580 DATA19,16.8,18.6,18.3,18,17.5,17.2,17.3,17.8,18.3,19.2,21,28,84, 1340 PRINTP$;SPC(7-LEN(P$)); 600,1000 (RE=125000) 1350 P$=RIGHT$(STR$(INT(PW+0.5)),5) 1590 DATA18,17.7,17.2,16.5,15.6,15,14.6,14.8,15.3,16.2,17.3,20,25, 1360 PRINTP$;SPC(8-LEN(P$)); 80,500,1000 (RE=150000) 1370 P$=RIGHT$(STR$(INT(ETA*100+0.5)),5) 1600 DATA17.5,16.3,15,13.6,12.7,12,12,12.4,13.6,14.6,16,18,24,60, 1380 PRINTP$;SPC(7-LEN(P$)); 400,1000 (RE=175000) 1390 P$=RIGHT$(STR$(INT(EF*100+0.5)),5) 1610 DATA1 7,14.5,12,10.2,9.5,9.3,9.4,9.8,10.8,12,13.8,16,21,42,84, 1400 PRINTP$;SPC(8-LEN(P$)); 168 (RE=200000) 1410 P$=RIGHT$(STR$(INT(T+0.5)),5) 1620 DATA12,10.3,9.3,8.6,8.3,8,8,8.3,9,10,11.1,13,15.5,20,40,80 1420 PRINTP$;SPC(7-LEN(P$)); (RE<2 106) 1430 P$=RIGHT$(STR$(INT(CL(5)*100)/1 00),5) 1630 DATA7,7,7,7,7,7,7,7.1,7.5,8,8.8,10,12,15,20,30 (RE<4 10 ) 1440 PRINTP$;SPC(6-LEN(P$)); 1640 DATA6.2,6.2,6.2,6.2,6.2,6.3,6.4,6.6,6.9,7.3,8,9,10.1,1 2,14,17 1450 P$=RIGHT$(STR$(INT(Q*1 000+0.5) /1000),6) (RE<4 106) 1460 PRINTP$

Dlf P.TCH i-SFF F i t, Propeller data taken from [M] [M] [M/S,]; [EPMV :KJ HUMAN POWER .4 .46 Z 220 l .e-- :E-O? .4- .46 Z.2 27 13 .8 - E-el page 11 vol. 6 no. 2 (Summer, 1987) .4 .46 2. 240 46 .1L3 .c13 .4 .46 L.2 250 65 54 *compare with results In Table 1, page 11 .4 .46 2.2 260 88 74 .L4 .327 .4 .46 2.2 270 113 94 28 .034 PROPELLERSIMULRTIOH PROGRAM .4 .46 2.2 28e 19 :!5 74 92 1 43 041 .4 .46 .- 29 168 138 -75 91 4 ,* .4 2.2 300 19 2.2 6- TIrMETER = .4 M Bl .4 46 310 ;--h = .44 . .46 _. _ _. t iE T RE = .1257 SQ .4 .46 2.2 33 307 236 .46 3 091 BLiE ARERRMTIO = .2821 .4 2.2 348 348 265 .,4.3- .35.Q49 BLDE RASPECTRRTIO s 3.15 .4 .46 2.2 350 392 294 .4 .46 2.2 368 438 TiP 2.11 324 74 EZ 70 :47. .5 .a132 AHGLE= DEGREES a. 9- 33_. .5'3 ,091 STfTION CHORD CM] ARNGLE[DEGREESi .4 .46 2.2 370 488 355 73 9 16 64 84 223 .5.56 .505.14 .4 .46 2.2 388 340 386 72SZ776 987916 67134176121 1 .o .08340 62.84 74 se 147 .4 .46 2.2 390 596 421 7173 85es 191162 2 .08940 52.55 7271 85Bs ISI176 .61 .119 .4 2.2 480 3 ,? .019 44.71 .46 655 455 7870 8787 20727 .63 .1279 .4 .46 2.2 4"a 717 491 68 86 223 .75 .139 4 . .0874 38.33 Rjq i ortc .67 .143 .4 .46 2.2 420 782 527 67 86 240 .71 .169 .4 .46 2.2 438 851 565 66 85 257 .73 .179 56 ..1, ..0698B 33.j28.98 7 .il .0569 25.53 .4 .46 2.2 440 923 603 65 84 274 .75 .19 .4 .46 2.2 4se 998 8 . .84044 22.67 643 64 83 292 .76 .2 9 .1 .8293 21.42

.4 .46 2.2 270 113 94 83 97 43 .28 .834 DIP PITCH BT SPD PR SPD P IN P OT ETA ETR F THRUST a(s) C [Mi [M] IM/S] [RPM] C[W) W] %1 [1% N] (S1 .4 .46 2.2 271 116 97 84 97 44 .29 .035 .4 .46 .5 188 11 7 62 84 14 .74 .188 .4 .46 2.2 272 118 99 83 97 45 ,29 .036 .4 .46 .5 118 16 9 59 81 18 .82 .237 .4 .46 2.2 273 121 101 83 96 46 .3 .036 .4 .46 274 123 .4 .46 .5 128 21 12 5 78 23 .87 .287 2.2 103 83 96 47 .3 .037 .4 .46 2.2 275 126 185 B3 96 48 31 .4 .46 .5 130 27 14 53 75 29 .S2 .339 - ,3s .4 .46 .s 148 34 17 58 72 34 .96 .392 ¢ .4 .46 2.2 276 129 107 83 96 49 .31 .~ .4 .46 .5 158 43 20 48 69 40 .99 .445 4 .46 2.bZ I'l 132 1 9 83 96 58 .31 .630 .4 .46 .s 168 52 24 45 67 47 1.82 .5 .4 .46 2.2 278 134 111 83 96 51 .32 .04 .4 .46 .5 178 63 27 43 64 54 1.e4 .55 .4 .46 2.2 279 137 114 83 96 52 .32 .041 .4 .46 .5 188 77 30 39 63 68 i.04 .595 .4 .46 2.2 280 148 116 83 96 03 .33 .842 1.4 .46 .s 19e 91 33 36 61 66 :. .643 % ,4S .5 200 106 37 ,s 59 74 100 .697 T .4 .46 .3 218 126 41 32 57 82 1.09 .746 .4 .46 1 188 1 8 13 100 0 .62 IE-03 .4 .46 .s 228 151 44 29 56 89 1.11 .79 .4 .46 1 11l 5 4 72 99 4 .15 .014 .4 .46 .5 238 161 l1 31 54 1ol 1.12 .864 .4 .46 1 120 10 8 78 97 8 .26 .029 .4 .46 .5 240 183 56 30 52 1!1 1.13 .92 .4 .46 1 130 15 12 78 96 12 .35 .84s .4 .46 .5 258 206 61 29 51 121 1.14 .977 .4 .46 1 140 22 17 77 94 17 .43 .863 .4 .46 1 138 38 22 75 92 22 .51 .882 .4 .46 1 168 39 28 73 91 28 .57 .102 .4 .46 1 170 49 35 71 89 35 .62 .122 .4 .46 .4 .46 .81 100 19 0 1 4 19 1.2 27.334 1 188e 60 41 69 87 41 .67 .144 .4 .46 1 198 73 49 67 49 .71 .166 .4 .46 = .01 120 32 O 1 3 28 1.2 32.916 86 8 .4 .46 1 280 .4 .46 ,.01 140 51 8 1 3 38 1.2 38.485 87 56 65 84 56 .74 .189 183 .4 .46 .81 168 76 0 1 2 50 1.2 44.881 f1¢.4 .46 1 210 65 63 82 65 .79 .213 .4 .46 1 2ZZ 121 74 61 81 74 .81 .237 .4 .46 .01 18 107 1 1 2 63 1.2 49.666 .4 .46 1 230 140 83 59 79 83 .83 .261 .4 .46 .1 200 111 I 1 2 82 1.2 36.77 .4 .46 .4 .46 -=.81 220 144 1 1 2 1 100.2 62.563 1 240 162 93 57 78 93 .86 .286 .4 .46 1 250 185 183 56 76 103 .4 .46 -.81 248 173 1 I . 121 1.Z 69.012 .88 .312 10 Human Power 7/2 Prone-Position Recumbent Table 1 Bicycles Means and ranges of ratings of prone-position human-powered vehicles by designers and riders* (continued from page 1) Category Own Best Machine Prone Machines categories of items on the questionnaire in General pertained either to their "most successful prone-position HPV design" or to "prone- Comfort position HPVs in general". Items in each General comfort 1.9 (mean)(1-4)(range)** 1.9 (1-4) category were further divided into areas of Head/neck comfort 1.4 (1-3) 1.5 (1-4) comfort, power, and control, and in each Leg comfort 2.4 (1-4) 2.4 (1-4) case, respondents were asked to compare Visibility 1.8 (1-2) 2.1 (1-3) prone recumbents to conventional racing bicycles. A five-point scale was used for Power each specific item with "1" being poor, "3" Peak (short-term) 3.5 (2-5) 2.3 (2-5) being the same, and "5" being excellent as Long-term power 2.4 (1-5) 2.5 (1-5) compared with a conventional racing bi- Hill-climbing power 2.3 (1-4) 2.3 (1-5) cycle. Respondents were asked also to comment on each of the above areas and to discuss the advantages and disadvantages Control of the prone position. The author has built Control when turning and ridden four prone recumbent bicycles corners 2.2 (1-3) 2.3 (2-3) and also completed a questionnaire. Nine Control on rough completed questionnaires were received. terrain 1.5 (1-2) 1.4 (1-2) Means and ranges for each of the scored responses were calculated and comments * number of respondents = 9 relevant to each item are included in the ** rating scale: 1 = poor, 3 = same as conventional , results. 5 = excellent RESULTS The means and ranges of ratings for conventional position and that having the advantage of the prone recumbent posi- each item are included in Table 1. General shoulders against solid supports aided in tion. This position allows the possibility comfort received a mean rating of 1.9 (as the production of peak power. It was of a simple, lightweight vehicle design compared to a standard 3.0 rating for a noted that training in the prone position utilizing standard bicycle parts (no long conventional bicycle). All components of is necessary to improve efficiency in this chain paths, etc.). Two of the respondents comfort, including visibility were gen- position. The inability to change positions felt that the prone position felt natural, erally rated as inferior to a conventional while in the prone position was noted to powerful and aggressive. Most respon- bicycle. Most respondents commented on be a disadvantage as compared to the dents felt that it is possible to produce the need for comfortable supports rigidly conventional position where the rider can more peak, short-term power in the prone attached to the frame for the pelvis and stand for hill climbing, stretching, etc. position. shoulders. All used toe clips to support the Two of the respondents utilized the prone Comments about disadvantages of feet. Some used a padded support for the position to facilitate hand and foot power the prone position varied greatly and chin. One used elastic supports for the to increase peak power for short periods depended upon the respondent's experi- knees. Several respondents commented on of time. ence and type of machine. Several com- the rider's difficulty in turning his head Control was rated at a level similar to ments were made about the potential while in this position to see directly to the comfort, moderately inferior to the con- danger in a head-first, "head-on" colli- rear. ventional position. Two of the sion. Respondents frequently noted the Power generated in the prone position respondents built three or four-wheeled disadvantages in maneuvering their long- was generally rated as slightly inferior to machines and did not comment on con- wheelbase, low-ground-clearance prone that in the conventional position. There trol. Two of the respondents with a great machines. The low profile of these was, however, a great deal of variability in deal of prone bicycling experience (GJ machines was also noted to make them the opinions. Brief ergometry testing by and CD) felt that cornering ability of a hazardous when on the road with auto- Chet Kyle showed long-term power to be properly designed prone recumbent was mobiles. Reduced comfort, poor visibility, an average of 8% less than the conven- equal to that of a conventional bicycle. All inability to use "body English" in balanc- tional position. While most respondents of the respondents used low-slung, long- ing, and inability to "post" to avoid shock agreed that long-term power was slightly wheelbase designs and stated that the input were also noted by some respon- decreased, the respondent with the most long wheelbase and low ground clearance dents. experience (GJ) felt that his ability to were disadvantages in some maneuver- produce prolonged power in the prone ing situations. Control over rough terrain DISCUSSION position was excellent, and that long uphill was a consistent problem. All but one of the respondents de- climbs were no more exhausting than on a All of the respondents cited low signed their prone recumbent machines standard bicycle. Most felt that peak frontal area and the potentially low primarily for top-speed competition. power was slightly better than in the associated aerodynamic drag as the chief Thus, their experience and opinions must 7/2 Human Power 11 speed land vehicle might benefit from the low frontal area and potentially low aero- Frontal Area Versus Surface dynamic drag which are possible with the prone position. The prone position might also be best for human-powered subma- Area-Prone or Supine? rines because drag problems are multi- plied many times under water. The over- by Chester R. Kyle all combined opinions as summarized in Table 1suggest, however, that the prone position is inferior to the conventional David Gordon Wilson asked me to that minimum frontal area will produce bicycling position in nearly every way. It comment on a question posed by Allan minimum aerodynamic drag. This is true should be kept in mind that those indi- Abbott's survey of prone recumbent up to a point. Hoerner (Aerodynamic Drag, viduals who were the most enthusiastic designers. The question is the relative 1965, p. 6-16), reports that with symmetric about the prone position for human- importance of frontal area versus surface streamlined airship shapes, the optimum powered vehicles were also the individu- area in achieving low aerodynamic drag. length-to-fineness ratio is about 5. With als with the most experience and greatest Although I can't answer this exactly, very careful design of the profile, others success with prone recumbents. Future some discussion should help clarify it. find that this ratio can be from 3.5 to 5. designers considering the use of the Since 1975, when competitors sys- This means that as the ratio of the length prone position for human-powered tematically began trying to build the to width increases, the skin friction vehicles should pay particular attention world's fastest human-powered vehicle, becomes more significant compared to to the successes of these experienced various schemes have been used to pressure drag, until an optimum occurs designers. achieve the lowest aerodynamic drag within a certain family of shapes. The author wishes to acknowledge possible and the highest speed. To do this The proximity of the ground plane the following individuals who contrib- HPV builders have generally employed complicates the matter, but it is obvious uted their time, experience and knowl- efficient aerodynamic shapes and mini- that by increasing length, larger surface edge to this paper: Steve Ball, Cole mum frontal area. The belief is common areas will sooner or later cause an in- Dalton, Greg Johnson, Chester Kyle, Fred Markham, Gardner Martin, Paul Van Valkenburg, and Kurt Wold. VEHICLES TESTED GIVING THE RESULTS IN FIGURE 1 MAX.SPEED mph Allan V. Abbott 1 Paul Van Valkenburgh racing bicycle, bare P.O. Box AA 2 ...... with Aeroshell fairing and bottom skirt 46.51 Idylwild, CA 92349 (20.79 m/s) Allan Abbott was the first president of the IHPVA; he held the paced bicycle speed record 3 Mario Palombo , rear steering, until recently; offered the Abbott prize for the no fairing first IIPV to exceed 55 mph; developed the 4 "...... faired but exposed rear 44.38 (19.84) Flying Fish hydrofoil with Alec Brooks, and is Chester Kyle standard racing bicycle, faired 46.46 (20.77) a physician.-ed. Li O

Reviews * Paul Van Valkenburgh prone , As reported in the editorial com- + hand-and-foot powered 49.38 (22.07 m/s) ments, Bike Tech ceasing publication--or - )0=, -_ perhaps has already done so (as of December 1988). There have been three A Steve Ball prone tricycle, linear-actioi issues-April, June and August, 1988, hand-and-foot powered 54.69 since our last review. In April there were =Co° (24.45 m/s) articles on do-it-yourself grease fittings, the Campagnolo Synchro shifter, a short U Bill Watson supine bicycle 46.12 note on human power that continues in the next issues, an article on clincher tires i t --a (20.62 m/s) (the successor, on mountain-bike tires, J Eric Edwards supine tricycle, rear-steering, appears in June), and a piece by editor oval pedal travel 50.72 Bruce Feldman on the Long Beach show: .=C) Z (22.67 m/s) "Steel springs back". He refers to bike 0 - , frames. I for one am relieved. Aluminum- The coast-down tests, 1977-1984, involved two streamlined bicycles, alloy frames, and particularly forks, scare two prone recumbents, and me if they are subjected to hard use. three supine recumbents. CRK/DGW 89.01 (continued on page 16)

7/2 Human Power 13 1 Van Valkennurgh racing bicycle, bare, 1977 If the rolling friction is disregarded, 2 " Aeroshell faring and botomnskirt, 1977 then the Dragonfly has the lowest aero- L " prone quadracyle, 1977 1978 dynamic drag of any of the vehicles meas- 3 Palombo supine tricycle, bare, 1976 ES- wit fairing, exposed heels, 1976 ured. The highest would be the Palombo bicycle, streamlined sus supine tricycle, 1984 supine tricycle closely followed by the -S bicycle, 1978 .y prone tricycle. 1984 VanValkenburgh standard bicycle with 20 the Aeroshell fairing. The other four

.4 machines are approximately equal. Coast- 3 2 down tests therefore support the conclu- sion that a prone machine can have a very low aerodynamic drag.

AST-TS However, a well-designed supine IS0 tricycle such as Don Witte's Allegro (62.98 I2 MPH) probably has as low a frontal area as the Dragonfly, and it is probably some- uT-eWN T vehles, what shorter as well. Abbott's prone bi- ,uan-poered ehicles. cycle however holds the record for mini- to.a. rag versus speea. Ik5s r r mum frontal area at only 3.3 square feet. 65 tO 15 20 25 30 35 40 45 i , Even though Abbott's top speed was low- U S 10 5 etLj/s,,e 20 er than some of the others, all of the other 5 PEE D C.8eYE I 12k/ Do' 0119 vehicles mentioned were ridden by Figure 1. Coast-down tests, streamlined human-powered vehicles, total drag versus speed. nationally ranked bicycle racers. Abbott rode his own vehicle, so it is unclear what crease in drag, no matter how small the Using high-speed coast-down tests the potential of his machine really is. frontal area. Actually the most successful between 1976 and 1984, I measured the Besides using the prone position to HPVs today are relatively short. Gardner total drag of seven streamlined HPVs. achieve minimum frontal area, designers Martin's Gold Rush, (a supine bicycle and The measurements were done on smooth have often resorted to linear pedal travel. the curent world-record holder- 65.49 asphalt or concrete pavement (the Los Because of the increased complexity of MPH), is only 8 feet long. It has a frontal Alamitos Naval Air Station Runway and linear mechanisms the lower mechanical area of 5 square feet, and an equivalent the San Gabriel River Channel, Califor- efficiency could hamper speed. No one length-to width ratio of only 3.2. Table 1 nia). The results are shown in Figure 1. has measured the mechanical or biomech- gives the dimensions of the Gold Rush With a coast-down test, all components of anical efficiency of linear-pedal-travel plus Steve Ball's tricycle Dragonfly, (a drag are summed including rolling-bear- mechanisms versus the conventional prone recumbent with hand and foot ing friction, rolling-tire friction, and air circular motion, so their effect on speed is power and linear pedal travel, top drag. The curves show that some of the uncertain. speed-54.7 MPH), Allan Abbott's prone machines had a very high rolling drag Another strategy to minimize frontal bicycle (50.44 MPH), and several others. (extrapolate the curves to zero speed). For area with is to decrease the re- Five of them are also listed in Figure 1. example, the rolling drag of the Palombo quired width between the paired wheels. From the table, it is apparent that tricycle is about double that of the rest, Two schemes have been used. Eric there can be a considerable advantage to a probably due to a sticky sealed bearing, Edward's Pegasus drives the two front prone recumbent in achieveing low fron- or a gummy freewheel. Also, the curve wheels and uses rear-wheel steering. He tal area compared to a more upright for Steve Ball's Dragonfly shows a higher solved the rear-steering stability problem supine bicycle. However as to actual rolling friction than the others. This is by using negative trail, dampeners, and a comparative drag, the advantage is probably due to a friction-clutch mecha- very limited steering angle. Don Witte's questionable. nism used in the linear drive. Allegro reversed this plan by combining

Table 1

Vehicle Length Width Height Frontal Area L/W

Gold Rush Supine 8 feet 19 inches 51 inches 5.0 square feet 3.2 Abbott Prone 12.5 feet 18 inches 31 inches 3.3 square feet 6.1 Dragonfly Prone 10.2 feet 22 inches 30 inches 4.4 square feet 4.3 VanValkenburgh Standard Bike 7.3 square feet Kyle Standard Bike 8.3 feet 20 inches 62 inches 7.6 square feet 5 Palombo Supine Tricycle 5.0 square feet VanValkenburgh Prone 5.0 square feet

14 Human Power 7/2 the drive and steering in the single front the seat frame as the one-piece fabric did. complexity vs. weight would be very wheel, and by allowing the rear pair to Theoretically, the unsprung weight is interesting. freewheel. much greater in this case. In practice, the Practical results have shown that a total weight of a bike frame is much less Milford S. Brown slightly higher frontal area does not that that of a car, or even a motorcycle, 7308 Gladys Avenue necessarily result in a higher drag. The which has a rear suspension similar to the El Cerrito, CA 94530 two fastest HPVs in the world are supine Moulton upright bike, the German Radius bicycles, Gardner Martin's Gold Rush, recumbent, and a similar U.S.-made one. (I combined two letters here -ed.) 65.49 MPH; and Tim Brummer's Light- While it would not be possible to suspend ning X2, 64.19 MPH). the seat of an upright bike independently Probably the breakthrough that led of the pedals, the bounce motion of the This is a late comment on Ramondo to these high-speed supine bicycles was recumbent rider is perpendicular to the Spinnetti's article, (vol. 6/3), because I the development of what could be called direction of pedalling, analogous to the was busy in Greece on the Daedalus crew. the Land Shark-Nosey Ferret-Lightning- swinging rear suspension that pivots First, I agree with the concern expres- Infinity-Gold Rush shape. Except for the approximately around the center of the sed by Prof. Bussolari in his comments Land Shark, each of the above vehicles driving sprocket. When the front wheel that it is hard to draw conclusions from a has won the Speed Championships. This hits a bump, the entire bike pivots around single-subject experiment, especially shape consists of a low, narrow, rounded the rear axle, but with the nylon-rope seat when the test subject is the experimenter nose, tapering upward and back and the inertia of the rider's body allows it to and author of the paper. It would be very reaching the widest point at the rider's follow later, probably after the wheel has useful to get more data with some other shoulders. From this point, the contour passed over the bump and returned riders on the apparatus. tapers back to a sharp trailing edge. As almost to its previous road level. Thus the I will, however, disagree to an extent far as I know, this shape was not pat- body is not required to deflect to the with (Steve) Bussolari's concerns about terned on any wind tunnel or theoretical extent that it would on a more rigid seat the differences in rider position. I feel that model, but was based on logic and eye- (the rope seat has considerably more it is quite valid to choose any suitable ball intuition. The first of this generation flexibility than the original fabric, which position for the reverse-pedalling tests, was probably Danny Pavish's Land Shark in turn is much more flexible than the with the possible restriction that it be in 1980, using the Easy Racer bicycle as a customary bike saddle). A similar series practical for actual bicycle applications base. Over the years, the shape has been of reactions follows as the rear wheel then (which this position clearly must be, refined by numerous designers until it is hits the bump, except that the bike now based on the photograph of the author's superbly efficient in many forms. Accord- pivots around the front axle. bicycle in issue 7/1). There is no reason to ing to Danny Pavish, it leads to laminar I do not know how effective such a arbitrarily restrict the reverse tests to a flow over the forward part of the fairing, seat would be on a tricycle, where the position that may be unsuitable. On the minimizing air-friction drag. outer wheels can impart both roll and other side of the issue, it could conceiva- One conclusion that can be drawn pitch to the frame unless they are sus- bly be that better results would be obtain- from the above discussion is that frontal pended independently, as on that in HP ed for forward pedalling using some area is not the most important factor in vol.7/1. That vehicle is intriguing as a superior seating position that has eluded designing a successful human-powered mechanical engineering project, but in frame designers, but the author certainly vehicle. Total aerodynamic drag, stability, comparison to my suspension of the rider, cannot be faulted for using the "stan- visibility, biomechanical practicality and I wonder if it is worth the additional dard" position as his basis of comparison. efficiency, mechanical efficiency, and low weight and complexity. One must re- The biggest problem that I find, weight are some factors that can be of member that in a car, the body constitutes however, has to do with the lack of foot equal importance. It is a pity that more the major portion of the sprung weight, restraint on the test apparatus. If the experimental information is not available; with two passengers in a small car photographs accurately represent the test however, the typical designer is often too comprising some 15% of the total, where- setup, then it would seem that the bi- busy building and testing, and can't often as a bicycle is just the opposite-the bike cycles had no toe clips. The force-vs.- afford the time to write about her/his alone is a similar fraction of the weight of crank-angle graph would seem to be observations and findings. For this the vehicle plus rider. Isolating the body consistent with this. (The bicycle in the reason, Allan Abbott's article is very from the wheels of a car allows much of photo in issue 7/1 also seems not to have much appreciated. I hope that it will lead the mass to move less than the wheels. toeclips.) It would seem quite possible to others of a similar nature. On the other hand, the controlled that with no foot restraint, greater power Chester R. Kyle flexibility of the trike shown may reduce could be obtained with a reverse ped- 9539 Old Stage Rd. the required strength of the support alling motion; however, almost all Weed, CA 96094 O members because they allow the wheel applications that would attempt to extract deflection by a bump to be dissipated maximum power would use some form of through compression of the spring ele- toe clips, and I feel that toe clips (espe- Letters to the Editor ment, and thus do not need the rigidity to cially if used with cleated shoes) could (continued from page 3) transmit the motion to the rider (compare have a dramatic effect on the data, as they the dimensions of the A-arms of the allow the rider to pedal "in circles", lightweight commuting vehicle in HP rather than just pushing down on the vol.7/1 with the si7P nf th tnn ancl nwn backrest portions are not connected; thus ...... ~ v.- -.~ L.. -,.- pedals. the vertical movements of the rider do not tubes of a diamond frame). A complete I have wondered about the efficiency cause the backrest covering to slide down engineering study of this aspect of of reverse pedalling for some time, and in 7/2 Human Power 15

SHARPY- CYCLE

LENGTH GL0 I BEAM, A, 3 LG D AFT-,wU L O-3 ZMAT7 Eat t'-7U

__i -, f--- -r- - -i- '_- 5EC71ONAL ARE S 1i L, 358 LBS. F-IL P T EL 1987 tCS SEATLE. WA5.NGON 98105 _USA I - I __l A

invaluable. He has a double mission in SHARPY-CYCLE: An Experiment in Pedal life: to record the and to expunge the many myths that are Power and Screw Propulsion by Philip Thiel repeated endlessly in most supposed "histories." What you read here is either true or questioned. There is scope for further work. Meanwhile, you will What do you do if you like boating After further testing this prototype undoubtedly learn much from this but do not care to cope with the whims of "demonstrator" will be available at a unpretentious but valuable book. the wind, suffer the noise and smell of a reasonable price. -Dave Wilson motor, or fuss with oars or paddles? Use Philip Thiel pedal power, of course! 4720 7th Avenue NE AUTERNATE ENERGY TRANSPORTATION Then you may sit comfortably facing Seattle, WA 98105 forward, use your powerful leg muscles USA This typewritten newsletter that to spin an efficient propeller, and have should, presumably, be called "Alterna- your hands free for things more interest- Reviews tive-Energy Transportation", unless it is ing than or paddling. (continued from page 17) designed to complement one of those The Sharpy-Cycle is one of a series of schemes in which motorists are allowed boats exploring these possibilities. This to use their cars every other day, is pub- experimental model is a narrow version to a Draisienne brought to them for repair lished monthly by Campbell Publishing of the traditional "sharpy" hull form and in 1861, when Ernest was 19 (although in New York, NY. It is subtitled "The is lightly and cheaply built of exterior ply- one version puts the date at 1855, when newsletter of technology in motion. wood and cedar, with fiberglas-covered Ernest would have been 13). Ernest later Incorporating chopper noise." I cannot styrofoam sponsons on the sides for invented and built a steam tractor. Of his help you decipher this. But once beyond added stability. A tunnel and well are other sons, Edmond was the sales genius, the title and subtitle you can find interest- built into the hull so that the propeller Henry the promoter and manager, and ing pieces about HPVs, inter alia. It's true and shaft may be retracted for ease in Francisque was another fine engineer and that Daedalus, for instance, is referred to beaching and trailering. The drive system teacher. But the book also taught me as a "flying moped," which seems to indi- uses stock bevel gears, pillow blocks, much about France of those days. For cate further confusion by the headline shaft seal and universal coupling to turn instance, it seems that engineers and writer. The Sunraycer and the Tour de Sol an aluminum propeller. The outboard technicians were forced to relocate are covered extensively and an IIPV News swing-up rudder is controlled by a yoke frequently as the economy changed and comment on the inclusion of hybrid with lines carried forward to the businesses sprang up and went under, vehicles in our fold is quoted well. operating position. just as today. Derek Roberts' footnotes are -Dave Wilson 18 Human Power 7/2 HUMAN POE INDEX 1977-1988 British speed championships 1/5/80/6 This is a first cut at an index of British speed-record attempt 1/6/81/10 all the major articles and many of the Brummer Tim - wind-tunnel tests 1/4/80/7 topics in all the 22 issues of HUMAN POWER Builder s workshop, HPV 3/4/85/1 produced up to August 1988. The four Builders' workshop, second, 5/1/85/7 numbers after each entry refer to the Building of HPVs - Terry Hreno 3/4/85/5 volume/no/year/page. The first issue was Building BPVs - Mike Eliasohn 4/4/85/8 vol.1 no. 1 Winter 1977/8 -I have used the Burrows report from Britain 5/1/85/6 year in which the winter started in all cases. The next five issues have no Cafe Racer, European HPV 6/2/87/7 volume nor number, and I've designated Carson Speed Challenge - ChamplirI 2/2/83/9 them as volume 1, nos. 2-6. A further Clarke, Arthur C. E3/3/87/19 complication is that no. 2 was "Winter 79" College courses in HPVs 1/3/79/7 but came out before no. 3, "Summer 79" - Commuting HPV, design criteria 7/1/88/1 so for conformity I've re-designated no.2 Composites and advanced matls. 1/6/81/4 as "Winter 78". Likewise no. 5, "Winter Composites, cont. 2/1/82/8 81", which came out before no. 6, "Fall Computing across America - rev. 7/1/88/11 81", I have redesignated 1/5/80. There is Covering spoked wheels - Agler 4/4/85/4 only one issue for vol. 4, and that is no. Cyclecars in Sussex - Desmond I 2/1/82/6 4. After that the numbering system is, I hope, logical. To keep entries to one Daedalus triumphs! 7/1/88/2 line I've put in the author's name only if Daedalus project 3/1/85/1 0 there is room. Only the number of the Daedalus HPA rollout I 6/3/87/1 first page of a multipage article is Daedalus - photos and diagram /1/88/19 given. Danta, Randy, HPB design 1/1/77/8 Datsun-Compton Grand Prix 1/6/81/14 Paul Van Valkenburgh edited the first Design considerations for HPVs 4/4/85/1 five issues, with Dick Hargrave as co- Developing countries HP 3/3/85/18 editor for layout and art work. Dick Directors, Board of, 1977 1/1/77/11 Hargrave was editor-in-chief of issues 6- Dorycycle - Philip Thiel 3/2/84/4 8, with Tom Milkie as technical editor in Drag due to internal flow 1/4/80/1 6 & 7, and Dave Swertsen, Stuart Huston Dragonfly II - Steve Ball 1/4/80/2 and Chuck Champlin as co-editors in issues Dutch HPV competition 3/1/84/10 6, 7, & 8 respectively. I took over as Dynamic stability of bicycles 3/1/87/15 editor with the ninth issue, 3/1/84, with help from many dedicated people. Mike Early HP blimps !3/4/86/13 Eliasohn edited all or most of 4/4/85 and Easy Racer history - Martin 2/2/83/7 6/4/87, the HPV source directories. Easy Racer wins Du Pont Prize 5/2/86/6 Eighth IHPSC report - Champlin 2/2/83/1 Let me have suggestions for improving Electric vehicles 1/6/81/2 the next publication of the index. Evolution of new species 5/3/86/10

Fairing - Breeze-Cheater, devt. 7/1/88/4 Dave Wilson Fifth IHPSC - records & reports 1/3/79/1 Figure-eight drive - Patroni 5/4/86/20 Flying Fish breaks record 5/3/86/1 Flying Fish hydrofoil - Brooks 3/2/84/1 Abbott $2500 55-mph prize 1/1/77/2 Foil propulsion at sea - Jakobsen 5/3/86/7 Abbott Prize - reflections 1/3/79/1 Foil-propelled - Gongwer 5/3/86/6 Aerodynamic bicycle fairing 6/2/87/6 Foiled Again - David Owers HPB 3/1/85/1/85/16 Aero drag, std & recmbnt bicycles 3/4/85/3 Fork angle - Mike Eliasohn 4/4/85/3 Aeroshell fairing results 1/4/80/7 Free-blown canopies - Tom Milkie 2/2/83/12 Aeroshell, Team 1/1/77/6 Friction damping as shimmy cure 7/1/88/6 Airship White Dwarf 3/3/85/1 Angular momentum and stability 6/3/87/4 Goals, rules and innovation 6/2/87/1 Arm-leg cranking systems 6/3/87/8 Gossamer Albatross 1/2//78/2 Arm-powered machines 1/2//78/2 Gossamer Condor 1/1/77/4 Arms race - new world record 3/1/84/8 Automatic transmission, Reswick 5/4/86/16 Hale tricycles (letter) 5/4/86/3 Auxiliary HP in sailboat race 3/2/84/13 Helfrich, Gary, master builder 3/3/85/9 Helicopter Sikorsky competition 5/2/86/16 Backward vs forward pedalling 6/3/87/1 Helicopter HPA update - Tobias 5/4/86/2 Backward pedalling - comments 7/1/88/8 Helicopters - Japanese work 6/1/87/3 Baidarka, review 7/1/80/11 History of rowing 3/2/84/2 Bicycle research - symposium 5/1/85/2 History, IHPVA 1/1/77/10 Bioenergetics, arm-leg cranking 6/3/87/8 Homeless HPVs - Dennis Dollens 7/1/88/10 Bionic Bat - Lynn Tobias 3/1/84/3 HP floats - Alex Brooks 2/2/83/13 Blimps and HP flight - Allen 3/3/85/4 HP foot in the door - Peter Ernst 6/2/87/4 Bluebell's victory 2/2/83/6 HP in developing countries 3/3/85/18

7/2 Human Power 19 HP seacraft: Bill Watson 1/1/77/9 Practical HPV competition 2/1/82/2 HPA Light Eagle test flights 5/4/86/1 Pressodyne II - Alec Brooks 1/4/80/3 HPA optimization - Schoberl 6/1/87/4 Prize donors - salute to 3/1/84/14 HPA, inflatable Phoenix 3/4/85/17 Propeller for HPB 3/2/87/10 HPB design: Randy Danta 1/1/77/8 Propellers for HPVs - Larrabee 3/2/84/10 HPB regatta - IHPVA first 3/1/84/7 Public-relations report 1/3/79/6 HPBs - comparative speeds 5/1/85/2 Publicity on HPVs 1/1/77/7 HPBs - report on Vancouver 5/3/86/1 i HPBs - "Getting wet" 1/3/79/6 Ready About, review 5/4/86/14 HPV builder's workshop 3/4/85/1 Records '77 1/1/77/16 Human factors of long HPA flights 5/4/86/8 Recumbents on dirt roads 5/2/86/13 Hybrid vehicles and HP - Schmidt 5/2/86/4 Riblets for turbulent-drag redn. 5/2/86/3 Hydro Challenge (HPBs) 2/1/82/2 for Bangladesh 4/85/27 Hydrofoil, HP, development 3/3/85/11 in Bangladesh- Willkie 5/3/86/19 Hydrofoil breaks 2000-m record 5/3/86/1 Rickshaws in Bangladesh, pt II 5/4/86/5 Rightmyer's monocoque triple 1/5/80/3 Icarus, The Boat that Flies 7/1/88/18 Road race, IHPSC '78 I 1/1/77/9 IHPSC, 7th, photos & comments 1/6/81/6 Rolling drag - three vs two 5/1 /85/1 2 IHPSC, 8th, plans 2/1/82/2 Rose, Sid, of Capetown 1/2//78/8 IHPSC highlights 1980, (photos) 1/5/80/4 Rowing - theoretical study 3/2/84/3 IHPSC: British view 1/6/81/1 Rowing machine, Flexifit Ltd. 7/1/88/1 5 IHPVA history 1/1/77/10 IHPVA first boat regatta 3/1/84/7 S.Africa HPV racing (letter) 2/2/83/2 IIHPVA around the world 1/2//78/7 Safety research 3/1/84/23 Indy photos (1984) 3/1/84/11 Scientific Symposium - second 3/1 /84/18 Innovators challenge bike racers 1/3/79/7 Scientific symposium, first 1/6/81/2 IPSOB 1/6/81/3 Scientific Symp., 1st, review 2/1/82/5 Sea Saber and other HPBs - Knapp 3/2/84/12 Japanese IHPVA competition 1/2/78/7 Shimmy cured by friction damping 7/1 /88/6 Joyrider pedalling mechanism 3/4/85/14 Sidewheeler HPB - Phillip Bolger 3/2/84/10 Solar: human power? Peter Ernst 5/1/85/1 Kremer prize claimed by MIT 3/1/84/1 Source guide, builders', second 6/4/87/1 Kremer World Speed competition 3/1/84/3 Source directory, first 4/4/85/2 Source-guide update 5/3/86/13 Laminar-flow underwater vehicles 2/2/83/16 Speed-sailing week - report 7/1/88/3 Leitra tricycle - Rasmussen 5/1/85/14 Spoked-wheel response 5/2/86/12 Life with an HPV builder 2/2/83/14 Stability, dynamic, bicycle /1 /87/1 5 Lightning X-2 development 3/1/84/21 Stability of bicycles & momentum 6/3/87/4 Linear pedalling 1/4/80/3 Steering geometry note 5/1/85/13 Submarine, HP competition 6/3/87/3 MacCready, Paul: goals and rules 6/2/87/1 Submarine, HP, O'Neil dry HPS 7/1/88/17 MacCready, Paul: Gossamer Condor 1/1/77/4 Submerged-buoyancy HPB - Schmidt 3/3/85/6 Machine technology 1/2//78/4 Swinging-arc pedalling 3/4/85/14 Madeline - pedalled sidewheeler 3/2/84/10 Major Taylor - champion 6/2/87/20 Tandem recumbent - Kurt Wold 6/3/87/3 Mallard HPB, sea test 5/4/86/14 Ten-speed fairings 3/1/84/23 Material selection - Bartter 4/4/85/4 Therrio, Ralph: Aeroshell 1/1/77/6 [le,,,ber's forum (letters &c) 2/1/82/3 Traction on ice, how to get 5/4/86/1 3 Michelob Light Eagle test flights 5/4/86/1 Trailer, construction of Flunder 6/1/87/20I MIT Monarch B: Kremer winner 3/3/85/21 Transmission, automatic, Reswick 5/4/86/15 Monarch wins third Kremer prize 3/1/84/1 Travelling with the Vector 2/2/83/14 Musculair 2 HPA 5/1/85/11 Tricycle steering geometry 4/4/85/5 Musculair 1 & 2 HPAs - Schoberl 5/2/86/1 Tricycles, long and short WB 4/4/85/3 Triflex speed vehicle - Gentes 1/4/80/4 Oar and rigger experiments 3/3/85/3 Tube-frame recumbent suggested 4/4/85/7 Officers, IHPVA, 1977 1/1/77/11 Twenty-knot HPB - Alec Brooks 6/1/87/1 Oh for the wings - Clarke 6/3/87/19 Two wheels vs three wheels 4/4/85/1 Olympics bicycle-design project 2/1/82/11 Olympics project update - Kyle 2/2/83/1 Van Valkenburgh, story of record 1/1/77/6 Oscillating-foil propulsion 5/4/86/7 Vector record run on freeway 1/5/80/1 Overseas HPV competitions 3/1/84/10 Vectorl World's fastest HPV 1/3/79/4 Oxygen cost: recumbent vs convnl 6/3/87/7 Ventilation of faired HPVs 6/2/87/5 Oxygen cost, pedalling - comments 7/1/88/9 Water Strider HPBs - Richard Ott 3/2/84/1 5 Partially faired HPVs - Hreno 3/1/84/15 Waterbug HPB 3/4/85/10 Paul Van Valkenburgh 1/4/80/7 Watson, Bill: HP seacraft 1/1/77/9 Pedal height and crosswinds 5/2/86/3 White Lightning - wind-tunnel 1/4/80/6 Phoenix inflatable HPA 3/4/85/17 White Dwarf HP Airship 3/3/85/1 Photograph album of HPVs 1/1/77/12 Who needs a wind tunnel? - White 1/5/80/7 Practical HPVs at last - Abbott 2/2/83/8 Winter tricycle - Fred Willkie 3/4/85/11

20 Human Power 7/2