Human PowerThe technical journal of the

International Human-Powered VehicleAssociation

David Gordon Wilson, editor21 Winthrop Street

Winchester, MA 01890-2851, USAPhones: 617-729-2203 (home)

617-253-5121 (MIT)617-258-6149 (FAX)

dgwilson¢.mit.edu (email)Associate editors

Toshio Kataoka, Japan1-7-2-818 Hiranomiya-Machi

Hirano-ku, Osaka-shi, Japan 547Theodor Schmidt, Europe

Hoheweg 23CH-3626 Hunibach, Switzerland

Philip Thiel, watercraft4720 7th Avenue, NE

Seattle, WA 98105, USAIHPVA

P.O. Box 51255Indianapolis, IN 46251, USAPhone & FAX: 317-876-9478

OficersMarti Daily. president and

executive directorAdam Englund, secretaryTess Machlin, treasurer

Paul MacCready, int'l president(Vacant), VP water

Stephen Delaire, VP landChris Roper, VP air

Matteo Martignoni, VP ATVTheodor Schmidt, VP hybrid power

Board membersAllan Abbott

Leonard BnmkallaMarti DailyBill GainesGaylord Hill

Chet KyleAndrew LettonGardner MartinDennis Taves

Hunan Power is published near-quarterly by the International Human-Powered Vehicle Assoc., Inc., a non-profit organization devoted to the studyand application of human muscular po-tential to propel craft through the air, inand on the water and on land. Mem-bership information is available bysending a self-addressed stampedbusiness-sized envelope to the IHPVAaddress above.

Additional copies of Human Powermay be purchased by members for$3.50 each, and by non-members for$5.00 each.

Material in Human Power is copy-righted by the IHPVA. Unless copy-righted also by the author(s), completearticles or representative excerpts maybe published elsewhere if full credit tothe author(s) and the IHPVA is promi-nently given.

We are indebted to the authors, toMarti Daily and to Maggie Beucler,whose dedicated help made this issuepossible. Dave Wilson

In this issue

COGITO-II AND THEDREAM-SHIP RACES

Any thought that the US or Europestill represents the center of the humnan-power movement has to be dispelled bythe first paragraph of the account in thelead article in this issue of the winningof the 1993 "Dream-Ship" race in To-kyo. There were 30,000 spectators rightthere, and countless more on TV! (Asimilar number view the Japan Interna-tional Birdman Competition, for glidersand hunan-powered aircraft). TsuideYanagilhara and his co-authors discussthe design decisions they made to winthe 200-m standing-start race againstvery strong competition, and comparethese decisions with those made by AlecBrooks and Allan Abbott for the FlyingFish. This article is bound to be re-quired reading for all future builders ofhwnan-powered hydrofoils.

FIN POWER AND THETHISTLE

Harold Bryan, a boat builder fromNew Brunswick, shares with us his studyof the swimming actions of fishes andhis application of those actions tohuman-powered boats. He relates hiswork to that of three predecessors whohave reported their fin-propulsion pro-jects in these pages, and gives details ofsome of his designs. He will undoubt-edly inspire others to follow.

BUILDING ALUMINUMRECUMBENTS

Mike EliasolLn continues his seriesof wide-ranging surveys of technologicaldirections with this collection of inter-views, photographs and useful construc-tion details. As with his other reports,Mike gives a balanced view and leavesthe reader to decide. There are advan-tages and disadvantages to the use ofaluminum (alloys) for recumbents, but,as one might expect, the builders don'taltogether agree.

THE AERODYNAMICADVANTAGE

In "the unfair advantage?" MartinStaubach reports careful measurementsof aerodynamic drag on a variety of bi-cycles, recumbent and otherwise, andtwo tricycles. He arrives at resultswhich may be surprising to N. Americanreaders, accustomed to having speed

records fall to long-wheelbase machines.He points out that in Europe the short-wheelbase recumbent bicycle is king.Read and learn - and write to HP withyour reactions!

A NEW INDEXYour editor has rallied to produce

the second index of his now-ten-yearreign. In order to do so, the early issuesof Human Power, which were producedon a rather random schedule and withinconsistent or no volume or issue num-bers. have been labeled in as logical amanner as seems possible. This includesa previously overlooked early issueomitted from the last index and broughtto our collective attention by a diligentreader. May more of equal persistencefind areas where the present index couldbe improved. All it contains at presentis a double entry for each article andeach note or letter considered to be ofspecial significance: one entry for thetitle or topic and one for the first author.It would be useful to have entries for allsub-topics within the articles, but theindex would thereby become rathercumbersome. However, if there is astrong call for this to be done and volun-teers willing to do it we would publishit.

A NEW FORMAT FOR HPWith this issue I'm trying a new ar-

rangement. I often feel irritated whenreading a newspaper at stories that starton page one and are continued on p. 34.I noticed that the journal SCIENCE sel-dom does that. With the last revision ofits format, that publication also startedsummarizing its principal articles, and Iliked that too. So you'll find my sumn-maries of the main papers and articlesright here on this page. And all of theseprincipal articles will start on a newpage and will continue on to the follow-ing pages until they end. The last pageswill be filled up by reviews, letters andshort items. Something has to be dis-jointed - we don't have advertisements tofill up pages as do many publications -and it seemed better that the letters andso forth be somewhat scattered than thearticles themselves. The editorials alsoget relegated to a later position in thejournal. Editorials are simply rewards toan otherwise uncompensated editor toallow her/him to sound off and feel moreimportant in a "bully pulpit", and couldwell go last. Let me know if you likethe new arrangement or hate it.

Dave Wilson

p. 2 Human Power, winter-spring 1993-94, vol. 1111

weldable alloy. Each A6061 tube wasinserted in the lug sleeve and was fas-tened by several blind rivets to form atruss-frame component.

The main foil (figure 4) was made ofpre-preg carbon fiber laminated in a pair(upper and lower) of female molds. Asthe foil is of cantilever construction, car-bon fiber was the only choice to assurenecessary strength and lightness. Thefoil spar is made of uni-directional car-bon fiber, and the shell is of two-ply pre-preg 45-degree-bias carbon/acrylicfoam/carbon sandwich construction tohave sufficient torsional stiffness. Thecanard and its strut are of solid carbonfiber.

The main strut (fig. 7) was made ofthree parts: an H-shaped spar was madeof aluminum (A7075) by machining, theleading and trailing edges are of shavedspruce, and the shell is of solid carbonbias laminate. Those parts are bondedby epoxy glue. The weight-strength ra-tio of spruce is as good as that of steel,and also its wide adhesion area was fa-vorable for this application.

The pontoon hulls are made ofA2024 aluminum-alloy sheet, 0.5 mmthick, and the decks of carbon-fiber pre-preg sheets (figure 8). To minimize the

building time and cost, the half-roundsections of the pontoons were formed bysimply hand- bending the aluminumsheets, thus eliminated the use of anylamination molds. Before the construc-tion, a one-twentieth-scale model wasmade to simulate the actual constructionprocess. Consequently the pontoonswere made in one day.

The propellers are made of alumi-num round bars. The boss was turned ona lathe and the blades were milled, thenwelded together.

DREAM-SHIP RACE - NEXTYEAR

Since the race rules are fairly simple(overall length less than 5m, beam lessthan 2.5m, and the crew two personsmaximum.) and as this race is open toanybody who lives in Japan, more than200 boats participated in the local elimi-nation races this year. The final event inTokyo (three-step elimination) wasraced by 28 boats which survived thelocal eliminations and two seeded boatswhich were the last year's champion andthe third (last year's second team didn'tshow up this year).

From this year on, a separate "stu-dents class" was made to give themchance to be honoured among "profes-sional" shipbuilding-company teamssuch as Mitsubishi Heavy Industry, Mit-sui Engineering and Shipbuilding, HI,NKK etc. A total of six student teamssurvived the local eliminations.

The authors' team "COGITO", withonly a handful of members, won the fi-nal race by beating the teams from thosebig companies. The reason which mem-bers believe is that they could integratespecialists in small-boat design and ad-vanced composite technology, and theycould employ master craftsmanship andexpert riders.

In next year's race, the winning timewill be definitely shorter than 30 sec-onds, and the "COGITO-II" design willbecome obsolete. The race will becomemore governed by athletic prowess thandesign skills because the performancelevel of the boat design itself may beoverwhelmed under the currentregulations.

Tsuide Yanagihara, 734-153 Okubo,Iwata-shi, Shizuoka-ken, 438 Japan

All the authors are colleagues at Ya-maha Motor Company. Tsuide is a boat

designer with an aeronautical-engineering background and a hobby ofsoaring. Tokuzo Fukamachi is a navalarchitect and amateur boat-builder.Takashi Motoyama is a specialist in ad-vanced composites and is a holidaysailor. Toshio Kataoka, HP's associateeditor, Japan, requested and transmittedthis paper: ie wrote of the authors:"Having been stimulated by the IHIYVAevents in the U.S., the), decided to buildtheir own boat to compete in the DL)ream-Ship competition. COGITO-H is a prod-uct of their individual skills and knowl-edge. They express their gratitude to thepoMterful riders Shunsuke Horiuchi,Masaki Kamimura and Disuke (C'hiba.And the editor is most gratfidl to all!

REVIEWRecumbent Cyclist NewsWith the latest issue, no. 18,

January/February 1994 RCN is beingfully computer generated. It occupies aniche that is separate and different fromour HPV News and Human Power. It isalmost completely a consumer's maga-zine, reporting on manufacturers' devel-opments and testing their products. Inthis issue there is an article comparingthe Counterpoint Presto with the EasyRacer, for instance, by Ollie Deex. Gen-erally the reviews avoid being outrightcritical of products, but usually one canread between the lines. Our own Mi-chael Eliasohn, like the editor Bob Bry-ant a newspaper reporter, writes areview of the 1993 IHPSC. There is aphoto and a discussion of the Cannon-dale recumbent with several contribu-tors. Everyone believes that ifCannondale decides to take the plungeinto recumnbents, others will follow.Rick Pope reports on Interbike Las Ve-gas '93, and there is a home-builders'section. There are also a lot of adver-tisements by recumnbent builders andothers.

RCN is being mentioned increas-ingly as a source for buyer informationwhen the popular press covers an HPVevent, and, while we may wish that ourIHPVA Source Guide would be regardedas the "bible", we must acknowledgethat Bob Bryant and RCN are winningmany converts to recumbent bicycling.A one-year U.S. subscription is $25.00:RCN P.O. Box 58755, Renton, WA98058-1755

Dave Wilson

Human Power, winter-spring 1993-94, vol. 11/1, p.5

Figure 7 Main-strut cross-section

DECK:CARBON COMPOSITE/ PI Y+4 -Flg)

0\DECK FLANGEWOOD

A2024-T3TO.5MM

Figure 8 Section of pontoon hulls

l

I

11_1

SUMMARY

The fin-powered concept describedhere was developed with almost noknowledge of other experiments withpedal-powered craft. My only modelwas the paddle-wheel boats that can berented at vacation beaches and that showvast room for improvement. The drivesystem and boat we now build were con-ceived on a sailing voyage where time tothink was the greatest gift.

The major inputs to the design proc-ess were: 1. fish caught and studied, 2.close observation of swimming fish ataquariums in Auckland, N.Z. and Mon-terey, California, and 3. the book HowAnimals Move which I studied at thepublic library in Honolulu, Hawaii. Un-fortunately, I neglected to copy downthe author and publisher of this work.When problems developed in the designprocess, solutions were usually found byreturning to a study of fish anatomy.

Speed through the water has beenimportant only if it contributes to effi-ciency at cruising speed. Reliability,relaxation, and ease of pedaling havebeen the guidelines.

PREVIOUS H.P. FIN BOATSEarly in the evolution of this design

we used whales and dolphins (with theirhorizontal tails) as models. Einar Jakob-sen has worked with this concept (Hu-man Power vol. 5, no. 3 Fall 1986) ashas Trond Oritsland (letters to the editorH.P. vol. 9, no. 2 1991). A horizontal-foil boat was built by Parker MacCready(H.P. vol. 5 no.3). Although this ap-proach has proven to have potential, sev-eral problems exist which cease to existor are easier to compensate for with thevertical fin which we have chosen.

ADVANTAGES OFVERTICAL FINS

For the horizontal fin, the center ofoscillation must be at least half the dis-tance the fin will sweep below the wa-ter's surface if the fin is to remainsubmerged. This means that some of thedrive mechanism must be at this depth.

This makes it susceptible to damage.Also, this drive mechanism (any under-water part which is not the fin) will con-tribute to drag.

OPTIMUM STROKEWe have found also that with a dis-

placement hull (canoe or kayak form)there is a greater efficiency in a sloweroscillation of the fin sweeping a largearea than in a shorter and quicker stroke.This motion seems best at 1:1 with thepedal stroke which greatly simplifies thedrive system. A large swept area meansgreater depth of stroke with the horizon-tal fin which we see as limiting the areathe boat can be used in. Our fin willkick up as does a small sailboat rudderwhen it encounters an obstacle or

shallow water. It will swim over a shoalor through a patch of seaweed.

One other great advantage to the sin-gle vertical fin is that steering as well aspropulsion is achieved with no addi-tional mechanism. Once this last advan-tage was seen, we concentratedcompletely on the vertical fin.

DOUBLE VERSUSSINGLE FINS

Calvin Gongwer has experimentedwith double vertical fins (also H.P. vol.5 no. 3). This may reduce the fin-induced rolling if the fins oppose eachother, but steering would then be muchmore complicated. I will return to steer-ing below.

USE OF FLEXIBLE FINThe fin we use is quite flexible as we

have made a conscious effort to matchthe characteristics of a fish. There ap-pear to be definite advantages to this

p. 6 Human Power, winter-spring 1993-94, vol. 11/1

FIN POWER - SUCCESS COMESFROM COPYING NATURE

byHarry Bryan

1. Start of stroke by rightfoot pressure.Spring is fully extendedageinst its stop.Fin/arm Joint is at maximumangle.

2. End of the right stroke.Note that fin is still prov-iding forward thrust.

3. Shifting to start the leftfoot stroke. The spring is Justbeginning to be re-tensionedafter the fin swings past center.The fin is releasing Its storedenergy.

Rope -r P!ALS)I'iglure I iStvXoke-dlriiye diagramls

_ . . . . _

---- .

-----------

r

FiNA-1--

I ,I

over a rigid foil. As the fin swings tothe side it bends and twists in reaction towater pressure. The more it can bend,the longer the stroke can be and still pro-duce forward motion. The best con-struction seems to have a narrow butstiff leading edge and a quick change tothe main area of the fin which is quiteflexible. This is similar to a fish.

Even with a flexible fin, you cannotswing past about 30 degrees from thecenterline of the boat and still maintain afavorable angle of attack. A more flexi-ble fin would allow this, but when thefin is too flexible sufficient power can-not be transmitted to the water. We canincrease the length of the arm to sweep alar{er area with the ame 30 devres but

this gets clumsy and begins to make theboat look odd.

USE OF A FISH JOINTOur solution to delivering more

power without increasing fin area or armlength was to (once again) copy the fish.Just in front of the actual fish's fins westudied is a joint that is controlled bymuscles and has a limit of bend at about25 degrees from the centerline. We in-troduced this joint between the

oscillating arm and the fin at its end,added a muscle in the form of a spring(which tries to keep the fin in line withthe arm) and a stop in the form of a ny-lon cord within the spring which limitsthe joint to a 25-degree deflection.

Because the fin is now allowed topivot 25 degrees as well as flex, the armcan be oscillated back and forth about 45degrees and still provide thrust at its ex-tremes. The spring performs three func-tions. First it makes smooth transitionfrom the end of one stroke to the begin-ning of the next. Without the spring,part of the pedal stroke is lost as the finshifts from stop to stop. The spring andthe flex of the fin material both store.energy which is released at this other-wise inefficient part of the stroke-cycle.The second function of the spring is toallow for light shallow strokes. If therewere no spring and the arm were oscil-lated less than 25 degrees from center,the fin would just swing on its pivot andprovide no thrust. The third contributionof the spring is to hold the fin far to oneside if a tight turn is being made.

SPRING TENSIONThe correct spring tension seems to

be that which allows a cushioning effectas the spring is extended against its stopduring moderate pedaling. Light tensionis good for light pedaling but feelssloppy in a sprint. Heavy tension allowsgreater speed but is inefficient at slowand moderate pedaling. Our present"cruising" spring is 75 mm at rest and150 mm extended. At this length thetension is 58N (13 bf.).

FIN SHAPESSix fin shapes have been tried so far.

All have been able to push the boat athull speed (about 2.2m/s, 5 m.p.h.). Theimprovements have been in reaching thisspeed with less effort, and in designingto eliminate stress points and consequentmaterial failure.

The leading edge of the fin, whichengages the cheeks at the pivot, extendsnearly the whole distance to its tip. It iscut from two pieces of General ElectricLexan polycarbonate plastic. These areeach 6 mm thick. Sandwiched betweenthese is a single piece of 1.5 mm (1/6")Lexan forming the bulk of the fin. Earlystructural failure was partially attributedto the effect of the solvent glue (methyl-ene chloride) used to bond the piecestogether. Present practice is to use 3M5200 polyurethane adhesive backed upby copper rivets.

Given a fixed area of fin needed toload the leg muscles efficiently, thechoice of fin shapes goes from narrowand vertical to a shallow shape extend-ing aft. The fish equivalent is from tunato trout. The deep narrow blade will re-quire a stiff leading edge. We use hard-wood on the edge of this style of bladebecause it is stiffer than Lexan. It is thefastest shape. Its drawback is 150 mm(6") more draft (160 mm (24") ratherthan the average 450 mm (18"). Also, asmentioned, there is a bit more rollingwith a deep fin.

As the fin design angles back moreand more, its leading edge must becomemore flexible in order to provide for-ward thrust at the end of each stroke.Spring tension must also increase tocounteract the leverage of the fin area asit moves aft of the pivot. The two finshapes illustrated represent what wehave found to be the practical limitsgiven the present fin-drive mechanismand fin material.

Human Power, winter-spring 1993-94, vol. 11/1, p.7

Ii,I

Figure 2 Fin consttruction details--

PROTOTYPE HULLThe hull of the prototype, "Thistle",

was designed to meet the needs iand po-tential of the drive system. Its length is4m (12'6"). Beam is 750 mm (30").Two fixed fins are fastened to the hull.They correspond to the anal and pelvicfins of a fish. The anal or further aft finopposes the tendency of the fin action tomake the boat roll. More importantly itkeeps the stern from wiggling due to thesideways force generated by the fin.The forward fin aids greatly in maneu-vering. It gives a point to turn aroundwhen steering and keeps the bow fromblowing away when the wind is on thebeam.

C C')

eJ-AL

il~:a~

Figure 4 Two alternative pedal typ)es.

PEDALS AND ROPESLow-stretch-polyester ropes transmit

pedal motion to the fin-drive mechanismthrough plastic tubing built into the hull.The pedals are reciprocating (rather thanrotary). They pivot on bearings fastenedto the inside bottom of the cockpit.

Steering is achieved by either coast-ing with one foot depressed or pedalingwith the fin to one side or the other.

This boat has proved to be easy topedal for long distances and extremelyeasy to learn to steer. The feeling ofcontrol (both propulsion and steering),being all in the legs, gives the naturalfeeling of walking to water travel whilefreeing the hands for photography, bin-oculars, or fishing.

"Thistle" was designed to match thethrust miand steering characteristics of thefin drive uwit with a suitable htull form.She is small enough to be modestly lightin weight and easy to carry on top of acar. Her layout allows for the semi-recmunbent position best for pedaling,stability, and windage. The hatches ateither end provide storage and flotation.

N Z r

The drive unit itself has changed lit-tle at all since its building. To mimic itsmotion, wave you ann from side to sidein a slow, horizontal handshake. Letyour hand be like a fish's tail. Thus, thepintle joint becomes the elbow joint, thesecond pivot just in front of the fin be-comes the wrist joint. The solid piecebetween these hinge points is the for

arm. The tilt-up "rudder" cheeks and thefin itself are referred to as the fin.

Look at the drawing of the boat fromabove. Imagine pressure applied by theright foot. The drive rope (which passesthrough a polyethylene tube from thecockpit then out through the hull nearthe stem) pulls the forearm to starboard.The fin does not want to be moved side-ways, so there is a twisting at the wristjoint. This causes the arm extendingforward from the fin cheeks to move offcentre, which movement is resisted bythe spring colmected from this forwardfin arm to the elbow-joint pin. Theharder you push on the pedal, the moredeflection there is until a doubled nylonstarter-cord stop inside the spring comestaut. This stop is at approximately 25degrees. A fish's tail (a dorado's at anyrate) seems to come tip solid at the samepoint.

The fin itself is now in the best posi-tion to impart forward motion, miand itnow moves to starboard following theforearm. The flexible parts of the finbend which makes a more efficientshape. This bending also stores energy.

At the end of the stroke, the energyin the flexed fin is released while the leftfoot causes the forearm to start back toport. Without the spring, this motionreversal is sloppy. Also, the springmakes light, shallow pedal strokes possi-ble where the stop angle is not reached.Steering is crude without the spring aswell.

Spring tension with the fin shapesillustrated seems best between 10 and 20lbf measured with the spring extended toits stopped length.

The unit will go through heavy weedor over floating rope without fouling.

I believe this concept will be at itsbest for fishing, bird-watching, photog-raphy, or just as a pleasant way to getsome exercise. It is a complicated oarbut a very simple outboard motor.

FIN-DRIVE DETAILS1. Forearm- 3/4" oak with 1/8"x 1"stainless steel screwed to the top andbottom. Bearings made from drilled-out1/2" s.s. rod are welded to the front ofthe flat stainless while the other end isdrilled for the 1/4" wrist bolt.2. 1/8"x 1" stainless steel,3. Spring and nylon stop. Collapsedlength is 5". Extended length is thatwhich allows an angle of 20 to 30 de-grees between fin and forearm. Spring

p. 8 Human Power, winter-spring 1993-94, vol. 11/1

Figure 3 "Thistle" hull shaIe.

_

___,J I T_- �

6xzs Ls u , Tii

If you compare SWB- and LWB-recumbents it is apparent why theEuropean racing scene is dominated bythe short versions. The LWB bikes (5)are ahead of the standard racing bikeonly in terms of comfort and safety (2and 3 ). Only the SWB-recunbents (7and 10) have real advantages.

To prove the effect of variousequipment I measured various posi-tions and fairings on the same SWB-recumnbent. If you lay one arm onyour body on a bike with low handlebars, CdA is reduced by 9% (8). Ifyou mount a high handle bar, botharms are taken out of the wind and thegain doubles to 20% (10). Cause ofthis effect is the reduction of the fron-tal area A. A simple aerodynamnicallyshaped bag made of fabric and stand-ing on the rear carrier reduces the Cdcoefficient by 20% (9). High handlebars and the aero-bag together didn'tgive an advantage in this case, becausethe bag was wider than my body andcounterbalanced the effect of the higharms (II11).

As expected a full fairing is the bestmeans to cheat the wind. TheCANARD-fairing reduces the vehicledrag-area of a SWB-recumnbent to al-most one third (CdA = 0.13 m2) (13).With a frontal area of about 0.52 m2

the resulting Cd-coefficient is 0.25.This is comparable to those of goodcars. It is not better, because the headand parts of the vehicle are unfaired.The Danish LEITRA has a faired fore-body, but unfaired front wheels. ItsCdA is 0.24 m2 (15), which is quitesurprising for a fully faired vehicle.This is a figure that can almost bereached by an unfaired racing SWB-recumbent. But these vehicles can't besimply compared. The LEITRA is notdesigned for aerodynamics but first forweather protection and nimbleness onnarrow roads.

COMMENTThe figures show that the streamlin-

ing efforts of the 80s have made stan-dard bikes quite good. But unlike therecumbents the development of theracing bike (meeting the UCI rules)has already reached its peak. This

peak was Mike Burrows' Lotus bike. Ithink this bike can't be improved fur-ther without violating UCI regulations.For recumbents this development hasalready taken place in the thirties,when Francis Faure beat almost every-body with his Velocar recumbent builtby Mochet. The aerodynamics of thisunfaired vehicle was even then betterthan today's best UCI bikes. Onecould think racing-bike developers had50 years to learn from this but in factthey still aren't very creative. Mostquantum leaps were made by tuncon-ventionally thinking people like MikeBurrows. It was a pleasure to see hisgood-idea bike win against the big-money wind-tunnel bike developed bythe German FES in the Olympic Bar-celona track races (even though it's notvery patriotic of me).

We are lucky to work on recun-bents, because we will not be unem-ployed soon. There still are manyimprovements to be made, as the de-velopment of the Z-frame SWB-recunbents show. Unfortunately Ididn't have one of these low-to-the-ground machines for my measure-ments. See, there is still much work tobe done!

Martin Staubach is a 25-year-old stu-dent of mechanical engineering at theOhm Fachhochschule in Nibrnberg.lie lwas the second chairman of theGerman HPV association in 1992. Ashe has been active in the HP V scenesince 1986 he had enough time tobuild some 30 recumbents and Mwin abunch of races. Among the recum-bents wMas the vell-known Z-2 proto-type with full suspension, and Z-2f airing made of Kevlar/fbam/epoxysandwtich. This and the C'ANARD fair-ing, Europe's most stuccessil commer-cial flfl firings, were developed by ateam offive people ftom southern Ger-man1y. At the moment some equipment.such as a carbon fiame. .front.faiiringand seat-ventilation sy steim are in themaking. In 1992 he opened Germnan'sfirst recumbent store together uwith hispartner Bernard Klar. As there aremany ideas and plans to be realized he1wishes to retire at the age of 28 to get

going on1 them. There are even somethings besides bikes in life ...

Martin Staubach, Holzschuher Strasse8, D 90439 Niirnberg, GermanyPhone: 0911-266 343

IN FAVOR OF CARBONFIBRE

[This letter is reprinted, with permis-sion, froml the tt' V Internet mail - Ed

Having ridden a carbon-fibre bikefor a couple of years now, I have todisagree with most of another [Inter-net] correspondent's comment that"carbon fibre doesn't generally buyyou a whole lot". I agree that carbonfibre used as tubes with lugs doesn'tbuy you much. But monocoque con-struction, e.g. Kestrel, enables you todo things that have never been, andprobably could never be, done withsteel or aluninum. And far from be-ing of interest only to racers, I thinkthat the greatest payoff of CF (or anyother advanced material) will be forreal-world riders. Frankly, I've beensurprised and disappointed by thestructural conservatism of HPVbuilders.Basically, my point is that advancedmaterials like CF can reduce structuralweight dramatically, but only a portionof a bike's weight is structural. Thegreater the fraction of a bike's weightthat is structural, the greater the pay-off. Since real-world bikes (especiallyrecumbents and HPVs) have morestructure than racing bikes, using ad-vanced materials will have a biggerpayoff for them. A steel road-racingbike weighs about 24 lbf, made up ofabout 20 lbf of componentry on a 4 lbfframe. If CF cuts structural weight inhalf that would only save 2 lbf.. Asteel LWB recumbent might weigh 10lb. more than that racing bike with thesame components, so CF might save 7lbs instead of 2. And the all-weatherHPV prototype Nick's been ridingweighs about 90 Ibf, say 25 Ibf ofcomponents and 65 lbf of structure (in-cluding cardboard fairing) , so ad-vanced materials could save 30-40 lbf.That's the kind of weight

Human Power, winter-spring 1993-94, vol. 11/1, p.15

__ ___- ~ ~~~~~~~~~~~ --- -___

_

VEHICLE DRAG-AREA(CdA)MEASURED BY COASTING DOWNHILL

NO. VEHICLE DESCRIPTION CdA IMPROVEMENT AGAINST:m2 STANDARD SWB

BIKE RECUMBENT

1 Standard bike, TV 0,60 0 -71

2 Racing bike, RV, halnds on brake levers 0.49 18 -403 Racing bike, RV, dowlnhill racing position 0,42 30 -204 Racing bike, RV, RS, triathlon handle bars 0,24 55 23

5 LWB recumbent, TV, LHB, BBS -200 0,49 18 -406 LWB recumbent, TV, LHB, BBS -150, Front - Zzipper 0,36 40 -3

7 SWB recumbent, TV, LHB, BBS +60 0,35 42 08 SWB recumbent, TV, LHB, BBS +60 one hand on body 0,32 47 99 SWB recumbent, TV, LHB, BBS +60, aerobag 0,29 52 1710 SWB recumbent, TV, HHB, BBS +60 0,28 53 2011 SWB recumnbent, TV, HHB, BBS +60. aerobag 0,29 52 1712 SWB recumbent, RV, RS, HHB, BBS +60 0,25 58 2913 SWB recumbent, CANARD full fairing 0,13 78 63

14 Tricycle KWADRAD II, TV, 2 front wheels,I rear wheel, BBS 0 0,43 28 -23

15 LEITRA tricycle 0,24 60 31

NOTES:All measurement were made in street clothing (jeans, sweater, no jacket), except those withthe designation of RS (racing suit).The height of the test rider was 1,80m.

DesignationsTV Touring version (mudguards, carrier, light)RV Racing version (bike stripped)BBS Bottom-bracket height above seat in mm; negative figures means that BB is wiunder seat.LHB Low handle bars under the seatHHB High handle barsRS Racing suit

Martin Staubach 1993

(C'ontilned. a letter on carbon fibre)

savings that you can feel with everypedal stroke. And the kind of weightsavings that can make the differencebetween a viable product and adinosaur.Dave Van Horn 9236 NE 13 6th P1Kirkland, WA 98034, USA(e-mail davevhg(microsoft.com)

p.16 Human Power, winter-spring 1993-94, vol. 11/11

LETTERS TO THEEDITOR

ADDENDUM TO "ACONTROVERSIAL ISSUE:HUMAN-ENERGY ACCU-MULATORS FOR HPVs

by Peter A. Sharp

The "one-minute rule" I proposedin HP vol. 10 no. 3 p. 19, which wouldallow competitors to accumulate en-ergy for one minute before the start ofmost of the International Human-Powered Speed-Championship(IHPSC) events, requires an addition.If left exactly as proposed, the rulemight encourage some competitors toabuse the rule. The problem is thatcompetitors could use a particularstrategy that would enable them to ac-cumulate energy for more than the le-gal one minute, in both the drag-raceand the top-speed events. Fortunately,this problem can be easily resolvedwithout causing any complexities orinconveniences for the competitors.

The problematic strategy wouldbe this: a competitor in the drag racecould remain at the starting line afterthe starting signal, and continue to ac-cumlnulate energy. His run wouldtherefore have a larger elapsed time,but it would have a higher, and illegiti-mate, top speed. His strategy wouldbe to sacrifice his elapsed time, andthe race, in order to achieve an illegiti-mately higher top speed -- sinceIHPSC drag races are run primarily fortop speed. This race strategy wouldviolate the intent of the "one-minuterule" (which is to allow only one min-ute for human-energy accumulation --a time limit which is consistent withreal-world conditions for practical ve-hicles). A competitor in an IHPSCtop-speed event could use the samestrategy, with the result that the runwould take longer, but the top speedwould be higher. This too would vio-late the intent of the "one-minuterule".

A simple way to insure compli-ance with the intent of the "one-minuterule" is to require that top-speed runs

and drag races be completed within anappropriate amount of time. Only therace officials would be concerned withthis additional requirement. The timelimit would be based on the time re-quired to accelerate to the competitor'stop speed over the specific distance ofthe designated course. In other words,the time limit would be proportional tothe distance of the designated course,and inversely proportional to the topspeed of a specific run. The time limitwould also include two or three addi-tional seconds to allow for the normalrange of variations in acceleration pro-files. The exact formula for the timelimit would be determined by the rulescommittee, and would then be pro-gramnmed into the timing device. Aslong as the competitors acceleratednormally over the designated course,their runs would easily conform to thistime limit. So the time limit would beof no concern to the competitors un-less they attempted to accumulate ad-ditional and illegitimate energy. A runthat exceeded a competitor's specifictime limit would be disqualified.

No feedback would be given tothe competitors regarding the time dif-ference between the actual time usedto make a specific legal rut and thecalculated time limit allowed for thatrun. The competitors would not betold how much time was left over,since doing so might encourage some-one to attempt to accumulate a fewextra pedal strokes' worth of energybefore, or while, accelerating. Also, inorder to further discourage any attemptto circumvent the "one-minute rule",disqualification of a run would occurif, for any reason, a race official sus-pected that illegitimate energy hadbeen accumnulated before or during arun. Two run disqualifications woulddisqualify a competitor from the event.Since use of the "one-minute rule" forIHPSC events would, in effect, mod-ernize the definition of HPV (by pro-mnoting the use of human-energyaccumulators), it is important that thisupdated definition be based on clearand strict standards. Including thistime limit as part of the "one-minuterule" insures that all competitors willcomply with the spirit of the

competition, and that records will bereliable and unambiguous.

Note that both the "one-minuterule" (for IHPSC events -- which useprecise distances for each event) andthe "six-minute rule" (for IHPVAsanctioned top-speed record runms, --which use unlimited distances for ac-celeration) are variations on the sametheme. Both use time limits, but thetime limits are structured differentlyunder the two rules. The "one-minutertle", by prescribing exactly how thetime is to be used, would permit theefficiency of competing HPV to bedirectly compared with one another,and would provide a good indicationof how well a particular accumulatordesign would function in a practicalvehicle. On the other hand, the "six-minute rule" would permit a competi-tor to use the available time in anyway she wished. This would encour-age competitors to further explore 1)the tradeoffs between an accumulator'sefficiency and capacity, 2) the balancebetween charging time and accelerat-ing time, and 3) the balance betweenaerobic and anaerobic activity. In theprocess, we are likely to learn a greatdeal about the application of humnanpower. Also, the differences betweenthese two competition rules will proba-bly lead a greater diversity in the typesof accumulators that are developed. Inmy opinion, such diversity should beencouraged. My hope is that HPV ofthe future will be more efficient andmuch faster than we had everimagined.

Peter A. Sharp, 2786 BellairePlace, Oakland, CA 94601, USA

AN OPPOSING VIEWAs a graduate mechanical engi-

neer with over thirty years of designexperience, and as a founding memberand past-president of a non-profit con-sulting association for which I chairedthe development of the by-laws andassociated rules and regulations, I haveread with keen interest the dueling let-ters (and article) between Peter Sharpand Tim Leier.

Human Power, winter-spring 1993-94, vol. 11/1, p.17

1_11_

In between the flights-of-falcyarguments presented, each has somevalid support for his respective posi-tion. However, I feel Mr. Sharp isleaning too heavily on the IHPVA fora Good Housekeeping type of endorse-ment and Seal of Approval.

If he has some worthwhile designsby all means go for it and developworking models for demonstration andtesting. But with regard to rulechanges (a serious business requiringstrong supportive evidence), to para-phrase the theme of Field of Dreams:if a sufficient number of designers ". ..build it (i.e. working models of merito-rious performance) and they (IHPVA)will come (to change the rules)".

William J. Moriarty, P.E. 75South Road, Hamnpden, MA 01036

CHEETAHMISCONCEPTIONS

I was one of the guys who de-signed and built the Dexter HysolCheetah. This is the bike that went68.73 mph in the 200-m sprint on Sep-tember 22, 1992. This bike has noth-ing to do with the Wind Cheetah. TheHysol Cheetah was custom designedand built from scratch mostly withcomposites. It does have a fully en-closed graphite fairing and would notbe useful for commuting. We have noimmediate plans to market the Cheetahor anything else for that matter. Justthought I'd set the record straight.

[Incidentally, the Cheetah was fea-tured on the front cover and in an arti-cle in the October issue of PopularScience].

Please feel free to address anyquestions about the Hysol Cheetah tome. I'd be happy to clarify anythingvague that is in the article. Send mes-sages direct to my e-mail address.

James R. Osborn, Lawrence BerkeleyLaboratory, JROsborn;lbl.govPhone 510 486-7052(This was taken, with James Osborn'spermission, from the e-mail hpv list-ing, and was a reply to some errone-ous comments about the C'heetah- Ed).

1994 EUROPEAN HPVCHAMPIONSHIPS

The Swiss HPV association FutureBike invites you to the European HPVChampionships, open to all HPV en-thusiasts. They are from 26th to the28th August in Laupen, a lovely littlevillage, situation about 30 km WSWof Bern, our capital, and about halfwaybetween Bern and Fribourg. The racesinclude some Swiss "specialties" suchas a mountain time sprint and a race ofover 100 km for the racers and 50 kmfor the commuters. We are also organ-izing the first HP railroad chamnpion-ships! There is a level railway 2-kmlong near Laupen. For more informnna-tion, contact me.

Jeurg Hoelzle, FUTURE BIKE, Spit-zackerstrasse 9, CH-4410 Liestal,Switzerland. FAX: 33 28 30 39E-mail:100111.211 7compuserve.com

HPV ACTIVITY IN JAPANProf Naito's HP helicopter be-

came airborne on December 5. In fur-ther trials on December 12 and 19 thetruss frame connecting the four rotorsbroke. He plans to test again in Febru-ary. I have sent you a video tape ofthe tests [and I will be sending it on tothe IltIP VA library - ed/.

Aerocepcy's new HPA, GokurakuTonbo, crashed at the end of Decem-ber during a long-distance flight.

Kinki University is constructingits first HPA. The total weight is only25 kg. Scheduled first flight is inFebruary.

Kyoto University is building a HPornithopter. It has wings and tail in aconventional-aircraft style. A fixedinner wing will generate the lift, whilethe flapping outer wing produces thethrust. Unfortunately it made a groundloop and crashed during a HP towingtest on December 12 1993. The teamis rebuilding it for further tests in thespring.

I have good news about a racenext summer: it will be in Lake Ha-mana and will be for solar boats.

RIM HEATINGI much enjoyed Dave Wilson's ar-

ticle on downhill braking and wassomewhat surprised and edified at howlow the speeds were for maximum rimheating. I suppose that I over-ratedradiational cooling compared withforced-air cooling - but I'm no experton cooling. The hoary advice to pumpbrakes to reduce rim heating is oftenrepeated, without any analysis of thephysics. It seems to me that whetheror not this advice is good depends onthe rate of heat conduction through therim to the tire compared with the rateof cooling at the rim's outer surface.Since aluminum has very high heatconduction, I would think that pump-ing the brakes would give higher peakrim temperatures than steady braking.With hollow steel rims, the effectmight be beneficial, though, becauseheat conduction to the tire is slower.Certainly, J. S. Forester's advice to useboth brakes equally to reduce heatingis good, but then Forester knows hisphysics.John Allen, Waltham, MA, USA(e-mail johla(4cfal 65.harvard.edu).

REVIEWYAMAHA LAKE RUNNER

In 1993 Yamaha introduced a ped-aled catamaran called the Lake Run-ner, and made a short videotapewidely available. It was discussed onthe Internet HPV mailing list. DuaneKlinge wrote that he owned a pre-production version called the WaterGlider. It has hulls and seat made ofKevlar and weighs about 60 Ibm. Itwill do 8 - 10 mph in a sprint but aver-ages closer to 5 mph for normal cruis-ing. The single gear is surprisinglysimple and more durable that it ap-pears on the video. He has had it outin small-craft advisories (30-40-knotwinds) on 6-ft waves on Lake Supe-rior, as well as using it on many lakesand rivers. "From what I have seen todate there is nothing that matches it forprice, performance and stability".

Another writer, Dave O'Brienfrom Toronto, wrote that it seemed funto ride, but he thought that the intro-ductory price, $1700, was a bit steep.

p.18 Human Power, winter-spring 1993-94, vol. 1111

1_11____1_11__111_1_1_1111

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EDITORIALSThanks!

In the first part of 1993 I was onsabbatical. I and you were lucky tohave a volunteer to produce HumanPower: Patrick K. Poole, late of theU.S. Navy submarine service and aprofessor at Annapolis. Pat has starteda consulting company, and editing HPtook a great deal of time from his busi-ness. We are very grateful. Pat under-took to produce two issues: vol. 10/3,principally composed of material thathad come to or from me, and vol. 10/4,devoted almost entirely to HP subma-rines and the Third International HPSubmarine Races in June 1993. Hedid a beautiful job.

Thanks also to John Raine of theUniversity of Canterbury, New Zea-land, who sent along a much-appreciated paper on the Tricanter in199 1, and subsequently asked me if Iwould be interested in an Erskine Fel-lowship there. It was my father's olduniversity, and all I had to do was toget Ellen's agreement before replyingenthusiastically in the affirmative.

I helped John in one course (weset the students to design a HP gardenshredder) and taught another; Ellenand got to know most of the ener-getic HP community, which is produc-ing some very interesting designs; andwe accepted a very generous offerfrom Dave Kelly to use his GaryFisher mountain-bike tandem on a1200-km tour around and over theSouthern Alps. We had, as might beexpected, a fantastic trip.

Wins and losses.Camondale's "trial-balloon" re-

curnbent (a long-wheelbase machinewith full suspension and above-seatsteering) has many hoping that this isthe breakthrough for which we havebeen hoping. Vic Sussman wrote onthe e-mail network that recumbentsseem to be catching on: "AmericanHealth magazine has a picture ofKathie Skewis' ReTrike and extols thevirtues of 'bent biking. Dick Ryan'sVanguard is featured in Men's Health.And on October 17, USA Weekend, asupplement published by USA TO-DAY, will feature a small story about'bents, illustrated with a small pictureof a guy (me) holding up his GoldRush Replica. USA Weekend has acirculation of 35-million .. whichshould make Bob Bryant very happy"(because the Recumbent CyclistMagazine was listed as a source). AndPopular Science had the Cheetah as its

cover photo and lead article inOctober.

On the other hand, Bicycle Guidemagazine has been sold again, and thenew publisher announced that BG wasgoing to concentrate on traditionalsport cycling, and therefore less cover-age of unconventional machines.

Rules"Clever driving makes for a more

interesting sport than cunning design".So ended an "Economist" comment onthe increase in popularity of the Indy-Car circuit and a decline in FormulaOne, which "has become too techno-logical for its own good: the teamwith the latest gizmo fitted to its carinvariably wins." Should we worryabout this happening to HPV racing?The IHPVA was formed as a reactionto what were seen as restrictive rulesfor bicycle racing. Originally therewas one IHPVA rule: no stored en-ergy. Now we have a hodge-podge ofstrange rules ourselves, including themaximum favorable slope and wind toqualify a speed-record attempt, mod-eled after the conditions at the now-long-gone site of our early speed trials.And we have suggestions to revise therules to make them more logical: Al-lan Abbott has proposed a new cate-gory of top-speed records and PeterSharp proposes allowing stored humanenergy in some races. We should wel-come all proposals. When I play ten-nis I marvel at how perfectly the courtand net have been chosen to give noadvantage for one type of play overanother. There were decades of ad-justments until that happy situationwas reached. We can expect no less.

Near-custom bicycles.Two developments from Japan

could change the bicycle industry.Panasonic sells about 700,000 bicyclesa year in Japan. According to an arti-cle by Trudy Bell in IEEE Spectrum,an increasing proportion of these aremade to order through flexible manu-facturing using CAD/CAM and robots.A customer orders a bike at a shopwhere her/his measurements and com-ponent preferences are noted, andevery frame tube and angle is auto-matically cut and shaped and tack-fastened. A veteran craftsman accom-panies the bike and works on the finedetails. There are 18 models inchrome-moly steel, aluminum alloyand carbon fiber, and enough otherchoices to give over I 1-million possi-ble variations. The models do not,alas, include recumbents yet.

On another front, Yamaha is intro-ducing its PAS: "power-assist sys-tem". It is a battery and auxiliarymotor on a regular bicycle. The bikeis ridden normally. When the PASsystem is engaged the motor assists inproportion to the pedaling effort. Themotor rated power is 235 W, so that itcan match a hearty humnan-powerinput.

HPVs or VELOMOBILESThere are exciting developments

in Europe. I have long been an advo-cate of rail-borne HPVs being the nextspeed-record setters, and the decisionto hold rail-bike races in Switzerlandthis year (see letters) is exciting.There is also a move to use Velomo-biles in place of HPVs. I'm not as en-thusiastic about this switch, butgrumpy old men were never able tostem the tide of popular change in lan-guage. HPV is descriptive. Somepoint out that "automobile" appliesmore to the HPV than to a vehiclepowered by an engine, but it's too lateto fight that battle. As far as Velomo-bile is concerned, the people's will willbe done.

An index and a decade.With this issue we are at last up-

dating the Human Power index. Itcontains all the articles entered underthe topic and under the principalauthor, and some letters and reviews.I did not include references to all thetopics within each article: the lengthof the index would have becomeunwieldy.

I also included a summary of theissues of Human Power since it startedwith the winter 1977-78 issue; of thenumbering system used; and of theeditors. With this issue I am complet-ing ten years in that post. I'm not try-ing to hang on to the position. Therehave been no rivals vying to take on ajob that takes a great deal of time andsome expenses and has no pay. Ifsomeone with a burning desire to dobetter does turn up, I'll happily handover the reins. Meanwhile I enjoyworking on something that I believecontributes to present and future hu-man welfare: the effects of the HPVmovement are all positive, as far as Iknow. And I'll try to do better. InJuly this year I go on emeritus status atMIT, which means, I hope, less unre-lenting pressure from competingdirections.

Human Power, winter-spring 1993-94, vol. 111/1, p.19

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