THE KREMER WORLD SPEED COMPETITION

AIMS

In the early 1980s there was much discussion by the committee of the then called Man-Powered-Aircraft-Group of the RAeS about where we go from here, whether the time was ripe for another competition, and if so what form of competition. The figure eight had been flown. The English Channel had been crossed, and hence in some ways the hopes of 1957, and of centuries before, had been more than realised.

However,

1. Muscle-powered-flight was still impractical,
2. Flying was restricted to freak calm weather, and
3. The aircraft were of monstrous size.

Apart from the obvious need for improvement in these ways there were also the hopes of

4. Initiating a sport,
5. Maintaining the momentum of development,
6. Continuing to encourage the pursuit of excellence, which was seen to imply high-technology,
7. Tending towards enabling the man-in-the-street to be the man-in-the-air, which was seen to imply low-technology, &
8. Prizes being awarded on a wider basis than previously.

SETTING-UP

With these aims in view, a working group, the majority of whom had designed successful HPAs, was formed under the chairmanship of Nick Goodhart. A speed competition was chosen as the most likely event to promote as many as possible of the above facets of HPF, and the course was carefully planned in the usual way, with the intention being that it be just beyond possibility at the current state-of-the-art. Henry Kremer was approached for the financial support which he most generously provided.

TROPHY

Also Henry Kremer had observed, when in the auction rooms of Christie's of London, an impressive bronze sculpture of a winged man striving forward with eyes determinedly fixed on the horizon. Seeing this as representing progress in human-powered-flight he promptly acquired it and presented it to the RAeS, and it now became The Kremer Trophy. Inscribed "L. ALLioT", it is of unknown origin. A replica of the trophy was presented to each successive winner, along with a share of the prize money. The spirit of the competition was, with the foregoing eight points in mind, to aim for maximum speed around a circular mile. It was believed by some that the development of stored-energy (see glossary) might be one path towards a more practical vehicle, although anything taking a long time to wind up was seen as impractical, hence a rule allowing a maximum of 10 minutes for storing energy. At that time, there was no experience of stored energy on HPA since the bungee launches of Mufli 47 years previously. The rules were drafted by Martyn Pressnell and after full discussion in committee, were approved by the Society's council, and published on 4th May 1983 by the Society.

RESPONSE

The response was overwhelmingly fast compared with other competitions, as the following narrative shows.

THE RACE

The fastest previous plane, Jupiter, flew at 20 mph. This is equivalent to a mile in three minutes. But to win the first prize of £20,000 this speed must be exceeded around a triangular course. To win a subsequent prize, an entrant must improve on the previous time by 5%. And subsequent prizes are only £5,000. Hence there is a big incentive to be the first. After that, a faster speed is needed for less money. The Chrysalis team and the Gossamer Condor team had co-operated in 1979. It was a Chrysalis designed propeller that had crossed the English Channel, and it was Condor Mylar that covered the vast areas of the wings of the Chyrsalis biplane. In 1983, with news of a new competition, they saw each other as potential rivals. At a meeting in February Paul MacCready, Condor initiator, declared that he would not be competing, but this was met with scepticism by John Langford and others at MIT who had been involved with Chrysalis.

4 MAY 1983 Royal Aeronautical Society Human Powered Aircraft Group, the competition's organisers, announce the rules. Following the publication of these rules, both Langford and MacCready promptly indicate to the organisers their intention to enter the speed competition.

5 MAY 1983 Langford and some of the old Chrysalis team at MIT hold the first design meeting for the aircraft they will call the Monarch. They decide to build a very simple machine, just capable of a 3 minute time.

27 MAY 1983 The old Chrysalis foam-slicer is dug up and restored. The first Monarch parts are made.

28 MAY 1983 MacCready's team, which includes some of the Condor people, start to design their entry for the Kremer World Speed Competition, which will be called the Bionic Bat or Gossamer Swift. These people have the experience of many Condor aircraft, and they have the carbon-fibre technology which they developed.

 MAY 1983 Wayne Bliesner starts to add a twisted-rubber energy storage system to his Man-Eagle. This plane had already flown the previous year and is fast and controllable.

14 JUNE 1983 Knowledge of Monarch becomes public

27 JUNE 1983 Construction of Bionic Bat starts

10 JULY 1983 Knowledge of Bionic Bat becomes public

4 AUGUST 1983 Monarch rolls out - and rolls over, causing damage to the airframe.

14 AUGUST 1983 Repaired Monarch makes first flight. This student’s aeroplane is made from aluminium tubes and plastic foam, but carries ingenious energy-storage gear enabling pilot to control motor assistance during "play-back" in flight.

20 AUGUST 1983 Bionic Bat makes first flight. Seen casually from a distance, Bat looks similar to Monarch. But pilot seating, propeller position and wing bracing all differ between the contesting machines.

23 SEPTEMBER 1983 Monarch crashes on development-flight. Fuselage wrecked.

25 SEPTEMBER 1983 Bionic Bat flies course in 2 minutes 39 seconds. Claim is submitted to organisers. Monarch team know they will never beat this by 5%.

13 OCTOBER 1983 Parker MacCready, Bionic Bat pilot, invited by John Langford to describe his experiences to Monarch team.

15 OCTOBER 1983 Monarch team store their aeroplane away and start to redesign the fuselage, which had been a source of problems anyway. Pilot seating will now be recumbent, same as Bat. New version will have variable pitch propeller, an important item when motor assistance is used (see Monarch).

23 NOVEMBER 1983 RAeS disallow the Bionic Bat claim for technical reasons concerned with energy storage.

DECEMBER 1983 A few parts made for Monarch variable pitch prop

JANUARY 1984 Bionic Bat is being modified with a new electrical system, 5 lb (2.3 Kg) heavier. Parker MacCready continues to practice the course with this new system. Gunter Rochelt starts construction of Musculair. This will not use stored energy, being powered only by Holger Rochelt for prize attempts. Man-Eagle is modified to use electrical system.

FEBRUARY 1984 New Monarch fuselage being built secretly, road-testing at night.

29 FEBRUARY 1984 Paul MacCready declares he will dispense with stored energy, and modify wing instead. Span will be increased from 48 to 55.5 ft (14.6 to 16.9 m).

4 APRIL 1984 Langford's new fuselage completed. Plane flies again renamed as Monarch B.

APRIL 1984 MacCready new motorless variant flies as Gossamer Swift.

3 MAY 1984 Pilot Frank Scarabino attempts to fly Monarch B around the course, but new variable-pitch propeller is wrongly set. Attempt aborted.

5 MAY 1984 Scarabino tries again. Crosswind ends flight.

6 MAY 1984 Scarabino completes course - in 3 minutes 0.43

7 MAY 1984 Another attempt with the Monarch B, but Scarabino lands from exhaustion part way around. Scarabino rests for 3 days.

11 MAY 1984 Monarch B team prepare for another attempt. The official observer watches click to denote the commencement of the 10 minute storage period. Frank Scarabino starts to pedal to charge up the batteries. If more than ten minutes are spent on the ground then this excess time gets added to the flight time. The ten minutes are coming to an end when a door zipper jams, the struggle to unsnag this causes precious seconds delay, and Frank takes off 5 seconds late. To get the prize he will now have to fly the course in 2 minutes 55. He climbs to clear the required height of two meters at the starting line and heads for the first turn which is at the end of a runway on Laurence G. Hanscom Field, Bedford, MA. He clears the two markers which represent the short side of the triangle and straightens up for the half mile stretch past the MassPort Civil Terminal, continuing past the control tower towards the last turn. With the new electrical system on Monarch he can ration the amount of charge coming out of the batteries. The idea is that the batteries, his legs and three minutes all get exhausted at the same time - except, there is five seconds to be made up. It isn't just leg work. It isn't even just leg work and also flying a plane as well. The electrical system is another thing to have to think about. On the last turn he opens the "throttle" slightly to get more help from the motor. Now to straighten up for the last quarter mile stretch over the runway and the climb to two meters at the end. Monarch B crosses the line 2 minutes 50 seconds after crossing it the first time; he has made up the five-second-late start. A time of 2 minutes 54.76 seconds is recorded. The Monarch B team have won the £20,000 first prize.  John Langford will be able to take his pick of the replicas of the Kremer Trophy. The Monarch team retire from the race, considering that their plane has done the best it ever will. But while others compete for subsequent prizes, they have a longer course in mind - see below.

 JUNE 1984 Paul MacCready decides to use stored energy after all. The team prepare an improved system that uses the motor as the generator. This means only one item and less weight to carry. But the increased span remains.

19 JUNE 1984 Holger Rochelt takes Musculair round the figure-eight course, winning the prize for that competition. Now the Musculair can be refined for the speed course. A time of only 4 minutes 5 seconds for the figure-eight shows the potential of this plane.

JULY 1984 Bionic Bat with new motor and 55 ft (16.8 m) wingspan rolls out and makes practice flights. This aeroplane was built from carbon-fibre tube by professionals, and has been refined over several variants. But the electric motor only has an on/off switch.

18 JULY 1984 Parker MacCready flies course in 2 minutes 43 seconds, gaining second prize of £5,000 with the Bionic Bat. The length actually flown to clear the marked out triangle depended on how wide a turn each pilot made, but it can be considered as nominally a mile. On this basis Parker's speed was 22 mph (9.8 m/s).

3 AUG 1984 Musculair gets round speed course in 2 minutes 45 seconds, an improvement on Monarch's time of more than 5%. Rochelt hasn't heard of the Bionic Bat success and thinks he has second prize.

AUG 1984 Continual training and refinements of the plane including reducing tail area improve the Musculair performance.

21 AUGUST 1984 Holger Rochelt completes course in 2 minutes 31 seconds. Speed based on a nominal mile is 24 mph (10.7 m/s).

NOVEMBER 1984 MacCready makes no more major changes to the aeroplane but calls in pilot Bryan Allen, who pedalled the Condors on their prize winning flights.

2 DECEMBER 1984 Bryan Allen clocks time of 2 minutes 23 seconds, improvement on the previous record is 5.8%. A nominal-mile-speed of 25 mph (11.2 m/s). The second time that the Bionic Bat has earned a prize.

FEBRUARY 1985 Musculair is severely damaged in road accident.

1985 Rochelts and Schoberl decide to design and build new plane specifically for speed course. No energy-storage will be used. Good aerodynamics, neat structure and accurate wing-profile. Elliptic chain-wheel.

During this summer Wayne Bliesner, who has been training hard and improving his energy-storage-system makes eight attempts on the course. It is now necessary to complete the course in 2 minutes 15 seconds. He can't quite get round in the required time.

AUGUST 1985 Musculair II nearly complete. Rochelts bring plane to England, hoping to fly at Milton Keynes festival. Musculair II completed at Cranfield, but weather precludes flight. Plane displayed indoors at Milton Keynes.

1 OCTOBER 1985 Holger Rochelt flies Musculair II round speed course in 2 minutes 21 seconds. This is the fastest yet, beating the Bat's 2:23, but not beating it by the required 5%.

2 OCTOBER 1985 For today's record attempt, Holger warms up for two hours and is psychologically prepared by an experienced bike-racer. He beats his yesterday's record by an amazing 19 seconds, covering the course in 2 minutes 2 seconds, thereby qualifying for a Kremer prize, the Rochelt family's third award. This time represents a nominal-mile-speed 30 mph (13.4 m/s), a 15% improvement on the previous winner, 50% better than original target at start of competition.

1986 RAeS close competition, but course still recognised by FAI for speed records

SPEED COMPETITION SUMMARY OF RESULTS

Compare the table below, showing dates of first flights and prizes for this competition, with the fact that after the announcement of the first Kremer Competition, the figure eight, it was 2 years before the first flights of SUMPAC and Puffin, and 18 years and 25 years respectively before prizes were won by the Gossamer Condor and the Musculair I.

And as it transpired all of the eight basic criteria mentioned above were satisfied and hence it was a successful competition, as the following points show :-

 1/ muscle-powered-flight had been impractical. The Musculair II was able to perform at air-shows.

 2/ flying had been restricted to freak calm weather. There was not as much progress as might have been expected from the usual rule that a faster aircraft can operate in stronger winds. John Langford of the Monarch team reported  "Weather was always a problem. --- Final weather checks were made at Hanscom about 3:30 am, and a go/no go decision made about 4:00. - - The aircraft was never taken out in winds higher than about 4 mph (1.8 m/s) although gusts of up to 9 mph (4.0 m/s) were recorded during some flights. Long turns and Kremer courses were not attempted in winds above about 1 mph (0.45 m/s). Flying was usually completed by 7:00 am.", and "The Monarch is clearly a transitional aircraft. It is no longer a fragile gargantuan and yet neither is it a `practical' ultralight aircraft in any sense of the concept". (Langford 1984). Compare the flying usage of its predecessor the Chrysalis which was half the speed of Monarch, yet its first flight was in a wind of 8 mph (3.6 m/s). (Chrysalis was in fact the slowest aircraft ever to fly). Langford wrote "Eight pilots made 24 flights on June 24 [1979]. Thereafter, the aircraft was rolled out whenever the weather was good and people wanted to go. When the weather remained calm, the sessions extended far into the morning; one day in July a record 11 pilots made 56 flights in Chrysalis. This particular session concluded when the wind speed consistently exceeded flight speed, but not before the aircraft demonstrated hovering and even backward flight." (AIAA Student Journal Spring 1981).

 3/ the aircraft had been of monstrous size. Seeing Musculair II, the author was impressed particularly by the compactness of the plane and the speed with which it could be rigged. The wingspans and areas shown in the Table indicate the size of HPA of this period in general.

 4/ initiating a sport. What could more define sport than two teams competing and alternately creating new world speed records. The records were accepted by the FAI. Seen from outside, the prize-flights were more pilot-oriented, although the differences between the machines made the contest far from a "class-design".

 5/ maintaining the momentum of development. The table above shows in how few years the performance of HPA was increased during this competition. John Langford compares the race to be the first winner in the speed competition with the race of 23 years previously:- "The contest between the Monarch and the Bionic Bat played out an old and familiar contest that first occurred in the race between students at Southampton (SUMPAC) and professionals at de Havilland (Puffin) to make the first human-powered flight in Britain. As in the 1961 race, the students triumphed in 1984." And in both contests, both the students and the professionals were eventually beaten by projects initiated by families,

Roper(Chris & Susan, Jupiter) 1972 ,

MacCready(Paul & Parker, Gossamer Condor) 1977 and

Rochelt(Gunter & Holger, Musculair II) 1985.

 6/ continuing to encourage the pursuit of excellence, which was seen to imply high-technology. The Musculair II with custom-aerofoil, carbon structure and monocoque wings was a quantum jump ahead of anything that had previously flown. The aerodynamic merits of this design were demonstrated not only by its making the biggest increase in speed, but also that this was without using stored energy.

 7/ tending towards enabling the man-in-the-street to be the man-in-the-air, which was seen to imply low-technology. This might appear to be incompatible with 6, yet in fact the competition promoted development in both directions. Monarch, the first winner was built with little more equipment than the box that the light-alloy tubes were delivered in, ( The box was converted into an etch-milling bath ) and the cost of the project was estimated at $6760 net ($2375 of this being energy-storage costs). See Monarch, and (Langford 1984).

 8/ prizes being awarded on a wider basis than previously. All the prizes went to people who had built and flown aircraft before, and the five prizes went in only three directions. However this aspect showed improvement as did all the others. The competition was closed in 1986 when the committee felt that no further signficant improvements in flight speed were probable and the Kremer funds could more usefully be deployed in other ways.

BATTERIES

Was anything learnt about stored energy that could be used in HPA or in human-powered-vehicles in general ? The author had hoped that maybe something would be learnt towards a practical energy-regenerative braking system for bicycles. The kinetic energy would not be wasted in just heating up the brake-blocks and rims, but put into storage where it would boost acceleration when the rider restarted. Such a scheme would be appreciated by cyclists particularly the professional cyclist-couriers of London.

The various options for energy-storage were seriously analysed by the entrants and the conclusions were that the only two viable systems were batteries or twisted rubber, and that a third viable option was to omit energy-storage altogether. Hence only these systems were tested. Anyone thinking of organising a competition which allows stored-energy should know that when applied to batteries the word "uncharged" must be carefully defined. The organisors consulted with many battery experts at Government research institutions and there is a supplement to the rules on this point. The first claim for a speed record was disallowed for technical reasons but in so doing initiated the establishment of a universal standard for discharge of batteries when employed for stored energy. Various innovative systems were developed by both the Bionic Bat team and the Monarch team to charge in ten minutes and discharge in less then three, without losing efficiency on either occasion or carrying a heavy battery. Also developed was the ability to use the dynamo as the motor, and to enable the pilot to monitor the assistance from storage without requiring so much concentration as to detract from flying and pedalling ability. Details of these are in (Cowley 1985) and (Langford 1984)

REPORTS

Goodhart surveyed the competition at a symposium of the RAeS when several prizes and trophies were presented (RAeSMPAG Dec 1985). (See also Gremmer 1985).

FUTURE

Since then, a further vindication of the competition is that people from all the three teams who made official entries, who in fact were all winners, gained experience enabling them to go on to (1/) Daedalus, (2/ and 4/) a battery operated full-scale-model pterodactyl to test evolutionary theory and star in a film, and the Helios solar powered long duration pilotless aircraft and (3/ and 5/) a delta-wing single-place aircraft somewhat between a glider and a hang-glider. Later developments in rare-earth motors and fast charge batteries indicate that both the Bionic Bat team and the Monarch team were on the threshold of new progress in electric power as an aid to HPA. Model aircraft have proven the point over and over in the late 1980's and the Paris, France to Manston, England flight by solar power by MacCready with Solar Challenger heralded yet another benchmark in electric power for very light aircraft.

 MONARCH A & B

Chrysalis designers Mark Drela and John Langford had been intending to build another aeroplane. They had made sketches and even chosen a name. Monarch is named after the monarch butterfly, the next stage after a chrysalis. Hearing of the Kremer World Speed Competition, Drela and Langford proportioned and optimised this new plane for it. This meant a much smaller machine than their previous one. With the aid of Scott Clinton, Juan Cruz, Mark Drela, Steve Finberg, John Flynn, Whitney Hammett, Geoffrey Landis, Barbara Langford, John Langford, Tom Roberts, Frank Scarabino and Rick Sheppe, this aeroplane was flying within 88 days of start of construction . Constructional techniques were similar to those used for Chrysalis, although the layout was very different. Unusual on the Monarch was the wheel drive system. On an HPA wheel with chain-drive like a bicycle, the number of times the chain makes a complete circuit during take-off is in two figures. When in flight it is a nuisance, turning the wheel for no reason. Why then does the wheel-drive-chain need to be endless ? The Monarch team realised it didn't and built their wheel drive accordingly on the principle of a glider launching winch. Considerable sophisticated analysis went into the sizing of this aircraft. An early design decision was to use a simple structure and an ingenious electrical system. For a comprehensive & detailed account of a project from conception to the winning of a Kremer prize, John Langford describes the Monarch in his thesis (Langford 1984). The plane is also further mentioned above in the narrative of the speed competition.

 BIONIC BAT/GOSSAMER SWIFT

Team members were Bryan Allen, Bob Boucher, James D Burke, Martyn Cowley, Adam Curtin, Bob Curtin, Bill Dodson, Roy Haggard, Lance Inoue, Parker MacCready, Paul MacCready, Tyler MacCready, Ray Morgan, Taras Kiceniuk, Les King and Roger Sinsheimer. The Bionic Bat was yet another aeroplane from the MacCready stable to win a Kremer prize, this time in the speed competition, and this time two prizes, (see above). This plane was in fact the first to complete the circuit in the specified time of three minutes but was disqualified because of technicalities of the energy-storage. Configuration was a recumbent pilot in pod under a high wing. propeller was concentric around the tail-boom just behind the pod, as on the Icarus. Such a design was vindicated when, on flight tests, the drag was less than estimated. The team consider that this may have been caused by the effect of the propeller in reducing the drag of the fuselage. Electrical storage was by Astro samarium cobalt Astro 40 DC electric motor/generator and a battery of 16 Nickel-Cadmium rechargeable cells returning an overall storage system efficiency of 20%. The approach to pilot safety differed widely from that of the early large Condors, where the pilot would jump out if anything broke. On the Bionic Bat, the structure was designed to not break, and the pilot strapped in.

Bionic Bat. REeS collection

FLIGHT ENVELOPE

The wings were designed to carry 3g or minus 1g. Minus 1g represents inverted flight. The Bionic Bat never actually flew upside down, but it was strong enough to have been able to. For safety, a flight envelope is drawn so that any actual anticipated manoeuvres are well inside it. The fuselage was designed to withstand a 4g vertical landing load or a 6g head-on load. The wheel was designed to withstand 1g aft from braking with a 0.7g simultaneous side-load. The nose wheel was designed for 1.5g vertically with a 0.7g side load. The maximum airspeed catered for by the structure was 50 mph (22.4 m/s). The design manoeuvring speed was 40 mph (17.9 m/s). This is the maximum speed for which the structure permits full control deflection. Stall at 1g, i.e normal flight was anticipated as 25 mph (11 m/s) (see Flight Envelope in Glossary). The next step was to decide on the lightest type of structure which could carry these loads. Wire bracing, as used on many machines, enables a lighter wing spar, but at the expense of extra drag. That means more power from the pilot. An optimization procedure will indicate whether a cantilever wing or a wire-braced wing will lead to a lower power-requirement. In the case of Bionic Bat, the unusual answer was that the very short strut characteristic of the Bat would be best. (This choice may also have been influenced by consideration of ease of assembly and rigging). Materials used were carbon-fibre tubes. Tubes are most efficient when of large diameter and thin wall. The spar tube on this plane is nearly the depth of the wing, and so thin that it would buckle locally unless supported. Some support would be provided "free" by the wing ribs, without any extra weight, but in addition internal discs were added midway between ribs. The tail-boom tube had to be stabilised externally, since control cables ran inside. Another method of tube stabilization considered by the team, but not used, is to stabilise externally with a layer of Nomex honeycomb, then a layer of Kevlar to form a sandwich, as used on HPV road vehicle fairings and the Challenger aircraft. In order to protect the pilot from carbon splinters, tubes in the area of the pilot were wrapped with bonded-on Kevlar cloth which does not splinter if broken. Fore and aft loads on the wing of the Bat were carried by what was effectively a horizontal "I" beam. The tube-spar was one boom, the trailing-edge-member the other, with the Mylar covering acting as the web (for free again) and the ribs being the stiffeners.

 WING AERODYNAMICS

A section to suit this plane was derived from Robert H.Liebeck's LH 110 aerofoil. The wing area was changed several times during flight trials.

 BIONIC BAT VARIANTS

Control surface areas also varied. The April 1984 variant had a larger propeller diameter. Roy Haggard also piloted the Bat.

So, dear reader, if you learn nothing else about the aerodynamics of human-powered-flight from reading this book, just remember that the shortest wing that ever supported a human was 42 feet (13m) and that the very next month this was extended to 48 ft (15m) and later to 55ft (17m).

EFFECT OF MOTOR ASSISTANCE

Martin Cowley writes "An advantage is a constant speed effect, if the pilot relaxes his pedalling, the motor provides a larger proportion of the power required to fly. If the pilot increases output, the motor reduces its contribution. However, this is a mixed benefit,as it now becomes difficult to `add power' merely by pedalling harder" On the Monarch B, the use of a variable pitch propeller enabled this to be overcome. Total power output was controlled by varying the pitch of the propeller. The pilot put in some of this power, and the motor provided the remainder. Gossamer Swift, the April 1984 variant, was without the complication of energy storage and compliance with the competition rule relating to energy storage that this involved. However, the team returned to the use of electrics with a single motor which also served as the generator. ( cf Musculair II which used no energy storage). Bionic Bat is also further mentioned above in the narrative of the speed competition.

MUSCULAIR 1 (continued)

With more training and some refinements to the airframe, Holger was ready for the next competition. But the speed he now needed to fly at to get a prize had been increased by 16%, because meanwhile two prizes had been won. Original target was 180 seconds. Now, to get a prize, Holger must pedal round the course in less than 155.12 seconds, (95% of the current record of 163.3). He did it in 151.38 seconds with no motor assistance. The Rochelts had considered using stored energy, then decided that it was a wasteful impediment.

Musculair I. RAeS collection.

PASSENGER FLIGHT

Holger's sister, Katrin Rochelt weighed 62 lb (28 Kg), the same as the plane. A makeshift seat was taped to the back of the main fuselage vertical tube. She climbed in behind her brother and she held on tight. Musculair took off and made a flight of 550 yards (500 m), reaching a height of 16 ft (5 m) with the wings deflecting considerably more than usual. The incredibly modest Holger, winning pilot for three Kremer awards said later "I just had to pedal a little harder". Bionic Bat then cut 8 seconds off Musculair's time, but before the Rochelts could beat this latest record and bring the trophy back home once more to Germany, Musculair was seriously damaged in a road accident, so they decided to build another plane.

Holger Rochelt flying with his sister as passenger. RAeS collection.

MUSCULAIR II

This aircraft was brought to England when nearly complete, in the hope of flying at the Milton Keynes 1985 "Zapple" Festival of Human Power. Final details of construction were done at Cranfield College, and the plane was brought and displayed indoors at the festival, but bad weather precluded flights. Aerodynamically optimised by Ernst Schoberl, and test flown by Holger Rochelt and Peer Frank, with project management by Gunter Rochelt, this plane was advanced for its time. It was designed to fly the speed course in two minutes. Schoberl writes that design and construction of Musculair II was relatively simple since the team "merely" had to adapt proven concepts for the new conditions ( another modest man talking ).

Musculair II flying. RAeS colection.

WING

The section was derived from the Wortmann section FX 76 MP by Dieter Althaus at the University of Stuttgart to suit the particular Reynolds number and lift coefficient anticipated. Musculair I had experienced torsional problems. As described it had needed to be stiffened by the addition of rovings. For the II the team opted to skin the wing all over with a fibreglass/foam/fibreglass sandwich. This would also hopefully produce an accurate surface finish. The wing surface did indeed look incredible, as though it had been carved out of a block of aluminium. Performance indicated its good characteristics, but it suffered an imperfection as mentioned below (See Cyclair). The upper skin dimpled between the ribs in flight except at the spar position where the spar restrained it. Thus, in a chordwise direction, there was not a smooth curve. Schoberl considers that without this defect, an even greater extent of laminar flow could have been achieved. The main area of the fuselage fairing used the same material as the wing-covering, but moulded to double curvature. The shape had been arranged so that the windscreen was single curvature, this is lighter and enables a better view (the author copied this concept in the design of the Bluebell III road vehicle). On Musculair II the windscreen was removed for pilot access, and then taped in place. Musculair II had carefully shaped wing-tips to reduce induced drag, and a non-circular chainwheel which Schoberl claims improved power output by about 5%. All details on the plane were neat, ingenious and light. It could be rigged in 10 minutes. The team were seen to be in good spirits and not exhausted at the completion of construction. The plane was more tricky to fly than the I, but on October 2nd, Gunter flew it around the speed circuit in 2 minutes 2 seconds, winning the fifth and final Kremer Speed Prize. Also recognised by the FAI, the Musculair II is currently the holder of the World Speed Record. Gunter Rochelt offered to produce copies of Musculair II for sale at $25,000 (1985).

 MAN-EAGLE

In 1982 Wayne Bliesner, who had previously built and flown several HPA, (see above) was perfecting a new wing design. He set up an optimisation computer-program which indicated that a span of 110 ft (33.5 m) would be best. He then modified the FX63137 aerofoil to suit the conditions of flight, naming the new section WBT3134, which in theory at least has considerably better characteristics. This wing as originally designed was intended for long distance flight. This wing was built, using a carbon-fibre tube spar, rib-spacing of 3 inches and fitted to his existing Bliesner 7 fuselage complete with its V tail.  Tests showed that the flow over the wing was laminar back to 65% on the upper surface. Bliesner advises that the utmost care must be taken on the wing surface. The wing tip deflection was fifteen feet (4.6 m), and it became clear that this had to be reduced. This was first cut to 74 feet (22.6 m) and then to 63 feet (19.2 m). The resulting aircraft, the Man-Eagle 2 was found to require much more power to fly than would be expected of measurements made of the drag. This difference was traced to losses in the drive and also because the propeller had not been designed to be compatible to the reduced wingspan and was operating in a stalled condition. In particular it was not absorbing peak power. At this point in the development of the Man-Eagle, the Kremer World Speed Competition was launched, and Bliesner decided to make his next variant suitable for this. The "V" tail of the previous designs was rejected. The new plane had a pod & boom fuselage with the propeller mounted in front. The pilot was recumbent, and the boom was low, with the fin above.  Experience with previous aircraft indicated the benefit of a propeller capable of absorbing peak power without stalling, and 3/4 of a horsepower (600 w) was allowed for, in the new propeller.

STORAGE SYSTEM Wayne Bliesner first fitted a twisted-rubber energy-storage system, just like a rubber-powered model-aircraft. propeller hub was in front and just above the pilot, so the strands of twisted rubber were above the head. Bliesner discarded this for safety reasons, not relishing the result of a strand snapping and whirling so close. He installed an electric system which was more reliable but not so efficient as the rubber (other aircraft have used twisted rubber, but housed inside the tail-boom see Swift).

PERFORMANCE On some occasions, Wayne Bliesner took Man-Eagle out of the hangar alone, climbed in and made a flight completely single-handedly (as he had done with the Bliesner 5). As tests continued, a group of 2 or 3 ground crew provided a very safe and reliable combination. To achieve a record performance, a pilot needs to train physically. This, he declares, is where he has found difficulty. If a pilot is chosen who is already athletic, then the project already stands a chance in a competition. If there is only yourself, and you are only averagely athletic, then you will need to give considerable time to training. Between 1983 and 1986 he developed his power output from that of an `average fit cyclist' to a third of the way between this level and that of a `champion athlete', but states that this diversion of effort did compromise the project.  The plane made hundreds of controlled flights during 1985, with a total flight time of over three hours, and on one occasion completed 90% of the speed course in 2 minutes 5 seconds. This was at a time when 2 minutes 16 was required for a prize. Following the closure of the competion, Wayne Bliesner concentrated on streamlining the fuselage pod and produced a very smooth shape for the Man-Eagle 4.

MAN-EAGLE VARIANTS

In all cases the wing was of WBT3134 section, with a carbon spar. The fuselage used for Man-Eagle 1 was that of the Bliesner 7, but with a new propeller. The wingspan was successively reduced as shown. The wing position was high in all cases, and on Man-Eagle 4 was separated from the pod by a short strut.