KREMER FIGURE-EIGHT COMPETITION ( continued )
A prize of £ 10,000 was still available in 1980 for this course. The first figure-eight had been flown by Bryan Allen in the Gossamer Condor, in the USA. The rules stated that an entrant for the competition must be from a different country. The competition was to close at the end of June 1984. Three aircraft raced to beat this date, and each other.
The HVS was designed by Hutter, Villinger and Schule. Franz Villinger had been responsible for the Mufli 48 years previously. Wolfgang Hutter had designed gliders and Wilhelm Schule had constructed airframes. With the experience of the designers, and with backing from industry a neat and sophisticated-looking plane resulted. However it would appear that this was another disappointing low-wing aeroplane. The longest distance flown being little more than that of the Mufli. Achievement of the HVS has been to operate in high winds; speeds greater than 21 mph (9.4 m/s) (the plane's cruising speed) have been quoted. (Aero Modeller, Aug 1983).
ADJUSTMENTS would have been difficult to make on the HVS. The "V" tail precludes adjustment of vertical or horizontal tail area; and the canopy fits pilots of only one height. On this plane, the pilot operated non-rotating pedals to drive an adjustable pitch propeller. The drive mechanism was complex, entailing cable runs to the pylon where there are chains to contra rotating flywheels on the prop-shaft. With a cantilever wing of 54 ft span and a carbon-fibre structure, the HVS first flew on 12th March 1983.
The HVS was designed and built before the setting of the Kremer World Speed Competition, yet its cruise speed of 21 mph was just in the range to make it a contender had it been more successful.
In 1980, Max Horlacher the head of a small company which worked with composites, hoped to build a plane which his son, then eleven, could fly and which could be entered for the Kremer figure eight competition. His first plane, Pelargos 1, did not take off, and although he blames this partly on the fact that his son had put on too much weight, he decided to call in assistance for his next design. Fritz Dubs, an aerodynamicist from Zurich who collaborated on the II pointed out that the aerofoil section must be changed to be suitable for the very low speed at which they intended to fly the new plane. The firm of Reichhold Chemie AG supported the project by supplying the synthetic materials used. It is noteworthy that the wing-ribs and other secondary structural items on this aircraft were made from carbon, compared with the more usual and cheaper foam sheet construction. Other unusual structural features were a rigid strut and a light rear-spar. This rear-spar, as well as stiffening the wing generally was also made to serve as a place on which to make the joint between the sheets of Mylar, the greatest available width being six feet, and the chord of the wing over eight feet. It might seem that the wing could have been covered by using the width spanwise, and forming the joints on ribs; but if "tensilised" Mylar was used then this would explain their procedure. Tensilised Mylar shrinks more in one direction than the other when warmed. If correctly oriented, it will provide a better approximation to the rib shape between the ribs.
The propeller was 12 feet in diameter, one of the largest used. For ease of construction, a rectangular shape was chosen for almost everything else. This aeroplane was one of the first to be easily transportable in sections. The constructors benefitted from Horlacher's business experience, and the lessons learned on the plane were, in turn, useful to the business, as well as an advertisement for them and for Reichhold. Once the Pelargos 2 was constructed, it was put on display at a trade show in March 1983, but did not make its first flight until seven months later, because of difficulties in finding a satisfactory transmission system. A Cardan type universal joint was one of the options considered for this.
On January 20th 1984 Horlacher wrote to the RAeS to enter for the Kremer figure eight competition. Max Horlacher knew that there was competition both from the HVS and from Rochelt's Musculair. He wrote "I do not grudge the German team its success up to now. Both the aeroplanes are distinctive. One could be curious which will be successful".
The Pelargos 2 first flew in December 1983. On a later flight it covered a distance of 1100 yards (1000 m). (See http://www.skytec-engineering.de/pelargos.htm).
MUSCULAIR I was built by Holger Rochelt and Gunter Rochelt, and designed by Gunter Rochelt, Ing. Ernst Schoberl and Dr.Ing. Heinz Eder. Gunter Rochelt had previously built a successful and radical solar-powered-aircraft. This human-powered-aeroplane was not built with the intention of winning a Kremer Prize. It was built with the intention of winning two Kremer Prizes. But it didn't. It won three of them! Although there are many difficulties in the design of an HPA, one of the ways in which it is easier than for most other classes of aeroplane is that one has generally needed to only consider a narrow speed range. But Ernst Schoberl in his optimisation process aimed to find a shape which would be suitable both for the figure-eight course and for the speed course (see next page), and it would be piloted by Holger Rochelt who was of only average athletic ability. As can be seen from the table, the wing area of 173 sq ft (16.5 m2) was one of the smallest used on an HPA, and contrasts with the 760 sq ft (70.6 m2) of the Condor, the only other plane to fly a figure eight. A conventional configuration was chosen, with the propeller behind the tail, the drive shaft being the length of the tail boom. This propeller had previously been used on the solar-powered-plane. Spar construction was by laying-up cloth onto a rectangular block of foam: firstly diagonal weave all round, then spanwise strips top and bottom. Ribs were foam sheet, and the wing was skinned at the nose area, then covered in Melinex. The torsional stiffness deriving from the box-spar and the Melinex covering was found to be insufficient and it was found necessary to involve the "C" shape nose skinning in the task of load-carrying. This was done by adding diagonally-braced carbon-fibre rovings and effectively changing the "C" to a "D", thus forming a closed box. The plane was built in three months and made its first flight, as yet without cockpit fairing, at the end of May 1984. Within two weeks, on 18th June 1984, Holger Rochelt made a figure-eight flight. One Kremer prize for the Rochelts, the second ever figure-eight in HPF.
Musculair I story continues later