An association between Lippisch and Dr. Martin Brustmann which was to
continue for many years appears to have formed at this time. Brustmann in the
1920s carried out studies into the power outputs of humans, based or. hia
experience IS an expert on xedical matters, specifically physiology, related
to sport. He prcduccd figures on the short duration power outputs of athletes,
stating that a man could produce up to 1.5 kK in a very short burst.'reducing
to a continuous output of 0.19 kW.
Brustntann proposed means for utilising as many as possible of the muscles
in the body, the total weight of muscle being used amounting to approximately
25 per cent of the total body weight. Brustmann suggested using the arm and
chest muscles, in conjunction with the main leg muscles, in a combination of
arm movement and the oarsman's roller sliding seat. (It is of interest to
note here that Everling, writing in 1934, describes how he applied for a
patent, in conjunction with Erich Offermann, in 1924. This patent was not
granted, but the invention he described was an extension of the ideas put-
forward by Brustmann. The main feature of the design was a means for over-
coming the severe shift in the position of the centre of gravity which is
associated with a sliding seat. Such movements would of course be unacceptable in an aircraft, as the pilot would be continuously compensating, using the controls, for the resulting pitch angle changes.
Various claims were made for the total power generating capability of a
man using such a combination of muscles. Everling believed that 1.9 kW would
be achieved momentarily by a trained oarsman, but Brustmann is reported to
have quoted a figure 5.3 kW being attainable for periods of less than ten
seconds. This remains the highest value claimed for human power output in
the context of man-powered flight.)
A few years later Brustmann, aided by Lippisch, constructed an ornithopter
with a wing span of about 10 metres and an empty weight of 30 kg. A young
athlete, who was also a pilot, Hans Werner, carried out the first flight
trials, which were performed on a downward incline (Fig. 49). After several
attempts, a flight of about three-hundred metres'was reported to have been
achieved. In this distance, eleven flappings of the wing were carried out.
It is doubtful whether such exertions extended what was in fact a glide.
I.ippisch, in criticising the machine, complains of the inadequacy of the
transmission (this being via cables running over pulleys), but heralds the
fact that it flew. Following these early attempts, Brustmann took his aircraft
to Berlin to give demonstrations. However, he attached a large undercarriage
to the fuselage, with the result that the machine was unable to take off!
I.ippisch then appears to have attempted to further his work alone. In the
summer of 1933 he carried out experiments on wings for man-powered aircraft,
but his tests were cut short by his enforced transfer to another research
establishment at Darmstadt.
Brustmann Schwingen fIugzeug.
In 1924-25, the leading personalities on the Wasserkuppe began to extend flight research to other types of flight. In the Rhön tenders at that time, corresponding prices were already offered for services of other types of flight. The results at that time were naturally quite sparse, since this difficult problem was very difficult to solve. In certain circles, there was talk of a standstill in gliding movements and the hopelessness of such research work. Among the applicants registered in 1925 was Dr. Martin Brustmann with a winged aircraft. Despite the daunting attempts during the competition, Brustmann did not give up his work and made a jump of 15-20 m
4 days after the competition. A small ray of hope !
But still there was no progress. At first, lack of money interrupted the experiments, until in 1928 he was able to order a gliding fuselage monoplane with movable wings. Construction Alexander-Lippisch, construction A. Schleicher, Poppenhausen.
The aircraft, which weighs only 70 kg and has a wingspan of 10 m2, has an area of 12 m2, no use, normal altitude and side control connected to a stick. The wing precipitation occurs by stretching the legs, the force is transmitted by cable pulls and rollers to a Durai tube triangle, which engages at the center of pressure of the wing. The aircraft performs gliding flights of 6-10 sec. duration at 8-10 sec/m speed on the plane with rope start. Under swing beat, the distance
achieved in gliding flight is extended by up to twice as much, and the flight speed is increased to 12-15 sec/m. The effort required to fly wings is about the same as in racing rowing. The aircraft was flown in by Hans Werner Krause and Fritz Stamer on the Wasserkuppe. Krause has already performed over 60 successful swing flights with it.
In order to promote swing flying, it would be desirable if the RhÖn-Rossitten-Gesellschaft would once again advertise prizes in a competition for "aircraft powered by human power", which are to extend their gliding flight distance by a certain percentage by human power.
