6. Flight

Flight tests started from the middle of April. Other wise the aircraft would be destroyed by the crush against the water at the time of JIBR held on Lake Biwa. Therefore the official record flight was scheduled from June to the first week of July.(3)

The biggest problem of flight test was how to secure a wide space. We fortunately happened to find a suitable place. But it was far from our home. It took almost two hours to reach there and another two hours to carry the parts and assemble. So we selected to a sports ground near the Yoshikawa's house.

6.1 Flight Test

Trial flight test was conducted once every two weeks. On Sunday early morning, we tried on the soccer ground beside a river. The aircraft took off from plywood runway on the condition of which wind speed was below 2 to 3 m/s. Before the official record flight under FAI rule, we tried 13 trial flights and total flight duration was accumulated to 70 seconds

Fig10. Exercise of straight level flight

We concentrated on the training of horizontal level straight flight for the first month. The pilot should be used to continue the constant speed pedaling even if the aircraft changed speed and inclined. At that time two wing and two tail runners helped her to take off and control and also to get the feeling of a smooth climbing, descending and flight altitude.
On the next month she began the exercise to take off by her own power only with the help of wing runners but without tail ones.
At the begining she could not take off the aircraft. Even though she pulled the lever of the elevator when the aircraft was accelerated to take off speed, front gear did not come off from land after main gear did take off. It was clarified that it was caused by the reverse action of the elevator due to the lack of the stiffness of the tail boom. The problem was solved after pulling the tip of the tail boom to the tip of king post and the bottom of the cockpit frame with added brace wires.
The trial of the take off was conducted under the 2-3m/s head wind speed and the help of acceleration by runners in order to minimizing the exhaust of pilot and length of runway. It took 10m ground roll for take off, from 50 to 60m level flight of 1.5m altitude and 20m ground roll for landing. One cycle of the exercise required total distance of around 100m and 10 seconds. That was the limitation from the length of the play ground. There times a day was the limit from the view point of her physical strength.
It was difficult for her to detect the neutral position when a flying tail was applied. A great effort was required to pitching, because it was easily overcontrolled. The problem was solved by introducing self neutral system with trim.

Fig11. Trim adjusting mechanism

Weight of the aircraft was increased 2.0kg with dew in early morning. Small droplets stick to the wing upper surface near the leading edge. It is reported that airfoil DAE-11 is developed to achieve not only minimum friction and airfoil loss by minimizing profile loss due to transitional separation bubbles but also light weight and easiness of manufacturing.(2) But our experience showed that aerodynamic performance of wing was drastically decreased due to the disturbance of laminner boundary layer by dew. On the other hand, the characteristics of stall became blunt.(10) The training were sometime disturbed by the gloomy flight caused by large angle of attack due to increment of weight and decrement of aerodynamic characteristies.
Three different propellers were tested. Diameters are 2800mm, 3200mm and 3400mm. We could not keep required manufacturing accuracy and rigidity for one which is 3000mm diameter. Redesigned last one has comparatively small diameter of 2800mm, wider blade of maximum chord length of 320mm and smaller pitch. This is operated at comparatively higher rotational speed of 156rpm and estimated efficiency is 84.7%. It showed the best results because we could avoid fluctuation of rotation by pedaling with higher speed. Even if the estimated efficiency is 84.7%. It showed the best results because we could avoid fluctuation of rotation by pedaling with higher speed. Even if the estimated efficiency of other propeller was better than it, we could not achieve it.
Measurement of torque on the propeller shaft was tried by obtaining strain signal from wheatstone bridge though slip ring. But unfortunately we could not get a stable data because only 100m flight duration was far short to get them. We feel that it is neccesary to fly staibly as far as around 300m with altitude of 2 to 3m, in order to get those kind of actual flight date, to evaluate performance precisely and to use for farther adjustment of the aircraft.
Pilot could keep the constant rhythm of pedaling to keep smooth running of propeller by the help of pulse sound generator which was attached in the cockpit. Air speed was measured by electric current. Current was generated by 8cm diameter windmill which is attached on the top of arm from the cockpit.

6.2 Record flight

We challenged to the official record flight, twice. The key points for success are timing of the take off and how to climb.

6.2.1 The First Attempt
The first challenge was carried out on 6th June, two months after since the internal flight test began. The aircraft failed to clear 2m-altitude-line which is the FAI rule. The first attempt ended in a complete failure. At that time, we did not really know the answers to the proper power distribution at the start, accelerating condition and maneuvering timing of the elevator and how to climb. All the problems were unsolved. The flight test was tried fuiled.

6.2.2 The Second Attempt
Before challenging for second time, we studied and checked the records on the change of pedaling speed, power distribution, running distance and running speed during ground run.
The followings are improved for the second time.

1)Pedaling Speed :

The speed rises to maximum speed a few seconds after since the pedaling begin. Then the speed can be maintained for a few seconds. It is shown in figure12.
Rotation Rate :
The speed rises to maximum speed a few seconds after Since the pedaling begin. Then the speed can be maintained for a few seconds. It is shown in fig12.

Fig12. Trend of output, rotation rate and torque on full-power pedaling (11)

Rotation Rate :
The speed rises to maximum rat a few seconds after the pedaling begin. Then the rate is maintained for a few seconds.
Torque :
Torque is found to be maximum just after pedaling begins, and gradually decreases.
The above facts clearly shows that anaerobics power becomes maximum in 3 seconds after the beginning of pedaling and gradully decreases due to the fatique in case of full-power pedaling. We examined the optimum combination between pedaling speed, gear ration, ground run, and power distribution in order to achieve enough speed for take-off.

We finally came to the answer as follows.

1.Full power pedaling time : 5 seconds
2.Pedaling : 3 revolutions
3.Running Distance : 20m
4.Maximum Speed : 5.5m/sec

2) Determination of take-off Condition

As take-off speed of our aircraft is determined to be 6.5m/sec, shortage of speed requires the moderate head wind condition of 2 to 3 m/s like in the test flight.
The examination result shows that there will be some remaining power which can keep enough rotating speed to climb for at least 4 to 5 seconds, if it takes off at 20 m ground rolling.

Fig13. Flight plan

The climbing up to 2m should be done in the time. Climbing is separated into three steps. The rate of it is limited to 0.8m for distance of every 10m in order to minimize the speed loss. The aircraft should keep 2.4m above the ground at 30m after the take-off. It is 10m before the 2m-altitude line check point. Now it is the last chance to make correction of the flight course and to decide if it keeps on going or it should be stopped at the check point.
On the 5th of July, 1992, she finally became the first Japanese woman to fly a HPA successfully in singing a small bird in the morning mist at Fujigawa soaring-port, in the presence of a official witness that admit Japan Aeronautic Association.

1.Straight flying distance : 119.045m
2.Duration : 22.98secnds
3.Pilot : Kotono Hori
4.Aircraft : HYPER-CHick"KoToNo Limited"
[ Approved by Japan Aeronautic Association ]

Fig14. Record flight

The moment of flying over 2m-altitude line
I would like to add that the pilot decided to have her long hair, used to be down to her waist, cut short to lighten herself just before the second attempt and we made our dream real.

6.3 The 17th Japan International Birdman Rally

On the 1st of August, 1992, one month after since the record flight, we participated in the 17th JIBR.(11) In the one month, we finished six flights to adjust the conditions for the JIBR.(11) On the day of the rally, the climate rarely stays moderate and unexpected wind blows every year. Wind of 4 to 5 m/s blows and the same direction never states. To deal with the strong wind, the angle of attack for the wing was decreased to the limit, which should not promise a good flight in a normal condition, and we planned to use a height of the 10m for start, imaging a smooth gliding aircraft with power.

Fig15.The 17th Japan International Birdman Rally