Sunday, 16 January 2006

Pasadena, CA

Flight Test: The Sky Rider

Test flights of the Sky Rider were performed by three flight test personnel at Flight Test Site A, aka “Beckman Field”. The aircraft was randomly hand-launched from person to person. The flight path could be varied easily by aiming high, aiming low, throwing hard or lightly. Depending on wind direction, the flight range could be as far as 100 feet. Flight speed also varied with wind direction, but usually was slow enough for ground crews to catch the plane in mid-air.

Being made of foam, the Sky Rider is extremely light and easy to handle, but highly vulnerable to gusts and headwinds. Usually it lands smoothly, but occasionally will crash nose-first into the ground. So long as flights are conducted on soft ground like grass then damage is confined to scuff marks and minor loosening of the wings.

Flight Test: The A7 Tornado

Three Test flights of the A7 Tornado were performed by two flight test personnel, also at the “Beckman Field” site. The A7 has no landing gear and so was hand-launched from a standing position. The flight test crew consisted of a Flight Controller and a Launch Specialist.

Test Flight 1 was hand-launched due South from the North end of the field from the top of a 5′ retaining wall. The throttle was held at full for the duration of the flight. The flight began erratically followed by a wild swerve to the Northwest. Attempts by the Flight Controller to correct the flight path failed. The aircraft collided at full speed with Obstruction A (a telephone pole). The collision sheared off the left wing. The aircraft and detached wing continued on separate paths out of the test flight area and across the street bordering West side of the test site. The aircraft came to a rest at Crash Site 1a, and the wing debris at Crash Site 1b.

A passing automobile very nearly missed the debris field of Crash Site 1a before the retrieval crew arrived, but no further damage was inflicted on the aircraft parts. It was found that the nose of the aircraft was cracked and slightly crushed on the left side. The left wing was retrieved from Crash Site 1b. It had detached relatively cleanly, breaking only around the point of the mounting screw and leaving the broken edge of the wing on part of the adheseive tape. On the aft edge of the point where the wing mounts to the fuselage there was still about 3″ to 4″ of bare adhesive tape. The wing could be reattached at this edge, with the fore edge hanging only slightly loose. The battery pack and power switch, both located in the nose, were both still intact. Although there were spare wings include with the A7 retail kit, they were not present at the test flight. After serious discussion the flight crew decided to attempt a second test flight with the left wing slightly loose.

Test Flight 2 was also hand-launched due South from the North retaining wall. The throttle was held at full for the duration of the flight. As the aircraft approached the Southern edge of the field, the Flight Controller made attempts to turn the aircraft left for a heading due East. The aircraft did not respond until after reaching the parking lot bordering the South end of the field, but finally turned due East. As the aircraft approached the Southeast corner of the test site, all attempts to turn North failed. The aircraft continued into the area South of the building bordering the East side of the field. At this time the Flight Controller released the throttle and visual contact with the aircraft was lost. The aircraft came to rest at Crash Site 2, from which it was retrieved by the Launch Specialist.

After the aircraft was retrieved, it was discovered to be in much the same condition as it was after being found at Crash Site 1. The left wing had also become detached again. After serious discussion the flight crew decided to reattach the wing and attempt a third test flight.

Test Flight 3 was hand-launched toward the Northwest from a standing position at the Southeast corner of the field. The throttle was held at full for the duration of the flight. After a slightly erratic launch, the aircraft unexpectedly turned right toward the Northeast. The Flight Controller made unsuccessful attempts to turn the aircraft back toward the West and away from Obstacle B (the Beckman Institute building) bordering the East edge of the field. At a distance of about 10 to 15 feet before collision with the building, the aircraft veered to the left and Northward. After further unsuccessful attempts by the Flight Controller to steer the aircraft back over the field, it finally collided with the inside edge of a window on the third floor. The aircraft came to a halt at Crash Site 3 on the sill of the window.

It was observed that upon impact with the building, the left wing had once again become detached and rested next to the aircraft. Several attempts were made to fly the disabled aircraft off of the ledge under its own power, but the onboard batteries were approaching full discharge, as could be audibly detected from the diminishing sound of the A7’s motor. After 15 to 20 minutes of waiting a final attempt was made by the Launch Specialist to dislodge the plane. With just enough thrust to push it over the ledge, the aircraft fell 3 storeys and landed nose-first onto the bare pavement below. The detached left wing remained on the window ledge. It is believed that this is the time that most of the final nose damage occurred.

After a careful safety inspection, it was deemed that without both its wings the A7 was no longer airworthy. Several attempts were made to lash together the Sky Rider and the A7 with tape. The power to weight ratio was plainly too low and the attempts were not met with any success. Flights tests of the A7 were declared completed.

Flight Test: The Cessna 180

One test flight of the Cessna 180 was conducted during a midnight expedition to Flight Test Site B, aka “Morrisroe Field”. Wind was from the Southwest and was approximately 10 to 15 mph and increasing, with strong gusts. The ground crew consisted of a Flight Controller and a Launch Specialist. Visibility was low due to darkness, but the electric lighting was moderate and sufficient to see all the way across the test field.

An attempt was made first at a runway launch, but the combination of wind, rough terrain, and very small wheels caused the aircraft to veer wildly whenever the tail lifted from the ground. The subsequent hand-launch to the Southwest was successful and the resulting flight lasted for several seconds. Again, the combination of strong winds and small size of the aircraft caused a significant reduction in degree of control of the plane.

During the flight, once the flight path had been stabilized, a controlled turn downwind resulted in a rapid drop in altitude. A quick turn to the right (Northwest) caused a rapid increase in altitude. An attempt to level out the path of the aircraft caused several more rapid altitude changes. At that point the Flight Controller determined that the aircraft should be brought to a landing as soon as possible to reduce the risk of complete loss of control of the plane which could result in damage. From a height of approximately 20 feet the aircraft was then allowed to slowly lose altitude, but a gust of wind caught it and quickly slammed it noe-first into the turf. The plane was retrieved and close inspection revealed that a blade from the propeller had been broken off on impact.

At this time it was determined that without both propeller blades the Cessna was no longer airworthy. In light of that, the the rising wind, and the late hour, the test flights were halted.

Conclusions

In short, all the test flights were considered successful. Each of the aircraft tested was airborne either under its own power or for more than 1 cumulative minute. Although these are not official criteria for success, the 3 aircraft represented 3 types of flight method and control; the glider had no control other than initial direction and velocity, the A7 had minimal direction control, and the Cessna had moderate direction control. Each flight test revealed important aspects of flight control for each type. From each of these aspects of control and the results of their testing come several key points:

• Flight test areas should be large and clear of obstacles.
• Spare aircraft parts and repair equipment should be located at the test site during flight tests.
• Flight tests should not be conducted in windy conditions (unless wind is part of the test).
• More liberal application of velocity control should be used to control altitude.
• A flight test should be terminated (i.e. reduce motor power to zero) as soon as danger to the surrounding terrain or personnel is deemed imminent.
• At all times, in relation to the site and flight crew, test aircraft should be considered expendable.

Repairs to current damage will be made in the lab. Additional spare parts, tools, and equipment for repair and building will be acquired. Testing an aircraft with aileron control surfaces will complete the basic flight test program. Planning and scheduling is in progress.