HP-18 Center Stick Project

Update 9 July 2001:

I test flew my HP-18 with the center stick installed on Saturday, 7 July 2001 at Air Sailing gliderport. The flight lasted about an hour and twenty minutes, and demonstrated that the new control system worked as expected and did not introduce any bad habits into the aircraft behavior. The flight was conducted at a calculated CG position of 32.7% MAC at a total calculated weight of 697 lbs.

The aircraft was inspected by both an A&P mechanic and by an FAA official from the Reno FSDO the day before the first flight. The A&P looked at it for its annual condition inspection, and the FAA guy looked at it so he could reissue its airworthiness certificate with a new set of operating limitations and a 5-hour test period. No discrepancies were noted in either inspection.

The flight started with a normal takeoff and a 4600' agl (8900' msl) tow. I used -4 degrees of flap on the initial roll, and cranked over to +10 degrees after the tail came up. An initial wing drop from the towplane wake was easily countered with aileron.

Off tow, I first performed incipient and full stalls, straight and turning, at three flap settings, and also explored general aircraft behavior at flap settings from 0 to 90 degrees.

Satisfied that the aircraft behaved well enough to allow a safe landing, I retracted the landing gear and indulged in some general soaring flight to get a better feel for the aircraft. Problems with the vario display and with the TE compensation precluded any serious thermalling, and problems with the radio hampered communication with the ground. However, I did get up to about 13000 feet, and managed to perform several inter-thermal runs to explore the upper-middle part of the speed range.

At the end of the flight, I circled down over the airport with about 45 degrees of flap, and then performed a normal left-hand pattern and landing to runway 3.

Some impressions about the flight:

The next few flights will further validate the control system and other aircraft systems. If those flights go reasonably well, I hope to finish off the test period, and then (in the finest HP tradition) compete in the Air Sailing Sports Class Contest.

page updated 07/09/01 all text and graphics copyright (c) 2001 HP Aircraft, LLC