Williams County Airport

Bryan, Ohio 43506

FLIGHT TESTING THE HP-11

Calculate your e.g. location and placard your HP-11 for maximum and minimum pilot weight to stay within permissible e.g. limits. The allowable e.g. travel is from 25% to 40% MAC.

If your loaded e.g. falls outside this range, carry sufficient ballast to bring the e.g. within limits.

Check the entire control system and attaching pins or bolts for cotter keys and all nuts and locknuts for tightness to insure that nothing can come apart or change setting.

Set control surfaces in neutral positions and ascertain that stick and rudder pedals are in neutral.

Move all controls, check for proper direction, extent and freedom of movement.

Operate flap to make certain that it works freely and does not bind when retracted.

Check tow releases for proper action.

Make sure canopy pins open and close freely.

Test flying a newly built sailplane is not a proper undertaking for a pilot with no experience in a sailplane so donít waste a lot of hard work by trying to fly your HP-11 if you don't have at least a private pilots license with a glider rating.

For the first flight, select a long sod field or wide runway free of closely set lights that could catch a wing tip. Most important, take off directly into the wind.

The flight should be an auto tow of only a few feet in height with release made in plenty of time to land straight ahead without danger of running out of field. With flap settings of 45 degrees or less the HP-11 will probably float farther than anything you have ever flown before.

The purpose of the first flight is to check control reactions and general flight "feel" without getting dangerously high. Flaps can be set at 30 degrees for this flight and left at this setting unless it is necessary to land quickly. Then, of course, full 90 degree deflection should be used.

The characteristics of flaps are considerably different than those of spoilers and different flight techniques are required. Below are points to remember.

1. Flaps increase lift, spoilers decrease lift. Hence, to maintain a constant altitude above the runway, the nose must be lowered with flap and raised with spoilers.

2. Flaps decrease landing speed, spoilers increase landing speed.

3. Small flap deflections will increase the "floating" tendency and may extend the distance covered before touchdown.

4. Large flap deflections increase drag tremendously and make steep angles of approach necessary to maintain flying speed.

5. Flap deflections increase the effective angle of attack of the wing and result in a stall at lower fuselage angle of attack.

6. Complete stall with full flap is approximately the same attitude as the "at rest'", position on the ground.

7. Then cranking in more flap during landing close to the ground, it will be necessary to push the stick forward to avoid "ballooning" due to the additional lift.

8. Always approach for landing at 65 mph. Maintain this speed while cranking flaps up or down to adjust your approach angle.

9. You can safely retract flaps at 65 mph to extend your flight if you get too low.

10. Never come in low and slow with large flap settings since you can do nothing to extend your glide if you get too low.

11. Full flap deflections provide, extremely high drag and steep approaches surpassing any other known type of drag brake I and, unlike most spoilers, they are very effective at low speeds.

12. If the HP-11 is floating down the runway and doesn't want to slow down, you just donít have enough flap cranked down.

After landing, always hold stick back during landing roll to keep tailwheel on ground for positive directional control. Pushing the stick forward can result in a ground loop, especially in high grass.

After the auto tow has been made and all reactions are normal, you are ready for an air tow.

Have the tow pilot briefed to maintain 60 to 65 mph. Use a towplane with sufficient power to climb decently and use an airfield sufficiently large so that you can got back in safely in case of a premature release. 3000 feet is considered a minimum height for an initial test flight air tow.

After release, practice using the flaps to familiarize yourself with their action.

Flight characteristics of the HP-11 are normal. No unusual habits have been noted. Control forces are lighter than most sailplanes with small deflections required for circling and most maneuvers. Stalls with a 200 lb. pilot are very gentle from both straight and circling flight. The ship will spin if it is kicked in with rudder and when stick is held back. Recovery is positive but at a slower rate than a Schweizer 1-23 or 1-26.

The HP-11 circles best in themals at 50 mph with 5 degrees of down flaps. If thermals are large, fly at 55 mph with 0 degree flap. Raise flaps to -5 degrees at speeds of 75 mph and above. Raising the flaps improves performance in two ways. First, it shifts the low drag bucket into the high speed range and second, the nose is raised so that the fuselage is better aligned with the air flow.

Make your first air tow landing well down the runway. Don't be afraid to use full flap when you want to get onto the ground. You might run out of runway if you donít.