pauldutt

I have several park fliers and I recently acquired a Norvel Glassair 400 motorized sailplane and I can't get it to fly right. It wants to bank right and spirals into the ground. If I simply launch it powerless off an embankment, it banks right into the ground within 50'. If I launch it under power, it climbs right and spirals (right). When I cut power, it continues to spiral right until it hits the ground. I can't get it to straighten out, let alone turn left.

The wings are perfectly balanced and square on the fuselage. The CG is 2 7\16" behind the leading edge. It has .5" U-D elevator travel and 1" L-R rudder travel. The wing does NOT appear to be twisted. I even temporarily added 15 sq. in. to the rudder surface but to no avail, Does anybody have any constructive suggestions?

I'd sure like to get in a good flight before I destroy it.

Paul

tkilwein

When you say the wings are balanced is that by CG and also holding the glider by nose and tail and see if one wing dips?
Is the rudder square to fuse and wings?
Possiblbly a slight twist in the wing or right wing is heavy provided surfaces are true, level and square.
Put glider-wing upside down and put two 3ft sticks on wing bottom, each side and make square(check a few places) and see
if sticks are parallel, no twists. Doesn't take much.
Just some ideas.

Tinkrerpilot

My Feedback: (2)

Check the horizontal sta for any twist also. Wings also for for twist like tkilwein mentions. Any good flat counter top will do. Check both the inboard and outboard panels. From the sounds of things you do have an alignment problem. Check all your flight controls to make sure they are all centered up as well. A few more ideas...

foodstick

I would set it on a table, walk back 10-15 feet and then squat down until you are looking straight at the nose of the plane..look at both the wings and see if one of the trailing edges of the wings is lower than the other, I am betting the left wing will have a lower trailing edge meaning either a warp or misalignment...

Tinkrerpilot

My Feedback: (2)

foodstick ,

From the sounds of the way he wrote the problem, I'm betting on a twisted wing too. I have never heard of the Glassairs having any really big problems like this one.

evan-RCU

Warped wing...

pauldutt

The sailplane is balanced sitting on a level table. It doesn't drop off in either direction. If I put a penny on either wing tip it will drop to that side. The rudder is vertical and aligned to the fuselage and the horizontal stab is correct too. I removed the wing and set it on a flat level table and neither side is twisted. The left wing side is perfectly flat (to the table) from wing root to tip. The right wing side has about 1/8" (max) raise in the center from the wing root to tip.

With the size and travel of the rudder, you'd think I could overcome a trim problem. My park fliers still fly good after numerous repairs by adding more trim. LOL

Paul

foodstick

you have to have the wing mounted on the fuselage to check the wings relation to each other...

pauldutt

I did all that. I sighted the wing from 15' etc and sighted down the wing from the tip. The wings looked fine. I took it off and laid it on a flat surface to see if would rock; it does not. The leading edge is straight from tip to tip. The wing is NOT warped, bent, or twisted. Like I said, the only thing I found was that the right wing panel was bowed about 1/8' max in the center of the panel.

I may have to experiment with a trim tab on the right wing to give it more lift since the plane doesn't have ailerons.

Thanks for your inputs.

Paul

Tinkrerpilot

My Feedback: (2)

Still think its in the wing. Lets try the wing on the table again. Starting from the center. Is the wing one piece or two pieces?
If one piece. Hold the center of the wing down on any flat surface. Check the L/E and T/E at the polyhedral break. This shoulb be flat or a little rise on the T/E. Then roll the wing up so that the poly joint is flat on the table with firm hand pressure adn the the L/E and T/E of the tip. This to should be flat or slightly raised on the on the T/E. Reverse this process forthe other half of the wing. Someething should show here. Possibly one or the other of the tips is twisted.

da Rock

A picture is worth.....................

The right wing in the attached has a warp that will roll the airplane counter clockwise. You can see how the white trailing edge warps downward. Especially if you compare it to the way the left wing's TE stays centered along it's length.

Airplanes don't roll unless something causes them to. The most probable cause is wing warp. Next cause could be a yaw to the right from the fin/rudder. If the fuselage is curved, or the wing not on square (from the planform view), the yaw would induce a roll from any wing that had dihedral. To get a clockwise roll, the left wing tip forward, right tip back would cause a roll. Yaw is easily seen since the plane usually turns in that direction. For lateral imbalance to cause the roll, it would take an obvious amount of weight to have such a significant effect.

Hope the picture helps.

JetCatJimmy

I once had a plane that looked perfect at glance but when flying would try to corkscrew. It turned out to be a stress fracture in the horiz stab. On the ground, it would look fine, but under load a small part would pull up forcing input into the plane. I was driving me crazy until I found it. A little CA injected through a pinhole solved the problem.

Hope you get this figured out!

pauldutt

I also found a break in the left horizontal stab about 1/3 the way out. I repaired that but it still spiraled in. Finally, I added a one by six inch trim tab to the TE near the end of the right wing and it doesn't look pretty but it flies ok. I did learn the sailplane is not as responsive as a park flier. You have to wait for a response after making inputs and the slower the plane flies, the quicker it responds.

I have seven successful flights so far.

Thanks for everyones help

Paul