LSA Quickbuild First Flight

[Collin Campbell]

Shimming the aileron mounts is a very effective way to trim for a heavy wing. A left turning tendency can be cured by adding
washers under the TOP aileron hinge mounts on the left wing spar. This in effect "lowers" the aileron in relation to the wing, causing it to produce slightly more lift. A high aileron equals a "heavy" wing. If this doesn't completely correct the situation, you can additionally add washers under the BOTTOM of the right wing.

Collin

[Mark Goldberg]

This is what I had to do on my 4 place. Use AN970 wide area washers. Mark

[bway]

This is great info that I would not have thought of. Thanks much. Bob

[bway]

I decided to do some testing to see what effect power and speed have on my slightly heavy left wing. What I found was that it is much more power related than speed related. With the power at idle and the ball carefully centered, there is really no heaviness of the wing, pretty much regardless of the speed, it seems. The air was not perfectly smooth, so I will test again, but I think that means the airplane is built straight. I would not have thought that torque/p-factor would have been significant at higher speeds, but it apparently is. I plan to trim to neutral at normal cruise speed and power though. More to come. Bob

[stinger]

Thanks for the input Bob. Tell Rusty hello. Stinger

[bway]

Because the slightly heavy left wing seems to be power related, I'm wondering if the engine just needs to be canted right slightly. Has anyone tried this on any of Bobs designs? Pretty much all of the production airplanes I've owned used this technique. Bob

[Mark Goldberg]

I just spoke with Bob Barrows and read to him your comments about the wing heaviness. To him, it sounds like a vert stab or rudder issue rather than any wing issue. He suggests that the next time at cruise speed/power when the wing gets a little heavy - try to pick it up using ONLY rudder. If this works with just a little rudder pressure - then the solution is to use a little tighter spring tension on your right side rudder pedal (for left wing heaviness). Of course this will slightly affect things at other airspeeds. You might have to lightly touch the LEFT rudder to keep the ball centered at lower speeds. Mark

[bway]

I plan to call Bob about this slightly heavy wing issue and give him more complete information. I flew last Friday and climbed up to smooth air where I verified that at high cruise (115 mph, or so) using right rudder to hold the wings level results in a slow skidding turn to the right with the ball displaced one full diameter to the left. At low cruise (100 mph or so) the same thing happens but the ball is only displaced about 1/2 a diameter. When gliding at about 100 mph, there is really no wing heaviness. If I hold the wings level at low cruise with the ailerons, the ball is pretty much centered with no rudder required. At high cruise, very slight left rudder keeps the ball centered while holding wings level with the ailerons. I think the first solution (lower the left aileron slightly) may be the entire answer, but I do wonder about canting the engine a bit. More to come. Bob

[bway]

If this works for me, a picture of my airplane should be attached. If not, I'll need someone to tell me how to do it using my iPad. Bob

[bway]

Lesson learned. .063 spacers under the top pads of the left aileron did the trick. My heavy left wing is now completely cured and the airplane flies straight and level hands off. After talking to Bob Barrows, I was pretty sure lowering the left aileron would be the solution, but after seeing that the difference was almost imperceptible, visually, I did wonder how such a small change could make much difference, but it did. I also found that the airplane is much easier for me to get trimmed for cruise with the heavy wing fixed. Apparently, I was either pulling back or pushing forward slightly while holding the wing up. All I said before about how well the airplane flys goes double now. Trim is very sensitive to power changes, though. Even a 25 rpm, or so, increase from leaning requires a trim adjustment. More down thrust would probably help that, but hurt performance. I prefer the performance, so it will stay "as is", and I'll trim as necessary.

I have been been trying to think my way through how it is that such a tiny adjustment of the aileron could have so much effect. I think I may have the answer. When the wing was heavy, I noticed that when I was holding the wing up, the trailing edge of each wing was even with the trailing edge of each aileron. However, if I released the stick, the ailerons were displaced about the amount you would expect at the trailing edges; the trailing edge of the left aileron was up, and the right was down. The hinge points on the ailerons are quite a bit back from the aileron leading edge. I believe that lowering the aileron even that nearly imperceptible amount exposed the left aileron leading edge to more air flow forcing it up, and forcing the trailing edge down. Now the trailing edge of each aileron is even with the wing trailing edge "hands off".

My friend, technical advisor, and A & P, Rusty, a very experienced pilot finally got to fly the plane and pronounced it good. He has a lot of experience with experimentals, so I was very pleased. I wanted him to fly it sooner, but because of the holidays, we could not get the insurance changed to cover him until a few days ago. The airplane now has 19.6 hours on it and I hope he will help me fly the rest of the 40 hours off. We can share the fun, and I value the knowledge he brings.

Next time out, I plan to start really checking out the spin characteristics. I'll work up gradually from a half turn, until I get to at least six turns as it takes that many turns to fully develop the spin, in my experience. I do not expect any problems, but I'll borrow a chute anyway.

More to come, Bob

[Mark Goldberg]

Sounds good that your heavy wing fix was that simple.

You will be the first to check spin behavior in the LSA. Bob's other planes have all done spins, and they recover conventionally. They do wind up pretty quick however. Be careful after recovering from the spin that you do not let your speed build beyond VNE in a spiral. Without the counterweights on the tailsurfaces and ailerons, if speed built up too high you could get flutter.

I know you are a more experienced pilot than me Bob, but just wanted to throw out a little caution. Mark

[bway]

Point well taken, Mark. My plan will be to work up to 6 turns one turn at a time. If I start to exceed 130 mph in the recovery, I will simply stop and be satisfied at the number of turns reached. I have taken the airplane to 133 mph with no issue so far, but I want to have a perfectly calm day for taking it to the red line and for spins. Thanks for the concern. Bob

[Bcone1381]

Marks comment brought a smile to my face and some fond memories you might enjoy.

Back in the 1980's I was a Freshman in college, a Private Pilot, cocky and confident, with maybe about 80-100 hours. I had done spins with an instructor once, so one day when I was out flying decided to try a one turn spin on my own in a C-150. I lined up on an East/West road, and attempted to exercise my good airmanship. The entry, spin, and stopping of the spin all went as it should. During the nose down recovery, the speed started to build and I applied a little too much back pressure on the yoke. As I was coming out the bottom of the recovery with the nose rising, things under control, and I was feeling the G force. Well, it must have been a bit excessive because I noticed my peripheral vision started narrowing like I was looking through a pair of binoculars. It continued to narrow the point where I could see two separate but perfect circles of the view out the front window. I remember being as calm as can be, thinking "Okay, Brooksie, just trim out this old girl real nice and you'll probably be okay if you loose consciousness." The vision then immediately recovered in two shakes of a Lambs Leg. Then I thought to myself "maybe its time to go back and call it quits.....wait a minute. If I do that I might really scare myself and never feel comfortable again." So I climbed back up to 5000' and did another one. That recovery went textbook. I always enjoyed spinning the C-150 and later in my flight instructing career was looked to by others when Flight Instructor candidates required spin training.

Brooks Cone

[bway]

Yes, Brooks, I have experienced the same thing in the Texas t/w 150 hp Cessna 152 Aerobat I used to own. In my case, it was not a spin, but a botched aerobatic maneuver I was trying to learn. When I was instructing, I always thought thought that the C-150 & C-152 were great airplanes for teaching students to be respectful, but not afraid of spins. They were also great for teaching students the importance of being coordinated on departures and approaches because stalls out of those could be practiced at altitude safely. Students could safely learn that a stall with bottom rudder will quickly roll the airplane inverted, and into a spin. They could also learn that stalls out of slips are much easier to manage as the airplane rolls over the top. Even though I only instructed for a couple of years while I was in college in the 1960's, I have fond memories of those days. I thought it was a mistake when the importance of spin training was later de-emphasized. I have flown with a lot of later generation pilots who have a tendency to skid a bit around the turn to final and I think part of that is because they have never actually experienced just how quickly an airplane can roll inverted out of an approach stall. Bob

[bway]

This is a photo of my interior with gray latex paint on the interior of the fabric. It actually matches the tubing better than it appears to in the photo. I meant to post this earlier, but forgot.

[DRLPatrol]

.... Trim is very sensitive to power changes, though. Even a 25 rpm, or so, increase from leaning requires a trim adjustment. More down thrust would probably help that, but hurt performance. I prefer the performance, so it will stay "as is", and I'll trim as necessary.....

I thought I had read that the Bearhawks trim was more of a set and forget deal. Just set for load. Is this something just for the LSA or did I read something wrong. Probably the latter.

Doug

[JimParker256]

I thought I had read that the Bearhawks trim was more of a set and forget deal. Just set for load. Is this something just for the LSA or did I read something wrong. Probably the latter.

Doug

I read the same thing, but I'm pretty sure it was talking about the Patrol, and not the LSA.

[bway]

Working on operating handbook items and electronics, mostly, now. About 27 hours total time now. I'm trying to attach a takeoff movie; I hope it works. I continue to be very pleased with performance an how easy this airplane is to fly. Landings are extremely easy; I can usually touch the tail wheel first while the mains are about 6 inches off and the soft gear just settles the plane with no tendency to bounce. Very well designed. Bob

Unfortunately, the short movie taken with a friends iPhone 4 would not upload. I guess it is not an allowed file type.