Gap Seals

[Keith Mackey]

My airplane is a 55 model and when I got it, it still had the original fabric. All control surfaces had fabric gap seals which would have made it impossible to remove a control surface without cutting this fabric strip. There were no seals on the flaps. I assumed all Mites were manufactured this way until Dave posted a picture of Harry Mitchell's N4105 taken in January 1958.
http://www.mooneymite.com/articles-individualmites/first.two.weeks.mitchell.htm

The paint design on the fabric appears to be original and the ailerons had no fabric gap seals like mine. I contacted Harry and he stated "My Mite was a '53 model and I doubt that any changes had been made to it." I'd been copying Dave with this info and he posed the question to Bill Wheat who was a long time Mooney Customer Support employee. Here is Bill's response:

"If there were gap seals on any Mites other than the 1955 models and the M19 I never saw them. The intent was to decrease drag to improve performance but there was never a performance baseline established without them and then added them to do another for comparison. None of us could tell that they were worthwhile. Because of the hinge movement of the flaps it was impractical to try them there. I have flown the 1955 models with seals and the others without seals and can tell no difference in cross wind handling. They both work very well. Of course I feel that cross wind abilities are far more dependant on Pilotage than on the aircraft, granting that low wing aircraft have an advantage over high wing aircraft."

I'm starting this thread to archive this valuable info and make it available to the Mite community, but would also welcome any additional info others could add. It would be interesting to know which Mites have or do not have gap seals and to hear pros and cons from those pilots who fly in either configuration.

[Glenn]

Gap seals rule. You'll notice the difference at the low end. Better roll response and the tail stall buffet occurs at a much lower indicated. My old -55 Mite has the fabric seals. Yes, it is a bitch if you want to remove a control surface.

I'm certain the yaw would be better at lower speeds, too. Never gave it much thought because all Mooney's suck when it comes to rudder, so I thought. I remember landing on one wheel nearly dragging my tip at PDX in a 20kt x-wind. I was indicating 100 mph when I touched down just to maintain runway heading. It was fun watching and listening to the heavy captain whine about chaning runways. Only done when the wind exceeds 20kts because of noise issues. Fortunately they changed to the x-wind runway when I departed. I was at 500' just a short distance from the threshold when I turned downwind for home. Never made it back so fast, ever!

Mal Gross made a startling discovery when he restored his Mite. Apparently the factory just welded on fixed rudder stops and never trimmed or adjusted them. He brought a template to Porterville and found that vertually all the Mites there were missing several degrees of rudder travel including mine. Mal flew out of Orcas Island where almost every landing is a x-wind. He said that extra couple of degrees made the difference between landing at Orcas or having to go to an alternate.

[Joelj]

My Mite is painted white and I was able to source some vinyl tape that is about 4 inches wide and typically used to seal the seams on blanket insulation used in pole buildings. This tape is pretty much an exact color match to my airplane and I have installed it on my aileron gaps with good results. You can also remove the tape if you have to - it typically leaves adhesive residue behind, but that cleans up with some gasoline and a rag. You need to apply it with the aileron in the down position to allow enough slack for movement. It would probably work well on the elevators, too, although I haven't applied it there.
Joel

[richardrank]

When Tony Terrino restored 118C many years ago, he put on metal gap seals. When I re-restored it, I read somewhere that gap seals may decrease drag slightly, but they also slightly reduce aileron control at low speeds. Dick Rank

[Patrick Moran]

It was interesting reading the comments regarding aileron gap seals and performance.

When I first test flew 9AW after a refurbuishment (not airworthy upon purchase) I had applied duct tape for temporary seals (as suggested by the supervising AI). During one test hop the tape peeled off the right aileron. I discovered it when the right wing took a precipitious drop. It required nearly full opposite aileron to level the wings. Fortunately I was in the pattern at the time. I applied the permanent fabric seals prior to the next flight!

My experience is that the gap seals make a sigfigant difference. I cannot imagine operating the Mite without 'em.

phm

[richardrank]

Surely, any difference in left and right wing configuration will affect flight characteristics, especially trim. Aero engineers say that gap seals on flaps and ailerons will increase speed to some extent, but they also decrease desired effectiveness of flap and aileron deflection. Dick Rank

[Glenn]

I did extensive before and after test flights to a C-170 that I restored in the early 80's. I'm not a fan of engine mods. The added weight generally messes up an otherwise doclie airplane. I added a heavy 220 hp Franklin with a big ol'seaplane cs prop. Took a 25 amp battery off the firewall and stuck a 35 amp battery in the tail. A stiff C-180 gear that actually moved the axle forward a couple of inches. The result was outstanding. The planes performance was superior to the M4 Maule that the engine came from. Shorter take off and landing and a significant cruise increae compared to the Maule. Never looked at a Maule again. It was easier handle on the ground during takeoff and landing. I'm guessing that was a result of the new gear. The 170 was actually much more easier and enjoyable to fly modified than stock.

Last thing I did was to install gap seals. Flaps went in first. Cleaner look on the ground. No noticable change in cruise. Increase in stall speed at full flap. Suggest that the gap seal was a waste of money.

Next the aileron seal. Not very big. Didn't expect much. No difference in cruise, but the low end was the difference between and day. Fly a Cessna at minimum controllable airspeed and roll the ailerons stop to stop and see what happens. Not very much. With the gap seals the roll rate at minimum airspeed was unbelievable.

I know Mite owners are more concerned about speed. My guess is that the biggest difference is going to be in flight control response which would be like going from a champ to a P-51. Who wouldn't want that?!! There will also be a substantial reduction in low end buffeting and reduced stall speeds.

Like I said in an earlier post: Gap seals rule.