Gap Seals

[Micro Mong Bldr]

Just how critical are the wing to fuselage gap seals? I don't have much of a setup there, have been taping over the gap.

Thanks,

larry

[Dorsal]

Never did mine though I think about it sometimes

[HighWing]

Are you talking about the gap between the #1 rib and the butt rib? I read an article once about wing root fairings. Definitely not the issue, but if the junction between the wing and fuselage on a high performance low wing is left a sharp 90° it creates significant drag. I mention this because the Lancair IV I helped with is faired nicely, but since the wings are removable, there is about a 1/8" gap between wing root and wing. The owner tapes over the gap with vinyl tape - we're talking 200 kts. Since in both instances we are talking about the top of the wing - the most critical wing surface, I would suspect if there is a gap, it would produce some drag as the low pressure on top of the wing sucks cabin air out disturbing the airflow.

With the original style Lexan windshield, the plastic can be cut to overlap the gap. That is what I did.

[Av8r3400]

The original Whitman designs have nothing but square corners and they put the fast glass to shame often...

I saw a local Tailwind absolutely embarrass another local retractable Lancair. Both with o320 150 hp motors.

[jiott]

I overlapped the acrylic windshield/skylight just enough to seal the gap. Very easy to do.

I wish someone would come up with an EASY, GOOD LOOKING, EFFECTIVE gap seal for the elevator to horizontal stabilizer.

Jim

[HighWing]

I did exactly that. Definitely NOT EASY, but the looks seem OK and I have no problem three pointing. Two out of three is not bad. I must say though, the rudder and vertical is much easier given the room created by the rod end hinge. You can see what needs to be done with the smaller radius created by the tube hinges.

One ply fiberglass shapes with foam ribs for light weight.

Elev Gap seal 1.jpg

Not quite closed at max deflection down or up. Note fillet fairing between horizontal and vertical stabilizer surfaces.

Elev Gap Seal 2.jpg

Desert Fox Fly-in

Kitfox Touch.jpg

[kmach]

Hi Lowell ,

Looks real nice, patent pending ? LOL

How do you get at the hinge bolts for lube and inspection ?

Are there covered accesses on the underside ?

[mr bill]

I got the idea from American Champion Aircraft (Decathalons etc) who welds in an extra piece of steel tubing to form a gap seal. I bonded on pieces of wood, leaving gaps for inserting the hinge pins later.

[dginok]

Here's a nugget I came across the other day:
http://store.cubcrafters.com/Gap-Sea...SA_p_1296.html

[HighWing]

How do you get at the hinge bolts for lube and inspection ?

Are there covered accesses on the underside ?

No covered access. I use a goose neck LED flashlight to inspect them through the gap on top and LPS 1 with the spray tube for lube. Actually the hinge pins are continuous - two long hinge pins. I made them of 1/8" carbon fiber rod with SS tube bushings Hysoled in place for the bearing surfaces. They are retained in the center with sleeves and cotter pins. It is definitely a must see before every flight as it deviates from the norm.

The image is a drawing of what I did in my first Model IV, using quarter inch foam sanded to shape and then covered with a light weight glass cloth. This time I made molds and vacuum formed the fiberglass shapes I needed. I guess I should say here that I had 900 hours on this set-up with no issues.

Gap Seal X Section.jpg

The first design. There were cut outs under the horizontal for hinge maintenance.

horizgapseal1.jpg