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.

5446

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

5447

Desert Fox Fly-in

5448

[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-Seal-Kit-for-Experimental-and-LSA_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.

5453

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

5454

[Slyfox]

just take some tape and put the stickside against each though the lenth that you are going to use. leave about 1/4 inch on each side. now put it through the opening, seal it on top on one surface and than put to the other sealing surface and seal it down. kind of hard to explain. but u end up with sticking on the horizonal on the top side and sticking to the elevator on the bottom side. I use packaging tape clear and than paint with spray white afterward. I suppose you can look for tape that's close to your color and do the same. one more thing, put the elevator in one of it's throws so it doesn't bind when done.

[SkyPirate]

If your going to use tape, full down elevator, put tape on top, the full elevator up, put tape on bottom :) doing this the 2 tape strips wont meet in the middle unless you cut lengths to go between hinges and actually push it down with a paint stick or something similar

[SkySteve]

The last time I put tape on my elevator to gap seal, I found Duct brand has a clear tape, which I used. It is a heavier tape than packing tape and has been on my plane for over 3 years so far. I found it in the aviation department of Home Depot.

[Slyfox]

if you use the packaging tape there is bad and good. I use the scotch brand.

[Dorsal]

This thread seems to have drifted from the OP and wing to fuselage gap. I am curios if there is any noticeable effect of closing the trailing edge to turtle deck gap.
Larry, which gap were you referring to?

[n85ae]

My 80 old Dad with a PhD in Aero Engineering just looks at the Kitfox when I ask
him questions about aerodynamic improvements, shakes his head and says
things like - Don't waste your time, just go fly it. :)

Jeff

[n85ae]

I'll elaborate a bit more. When I have 8.50x6 tires on the plane instead of
6.00x6 tires. I can't tell the difference that they are on the plane except for
the ground handling changes ... I still get same airspeed, etc. So my conclusion
is the plane is so draggy to begin with, it's basically a lost cause. So just
go fly the plane is probably good advice. :) On the other hand it's a hobby
so why not?

Regards,
Jeff

[Slyfox]

sorry things got off track. If you are talking about the gap above the doors between the wing and fuse. I sealed my off mainly for comfort. same with the back section where the turdle deck is. If you are trying to make the fox faster, I agree, not going to happen. now for winter ops, nice to do. Now for the gap seals on the rear. The rudder, it's like putting on power steering. make sure that one is closed up. the elevator, not sure. I did mine. You can put the tape in there to see if it helps. If it does and you want something that looks better, than forgo the improvements. my take.

[SkySteve]

When I gap sealed by elevators I did see a noticable difference both in landing and take off controll. I fly a nose wheel plane and I can keep the nose wheel off the ground until I'm about stopped which really helps when flying into backcountry rough airstrips. Same with take off. I pull the stick all the way back for take off and the nose comes off the ground amost immediately, then I let the nose back down (off the ground) and just keep it off the ground during take off. I usually set the flaperons 1/2 way, then when I want to get off the ground short, I pull the flaperons all the way when I'm going about 30 mph indicated. The plane leaps off the ground. I lower the nose to get airspeed and slowly bleed the flaps back to zero.

I haven't gap sealed the rudder yet, but I've been meaning to. Sounds like I should try it.

[kitfox2009]

Hi Guys
If you look on the pics in my album you may get an idea of how I did my elevators. Used a cleverly cut length of foam pipe insulation and Gorilla tape!
Been over 2 years and 200 hours with no problems so far.,
Have fun
Don

[jrd]

Sorry if I am posting wrong but I have never done this before. I am building a KF 5 Vixen. I have modified it to taildragger or tricycle. I am in need of a motor mount for a Stratus Subaru conversion engine. I tried everywhere I could think of, even tried AIRDALE but trying to get hold of that guy is a waste of time. Can anyone help with this or will I have to build my own? I'm not a welder I can just stick metal together.
Thanks
Jim D.
jrdepd@verizon.net

[mr bill]

Lowell's version takes some effort to accomplish, but gives really superior results.

[airlina]

Saw the cub crafters gap seal at 200 bucks a copy. Being a thrifty Kitfoxer I went to the depot and found pipe insulation to fit the tubes, then sprayed it with a rubberized aerosol spray for waterproofing and attached with contact cement. Total cost of about 10 bucks for the same result. Bruce

[Dorsal]

And do you notice a difference?

[airlina]

Finn, About the only time I noticed any difference is in the flare. My elevator inputs yield more results than before the seals. The "feel" is more positive in the flare. I have the IO-240 up front so I need lots of elevator authority at slow speeds. The trim assist spring system and gap seals provide good control. Would I do the gap seals again,yes its an easy mod that is cheap. Bruce

[Dorsal]

Thanks Bruce

[t j]

Airlina, I like your idea. Can you say a little more about the rubberized aerosol spray for waterproofing?

[airlina]

I just found the can of stuff I used-got it either at lowes or the home depot and its called performix plastic dip multi purpose rubber coating. I wanted to make sure the pipe insulation foam would repel water so i used this to coat it before installation. They also make that dip rubber coating for tool grips that could be brushed on (Its pretty thick though) same company as the spray. Bruce

[t j]

Okay thanks for the info. I'm going to look for it.

[SkySteve]

Airlina,
Your gap seal looks very nice. I'm trying to understand how you installed it. Did you just basically cut the foam tubes in half (or less) and then just kind of "mush" the halves in place, back to back? And, what size foam tubes did you use? I'm guessing this was the foam insulating tubes used for water pipe, etc. ... And, did you glue them to the horizontal stabilizer and elevator?

[airlina]

Airlina,
Your gap seal looks very nice. I'm trying to understand how you installed it. Did you just basically cut the foam tubes in half (or less) and then just kind of "mush" the halves in place, back to back? And, what size foam tubes did you use? I'm guessing this was the foam insulating tubes used for water pipe, etc. ... And, did you glue them to the horizontal stabilizer and elevator?

Hi Steve, they say pics are worth a thousand words, so here is a brief tutorial on how I made my cheapo gap seals. Indeed the material is simply pipe insulation from the depot or lowes. On my Series 5 , my horizontal stab and elevator tube diameter where the seal is installed is about 1 and 1/4 ", so I used a 1" pipe insulation (I suspect 3/4" would work fine as well). Don't know if all models are this diameter. I needed roughly 8 feet of material to cover all gaps. You don't cut it in half , that would give the wrong shape to the foam. You have to replicate your empennage tubes with a simple cutting jig as shown in the following photos. I had a piece of 1" copper on hand but pvc would work in about a 1'' diameter. Once cut to size , I initially tried to wedge them in place , but test flights revealed that elevator travel and propwash would move them slightly, so I contact cemented them in place to each tube. As the elevator moves up and down the radiused part of the foam roll on each other. When cementing in place , put the seal in place when the cement is still wet so you can reposition them to final position before it dries. I would do the stab seal (forward one) let it dry then the elevator (aft one) so you don't disturb the installed one. Do not know if the gap distance is the same for all Kitfox models so you may have to find the right foam for your installation. Hope this helps Bruce

[SkySteve]

Bruce,
Absolutely wonderful explaination. And, you're right, pictures are worth billions and billions of words (or, something like that)! Thanks again for the explaination and photos. Even I can follow you now.

[Micro Mong Bldr]

Wing to fuselage gap was my original question.

Larry

[Slyfox]

when you say wing to fuse. are you talking about the area above the door or behind the door or all of it. I sealed off the area from the front windscreen to the back of the door. cuts out the cold in the winter time. I went and put fabric there, glued it in and then did the normal painting. well mine is still pink. haven't got around to finishing it. than there is a small wide area from the wing to the wood parts(about 1/8 inch or so) on the fuse that in the winter time I throw some tape on there. you can't seal that, when you move the wings that's the join section.

[Micro Mong Bldr]

Seals where the wings fold...
Larry