Captured wing

In another thread Ted F. mentioned the term "captured" wing and suggested that when this is the condition that only enough adhesive to keep the wing from sliding out of the fuse is needed.
This makes sense to me and with that in mind I was wondering how many have used silicone to secure the wing in profiles?

I have done this in two Ringmaster Jr's. The first was 12 years ago while in the Airforce and it worked well. It took several hits with no damage to the wing. I attribute that to the cushion the silicone was giving. I recently built another Ring Jr. for my youngest and secured the wing the same way. It hasn't been tested yet, but it will happen I'm sure some time this summer.

Wonder how large of a profile this will work on? Would it work on a built-up?

What do the Guru's say?

Good idea. I might try this.

Fly the Fokker yet?

Not yet Haven't had time to break that Enya in yet.
It will be a static display this weekend at a local fun fly.

Rick,

Bill Melton once told me that you can't build 'em to stand up to a crash, so you should build 'em to fly!

I think silicon is a poor adhesive for this purpose.

Build your ship normally, get a good tight fit on the fuselage to wing joint, and glue it properly with EPOXY.

I usually try to get a tight fitting joint, and I use thin CA to secure the wing. Then I make a proper wing fillet with Epoxolite (it IS epoxy). And it never gives any trouble, even when crashed it does not fail, and the nose does not vibrate, and the engine runs smoothly. To top it off, the wing fillet looks good.

I see nothing gained by some minimal or flexible joint between the wing and fuselage, and a lot to lose.

(Just my silly opinion.)

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"If you can't beat your computer at chess, try kickboxing."

Thanks for the response Larry. So you have tried this? Wasn't certain.
While I know you can't build to survive all crashes you can certainly build to minimize damage in some crashes.

The amount of flex I'm getting is minimal and while my test beds have been just on .15 size engines there appears to be no more vibration than an epoxied joint. Doesn't a well designed fuse and engine crutch eliminate engine vibration? Or is it the wing to fuse joint that is critical? Or is it a combination of both? Which one is more critical in elimination of vibration in your opinion? Is there any validity to a flexible joint helping to dampen vibration as opposed to a rigid joint enhancing vibration?

As far as fillets at the wing fuse joint, the two that I've done with silicone have far better fillets than anything I've ever done with epoxy.
I'm also still trying to achieve that professional type tight joint between wing and fuselage, but sadly I still have gaps, that to me look like caverns! The silicone is so much easier to work with in filling these gaps and making the fillets is a breeze. Isn't it also lighter than epoxy?

I appreciate your opinion, but do you have any actual experience in building and flying with a silicone joint?

BTW De Hill says pretty much the same thing as Bill. De points out that when you crash... something has to give.

I'm really more interested in whether this type of joint will last a resonable amount of time as long as the plane isn't crashed.

I refer back to Ted's statement that captured wings may not require a great amount of adhesive strength.

Rick,

Just curious...how do you get a finish to adhere to the silicone? No paint of any variety that I know of will stick to silicone, in fact silicone contamination of any sort is a huge problem when painting or trying to apply any sort of finish.

LAST EDITED ON Jun-26-03 AT 10:47 AM (CDT)
 
On the Jr. Ringmaster I just did I sprayed Black Rustoleum over it and it appears to have stuck quite well.

edit:
I might also add that finishes are of least concern to me because I tart mine up with stickers and monokote

Naw, Rick, I've never done a silicon joint on a model airplane. I used the silicon stuff on my dirt motorcycle for certain applications to seal and glue a joint. It's very tough.

As I said, use of a tight fight and epoxolite fillet on the wing joint works too well.

People worrying about stress risers should consider the value of a fillet, which distributes load smoothly over a larger area.

The difference in what you are talking about and what I do is that you are using a rubbery absorptive material while the joint I'm talking about is completely rigid.

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"Energizer Bunny arrested, charged with battery."

On full fuselage airplanes a bellcrank mount hard point is a light, strong addition to an epoxy joint. Have you considered a BBQB bellcrank mount?

LAST EDITED ON Jun-26-03 AT 11:43 AM (CDT)
 
> Have you
>considered a BBQB bellcrank mount?
>
>Al

Al,
I consider all of what you post here.
I'm still studying your post on the BBQB mount.

Most of my stuff is very, very simple, but usually turns out strong and reasonably lite.

Apparently no one has any real actual field experience with silicone joints. I quess I'll press on and report what I find out about the durability of these joints in smaller .15 size planes.

I will soon have two planes with this type of joint that we will be flying this summer.

Rick,

I'm with Larry on the use of silicone. I would avoid the use of flexible joints on any airplane you hope to last for awhile. How do you plan to get paint to stick on silicone? It is a great sealer, why do you think it is a good adhesive?

Personally, In addition to the hard spot of my BBQB mounts which carries most of the loads the rest of my wing/fuselage joins are a couple of layers of thin glass cloth and paint thin epoxy applied the entire length of the wing fuselage contact joint, inside and outside.

>Rick,
>
>I'm with Larry on the use of silicone. I would avoid the
>use of flexible joints on any airplane you hope to last for
>awhile. How do you plan to get paint to stick on silicone?
>It is a great sealer, why do you think it is a good
>adhesive?
>
>Personally, In addition to the hard spot of my BBQB mounts
>which carries most of the loads the rest of my wing/fuselage
>joins are a couple of layers of thin glass cloth and paint
>thin epoxy applied the entire length of the wing fuselage
>contact joint, inside and outside.
>
>Al

Al,
I'm NOT sure silicone is a good adhesive for wing to fuse joints. That's why I asked the question. I have, as I previously wrote, used this type of joint on a Ringmaster Jr years ago and it seemed to hold quite well after several encounters with the ground, from what I remember anyway. So I used it again on another Ring Jr my youngest son and I just finished. Photo's below.

I also have painted over the silicone with Rustoleum and it has not come off after 2 dozen flights. I'm really not concerned with finishes right now anyway. I have way to many other things I must master before I start trying for even a 15 point finish.

I respect your advice as well as Larry's, but I'm just asking if anyone has actually used silicone and not just assumed that it has no value what so ever as a wing to fuse adhesive and therefore has not even bothered to try.

I think I would heed your advice and use epoxy on a .60 size built up stunter, but I'm still not convinced that silicone will not work for the smaller sport/trainer type aircraft.

One advantage I see, is when you crash one of these smaller planes it should be easier to remove the wing from the fuse if it were attached with silicone vs. epoxy.
Also, for trainers and sport planes crashes are expected and a flexible joint appears to be better than a rigid one. Cox's PT-19 is the ultimate in flexible joint construction, would you not agree?

Thanks for your input Al, Larry, it is good advice, but is there not anyone out there who has actually tried this on something that was not going to the NATS?

Years ago, I flew a pair of profiles with a similar approach. The center section was double sheeted. Then a strip of inner tube rubber about an inch and a quarter wide was glued aroung the center section with Pliobond contact adhesive. Then sixteenth inch sheet with the grain spanwise was contact cemented to the rubber strip. Then the entire mess was glued into the fuselage (with Ambroid, I expect). Is that making sense? The idea was the same-it "gave" a little. The entire airplane except for the motor and bellcrank mounts was built with Pliobond. I can testify that airplane easily survived full power lawn dart tests.(Go to Barry Baxter's site and look up the Flexi-bull-it to see the original design. I had a stunt version with a thicker wing and longer fuselage, and a TD 051 powered little one with full flaps. Riley Wooten flew the entire pattern with the little one once. It's an interesting design and ahead of its time.

http://www.controllineplans.com/frameset2.htm

If you suspend the bellcrank from the FUSELAGE you can just plug the wing in using a ply saddle or something of the sort. This was the basis for Phil's plug-in-wing Slow Combat models from the mid-80s. There are still people flying planes like this - break a wing, just pop it out and tape another one in its place.

LAST EDITED ON Jun-27-03 AT 03:40 AM (CDT)
 
>Apparently no one has any real actual field experience with
>silicone joints. I quess I'll press on and report what I
>find out about the durability of these joints in smaller .15
>size planes.
>
(Edited in later - Well, dang! I managed to miss reading Isky's reply, so I ended up covering "old ground". Shucks!)

Not too many years ago, but prior to the arrival of arrow shafts as tail booms, combat foamie wings were sometimes attached to fuselages with tape instead of glue. We created a wing saddle of thin plywood (perhaps 1/64th, but I can't recall for certain), with a tight fit on the wing, and had a removable pushrod to control horn connection.

You could bring a couple of extra wings along, because fuselages were less likely to be total losses. Between rounds, you could untape the broken wing and slide it out. Slide in a new one and retape. Phil Cartier still sells a combat kit made more or less that way, I'm pretty sure.

I flew a sort of "leftover" one of those as a fun hacker with the same tape on it for 5-6 years. We took it out again relatively recently, with a different engine, and after a day in the hot sun, most of the tape came loose. In the prior period of usage, it was probably flown 20-25 times, maybe a little more, mostly in the late 1980's.

I would consider this to have been a "flexible" wing attachment . .

.
Kiwi

LAST EDITED ON Jun-27-03 AT 05:03 AM (CDT)
 
That "Li'L Hacker" he sells is a plug-in wing. Someone in the NE came up with a "Big Hacker" - same idea, just a lot bigger.

Check out Roy Glenn's models. Plug in, constant chord wing, hollowed out for lightness, bladder tank, balsa fuselage, 440 sq. in, weighs something ridiculous like 16 oz. complete with engine, for Speed Limit combat.

Phil's slow combat planes suggested using RTV to hold the wing on the ply saddle. My airplane i 2+ years old and dong fine. It doesn't look good, but it will hold.

The bel-crank is NOT in the wing, it is on a platform on the fuselage.

I'm with Larry, this is the same way I do it and I've never had a problem. Even bad in the days of cellulose/acetate cements it woked. There is no substitute for a good fit.

While I have never used silicon to glue in a wing, I have used it as a fillet on Monokoted airplanes. After solidly gluing in the wing or stab, I used a silicon seal color that matched the Monokote ( such as white ), or used black, which looks like a nice rubber seal. I think it looks pretty good, and is quite functional.

Silicon/RTV is actually a pretty good glue. If you have ever glued a tank in with the stuff then later cut it out and tried to clean off the residue you know what I am saying.

Wonder how it would work on the ARF Flight Streak..

After literally YEARS of securing Mo'Best fuel tanks with a couple of rubber bands, I used a couple of dabs of RTV to hold it into place. Shortly after that, I had TANK TROUBLES and tried to pop the tank out. It held so strongly that I ultimately got out the Jaws of Death (big channel-locks) and grabbed it and pulled it like a tooth..

It's darn good glue.

(But it is bad luck for me to remove my tank rubber band..)

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"If Barbie is so popular, why do you have to buy her friends?"

the original SC-2 Slow Combat from 1979 flying models is still up to date. You might want to beef up the motor mounts. The plug in wing, with a ply wing saddle in the fuselage works great. A snug fit is preferred, but RTV works fine 35-40 sport motors. The plug-in wing is good for up to about 1 hp. It is not sturdy enough for fast combat(2-3 hp).

RTV will soak up a lot of vibration. It is not a "strong" glue like epoxy so you need a large glue joint to withstand the horsepower. It is also very dense and can add a LOT of weight when applied generously.

The current SX460 plane from the Core House still uses a plug in wing on a pod and boom fuselage. Works fine for 25-35 motors if you want a sturdy stunt/combat trainer.

I got the idea for the plug in wing from the old 5cent gliders. I never could figure out how to hold a foam wing in a plane decently using rubber bands. It was heavy and things kept getting crushed.

Interestingly, the plane flys almost exactly the same even when the wing comes loose and the fuselage tilts out 25-30 degrees. The pilot can hardly tell the difference, but it looks really strange to the spectators when the plane is flying around with the fuselage pointing one way and the wing another. Makes me think alignment is highly over-rated.