Help please - wing coring?
 

Does anyone have a link/photos for coring a foam wing? I'm considering doing this on a competition bird and was hoping someone could help me find my way.

Thanks!
Ken

RE: Help please - wing coring?
 

Hey Ken,

Here's some coring pics from the black magic thread.

http://www.rcuniverse.com/forum/m_36..._2/key_/tm.htm

Start post 28.

You getting into pattern or a new imac bird?

Bob

RE: Help please - wing coring?
 

I have heard of a method that cuts a core from root to tip...one core in front of the tube, one behind. It requires burning the wires into the core, then sheeting, then using these wires and templates to burn each core out of the panel. I have not yet tried this method, but I have seen the results and it looks good. This method also prevents the sheeting from having to span open (unsupported) bays in the foam core.

-mark

RE: Help please - wing coring?
 

Bob,

Thanks - that is exactly what I was hoping to find. This will be for an IMAC bird being built this winter.

Thanks!
Ken

RE: Help please - wing coring?
 

Hi Ken, Hi All,
This is what the Control-Line Stunt guys have been doing for eons. Typically they core out three sections, but if you are doing a plug-in wing you'll want to core oput two sections, leavinga wide foam spar that is maybe 3" wide at the root and 1/2" wide at the tip. First you bore pilot holes with a hot wire. This is kinda tricky. Then you sheet tha foam, using whatever weight or vaccum bag pressure necessary. Then after sheeting and sanding, the cutting bow wire is fed through the pilot hole, and templates are attached to root and tip. I have even cored just the section of the leading edge outboard of the retract mount by pre-cutting my template hole into the outer retract mounting false rib.

You might try going to the Stunt forums and asking for details. Try www.stunthangar.com and www.clstunt.com and look in the building technique sub-forum.
best of luck, Dean Pappas

RE: Help please - wing coring?
 

I wrote an article describing a successful technique I've used on 4 wingsets. It's in the next KFactor magazine.

RE: Help please - wing coring?
 

FlexibleFlyer - is there any way I can get a copy of your article after it publishes? I'm not a member of the NSRCA, so I don't get the K-Factor. I would be willing to join if I could get your article. Is there any way I could get a copy of just your article, though?

Thanks,
Ken

RE: Help please - wing coring?
 

Hmmmm....I think you need to join anyway, there's a LOT of good stuff in the K Factor, and we're trying to get more. More members=more stuff.

BTW it's a really interesting article. I do it differently, but it's an interesting enough technique that I may try it just to see how I like it.

-Mike

Editor, K Factor

RE: Help please - wing coring?
 

Thanks, Mike. I was planning on doing just what you did in your build thread, but if there is something better/different, I'd sure like to see that. Appreciate all the help.

Ken

RE: Help please - wing coring?
 

I'm not sure if it's "better", but it's definitely a viable alternative that will allow you to do some things differently.

Keep in mind that there is practically NO structural value to foam at all. Foam is there for one reason: to hold the sheeting in place, that's all. Open bays like I do works fine structurally, and removes mass from the tips. this has a 2 fold advantage: it makes the wing lighter, and it moves the center of mass (or panel CG) inboard. The effect this has is most noticable in snaps and spins. Snaps break on a dime and stop FAST. So, it's much easier to score well and control your snaps and spins.

You can still vacuum the wing using this method, but you have to vacuum the whole shuck, not just the panel. It still works very well and produces a really light wing.

With all that being said, I'm trying about 6 or 7 different techniques right now on my new planes. I like spars in my wings which adds an ounce or so, but these wings do NOT break.

At any rate, good luck.
-Mike

RE: Help please - wing coring?
 

I have cored out the in-board area of my wings ahead, inbetween and behind the spar areas and still retained the strength.
Mike is right about keeping the mass more towards the center of inertia. It helps in all aspects of rotation.

I save about 1.5 to 2 oz overall with this method. Thats only about 5% weight savings on a finished wing but it all adds up.

Mike Harrison told me to think of saving weight in percentages and you will see the overall picture on weight savings a little better.
Buy a tail wheel that is 20% lighter then then the one you use now. If you think in those terms you will come out a lot lighter in th eend then you think. 20% here, 10% there and before you know it you just saved 5oz in the whole build.

Lance @ AeroSLave has used the buried wire method in core his wings with good success. You may want to ask him about the proccess that he uses. email him at www.aeroslave.com


Smooth FLying...

Wayne Galligan