RE: Cobra Build Thread
 

Hi, I've been quietly watching in the background here. I've got a copy of these plans and have quietly lusted after the Cobra since reading the original article as a kid way back when. Someday I'll get into it, too many other projects at the moment.

I've thought about the wing construction for a long time - it is a major challenge in this build. My idea (untested, fwiw) would be to take advantage of the fact that it is constant chord. Cut some longer than necessary foam sheet, then cut out holes for the spars, servo pockest and wires (only to the length required) before cutting and sheeting a long, flat core. Once it is sheeted, use a table saw and cut the wing to get that angle of the joints between the panels right, and at the same time exposing the hole you made for the spar before sheeting the core. . At that point you should be able to slip your spar into the end panels just like an ARF. Build some small platforms to support the various panels as the glue dries. The angled panels would need the balsa sheet on one side cut back to fit ovr the spar, then re-glue the strip back on once the panel is setteld on the spar. A thin layer of fiberglass would 'unify' the whole structure.

Like I said, I haven't tried this, but I figured it was worth throwing the idea in.

Joel

RE: Cobra Build Thread
 

Joel,

Are you really some kinda long-distance mind reader? Your method describles the one I have used on two previous Cobras; and will use it again on this one. I'm a firm believer in foam wings and this one takes a little angle figuring, but it comes out just fine and looks terrific when finished!

This may not be good news to you, but we MUST be kindred spirits some way or another! Don't let that upset you too much......

Steve

RE: Cobra Build Thread
 

I don't have anyway of cutting the foam wings and don't even know what kind of foam I should use. Any help I will take with gratitude.

RE: Cobra Build Thread
 

Looking good.

RE: Cobra Build Thread
 

goirish,

In post #10 I listed three foam cutters who do a terrific job....
If you have somebody in your local club, use 1# insulation foam you can buy at Home Depot or Lowe's.....

Good luck....there are foam cutters all over the place.

Steve

RE: Cobra Build Thread
 

I have contacted the first two but no reply yet.

How hard is it to make a foam cutter that would handle this job. I have all kinds of wood working tools as I make some cabinets.

RE: Cobra Build Thread
 

I found these old post on it.

http://www.rcuniverse.com/forum/m_57.../tm.htm#577577

http://www.rcuniverse.com/forum/m_21...tm.htm#7667653

RE: Cobra Build Thread
 

Here is a very nice web page on it!

http://www.all3com.com/Hobbies/

RE: Cobra Build Thread
 

Here is a pic of the full-scale Cobra.

You know, I've seen bigger RC planes than this. Looks like it wouldn't be hard to make a 1:1 scale RC model of this plane.

http://www.all3com.com/Hobbies/sundancer.htm

RE: Cobra Build Thread
 

What kind of foam would you all suggest for the wings. White, pink or blue. I can get any of them at the local lumber co.

RE: Cobra Build Thread
 

Getting ready to cut the wings. Have the fuselage built up. Will post some pictures.

RE: Cobra Build Thread
 

pictures? or an update?

RE: Cobra Build Thread
 

Did this "Cobra Build Thread" just die on the vine because nobody is actually building one? Or is the builder/builders just keeping it very quiet with no progress reports or pictures?

Personally, I must admit I got sidetracked again and haven't done very much on this plane, but I'm somewhat surprised that all the initial interest has waned on everybody's part. Too bad....it's a cool plane.

If you're moving right along with this project, post some reports and pix to inspire the rest of us lazy slugs to get on the ball, eh?

RE: Cobra Build Thread
 

I have the fuselage framed up, the stab and rudder. I have been cutting foam to get ready to cut the wings. How are you cutting the slots for the wing braces?

RE: Cobra Build Thread
 

Slots for wing braces were cut on a radial arm saw; and the angles for joining the wings resulting in the gullwing were also cut on the radial arm saw. This was all done after sheeting the cores and returning them to their shucks for proper alignment. Not really sure if this method is any easier or quicker than a built-up wing, it just works for me; and the finished wing looks great. Good luck with yours!

RE: Cobra Build Thread
 

I will tell you that trying to build the wings the conventional way is the pits. I will try the foam way. If you cut it on the radial arm saw then you had to cut the length longer than the brace because of the radius of the saw blade. Is that correct? What kind of foam did you use? I made a club member a set for his senior telemaster out of pink and they turned out great. Thanks for the help.

RE: Cobra Build Thread
 

Finish cutting the wing brace slot to the proper length with a fine tooth Zona saw. Used white foam for the wings.

RE: Cobra Build Thread
 

Thank you sir: Getting better at cutting the foam. Will be cutting the wings shortly.

RE: Cobra Build Thread
 

Got my Cobra plans in this week. So nice of Air Age to fold them into a nice little 8" package. Really, why don't they even offer to roll the plans for an extra fee like RCM does?

RE: Cobra Build Thread
 

LOL,

Just noticed that this thread is in the "Beginners" forum.

A racing giant scale double gullwing bipe is hardly a beginners plane.

Thin we can move this to the Giant Scale forum?

RE: Cobra Build Thread
 

NO, but I will look around. A lot of the cutters I knew about are no longer in operation. I thought you started cutting foam a few months back. I was going to start using you!!:D

RE: Cobra Build Thread
 

I have been cutting foam and not to bad. I did take time out for awhile. My wife had a total shoulder replaced and we have been dealing with that. It was a lot worse than they expected so the incision was about 2 1/2 times longer than the normal one. In the spare time I have been building a Bud Nosen 1/4 scale Citabria to use as a tug for my sail plane. Going to put a 50 gasser in it.

I know you are going to the Toledo show, Right!!!.

RE: Cobra Build Thread
 

Irish, try www.eurekaaircraft.com i think they have a cobra bipe short kit, and the cut wings for alot of models
if your plans are form MAN, then you may be able to just buy their wing kit

RE: Cobra Build Thread
 

AmishWarlord,

Agreed....this plane build probably should be in the giant scale forum. It's for "goirish" to determine, however, as he started it; and perhaps he in the only person allowed to make the decision.

RE: Cobra Build Thread
 

Hey guys, no problem with me. I didn't know where to put it. But, I also don't know how to switch it to the other forum. Been building my Bud Nosen 1/4 scale Citabria and almost have it completed. Putting a 50 gasser in it so I will see how it runs and then get one for the cobra.