1/2A Cobra Foam Wings

Perhaps some of the 1/2A experts can tell me what type of foam is best suitable for making foam wing cores for the 1/2A Cobra? Given the small wing area and that the panels will be cored out, does the choice of white vs pink or blue foam really matter weight wise?

Hi Eggy,
I downloaded some 1/2A Cobra plans off the net. Can't remember the site. Looks like it would be real neat with a Norvel.
Are you going to cut the cores?
Bill <><

>Hi Eggy,
>I downloaded some 1/2A Cobra plans off the net. Can't
>remember the site. Looks like it would be real neat with a
>Norvel.
>Are you going to cut the cores?
>Bill <><

Hi Bill & other Cobra fans,
The plan is available here: http://my.pclink.com/~dfritzke/
It's a really nicely done plan.

There are several members in our club interested in building a baby Cobra. We will ask one of the guys in the local R/C clubs to cut the cores for us.

Hi Eggy,
I downloaded those. It is a real nice looking 1/2A stunt ship.
I would be interested if someone cut those cores.
Bill <><

>The plan is available here: http://my.pclink.com/~dfritzke/

I rang out this site. The plan downloaded perfectly. NICE.

I built foam planes for decades. Also, several I-beams when they were in style.

I think I could build one of these beauties as an I-beam quicker than I could tool up for foam. Depends on how many you want.

LAST EDITED ON Nov-14-04 AT 01:05 PM (CST)
 
Dow Styrofoam (blue), the only actual Styrofoam,
OwensCorning,"pink panther",
Shell (green)

In my experience, all of the above are twice as heavy and twice strong as plain "vanilla" generic polystryrene foam. The only way I would use them is if I could cut the cores to half the thickness.

I built a slow and an FAI with genuine Dow, years ago. It cost me about 2 to 3 ounces.

Better to stop and smell the balsa than burning foam.

LAST EDITED ON Nov-14-04 AT 07:35 PM (CST)
 
This little ship is a perfect candidate for regular white sytro cores, hollowed out and covered with SLC covering to save weight.
the only other way to do it and get a reasonably low weight would be conventional built up construction.

It's really a shame to see Wooley's Cobra done with a sheeted wing though. It was designed for I-beam. At least do a capstripped foam wing to simulate the ribbing!!!! A solid foam wing, with capstrips, would probably weigh about what the I beam wing weighed.

That stab looks suspiciously oversize for the Cobra too. But it's been a long time since I looked at the plans.

LAST EDITED ON Nov-14-04 AT 09:43 PM (CST)
 
how big should a 1/2a stunter be ...square inches....jim

>how big should a 1/2a stunter be ...square inches....jim

Hi Jim, It depends upon which engine you choose for your
model. I'm assuming you mean .049 cu" displacment: Cox Tee Dee,try
200-230 sq"'s,same for norvel, Paw diesel: 220-240sq"'s, Fora, Va
and Shurikens(I don't recommend these for stunt):250-300sq"...!
Cox Medallion: 190-220sq"'s Cox reed valve: 160-190sq"'s.
I still wonder if you are the James Ivey who flew control line in the So Cal area in the fifties...Hawthorne High...El Camino col..
etc..? Howdy, if you are him.

Tony G