Polyspan on an I-beamer

[Sean McEntee]

   Was doing some research on I-beam wings and there was mention to not use polyspan on an I-Beamer, though there was no explanation.

   True or false and why?  Thanks in advance.

[Gerald Arana]

I can't imagine why not..... You could put clear plastic (can't think of the name) over it and it would be real strong. 

Jerry

[Skip Chernoff]

I've not used Polyspan but have Monokoted two Ares wings with no apparent ill effects. Was flying one today!

[Jim Hoffman]

False.  Polyspan and I-beam is a fine combination.  My USA-1 is built that way w/ a dope finish.  Wing is stiff and robust.  I cannot think of a better combination

Jim Hoffman

[RC Storick]

False.  Polyspan and I-beam is a fine combination.  My USA-1 is built that way w/ a dope finish.  Wing is stiff and robust.  I cannot think of a better combination

Jim Hoffman

I agree, I have done a few I-beams with PolySpan and it works great.

[Sean McEntee]

Cool.  I did think that to be an odd claim.  Thanks all.

[Dan Berry]

Cool.  I did think that to be an odd claim.  Thanks all.

It's probably very easy to sand into the covering at the ribs on an I-beamer covered in polyspan. That might be the concerns with the warning.

[Dan McEntee]

It's probably very easy to sand into the covering at the ribs on an I-beamer covered in polyspan. That might be the concerns with the warning.

   I have yet to use Polyspan, but this is a concern for any type of covering over open bay wing structure. One help for that is to brush on an extra coat of dope or two over the rib, cap strip, sheeting, junctures so you have a little more material to work with. I got a box stock SIG Twister that needs covering and that will be my first experience with Polyspan. Nice square wing with no curved tips! I'll finish it off like Mike Gretz's original and be a flying memorial to a great guy.
   Type at you later,
   Dan McEntee

[john e. holliday]

Remember that Poly-span has a grain like silk span.   The grain goes span wise.  I have covered the Sheeks Staggerwing and Spitfire with Poly-Span.

[Jim Svitko]

Remember that Poly-span has a grain like silk span.   The grain goes span wise.  I have covered the Sheeks Staggerwing and Spitfire with Poly-Span.

I don't know if it is still available but at one time there was a product called Thermal Span.  Same as Polyspan but it is as strong in the chord-wise direction as span-wise.  No grain.

[Sean McEntee]

Dan I've use poly on a few models and that brushed-on dope does help...to an extent.

Thanks for your response folks.  I have a billet open for a classic model and looking at an Ares as a candidate--along with the Olympic and Shark 35 (cause the color scheme would be a no-brainer  )

[Randy Cuberly]

Hmmmmm...
I guess it works OK.

Here's a picture of my Collossus with....you guessed it ...POLYSPAN Covering!

Great stuff.  Just apply it with the right side (smooth) up and don't get carried away with sanding it until you get several coats of dope and primer on it.

Also make sure the rib surfaces are smooth before covering by "Long block" or "bar" sanding them, and several coats of dope lightly sanded before covering.  if the rib surface isn't very smooth you increase the risk of sanding through the covering be it polyspan or silkspan.

[Skip Chernoff]

Nice looking bird you've got there!

[Allan Perret]

I don't know if it is still available but at one time there was a product called Thermal Span.  Same as Polyspan but it is as strong in the chord-wise direction as span-wise.  No grain.

Still available from Harris Design, just got some couple of months ago..
Contact Shannon Harris                sharris@HarrisAerospace.com

[don boka]

The original I-Beams from Detroit in the fifties were Jap tissue done with Berry Brothers (probably no longer in existence) nitrate dope as a base and filler then butyrate dope for the color. Do NOT reverse the nitrate/butyrate process!
 I have done the same with Polyspan and it works fine. I built the model of Art Pawloski's Atom for the pictures in the construction article in MAN some years ago and did it with Polyspan, turned out fine.
Don Boka.

[Tim Wescott]

Dan I've use poly on a few models and that brushed-on dope does help...to an extent.

Thanks for your response folks.  I have a billet open for a classic model and looking at an Ares as a candidate--along with the Olympic and Shark 35 (cause the color scheme would be a no-brainer  )

If you like oddball, the Sheeks Knight is an I-beamer, and looks like it'd fly pretty good with a control system made with CF push-tubes instead of the original floppy music wire (it's a T-tail).  Just sayin'...

[Dan McEntee]

Dan I've use poly on a few models and that brushed-on dope does help...to an extent.

Thanks for your response folks.  I have a billet open for a classic model and looking at an Ares as a candidate--along with the Olympic and Shark 35 (cause the color scheme would be a no-brainer  )

   Well, if you decide to do the Ares, I have a signed and numbered print of the plan that Warren Tiarht drew up from Billy's original airplane ( copy #13). I think I have Ambroid plans also, plus some one else's.
  Type at you later,
   Dad