I have heard people using iron on film over silkspan on open bays.  That way you could get the best of both worlds.  A good strong substrate, and a puncture resistant, fuelproof surface.  I am thinking about building a sport (flight streak) plane this way to try it out.  Dyed silkspan, a few coats of clear dope, and 2mil lamination (combat) film over the top of it.  The slikspan won't need to be compleatly sealed, and the film won't sag attached to the paper.
 
Does anyone have any experience with this technique?  I know FF'ers have used it.

Dave

Dave,
What Busby said.
But, to answer your question -
I have done it. When a polyspan covered wing started getting "heavy" with clear, to seal the pores, and I still had color to apply, I "opted" for Ultracoat over the P'span.
Worked fine, and no bubbles as the polyspan was still a little porous and air was not trapped.
R....

Can someone confirm something for me? First, silkspan is not silk, but tissue, correct?
This topic is about film on silkspan? I always thought this system was tissue on film, to give weight and strength advantages, plus the looks of old fashioned tissue? I find it hard to believe there are many (or any) advantages this way round.

The silkspan would keep the monocote from sagging and no painting was needed.  Later monocote changed its product to a thinner and non sticky type mylar and thus ended the "need" for silkspan. But many continued to do it "because that's how we always do it".  Sound familiar??

Ty;

I could see an application for using silkspan under Monocoat on something like a Classic I-Beam wing.  I-Beamers need the ability of a covering like silkspan or silk to minimize flexing.  While Monocoat is more puncture resistant, it will also stretch a little under load, where silkspan or silk won't.  That characteristic will allow the wing to really flex, and flex is not good in I-Beamers.  Its a mistake I only made one time....   

However, were I to build another I-Beam wing ship and want to get it finished quickly, silkspan followed by Monocoat might be just the ticket.

V/r

Bob

Bob, Bob, Bob, my dear friend. Monocote on any I beamer is against the law. For shame even thinking such a thing.

But hey, if you want to waste all that time, money effort and get laughed off the field, why be my guest. I wont' laugh at you, but behind your back I might snicker. 

Sorry, I couldn't help myself. Three cups of coffee. 

Actually, it already happened.... (the admonition for Monocoat on an I-Beam).

I was in a tight.  The year was 1974.  One week before a contest and I had damaged my ship.  That was on a Sunday.  The wing construction was a modified I-Beam that I had come up with that built flat on a table (and then on some blocks when I flipped it over)  that used a composite rib in the center, but the traditional I-Beam strip rib after the center sections.  The wing installed into the fuse conventionally as well, e.g. a full size cutout in the fuselage.  I had all repairs less recovering the wing done by Wednesday, but not enough time to finish.  And, I needed to get in a few flights to recheck trim, etc.  No time for a dope and silkspan covering job.  So, I rolled out some Monocoat and had the wing covered in a few hours.  A little more time had my AMA number on the wing.  Next day I was at the flying field.  One the first flight I noticed the flexing.  Third flight, and said wing folded for good.  Some there remarked the effect rather spectacular.  

But I did have all the pieces in two very tidy bags as I went to the trash can.  My fellow club members thought that to be most considerate...

That being said, my favorite finish on I- Beam wings is dyed silk or silkspan with a clear dope finish.  I always thought the effect in the sun was beautiful.  When I lived up North, the finish held up pretty good for a couple of years (if the plane lasted that long).  Down South, the UV intensity fades it very quickly.  I figure if we can power I-Beam ships with something than our beloved OS/Fox/Veco 35s and ST 46s, we can probably cover them with Monocoat.  It is only a minor heresey.  I doubt it will get me burnt at the stake, and at the very worst you will just drink my beer.

V/r

Bob