03-11-2010, 11:59 PM
Well Mick, when it comes to covering I've only tried "Solarfilm" (since the mid 1970's when we used tissue paper on nitrocellulose dope). I've used Solarfilm on both framed structures and solid surfaces and it requires a different technique with each. The instructions on its use are usually included with the film, but the only thing that I've found tricky is getting the temperature of the iron correct - I was using a temperature which was too low to start with (being cautious) and that didn't help at all. A couple of things I did discover ...
1. With a frame structure like the upperside of your wing, tack along the outsides first. Don't be afraid to pull up sections you've already tacked down if there are wrinkles, you can re-tack these down again with the toe of the iron. This tip isn't mentioned in the instructions I've seen that come with the material.
2. With sheeted sections like the underside of your wing, you must start from the centre with the iron and work outwards to avoid wrinkles.
3. If you get some wrinkles that are difficult to remove by lifting the film and re-setting it, then don't worry too much because you'd be surprised at how even tight wrinkles can be removed by gently rubbing them with the toe of an iron.
4. As for warps (more likely in the wing of course) it's possible to get rid of these to a large extent by getting an assistant to twist the wing against the warp while you move the iron over both surfaces - this can happen hours or days after covering the wing. It's one of the things that makes the heat-sensitive films much better than the old tissue and dope techniques.
But, that's the extent of my knowledge - there are dozens of different types of films available and I've only tried Solarfilm. I've also only used an old clothes-iron with some flannel from an old westie-style shirt stretched over the iron and held in place by hand. I've had good results on using it on wings and on sheeted tail surfaces, but I've also tried putting it directly over foam as a "skin" and that was a disaster - I'll tell you about it some time at the field!
Good luck mate and remember that if it all starts going wrong, that you can rip it off by hand and still have your balsa handiwork ready to go again in another attempt!
SteveM
1. With a frame structure like the upperside of your wing, tack along the outsides first. Don't be afraid to pull up sections you've already tacked down if there are wrinkles, you can re-tack these down again with the toe of the iron. This tip isn't mentioned in the instructions I've seen that come with the material.
2. With sheeted sections like the underside of your wing, you must start from the centre with the iron and work outwards to avoid wrinkles.
3. If you get some wrinkles that are difficult to remove by lifting the film and re-setting it, then don't worry too much because you'd be surprised at how even tight wrinkles can be removed by gently rubbing them with the toe of an iron.
4. As for warps (more likely in the wing of course) it's possible to get rid of these to a large extent by getting an assistant to twist the wing against the warp while you move the iron over both surfaces - this can happen hours or days after covering the wing. It's one of the things that makes the heat-sensitive films much better than the old tissue and dope techniques.
But, that's the extent of my knowledge - there are dozens of different types of films available and I've only tried Solarfilm. I've also only used an old clothes-iron with some flannel from an old westie-style shirt stretched over the iron and held in place by hand. I've had good results on using it on wings and on sheeted tail surfaces, but I've also tried putting it directly over foam as a "skin" and that was a disaster - I'll tell you about it some time at the field!
Good luck mate and remember that if it all starts going wrong, that you can rip it off by hand and still have your balsa handiwork ready to go again in another attempt!
SteveM
Steve Murray