RANS S6 ES Skin Change

Richard Fitzpatrick · Post by **Richard Fitzpatrick** » Thu Dec 01, 2011 9:52 am

In the next few months I intend to renew all the skins except the wings which were done last year. I have studied the build and spares book and looked at as many on-line pics as I can, so feel confident about the job. Except for the front part of the fuselage. How do I get at the lace strings at the firewall? Do I have to remove the firewall? A close look does show a small gap, about 8mm, behind the firewall material but am unsure, without dismantling now, how much access this will allow.
I would be grateful for any advice/pics on this.
Richard
Hants

Bill Scott · Post by **Bill Scott** » Thu Dec 01, 2011 9:47 pm

Hi Richard,
No need to remove firewall. Have you got the build manual? If not, I can copy the appropriate section and email it to you.
Fusealge is ok to do, the tail surfaces can be very fiddly and time consuming, but it's not (quite) rocket science

Richard Fitzpatrick · Post by **Richard Fitzpatrick** » Fri Dec 02, 2011 5:21 pm

Hi Bill,
Yes, I have the build and spares manuals but neither seem to show lacing up with the firewall in place. Now that you say it can be done, I will have a bit more confidence - even though I still cannot actually see how I can get to do the lacing up with the firewall in place. Thanks for the tips also. I finally managed to work out (with the build manual) how to re-skin the elevators and will make up the "special tool" to assist in this.
Thanks again
Richard

Bill Scott · Post by **Bill Scott** » Sat Dec 03, 2011 11:06 am

Ah yes, the elevators

I brought bthem home and thought that it would be a quick job !! The fuselage is probably the least problematical, just need to take your time with the tensioning. Work around the airframe side to side making sure you tension evenly. I found it seemed beneficial to to leave it a few days after getting near final tension, then return and do final tensioning. Heat gun is the exciting bit

Firewall: With cowling removed, it's a doddle. There are flaps at the leading edge of the covering, they go around the corner to the firewall face. The leading edge flaps are laced to a 'lace up tube' which is inboard of the firewall edge. Get the front half around the cockpit reasonably in place before working back up the fuselage lacing to the tail. Then you should get a respectable result.
Remember, you have options until you start using the heat gun. You can always loosen lacing and adjust tension, but that is not so easy when you've used the heat gun as you are then shaping the skin to some extent.

Richard Fitzpatrick · Post by **Richard Fitzpatrick** » Sun Dec 04, 2011 11:33 am

Hi Bill,
The penny has finally dropped after your last reply. One of the previous owners (probably the actual builder - who did a great job) has added an extra padding to the engine side of the firewall (soundproofing methinks). This has what looks like a metallic foil covering which I thought was the actual firewall. Once you mentiond the tubes for the lacing, all became clear.
I will follow your advice regarding taking the time to get the creases out, etc. Also understand that with the heat gun there is no real going back!
Thanks again for the advice - much appreciated.
Richard

Bill McCarthy · Post by **Bill McCarthy** » Sun Dec 04, 2011 2:31 pm

Bill and Richard - before you shoot away - I have reskinned my Sluka tail feathers with "lace on" covers. These have been tightened to the limit of my ability but after a time they have relaxed. Can all Dacron be taughtened that bit extra with heat.

Richard Fitzpatrick · Post by **Richard Fitzpatrick** » Sun Dec 04, 2011 7:32 pm

Hi Bill,
I have no actual experience of this but my understanding is that it can be shrunk using a hot air gun. Hopefull Bill Scott will see this and add his experience to your question. He did say though that it is best to leave a day or so after fully tightening as it will stretch and allow you to pull a bit more on the laces to tighten the fabric up that bit more.
Richard

Bill Scott · Post by **Bill Scott** » Mon Dec 05, 2011 2:56 pm

Hi Bill, Yes you can use a heat gun on dacron or, an iron. Dacron is the same stuff that is marketed as Poly-Fiber. Take a look at their website and you will find some interesting FAQs.

Bill McCarthy · Post by **Bill McCarthy** » Mon Dec 05, 2011 3:05 pm

That is a relief - thanks both !

Bill Scott · Post by **Bill Scott** » Mon Dec 05, 2011 5:39 pm

Richard Fitzpatrick wrote:Hi Bill,
I have no actual experience of this but my understanding is that it can be shrunk using a hot air gun. Hopefull Bill Scott will see this and add his experience to your question. He did say though that it is best to leave a day or so after fully tightening as it will stretch and allow you to pull a bit more on the laces to tighten the fabric up that bit more.
Richard

No! Not quite

You use the gun to finish the job, to get the skins fully taut, where it appears necessary, after you have fully tightened the lacing. Like I said before, there is no going back once you use the gun as you do shape the skin in place when working near the various edges. Good luck

JimCrawford · Post by **JimCrawford** » Mon Dec 05, 2011 8:19 pm

Note that both the Poly Fiber and Ceconite manuals explictly forbid the use of a heat gun and only authorise the use of a calibrated iron. Read the manuals to find out why.

Jim

Bill Scott · Post by **Bill Scott** » Mon Dec 05, 2011 10:56 pm

Interesting Jim, it is certainly common practice on aircraft with pre-sewn dacron skins. You do have to be careful, but the same applies to use of an iron.

JimCrawford · Post by **JimCrawford** » Thu Dec 08, 2011 4:21 pm

To paraphrase the Poly Fiber and Ceconite manuals, both for brevity and copyright.

Heat Guns; Why not? because there is no way to calibrate it. You run the risk of permanently loosening the fabric (by overheating - it will not recover).

Calibrated Irons;
225F is used to smooth the edges of finishing tapes and patches, heat form fabric around corners and remove fold creases.

250F is used for the initial tightening and to smooth wrinkles from seams before final tightening

350F final tightening

above 350F the fabric becomes permanently looser

Both manuals describe the procedures required to comply with their STCs, ie official approval for certified aircraft, so do not set out mandatory requirements for homebuilts. However it would be sensible to be at least aware of the manufacturers' best practice.

One issue that I have not yet managed to resolve is that of rib lacing. The manuals state " We strongly recommend rib lacing.....Fabric cements were never meant to be the sole means of attaching fabric to ribs ", In flight an aircraft is subject to peel loads from lift which is trying to peel the wing fabric off the top surface......Aircraft fabric cements were never designed to resist this peel force".

I'm currently trying to decide between Poly Fiber and Ceconite to recover a glider and I've never seen a rib laced glider. My Nipper, not covered by myself, is not laced but it may well become so.

It is not clear to me how this applies to laced on skins. If you heat shrink such a skin then, if you take it off, then you cannot heat shrink it again on refit. That would make it a once only removal, or should you tension the skin with the lacing only?

Jim

Bill Scott · Post by **Bill Scott** » Fri Dec 09, 2011 5:38 pm

With pre-sewn skins you should only need minimal use of the heat gun, purely for finishing. I agree that there is a risk, but the same would apply to an inaccurately calibrated iron. Good point about ribs, not an issue for the likes of me as the pre-sewn wing skins on the Rans S6 have pockets sewn in for the ribs. Short of having to repair the structure of the wing, it should be possible to avoid removing the skins during the course of their service lives. There are zips in the underside that afford good access where needed. Over the pond, it is common practice to lacquer the dacron skins on the Rans, Sky Ranger etc as a means of prolongig the life against UV degradation. In France it is common practice to paint dacron skins on similar types.