Re-covering with Polyspan

[John Park]

Folks:
Rescuing a seventeen-year-old model from the darkest recesses of the garage roof, I've found that the heavyweight (21 grams per square metre) Modelspan tissue on the open areas of the wing had gone brittle and useless: re-covering those open areas with Polyspan (with which I have no experience) therefore seems like a good idea.  The stuff I'll be using is actually a Polyspan-type polyester tissue from Mike Woodhouse here in England, and he offers it in three weights: light (15 g/s.m.), standard (25 g/s.m.) and 'reinforced' which is so heavy I can't imagine using it.  The model is 500 sq. in., 50" span and weighs 36 oz. with an OS .25FP-S: the wing has a D-tube L/E and is nice and stiff even without covering.  I'm a weight-saving fanatic, so would it be all right to use the lightweight grade, or would 'standard' be better, bearing in mind that the weight penalty would be very small?  All advice gratefully received.

Regards
John

[Russ Main]

Hi John,

I recently used the poly span and the results are great. I am not sure what the weight is of the poly span I used but I believe it is much stronger than tissue or silk span. It does have a face and back side. If you put the back side up then when you put dope it on these little hairs pop up and it is a tough job getting them smoothed out. But I applied it dry and doped the edges, once dry I used my wife's hair dryer and it shrunk the poly span, not real fast but it did a great job. Then a couple coats of dope and its good to go. The edges are tough to get lay down too, so I use gloves when applying the clear dope so I can use my fingers to make the edges nice. My first attempt with poly span was the attached Brodak Mustang image. I have used it on 2 other kits this winter and have not had a problem. So I would think you can use the light weight and maybe the source has a recommendation too?

[John Park]

Russ:
Many thanks - this is the sort of advice I was hoping for.  I think I'll try the standard weight for a first attempt, and hope I can make as nice a job of it as you have!  (Birthday coming up, so a decent heat gun goes on the list.)

Regards
John

[john e. holliday]

I've used the Poly-span we have here in the states many times.   As said make sure you get the dull side down.   It is great to work with and with patience can be made to conform to wing tips.  Need a good iron and/or heat gun.

[Bill Little]

One word of caution.  Beware of a "real" heat gun.  It will burn a hole in the Poly Span quicker than you can see it.  Keep it moving at all times and don't hold it too close!  I love poly span, it is woven polyester and so much more resistant to punctures than tissue, silkspan or silk that it isn't funny!  Plus, you apply it dry because water will not shrink it.

BIG Bear
RNMM/AMM

[Allan Perret]

I had used Polyspan on a couple of models with good results.  Then Bob Hunt made me realize there was a "Polyspan Lite".  So next model I gave that a try and it was so lite that it still had pinholes with the same amount of dope that would have filled the regular Polyspan.  So I felt like in the end it did not save any weight and was not as strong as the regular. Don't have any clue what your heavier version is, but would recommend you go with the middle weight..

[Motorman]

How heavy is the stuff from Stunthanger Hobby?


MM

[John Park]

Folks:
I'm really grateful for all the feedback I'm getting - medium-weight it is, and go easy with the heat gun!  The model's called 'April Witch', by the way, so I now have to work up some good graphics for the re-covered wing, based on the cartoon witch-on-a-broomstick from the title sequence of 'Bewitched'!

Regards
John

[john e. holliday]

So far as I have seen there is only one weight of Poly-Span(Poly-t) from Stunt Hanger hobby.   Used to get it from Jim Snelson, but he has disappeared.

[Douglas Ames]

Folks:
I'm really grateful for all the feedback I'm getting - medium-weight it is, and go easy with the heat gun!  The model's called 'April Witch', by the way, so I now have to work up some good graphics for the re-covered wing, based on the cartoon witch-on-a-broomstick from the title sequence of 'Bewitched'!

Regards
John

Hi John,
I'm covering a Blackhawk (SIG) Fokker DVII right now using Minwax Polycrylic instead of dope (plus a glue stick to initially tack it down).
I CA'd the tip overlap too.

Also using a heat gun... put it on LOW and place your other hand just above the surface and sweep the gun and your hand, watching closely when it gets taught. IF IT'S BURNING YOUR HAND, THE GUN'S TOO CLOSE! 10"-12" is a good start.