Covering an under-cambered wing with Oralight

[Jonathan M]

Any tips on covering the bottom of an under-cambered wing?

 

Just iron on the film as usual, or pre-coat the ribs with something sticky?

 

It's a 2mRES.

 

Edited March 26, 2023 by Jonathan M

[J D 8]

  I would use "Cover Grip" by Deluxe materials. Will prevent lifting when tensioning. Follow product instructions.

[Engine Doctor]

+ 1 for above .

[Jonathan M]

Thanks chaps 👍🏻

[Don Fry]

I attach the film to the lowest point of the under camber, along the entire span. There is always a spar here. Now once attached, it’s vital you don’t apply heat to that area, or it pulls away. So I pin a balsa strip to it. Then I attach the front and back, usual technique.

[John Wagg]

As Don -

I start tacking down on the low point of the under camber.

Assuming a flat longitudinal surface, I do the inner and outer ribs first and then tack the middle of the other ribs in between. 

Trying to keep the covering reasonably taut, I then do each rib ironing from the middle to the front, or back, making sure that each rib is stuck properly.

I have never used any "glue" preparation but it won't do any harm if you want too.

 

 

[Jonathan M]

Thanks Don and John for the tips on technique.

 

Its a carbon tube spar, so I'll need to adapt the principle to what's available... which will be to tack to the low points of the ribs themselves!

 

 

[J D 8]

 That is not as severe under camber like on early aircraft wing sections [ Bleriot XI wing in pic during cleaning] Cover Grip on each rib will ensure adhesion. As John W says above make sure each rib is stuck properly. Cheers, John.

[Greyhead46]

On my Se5a I used stitching as per the full size practice, I've had under camber covering lift in the past and didn't want to take the risk!