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Building Tips and technical articles. => Building techniques => Topic started by: Bootlegger on March 06, 2011, 05:08:06 PM
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#^ Have any of you fellow's used 1/64" plywood for wing sheeting?
It should give a good finish, but what about weght? I plan to look at a 550 sq in wing for this set up, and plan to adhere it with slow epoxy.
Any suggestions will sure be 'ppreciated..
Thanks, Gil :!
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Hmmm, I've used 1/64" ply for profile fuse sheeting. Worked pretty well. Might be OK on a foam wing, I guess.
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And further to that question, how would it compare for cost to contest grade balsa?
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Gil, you're kidding right? Stick with balsa. Pick up a large sheet of 1/64th ply. Pick up a same size sheet of 1/16th balsa. Capice??
Ty, I weighed 1/64" ply one time and found it was awfully close to the same weight as "ordinary" 3/32" balsa. Now maybe that's my memory playing tricks, and I don't have a sheet of ply to try it now. Maybe somebody could actually put a sheet on the gram scale and let is know.
Regards,
Bill Lee
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Ty, I weighed 1/64" ply one time and found it was awfully close to the same weight as "ordinary" 3/32" balsa. Now maybe that's my memory playing tricks, and I don't have a sheet of ply to try it now. Maybe somebody could actually put a sheet on the gram scale and let is know.
Regards,
Bill Lee
Wouldn't the 1/64 ply absorb less glue for the sheeting and paint as well (along the same line of thinking of using thinner more dense 1/16 balsa in place of punk lite 3/32)? Wonder how big a difference in weight the overall process would be?
James
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hi Gil,
Back in the Dark Ages, I skinned a couple big R/C foam wings with 1/64th ply. The actual application process (attached it with "Southern Sorgum"), finish, and strength was great. Of course I have NO CLUE as to how much it weighed.
Big Bear
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A couple years ago I weighed a few large pieces of 1/64" plywood and found the density to be 55 - 60 lb/ft3 or about .0083 oz/in2 of area covered. Compared to a 1/16" thick sheet of 7 lb/ft3 balsa, the 1/64" plywood sheeting would weigh approximately 57.5/(7x4) or twice as much per square inch of sheeting.
If you want to see how much weight that is - without finish! - multiply your wing area by about 2.08 for surface area (top + bottom, curved). Then multiply by about .0083 oz/in2 to get the weight of the plywood skin. Take half of that for the balsa (for 7# balsa). Take proportionally less for whatever contest balsa weight you have. For example, your 550 in2 wing would have about 440 in2 of unflapped area (assuming 20% flaps). A 1/64" plywood skin would then weigh about 2.08 x 440 x .0083 = about 7.6 oz.
SK
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Thanks, Serge. I'm not real sure the trade off is worth it for me (on a stunt ship!). ;D The weight of the ply covering alone would be close to what I would hope the whole finished raw wing would way, that size! LL~ Doubt that I could make up the difference in the "finish".
On the old R/C jobs, it didn't really seem to matter. Plus I never flew any R/C competition. LL~
Bill
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Yea, I didn't want to comment on the probable weight.
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Yea, I didn't want to comment on the probable weight.
actually you don't want to commit to the very real high cost of that 1/64th ply. balsa prices are really bad but Plywood prices have gone insane especially that 64th stuff.
Oh and I also skinned R/C wings with ply and the advantage was the superior finish that you could put on a wing that had no flex to it. Also at the time the prevailing finish was epoxy paint. You all know that type of paint is not the best choice for flexable covering like paper or silk. 1/64th wasn't bad price wise in the 70's and you were able to buy it in sheets wide enough to cover the wing. You didn't have to butt glue balsa sheets together, no sanding balsa sheets, what wasn't to like about it. the pattern was wide open at 100 MPH and motors actually were encouraged to make lots of controlled power.. R/C really was fun back then.
Dennis
Dennis
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...... the 1/64" plywood sheeting would weigh approximately 57.5/(7x4) or twice as much per square inch of sheeting.....
With a 1/64th in. ply skin you could reduce the internal structure by quite a bit, it's stiffer and 6x stronger than 7 lb. balsa. Maybe 5 in. rib spacing, smaller spars, significantly less finish required. Plus 1/64 in. ply is very hard and would not be subject to hangar rash.
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Somewhere on this site, Clancy Arnold has some pics of a Ringmaster he covered with 1/64th ply to use as an indestructable trainer
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#^ Guy's I sure do want to say "Thanks for the responses" especially to Ty M, you "waskelly wabbit".
I am gonna pass on that idea, and stick with the balsa sheeting instead...
Again thanks, :P :P
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With a 1/64th in. ply skin you could reduce the internal structure by quite a bit, it's stiffer and 6x stronger than 7 lb. balsa. Maybe 5 in. rib spacing, smaller spars, significantly less finish required. Plus 1/64 in. ply is very hard and would not be subject to hangar rash.
Not sure I would agree with this, 64 ply actually has LESS rigidity than balsa, at least as far as deformation between supports. You still have to keep the skins from moving relative to each other, I don't beleive that spacing ribs 5 inches would be either productive aesthetically, or structurally. It would be easy to put a nice finish on the ply, but it still needs support, or when you sand it, it will deform..
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My first experience using 1/64 ply. This original design uses 1/64 ply for wing fillets and cowling. Cowling is one piece wrap-around with a balsa front. I'm sold on the stuff!
Floyd
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HI Floyd,
1/64th" ply has some wonderful attributes, but using it as a wing covering might be a tough one for C/L stunters. Just can't get past the weight issue.
Layers of thin ply, laminated, makes some nice landing gear that are good in usage and not too heavy. It can be easily molded into some nice configurations.
Big Bear
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I forgot to mention that the landing gear "spats" are made from one piece of 1/64 ply, wrapped around and epoxied at the rear. Quite an easy way to do that!
Floyd
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I just used some 1/64' plywood and was disappointed at how much weight it added. I weighed it (not realizing that Serge had already done so) and got .0091 oz./square inch. That's equivalent to .0098" of carbon fiber composite. I'll use carbon next time.
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I have sheeted many an R/C Pattern ship foam wing with 1/64th where weight wasn't so critical compared
to the strength it gave the wing. But the weight added to a control line wing is just too much compared
a balsa covered wing. We are doing built up profiles these days though and using 1/64th on the sides
of those is great with the end result a very stiff box and easy to finish.
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At the suggestion of Tom Farmer (many years ago) I started covering the sides of my profile fuse's with the 1/64" ply and was amazed at the extra strength that it added, also the stab doesn't twist up and down.
I now build my profile fuse's from 3/8" balse, and cut out the sides from back of the flaps to stab l/e and install geodetic 1/8" diaganel's (sp?).
Again thanks for all the suggestion's... #^
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mw~http://www.marinewaypoints.com/articles/JimBolland/2008February/BWSJan-Feb08part-two.pdf
This is ' the plywood Kings ' 1964 effort . He'd been in the Airforce , running the Yacht Squadron ,
and purloining the cable conduits out of the Mk 16 Spitfire now in the Auckland War Memorial; Musem
so that ' those Larikins ' couldnt fly the thing and wreck it , back in 48 ,As they were a bit careless
with their aeroplanes at times.
This was built with ' Aerolite ' glue , and is still going strong .
Theres many types of ply . I just got a piece of 1/32 , , 0.8 mm Birch Ply . ( Made in China )
Timbers regarded as having about the same strength / Weight as steel, but is bulkier.
The next Yak wing I do may well be ALL ply , bar spruce spars etc and fittings.
The old mans idea was it needs about 2 percent curveature to provide strength
" Otherwise it'll just flop around , it wont have any strength.Havnt you ever seen the bonnet of a car "
As in a flat sheet hasnt got a lot of resistance.He mustve been right, the big 73 Chrysler Hardtops
bonnet with just the perimiter frame left to lighten it , flattened off peceptably after a doseof high speed
touring.
A tapered wing is going to use its benefits most advatageously .
------------------------------------------------------------
William Towns , the Aston Martin -Lagonda Coach work designer produced large ' Mini Moke ' like
V-12 Jag powered 140 mph TIMBER chassis / bodied vehicals.
Marcos produced fibreglass , Timber Chassised cars.
Eventually they changed to steel chassis, as niether
boat builders or panel baters would touch accident repairs.
Marcos was Marsh and Costin , Costin , an Aerodynamisist
did LeMans Lister Jaguar and Maserati V-8 coachwork design.
And pedeseded Lotus in that concept aerodynamically.
Zagato who did the bodywork for the Maseratti to his design
didnt realise the importance of the placement of the inlets and
outlets.So at leMan's a large hole was chopped in it to avoid
the driver assphixiateing as well as roasting.Its the details that
count .
Designed to make use of the Ellement , such as the skinning for
the front of a Beringer Wing, or Namely the structure itself , it
" Has Promise ".
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#^ Have any of you fellow's used 1/64" plywood for wing sheeting?
It should give a good finish, but what about weght? I plan to look at a 550 sq in wing for this set up, and plan to adhere it with slow epoxy.
Any suggestions will sure be 'ppreciated..
Thanks, Gil :!
Ref. 1/64 over foam wings: For RC models, IMO, best way to go. For CL Stunt, well it may not be the best for weight.
My way to skin a foam wing is somewhat less than most but it does reduce weight and I have never seen a bubble after sitting in the sun all day. I have 1/64 ply wings in the barn over 15 years old and still good.
Not for a limited time use. This takes a while. :##
Get all the magazines, or such weight you can find. Using the creme colored wood working glue such as Titebond, etc. mix with water 50-50 to 60/40 glue / water and stir well. Brush both the skins and the foam. Place in the forms - sitting on a flat surface - and get all well straight. Add weights. Weights need to be evenly distributed.
Come back after several days. Remove the weights. The skins, especially balsa, will look all wet and rotten. Let them dry for a day or so and back into the forms for another week. If it is really wet, a couple sheets of thin paper towel between wood an form will help.
Mix up some finishing resin and thin it a tad with alcohol or epoxy thinner or whatever you use. Throw some micro balloons in and stir it again.
Brush it on and use the monokote gun to heat (Strong Warm) and thin more so, as the epoxy will run thin. Be careful to not get hot enough to cause a bubble. Let it set for at least a day. Ply can then be sanded to a very smooth surface.
Use of "white glue" will cover well between foam and wood. The water will thin it out to get complete glue coverage. Complete drying will then reduce weight considerably as compared to the other favorite methods of skinning a wing.
It doesn't take a lot of paint to get a decent finish thereafter.
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I just used some 1/64' plywood and was disappointed at how much weight it added. I weighed it (not realizing that Serge had already done so) and got .0091 oz./square inch. That's equivalent to .0098" of carbon fiber composite. I'll use carbon next time.
One wonders what fraction of the weight is the glue used to hold it together. It's disproportionately dense.
It's wonderful stuff to have in the field repair box, heavy or not.
Brett