Author Topic: Composite construction for old speed designs? (Read 1079 times)

Andrew Tinsley · « **on:** September 18, 2012, 04:53:34 AM »

Hello All
I have been out of speed for almost 50 years and now I want to dip the toes in the water! I built an Arkansas traveller for McCoy 60 spark power. When I had finished carving the balsa fuselage, I had just about had enough of carving for the rest of my life! It struck me that it would have been quicker to carve a solid fuselage and used that to make a couple of female moulds, one could then layup the fiuselage halves (top and bottom). It may well take just as long to do this as to make a conventional fuselage, but at least making further duplicates (read crash damage!) would be simple and quick!
I have a composite fuselage stunter (not made by me) and it is a lot heavier than the balsa equivalent. Is this the reason for not going this route? However, using carbon fiber, I would think that you could build down to a weight, by not using so much epoxy or polyester and relying on the carbon fiber for strength?
I may well be talking out of the back of my head and ignorance is bliss! What do the experienced say?

Regards,

Andrew.

don Burke · « **Reply #1 on:** September 18, 2012, 01:03:10 PM »

Wisniewski and Nightingale were using fiberglass molded fuselages in the '60s. Their models were half pan type. They used first carved a solid mold as you're thinking but they were made two piece with a layer of kraft paper on the vertical center line to provide a reference plane and allow separation of the two halves after carving. Their carvings included wing fillets and the bottom back half behind the pan. The halves were then attached to a larger plate and used to make plaster female molds for the fuselages. Long process but they could easily make multiple fuselages afterwards. The moldings were just a couple of layers of thin fiberglass, sanded flat while still in the mold to provide a good joint. They used full span spars bolted to the pans and folded aluminum wings.
If using a full length pan the pattern can be one piece and just carved like a normal fuselage. IMO Makes it harder to incorporate things like fillets.

Andrew Tinsley · « **Reply #2 on:** September 18, 2012, 02:52:02 PM »

Thanks Don,
At least my idea wasn't too stupid. I never did give much thought to fillets though!

Regards,

Andrew.

don Burke · « **Reply #3 on:** September 18, 2012, 08:50:15 PM »

If the wing butts against the side of the fuselage there's really no need for fillets. An aerodynamics type told me along time ago that LE and TE fillets have a drag reducing effect because they effectively decrease the percentage thickness of the wing. He also said that fillets top and bottom cause a increase in drag over a right angle joint between the fuselage side and the wing.

My problem is always patience, making the master and the molds is very time consuming. And usually by the time I'm finished building something I always think, "I could have done that better if.....". So I tend to hardly ever build two of anything.

wmiii · « **Reply #4 on:** September 25, 2012, 10:20:58 PM »

Hi Don, I flew with Jim from 1958-1964. He made plaster molds, complete with wing fillets, full length pans. I must have built 8 of them, .29's and 60's. The tops were fibreglass. I have a bunch of pictures around some place.

Walter

Andrew Tinsley · « **Reply #5 on:** September 26, 2012, 10:06:27 AM »

Hello Walter,
I take it that the pans were of the traditional cast variety? If so, maybe I could do the same, before my aluminium casting abilities desert me from lack of use?

Regards,

Andrew.

wmiii · « **Reply #6 on:** September 26, 2012, 07:01:08 PM »

You are correct. I never was interested in the casting process. Just so I had a pan and a top, with aluminum wings when I needed them.

Walter

don Burke · « **Reply #7 on:** September 26, 2012, 07:15:48 PM »

Quote from: wmiii on September 25, 2012, 10:20:58 PM

Hi Don, I flew with Jim from 1958-1964. He made plaster molds, complete with wing fillets, full length pans. I must have built 8 of them, .29's and 60's. The tops were fibreglass. I have a bunch of pictures around some place.

Walter

I've still got a Nightingale FAI, K&B powered. Jim sold me one of his "A" kits. Included the wings, stab, spar fiberglass top and balsa bottom rear. that has one of Jim's tops. I originally had fully enclosed engine. Thinking at the time was expose the head and eliminate the cooling ducts, my best flight was in the low 140s when Bill and Jim were in the 150-160 range.

wmiii · « **Reply #8 on:** September 26, 2012, 09:11:39 PM »

I was in the Army at that time, don't know much about the halfpan airplanes. Jim had moved to California by then. I didn't see him or Bill again, till about 1969, I think the Nats were in California that year.

Author Topic: Composite construction for old speed designs? (Read 1079 times)

Andrew Tinsley

Composite construction for old speed designs?

don Burke

Re: Composite construction for old speed designs?

Andrew Tinsley

Re: Composite construction for old speed designs?

don Burke

Re: Composite construction for old speed designs?

wmiii

Re: Composite construction for old speed designs?

Andrew Tinsley

Re: Composite construction for old speed designs?

wmiii

Re: Composite construction for old speed designs?

don Burke

Re: Composite construction for old speed designs?

wmiii

Re: Composite construction for old speed designs?