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Building Tips and technical articles. => 1/2 A building. => Topic started by: Wayne Collier on February 10, 2007, 08:20:12 PM
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a little more sanding, a little more glue, a little more finish work then maybe...
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yeah---------it'll fly. It looks right.
Is that wing balsa? The grain looks more like Poplar.
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Shhhhhh I ran across a really light strait piece of popular and thought I'd give it a try. Light for poplar--still heavier than balsa but I'm only using enough clear paint for sealing and fuel proofing.
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I think you should still put ply doublers ( 1/32?) on the nose. The poplar will compress too easily when you torque the motor bolts.
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Yep, it'll fly. Looks good, and there is always the option of more power.
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I got a little more done. The wings and gear are actually attached instead of just stuck together for a picture. I said it was going to be clear finish but I had some tinted polyurethane on hand and wanted to give it a try. I'll use that clear dope for something else. While short of being a concrete block, this thing seems way heavy. I'm afraid to weigh it.
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Put a Norvel .061 on it--it pulls my 15-oz. brick pretty well. You can't be that heavy.
--Ray
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Got a good .09? I still think it'll fly, probably pretty well.
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Say, why don't you turn that plane around and give us a shot from the outboard side? I'd like to see how the landing gear is mounted.
--Ray
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I think that this particular piece of wood is strong enough to support this type of gear installation. The gear is one piece of tough 1/16th" music wire. I started with a piece that was a little longer than the estimated finished length. I bent it double with the help of a vice. About an inch from the bend, I spread the wire to the desired angle. I then bent the ends to accommodate the wheels. After installing wheels and collars, I ground off the excess wire. This produced a formed landing gear. I drilled a whole up from the bottom of the fuselage a little over an each deep and at an angle that slanted the wheels a little forward of the attachment point. I then epoxied the gear into the drilled hole. In the picture you can see a recess in the side of the fuselage. This is intended to keep the fuel tank from sliding around. In many ways this project is an experiment and I already see many avenues of improvement. I earlier commented on the weight. Actually I think it is still lighter than a cox plastic skyraider that I once owned. I've got the controls pretty much in order but not yet installed. Still mulling over line rake, if any, and amount of tip weight.
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Interesting. Tip weight should be enough to slightly more than counterbalance the weight of controls, leadouts, etc.--when you pick the plane up by the nose and tail, the outboard wing should droop slightly.
Line rake is related to CG--leadout guides at wingtip should be maybe 1/2" behind CG, up to perhaps as much as 1". Put your bellcrank wherever it's most convenient; it won't affect it. Maybe think of a washer under the front lugs of the engine to give a slight outboard offset.
I am curious about the weight of the model; also wing area? Span x averge chord.
--Ray
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OK, I bit the bullet and set the plane on my wifes kitchen scales (accuracy unknown). It reads about nine ounces as pictured in previous post. Wing chord at root is 5.5". At tip its about 2.75". If i did the math right thats an average chord of about four inches. Wingspan is 23 inches which would mean a wing area of about 95 square inches including wing tips.
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Yup, your math is good...9oz. is do-able, probably more like 11 or 11 1/2 with engine/tank. 95 squares makes a pretty high wing loading but you're not looking for high-level stunt capabilities anyhow. It should fly fine. Probably a little fast if you get a good .049 cooking on it. In fact, now that I'm looking at it in that light, it even looks a little like a team racer. Give us a flight report when you get to it!
--Ray
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Almost ready to test fly. Still needs tip weight. May actually try the first flights with the wood prop (6-3 zinger). Have better props for later (master airscrew and APC).
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I like it, it has really appealing lines, hope she flies up to your expectations. the tinted clear is a nice touch
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TeeDee .049--that oughtta pull it for sure. What length lines do you plan to use?
Oh, and put it on the scale again RTF, would you? Let's see where it ended up.
A very pleasing airplane visually. Still looks like a Team Racer, or Mouse Racer, or something--it looks fast.
--Ray
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Officially finished. Fired it up this afternoon but didn't try to fly it. I am still unsure of exact weight. The cheap kitchen scale I was using was already suspect, but since my 14 year old tried to weigh a three liter soda on it a few days ago it has really been wack. I think I can safely say its under a pound and optimistically say its around twelve ounces. Possibly less. I was really encouraged at the pull the engine had while running. (with a 6-3 wood prop) I've been working on this project for about a year. Maybe I'll get to fly it in a week or two. (continuing education, mandatory overtime, family)