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Author Topic: Whirlygig 30  (Read 600 times)
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Maxout
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« on: October 03, 2010, 01:10:05 PM »

Here's my latest glider. A pretty simple one, 30.5" flat span, carbon reinforcing in appropriate areas, etc. I'm averaging 35-55 seconds, but have yet to fly it in calm weather, so I have no idea what dead air performance is for this critter. It's been a while since I've done tip launch, and I'm really bad at it right now. Trimmed this bird out in 15 mph winds...fast DT was a real asset and prevented some ugly crashes. Did get it out on a very thermally day last week and saw a lot of nice long flights. With a sink rate of less than 1 1/2 ft/sec, it doesn't take much to keep this one up there.

I think I put about 5 hours total into building it...came out nicely considering!

Has anyone considered using a torsion spring to pivot the tailboom? I'm starting to think you could get rid of a noticeable amount drag by not having that assembly going on at the wing root.

Also, what are folks doing to get carbon tow to lie down nice and flat on glider wings? I got some of it to come out ok, but some did not. Or should I just glass the left wingtip instead?
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Whirlygig 30
Whirlygig 30
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Hepcat
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« Reply #1 on: October 03, 2010, 03:52:30 PM »

Josh
The 'Whirlygig' looks like a Maxout aeroplane, which is a term of praise nowadays! I must say though that the tailboom does look very thin and I shall be interested if you have any comments about it when you get your arm in practice again.

I too dislike the appearance of the stuff for urging the boom up on D/T and I have been looking at a torsion spring for my CLGs but so far nothing seems to be just right.
John
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Maxout
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« Reply #2 on: October 03, 2010, 10:09:27 PM »

Yeah, I reckon the boom is rather skinny... 3/16" OD thin wall tube. It seems plenty strong, although we all know that a tapered tube would be better. But it seems to do fine. Haven't noticed any tendencies indicative of twisting under launch stresses.
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sweepettelee
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Simplicate & add more lightness. Keep sanding!



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« Reply #3 on: October 03, 2010, 11:27:49 PM »

Maxout, [Josh?],

Your TLG looks like it will do the job.

BTW, I wonder if you saw the "Tip Launch Glider" section just down the HPA listings? If you were to peruse the batch of postings you might find most answers to your queries.

Re gluing carbon tow straight & flat: some give the tow just the lightest spritz of 3M 77 on non-stick paper, then apply with favorite glue [cyano, epoxy or Duco-type]. I suggest you Duco on some light f-glass to assist locking it in place for the long term.

FYI, I have not added carbon to my TLG grip area, just f-glass layer top & bottom with Duco or equiv.

Just dot the area with the glue, lay the f-glass on and quickly brush on MEK to blend and flatten things out. I 'squeegee it' with a dowel, but do not roll it, or the f-glass usually lifts. Then I pat down the wet spots with blue paper towel pieces. The nitrocellulose glues suck the fibers of
the f-glass nicely to the balsa.

Some use thin cured carbon strips and cyano to strengthen the tips.

Leeper
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Zack
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« Reply #4 on: October 04, 2010, 08:23:40 PM »

Great looking glider!

I've used torsion springs for deploying helicopter recovery blades for model rockets, as well as rocket gliders using variable incidence for recovery. It does have the significant advantage that the spring will still work in very cold weather.

Zack
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Rewinged
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« Reply #5 on: October 04, 2010, 09:48:15 PM »

Looks great, Josh.

Regarding the DT force, I've pondered putting a groove in the pivot block, and recessing both hooks and a groove at the wing root for the rubber. But I am doubtful it is significant drag, worth even 1 second of flight time. But you are more knowledgeable about the drag than me, do you have some idea of the potential benefit?

--Bill
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Tmat
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« Reply #6 on: October 04, 2010, 10:30:56 PM »

Ok,
My take on the spring versus rubber band is that it's not worth worrying about the drag issue. These are thermal gliders not indoor gliders. The ease of replacement of a rubber band would outweigh the potential benefits of drag reduction (and with the rubber band located in the area where the wing is in turbulent flow the benefit would almost certainly be small indeed).

But if it is something that turns you on then have at it by all means!

Nice looking glider!

tony
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