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Old Feb 05, 2013, 09:52 AM
Why kamikaze pilot wear helmet
mikes68charger's Avatar
United States, OH, Columbus
Joined Jul 2010
1,097 Posts
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How to find CG on a Delta wing?

Ok, I got a very sweet deal on a large Jet at a local swap meet. But the sellers could not even tell me the name of the manufactor of the bird.

All I know is the wings are 42in wide the fuse if fiberglass and its about 71in long.

I know this ant scrach built but it might as well be as I have no info to go off of.

So with a wing shaped like this how would I find the CG?

And as far a elvaon/airlone throws?

Thanks.

Mike
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Old Feb 05, 2013, 11:16 AM
Carbon fiber is our friend
Steve C's Avatar
United States, CA, Lodi
Joined Feb 2001
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I know what this is, but I can't think of the name. I'm looking through some old magazines for the ad and I'll let you know when I find it.
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Old Feb 05, 2013, 11:25 AM
Carbon fiber is our friend
Steve C's Avatar
United States, CA, Lodi
Joined Feb 2001
4,230 Posts
Well I guess I don't know what it is. I thought it was an R/C Kits F-106, sold by Hobby Barn in the 80's, but I think those are all wood. I always wanted one as a kid. CJM is 79" long, so that's not it either.

There have been a couple of 106's built here on the forum. I'd ask those guys for advise on cg. They'll get you close.
For throws, you're probably on your own, though I can tell you aileron dual rate is a good idea. When a delta is set up with enough servo throw for the elevator, the roll rate can be insane.
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Last edited by Steve C; Feb 05, 2013 at 11:45 AM.
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Old Feb 05, 2013, 11:50 AM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
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http://en.wikipedia.org/wiki/F-106_Delta_Dart

http://f-106deltadart.com/

http://www.nationalmuseum.af.mil/fac...eet.asp?id=389
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Old Feb 05, 2013, 01:43 PM
Why kamikaze pilot wear helmet
mikes68charger's Avatar
United States, OH, Columbus
Joined Jul 2010
1,097 Posts
Thanks I new found out it was a Delta Dart 106 wich is sweet. But I was hopeing for the manufacture of the kit, as the body is fiberglass so it was not stick built.

I thought it was Jet Hanger Hobbies, but the intake ducting is more like Jet Centry Modles, but it don't have the air brake.

I found a CG caluclator, but its complicated as the wings do not come to a point so Im a little lost.

Thanks Mike
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Old Feb 05, 2013, 01:58 PM
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Mike,

just build a non RC glider made from balsa, scaled down to a wing span of 12 inch. Including elevator and fuselage. You don't need any wing profile, just a flat balsa sheet. But you have to mount a scale vertical fin for vertical stability.

The CG you find by this method you can transform to your model by scaling up to your size. But for safety reason I always go 0.5 inch more to the front for the maiden.

That method works in all cases of wing shape. Standard, only wing, delta etc. better than any calculation program!

Heiner
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Last edited by heiner; Feb 05, 2013 at 02:04 PM.
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Old Feb 05, 2013, 02:44 PM
Build it and it will fly!
Ken Wright's Avatar
Canada, AB, Okotoks
Joined Feb 2003
125 Posts
This might help you: http://www.adamone.rchomepage.com/cg_canard.htm
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Old Feb 05, 2013, 02:47 PM
Build it and it will fly!
Ken Wright's Avatar
Canada, AB, Okotoks
Joined Feb 2003
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This might be closer to what you're looking for; I just couldn't remeber where I saw it last...lol!http://www.moleski.net/rc/WingMAC.htm
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Old Feb 05, 2013, 03:44 PM
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North Britain
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This is a good programme for unusual shapes as it allows you to include the fuselage. As heiner says, verify the result with a chuck glider.

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Old Feb 06, 2013, 12:04 AM
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LuvEvolution7's Avatar
St.Catharines, Ontario
Joined Jan 2009
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you CG

here's your CG
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Old Feb 06, 2013, 12:14 AM
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St.Catharines, Ontario
Joined Jan 2009
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this is exactly the same shape as our Chimera jet and this is how we came up with the CG as per instructions from Brent (Corsair Nut). it is still 25% of MAC. the final CG ended up being 26% of MAC and it flies well at that CG. since the two planes are alike in shape, I would start at the 25% MAC point and you can always move rearwards if you need to, like we did.

Rich
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Old Feb 06, 2013, 12:17 AM
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St.Catharines, Ontario
Joined Jan 2009
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the problem with a flat plate, delta chuck glider, is that it gives false results, as I found out with the Chimera. I made one and after many, many tests, I found the best results were at 43% of the root chord. as you can see in that thread, the results of the chuck test and the actual flying model were very different. if we'd have flown at the 43% root chord mark, we would have been severely tail heavy.
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Old Feb 06, 2013, 10:48 AM
Why kamikaze pilot wear helmet
mikes68charger's Avatar
United States, OH, Columbus
Joined Jul 2010
1,097 Posts
Wow thanks, that helps a ton!!

I had a Balsa North Star with is a delta with little elve, and I new the CG was pretty far foward. But this is good new as my 12 lipos will not be that far foward of the CG !

I think before I spend a ton of time repainting it, Im going to fly as it first.

I just wish this snow would go away.

Im have a Knife Liddle 4.5in EDF fan with 15 pound thrust made for this bird, and if my math is close it will be in the 12.5 pound range when done.

Should be fun.cool:
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Old Feb 07, 2013, 12:12 AM
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St.Catharines, Ontario
Joined Jan 2009
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Lee's stuff is awesome. you'll be happy with it in that plane. it'll put a BIG smile on your face.

and you are very welcome for the CG. always happy to help.

Rich
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Old Feb 07, 2013, 11:02 AM
Carbon fiber is our friend
Steve C's Avatar
United States, CA, Lodi
Joined Feb 2001
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Quote:
Originally Posted by LuvEvolution7 View Post
the problem with a flat plate, delta chuck glider, is that it gives false results,.
I used one for my delta and it gave me a safe cg to start with. I did throw it around quite a bit to make sure it recovered from high angle throws and various speeds.
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Last edited by Steve C; Feb 08, 2013 at 11:58 AM.
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