Scratch build/design 1/2a Delta
#1
Scratch build/design 1/2a Delta
Hi Guys, I've got a pile of foam and a hot wire cutting rig. A couple of Sure Starts laying around, and the transmitter and guts from an Aerobird Challenger plane just looking for a home. I always wanted to put together a Delta, and thought as the Aerobird is a V tail set up, the gear would work just fine in a small Delta application. Now, never building or flying one, what kind of airfoil should I use. Semi or full symetrical? How big to I have to make the vertical stabilizers for say a 30 to 36" wingspan? And, how the heck do you figure out where the CG would be? Any info and input would be greatly appreciated!! Thanks, Prop
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RE: Scratch build/design 1/2a Delta
ORIGINAL: propbuster
what kind of airfoil should I use. Semi or full symetrical?
what kind of airfoil should I use. Semi or full symetrical?
ORIGINAL: propbuster
How big to I have to make the vertical stabilizers for say a 30 to 36" wingspan?
How big to I have to make the vertical stabilizers for say a 30 to 36" wingspan?
ORIGINAL: propbuster
And, how the heck do you figure out where the CG would be?
And, how the heck do you figure out where the CG would be?
The big one has an airfoil, the little one doesn't, it flies faster and slower than the big one with the airfoil, out of sight in 5 second straight up, 58,000rpm.
PS the little on is landing, not climbing.
#3
RE: Scratch build/design 1/2a Delta
Thanks for the info Soarrich, and nice looking birds! I've decided to go with an NACA 63-015A symetrical airfoil and plotted and printed it out for the core templates. It's a 15" chord tapering down to 4" at the tips in 15", for a total of a 30" wing span. It's plenty thick at the root, about 2" (maybe too thick?) so I'll have plenty of depth for the gear. I thought I'd put some kind of canopy and deck on top also. The 3x5 fins should work out nice too and I'll just shape them to fit the overall look desired. About your models, is the little one a ducted fan? I don't see any prop or power plant. I'm planning on using a SureStart in a tractor configuration. I also have a big fiberglass fuselage Delta (.40 size) that's been put on the back list of projects to complete! If I can ever get my new shop completed.........
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RE: Scratch build/design 1/2a Delta
Prop, that's too big for a surestart. The Blink is 18" span and the Lil Streak is 28" span. The Blink is almost unlimited with a SS while the LS wouldn't break ground with one. Personally, considering the medium (foam) I'd go with something around 20". That's assuming an actual delta shaped planform. A delta usually is an isosceles right triangle, ie, two equal legs that would be the leading edges and the third side or trailing edge would be twice the length of either leg. I doubt like heck that you'll ever find that definition in a dictionary, but somewhere along the line it became a standard of sorts and hopefully made it easier to communicate the sizes.
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RE: Scratch build/design 1/2a Delta
Your yellow and black delta is cool!
No ducted fan, just a 3x3 prop with 25 amps through it, I have to slowly give the power or the prop hub just melts off.[:@] You can see the little black prop in the back. All the wires hanging out was to get them away from the power lines to the motor, without that when I gave it power the radio went nuts.
No ducted fan, just a 3x3 prop with 25 amps through it, I have to slowly give the power or the prop hub just melts off.[:@] You can see the little black prop in the back. All the wires hanging out was to get them away from the power lines to the motor, without that when I gave it power the radio went nuts.
#6
RE: Scratch build/design 1/2a Delta
Patrick, Yeah, I was thinking that it might be a wee big for the SureStart to haul so, I'll re-plot and print the templates smaller! If I'm thinking right, For a 20" wing span, the chord would be 10" at the root and the half span 10" also for a right triangle. Instead of the expanded white foam and sheeting it, I thought I'd use the blue extruded stuff for strength and just cover it with low temp iron on.
Soarrich, I don't know much about "leckys" but 25 amps with a 3x3 sounds like a lot! It looks sharp. The picture of the yellow and black Delta is a prototype and although I've got the templates ready,I haven't even cut the wings for mine yet. As soon as I get my shop together I'll be making a plug from the fuselage to pull copys from.
Soarrich, I don't know much about "leckys" but 25 amps with a 3x3 sounds like a lot! It looks sharp. The picture of the yellow and black Delta is a prototype and although I've got the templates ready,I haven't even cut the wings for mine yet. As soon as I get my shop together I'll be making a plug from the fuselage to pull copys from.
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RE: Scratch build/design 1/2a Delta
soarrich-
Just wondering what motor your little delta has that uses a 3x3 and can handle 25amps. That's pretty impressive...
Just wondering what motor your little delta has that uses a 3x3 and can handle 25amps. That's pretty impressive...
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RE: Scratch build/design 1/2a Delta
Prop, about the fins, if you go with a wing planform like your yellow/black version, it doesn't require as large a fin. I've done a lot of experimenting with the delta fins, so once you get it laid out, let me know. I can probably give you some good info on sizing it. One thing I did find was that it's nearly impossible to make it too big. Too small was pretty easy and usually resulted in a nice flat spin shortly after release.
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RE: Scratch build/design 1/2a Delta
propbuster
ptulmer is right about the delta shape, what you're making is more a flying wing. If you go with a flying wing you need a good airfoil, S5010, S5020, BW050209, or Simitar1 are good choices. I've built flying wings using all, the S50xx are flat bottomed and easy to build with ribs, the BW is the best IMHO, the Simitar1 is the most used and worst[:'(]
ptulmer is right about the delta shape, what you're making is more a flying wing. If you go with a flying wing you need a good airfoil, S5010, S5020, BW050209, or Simitar1 are good choices. I've built flying wings using all, the S50xx are flat bottomed and easy to build with ribs, the BW is the best IMHO, the Simitar1 is the most used and worst[:'(]
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RE: Scratch build/design 1/2a Delta
[8D]Heeeey, slap both Surestarts on that thing and it'll probably handle the 30" span just fine. And the cool factor.......well it would be way out there, as would the difficulty of getting them both running right! Anyway, Are you doing a true flying wing, or will it have vertical tail surfaces? If you want to try the true wing, stop by nurflugel.com. I built one and the information here is invaluable. Are you considering a pusher configuration or a tractor? All of this is pertinent. They do have some nice wing cross sections. The one I used was a flat bottomed foil, with a good amount of dihedral and washout. I have a OS .40 in mine (its not a 1/2-A) and it flies really nicely. One thing I discovered with my version is that the thicker the airfoil, the bigger the elevons have to be to retain effectiveness. This is important as they act as the elevator too, and I cant tell you the difference in improved flying chracteristics increasing these after the first flight made. Also, if you are doing a swept wing, the CG ends up being further back than you would think. Anyway, good luck!
ZZ.
ZZ.
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RE: Scratch build/design 1/2a Delta
Sorry, missed a part of your post. Looks like you said a tractor config. Still think two Sure starts would kick butt.[>:].....evil grin.
ZZ.
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RE: Scratch build/design 1/2a Delta
Nothing is worse than a maiden voyage where you have run out of down trim and have to fly the whole tank out with forward thumb pressure to keep the plane level. I would just dial it in 0-0, the amount of up trim needed is hard to measure, if you get the CG located properly. Yes, thick airfoils need flaps with more chord.