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Old Nov 07, 2014, 10:43 AM
Formosa/VH EPP Thundebolt/UMXR
snoking's Avatar
United States, WA, La Conner
Joined Jan 2013
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Will it fly - Home built flying wind

Well yesterday is was raining and blowing very hard, so I built this from "things" in the shop/garage.

It is made out if coroplast that I had left from another project on the boat.

http://www.coroplast.com/

The wing is two layers of coropast with a wedge near the leading edge to form a bit of an airfoil. The battery picture is a 2s 450 Nano-tec. Weight is 24 oz with this battery. I have 3s 1300 that worked with this power train in a Ares Gamma 370 Pro, which will add more weight, and require a switch to Deans connectors. Setting it up on my new DX6 was fairly easy.

Any suggests on CG and maidening it? How to launch it? Sling it? At 48" should I clip the wing length a bit?

http://s269.photobucket.com/user/sno.../Flying%20wing

Chris
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Old Nov 07, 2014, 11:41 AM
Formosa/VH EPP Thundebolt/UMXR
snoking's Avatar
United States, WA, La Conner
Joined Jan 2013
297 Posts
Looks like CG is way aft. May clip WL to 34" and recheck. Chris
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Old Nov 07, 2014, 03:14 PM
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Originally Posted by snoking View Post
Looks like CG is way aft. May clip WL to 34" and recheck. Chris
What method did you use to determine the correct cg position? Does WL in your post refer to the wingspan? Normally, the correct cg is obtained by moving the equipment around, but if changing the planform will achieve that while maintaining the desired wingloading, I don't see why not. You will be giving up a bit of aspect ratio, which may or may not be important in the intended role for the airplane.

Good Luck!
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Old Nov 07, 2014, 08:11 PM
Formosa/VH EPP Thundebolt/UMXR
snoking's Avatar
United States, WA, La Conner
Joined Jan 2013
297 Posts
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Originally Posted by DT56 View Post
What method did you use to determine the correct cg position? Does WL in your post refer to the wingspan? Normally, the correct cg is obtained by moving the equipment around, but if changing the planform will achieve that while maintaining the desired wingloading, I don't see why not. You will be giving up a bit of aspect ratio, which may or may not be important in the intended role for the airplane.

Good Luck!
My brother "Jet_Flyer" sent me this link! Chris

http://fwcg.3dzone.dk/
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Last edited by snoking; Nov 08, 2014 at 12:31 AM.
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Old Nov 08, 2014, 06:24 AM
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United States, WA, Moses Lake
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Plug all your numbers into that calculator. The tip measurement should include the aileron width, the root should not. Since its already built I would lay a straight edge from the leading edge of the two wing tips and measure up to the nose to get my sweep distance. Just looking at it I'm guessing 6.5 to 7.5 cg range. Even with your 1300 battery its going to be tail heavy. I've smashed fishing weights and taped it to the nose. cg is critical.

Don't worry about the weight that wing is big enough to fly a six pack if the motor has enough power. You can't fly a tail heavy wing no matter how light it is. The best way for me to launch a wing is the overhead toss. I've done the sidearm but its harder for me. Check this out

The Best Way to Launch a RC Wing (2 min 15 sec)
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Old Nov 08, 2014, 08:09 AM
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Here is the calculator I use its nice but notice it goes by panel length instead of wingspan its half the wingspan but the two calculators the cg comes out the same as the one you have although this one draws the measurements also http://j.mp/TRg1cb

You notice my wingspan is less than yours and almost the same weight with a 2200 battery in a pod cause to balance it about half the length of the battery was sticking past the nose. I know its instinctive to not add weight, but do it anyway! You will probably need a couple ounces of lead on the nose but fear not that big wing will fly like a dove if you balance it right. I don't know why I launched mine the way I did in this video the overhead toss is much better.

Don't forget to give it some up trim about 1/8 inch or so on the elevons and it should fly something like this

TSW v2 (5 min 55 sec)
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Old Nov 08, 2014, 08:54 AM
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United States, WA, Moses Lake
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Good on you Snoking for scratchbuilding a wing. I can't think of a better way to recycle parts from wrecked airplanes. It's a no brainer. They are a blast to fly and cost almost nothing to build. I've built seven so far out of dollartree foamboard, Armin wing types and kf4 types they all make me brave so eventually I wreck them or wear them out.

I like the big wings better than the smaller wings they aren't as twitchy. I have my throws about 3/8 up and 1/4 down you really don't need anymore travel than that. I'd like to know how the maiden goes!
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Old Nov 08, 2014, 09:33 AM
Formosa/VH EPP Thundebolt/UMXR
snoking's Avatar
United States, WA, La Conner
Joined Jan 2013
297 Posts
Low and Slow

Here are some new numbers based on your input:

Root Cord 15
Tip Cord 6
Sweep 16.5
Wing Span 48

CG at 20% 9.3"

Both Calculators come out the same. Thanks for the trim suggestions!

I have stick on weights from my Losi Speed T that I race on a paved oval in a Snowbird park in Arizona. So I will put it on the stand and balance is this morning and maybe give it a try.

I have to watch out for prop strikes, as I am on a blood thinner! So launching it is a concern!

Thanks Chris
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Old Nov 08, 2014, 10:29 AM
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I don't know what you have for a motor thrust wise but give it enough throttle so its pulling good against you but not so much that its bucking , I use about 1/2 throttle. I'm using a 2215 motor pulling 19 amps with an 8x6 prop. Once you get used to launching these things they are a hoot to fly. I'm going to fly mine right now, I have forty acres across the street from my driveway!
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Old Nov 08, 2014, 10:43 AM
Formosa/VH EPP Thundebolt/UMXR
snoking's Avatar
United States, WA, La Conner
Joined Jan 2013
297 Posts
It is a 1250KV motor from my old Hobby Town Ares Gama 370 Pro airplane. Have a 8x6 show fly prop on it with a prop saver. I have not put my amp meter on it yet, but will. I have both 25C and 35C 3s 1300's.

Chris
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Old Nov 08, 2014, 11:05 AM
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United States, WA, Moses Lake
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Hey maybe instead of lead weights try running the batteries in parallel and using two batteries? I mean as long as you need the weight anyway might as well use a bigger gas tank right?
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Old Nov 08, 2014, 12:25 PM
buyer of the farm
United States, FL, DeLand
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Also watch the winglets. They are NOT supposed to point perfectly in the direction of travel. If they do they will do nothing to keep your plane from yawing. They need to have some toe-in. My approx 5" long winglets are toed in about a quarter inch on each side. This way when the wing yaws the leading winglet has more drag than the trailing one, straightening out the plane.
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Old Nov 08, 2014, 01:35 PM
Formosa/VH EPP Thundebolt/UMXR
snoking's Avatar
United States, WA, La Conner
Joined Jan 2013
297 Posts
I am having a real hard time understanding this. In this picture the CG according to both formulas comes out at the rear of the yellow ESC. It is going to take whole lot of weight to balance it at that point!!! Chris

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Old Nov 08, 2014, 04:03 PM
Go Dawgs!!!!!!!
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Originally Posted by Rockin Robbins View Post
Also watch the winglets. They are NOT supposed to point perfectly in the direction of travel. If they do they will do nothing to keep your plane from yawing. They need to have some toe-in. My approx 5" long winglets are toed in about a quarter inch on each side. This way when the wing yaws the leading winglet has more drag than the trailing one, straightening out the plane.
Totally untrue, I have several wings from different designers and NONE have towed in winglets, all fly just fine. They simply act as a vertical stabilizer, towing them in would only add drag and slow the wing down
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Old Nov 08, 2014, 07:08 PM
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I am having a real hard time understanding this. In this picture the CG according to both formulas comes out at the rear of the yellow ESC. It is going to take whole lot of weight to balance it at that point!!! Chris

Well yeah it will. Think of it as a seesaw with the pivot at the cg line. You've got the motor weight +servos + 2/3 of the wing behind the pivot so you need a lot of weight forward to balance it. The only thing you can do is move the motor and servos forward closer to that cg pivot point (receiver too) or add a lot of weight forward. Put that second 1300 cell beside the one on the wing and see what happens. Or use the dune buggy weights. Or chop out the center so you can move the motor forward an inch or two. That would be a hassle at this point so pile the weights on there it will fly fine. You have enough wing area on that to fly a lot of weight, guys add camera gear to most of them that size but I'm not brave enough to put my canon on mine I'd go with lead instead or a huge battery. In my case moved the battery forward of the wing in a pod.

See the silver sharpie line near the yellow tape in the bottom of my wing, that's the cg line
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