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May 06, 2019, 06:02 PM
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clipper's Avatar
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Going to try 40degree total dihedral on a trial wing with out the kite. CG, yaw, etc will be the same. I hope it’s very stable so I can try and reduce the dihedral to 30 degrees instead. I’ll also know if I need more reinforcement at the nose and the motor mount.
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May 07, 2019, 12:12 AM
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clipper's Avatar
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Glued the carbon fiber tubing and flats and added the upper deck to help brace the dihedral and provide a method to support the motor mount.
May 07, 2019, 07:04 AM
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Timbo383's Avatar
Looking good.
Jun 03, 2019, 01:39 AM
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clipper's Avatar
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Starting to feel like progress. The elevens are attached the push rods are ready, just waiting for the servo glue to dry. Will attach everything for now and worry about lead dress after I find the CG. From my initial quick calculations, I found I had to mount everything at the nose. Hoping I don稚 need any extra weight. I already increased the size of the motor and battery slightly to help with getting the CG forward.
Jun 04, 2019, 08:35 PM
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clipper's Avatar
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Well, everything is mounted and I took a couple of short test glides. I found out a few things, one It痴 a little nose heavy which is good. I値l be able to move the receiver back behind the battery. Two, one of the tosses was to nose high and stalled on to a wing tip and did just fine. The third thing, I need a way to hold the plane when launching! Maybe I値l try a finger hole in the upper deck and launch under handed? The other would be to add two tabs underneath the wing to grab on to, I知 want to avoid putting holes in the bottom of the wing.

The all up weight is 213 grams or about 7.6 ounces. The motor can develope nearly 300 grams of thrust so I値l limit the throttle response for now which will keep the current draw well under 6 amps until I can get everything ironed out.

The next butterfly,I値l use a picture with the wings pointed more straight out and less forward. The CG will be farther back and will allow me to decorate with printed tissue paper over colored foam. Maybe I could find a way to print directly on the foam. I知 definitely dropping the idea of using a kite for the decoration; to heavy and not the best configuration.

Another thing that could happen, by making the wings light as possible, and just enough power, it could float around in a gym.

Looking forward to the next session of testing and flying.
Last edited by clipper; Jun 04, 2019 at 09:11 PM. Reason: Corrections
Jun 05, 2019, 05:50 AM
I Look, Listen, and Learn
Timbo383's Avatar
Glad to see that it's coming along good. On the launch you can try the sidearm toss....kinda like throwing a frisbee without the wrist twist....better to practice on a disposable plane first though. I've learned to use that method on flying wings and other pusher motor planes....that spinning prop scares me a little. You can Google it, there are vids out there of people showing how they do it.
Jun 05, 2019, 02:26 PM
IMO ( In My Opinion ) →
balsa or carbon's Avatar
Quote:
Originally Posted by clipper
The third thing, I need a way to hold the plane when launching! Maybe I値l try a finger hole in the upper deck and launch under handed? The other would be to add two tabs underneath the wing to grab on to, I知 want to avoid putting holes in the bottom of the wing.
This is how I do a side arm overhand frisbee launch :




"Literally" just a Flying Sheet of Dollar Tree Foam Board (1 min 13 sec)
Jun 05, 2019, 03:39 PM
I Look, Listen, and Learn
Timbo383's Avatar
It's more comfortable and natural feeling for me to do it just like throwing a frisbee underarm. There is no right or wrong way, just wich way you are more comfortable with. Clipper could practice either way with a sheet of papered dtf with a vert stab and balsa or carbon's cg location on his flying sheet.
Jun 10, 2019, 03:51 AM
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clipper's Avatar
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Thank you for your replies Timbo and BoC. I was hoping the 40 degree dihedral would be enough to give directional stability but it’s not. Ive added a temporary vertical stabilizer at least until I’ve worked out some ofthe other things I’m working on. First and foremost is to add some down thrust to keep the plane from looping back on me right after launch. I don’t even have time to put my hands on the controls and I’m ducking!

Timbo, once I get everything else ironed out, I’m going to try disc launch on this plane. I’ve launched planks but never something with dihedral. One step at a time.

Keep the help coming and thanks, Eric
Last edited by clipper; Jun 10, 2019 at 03:55 AM. Reason: Corrections
Jun 10, 2019, 04:58 AM
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Quote:
Originally Posted by clipper
I was hoping the 40 degree dihedral would be enough to give directional stability but it’s not.
If you're relying on the vertical projection of the wing area behind CG (via dihedral) to provide yaw stability, then it doesn't matter if you've got 10 degrees dihedral or 40. The relationship (between area forward and area aft) will always be the same until you move CG.
In your case you've got so much wing area up front that you'd need a VERY forward CG to get the yaw stability you're looking for via dihedral. Now, since you've got "looping on launch" issues, I'd say that alone dictates moving CG forward anyway (independent of thrust line issues).
If you get that CG forward enough, and keep some dihedral it may well be that you won't need a vertical stabilizer...
Jun 10, 2019, 09:16 PM
I Look, Listen, and Learn
Timbo383's Avatar
As to confirm nuteman's reply, on my chuck glider it needed alot...and I do mean alot....of weight up front to keep it from flipping. So, yeah, try to move that cg and try again.
Jun 10, 2019, 10:18 PM
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KenChin's Avatar
Depron RC Butterfly (1 min 35 sec)


10 Years Ago, i did this with Depron. Flown with 2S 850mah Lipo Packs. GWS Geared Prop (I think).


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