Lumenier RB2205C-12 2400KV SKITZO Ceramic Bearing Motor
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Old Dec 10, 2008, 04:17 PM
cjbucher is offline
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Hmmm. I haven't had that problem. I did the normal 1/4" blue cor with a top and bottom piece. Somehow that hollow shape along with the spar and some bamboo skewers made mine very rigid. My power system gets my plane to around 65 mph in level flight and up to 80 in a dive. Never had a flutter.

It's weird how the 1/4" foam is so flexible but when you put 2 pieces together with a spar in the middle, it becomes quite rigid. Must be an engineering principle in there somewhere...

Maybe solid foam allows for a lot more flex?

---

I also built an "Ultron" 3D plane that's a full fuse design. Amazingly strong and rigid design. Love the way it flies. https://www.rcgroups.com/forums/show...ghlight=Ultron
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Old Dec 10, 2008, 07:59 PM
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thanks heaps guys..
hmm im a little worried about too high an amp draw as the battery is a standard pack out of a honey bee king 2..so its only rated for 10c at 1000mah...could it cope with the 4.75x4.75?
ill probably have to pick up another pack anyway so wat sort of mah and discharge rate are we talking?any suggestions on a cheap source?
sorry for all the q's..bit of a nub wen it comes to lipo tech etc..
cheers,
matt
Old Dec 10, 2008, 08:16 PM
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Quote:
Originally Posted by smkn951
what to do to get rid of flutter.
i have cf across already, taped leading edge. but at 10 seconds into a level ft flight it'll vibrate and flutter.
power is donsrc wicked jr, 3s 1300, 30 amp esc.
any suggestions on making it stronger? fg i have melted the test foam i have
BTW its made of 1/2 blue cor sanded to an airfoil.
TIA
one thing that i hav found in the past with planes and wings wen i have tried to shape them myself is that unless the wings are very very similar in shape, which is hard to do wen jus sanding and checking it by eye, that the wings will "flutter" in flight.. im not second guessing ur build quality, jus explaining wat has happened to me before..
one other thing...take a sheet of paper for example...hold it out flat and it will bend and flop down...do the same thing again but this time put a curve or "arc" in it wen u hold it...much more rigid and it doesnt flop..i think this applies to the wings that use 2 sheets with a spur as they have the same curve built in the design hence making it much more rigid...

matt
Old Dec 11, 2008, 10:49 AM
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Quote:
Originally Posted by more_eggs
thanks heaps guys..
hmm im a little worried about too high an amp draw as the battery is a standard pack out of a honey bee king 2..so its only rated for 10c at 1000mah...could it cope with the 4.75x4.75?
ill probably have to pick up another pack anyway so wat sort of mah and discharge rate are we talking?any suggestions on a cheap source?
sorry for all the q's..bit of a nub wen it comes to lipo tech etc..
cheers,
matt
10c 1000mah really can only handle 10 amps. You might get away with the 4.75x4.75 but try not going full throttle too often. In any case, that battery will age fast.


Quote:
Originally Posted by more_eggs
one other thing...take a sheet of paper for example...hold it out flat and it will bend and flop down...do the same thing again but this time put a curve or "arc" in it wen u hold it...much more rigid and it doesnt flop..i think this applies to the wings that use 2 sheets with a spur as they have the same curve built in the design hence making it much more rigid...

matt
Um, that's what I said.
Last edited by cjbucher; Dec 11, 2008 at 10:54 AM.
Old Dec 12, 2008, 10:53 PM
in2skimn is offline
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in2skimn

blue core wings


Quote:
Originally Posted by cjbucher
10c 1000mah really can only handle 10 amps. You might get away with the 4.75x4.75 but try not going full throttle too often. In any case, that battery will age fast.




Um, that's what I said.
guys hears a great site that help me with my 32" wings.http://home1.gte.net/texhills/page3.html
easy instuctions. any guestions feel free to ask.
chuck
Old Dec 24, 2008, 02:45 PM
j4ck4 is offline
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My Wing


Hey jI just maidened my first attempt at building a wing. With a few tweaks on my cg I got about an 8 minute flight out of it in 38 degree weather with variable winds of 6-15 mph all over the compass.
This is the first scratch build I have flown, just got started building a couple weeks ago and I love it. You guys keep the good build threads comming.
Old Dec 24, 2008, 11:45 PM
sketchanderase is offline
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new pic, same plane....
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looks cool, ill try one when i have time...
Old Dec 29, 2008, 10:00 AM
FASTBEN is offline
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well my 32"first flight went well yesterday,great flayer i had used a BP 21 out runner on this one with a cut down 10x4 prop to 7x4 @ 3 1/4 throttle the wing would take off from a vtol position from ground but @ full stick in the air it will do about 30miles max very smooth but speed is not what i was looking for i had a 3s 2250 25c it only pulls about 17amp the plane is 1lb even and i did not thing my JGF 350 would do the job.so back on the drawing board to see if i can figer dif motor.
ben
Old Dec 29, 2008, 12:42 PM
Murman is offline
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Quote:
Originally Posted by FASTBEN
...used a BP 21 out runner on this one with a cut down 10x4 prop to 7x4
Most of the thrust from a prop comes from near the tips. When you cut 3" off of your 10x4 you eliminated most of the "sweet spot" on the prop. If I were you I would find a true 7" prop to try before you give up on that motor.
Old Dec 29, 2008, 02:21 PM
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you are abselutly correct i will do it and try,
ben
Old Dec 29, 2008, 04:36 PM
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I agree don't cut the prop. IT will for sure not preform right at all. I have tried it. Not good.
Last edited by More Trim; Dec 29, 2008 at 07:51 PM.
Old Jan 02, 2009, 01:33 PM
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I'll be running a 2408-21 on mine in puller config using a 1500mah 3s (20c) battery.
What size prop would you suggest?

here' some pics of where we are now... 32" ws just like the original plans.
Old Jan 02, 2009, 03:18 PM
Wrench66 is online now
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Chino Renegade oh-gee, yo
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Quote:
Originally Posted by pburt1975
I'll be running a 2408-21 on mine in puller config using a 1500mah 3s (20c) battery.
What size prop would you suggest?

here' some pics of where we are now... 32" ws just like the original plans.
Hi PBurt,
That BP21 has a pretty good following in our club.....lots of them running in the 7x5 area with great thrust and decent run times (using about the same mah battery you have there) of 7-8min. Use at least a 25a speed control or can drop to a 20 IF you have good thr management skills (I do not).
Most the planes and wings we fly are in the same weight class as your wing so this should help

--Ray
Old Jan 02, 2009, 04:00 PM
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Hey that thing is pretty sweet. Did you go by some sort of plan. And is it something can get?





Quote:
Originally Posted by pburt1975
I'll be running a 2408-21 on mine in puller config using a 1500mah 3s (20c) battery.
What size prop would you suggest?

here' some pics of where we are now... 32" ws just like the original plans.
Old Jan 02, 2009, 06:10 PM
Murman is offline
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Quote:
Originally Posted by pburt1975
I'll be running a 2408-21 on mine in puller config using a 1500mah 3s (20c) battery.
What size prop would you suggest?
The ep8040 is my favorite prop for that motor on 3s.
Here is some great prop data for the bp21.


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