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Old Jan 18, 2005, 06:36 AM
gpw
“There’s no place like Foam”
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Joined Jul 2002
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That is somewhat confusing (the basic principle ) cause' logic would want to argue that they should move like elevons(twisting the tail for turn???), which we now know is wrong ....so much for thinking ....or not ....hahahahahaha Well put Gbond!!!!

I think I might have to build one for the ips motor...just for fun .....a little vertical in the gym couldn't hurt ....hahahahaha
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Old Jan 18, 2005, 09:34 AM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Yes, I got confused between V-tail and tailevons.... once Ouch!
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Old Jan 18, 2005, 10:33 AM
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robbie's Avatar
Barsoom
Joined Jan 2004
288 Posts
is this correct?
the motor is the 7.2v twin ips
so the gearing is s1 gearing 4:1 and i am using a 8x6 prop
on 7 cells it is drawing 3.9 amps and generating 219 grams of thrust (over 7oz)
so when i was trying to run it on a 150 mah nimh pack
3900/150=26
i was asking the battery pack to discharge at 26c?

a 700mah lipo pack weighs about the same
3900/700=5.6 (rounded up)
so 5 or 6 C is a more reasonable request.
so on the higher capacity lipo pack, the same motor will draw 3 amps instead of 4 (less wear and tear on the motor?) and still provide almost 1:1 thrust/weight ratio at 6oz. and the wings are still lightly loaded for slow flight at around 4oz.
-robbie
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Old Jan 18, 2005, 11:42 AM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Sounds like a winner, robbie

Yes, typical IPS runs at 2A/motor. The IPS-D should be around 4... The 150mah pack is marginal at 2A, dismal at 4A! Sounds like the right application for 6c 2s700's, or 10c 2s480-520's. They are about the same weight, and I consider them in the same class. Haven't measured run time at 4-5A, but I bet it's closer than the 500/700 rating would have you believe.
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Old Jan 18, 2005, 08:14 PM
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STRINGFLY's Avatar
Little Rock Regional, Arkansas, United States
Joined Sep 2002
4,453 Posts
Gym-blu

Neat Gene.... printing them out now... Have a indoor fly this weekend and will try to work one up. Have lots of 3D stuff to fly but since I don't get to fly hardly at all indoors, will probably tear up all my 3D stuff. This one should just keep flying on and on. Will use some depron.......but have some blue too. Will let you know how it does.... Thanks for the plans. STRINGFLY <>++++
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Old Jan 18, 2005, 09:55 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Sounds like a plan, String. Just remember, 'Light is Right'... Maybe you'll have a sub-4oz one?

Take some spare foam with you (or use some bits off the floor ) to play with the wing incidence. Try a couple different shims here and there, and let me know what you think. I started at 2 degrees, I revised it to 2.5 degrees (3/8"), and I'm currently flying at 3.5 degrees (1/2"). Next calm night, I'm going to try 5 degrees (3/4")...
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Old Jan 18, 2005, 11:31 PM
Why aren't you out flyin?
colbyweb's Avatar
Overland Park, Kansas, United States
Joined Mar 2004
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Gene, since you've been playing with the incidence, what do you recommend now? If it's 3.5 degrees I'd like to just build it in from the beginning. Oh I guess I forgot to mention, I'm building another one, the first wasn't worth fixing I'm not going to be -quite- so weight concious this time. I think if I can keep it at 5 oz or so it should be fine.
-Rick
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Old Jan 19, 2005, 05:52 AM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Rick: I'm liking the 3.5 degrees right now, witch is another 1/8" higher in the front than the current plans call for. Notice, though, it will cause some climb under power. However, I feel the slow speed stability is worth it. It's one of those balance issues that are going to be dependant on power and speed. I glued a shim in place in the front pylon to add the extra length.
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Old Jan 19, 2005, 08:10 AM
gpw
“There’s no place like Foam”
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Tried the more incidence thing , more draggy on the tiny LPS motor ... maybe 'a limit on the good thing ....especially with minimal power .... mine flies good anyway with only the original shim (TOF)...pretty slow now...Grandma'could fly it....well, you know!!!
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Old Jan 19, 2005, 12:39 PM
Why aren't you out flyin?
colbyweb's Avatar
Overland Park, Kansas, United States
Joined Mar 2004
2,046 Posts
I'm using a cdrom motor with plenty of power so I think I will take Gene's advice. Should have it finished today, too bad I didn't work on it more yesterday since the weather is almost perfect today. Maybe I can finish it soon enough to go fly it before the day is over. Thanks
-Rick
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Old Jan 19, 2005, 02:37 PM
2^p - 1
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United States, MO, Springfield
Joined Feb 2003
1,326 Posts
Finally maidened mine. I've had a hard time keeping quiet--i take the 'never post until the maiden' approach.
Made a few changes, mostly to adapt to a CD rom motor and 3s lipo. I also used a wing & tail design that i've been messing with for another design. All in all it flies even better than i had hoped. This was my first VTail, so i didn't know what to expect. It's a great front yard touch & goer.

the rundown:
30" WS, 6oz AUW, 3s 520, 17T CD rom (more power than necessary, but why not?)

I'll take a pic tonight, but here's a jpeg of the plans. With Gene's approval, I'd be happy to post them in any format you guys want.

-scott

Thanks Gene!! Great design!
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Old Jan 19, 2005, 10:21 PM
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Little Rock Regional, Arkansas, United States
Joined Sep 2002
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Gym-Blu

Working on my Gym-Blu...... mine is white depron... so..... Gym-whit...(dim-wit!!! he he.........) Added a inch to the span.... foam was 29 inches wide......... using a neat Avia Breeze wrapped carbon spar I had laying around from my low wind, no wind hi-tech kites for the fuse stick,,, very light but very strong. Hope to finish up before the indoor fly this weekend. I have raised the leading edge a bit, per Gene. Hope to get under 5 ounces. I have some 250 and 340 2 cells. STRINGFLY <>+++++
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Old Jan 19, 2005, 11:18 PM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
Gym-Ron???

Looking good! My Depron wing was 27.5", since that's the size I had It needs reinforced, or a lighter load, though That spar is probably the hot ticket. IIRC, the 3/16sq spruce stick I had was 3.3g... The 1/8" CF tube I have would be 2.5g... A light wrapped tube, rather than pultruded might be 1/2-2/3 of that weight.

SF: Go for it! Variations are welcome. I was just using the easy way out The tapers rob a little wing area, so you might want to cheat the chord some to make up the difference.
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Old Jan 20, 2005, 06:26 AM
gpw
“There’s no place like Foam”
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Joined Jul 2002
23,988 Posts
I have a question for my motor GURU.... Gbond, would it be better to run an 8x4 on the ips (white gear )...just a little more thrust would do for me....
Another question ... when do we build the j250/D version ...Twice as big ??? Dome-Blu...???
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Old Jan 20, 2005, 07:26 AM
Crash Master
Gene Bond's Avatar
Indianapolis, IN
Joined Sep 2001
16,632 Posts
GPW: I think you said you are running LPS-B2C-C Look right?

I'd try an 8x4.3 prop on it myself. IIRC, that's the setup I loved on my PicoPiper and my Butterfly. They were both sub-5oz, as well, running the 2s250's.

I'll have to dig that one out to try on the 'light' version when I get going on it.

Let's see, Dome-Blu, huh? Yea, I've been thin'in on it maybe 25% bigger or so. May have to work on it

Maybe I'll try a Bit-Blu, too about 16-20", about 1 ounce

Hmmm... V-tail on a Bit control... Been thinking Bit-SimpleWing to figure out elevons, but....
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