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Old Jan 27, 2003, 08:37 PM
Registered User
United States, FL, West Palm Beach
Joined Jun 2001
2,216 Posts
Motor for competition fun fly

Hello All

I was wondering, what motor would be the lightest(no more than 15 oz) motor/controller/pack setup to spin a 9x6 or 10x4(preferably this one) prop 18,000 RPM(has to be maintained). The total flight time will only be a max of 1 min long.

Here are the specs of the Plane.

http://www.diamonddustrc.com/DiamondU.htm

I would like to use lithium batteries(Kokams), but what battery configuration and cell type would be ideal.

Thanks
Carlo
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Old Jan 28, 2003, 04:09 AM
WATTSUP.SE
Jocke's Avatar
Sweden
Joined Dec 2001
2,307 Posts
sheck aout the new Plettenberg Freastyle motors
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Old Jan 28, 2003, 06:47 AM
310mph Kolibri T25 Swist
henke's Avatar
Sverige, Kronobergs Län, Ljungby
Joined Jan 2001
4,821 Posts
Hi

A .32 os is 1.2hp =880watts

an electric motor to perform like that would need 600-700watts in.

1min flights.... 8xZapped RC1600 at 85A wil run for 1min and give almost 700watts....


but it´s impossible to spinn a 10x4 to 18000 on 8 cells!

rather use a B40 7L 4,4:1 15x13 got more thust and higher pitchspeed, at 55A 71mph and 96oz thrust....

or maybe the HP Ergo.... have no numbers on that one though...


...maybe your loops will be bigger with a bigger prop....gryo effect...

/Henke
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Old Jan 28, 2003, 07:46 AM
Product Manager at Hobbico
GWRIGHT's Avatar
United States
Joined May 2000
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the gyroscopic affects become too large with the really big props. I have a diamond unlimited I'm finishing to play with motors for the same purpose. I did a bit of research last year with another "stick" plane (competition funfly plane). The diamond unlimited is not a very good plane for those events (I used to fly quite a bit of competition funfly, and I'm very familiar with the airframes, the diamond being about the worst of the lot). I just happened to have this kit here, and figured it would be a good testbed for power systems. I've played with a B50 13S on a test stand with various props/gearing, but I plan on ordering a B40, low-turn "short" motor (roughly 4 oz motor/gearbox), with "tweaked" motocalc numbers (closer to reality),.. and comparing everything on the planet, it appears a 7-cell zapped CP1700 (RC1600SCR really) pack, with the B40 5S and a 12X6 APC "E" prop will be the best place to start. That should be about 100 amps, which those cells will take in short bursts, the wieght will be comparable to a funfly motor setup, and thrust/pitch speed will be very close, I'm jsut hoping the 12 inch prop at lower rpms is not too much gyroscopic force. The events only require 10 to 15 seconds of power,..the JLS combo is the longest one, but in the 25 to 30 second range and you aren't at full throttle the entire time, but using the throttle a LOT even in that event, so duration is of no concern, just bags of power in short bursts. If I have to go smaller on the prop, the 11X5.5 would be the next step, overall efficiency drops a lot just giving up one inch of prop, so even the 4S might not be quite enough, and I might have to go to another cell or two. This has been int he back of my mind for a long time, and I hope I get the time to persue it this year. I think e-power could actually have an advantage due to the lower motor weight (shorter moment of inertia in pitch since the bulk of the weight is battery and that would be closer to CG),.. and much better throttle response.
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Old Jan 28, 2003, 11:06 AM
I hole jumped him!!!
Lance's Avatar
Amarillo Intl, Texas, United States
Joined Dec 2001
931 Posts
Quote:
Originally posted by GWRIGHT
.......I did a bit of research last year with another "stick" plane (competition funfly plane). The diamond unlimited is not a very good plane for those events (I used to fly quite a bit of competition funfly, and I'm very familiar with the airframes, the diamond being about the worst of the lot).
........I think e-power could actually have an advantage due to the lower motor weight (shorter moment of inertia in pitch since the bulk of the weight is battery and that would be closer to CG),.. and much better throttle response.


Gary, out of curiousity, which Fun Fly plane would you recommend? Just asking for your opinion, not wanting anyone to try and start a debate here.

With fun fly season just about to get started around here (the weather around here is already looking nice) I am thinking a month or so ahead to my next fun plane. I'm not sure my Hobby Lobby Three Dee would hold up with a geared B40/6L and 7 CP1700's anyway.

Lance
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Old Jan 28, 2003, 11:18 AM
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United States, FL, West Palm Beach
Joined Jun 2001
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Hello All

Thanks for your imputs.

Gary,

I was just wondering about what you said, "diamond unlimited is not a very good plane for those events. " Do you meant that it isnt good for unlimited events, and if so what makes it the worst of the bunch. Im not trying to start a flame, Im just curious and I look forward to your response.

Definitally keep us posted on your progress.

Carlo
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Old Jan 28, 2003, 11:42 AM
Product Manager at Hobbico
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United States
Joined May 2000
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the diamond unlimited flies well, if flown FAST(compared to most stick planes), due to the airfoil, but it has some quirks, like when you slow it down, it flies, flies, stops flying, no warning at all. It doesn't pitch nearly as well as a "true airfoil" plane either, so looping maneuvers require a LOT more power to do properly with it. Good ones currently are the minus (can be built stick-style for unlimited class, or with a profile fuse for funfly class), the Menace, the smith special, and just about anything you want to throw together with the vess airfoil (many people just use that airfoil and tailor the numbers ,..i.e. span/chord/tail length to suit their personal preferences). I'm not sure, but I think Jerry smith's planes use that airfoil now too. I have my own preferences, so If I get as far as figuring out the power system and practicing for the event this year, I'll just do my own plane instead of someone else's kit.
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Old Jan 28, 2003, 12:05 PM
I hole jumped him!!!
Lance's Avatar
Amarillo Intl, Texas, United States
Joined Dec 2001
931 Posts
Quote:
Originally posted by GWRIGHT
I have my own preferences, so If I get as far as figuring out the power system and practicing for the event this year, I'll just do my own plane instead of someone else's kit.
Well it's been said before, but bears repeating....If you kit it, they will come.

I know you're a busy man and all.....but

....can I pre-order?
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Old Jan 28, 2003, 02:06 PM
Product Manager at Hobbico
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United States
Joined May 2000
5,156 Posts
hehe,.. haven't even got sport-e-sticks shipping yet,.. although it should be this week. I actually have a full-time job too ya know, and it takes lots of my time,..plus I have to go hit a little white ball with sticks occassionally ,.. although most of them go into trees or water, it's still fun
I don't know if there would really be a market for an NCFFA type plane specifically designed for electric. Might not be worth the effort.
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Old Jan 28, 2003, 02:20 PM
Old age is not for sissies
Azarr's Avatar
Dayton Intl, Ohio, United States
Joined Jan 2000
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It's good to see some excitement about competition fun fly. Looks like we have the same thread going in three different places.


Don't forget the E Cubed R/C Challenge - I'm offering cash prizes to the highest placing "E" powered planes in Sportsman and Masters Unlimited and $500 for winning the Masters Unlimited. Not quite TOC stuff, but should help with travel expenses.

There's more info on the NCFFA Site at:

http://www.ncffafunfly.org/

It would be great to see a bunch of E planes flying this event.

Azarr
www.ecubedrc.com
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