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Old Oct 09, 2001, 07:17 AM
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miserlou's Avatar
Raleigh, NC , USA
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What's the biggest ARF or Kit?

What's the biggest ARF kit or built up kit that you know of that's
a decent aerobatic flyer? Preferably low or mid wing.

Rod A.

P.S. I meant to add for electric. thanks.
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Old Oct 09, 2001, 08:18 AM
Visitor from Reality
United States, VA, Arlington
Joined Dec 1996
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Tom Hunt is flying a SIG BARF CAP - something over six feet span, Dave Grife has a Hangar 9 Edge 540 around the same size. These are about as good for aerobatic capability as you could expect.

IIRC, Tom is using 36 cells on a big Aveox brushless, while Dave's has a geared Astro 60 or 90 on 40 cells.

Big enough?
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Old Oct 09, 2001, 08:40 AM
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Ralph A. D'Amelio's Avatar
United States, MA, Chelmsford
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Kysoho 90 size G-Trick ard ic fully aerobatic 6'ws runs with a Maclim gb/averox and 24/3000 mnih cells. Awesome, flies 10-12 minutes with lots of aerobatics and good throttle management.
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Old Oct 09, 2001, 09:45 AM
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United Kingdom, Bracknell
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Biggest aerobatic kit?? Surely one of the TOC models designed typically for 100-200cc petrol engines ... for example:

http://www.fiberclassics.com/extra_se.html

http://www.fiberclassics.com/giles_se.html

http://www.desertaircraft.com/toc00/pilots.html


Good luck & make sure you post the details of your conversion to electric!
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Old Oct 10, 2001, 09:03 PM
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Quote:
Originally posted by Ralph A. D'Amelio
Kysoho 90 size G-Trick ard ic fully aerobatic 6'ws runs with a Maclim gb/averox and 24/3000 mnih cells. Awesome, flies 10-12 minutes with lots of aerobatics and good throttle management.
Ralph,
can you elaborate a little bit?

What's a Maclim Gearbox? Maxcim?
Which Aveox ? Which ratio?

Andre
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Old Oct 22, 2001, 11:40 PM
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TedLarson's Avatar
Los Altos, CA
Joined Sep 2001
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Quote:
Originally posted by Bill Glover
Biggest aerobatic kit?? Surely one of the TOC models designed typically for 100-200cc petrol engines
Those are some beautiful looking planes.
Definitely good luck! How are you going to get a 35 pound plane off the ground with an electric motor? Maybe 50 cells, and an old furnace-fan motor??

Maybe before I shoot my mouth off laughing at the idea.....Has anyone seen a kit of this size running electric? That would be an amazing site indeed.

- Ted
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Old Oct 23, 2001, 05:39 AM
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Dayton Intl, Ohio, United States
Joined Jan 2000
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Turbo Dantanio had one at the NEAT Fair, 72 cells, with two Astro 60's (I think) coupled together through his own gear drive. Not sure of the size, but it was a lot bigger than the Hangar 9 Edge 540. He had the motor system in the Astro booth at Toledo last year, but it could be two 90s, not sure. It flew well, but he's still doing some prop experimentation. I'm not sure what the total weight was, but the batteries alone are 9 lbs and I would guess the drive system is in the 3-4lb range.

Azarr
www.azarr.com

Quote:
Originally posted by TedLarson


Those are some beautiful looking planes.
Definitely good luck! How are you going to get a 35 pound plane off the ground with an electric motor? Maybe 50 cells, and an old furnace-fan motor??

Maybe before I shoot my mouth off laughing at the idea.....Has anyone seen a kit of this size running electric? That would be an amazing site indeed.

- Ted
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Old Oct 24, 2001, 07:04 AM
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United States, MI, Fenton
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Just for fun, I computed the power output of a DA 150 (the engine used in many of those big 40% aerobatic planes mentioned above) According to the Thrust HP program a 32x12 Menz prop spinning at 6200 rpm (typical for a 150, I think) is 21.4 hp or almost 16,000 watts. Is there anybody who is flying a 16,000 watt electric airplane?

Wiz
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Old Oct 24, 2001, 07:52 AM
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Mike, it really doesn't compute that way. 16000 watts worth of power on a glow isn't the same as 16000 watts of power into an electric. With electric, you can gear up and go to a much much larger (more efficient) fan up front, thereby using less input power for the same output. For an example, an OS32SX (favorite funfly engine due to high power to weight ratio) is rated at 1.15 horsepower at 17Krpms. If you figure 750 watts is a roughly one horsepower that would equate to 862 watts of power. However, to spin it at that rpm to achieve the rated power (which is probably overstated anyway), you have to pipe it and run a 10X4 or so (I used mouse can pipes and 10X4 or 10X5 rev-ups on 30% fuel to approach this rpm). As an experiment, we strapped one of my endo setups on the front of one of David Grantham's competition funfly planes last weekend at a flyin in georgia. After playing a bit with props,.. we had a 14X7 APC "E" on it, at 4.6 gearing, and 10 cell CP1300 pack. Peak watts was a little under 500. The thrust was equivalent to the 32 setup but the weight was of course higher, with 12 ounce battery and 9 ounce motor/gearbox versus the 32 setup at 9 ounces total. Yes, that's really pushing the endo, but I did run one this summer quite a bit at 500 watts in a glider (short runs, like with a competition funfly plane). No, the motor won't last forever, and I wouldn't recommend that setup unless you're gonna run it 30 seconds at a time (like you do in a competition funfly plane),..but the point is,.. we had essentially the same performance at a little under 500 watts that glow was giving at 860 watts (due of course to the much much more efficient prop size). David is one of the TOP NCFFA guys,.. having won their national competition several times, and the last two years in a row, so he's very familiar with the 32's performance. His comment was that the electric definately has possibilities, the power is there, but the weight would have to be worked on a bit. This was a quick experiment, without a high ratio gearbox,. so we really couldn't use the "proper" prop size which I think will be a 15X10 from my previous experiments. Anyway,.. comparing glow to electric based on watts to the prop just isn't the same,.. as seen above, due to the "tiny" props you have to run on glow,.. in that example it took 860 watts worth of "glow power" to get the performance you can get with under 500 watts of e-power. I've flown the comp. funfly planes before, and was competitive in the top few, but not with the very top couple guys,.. and after seeing that last weekend (I flew the plane some too), I really want to try again in the future, but with e-power. Don't need 1300mah due to the very short flights,.. for instance,.. Davids time on the 10 looping touch and goes at the last contest was 13.8 seconds. Too bad there's not a lighter/smaller cell,.. like 400 or 500 mah, that'll take short bursts of 50 amps without losing voltage or melting. Anyway, back to your example, if you took the thrust and pitch speed of a 32X12 at 6200rpms, and then came up with an equivalent e-flight system for the same thrust and pitch speed, I think you'd be WAY below 16000 watts to achieve the same goal. Of course, there are some inherent problems with running a 50" prop and 100 cells in a model
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Old Oct 24, 2001, 08:13 AM
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United States, MI, Fenton
Joined Jan 2000
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Actually, I sort of knew that, but because at that size I have no frame of reference that was the best I could do. I still found the answer interesting.

I wonder if we could set up a ratio using your O.S. .32/Endo comparison and be close. Lets see..... If 860 watts wet power = 500 watts electric then 16,000 wet power = 9302 watts electric.

That's much lower, but it's still an awful big number! And as you said, 50" props and 100 cell packs have their own problems.

When comparing electric power to glow the plusses of electric power are very compelling.....Less mess.....less hassle.....more dependable. But, then the same thing can be said when comparing gasoline engines to glow, so on the truly big ships electric power is less compelling.......at least it is to me.

Still, it's fun to speculate.

Wiz
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Old Oct 24, 2001, 08:16 AM
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Quote:
Originally posted by GWRIGHT
... unless you're gonna run it 30 seconds at a time (like you do in a competition funfly plane ...

Yup, the really 'dedicated' IC funflyers machine off most of the cylinder & head finning for the same reason!
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Old Oct 24, 2001, 08:22 AM
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United States
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Been there, done that,.. don't know if it was really worth the effort to spend all that time just to get 2 ounces off the motor. At the time I was using the Enya 35 heli motor, which had a big head. Removing all the "excess" head, all the fins, and shaving the mounting lugs down, you could get that 9 ounce motor to 7 ounces including mouse can pipe and header. Bolt on a larger bore (8mm throat) carb from one of the larger enyas,..forget which one,..and power was great,.. but when the 32SX came out, it was equal or better, with no mods.


Quote:
Originally posted by Bill Glover



Yup, the really 'dedicated' IC funflyers machine off most of the cylinder & head finning for the same reason!
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Old Oct 24, 2001, 10:16 AM
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I never went as far as chopping bits off the motors (never did fun-fly that seriously). But for my last model (piped Irvine 36) I couldn't decide whether the tail surfaces should be soft sheet with lightening holes or built up from strip wood ... so I made 2 complete sets and weighed them (the sheet ones were lighter)!
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