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View Full Version : Replacement for a hot .15


elitheiceman
01-31-2007, 12:29 AM
I've been away from the hobby for a number of years, but I got the urge to build again, and with the stuff that's available today, electric seems to be the way to go. I dusted off an old Jack Stafford Super Buccaneer, an early quarter midget kit. The recommended engines are an unmuffled Rossi .15 for racing - that ain't gonna work for any number of reasons - or a K&B 3.5 for sport flying. I'm sure that either set-up is faster than it needs to be for these old thumbs. So I'm looking for suggestions for a combination that will fly it reasonably smartly without costing an arm and a leg. And I'd like to keep the prop to 9" or less. I will be grateful for any suggestions.

Sky Sharkster
01-31-2007, 02:53 AM
Hello elitheiceman, Welcome to Wattflyer! Well, it seems you're willing to dive in with both feet! Normally I'd suggest you try a simpler plane like the GWS E-Starter to get used to the whole electric world of batteries, chargers, etc, but instead I'll just plunge ahead and make few recommendations for the plane you described. Electric conversions aren't usually a direct replacement for a given glow motor, mostly we go by weight, watts, size, type of flying you intend to do.
However, it so happens that one electric motor manufacturer has made life easier by labelling their motors with the equalivent glow size; E-Flite.
These are very good "everyday" motors, not cheap knock-offs, not racing or high-performance motors, either. They're in the middle.
http://www.atlantahobby.com/shopexd.asp?id=6136
This would use a 40 amp to 45 amp speed controller, here's a selection;
http://www.atlantahobby.com/shopdisplayproducts.asp?id=171&cat=36+Amps+%2B+Brushless
And another motor that will work well, The AXI 281412;
http://www.hobby-lobby.com/brushless-axi-combo.htm#281412
Both of these are "Outrunners" and will use a 9-1/2"-11" prop.
Last, The Jeti Phasor 15/4, This is one of the very few "inrunners" that will swing a decent-sized prop without a gearbox.
http://www.hobby-lobby.com/brushless-combo-jeti.htm#JEP154
As you can see, it's looking like $150-$200 for the motor/ESC.
There are cheaper components around, but very few better.
Hope this helps! Any other questions, ask away, there's lots of folks here who are willing to pitch in with advice, even if we don't always agree!
Ron

Matt Kirsch
01-31-2007, 02:38 PM
The prop/battery recommendations for those motors are for general sport flying. You'll need to make a few adjustments if you want speed with this quarter midget racer. The midget's gonna needs some speed to stay aloft with it's stubby little wings :)

First, go with the motor that has the highest Kv rating in the series.
Second, go with the highest-voltage battery that they recommend.
Third go with the highest-pitch, smallest-diameter prop you can get that will not overload the motor.

When you're dealing in high-performance stuff like this, a Whattmeter is invaluable.

Solid Hit
01-31-2007, 03:01 PM
All the above is great information and as Sky Sharkster suggested, if you haven't flown in a long while, you might want to invest in a trainer to shake the cobwebs out from your thumbs. I came back to the hobby after a 30 year absence and needed to do a fast refresher with some trainers to get the feel for the controls and orientation. It comes back quickly.

Dr Kiwi
01-31-2007, 09:35 PM
Electric conversions aren't usually a direct replacement for a given glow motor, mostly we go by weight, watts, size, type of flying you intend to do.
However, it so happens that one electric motor manufacturer has made life easier by labelling their motors with the equalivent glow size; E-Flite.


One of the problems I see in the E-flite system is that the "glow equivalency" must be based on pretty wimpy glow motors. I'll bet a Rossi .15 is at least a match for my MVVS .15 which is rated at 515W @ 26,000rpm. I know from testing that it spins an 8x6 @ 14,000rpm. I really can't imagine an E-flite .25 (rated at 425W max) competing with that. Similarly an E-flite .46 is rated for 800W - I suppose a bog standard O.S. 40 might be about the same, but an MVVS .40 is rated at 920W, and a .46 MVVS is 1200W.

I really think one needs to "go up a size" to get an electric equivalent to a hot motor like a .15 (2.5cc) Rossi or MVVS, or my 3.5cc PAW Diesel.

Sky Sharkster
02-01-2007, 03:26 AM
Hello Dr Kiwi. I agree that the motors I mentioned are not equal to a Rossi or MVVS in power. That's the point.
Elitheiceman stated that these would be "faster than it needs to be for his old thumbs". I didn't recommend a Plettenberg or NeuMotor, not only for the obvious cost factor, but because he made it clear he wasn't looking to duplicate the original power. Quite the opposite.
I also made it VERY clear the E-Flight was not a racing motor, it was an "Everyday" motor.
I was not comparing the recommended motors to a racing motor, I answered the question as it was asked.
Ron

flypaper 2
02-01-2007, 01:10 PM
Eli:
What's the wingspan, wing area, and weight of this plane.
Gord

elitheiceman
02-01-2007, 05:53 PM
Gentlemen:
Thanks for your suggestions. To clarify a bit, my intention is sport flying, and this won't be the first plane I fly. I have a couple in the attic I might be able to resurrect, and plans on the bench for a .20 size 4 ch. that is pretty close in size and specification to the B-3, but looks like it might build up a bit lighter.

Spec's. for the B-3 (Super Buccaneer): wing span - 43", area - 305 in², weight - 2½ - 3 lbs.

Thanks again.

flypaper 2
02-01-2007, 06:12 PM
Eli:
suggestion. going from glow to electric, the planes can be lightened up quite a bit as you don't have to put up with the vibrations and need for fuelproofing,etc. for instance 1/4 ply firewall can be replaced with one half that thickness. Liteply can be replaced with hard balsa, etc. Should be able to drop her down to 1 1/2 to 2 lbs. Motor mount, landing gear mount and wing mount, strong, the rest as light as you can get it. Lighter flies better :p Hope this helps.