Balsa USA Bristol M1 conversion to electric - how to?
 

I have a very nice Balsa USA Bristol M1 that was flown with a 46fx glow engine. For the past 8-9 years its been hanging in my hangar and now I want to fly it again with an electric motor. This will be my first electric airplane and I need some advice regarding which motor I should consider along with the ESC and the battery packs to consider. All the servos in this plane are std futaba 148 servos and I reckon the plane with engine weighs not more than 6 lbs.

thanks in advance.

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

I'm enclosing a few shots of my M1a conversion. Power initially was an Aveox 336/38/3 with a 4:1 MaxCim gearbox pushing an APCe 15/8 prop with 12 A123s. Presently it is flying with the Aveox DD on 5 LiPos and a 13/8 prop. both set-ups provided plenty of power, but the DD set-up gives just a bit more "snap." ESC is a Sivler Series 60 from Great Planes with a Kool Power UBEC. The motor mount is a .40 size glow aluminum mount with a hose clamp. I did reinforce the flimsy stock firewall. Weight and balance are not an issue becaue of all the room in the fuse. If I can help more let me know.
Walt

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

thanks for the info.  How about this one:

Motor1: AXI 4130/16 (http://www.hobby-lobby.com/brushless_axi4130.htm)
Battery: 5000mah 6S
ESC: SPIN 77 Amp Opto Brushless Speed
Prop: 15 x 8
(Can it take such a big prop?)

cheers

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

Hello,

The 4130 will work with a 15x8 prop on 6S, although I think it might be overkill. I have been flying a 6 lb aerobatic airplanes on the same motor using a 16x12 prop and a 5S battery. It depends on the weight: up to 7 lbs on 5S should be fine for "peppy scale flight". If heavier than that, then a 6S battery might be a better choice.

Good luck,

Teo

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

right, let me figure this out.  I want genuine scale power. not steroids. 

The other option would be : AXI Gold 2862/12 outrunner for a 13x8 to 11x6E prop.  For airplanes upto 106oz.

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

I'm not really up on Axi's (had a bad one early on), but I believe either motor would work well. remember these old rotary engined birds had very large props, so a lower pitch larger diameter prop is best. I think that when I had the geared set-up on my Bristol I had an 18/6 prop on it. Plenty of ground clearance. I plan to try a 14/6 this season as the 13/8 gives very un-scale flight speeds!
Walt

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

On a plane such as this, even having modest power (say about 400 watts) will work well provided that it goes into a large enough propellor. Having said that, this plane would probably be happier with 400 watts going into a 14x10 prop than a 13x8. I am just using these props for example purposes. I think that the AXI 2826/12 will work, but I think that you will be limited to a 13x8 prop or so if running it on 4S. You can always run a motor at a lower voltage than recommended, so a 4120/14 would probably work on 3S or a 4120/18 on 4S. Either way, you would be able to spin a 14 or 15 inch prop at 400 watts or more. These WWI planes have short noses, so having a heavy motor may not be much of a hinderance. Either way, even the larger motors are a little lighter than the .46 they replace.

I am currently building a BUSA Eindecker just for the fun of it. The power will be a BRUSHED Astro 15 cobalt running through a 4.69:1 gearbox. I will probably run it on either 4 or 5S and try to spin a 14" prop. This plane is known to be lighter than the Bristol, so I am not too worried about having enough power, even if it is in the 400 watt range.

Good luck,

Teo

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

Hello Ragz


I have built and maidenend the BUSA Bristol M1 last year. It is powered witha Turnigy Aerodrive SK4260-500 on 5/5000mAh lipo batterys. Together with a wooden 15x6 propeller, the motor draws 41A and it flies the bird fantastic at about 1/2 throttle. There is no use in an overly powerful setup, as the plane seems to have an inherent max speed. Going full throttle wont make it faster, it just gives the plane a little more "umph" for aerobatics. For scale appearances I would say that a 15" prop is the minimum, a 16-17" would be ideal.

Greetings Robin

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

Robin,
I agree on that "inherent max speed" on the M1a.

Now WHERE did you get that MAGNIFICENT FLYING SPINNER?????????
Walt

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

Hi Walt

Yep, the M1 is for sure no racer. Altough I think that the spinner has also some effect on the speed of the plane. There is a distinct sound to hear when the plane has reached a certain speed. Kind of turbine effect I think.

And the spinner is selfmade, as, as you have experienced surely too, there is no spinner commercially available. The base plate is made from 1/8" aluminium, and the bowl is made from glass fiber. The GF bowl was formed into one of those hollow styro half-spheres that you find in the crafts section of hobby stores.

The whole assembly was a real "PITA" to balance, but worth every invested hour.

Greetings Robin

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

Nice work, thanks
Walt

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

Actually BUSA and Arizona Aerocrafters offer an M1a spinner - for upwards of $75.00!
Walt

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

Hi Walt

Yeah, I have checked those spinners, and also the one from Gene Barton which is cheaper (~50$) than the Arizona models one. But those spinners are all the wrong shape, as they are intended for Albatross fighters.

And I admit, that I have some problems to spend more money on the spinner than on the kit itself.......but I am known to be cheap....;-)

Greetings Robin

RE: Balsa USA Bristol M1 conversion to electric - how to?
 

moi aussie!
Walt