Some second opinions needed

[1stCavArmyVet]

Ok I figured I would throw this up here, since the guys at my airfield can't seem to make up their minds. My wife and I got ahold of an older Hegi models Snoopey II. About a 10 foot wingspan. From what little I can find on it, it looks like it calls for a 26cc motor. I would like to maybe do an electric conversion or a glow motor on it, but cannot really come up with some solid numbers. So if anyone here has some input, I would really appreciate it. I'll try to get some pictures of it up here later tonight.


Shea G
MMO Radio

 

[rockyboy]

I'm not sure about calculating it directly from a nitro motor size to electric, but if you have a weight for the dry airframe we can figure it out that way like it's a scratch build kit.

 

[Hai-Lee]

The simple rule I was taught for quick electric conversions was to multiply the motor capacity, (in Cu In), by 2000. The resultant number is the number of watts required.

Then look at the original propeller diameter and pitch and find a motor of the correct power rating that develops its max power using a prop of the same specification. (higher or lower Kv rating to suit).

I do question the 26cc though as that equates to 3200 Watts, (almost 4 horspower)!!! I suspect you missed a decimal point and the 2.5cc to 5cc range (or 320 to 640) watts seems a more likely figure.

The normal guide for motor size based on weight is between 100 and 200 watts per pound. Is the plane that heavy? 16 to 32 pounds?

Hope that helps!

 

[1stCavArmyVet]

I got her put together and on the postal scale today (don't ask how LOL). She comes in at just over 9lbs 15oz. Here is a shot of her I just took. I set it next to my EFlite Corsair for a size comparison. The motor is a .60 marine engine I had lying around just to show the oddball engine bay (also pictured). Not sure of exactly what motor was supposed to go on it. I am finding little documentation on her. What I do find is in German. I don't mind going any of the three routes, Gas, Glow, or Electric. Just need to figure out what size in each class I need.

 

[Geeto67]

most 10' wingspan planes use a 1.2-1.5 two stroke. Looking at the dimensions you laid out, the Rascal 110 is probably the closest ARF model in both size, weight, and configuration and they recommend:

2-Stroke 1.2 - 1.5 cu. in. (19.7 - 24.6 cc)
4-Stroke 1.2 - 1.8 cu. in. (19.7 - 29.5 cc)

for electric power for the same airframe they recommend:
Electric Power: 1600 watt (6320 - 250kv) Brushless Motor; 80A ESC; Lipo Battery Pack
and to be honest, I actually think 1600 watt might be under powered.

Here is a thread on a Rascal 110 conversion where they discuss different electric motors and batt cell configurations:
https://www.rcgroups.com/forums/showthread.php?1603060-My-SIG-Rascal-110-Electric-Conversion

Now, if you want my advice - at 10' wingspan you are better off sticking with gas. Why? well even if you go electric you aren't park flying that big of an airplane, so you'll need an AMA field and AMA insurance. And as long as you are going to need that, might as well get the most amount of flight time you can.

 

[1stCavArmyVet]

Thanks for the info Geeto. I'm actually both an AMA member and a member of a club down here in SW Florida. I own a few park flyers but most of my aircraft are bigger. I have an older 88 Komet twin engine I am doing an electric conversion on one day when I have time.