|Mar 30, 2012, 05:31 AM|
Joined Mar 2012
Nitro to Electric conversion of 20 year old foam drone
I have a couple of the old Mig 21 foam drones. They run on the RS .61 nitro engines. I have baught the last gallon of nitro and glowplug, and tired of cleaning up the mess & dragging around the tools needed to start. I am going to change it over to Electric but new to this portion of the sport.
Just weight it at 8 lbs fully loaded with battery, fuel, & engin. Measures 5'4" long and 5'6" wingspan. Not sure of the mass of the wing as it is a close respresentation of the Mig and contoured wings. It was designed to fly slow and close to anit-aircraft guns and shoot at as if it were far away.
The last bit of this equation and what really has me stumped is that I have a couple hundred 12-5 wooden props. I would like to convert to electric and retain this prop just because props are not cheap when you crash like I do.
So this is my question. DOES ANYONE KNOW WHAT MOTOR, ESC, BATTERY WHOULD BE BEST? I cant understand the watts versus lbs theory. I am just too new to this subject and dont want to reinvent the wheel when someone already has.
8lbs solid foam Mig21
5'4 long x 5'6"wing
12-5 wooden prop
and would like to fly it a little faster than drone speed.
|Mar 30, 2012, 05:58 PM|
Sverige, Värmlands Län, Filipstad
Joined Jan 2009
How large prop diameter do You think the plane can use to still get reasonable good prop clearance to the ground? I assume the glow engine that is in the plane today is mounted in the nose.
Do You have any photos of the plane to post, on the nose and engine also.
Maybe something like this brushless motor (if you prefer the cheap route) could work rather good:
And a 100 amp electronic speed control (ESC) like this that has battery eleminating circuit (BEC) so you can get power from the LiPo battery to servos and receiver:
You do not need to use BEC but You can save some weight since You do not need an extra smaller reciever/servo battery then.
And 6 cell LiPo battery is probably what You need for such plane, maybe 4000 - 5000 mAh, 45C:
More mAh will be heavier but get more flight time.
You probably want at least two LiPo batteries so You can charge one at the field while flying with the other pack.
You need connectors also for the batteries, ESC and charger.
I would use electric props, APC Thin Electric works fine, try 12x8 and 12x10 if 12 inch prop will work without to close to ground (prop clearance). Maybe a 11 x 10 or 10 x 10 prop can work but pitch might be to much (prop stall).
You want to measure current and watt during setup before You take to the skies so You do not exceed motor specifications about max continues amp and max watt it can hadle. Same with ESC, you do not want to burn it because You exceed how many amp it can hadle continously. A watt meter is what You want then (Hobby King seems to have none in stock).
You need a charger for LiPo also, try one that can handle 6-7 cell at least, something like this will work for 6 cell LiPo:
At the field You can use a marine battery 12 volt or similar (not a car start battery) about 80 Ah can be good. At home it is better to use a powersupply like this (for a charger like above):
Above is just suggestions what might work for You based on the info You provided and get Your thoughts in right direction.
Try to study as best You can what may best suit You plane and the performance You expect.
Hobby King was selected just so You see what some cheaper components may cost, other companies and other brands have fine components also. ESC is a vital component in an electric setup so it is probably wise to not buy to cheap.
It is no problem to find electric setup that is equal or outperform a .61 nitro glow engine but You have to do some basic calculations to get resonably good results with your exact plane.
Try to get air to cool the motor, ESC and battery so in nose You should have air enter and go over the motor, ESC and battery and finally exit at some ventilation holes in rear region of fuselage about 3 times area hole for exit compared to inlet.
Going from glow to electric for nitro planes can be tricky to calculate best performance. Prop selection (larger diameter props is what electric motors like) and proper cooling of the components may be a challenge for conversion of glow to electric.
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