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25 size mustang - how do i convert this?

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Old 09-16-2004, 08:49 PM
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rc34074
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Default 25 size mustang - how do i convert this?

please give me your advice on how to convert this plane to electric- its a modeltech arc mustang. its all wood with the following specs on the box: 50 inch wingspan, 428 sq inches, 37 inch overall length, 3 lb flying weight, the box says to use a .25 to .28 2 stroke engine.

right now my everyday plane is a hangar 9 mustang with a super tiger g90 2 stroke engine, which i fly full at full throttle from takeoff until i start my landing approach. so ideally i would like to have somewhat similar performance- 75-80 mph strafing runs , 8-10 minute flights at full power, rog takeoffs. flights every 1/2 hour or so.

i expect to use a brushless motor but i have no idea which motor, esc, batteries, etc would give me performance anywhere near this level.

what would you suggest i use? where would i buy it?

thanks

ed
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Old 09-17-2004, 09:55 AM
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StephenT
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Default RE: 25 size mustang - how do i convert this?

Your Mustang sounds the same size and weight as my Modeltech Extra 300. It uses this set up.

Jeti 30-3 direct drive
9x7.5 prop or 10x6
12 1800 mah Hecells or
11.1 Volt 20C Kokam 2100 Mah
40 Amp Jeti controller

7 minutes flying time.


Where can I get a Mustang like yours.
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Old 09-17-2004, 11:49 AM
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Matt Kirsch
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Default RE: 25 size mustang - how do i convert this?

I highly suspect that your 70-80MPH estimate is closer to 50-60MPH, unless of course you've had it clocked by the cops The smaller plane will look like a streak of lightning at 60MPH.

Anyway, for full-flight, full-throttle operation, you really need to pay attention to cooling, and perhaps "overbuild" the power system a bit. That is, put a power system in that's not running at its maximum capacity at full throttle. You may want to use a motor, ESC and battery that can handle 50 Amps, but only run 40 Amps through them, for example. Otherwise, you'll have overheating problems.

Also be aware that the minimum cycle time for LiPolys is 1 hour. That doesn't include cool-down time, and assumes you don't completely drain the batteries each flight.

For a 3lb plane you'll probably want 400 Watts for hotrod strafing run performance. 10 cells, or a 3S LiPoly, at 40 Amps will do it. Just a shoot-from-the-hip guess here, but an AXI 2820/12 with a "square" prop like a 9x9 should do what you want, but 40 Amps all the time will be really hard on it. This might be a job for a geared conventional brushless like a Hacker or Kontronik, which I have zero experience with.
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Old 09-17-2004, 11:50 AM
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Default RE: 25 size mustang - how do i convert this?

thanks for your reply- can you give me some idea of the full throttle rpm for the props you list? is the 7 minutes at full throttle? or 1/2 throttle? how much does your extra weigh?

where did you buy your setup? what charger do you have?

this mustang is no longer made, as far as i know. it is a modeltech arc from several years ago. i was going to put a small super tiger in it but decided to look into electric.

ed
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Old 09-17-2004, 09:39 PM
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Default RE: 25 size mustang - how do i convert this?

matt- thanks for your reply. perhaps i should contact some of the motor suppliers? maybe astroflight? hacker? axi? kontronik? hmmm.. who would you suggest i contact?

i thought i would need to add cooling passages through the plane to keep the motor and batteries cool.

thanks for your help

ed
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Old 09-18-2004, 03:48 AM
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Default RE: 25 size mustang - how do i convert this?

Ed,

you gain kind of nothing to contact the motor manufacturers... the knowlage is found here they only make motors, we use them.

I like the high performance geard setups, as I can use a lighter motor and still have massive power. I think a Hacker B50 geard to swing a "large" prop, say 15x10-12 would do best in your little P51. check aircraft-world.com for prices.
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Old 09-18-2004, 06:57 AM
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Default RE: 25 size mustang - how do i convert this?

henke- what rpm would the hacker b50 turn that 15x 10-12 prop? what speed control would you use, with what batteries?

ed
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Old 09-19-2004, 04:08 PM
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Default RE: 25 size mustang - how do i convert this?

ed


Set up is from Hobby Lobby. Batteries are Hecells from edogfight.com. 7 minutes of mixed flying. 300 watts at WOT. Lipo's give it 15 minutes but costs $160.00 compared to $35.00 for 7 min.
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Old 09-19-2004, 09:31 PM
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Default RE: 25 size mustang - how do i convert this?

Henke, you're talking about a prop that's nearly 1/2 the plane's wingspan. That's going to cause some serious torque issues, isn't it?
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Old 09-20-2004, 06:10 AM
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Default RE: 25 size mustang - how do i convert this?

stephent - modeltech does have a .25 size me109 arf that is about the size of this mustang.

a question to anyone - would the hacker b40 be a good choice for this plane? one of the pilots at our field has a small (40-44 inch) wingspan sailplane with this motor, a folding raupner prop, and nicads for power. this plane performs pretty well - it climbs out at 45 degrees!! but it has a real high current draw- maybe 80 amps or so - at full power takeoff. would a b40 turn a prop in the 12-14 inch range with an 8 pitch at maybe 10,000 rpm? or would the geared version, or even an outrunner type motor, be better- maybe with a high pitch (12?) prop -

i am going to check the ground clearance for this plane -

ed
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Old 09-20-2004, 09:59 AM
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Default RE: 25 size mustang - how do i convert this?

Don't get hung up on turning a specific prop at a specific RPM. The thrust here, pardon the pun, is to turn as large a prop as possible at as low an RPM as possible.

I would think that on a 3 pound airplane, even a fast high-performance ship you wouldn't need what I perceive to be some pretty heavy-duty Hacker motors. 300-400 Watts ought to be well within the range of a B40, yes?
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