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Foamies and powerplants

Old 04-20-2010, 10:51 AM
  #1  
Nesal
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Default Foamies and powerplants

Hi guys,
Im new to electric flight and this forum but not rc planes... I looking to get something electric and smaller than my current nitro plane and saw some foamies down at my lhs which looked nice. They have a mig which is very cool and definitely caught my eye the problem is being new to this I have no idea of what to put in it regarding BL motor and esc, I know the esc depends on the amount of amps the motor draws, but what motor! Another thing is I have 3S 1800mah lipos but that seems way overkill for a little foamy isnt it? How do I select an adequate BL motor for my electric plane? I will be ordering it off Hobbyking and have a spare 30A esc off of a helicopter, could I use that? in theory yes, right?
Thanks guys, great forum!!
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Old 04-20-2010, 02:18 PM
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capn chaos
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Nesal,
Welcome to Watt Flyer and electric flight in general. The combination you will need varies greatly but will depend on exactly which foamie you are looking at. Also, it would be helpful to give a bit of information on "watt" type of flying you will be doing, sport, 3D, casual aerobatics for starters. All of this is watts/lb dependent. Ed's (AEAJR) sticky Everything You Wanted To Know About Electric Powered Flight will be "mandatory" reading material.
Give us a bit more info and you will have plenty of helpful suggestions from the "gurus" here.
Good luck and again WELCOME>
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Old 04-20-2010, 11:52 PM
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Nesal
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Thanks for the heads up! Will definitely give that a read. Im actually considering various options at this point but basically am worried about my piloting skills and which plane to choose. I have been out of the hobby for a while, I used to fly about 8 years ago and learnt on a .46 glow trainer, I got back into flying a couple of months ago and flew the trainer as well as a lot of sim, the trainer crashed due to an inflight failure (wings came apart) and Im now flying a .46 Spacewalker (have only flown it twice) but I seem to be flying fine and can do basic aerobatics and so on... So I really like the idea of an electric plane, there is a flying field pretty near my house where only electrics are allowed and I would like to get something fun for there. I have considered something like an Eflite BL P-51 which is pretty appealing to me but what I really would like is a EDF jet, which seem to be pretty decently priced, my only worry is how my piloting skills will hold up to a fast edf jet... other options include a foam mig which I saw at my lhs which also seems like a fun plane but it is small, probably weighing a pound or so...
Decisions decisions...
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Old 04-21-2010, 12:12 AM
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capn chaos
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Nesal,
Can't even begin to hit on the parallels. Flew 12 years ago, learned on a 40 size Sig Kadet (many years before). EDF's got me interested in electric flight. Flying field close accepts electrics, IC not so much.
A suggestion: getting into electrics, work with what you are used to. Tractor props (pushers are OK too) sport planes, warbirds if you will, just to feel your way into electric flight best described as a "juggling act". Balancing power requirements, ESC, batteries, flying styles will all fall in place much faster with planes you have backgrounds in. Glad your'e back in the air. There will be plenty of support here on WF when you have questions.
Ed's (AEAJR) article is great. First rule is watts per lb of plane. Depending on a few variables, to sustain flight requires 50-75 watts per lb. For mild areobatics 100 watts per lb. Will let you read the rest as it is invaluable.
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Old 04-21-2010, 12:17 AM
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mesh
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The two simplest (most improtant) stats a motor has is weight and KV-rating.

For a given model, finding the right weight motor should be easy. Look at what size motors people put in similar planes. A larger motor will of course be able to handle more power. 25 grams is normal for a "shockflyer" which hangs by its prop a lot and does fancy tricks, and a 50-70 gram motor is usual for models around 500-800 gram.

The KV-rating is basically the "virtual gearing" of the motor. A given motor can be made in several different KV versions, depending on the type of winding and the number of turns/thickness of wire. A 20 gram 1200KV motor might be most efficient when it spins a 9-inch propeller (this is a common set-up for a 3d shockflyer), while the same motor in a 2500KV version would need a 5 or 6 inch prop. Flying wings and other pusher-planes often use smaller propellers, so high KV motors.

So if you know the weight and prop size you want to run, you can tell pretty well if a given motor will suit you.

I see now that you specifically mentioned EDF jets. The EDFs are basically a tiny propeller, so suitable motors will have very high KV-rating, around 4000. These are often brushless inrunners instead of outrunners, but the same basics apply. An additional problem is that the motor has to fit well inside the fan cowling/housing, and I don't know very much about EDFs.

I would look at what kind of EDFs hobbyking sells, and also at the comments on the high-KV inrunner motors meant for EDFs, people often post their setups there, and you can figure out what will work together.

You should be able to use your heli 30A esc, although for a 20-gram motor it would be overkill. Heli escs also tend to have weird "governor" modes, and soft starts, if it is programmable you should be able to turn that off.
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Old 04-23-2010, 12:50 PM
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Nesal
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I took a picture of the little mig 29 parkflyers box:


What motor would you reccomend? Thanks!

It says 1000mah lipos.. I have 3s 1800mah and would like to use them will I have a problem with the center of gravity? How do you adjust it so its flyable? Sorry for the stupid questions lol!
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Old 04-23-2010, 04:48 PM
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Nesal
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Saw this, but people are saying about 150grams of thrust... I would need 340 since thats what the model weighs right?
http://hobbyking.com/hobbyking/store...idProduct=5377

So far this one seems more aproppriate
http://hobbyking.com/hobbyking/store...unner_(Eq:2204)

Another option:
http://hobbyking.com/hobbyking/store...less_Outrunner

http://www.hobbyking.com/hobbyking/s...idProduct=5112


Thoughts? Thanks!

Last edited by Nesal; 04-24-2010 at 01:48 AM.
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