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Old Dec 06, 2005, 06:45 AM
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Southern Itally
Joined Feb 2004
168 Posts
Electric Combat me163B vs glow HElp needed

Hello, I am seeking help in motor and battery combination for a flying wing ME163-b to be used in combat against glow scale fighters.
This is what I need, we can use a 13 inch max combined (diameter + pitch) prop. That means I could use a 8x5, or 9x4 or smaller props as long as diameter plus pitch is less or equal to 13.
Total rpm on the ground should be around 18k and the heat lasts like 7 minutes.
I will need an inrunner or outrunner that can turn a 8x5 or even an 8x4 prop around 18k on a 3s 3200 mah pack and do it for at least 6.5 minutes , so no more than 30 amps. IS this possible at all? IF so, what motor and prop combo can achieve this?
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Old Dec 06, 2005, 07:13 AM
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Indio, CA.
Joined Sep 2005
511 Posts
Look at the Just Go Fly 400DF, geared 3.89 to 1, you can run the 8x5 or the 9x4 prop.

You can also go with the E-flite park 400 4200Kv inrunner motor, geared at 4:43 to 1, I run both of these set-ups on 1320 to 1500 Mah batteries. I get flight times in excess of 15 minutes at amperages around 20 at WOT.

You didn't give any info about the scale of your plane. IE; wingspan, weight of plane, and wing loading.

I use the above mentioned set-ups on planes up to 2 pounds. AUW
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Old Dec 06, 2005, 07:45 AM
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Southern Itally
Joined Feb 2004
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Quote:
Originally Posted by mlh1961
Look at the Just Go Fly 400DF, geared 3.89 to 1, you can run the 8x5 or the 9x4 prop.

You can also go with the E-flite park 400 4200Kv inrunner motor, geared at 4:43 to 1, I run both of these set-ups on 1320 to 1500 Mah batteries. I get flight times in excess of 15 minutes at amperages around 20 at WOT.

You didn't give any info about the scale of your plane. IE; wingspan, weight of plane, and wing loading.

I use the above mentioned set-ups on planes up to 2 pounds. AUW
Well, maybe I did not explain too well, these planes have to fly in excess of 100 mph, the weight of the plane is probably around 20 oz. wingspan around 32 ".
I am specifically looking for a 8x5 at 18 THOUSANDS RPM, not at a geared 400 that gives me 6000 rpm.
I need 7 minutes full throttle flying time, and no more.
The amps need to be around 30ish.
Thanks.
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Old Dec 06, 2005, 07:58 AM
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Indio, CA.
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ok, I have been having great success with the just go fly 400DF direct drive with a 6x4 prop on 2100 li-pos. I get about 6 minutes out of a flat foam pusher and speeds of 75mph, and 34 amps static.

you can always contact vinnie at Justgofly.com. He is very knowledgeable and extremely friendly. I take it you are flying a wing. Vinnie has many very good combinations for flying wings. Give him a try and see what he says.

Good luck & happy flying
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Old Dec 06, 2005, 08:01 AM
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You need to talk to Vinnie at Justgofly.com. His 450th pushers are very powerful, can easily top 100 mph on about 30 amps. You wont be using a large propeller, (you would likely use a 4.75 x 5.5. Call vinnie he is a great guy and the motors are great too. This motor class is the perfect size and weight for your type of plane.

Alternatively, if you want a bigger inrunner, maybe one of the mega 22/xx/xx series would suit you. They are huge heavy (compared to sp400) inrunners that can swing bigger props. The Mega 20/30/3 might work at around 15000+(?) rpm at around 28-29 amps with the 8x5. Its around 14000 rpm and 33 amps on an 8x6 on 3 cell voltage. I thinkyou are better off with the justgofly.com motors just based on weight savings alone.

Good luck. N_G
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Old Dec 06, 2005, 04:55 PM
Rochester, NY
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United States, NY, Monroe
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Hi Guys - thanks for the kind words, and the referal. Much appreciated !

Quote:
Originally Posted by Italian Flyer
Well, maybe I did not explain too well, these planes have to fly in excess of 100 mph, the weight of the plane is probably around 20 oz. wingspan around 32 ".
I am specifically looking for a 8x5 at 18 THOUSANDS RPM, not at a geared 400 that gives me 6000 rpm.
I need 7 minutes full throttle flying time, and no more.
The amps need to be around 30ish.
Thanks.
Italian Flyer - what you are looking for is a 500 Class approximately 2000 Kv motor. The 18,000 RPM would provide only 85 mph, not over 100, although at that speed, I'm sure it would feel like 100. By going with the 8 inch prop you are looking for over 30 oz's of thrust and under 30 amps will be difficult to find. It may exist, but from the information below I think you'll see that you'd have to go 4S on a 450T to get it. I haven't posted the 450T charts yet - but have them ready to go. The 450T is the 450TH with the MID SPEED bell, which gives close to a 2:1 gearing. We'll discuss three motors (450TH, 450T, 450FT).

The 450FT (2250 Kv) on a 6x5.5 would get you close but you'd lose out on the 30+ oz's of thrust. With this setup at 10 Volts you'd see 90 mph, 17300 RPM, 25.2 oz's of thrust at 32 amps 320 Watts. The 6x4 would unload the prop more and decrease speed to 73mph, but provide 27 oz's thrust at 24.3 amps (243 Watts).

The 450TH would get you the speed you want in excess of 100 mph, but not the thrust a 5x5 at 10 volts would get over 100 mph static, almost 17 oz's of thrust at 289 Watts. BUT a nice thing about this motor is you change the bell and effectively reduce the speed from 3000 Kv to 1700 Kv and can increase prop sizes. I love going out to maiden with a 7x5 prop and then change bells to high speed with a 5x5 prop once everything is dialed in. I'm testing 7x6,7x7,7x8,7x9,7x10 but I think 7x7 might max on this motor.

Check out the charts on http://www.JustGoFly.com - I don't think we have a perfect match for you. A 4S setup might get you there on a 7x5 prop though.

Have fun and report back if you find what you're looking for.

MLH - 34 Amps on the 400DF ? Time to boost you into the next class of 450TH. I know the 400DF can handle high amps for short bursts, but beeee careful. More than 45 seconds at the Wattage will leave a smoke trail. The 450TH can handle 300 Watts all day long and 350 Watts burst for 30 seconds. But touch 400 Watts and you're over the top.

We're working on 500 size and some motors that really have me excited. More when I have real data to post. Right now I'm flying them and getting a "feel" for them - weather permitting.

Nutty Gnome - why aren't you out flying ? I rebuilt my heavy Wing/Jet and am loving the control I get with the 450T in it and high thrust. It's not a bullet but it is so draggy it's not designed to be a bullet. I think it puts on air brakes around 70mph. I reshaped the nose and got about 8-10mph increase in speed, but still it is very draggy. I'm working on a very thin wing for the high speed stuff.

Vinnie
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Old Dec 07, 2005, 07:36 AM
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Southern Itally
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Thanks JustGoFly. This sounds pretty good, What I am looking for is hard to find.
The ACES combat is all glow powered, They only allow the electrics to have 16k on the ground. This is a big problem because the gas guys are unloading to 20 in the air, so to be competitive I will have to adjust travel on the ground and then once airborn, hit the power switch. they check rpm on the ground and they need to have full access to the radio while you do that, but for them to figure out that I got the dual rates setup on a side knob on my 9cap would be a bit hard to guess. I want to compete on level ground but electrics don't unload in the air like the .25 engines do.
That's why I am specifically looking for some 18krpm. THe 8x5 prop is because the plane will weigh probably a bit less than 2 lbs, and because 13 is the max number allowed diameter plus pitch. These have to be 1/12th scale wwII fighters, and with a 30ft streamer to carry in long vertical manouvres, I don't want to have a target drone, I do need better than 1:1 in the air so I need 32 oz thrust, not static thrust but in flight thrust, plus I can live with a 90 mph speed. Gassers top 130mph in this class of combat here in Europe.
Ohh I forgot, there is no limitation in type and model of motor and no limitation on batteries and currend draw. I guess I could go 4s after all, but I need 7 minutes of full throttle flying.
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Old Dec 07, 2005, 07:50 AM
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Southern Itally
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wRong , it seems I was wrong about my total weight. I calculate weight around 900 grams if using a Hacker B50 which weighs 340 grams alone. I can use less thrust if the 450ft weighs less.

450FT might do it

6 diameter
5.5 pitch
APC
10.0 volts at esc.
714 grams of thrust
25.2
17300 rpm
32 Amps
320 watts
2.2
90.1 mph
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Last edited by Italian Flyer; Dec 07, 2005 at 07:58 AM.
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Old Dec 07, 2005, 08:51 AM
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Nutty Gnome - why aren't you out flying ?

No kidding! I'm still sidelined by the ESC. I'll finish construction on the wing this weekend though, so maybe mid next week I'll get to fly the 1700kv. I'm dying to see your amp draws and rpms, please do post them!

N_G
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Old Dec 08, 2005, 07:02 AM
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Southern Itally
Joined Feb 2004
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Only one question... can the 450TH be used with some kind of fan unit?
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