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Firebat build

Old 04-10-2007, 09:56 PM
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Default Firebat build

I have an old GP Firebat deluxe I am building. I would like to use one of the brushless motors I have. They are both pretty much identical and size wise should be a good fit right into place of the stock 400 speed brushed pusher which uses a 125 by 110 mm prop. The main difference between the 2 brushless motors I have is that one is 1200 kv and the other 980 kv. Both are max current 30 amp (and I have a 30 amp brushless controller to use), max efficiency 98%. Which of these motors would be better for the Firebat, and what size prop would you recomend? In case you aren't familiar, the GP Firebat is an all foam pusher delta wing with canards 31 in span, 31 inch length. Wing area 343 sq inch, listed finished weight 24 ounces so wing load around 10 oz/sq ft.

Also, I'm still waiting for info on my GWS C 47 and any recommendations for use of my 1208 feigo motor previously posted.

Thanks in advance for any help.
Rick
Old 04-15-2007, 10:26 AM
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Default RE: Firebat build

Well, I see a few people have read this, but no replies. However, I figured I'd give an update. I used the lower Kv (980) motor, and put on a prop from an old electric park flyer I used to have. I think it's a 6 incher with around a 4 pitch. The motor was pretty much a drop in substitute for the stock motor. It screwed right into the ply mount exactly where the stock motor would have and fit into the fuse with enough room around it that the can spins freely. I had to route the wires out of the fuse tho because they were in the front (rear) of the motor? Well, they came out of the stationary part of the motor which is attached to the mount and there was no way to route them inside the fuse along the spinning can so I added extensions to them and poked a hole in the top of the fuse forward of where the can ends to bring them back inside to the esc. I did need to add some weight to the nose, but she topped out at 27 onces ready to fly-3 ounces more then the 24 ounces the manual states but I used standard servos and receiver with the brushless motor. I have a line on a 9 inch prop from a Hobbico EP Superstar which I think I may want to try, tho I think she'll fly as is. I took her to the field yesterday but the wind was blowing pretty good so I kept her grounded. Hope to maiden her this week or weekend, and I'll let you know. Anyone with comments or who has done a similar mod I would love to hear from. I am starting a new project today, a B 29. It's one of those small electric ones made to climb and turn with motor power only, but I am changing the receiver out, adding a standard esc and 2 servos for the rudder and elevator. I'm going to start a separate thread for that now.
Rick
Old 04-19-2007, 02:18 PM
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Default RE: Firebat build

The Kv of a speed 400 6v motor is approx 2650 kv or so. you would use a 7 cell Nicad or NiMhd battery (8.4 volts) with a 5 x 5 prop (inches). If you are using a 3 cell Li-Poly battery the higher 1200 Kv motor would use a 9 x 6 to 10 x 7 prop. The props speeds would be in the area of 55-60 mph and the thrust might be as high as 36 ounces. I used a Medusa motor of 1300 Kv to tweak the readings since I do not know what motor you are using, so the actual performance will vary.
Old 04-24-2007, 08:13 PM
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Default RE: Firebat build

This is driving me crazy!!
I got the Firebat ready to fly, but I can't get the motor to carry full throttle!


I have a matched set esc and outrunner motor I bought together on ebay, specs as follows:
ESC: 30A Tower Pro MAG8
current: 25-35 A
FET (whatever THAT is!): 15
Operating voltage: 6-15 volts
Timing Mode (again ????): 3*/8*/15*/30*
PWM (whatever???): 8 khz

Motor (Hong Kong): Kv 1200
Max Current: 30A
Max efficiency: 98%
input: 6 to 22 volt
Prop: 6x4 to 14x6

OK I know these are NOT the high priced spread, but they are what I have, and I can't get the motor to run at full throttle! I am using nimh cells, an Electrifly 8 cell pack, AA cells and 1100 milliamps. When I connect the battery with the transmitter on and throttle down, there are beeps. Sometimes 1, sometimes 4 or 5, and once it just kept beeping! But when the beeps stop (or I get tired of waiting!) and I apply throttle, everything seems fine. The motor comes to life and accelerates nicely up to I'd estimate 85% power. I have left it there and it seems fine and keeps running, but when I push it the last few clicks, it just shuts down. Throttle down to idle and it comes right back on and repeats. It will do this over and over and over! Anybody have any ideas?? I'm tearing my hair out here! I don't know anything about "programing" the esc. Is that it? Nothing is getting hot. The esc gets warm, but not hot. The motor and battery are cool to the touch. I'm spinning a 9 inch prop with a pitch of 7. HELP!!!
Rick
Old 04-26-2007, 07:02 AM
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Default RE: Firebat build

GOT IT!! I think. I did some general searching and found what was purported to be the programming instructions from the Tower Pro website for their Mag series esc's. It was pretty difficult to understand, but I got enough out of it to try something, and now I get (and keep) full throttle with my nimh cells. I think the problem was that the esc was factory set for lipos and since I was coming in with 9.6 volts, it assumed I was using a 3 cell lipo. As soon as the draw went high, the voltage would drop below the 3 cell lipo cutoff and viola', the motor was cut off. As soon as I did what I thought I was supposed to do to to switch the esc to nixx cells, the problem went away.

Sal, does this sound reasonablee to you? BTW, if anyone needs the programming directions (or if you just want them, Sal, just ask. I kept them on my desktop.
Rick

PS: Hope to get the maiden in this weekend. I'll let you know how it goes!
Old 04-29-2007, 08:14 PM
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Default RE: Firebat build

That would do it. The Li-poly cutoff would be too high and cause the speed control to shut down. Let us know how it works now.
Old 04-29-2007, 08:19 PM
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Default RE: Firebat build

It worked great! Plenty of power. Unfortunately, I crashed it good on it's maiden and broke the nose into pieces. So now I am in the process of modding it into a canardless elevon controlled flying wing! LOL.
Old 04-29-2007, 08:33 PM
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Default RE: Firebat build

Sorry to hear about the maiden, but good luck with the mods.
Old 05-11-2007, 07:44 PM
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Default RE: Firebat build

Finished the mods and the Firebat WING flies good.
Old 05-15-2007, 10:21 PM
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Default RE: Firebat build

Good for you! Enjoy!

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