gearbox suggestion
10-29-2003, 06:02 PM
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gearbox suggestion
I'm getting an SR Bantam Biplane, but I don't know what gearbox or even gear ratio to use.
http://www.srbatteries.com/bantam.htm
Stock seems to be a 280 equivalent (GWS DXA motor), with a 5.9:1 gearbox, turning a 9x4.7 prop on a 7 cell 190mah NiCd pack.
I am planning on using a 380 (I think, it came from a Hobbyzone Aerobird) and either a 6 or 7 cell 900mah pack and I need suggestions for gearing and prop. Should I use the same configuration? BTW, is this 380 considered 300-size or 400-size? I'm doing this on the assumption that the 380 will give me more power.....am I wrong? Is this doable, or should I just go and get the suggested power system?
P.S. This is a 3 channel airplane (T, E, R) but I plan on adding ailerons. I am guessing this will be slightly on the heavier side of the weight range, in my configuration.
ANY comments are helpful, and thank you.
http://www.srbatteries.com/bantam.htm
Stock seems to be a 280 equivalent (GWS DXA motor), with a 5.9:1 gearbox, turning a 9x4.7 prop on a 7 cell 190mah NiCd pack.
I am planning on using a 380 (I think, it came from a Hobbyzone Aerobird) and either a 6 or 7 cell 900mah pack and I need suggestions for gearing and prop. Should I use the same configuration? BTW, is this 380 considered 300-size or 400-size? I'm doing this on the assumption that the 380 will give me more power.....am I wrong? Is this doable, or should I just go and get the suggested power system?
P.S. This is a 3 channel airplane (T, E, R) but I plan on adding ailerons. I am guessing this will be slightly on the heavier side of the weight range, in my configuration.
ANY comments are helpful, and thank you.
10-29-2003, 09:58 PM
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RE: gearbox suggestion
Yes, the 380 is a Speed 400 and in my view way too heavy for a Bantam. A 380 with gearbox and prop will be over 100g - the recommended DXA complete is 34g - do the math - and stay with the recommended motor (Larry Srbnick knows what he is talking about!!!)
Using LiPoly cells I've got my Bantam Bipe down to 221g (<8oz). I can't imagine trying to fly it at 2-3oz (25-30%) heavier! You might be able to use an IPS Dual motor (52g with prop etc) to get about twice the power for only an 18g weight increase. Otherwise go for a Razor/GWS g.box combo and tear the wings off it.
Cheers, Phil
Using LiPoly cells I've got my Bantam Bipe down to 221g (<8oz). I can't imagine trying to fly it at 2-3oz (25-30%) heavier! You might be able to use an IPS Dual motor (52g with prop etc) to get about twice the power for only an 18g weight increase. Otherwise go for a Razor/GWS g.box combo and tear the wings off it.
Cheers, Phil
10-30-2003, 12:45 AM
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RE: gearbox suggestion
OK, a couple things then....
1.) would Direct Drive be any better? If so, what prop?
2.) Would a 9.6V (8 cell) battery burn out the 280? I've got 3 of these from my little Tyco R/C cars. For that matter, would it burn out a 380?
If you're asking why on earth I'm even considering this, I'm a poor college student trying to save money and have fun with friends at the same time - difficult at times. And, remember, I'd like to put ailerons on this, so I'm looking for a little more power. Also the receiver is the mirco 555, not the feather one.
1.) would Direct Drive be any better? If so, what prop?
2.) Would a 9.6V (8 cell) battery burn out the 280? I've got 3 of these from my little Tyco R/C cars. For that matter, would it burn out a 380?
If you're asking why on earth I'm even considering this, I'm a poor college student trying to save money and have fun with friends at the same time - difficult at times. And, remember, I'd like to put ailerons on this, so I'm looking for a little more power. Also the receiver is the mirco 555, not the feather one.
10-30-2003, 07:58 AM
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RE: gearbox suggestion
Direct drive in most cases is worse. Direct drive, a prop will always be smaller and always spin faster. The faster a propeller spins, the more inefficient it gets. The smaller a prop is, the less thrust it can make. The only time you want to go with a direct drive is if you have a sleek, fast plane or certain kinds of brushless motors that are designed to spin large propellers direct drive.
Would a 9.6V battery burn up the 280? Well, this plane is designed for the GWS IPS a.k.a. "DX" drive. By no means is this motor any equivalent to a Speed 280. They're much smaller. These little motors do not hold up well on 9.6 Volts, and the Tyco packs I've seen at Wal-Mart are much too heavy for a plane that's designed to weigh only 8 oz.
You need to be VERY careful with weight. Add ailerons, a heavy Speed 400 motor, and a heavy Tyco battery pack to a plane that wasn't designed for all that additional weight, and you could be in for some major disappointment.
Would a 9.6V battery burn up the 280? Well, this plane is designed for the GWS IPS a.k.a. "DX" drive. By no means is this motor any equivalent to a Speed 280. They're much smaller. These little motors do not hold up well on 9.6 Volts, and the Tyco packs I've seen at Wal-Mart are much too heavy for a plane that's designed to weigh only 8 oz.
You need to be VERY careful with weight. Add ailerons, a heavy Speed 400 motor, and a heavy Tyco battery pack to a plane that wasn't designed for all that additional weight, and you could be in for some major disappointment.
10-30-2003, 08:39 AM
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RE: gearbox suggestion
It's not a 280? hmm....That was my whole premise...[:'(]
Just so we're clear, the DXA (DX-AXC) is here
http://www.gws.com.tw/english/produc...system/ips.htm
5.86 gear ratio, 4.55oz thrust with EP1047 prop, 1.06oz weight
If I want a little more power, could I simpy get the DX-CXC? It has 8.6 gearing and the thrust would be 5.19oz. I don't see how I could go wrong with THAT, since they're all the same weight....all that would happen is it would go a little bit slower, right?
how much thrust do I need? can i run that one on 8.4V as well? (to make use of my other battery)
Just so we're clear, the DXA (DX-AXC) is here
http://www.gws.com.tw/english/produc...system/ips.htm
5.86 gear ratio, 4.55oz thrust with EP1047 prop, 1.06oz weight
If I want a little more power, could I simpy get the DX-CXC? It has 8.6 gearing and the thrust would be 5.19oz. I don't see how I could go wrong with THAT, since they're all the same weight....all that would happen is it would go a little bit slower, right?
how much thrust do I need? can i run that one on 8.4V as well? (to make use of my other battery)
