|Aug 02, 2003, 07:01 PM|
Joined Apr 2002
Motocalc won't work need power system help.
I'm once again at square one on the power system for my big bird. It's looking as though I'm going to have to listen to gearbox noise after all. The big Axi is just going to need too many cells, and probably be full bore all the time which means short run times.
Anyway I'm looking for 8-10lbs of thrust. Or the ability to swing a 14x8" prop at 10,000+ rpms. Also looking to do so on the lowest cell count possible. 16 cells or less would be best.
I know a geared endoplasma will hover a 3.5lb plane so I figure a decent brushless should be able to get 8lbs+
Also needs to have a good flight speed it's not a funflyer so a top speed of 50mph does me no good.
If motocalc would run on my system I would crunch it all myself, but it won't. I'm also trying to keep the power system down to $250 or less not counting gearbox or battery. So if the motor, and controller is going to go over $250 it's a no go.
|Aug 02, 2003, 07:53 PM|
This'll get you close
MEC Superbox, 5:1 ratio
Castle Creations 45 amp controller
16 Sanyo 2600's
Per e-Calc this will give you 126 ounces of thrust at a static 46 amp draw. Pitch speed about 50 mph. Amp draw should drop in flight and flight speed should be better than pitch speed if the plane's not too draggy.
MEC has the motor /GB/ ESC combo for $252. They will mount the pinion and gearbox to the motor for no extra charge.
For $20 more you can upgrade to the CC 60 amp controller and it willl also handle up to 20 cells.
20 cells and a 16/10 prop takes the amp draw up to 54, the pitch speed up to 62 mph and the thrust up to 157 ounces. This would be my choice.
Looks to me like one of these will do the job you want done.
Gear box noise is sweet if the plane flies well
|Aug 02, 2003, 08:15 PM|
Joined Apr 2002
Thanks for your help. This is going in a Dauntless WWII dive bomber. It's a conversion I'm wanting to do it's rated for a .60 2-stroke up to a .90 4-stroke with an AUW of 7-8lbs.
It's scale so not exactly an aerodynamic wonder. Big wings, round flat nose etc.
Thats also why the weight is so important. As 16 cells puts me only 1/2 a pound over the glow AUW. Which I think I can shave off with a little effort.
I also fly off a semi-short grass field so it needs adequate thrust to get up and running. Speed isn't that important, but I want to be able to pull big loops, and do strong climbouts.
I'm basically trying to show glow guys, and people looking at electrics that big power systems aren't all that expensive. That and they aren't underpowered.
It's just more effective when the electric power system cost around $250, and a OS .91 4-stroke costs $250+shipping. Plus at 10-12oz of fuel per flight batteries really start to become cheaper when you stay in the lower cell counts.
I just hope I have ground clearance with a 16" prop. I'll most likely go with the CC 60 20 cells, and the 16/10. I won't need full power for anything but big climbs, and take-off. Then I can throttle back for those low scale passes.
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