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CarbonXtreme . Midland Helicopters . Modefo's RC Helicopters

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e-Electric Motors & Controllers > Do I need a different motor?
 
 
darkfa8
Key Veteran
Location: Eatontown, NJ, USA

I have:

Jazz 40-6-18
Scorpion HK-2221-10 V2 3000kv
Pinion 10t
Mini Titan stock plastic head
Align Pro Wood 325 blades
4s2100 CellPro Revolution lipo

Data aquired with Eagle Tree MicroPower with Brushless RPm Sensor

At 60% throttle I get 2890 RPM. At 80% I get 3240rpm with the pinion removed (prolly close to 3100rpm at the head)

I think due to the blades I'm trying to run and the plastic head, that I should try and get closer to 2600-2800?

If that's the case, am I right to assume that I need a lower KV motor? Like the -12 (2580KV I beleive)

- Dan G. -
02-16-2008 02:35 AM
HOMEPAGE  
 
 
helimatt
Key Veteran
Location: Lafayette, IN

I agree that you probably should avoid running the wood blades above 2800 rpm, but some have done so routinely without failure, but others have had failures, so I'd avoid it.

the plastic head should be fine- its pretty stout. If you want to run such a powerful setup, why not switch to carbon blades? HDX carbons (like $24-28) or Align or Radix or (go for it) V-blades.

Anyhow, you could look for a 9T pinion, but I doubt you could find one.

Never, ever, ever, ever give up.
02-16-2008 03:46 AM
 
 
darkfa8
Key Veteran
Location: Eatontown, NJ, USA

I'm trying to keep my blade cost down while I'm learning, but I do want a bit of "pop" to help get my butt out of trouble.

I did find some $19 hyperion take-off blades, I might go for these at some point to try.

- Dan G. -
02-16-2008 03:57 AM
HOMEPAGE  
 
 
Richardmid1
Senior Heliman
Location: Leeds, England

If you go with the Scorpion HK-2221-12 and an 11T pinion you should be able to up your throttle curve to nearly 100% in idle up and keep your headspeed below 2800, this will also make it more efficient and you will get longer flight times as a result.

Eat, sleep, 3D, crash, repair, repeat...
03-06-2008 04:10 PM
 
 
darkfa8
Key Veteran
Location: Eatontown, NJ, USA

I bought a HK-2221-10 and put on a 10t pinion and at 60% throttle I get a bit over 2900 rpm.

I might try the -12 to see if I can optimize efficiency of the Jazz by upping the throttle percentage, but I'm not even sure if I'm going to notice a difference. I'll hopefully try it soon and see how the results turn out.

It seems to be a balance between running a high KV motor on a small pinion with as high a throttle % as possible to achieve the desired headspeed. The -10 gets me pretty close, just a tad higher then I'd like, but I may stick with it for now until I experiement with a -12.

- Dan G. -
03-06-2008 05:23 PM
HOMEPAGE  
 
 
mikeflyz
Senior Heliman
Location: Westlake Village, CA

Why not 3S? You've essentially knocked out one cell with that low throttle curve.

Mike
MA Fury Extreme, Logo 600 and T-Rex
03-18-2008 08:57 PM
 
 
S76 Mech
Elite Veteran
Location: Hatboro, Pa.

kinda wondering the same thing, why would you have a kickass setup like that motor, esc and pack, then limit its performance with such a low pinion?

~ Rick
Them Sireens did this to Pete. They loved him up and turned him into a horny toad
03-18-2008 10:14 PM
 
 
darkfa8
Key Veteran
Location: Eatontown, NJ, USA

a small pinion, high KV motor is more efficient.

i haven't found any scientific proof that running the Jazz at this throttle percentage is a bad thing, except that Mike Franz of Kontronik said that 80-85% is optimal.

I may drop down to the -12 motor, at 2585KV I beleive and see what that nets me.

Now though, I think these CellPro 18C packs just don't have the grunt to make this thing more of the animal I anticipated it to be. I'll get to get some 25C+ packs and see what happens.

- Dan G. -
03-19-2008 01:50 AM
HOMEPAGE  
 
 
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e-Electric Motors & Controllers > Do I need a different motor?
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