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Old Mar 14, 2011, 05:42 PM
Registered User
USA, CA, Redondo Beach
Joined Nov 2010
53 Posts
Guidance on a replacement 550 motor

First - I have done a lot of searching but I haven't yet unraveled the mystery of interchangeable motors - so any guidance there would be wonderful! I'd love to learn this stuff myself.

Second, here's the deal - I have the Airfield 1450 P-51 with a stock set-up (but for a super-duper replacement BEC) and I bent the prop shaft by being a knucklehead (still trying to learn this one, it's new to me.) Of course, it's nearly impossible to find a replacement prop shaft, so I've given up and am looking to replace the motor.

It's hard to find specs on it - all I know is it's supposedly a brushless 550 - but what does that mean? There are two on the Nitroplanes site (both sold out) - 1) a 520 kV and 2) an 800 kV.

Spent the weekend going to three LHS to find a replacement; no joy.

From the looks of the prop shaft, I think I want the 520 kV. But again, they're both sold out. So I had a look at possible replacements that seem to have similar specs, and these are the ones that are not sold out that might work?

I can tell I'll need a prop adapter, but at least I'll be closer to my goal.


(not powerful enough?)


I don't know that any of those will work. But they seem similar in size. The airplane has I believe a 50 amp ESC, and I have 4S batteries for it. I'd really LOVE to fly the 4-blade prop on it such that it will climb straight up (if that's even possible - I'm not after ridiculous aerobatic performance, but just looking to help myself out of trouble).

Does any of that make sense? Thank you in advance for helping this here n00b. =)

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Old Mar 14, 2011, 06:12 PM
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Corelli's Avatar
United States, NM, Farmington
Joined Jun 2008
840 Posts
You want to know the mount of the new motor will match your old. You want to know how many amps you were pulling with the old motor, so you can be sure the replacement has enough rating . You want KV of old motor.

Once you know those things you can make a better decision .

For instance, if your old motor wasnt powerful enough and you were way under in amp draw you might deduce that you can up the KV of your motor on the replacement .

Or if you are planning to run that 4 blade setup you spoke of but it pulled way too many amps with the old motor you could deduce that you could use a lower KV motor this time.

Alot of these types of decisions arent an A+B=C type of answer.

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Old Mar 14, 2011, 06:17 PM
Reduce the drama...
rick.benjamin's Avatar
USA, OR, Damascus
Joined Apr 2004
4,045 Posts
Toby has a thread regarding this plane.
He used this motor
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Old Mar 14, 2011, 07:14 PM
Registered User
USA, CA, Redondo Beach
Joined Nov 2010
53 Posts
Thank you!

Indeed Corelli, that's the problem. It's really hard to know that stuff with a bent prop shaft and no specs! =)

Rick, thanks! I will definitely check out these threads! I hope they help to answer my questions... should have thought to search on the plane rather than the motor... THANKS! =)
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Old Mar 15, 2011, 02:57 PM
JimNM's Avatar
Las Cruces, New Mexico, United States
Joined Jun 2002
7,447 Posts
FWIW most people will think of 200 watt motor when they see 550... due to the.association with the old maubuchi size codes (400/500/550/600). The motor you are talking about is a whole lot larger and has a Kv of 550 (rpm per volt)
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Old Mar 15, 2011, 04:56 PM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
27,208 Posts
I'm with Jim... "550-motor" to me means a can motor capable of maybe 20A on 3s.
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