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Author Topic: inrunner motors and planetary gear boxes  (Read 1600 times)

Offline Scott Bauman

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inrunner motors and planetary gear boxes
« on: September 12, 2012, 07:31:24 PM »
I'm a somewhat new member here and have only a couple posts.  I've been searching the forum for info on inrunner motors and planetary gear boxes.
I am building my first CL model (have a Cardinal ARF) and looking to do an electric conversion on a Vector 40 kit.  Before I start building I want my power system layed out and working.

I've been flying electric rc for a bit over 10 years now and build quite extensively and have no problem with construction.  I do have a problem figuring motors for CL models.  I have a couple electric motors with planetary gearboxes on them.  They are motors that could fly a typical 40 sized RC model with no problem.  Has anyone used or have info on various gearbox setups in particular planetary gearboxes?  I am personally partial to geared electric motors for a couple of reasons.  1)more control of the motor output, 2)a crash will usually strip a gear or output shaft that can be quickly replaced. 

-Scott
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Offline Crist Rigotti

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Re: inrunner motors and planetary gear boxes
« Reply #1 on: September 12, 2012, 07:47:36 PM »
Gearboxes for C/L stunt are a no-no.  The "G"'s are too much for them.  Go with an outrunner and save yourself a lot of headaches.

Look here:

http://stunthanger.com/smf/index.php?topic=18251.0

Very easy to find this info if you use the "Search" function.
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Offline Larry Renger

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Re: inrunner motors and planetary gear boxes
« Reply #2 on: September 15, 2012, 11:19:48 PM »
I am curious.  Has anyone actually TRIED an inrunner and gearbox?  I don't recall any reference to such a system being done and failing.  Guess I need to do a search.  :-[
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Offline Dennis Adamisin

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Re: inrunner motors and planetary gear boxes
« Reply #3 on: September 16, 2012, 08:17:10 AM »
Quote from: Larry Renger on September 15, 2012, 11:19:48 PM
I am curious.  Has anyone actually TRIED an inrunner and gearbox?  I don't recall any reference to such a system being done and failing.  Guess I need to do a search.  :-[

Yup.  Worked perfect for 9 flights, failed the gears on flight #10.  Not interested in rebuilding the drive that often.  Later speculation was that substituing a Delron gear MIGHT have been a good thing, I shall leave that for others to try - with all my best wishes.  Hellcat subsequently switched to Outrunner.  Too bad, a fully optimised installation could have kept the motor and pack internal to a 1" thick profile fuse, would have been slicker then a minnow's belly...

I think Tom Hampshire also has had some (bad) gearbox experience.

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Offline Dennis Toth

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Re: inrunner motors and planetary gear boxes
« Reply #4 on: September 21, 2012, 08:31:11 AM »
Scott,
Although the gearbox approach doesn't hold up in our application there is an in-runner that is direct drive that does. Check the Neumotors on the Castle web site. Mike P ran one in his Mustang, don't know if he still has it in that ship but it might be listed in the Set-Up section.

Best,  DennisT
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Offline tom hampshire

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Re: inrunner motors and planetary gear boxes
« Reply #5 on: September 21, 2012, 08:59:21 AM »
Hi Dennis - My experience with gearboxes was the same as Dennis Toth's.  The bending moment on the shaft from inertia, precession, P factor etc. simply overwhelms the ability of the gear housing to hold things together.  And the bearings are not only too small, but far too close together to handle the bending loads.  Mine was tried about 12 years ago, and led to an immediate change to outrunners.  I used 5C Lipo's at that time as well, and could not get sufficient current flow to do any more than loops and wingovers.  If anybody really wants to use a gearbox to get better motor efficiency and a smaller/lighter motor setup,  they should look at a motor frame supporting a hollow jackshaft powered by a gilmer belt, with support bearings at each end of the motor.  As it stands, the outrunners are off the shelf and with some attention to either front mounting or supplemental bearings are very usable.
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Offline Scott Bauman

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Re: inrunner motors and planetary gear boxes
« Reply #6 on: September 23, 2012, 07:30:55 PM »
Wow who would have thought a high quality planetary gearbox would not hold up.  One of my Mega Motors planetary gearbox cost 4 times what a HobbyKing outrunner motor costs.
Here is the webpage for the gear box I have. http://www.megamotor.cz/v4/script/default.php

I'm just not a fan of outrunner motors but will take the experiences of other and stick with an outrunner unless there is a good high quality Hacker or Mega inrunner that will work for a Vector 40.

Thank you very much for all of the replies. 
-Scott
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Offline Peter Ferguson

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Re: inrunner motors and planetary gear boxes
« Reply #7 on: October 21, 2012, 08:23:32 AM »
Love the circular saw kit on the website. Too bad you can't get a price on it. I suspect its currently unavailable. Looks like fun to build.
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Offline Darkstar1

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Re: inrunner motors and planetary gear boxes
« Reply #8 on: October 21, 2012, 11:24:03 AM »
Quote from: Peter Ferguson on October 21, 2012, 08:23:32 AM
Love the circular saw kit on the website. Too bad you can't get a price on it. I suspect its currently unavailable. Looks like fun to build.


62 Euro's Or about 85 USD's
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Offline Tim Wescott

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Re: inrunner motors and planetary gear boxes
« Reply #9 on: October 21, 2012, 11:58:10 AM »
Quote from: tom hampshire on September 21, 2012, 08:59:21 AM
Hi Dennis - My experience with gearboxes was the same as Dennis Toth's.  The bending moment on the shaft from inertia, precession, P factor etc. simply overwhelms the ability of the gear housing to hold things together.  And the bearings are not only too small, but far too close together to handle the bending loads.

I know I'm a late entrant, here, but:

I suspect that this could be done, but only if you redesigned the gearbox to have a good long nose with herky bearings.  It'd probably be necessary to have a good stout output shaft, too.  By the time you were done I'm not sure that you wouldn't have something that's no lighter or more efficient than an outrunner.
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Offline Dean Pappas

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Re: inrunner motors and planetary gear boxes
« Reply #10 on: October 23, 2012, 01:19:14 PM »
Hi All,
If one were to go through the bother of creating a reduction drive, either as Tim or Tom suggest, the benefit of having winding resistances under maybe 15 milli-Ohms (vs 30, 40 or more with outrunners) is that loop gains could be tighter and response times could be faster. There will also be a small efficiency gain of a handful of percent at most.
take care,
  Dean
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Offline RandySmith

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Re: inrunner motors and planetary gear boxes
« Reply #11 on: October 24, 2012, 02:31:33 PM »
Quote from: Tim Wescott on October 21, 2012, 11:58:10 AM
I know I'm a late entrant, here, but:

I suspect that this could be done, but only if you redesigned the gearbox to have a good long nose with herky bearings.  It'd probably be necessary to have a good stout output shaft, too.  By the time you were done I'm not sure that you wouldn't have something that's no lighter or more efficient than an outrunner.

Hi Tim

YOU would be best served designing this as 1 , including  the motor, you can do this lighter and stronger that way


Randy
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