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Old Jun 22, 2010, 01:33 PM
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mikmerl's Avatar
Athens, Greece
Joined Apr 2010
454 Posts
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Make your own CFK firewall/motor mount for electric gliders

I recently decided to build two small electric gliders that I have had since the mid 90’s and never got around to building. These initially had plywood motor mounts up front to facilitate mounting brushed motors w/reduction drives.
I soon realized the two AXI outrunners that I purchased would not fit as the three wires exiting out of the side of the motor would not fit within the nose ring so far forward. I saw some solutions in various forums where guys would drill a hole in the side of the fuselage for the cables to exit and then another one a bit further aft for the wires to renter the fuselage to be connected to the ESC.

I preferred to flip the motors and mount the prop on the rotating (magnets) can with the appropriate adaptor so that the motor wires will now exit at a point where the fuselage has widened substantially and can accommodate them easily. This however called for a new relocated firewall/motor mount.
  • I measured the fuselage at the point where the new firewall was to be installed and drew this using a Cad program.
  • I then printed it on self adhesive A4 paper and applied it on to a piece of 1.5mm CRP.
  • Next I cut out the new firewall and did some trial fitting to ensure that it was snug in its final position including any down and side thrust.
  • I screwed the motor to its new mount and installed the prop and spinner as well.
  • Insert the complete unit into the fuselage and carefully aligning the spinner and the nose ring until it lines up giving the desired thrust angles I tack glued the mount in place.
  • Then the motor was removed and the mount firmly glued in place with epoxy resin and glass chop.
As can be seen in the photos I relieved the mount of access material not so much for weight reduction (you usually need weight up front) but to aid in air cooling for the motor, esc and also the battery.

The result is extremely light and very strong, giving a smooth true running motor. (I was pleasantly surprised by how smooth and powerful these AXI’s are)

The photos should be self explanatory and I hope that this “how to” may be of some use to somebody with a similar need.
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Last edited by mikmerl; Jun 22, 2010 at 01:43 PM.
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Old Jun 22, 2010, 06:39 PM
"No" means "Know"!
USA, CA, Los Angeles
Joined Sep 2004
568 Posts
Nicely done! I usually struggle to hot glue the motor wires to the side of the fuselage and am forced to use smaller diameter, less powerfull motors to get enough clearance. One note, though, with the mount so far back from the prop, vibration from any imbalance in the blades would be amplified. With careful assembly and blade balancing, this should be a winner.

Thanks for sharing,

Mike.
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Old Jun 23, 2010, 02:13 AM
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Europe - Belgium
Joined Mar 2005
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Nicely done!
Just make no nose bump landings, as there are only 4 spots of glue.
Good luck, J.
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Old Jun 25, 2010, 11:06 AM
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Indianapolis, IN USA
Joined Nov 2000
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http://www.aircraft-world.com/shopexd.asp?id=7159
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