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  • May 23, 2022, 09:42:53 AM

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Author Topic: First rear mount motor.  (Read 534 times)

Offline Dennis Toth

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First rear mount motor.
« on: December 29, 2021, 12:18:51 PM »
I am getting back to finishing up a Barnstormer that is set up as a take-a-part using the Paul W - Impacted approach. Since the wing and stab come off, I decided to build a second fuse with electric power. As I look at the room available in the nose the best motor mounting option seems to be a rear mount. This will be my first rear mounted motor installation. The plan is to use 3/16" plywood I normally use for my front mounts and do the rear mount with small counter sunk wood screws in through the fuse sides. I'll use 1/32" plywood doublers and will have 1/4" nose blocks from the motor mount former forward to the nose that will be shaped to a 1 3/4" spinner. I'll also put 1/4 triangle supports on the rear of the mount/fuse. I plan on having a top block hatch to install the motor bolts/ESC/Timer/battery and safety switch.

Anything I missed for the rear mount?

Best,     DennisT

Offline Ken Culbertson

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Re: First rear mount motor.
« Reply #1 on: December 29, 2021, 06:57:38 PM »
AMA 15382
If it is not broke, don't fix it.
USAF 1968-1974 TAC

Offline Dennis Toth

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Re: First rear mount motor.
« Reply #2 on: December 29, 2021, 07:04:40 PM »
Looking at the mount, I take it you mount the X mount to the motor then mount the X/motor unit to the firewall (with hole in the firewall for the motor shaft)?

Best,   Dennist

Offline Ken Culbertson

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Re: First rear mount motor.
« Reply #3 on: December 29, 2021, 08:43:38 PM »
Looking at the mount, I take it you mount the X mount to the motor then mount the X/motor unit to the firewall (with hole in the firewall for the motor shaft)?

Best,   Dennist
True, but it is not the motor I am concerned about cooling.  If it is a Barnstormer then it is going to be pretty well exposed.  It is the battery and the other goodies that are in the fuselage.  With a removable wing, you are pretty restricted.

Ken
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USAF 1968-1974 TAC

Offline Dennis Toth

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Re: First rear mount motor.
« Reply #4 on: December 30, 2021, 07:48:06 AM »
Doing some layout work this morning, this is becoming more complicated then I first though. I am building the Box photo shaped nose version of the Barnstormer. the IC version has a hatch the goes over the engine and tank area where you can get full access to the engine mount bolts and tank. For the electric fuse with the rear mount getting access to the X bottom mount bolts is a problem. In order to get the motor in and out you need to either have a removable nose cowl ala Zilch style (the simplest but I don't like the look) or have a bottom and top hatch (again not the smoothest look) or a couple of access bolt holes in the bottom block (similar to normal cowl bolt holes). The concern with the bottom block access holes is getting the mount bolt in place to tighten.

Any other way of doing this? Anyone have photos they could post to show rear mount installations with cowl would be great.

Best,   DennisT

Offline Ken Culbertson

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Re: First rear mount motor.
« Reply #5 on: December 30, 2021, 01:23:11 PM »
Doing some layout work this morning, this is becoming more complicated then I first though. I am building the Box photo shaped nose version of the Barnstormer. the IC version has a hatch the goes over the engine and tank area where you can get full access to the engine mount bolts and tank. For the electric fuse with the rear mount getting access to the X bottom mount bolts is a problem. In order to get the motor in and out you need to either have a removable nose cowl ala Zilch style (the simplest but I don't like the look) or have a bottom and top hatch (again not the smoothest look) or a couple of access bolt holes in the bottom block (similar to normal cowl bolt holes). The concern with the bottom block access holes is getting the mount bolt in place to tighten.

Any other way of doing this? Anyone have photos they could post to show rear mount installations with cowl would be great.

Best,   DennisT
Is it too late to go through the firewall and mount the motor on the rear with the blind nuts in front?  This is mine from my Endgame.  You slide the motor in from the rear.  Bob Hunt put me on to this.  With the open hatch on top it should give you room with the other goodies out.  It does set the motor back the thickness of the firewall so you might need an extension on the shaft unless it is not too late to move the firewall.  If I come across a picture with the motor in I will add it.

Ken

Found one!
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Offline Dennis Toth

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Re: First rear mount motor.
« Reply #6 on: December 30, 2021, 02:01:03 PM »
Ken,
Thanks for the photos and you input. I got a PM from my friend Charles with similar suggestions. I was thinking about it I think I can just mount the motor to the mount former without the X mount similar to what I would do for the front mount. This saves 1/8" which in this ship getting the battery in the nose is tight. The bolt circle for the motor alone is smaller than for the X mount and easier to get to from the rear with the battery hatch. With the 1 3/4" spinner I intend to shape the nose to there is about 3/16" left in the nose ring which gives room to pull the BadAss motor forward enough for the shaft to clear the former.

I think this will work so I'm going to frame it up and see how it looks.

Best,     DennisT

Offline Ken Culbertson

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Re: First rear mount motor.
« Reply #7 on: December 30, 2021, 02:46:51 PM »
Sometimes it is the "Duh" moment.  Mount the "X" frame on the front without the motor attached to it.   Make sure the center hole is big enough to clear the bolt pattern for the motor (the tapered holes).  Now slide the motor in from the front and bolt it to the x frame from the rear. 

Ken
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USAF 1968-1974 TAC

Offline Kim Doherty

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