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Old Jun 18, 2012, 02:54 PM
Thermalin is offline
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I'm a pilot, 100 yrs too late
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Question

Down and Right Thrust on non-angled firewall


With a firewall set square to the fuselage for both side and top views, how does one use washers to set in down and right thrust.

Two washers at top of motor mount would provide down
Remove those and putting
Two washers on the left side would provide right thrust

How do you install right "and" down thrust using washers.
Having a different # of washers in all corners (say 3 in top left, 2 in top right and bottom left and 1 opposite the top left) would direct the nose of the motor down and to the right, but not really provide the same thrust angle as a purpose built firewall. Is that correct or do they both accomplish the same thing.ll
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Old Jun 18, 2012, 05:17 PM
epoxyearl is offline
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Answer # 2 is the Winnah ! " lemme tell you how I do it."!.......
I stand the fuse vertically,on it's tail,supported of course.....then I take 4 'loose' bolts,and install from the rear of the mount,but on TOP of the firewall,not through it.With a nut on each bolt,it's easy to "adjust" the down and right thrust.

Measure from the firewall to each corner of the mount,and fill the spaces with the proper amount of washers to be added when the engine is bolted in place permanently.One corner will always need only one washer.....

If a band saw is available,cutting a hardwood wedge is my preference over washers......doesn't matter though.....washers is good.
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Old Jun 18, 2012, 05:23 PM
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Right and or down thrust, is right or down thrust. It doesn't matter how you get there.

Ken
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Old Jun 18, 2012, 06:15 PM
Thermalin is offline
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Quote:
Originally Posted by epoxyearl View Post
Answer # 2 is the Winnah ! " lemme tell you how I do it."!.......
I stand the fuse vertically,on it's tail,supported of course.....then I take 4 'loose' bolts,and install from the rear of the mount,but on TOP of the firewall,not through it.With a nut on each bolt,it's easy to "adjust" the down and right thrust.

Measure from the firewall to each corner of the mount,and fill the spaces with the proper amount of washers to be added when the engine is bolted in place permanently.One corner will always need only one washer.....

If a band saw is available,cutting a hardwood wedge is my preference over washers......doesn't matter though.....washers is good.

Apologize... but I'm having trouble understanding the purpose of the bolts running through the mount from the back but on top of the firewall, with the nut threaded on the protruding bolt??

the bolts from the rear are threaded fit.. so they can be screwed in and out forcing the mount to angle as needed?
Old Jun 18, 2012, 07:04 PM
Molle is offline
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Quote:
Originally Posted by Thermalin View Post
With a firewall set square to the fuselage for both side and top views, how does one use washers to set in down and right thrust.

Two washers at top of motor mount would provide down
Remove those and putting
Two washers on the left side would provide right thrust

How do you install right "and" down thrust using washers.
Having a different # of washers in all corners (say 3 in top left, 2 in top right and bottom left and 1 opposite the top left) would direct the nose of the motor down and to the right, but not really provide the same thrust angle as a purpose built firewall. Is that correct or do they both accomplish the same thing.ll

Back in the day, I know i used to be lazy and just use washer(s) on the top left bolt to get both right and down at the same time, there's prolly a gazillion more scientific approaches but.. I always favoured KISS.

Easy to adjust if you want more/less thrust.
Old Jun 18, 2012, 08:10 PM
epoxyearl is offline
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Quote:
Originally Posted by Thermalin View Post
Apologize... but I'm having trouble understanding the purpose of the bolts running through the mount from the back but on top of the firewall, with the nut threaded on the protruding bolt??

the bolts from the rear are threaded fit.. so they can be screwed in and out forcing the mount to angle as needed?
Those bolts just "sit" the mount at the correct angle ,as you adjust the nuts to get the down and right required....Once measured for washers,remove those temporary bolts and place the washers on the "real" ones as you reassemble.
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Old Jun 18, 2012, 08:34 PM
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i see now.. i was over thinking it.

Molle.. i was thinking of doing that but there is no way to keep the top right and bottom left from rocking as you tighten down. I think you have to have something under those corners.
Old Jun 18, 2012, 08:50 PM
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i see now.. i was over thinking it.

Molle.. i was thinking of doing that but there is no way to keep the top right and bottom left from rocking as you tighten down. I think you have to have something under those corners.

Depends what the mount is made of really, this is what I used to do with the old glow motor mounts, and they had enough flex in them to be able to tighten all corners.

All depending on time and effort, i guess you could balance the washers on 4 points, 2-3 top left, 1 top right, 1 bottom left, or, whatever works in terms of balance for mounting

I'm pretty sure i used the same technique for a couple of old old 480 motors as well on gliders that i electrified, but then again, its all about how much time and effort you want to use. Customising a motor mount mounting piece would probably be the most elegant solution, but... time and effort
Old Jun 18, 2012, 08:59 PM
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Talking about "overthinking" if you're using a glass-filled mount,you can just grind off what you don't need,if it's a one piece mount>
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