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Thrust Line ?

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Old 01-03-2005 | 02:34 PM
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Default Thrust Line ?

I have over the past year had 3 different engines in my Black Horse Travel Air. On each engine installation I have had a different orientation for the set up. I have had to re-drill the firewall to acomplish this and have filled/glued each old hole with dowl so not to weaken the firewall. I have now installed yet another engine and its orientation is "normal" i.e. head at the top. I have had to lower the engine mount because I can't get the tank any higher.

Is the Thrust Line a vertical line through the centre of the firewall or a horizontal line??

Can I mount the engine too low on the firewall and will this adversely affect my plane?? (The pre cut hole in the firewall is roughly the centre of the mount).

Does it really matter??
Old 01-03-2005 | 02:42 PM
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Default RE: Thrust Line ?

ORIGINAL: MerlinL14

I have over the past year had 3 different engines in my Black Horse Travel Air. On each engine installation I have had a different orientation for the set up. I have had to re-drill the firewall to acomplish this and have filled/glued each old hole with dowl so not to weaken the firewall. I have now installed yet another engine and its orientation is "normal" i.e. head at the top. I have had to lower the engine mount because I can't get the tank any higher.

Is the Thrust Line a vertical line through the centre of the firewall or a horizontal line??

Can I mount the engine too low on the firewall and will this adversely affect my plane?? (The pre cut hole in the firewall is roughly the centre of the mount).

Does it really matter??
.
As long as you sorta maintain the horizontal location of the thrust line, you won't see much difference in the way the plane performs.
Prop clearance would be my worry, more than anything else.
Old 01-03-2005 | 02:59 PM
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Default RE: Thrust Line ?

The thrust line runs longitudinally & is (or is not) displaced laterally & vertically, and is (or is not) angled laterally and vertically. In other words it generally points down the long axis, but can be angled up or down, & right or left, & can be "bodily" shifted up or down and right or left. Got it?
Old 01-03-2005 | 03:08 PM
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Default RE: Thrust Line ?

The thrust line is the direction in which the crankshaft of the engine is pointing.
Minor adjustments to its position will make no noticable difference, as Tall Paul said.
Old 01-03-2005 | 03:18 PM
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Default RE: Thrust Line ?

@ Tall Paul, horizontal plane is as stock, no probs with prop clearance.
@ Britbrat, LMFAO
@ Alasdair, sorted.

Thanks for your quick replies fella's. Happy new year.
Old 01-03-2005 | 04:26 PM
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Default RE: Thrust Line ?

The thrust line as I understand it is the longitudinal datum line,
both horizontal and vertical, that the air frame desinger used
as the base from which he aligned the other components of
the air frame, most importantly, the wing, stab and rudder.
In aligning a motor you would like to know
what the designer had in mind so you can set the motor such
that it "pulls" as he expected it to relative to this line - and yes
this "proper" alignment may be ofset up/down/laterally and
alsom, very commonally, at an angle (in order to induce some right thrust).
Just my understanding. Hope it helps
Bruce
Old 01-12-2005 | 03:38 PM
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Default RE: Thrust Line ?

It really turned out to be a non eventl. I flew the plane on Sunday and other than having to add a bit of down elevator from my "normal" trim it flew OK. Rolls and exiting from inverted looked a bit ploppier, but it's a £50 model so I can live with it.

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