Thrust

- S
- Stan
  
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posted
17 years ago

Fri, Jul 30, 2004 6:21 PM

t On a Sig 4-star 40 kit the fire wall is marked with a thrust line. How
important is the horizontal thrust line. I want to know if I can lower
the engine about 1/2 inch.
Thanks.

- B
- Bill Fulmer
  
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posted
17 years ago

Fri, Jul 30, 2004 6:49 PM

I wouldn't recommend it.... The 4*40 has very little roll coupling in yaw, and changing the thrust line could have a negative effect on this..
Bill

- D
- Dr1Driver
  
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posted
17 years ago

Fri, Jul 30, 2004 7:20 PM

Changing the thrust line MIGHT affect the axiality of the rolls, but unless you're doing precision aerobatics, who cares?
On the other hand, if lowering the thrust line may make your engine run better, thus preventing an untimely flame-out, then by all means, go for it! Dr.1 Driver "There's a Hun in the sun!"

- M
- Mike Wizynajtys
  
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posted
17 years ago

Fri, Jul 30, 2004 8:57 PM

It's an easy enough thing to test out. The plane won't be uncontrollable with the thrust line moved 1/2" down. Try it both ways to see which you like it best.
Wiz
Stan wrote:

- P
- Paul McIntosh
  
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posted
17 years ago

Fri, Jul 30, 2004 10:47 PM

You probably won't notice the difference.
-- Paul McIntosh

- S
- Stan
  
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posted
17 years ago

Sat, Jul 31, 2004 2:18 AM

Thank guys , I think I will moveing it down a 1/2 inch. Will let you know what happens .
Paul Mc> You probably won't notice the difference.

- M
- MJC
  
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posted
17 years ago

Mon, Aug 2, 2004 1:09 PM

On that kind of aircraft, a 1/2" won't make any measurable difference. For the most part, stay with the design parameters (including the thrust line), however, if you have a good reason to change something, well, experimentation is part of the hobby. In this case, flight qualities won't change much.
MJC

Thrust

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