Jerry, is the thrust line 10.7 inches down from the top of the
firewall?


Paul Lamar

There it is.  Tailwinders have been raising the top of the firewall for
a long time.  This lowers the angle of the windshield and reduces drag.
  Raise the two corners one inch and raise the center 2.5 inches.  The
top of the firewall is a curve.   Jerry

What is the shape of the curve? If you don't have that tell me how far

above

the thrust line is the center of the curve and how far above the thrust

line

is the curve where it reaches the sides of the cowl. I will then assume
it is an ellipse

Paul Lamar

Jerry,
The Vision designer Steve Rahm is a great admirer of the Tailwind and I
guess it shows in his design.
The firewall is similar and the thrust line is 10.7  same as the Tailwind
(strange that). You will notice the TL -ve 4" to the Level Line i.e. 6.7+4 =
10.7"

I asked Steve if I could lower the thrust line as he moved it up a couple of
inches for another installation and he said SURE a couple f inches won't
hurt as the lower the thrust line the more it offsets the draggy fixed gear
(I figure a couple of inches would be the limit however). I have opted for
another of his suggestion and that is to lower the cowl by 2" for obvious
reasons, of added advantage. I'm even thinking I could place a flap on the
rad baffle to release excess pressure, to control airflow through the rad.

Seeing you have an extra 2 inches to the depth of the firewall ( than mine),
I figure this would be an option if the cowl is still a problem.

It would seem the thrust line is a bit like the CG where it balances out the
drag - never realised that before.

Just a suggestion!
However I also like the last suggestion  where the inlet tubes face forward
on the exhaust side - I'm just not sure how the injectors would be placed.
George ( down under)

 
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