The problem is the lip at the bottom of the firewall (unless,
as some do, you install the firewall the other way around ..).
Because of the slope of the firewall, the air flows tightly down the
front of it, and runs into that lip, causing a swirl, drag, and
obstructing the clean exit of air from the cowling.
The fix is to smooth the lip, rounding it. Picture a piece of
.020 the full width of the fuselage, extending back about 3 "
behind the firewall, fastened to the belly. It also extends
forward of the firewall by about 5 or 6". Now wrap that
front part up and back until it touches the firewall - and
rivet it there ! This makes a smooth ramp over the sharp
lip, and smooths the airflow. It will definitely lower all
temperatures. On the RV series of aircraft, it also gains
about 10 mph !!! Unfortunately, the speed gain for the Rebel is
barely noticeable.... ;-) :-)
I know it is VERY difficult to add this lip fairing after the
Rebel is finished, but you can clean up large parts of the lip
with lots of careful snipping & trimming, around the engine mounts
and gascolator ....
..... and you can fill in a lot with that metal adhesive tape
that body shops use for holes ! ;-)
......bobp
-------------------------------orig.-------------------------
On Monday 06 June 2005 10:09 pm, IAN DONALDSON wrote:
** Check your subject, does it still reflect the message? **
G'day
I read with interest this post regarding firewall fairing.
Would someone please explain in detail how this was done?
Are there any pictures in the archives?
regards & thanks
Ian Donaldson
Hey Neil, One other thing to do is make sure that you have faired the lip
of
the firewall. About 2" up on the firewall gave me almost 15deg f. ya gotta
keep the airflow smooth going out too. >
-----------------------------------------------------------------
List archives located at: https://mail.dcsol.com/login
username "rebel" password "builder"
Unsubscribe: rebel-builders-unsubscribe@dcsol.com
List administrator: mike.davis@dcsol.com
-----------------------------------------------------------------
