Paul and Vance,
I don't want to start an argument and was only trying to help! as the
top of
the Kis installation is very tight, as you have stated so many times
before
Paul.
 Like you said the RV's have a better chance of fitting everything in
especially the manifold, over the top of the engine.

To state some figures the Tailwind is tight with it's thrust line at
6.75"
( I believe) - which is exactly the same as the Vision.

Having said that the Kis is 8.5" -  a good 1.75" lower.

Advice to me is that the lower the engine weight the better!
Engine weight lower = thrust line lower, unless you use an off-set
PSRU.

Like you said Vance 'thrust lines are not set in cement' - and in the
case
of the Vision the Thrust line can be anywhere from 6.75" to 10.75" or
4 "
lower. I would suggest this MIGHT also be the case for the Tailwind,
Jerry.

Having said this very few planes are designed for the Rotary
installation,
except for the Cosman I don't know of any others which specifically
target
the Rotary installation.

To my knowledge most aircraft are designed to accommodate the
Lycoming or
Continental - industry standard !?

The Kis being a relatively new aircraft, I thought might consider
automotive
installations and make the thrust line lower, with the facility to
raise it,
thereby providing for more prop clearance, with sufficient in the
worst case
scenario. I was surprised to find this wasn't the case.

Anyhow there you have it, all the information available to me - to my
way of
thinking if you need the room and you can lower the thrust line, the
lower
engine weight is better.

George (down under)

George,   When you say the thrust line is at a certain height we need
to know the reference water line or else what are we talking about.
To talk about the Tailwind  the center of thrust is 10 inches below the
top longerons and 15 inches above the bottom longerons at the firewall
station of course. This does not tell us much about clearance above the
engine because the firewall top is above the top longerons and the
bottom is below the bottom longerons.  If I needed another half inch
above the engine, I would  add more height to the firewall.   Nearly
every TW built in the last ten  years has had the firewall height
extended.  I added 2.5 inches to mine.  It makes the windshield lay
down for better aerodynamics and provides room on top of the engine too.

I would not hesitate to lower or raise the engine to get the room
needed.  The limiting factor is prop clearance.  We are going to be
generating so much power with the p ports and turbos  and 2:85s  that
the 3 blade prop will be a necessity anyway.  That ought to get back a
couple of inches of ground clearance.

    Jerry

Jerry,
I remember you saying about adding height to the firewall.

The WL might be different in as many different designs, I was trying to keep
it simple by saying there is some flexibility to the thrust line.

The WL 0 in the Vision is 6.75" from the top of the firewall - I believe the
TW is the same.
The Vision has a capacity to cater for different  installations resulting in
the thrust line varying between WL 0 ( top) or anywhere to 4 " below that
line (may be more ?).

It just seems crazy to me that someone would raise the firewall and all the
other modifications when all that's needed is to lower the engine and
balance that against the prop clearance and length of the landing gear.
However it may be easier than I imagine.

Anyhow you be the judge - all I'm saying is that there is an option !

I thought I had a copy of the TW firewall but couldn't find it - I now have
a copy of the Kis to compare, could you send a copy of the TW again, I will
keep them all together for reference.
TIA
George (down-under)

 
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