Paul, could you please render a new version of the CH-640
mount(based on the ch-801, but with a lower rear attach
from oil pan rear over the nose gear strut), utilizing the
Doddridge plate, Tracey Cook RD1-C, rear lower oil pan
vibration stabilizer, etc.  (basically all the features of
the final version you sent) but move the plate and engine
out 6" further from the fire wall to accommodate for the
use of the RB light weight center and end plates?  I spoke
with Mathieu Heinz when I picked up the wings in Canada,
discussed the implications of the lighter weight
installation, and his recommendation was to move everything
out 6".

Also could you make notes for me as to the basic
raw construction materials used, like different tubing
sizes, IE diameter and wall thickness.  I have both Q-Cad
and Alibre now, so I should be able to read the cad dwgs
directly.

 Craig Smith

 snips...

 Preliminary motor mount design.

 One of the unanticipated (by me) side benefits of a light weight 200 pound
 (with PSRU & acc.) 250 HP p-port all aluminum engine moved six inches
 forward in the cowl is more room for the cooling system.

 I would also take advantage of the increased net payload by enlarging
 the fuel tanks for more range. Lots of range is a safety factor as
 you could get somewhere and need to go back because of weather.

 You will also need a 3 blade prop to absorb all this HP.

 This airplane is going to blow a lot of peoples minds.
 Excellent short field performance will be all too obvious.

 Paul Lamar


Two hundred pounds with PRSU and acc. ? Is this accurate Paul, I thought
that was an approximate weight for the light single rotors.

John


Well the bare block two rotor came out to 109 pounds.
There is a picture of Doug holding one at 7 Stock on the
front page of the web site.
I guessed at the rest. 45 pounds PSRU. 7 pounds starter
8 pounds alt., etc., etc..

Poorly educated guess :) Probably not including fluids.

------------------------------------------------------
Craig,

What do you think about bracing the cowl area with a couple
of 1/2 inch 4130 tubes to feed rear motor mount loads
back into the longerons under the gull wing doors?

Just think of it as an extension to the motor mount.

Then I can use this top rear mount scheme.

----------------------------------

Update 640 specs etc.

Paul Lamar


I will be sending you 7 pages from the prints, including FW
and Fuselage diagrams. I'm not a qualified engineer, therefore
unable to determine if your alternate solution is safe. Once
you have a look at the prints, and can determine if the
structures are up to the task, I would have no objections
to another approach.
Soon as I get home, I'll get them out to you.
C. Smith


Could you forward these 3D's to your friend at Zenair and
ask them if they have any objections. Perhaps send me his
email address and I will do it.

Paul Lamar