Michael McGee wrote:
Doing some dreaming..
What do you guys think of the viability of a front cover cast
into
the form
of a standard Lycoming dynafocal-1 mount?
A loose collection of my thoughts so far:
I think it would sell well enough to get the price under $500
for
the
kit. I was bs-ing with the local rotary engine builder the
other
day and
he showed me a very nice third-gen oil pan that was cast as a
replacement
for the stamped steel original. The reason behind the pan is
another story
but the casting work looked great (from this engineer/
non-casting
expert's
perspective anyway). He insists that he has a casting guy that
is
capable
of making what we need if I can get him a proto type part.
The thought here is a Dynafocal mount would open up more of the
market to
those who would CONVERT to rotary engines (like I'm doing) if it
didn't
require changing the motor mount. I realize that we can make a
decent
mount without it and use something like the Schertz beam or the
bell
housing. The Dyna-1 mount would be an effort towards more of a
standardization for aircraft use.
I've been toying with this for the last couple of weeks and
while it
needs
some serious planning for water pump and alternator
accommodations,
I've
got a bit of it worked out. As expected it isn't as easy as
originally
thought. Of course if it was it would already be done. It
would be
supplied as a package with water pump and alternator mount.
This does require using a remote water pump like what Paul
created.
It
gets the pump down lower for better performance. If you use a
3rd
gen
water pump with its own remote pump housing it could be mounted
co-
axially
with the crank and get rid of a water pump drive belt. (3rd gen
pumps run
opposite direction to earlier pumps)
It also would require using the 3rd gen crank angle sensor plate
and
pickups.
There are enough bolts on the front end plate to hold it
together. Additional reinforcements for the aerobatics crowd
would
be
added at the oil pan-to-front cover flange and on the top from
the
EGR port
on the center plate to the top of the motor mount/front cover.
This
would
probably be standard for the 20B motors.
-Could be that the sealing surfaces would be a problem as a
structural
interface?
-It would put the prop flange about 2 inches forward of the
Lycoming
installation. However that would put the 13B c.g. about the
same as
the Lyc.
As an RV-4 owner the thought of a motor mount as compact as the
dynafocal
mount is appealing. Yes, I know it has been done on an RV-4
otherwise. I'm looking at future possibilities.
Okay, enough for now, you guys shoot holes in this for me....
Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR, jmpcrftr-at-
teleport.com
13B in gestation mode, RD-1C, EC-2.
Joseph M Berki wrote:
A dynafocal type mount would benefit narrow airframes like the RV 3
and
RV4, Long EZ. A concern that I wonder if Mistral has addressed, is
hanging the weight of the engine and gearbox on the front end
housing.
How
do the loads affect the engine "block" during flight and flight
maneuvers?
Joe Berki
Limo EZ
Mike and Joe,
Please educate me on this matter. Why would a dynafocal mount be
superior to a conical mount in this application? My understanding is
that the dynofocal mount was designed to minimize the secondary
imbalance in a horizontally opposed 4 cylinder. My design for my RV-4
is similar to a conical mount - am I going to have a problem with
vibration that I can't tune around with the Barry mounts? I have
attached a photo of my mount to refresh your memory. Thanks for your
help.
Ken Powell
No, Ken you are reading too much into this project of mine. My motivation
is solely to create a 13B engine front cover that is a direct bolt on to
any existing Dynafocal-1 mount. There by getting around the need for a
custom motor mount. The D-1 mount is not optimized for the rotary and
would be no better than the conical mount you have created.
What you have created will work just fine. I just happen to have access to
someone who insisted that casting up a new front cover would be easy. Of
course he hasn't spent three weeks trying to model a prototype...
Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR
13B in gestation mode, RD-1C, EC-2
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