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
Michael McGee wrote:
Narrow airframes yes, but also looking at the conversion market. Those
with existing Lycoming installations on dynafocal mounts would be more
easily swayed to convert to a rotary if it was more of an engine swap as
opposed to firewall forward project.
This is also my concern. Structurally, would 6 Gs affect the engine
assembly? For this reason I have a plan for a top plate that ties the
motor mount/front cover to the center plate in the engine. I'm calling it
the aerobatic plate for now. I don't know that it will be necessary for
normal or utility category aircraft. Probably for a 20B it would be
needed. All this is speculation as I have not done any calculations yet.
Curious now..is the dynafocal mount on the 6 cylinder Lycoming the same as
the 4 cylinder mount? It seems that the 6 cylinder should use the
dynafocal-2 with the 18 degree focus. The dynafocal-1 is 30 degrees.
Mistral has many modifications to the engine parts. I'm sure they
redesigned the front end plate (accessory section end plate) so it
accommodated the engine mount requirements. In fact if one is making end
plates for aircraft use it looks like it would be preferable to put the
dynafocal mounts in the end plate instead of the front cover. As you can
see from the Mistral engine pictures it squeezes a lot inside the dynafocal
ring.
My front cover/motor mount design is still in the Styrofoam prototype
stage. I keep looking at the front plate I have and wanting to drill out
the tension bolt holes and continue the tension bolts into the front
cover. There's always something you can do just a little bit more...
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