Paul:
When a builder wants to install a Lyc or Cont on his airframe, he
knows there
are existing motor mounts already available, the prop flange comes
with the
engine and, with some flexiblilty, most props are readily available.
It seems to me that making the rotary engine more popular with
homebuilders, a
certain "off the shelf" attraction needs to be added. Instead of
each builder
having to fabricate and modify existing automotive components, or just
downright CNC some parts to make things work, would there be a
marketable
benefit to simply buying a ready-made, reliable PSRU for the 13B
endhousing?
With this in mind, I have contacted a mechanical engineer and a
composite
gearbox source. Initial cost is high to design and develop my PSRU
but I sat
back and thought, "wouldn't this gearbox fit everyone else's 13B"?
Maybe by
producing them for sale, I can spread the initial cost around.
So, my question is, what is the perfect PSRU to mass produce? I've
been thru
the relevent sections on AREN and have come up with the following
wish list. I
hope the readers here can to add to this list, giving me their input
to arrive
at a common goal.
* Solid and robust yet lightweight, therefore carbonfibre casing.
* Perfect match with the 13B bolt pattern, no additional backing
plate.
* Built in front Lord motor mounts.
* Standard, fixed dimension from engine plate to prop flange (say,
14"?)
* Zero vertical offset, therefore planetary gear set.
* Wide range of input power therefore set design load limit to upper
end,
say 1,000 hp, and exchange gearset as needed to reduce weight as less
power is required. * Moderate range of gear ratios available,
perhaps between 2.5:1 and 3.5:1
* Gearsets mass produced and readily available in variety of ratios,
and variety of load rating, probably automotive source.
* Oil lubrication from engine oil to allow for existing cooling
* Hydraulic or electric governor option.
* Variety of prop flange bolt patterns available
* Direction of rotation option available
* Lightweight flywheel with built-in torsional dampening.
* Standard provision for electric starter
My goal here is to produce and make available a lightweight PSRU
that could be
ordered with the customer options as above, and the box would bolt
on the
engine right out of the crate. All specs would be known well in
advance and
firewall-forward engineering issues would be minimized. Cost and
weight would
vary only with the size of the gearset. The same case would be used
for all
models, even though it's designed for max loads. Therefore, a PSRU
for a 200
hp would be lighter than for a 1,000 hp only because the gearset is
lighter.
Everything else would be identical/interchangeable.
Why would I invest in such a project? Three main reasons: To
advance the
rotary aeroengine, to have available a well engineered, reliable
PSRU, and to
defer the costs associated with what I'm probably going to do anyway.
Any suggestions to add to this wishlist? Any takers? Any pre-
orders? The
first prototype will be the expensive one on my nickel, but
subsequent units
should be under $5,000 if design is successful and marketable.
Greg Fleming
London, Ontario, Canada
There are a few things that are very difficult to do.
For example one is changing rotation directions and getting
reduction ratios over about 3:1 with a planetary gear set.
Don't forget low cost is the primary driver for adopting the
rotary in the experimental market. Right now the price point is $3000.
This has been and will be in the foreseeable future. That implies
an off the shelf gear set like the Ford. That would also preclude
carbon fiber.
A high priority would be a prop governor drive for a constant
speed prop. There are only two standard prop flanges needed.
One for wood prop and one for CS props.
Paul Lamar
Greg, there are further complications blocking the universal firewall
forward package. These arise from the fact that the various airframes
require different plate to firewall distances, have different attach
points on the firewall, have more or less space inside the cowl which
complicates the cooling design and so on. Even the length of the S-
beams varies with each application. Regards, Jerry
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