Paul,
I am a mechanical engineer that owns a cnc machine shop in northern
California. As a new pilot, and a past rotary engine builder, I am in
the progress of developing an aircraft specific rotary using some off
the shelf Mazda parts and many custom parts. The current goal is to
offer these parts to the experimental aircraft market within the next 2
years. I am estimating around 1 year of design and prototyping and a
year of endurance testing before release of any products.
The real motivation is I will be starting a Velocity XL kit this fall
(after the Reno Air Races), when my time will become a little easier. I
am the team engineer and fabricator for Team Steadfast owned by Will
Whiteside. We use a 2005 Romanian built Yak 3U with a P/W R2000 radial
engine. You can check out the web site at teamsteadfast.com.
Please add me to your newsletter mailing list. Your web site is great!
I would like to use you as a sounding board to possibly review some of
the parts we will me making on the basis you keep them confidential
until we are ready to release the parts to the market. My plan would be
to resale the parts through the existing guys building rotary aircraft
engines, as I really don?t have any interest in being an engine
assembler (besides my own)!
Thanks,
Larry Childs
Designit Prototype
5935 Labath Ave
Rohnert Park, CA 94928
Cell 707-753-0702
I'll be glad to help anyway I can.
You are also just the person I have been looking for.
I have been farming prototype work out to various local NC machine shops
but I would rather keep it in the Wankel rotary community. I pay for it
out of my own pocket no problem.
I am trying to design a slide throttle low pressure fuel injection
based on the Ellison carb. We have a guy already set up to make
the slide throttle itself. I am building up a p-port RX8 engine
and we will initially run it on the Mazdatrix engine dyno with a Weber
carb
to get a base line. Once that happens. I will try some of these other
ideas for
low pressure mechanical fuel injection. The traditional EFI is overkill
and too
expensive. Most people are attracted to the rotary for cost reasons.
Also it relies on a functioning electrical system which does not always
function.
This design steals ideas from Ellison and Mikuni.
The fuel metering is done with a bunch of small holes
drilled into a brass tube that stays in the air passage
all the time similar to the Ellison. As the slide opens it exposes
more
and more small holes in the brass tube increasing the fuel flow.
The brass tube is attached to the spacer. The fuel comes in through
the
spacer and down the column to the brass tube. The brass tube
fits in holes in the center parts of the slide. The fuel is
sucked out of the side of the tube by the Coanda effect.
Ellison claims excellent atomization.
It uses a tried and true method of metering fuel. There are
hundreds of Ellisons out there on all sorts of airplanes. The
mixture is
also leaned with the external fuel pressure regulator. The Ellison of
course has a built in fixed fuel pressure regulator.
I calculated the air opening area of the slide in .2 inch travel
increments. I then attempted to match the fuel flow to the slide
opening area.
Roughly speaking it takes 27 .013" dia. holes variably spaced
along the tube. Each hole passes enough fuel for 4.45 HP at 2 psi so
27 holes is 120 HP per runner. 240 HP for the p-port engine.
As Ben Ellison says this causes a stepped ramp digital supply of
fuel.
In other words the engine goes from rich to lean and back to rich as
the slide moves. The problem is severe in the first one third
travel of the slide throttle. Ellison largely got around this by
using much smaller holes and many more of them. My guess by looking
at them is
they can be as small as .1 mm or around 6 thousands of an inch. He
probably has
close to 100 holes in his tubes.
More, much smaller holes, soon becomes a problem in a single row as
the holes get too close together. Two or more staggered rows are
used in the
Ellison. The first 3rd are a single row. The next third is a
staggered
double row and the last third is a staggered triple row. None of this
is shown
on any Ellison websites. Of course this further increases the cost.
I talked to a friend of mine that owns an NC shop here in Santa
Paula that has experience drilling small holes. He says there must
be a close
fitting brass rod in the brass tube or drill breakage occurs
frequently. At
$45 a crack you don't want this to happen. Then you have the problem
of pressing
the sacrificial brass rod out of the nine inch long 1/8 inch
diameter
tube.
Not an easy thing to do. That too requires special tooling that
supports
the outside of the tube. Perhaps this can be done better with a
laser.
I have yet to investigate the laser option. I am sure this outfit
can do
the job. I'll know more about the cost on Monday.
http://www.calasers.com/gallery.html
Two Ellisons would work fine but at $850 each they are too expensive
for most rotary guys.
Paul Lamar ...No rotor no motor.
Wahooo,. another Velocity builder using a Rotary. I have the Velocity SE
down here in Houston and we had our first engine start on May 30th, 2007.
However, I just sent my ECU and EM back to Tracy Crook to be upgraded with
the engine diagnostice funtions to make troubleshooting and tweeking easier.
So, while I am going crazy waiting for Tracy to return my stuff, I hope to
start making the bird more....uh, well, you know, FLYABLE <g>.
You should find Velocity, Inc a great company to work with. Should you
have any questions feel free to ask 'em....or me (If I know, I will gladly
share). Also, be sure to subscribe to the Reflector, the builder only email
list for the Velocity. Velocity, Inc should be able to hook you up with the
proper info. Also, you may be albe to get more info at
http://www.tvbf.org
(The Velocity Builders Forum).
Good luck.
All the best,
Chris Barber
www.LoneStarVelocity.com
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