Buly,
Congratulations on the installation. It looks really good! Since you
are obviously very close to an adequate configuration, I would suggest
tweaking what you have, rather than adding another system. First, I
would make a little pitot tube and affix it to the entrance of the
ejector so you can get a relative measure of the velocity of the air
entering the ejector. This way you can try things quickly and
determine
whether the results are good or bad. No need to fly the plane, since
the issue is with cooling on the ground at engine idle. By the way,
glass eye droppers make great little "laboratory" pitot tubes. Or if
you have an RC car hobby shop nearby, get a piece of brass tubing and
some silicone fuel line to connect it to a manometer. The pressure
differentials here will be very small. So, to see the relative
differences in pressure you will need to make a water manometer
with the
low pressure side slanted at maybe a 70 to 80 degree angle. Clear
vinyl
tubing works great for this.
Thanks for the ideas Aubrey, but right now my plate is full :). Also
the space between the exhaust and prop is minimal.
I don't have the distance to play with like in the laboratory.
Now, I would use cardboard and duct tape to try some changes to the
ejector tube. The angled end probably degrades the ejector
performance, try squaring that off. From the photos that Paul
attached,
it is not clear how far into the ejector tube the engine exhaust pipes
are located. Try adding an inch or two to the ejector tube length at
the rear. The exhaust gasses need to be in the ejector tube for a
distance of one or two ejector tube diameters to get the best effect.
If these ideas don't give more apparent flow, then I would go by a
gutter shop and get a few feet of unformed aluminum and pop rivet
together some trial ejector tubes of different diameters. If I were
making a new trial ejector tube my first try would be this one; I
would keep the same entrance area, make it as long as possible,
make it
oval similar to the exhaust pipe, and give it a taper of about 7% from
front to rear.
Also make sure the ejector tube is sealed to the cowl.
It is great to see a rotary installation so well done. I know it is
probably not feasible for you to have the plane at Sun N Fun.
Could we
make a poster board and show off photos of your installation at the
rotary tent?
Aubrey Thompson
I would be happy to bring the plane to a event focused on
experimental planes or rotary engines.
But there is no way I'm to bring it to lakeland and wary for a week
that some idiot will damage it trying to amuse himself or his brats,
while I'm not looking. I have lost interest in S&F circus years ago.
Me and the wife travel to KY every year for the canard fly-in and
Tracy's
Rotary Roundup. This year I may drive for a day?
I have no objections of any photos of the installations being
displayed. I can send you some if you like.
Buly
Here is one, parked at Okeechobee airport last sunday:
Come on Buly is not all that bad. I have never seen or heard of a
rotary powered airplane damaged at Sun n Fun and I have been going
for ten years. You are out on the line with the other rotaries
and there is always some one around until they close the tie down
area at 2 PM for the air show. Tracy and Laura spend the day out there
or some other pilots of the rotary powered air planes. I am out there
for awhile but spend most of my time in the rotary engine workshop
tent. During the week you rarely see children anyway. If you
want to leave early Saturday morning or Friday night that would be
alright with most people as most leave early Sunday morning anyway.
Here is another possibility. Fly into one of the surrounding airports
like Bartow and we can buzz down and take a look.
Paul Lamar
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