Paul, what happened to the little prop dyno that you had mounted on
a trailer? I have been waiting for you to use it, to see what
changes if any you would recommend, before building one for
myself. Could you put Mark's engine on it? BTW, I have no need
for the trailer version. Mine could be solid mounted bolted down to
the shop floor. Jerry
The house project is eating all my spare time.
Extend the bottom legs further up under the engine
to balance it better. You don't need the static thrust
measuring capability as it can be misleading.
Rather than the bathroom scale there are other ways
of measuring the torque. A calibrated garage door
spring is one of them. Use a shock absorber to damp
out any oscillation.
Let me know if you need any advice.
Paul Lamar ...No rotor no motor.
Use a hydraulic cylinder with a gage and calculate the psi
into lbs pull.
Ken
Yes that will work too. Lets see what McMaster Carr has in cheap
cylinders. You can get up to a four inch stroke for the same
$213.
Pressure gages run another $10 to $100 depending on accuracy
and diameter.
Its a bit more money than the spring and a ruler but it
will probably be more practical to read.
Paul Lamar ...No rotor no motor.
For this use I think you could use the cheep Bimba type disposable
air cylinders which will also work with hydraulic fluid.
Ken
Ken
I believe you have a lot of experience with Warp Drive propellers. I am
thinking of making a portable dyno room with a steel square tube frame
that
is experimentally 6' high, 6' wide and 8' long. It would be totally
skinned in plywood on the outside for strength, and thin sheet metal
on the
inside with fiberglass sound insulation in between with wired safety
windows
on both sides. Actually the room splits apart and allows one to pull
the
engine mount and frame on wheels on out the back. Imagine the back and
bottom side mounted on a L-shape frame on wheels while the rest of the
'room' remains on four anchor bolted legs and you'll get the idea. Air
intake is through the front duct in front of the prop and exhaust
would be
though the back outlets around the peripheral of the engine and
firewall.
Obviously the fire wall will need some frame members ( X shape?) to
support
it. They should be faired where they enter the air stream. Interior
walls
of the chamber would have to be optimized to increase the speed but
The purpose is to size the adjustable outlets to get an airflow of at
least 100 mph through the enclosure. Perhaps I could test cooling duct
design at the same time as I'm running the engine.
Seeing those props on an air boat gave me the idea.
Assume I found a inexpensive way to make a CS electrically driven
Warp drive that is good enough for test purposes only. Would six
blades be
enough to absorb the power of a 300+ engine? I heard someone say 50
hp a
blade but their website is not clear to me.
Doug Fir
I like the rad test idea. Makes making the dyno more worth
while. You simultaneously have an unlimited source of heated
water and a significant air flow. If you make a convergent
duct for the prop you could get much more than a 100 MPH
through your cooling tunnel. Very good idea Doug.
Paul Lamar
Doug,
This is a pretty cool idea. I would adopt a more "roundish" shape
because it would be easier to brace against pressure differences. I
don't know what is available to you, cheaply, there. Gypsum drywall
sheets would be cheap material here. It has good vibration damping
properties and could be layered with some kind of woven reinforcement
between layers. An octagonal tube made up on an external wood frame
with two layers of gypsum board, "chicken wire" screen between, and
glued together with construction adhesive would be cheap and tough. Of
course it would be heavy and NOT waterproof. We import a lot of Luan
Mahogany plywood that is probably manufactured somewhere near Japan.
Something like that may be a better choice for you.
Aubrey
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