Paul,
Yes, it's out in paperback on Amazon.com.
I haven't found a professional narrator I like yet though. The book
is very movie-like with many characters who appear in four time
periods, ancient to present. Interspersed within the story are some
flying scenes you would enjoy. The book looks at time travel from
the viewpoint of both metaphysics as well as astrophysics. Time is a
place is the underlying precept. Could be just another hare brained
idea though:
Rotary progress:
I'm making up the Aluminum housing and PSRU mounting plate out of
2024 Al. now. I found that I will have to have to make a new sun
gear combination, splined shaft, to get a robust connection to the
drive spline. I'm still not completely convinced on the method for a
torsional resonator absorber. Mistral used springs and Tracy uses
rubber. I'll have to make a choice, run it and then see what
happens. I worry about the increase cycle rate and durability that
springs would encounter. Having the prop spinning a the same rpm as
the rotor could potentially be a good or bad thing. I'm beginning
to understand there is no one-off solution. Different propeller
weights and materials will resonate at different frequencies.
Cheers
Doug
Springs give no damping.
Experience with two entirely different rotary engine and coupler
designs and with different displacements, both resonating just below
2000 RPM more or less, acting identically, I conclude there is no
solution. Idle the engine below 2000 RPM and forget about it. After
all the prop is turning at 700.
I gave the book to Robin.
Paul Lamar
I believe there are some clutch hub springs damped with rubber for heavy
trucks. How about injecting some silicone in the springs for damping?
Dale Davies
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Trucks have springs in the clutch for taking off initially. After I let
the clutch out and get moving, I dont use it again until I need to stop. If
you have ever driven one of these things, you will notice that if you are
not soft and gentle with the application of the clutch (letting off the
pedal) the thing starts to buck like a bronco. The springs tend to add
energy to the system, which leads up to boing boing boing and an
embarassing start to the trip. I would think that springs in the backing
plate could also add energy to the system and ultimately cause a
catastrophic failure. Imagine sitting on the taxiway at idle waiting on
your turn to go. Each firing of the rotor causes an impulse that is
transferred to the springs and then ultimately to the prop. Your engine and
prop are happy, then along comes a brisk gust from behind (you are on the
taxiway pointed downwind). This gust will load the prop and compress the
springs. At the same time the rotor impulse subsides, the gust stops, and
the energy built up in the spring gets transferred to the prop, only this
time the prop tries to outrun the engine. Now here comes another rotor
impulse, the engine quickly catches and passes the prop since it has
virtually no load at the moment, and the cycle repeats. I can see a
scenario like aileron flutter- a few short seconds and boom its over.
The closest thing I can think of to the problem that is being discussed is
a tractor and bushhog. At idle with the PTO in gear there is considerable
back and forth when each cylinder fires. Rev up the tractor and it goes
away. We solve this by using an over-run clutch. This little device lets
the bush hog outrun the tractor and then the tractor gets to catch up. The
engineering is sound, but for us I would be concerned with the prop
overspeeding during a descent. Another alternative would be a constant
pitch prop- at idle the prop could be set almost feathered for the most
drag. At run up or takeoff, reduce to fine pitch. Lots of performance
planes go to feather at loss of oil pressure, maybe someone with a CS prop
could test this theory?
I don't think we need to dampen the system as much as just keep the prop
behind the engine- i.e. under load.
Another possible solution would be a belt drive with what would be a
tensioner device like on your car. This little wheel keeps the belt tight,
but also takes the shocks out of the system. For this reason I kind of like
the Ross type of PSRU with the big belt. I have bulldozers with rubber
tracks, so the technology is here to transfer the power from the engine to
the prop effectively and reliably with a belt. If you look at many of the
small helicopters, they have belt drives from the engine to the gear box.
I dont think the Ross is the belt driven unit, but I am sure you guys are
familiar with what I am referring to.
Kevin Alderman
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