From: Doug Jones (djones@xcor.com)
Date: Tue Mar 26 2002 - 22:15:00 MST
spike66new wrote:
>
> There is a mind blowing article in the March 2002 issue of Smithsonian
> Air and Space. Marti Sarigul-Klijn describes a harrowing Roton test
> flight. His description of the last days of Rotary Rocket Inc was worth
> the cover price in itself. It will be interesting to hear Doug Jones' take
> on this. Doug, I will send you the issue thru the snail mail if you post
> me your @. spike
I've seen the article- I knew at the time that the ATV was a hairy
vehicle, and that it had some really ugly vibration problems, but the
bit about the catalyst tank shaking loose was news to me. (I and all
the rest of the propulsion team had been laid off in June 1999.) I'm
not sure that the vibration was due to the energetic rotor vortex cores
hitting the airframe; other possibilities were asymmetrical thrust
output from the tip thrusters (there was no flow spreader at the rotor
hub), or the peroxide free surfaces in the lines in the rotors could
have been at different heights, unbalancing the rotors.
I watched all the flights, and what really scared me about that last one
was the severe uncommanded left yaw that occurred right after liftoff
and pitchover to accelerate down the runway. I think it may have been
caused by the increase in bearing drag when the pilot pulled
collective. It seemed to take forever for the yaw thrusters to counter
it and get the crew facing forward again. I still admire them for
successfully flying a very difficult vehicle.
I _don't_ think the vibration was due to the lead-lag hinges; footage
from the whirlstand rotor cam showed that the thrust pulled the blades
only slightly forward, and they were far from their stops.
The autorotating Roton would have been a pretty poor glider; the best
L/D speed was predicted to be about 60 kts at about 1:1- 3500 fpm down
and not much more forward, and the glide range from 30,000 would have
been only a few miles. Winged vehicles look mighty good in comparison
these days...
Next flight of the EZ-Rocket should be next week, we may have Dick try
another touch-and-go.
-- Doug Jones, Rocket Plumber
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