[AR] Re: Dynamic stability in supersonic rockets
- From: Mike Caplinger <mc@xxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Tue, 16 Nov 2021 17:41:36 -0800
On 11/16/21 3:26 PM, William Claybaugh wrote:
Experience differs: when building machines that are going to go from
zero to 2000 mph in six or eight seconds it has been my experience
that any piece part that is not absolutely hell for stout will fail.
My experience in this area is trying to exceed 2000 mph with smallish
J-L commercial rocket motors like the Cesaroni J530 or K1440, so there's
a premium on low dry mass. Maybe I simply tried to over-optimize, but I
had several flights where there was no obvious coning, the fins stayed
on, but the rocket broke between the motor and the nose cone joint
despite the use of what seemed like fairly robust materials (phenolic
laminated with fiberglass or carbon fiber, "Blue Tube" fish paper, etc.)
In these flights the characteristic was a single sharp turn right around
max Q, not wiggles. At least as far as I could tell; these flights are
hard to follow by eye or video since the acceleration is typically
50-60g and the motors only burn for 2-3 seconds at most.
I eventually managed to reach about 1960 mph on a Cesaroni L1030 -- that
one was thin-wall filament-wound fiberglass and just a little too heavy
to meet my goal.
See "Speed Limits: Sport Rockets Beyond 2,000 MPH", Sport Rocketry 57,3
(May/June 2015) for details.
BTW, this is not a terribly noteworthy accomplishment, many HPR fliers
have gone far faster than this, but I'm not sure there's a lot of
experience in this low-impulse corner.
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