Claimed to be useful gyro building blocks (see discussion below)=20

        http://www.spp.co.jp/sssj/sirikon-e.html

Certainly look "fun" for experimental use.

But also see John Carmack's comments at end - and he has hands on =
practical experience (including manned rocket only supported flight, *so =
far* for less time than the Wright Brothers first flight).=20

            RM

_____________________


----- Original Message -----=20
From: Scott Bowers=20
To: AROCKET@HOME.EASE.LSOFT.COM=20
Sent: Sunday, November 17, 2002 2:45 PM
Subject: Re: [AR] Gyro Hunters


I am not really the electronics guru. I have a friend in the aerospace =
industry who pointed them out to me. The price was approx. 37.00 dollars =
each, and you need three. John made a gyro unit for his rc helicopter. =
He designed the board and firmware himself. He put the thing upside down =
and locks it in and it stays there, pretty impressive.=20

He will eventually be manufacturing some. He said they have a sample =
rate of about 90 times per second, and should be fast enough with the =
right servos to steer a rocket.

We worked out an idea for X, Y, and rotational axis control using only =
two servos and a link similar to what they use in tailless planes.

Been one of my goals to do this, may actually get around to it someday.

Scott
  ----- Original Message -----=20
  From: Brian Feeney=20
  To: Scott Bowers ; AROCKET@HOME.EASE.LSOFT.COM=20
  Sent: Saturday, November 16, 2002 5:20 PM
  Subject: RE: [AR] Gyro Hunters


  In a write up on their site they compare the different technologies =
employed in gyros. They claim to have solved the problem of external =
vibration normally causing the Vibration style to be ineffective. Have =
you flown this and or know of its use on rockets aka was it really =
effective in the context of the vibration from the rocket. How much were =
you paying for them?=20
  Cheers,
  Brian
  The da Vinci Project

  bfeeney@davinciproject.com
  http://www.davinciproject.com=20

    -----Original Message-----
    Scott Bowers  wrote=20
    Sent: Saturday, November 16, 2002 7:47 PM


    I would use this one. Smal, fast, And cheap.

    http://www.spp.co.jp/sssj/sirikon-e.html


    Scott T Bowers

    ____________

    At 07:45 PM 11/16/2002 -0500, you wrote:

      I've seen them fly and they are an interesting toy. There are =
several problems with the simple stability platform. They use solid =
state rate gyros and no accelerometers. The Dragonflyer does not hover =
without a lot of manual control. It rocks from side to side in flight =
due to the low resolution of the rate gyros. You must constantly correct =
for drift. If they added a three axis accelerometer then it would be a =
stable platform that would hover. It would be questionable as an active =
guidance system for a rocket.=20

      John Krell

    A three axis accelerometer doesn't have anything to do with attitude =
stability, and can't help sub-par gyros.  Accelerometers are only needed =
(in conjunction with the gyros) for position, and it takes really =
surprisingly good gyros and accelerometers to make a 6DOF inertial =
integration not fly out of the room in seconds.

    2D inertial with a single gyro and dual axis accelerometer is not =
that bad for human-scale movement, but as soon as you add the third =
dimension with the constant 1G gravity vector, the integration gets ugly =
real fast.  A hovering vehicle done strictly with integrated inertial =
sensors (no absolute sensors like GPS, horizon, sun , electrostatic, =
magnetometers, barometeric, laser, etc) needs a much better set of =
sensors than the $9,000 Crossbow IMU we use.  After a 15 second flight, =
the inertial position is already several feet off, and diverging with a =
velocity.  It is good enough for things like apogee detection, but =
definitely not for the "hover steadily in front of me" maneuver.

    John Carmack

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