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"Garth R." Flight Systems Profile
By: Mark Havener, NAR #76868
The next High Power Rocket to be produced by Team Havener will be
named the "Garth R." in memory of my father who passed in 2001. I
was calling it "Redundant Redundant" with the basic design of using
multiple recovery systems to insure repeated safe recoveries.
The predecessor to the "Garth R." was the Buckaroo 2, a Binder
Design Sentinel, modified for a removable electronics bay and dual
deployment. The first two flights under I161 power saw the B2
constructed in stock, with a kludge for an AltAcc 2A flight
computer. The first flight was for my Level 1 certification. The
electronics was along for flight data recording only. The rocket was
successfully recovered via motor ejection. The second flight was
with the electronics packing in full control of recovery in dual
deployment mode. This flight was also 100% successful.
The third flight was very lucky. In an imitation of the prior
flight, the rocket was sent aloft with the electronics in control of
the dual deployment. The difference was this was my Level 2
certification flight, using a J350. The B2 experienced an in-flight
electronics failure. Fortunately, the motor ejected the streamer for
a hard, but survivable landing. Post flight analysis determined the
probable cause was a large capacitor had broken one lead off the
board during the 33G liftoff. The AltAcc was returned to the
manufacturer for repair. The Buckaroo 2 was lost on its' fourth
flight as a result of the failure of both electronic and motor
ejection systems. When both recovery systems failed, the rocket came
in ballistic, resulting in a total loss of the airframe and
electronics. The motor casing was recovered with only cosmetic
damage.
The Garth R. will be carefully designed, utilizing the latest
developments in high power rocketry technological advances. Each of
the individual particulars will be discussed individually in detail
by later in this paper.
Physically, the Garth R. will be similar to the Buckaroo 2, those
being a 4" diameter airframe and a body length of 122.25" from tip
to tail. A Binder Design Raptor is the airframe, with a 4" body tube
extension to provide a payload bay. The airframe will be able to
handle AeroTech RMS up to 54mm, giving a maximum of 2400 N-seconds
of thrust.
Specific technologies include:
MULTIPLE RECOVERY TECHNOLOGIES: The Buckaroo 2 had a
single level of recovery system redundancy, a motor backup to an
accelerometer/altimeter electronic deployment. The Garth R. will use
three different recovery systems. Primary recovery will fall on the
AltAcc 2a flight computer. The AltAcc uses an accelerometer to
determine apogee, and a barometric sensor to pop the main parachute
at 500 feet. Secondaty recovery will be a MissileWorks PET2
timer. This timer will be set to deploy both Drogue and Main
systems. The tertiary recovery system will be the motor backup,
which will at least deploy the Drogue if all of the higher level
systems have failed.
ELECTRONICS BAY: The Buckaroo 2 had an electronics bay
that doubled as the tube coupler between the Booster and Payload
sections of the rocket. It was secured to the Payload section of the
rocket by eight through-the-wall screws. The Garth R.'s bay will be
a BT extention designed by Binder Design. The body tube extention is
used to provide easy external access to key switches that will arm
the electronics. Considering the level of redundancy that exists
with the electronics, two separate charges for each the Drogue and
Main deployments will be required. The AltAcc and the backup timer
will have their own ejection charges.
IMPROVED PROCEDURES: The failure of the Buckaroo 2 cannot
be blamed on either the preparation or pre-flight operational
procedures. The procedures were also not at fault due to failing to
detect problems in the electronics. The operator correctly followed
all instructions as to the preparation of the rocket, electronics
and motor assembly.
But even though all procedures were followed and upon review
found to be correct and complete, this does not mean the procedures
do not need to be reevaluated during the constructions and
outfitting of the Garth R.
TESTED ELECTRIC MATCHES: Broken Christmas lights will be
used as e-matches for all electronic deployment. If these do not
work, other brands will be tested. In any case, every electronic
package will be tested 2-4 times with the electric matches under
test before any brand will be accepted and used in a live launch.
TESTING PROCEDURES: The Buckaroo 2's on-board electronics
had no easy way to perform an operations test on the ground. During
arming on the pad, the electronics did properly sense both of the
electric matches. Procedures will be devised and extra electric
matches produced so each piece of electronics will be tested live
(without BP) before installation into the airframe. The goal is to
provide a reliability index in excess of 95% before each launch. The
extra matches needed to systems test and ground test will actually
increase reliability in individual matches due to bigger runs and
quality control.
The Garth R. will be a very busy airframe with a big reputation
to live up to, before it even gets off the paper. Because of the
limited monthly budget, complex design and other issues that need to
be solved in a systematic manner, construction of the actual rocket
will actually be one of the last things to be done. Countdown has
begun, with a lift-off time scheduled to be 12:00 Noon, 5/15/05.
Successfully Recovered!
Post Flight Analysis:
The Pratt Hobbies WEC-5 ejection charges did not work to separate
the booster and electronics bay, but the motor ejection saved the
day. The Pratt Hobbies VCEC ejection charges did work, ejecting the
parachute.
Damage was minor and confined to the bottom edge of the
electronics bay, due to the fact that I didn't tighten the nuts
holding the bay together enough. |
