Mark X
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Design overview:
The rocket design allows the rocket to utilize many different
motors ranging from high impulse K motors through the
largest 98mm motors available (typically, N motors). The use of a
K-class motor provides a low and spectacular flight while
larger motors can push the Mark X to
altitudes exceeding 10,000 feet. This gives the
rocket great versatility.
Airframe Design:
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The rocket has a diameter and length of
approximately 7.5" and 144", respectively. The
propulsion section has space for motor casings with
a maximum length of 53 inches and features a
removable coupler. Eight 8-32 machine screws
are used to hold the four motor mount centering
rings to the airframe as well as 30-minute epoxy.
Wooden support rods also run between each of the
centering rings to spread out forces encountered
during powered flight. A 98mm AeroPack retainer and a 75mm AeroPack
adapter kit, allowing the use of 75mm motors, are
used to ensure positive motor retention for 98 and
75mm motors. The fins have plywood
supports and balsa skins with the void filled with a
light weight foam. Each fin is also reinforced
with a layer of 6 oz. automotive fiberglass. |
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Mechanical Drawings:
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Recovery
System Design:Dual-recovery of the Mark X
is controlled by two pieces of flight avionics for
redundancy . The G-Wiz Partners MC 2.0 flight
computer is the primary unit and fires the primary
drogue parachute separation charge (DPSC) at apogee and
the primary main parachute separation charge (MPSC) at
800' AGL. A PerfectFlite miniAlt/WD serves
as the back-up unit and fires the back-up DPSC 4
seconds after apogee (using the mach delay), and the
back-up MPSC at 500' AGL. The DPSC are loaded with
2.4 grams of Pyrodex and the MPSC are loaded with 4.7
grams of Pyrodex. Each section of the recovery
airframes are held in place during flight by 4 sheer
pins, #2-56 nylon screws. Separation charge sizing
calculations appear at the end of this section (page 3).
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Avionics Discussion:
There are two avionics units controlling deployment of
the recovery devices for the Mark X Rocket.
Both are automated units armed only after the rocket has
been lifted to vertical on the launch pad. Power
on/off to each unit is controlled by two 2-position
rotary voltage selector switches available from Allied
Electronics, part #287-1022. Both stages of
deployment utilize two separation charges with each
charge being wired to only one flight computer. In order
to get accurate barometric sensor readings to deploy the
main parachute, 8 evenly spaced 1/4" static port holes
ensure accurate sensor readings. Calculations to
determine port hole sizing appear at the end of this
section (page 3). Avionics
components: |
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GWiz MC2:
The GWiz MC2 flight computer functions as the main deployment controller for
the Mark X. The computer itself is capable of controlling up to 4 phases of flight and can be
powered by either one or two batteries. The MC2.0
determines apogee with an accelerometer and then uses a
barometer for low altitude deployment. There are four pyrotechnic channels on the unit.
Channel one can be set to fire on liftoff detection,
motor burnout, or a set time after either previous
phases of flight. The second pyrotechnic channel
deploys a
recovery device at apogee, and the third channel is used
to deploy a recovery device at either a fixed time after
apogee or at a fixed altitude. Pyrotechnic channel
four is programmable by the user.
As stated above, the GWiz MC2 has two possible power
configurations. The first one, and less reliable,
is a
single battery configuration in which both the computer and pyrotechnic
channels are powered by one battery. In this
configuration, it is possible for the flight computer to
loose power as each pyrotechnic channel fires. The
second configuration, used on the Mark X, uses separate
batteries to power the flight computer and pyro outputs.
This configuration is also the most reliable of the two.
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PerfectFlite miniAlt/WD:
The PerfectFlite miniAlt/WD is a simple dual deployment
altimeter which uses a barometric sensor to detect apogee
and altitude for triggering of the
deployment events. A mach delay is included in the
design and can be set by setting the dipswitches in the
proper configuration. |
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Avionics Drawings:
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Recovery Harness
Design:Each of the two recovery harnesses
are constructed of 30'X1" mil-spec
tubular nylon webbing with a tensile strength of
4,000 lb. 1" metal D-rings are secured to all
attachment points via sewn loops of nylon webbing.
The parachute attachment points are located 10' from
the front of each harness, which attaches to the
separation bulkheads.
Harness Design Drawing: |
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Parachutes:
The drogue parachute is a 66" de-milled parachute
and the main parachute is a 17' de-milled parachute.
At apogee, the 66" drogue parachute deploys and
provides an estimated descent rate of 50 Ft./sec.
After main parachute deployment, the estimated
descent rate of 15 Ft./sec. The aforementioned
descent rates assume the rocket weighs approximately
44 lb. after motor burnout. The descent rate
calculations are presented at the end of this
section (page 3).
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