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Steve Baughman
Web Updated Apr 7
© 1999
All Rights Reserved.
XRV ROCKET PROJECT BREAKS ONE MILE BARRIER
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Steve Baughman poses with the XRV Mk. IV at rollout. Photo by Jim Baughman |
MK IV SYSTEM UPGRADES
The key to success at this altitude hinged on recent
upgrades which turned the XRV Mk III into the Mk IV. The most significant of
these was the addition of the FBFS 3-channel pyro ignition module (PIM), which
was linked to the XRV's telemetry microcontroller unit (TMU). Under direction of
the TMU, the new PIM capability employs optical switching circuitry to fire
explosive charges which are used to deploy a small drogue parachute at flight
apogee and a large main parachute at a ground proximity of 500 feet. Dual
parachute deployment enables the rocket to descend safely from maximum altitude
with a minimum of lateral drift, which is critical in avoiding loss of the
vehicle during high flights.
NTHP FLIGHT PREP - 3:30 pm, Saturday February 13, 1999
The vehicle was
disassembled and explosive charges were constructed and installed. Motor assembly
followed, and after installation of the motor retention system, the TMU and PIM
were powered up to idle while the final vehicle assembly was completed in the
launch support vehicle (LSV). Final loaded weight (i.e. stage weight) was 12.75
pounds. A flight card was prepared and the rocket was carried to the NTHP launch
safety officer (LSO) for check-in. The LSO approved the flight and we were handed
off to the pad manager (PM), who inspected the flight card and directed us to pad
number 4 west. The XRV was loaded onto pad 4 in a vertical configuration, the
motor ignition system was armed, and the TMU was switched into 'armed' mode. We
then backed away from the pad and waited for the launch control officer (LCO) to
initiate the launch sequence.
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The XRV Mk IV hit a speed of 415 mph in only 2.7 seconds to reach 6060 feet. Photo by Steve Baughman |
The Aerotech RMS-K550W burn sequence was electronically initiated using a pyrogen-based electric match wrapped with unsheathed Thermalite detonation cord. The composite solid rocket motor, which burns a mixture of hydroxyl-terminated poly-butadene (HTPB) for fuel and ammonium perchlorate (AP) as oxidizer, lit instantly to full power delivering 190 pounds of thrust, which lifted the rocket spectacularly off the pad. The force of launch was monitored via a Motorola PMMA2000W accelerometer in the TMU, and upon launch detection the TMU started the flight timer and initiated the high-res flight mode, recording 8-bit pressure and acceleration data to the on-board EEPROM at a sampling rate of 20 Hz. Maximum acceleration of 10.7 g's was recorded at T+ 0.35s, and a maximum velocity of 607 fps (415 mph; mach 0.53) was reached at T+ 2.70s at an altitude of 1032 ft. Motor burnout occurred at T+ 3.10s, and aerodynamic drag began to decelerate the airframe with a force of up to -1.9 g's during unpowered ascent (coasting), which lasted 15.20 seconds. At T+ 18.30s, flight apogee was detected by the TMU through a Motorola MPX4100A pressure sensor at the maximum altitude of 6060 ft. (Maximum altitude figures are confirmed by comparing pressure data to integrated acceleration data, which on this flight reported a 99.2% agreement between these two independent altitude measuring systems.)
FLIGHT DETAILS - DESCENT PHASE
Upon detection of flight apogee, the TMU activated
PIM channel 1, igniting a 1.5 gram explosive charge in order to deploy the fully
reefed 18" drogue parachute. Deployment was confirmed by the TMU drogue chute
failsafe sensor 0.05 seconds later at T+ 18.35s, and the vehicle then began a
93.15 second freefall drogue descent at an average speed of 59.6 fps (41 mph). At
T+ 20.00s, the TMU switched into a low-res flight mode with a slower data
recording rate of 2 Hz, in order to conserve EEPROM storage space during descent.
Drogue freefall continued until the preset 500 foot ground proximity level was
detected by the TMU pressure sensor at T+ 111.50s. In response the TMU activated
PIM channel 2, igniting another explosive charge to deploy the 52" main
parachute. Deployment was confirmed by the TMU main chute failsafe sensor 0.5
seconds later at T+ 112.00s. Descent was slowed by the main parachute to 28.6 fps
(19 mph), and at T+ 126.00s the rocket gently touched down approximately 2000
feet downrange of the launch pad. The TMU continued recording data for another
203.50 seconds, and at T+ 329.50s the EEPROM reached maximum capacity, forcing
the TMU into 'landed' mode. Upon retrieval and return to the LSV, all flight data
was dumped via RS-232 to a laptop terminal for storage and analysis.
Telemetry:
Flight 15
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The XTRM seen in a recent spy photo. Photo by unnamed covert operative |
This flight demonstrates the steady advancement of the XRV development program, which was originally conceived in July of 1998 with the goals of reaching Tripoli Rocketry Association level 1 and 2 certification, flying over a mile high, and reaching supersonic velocity. Supersonics are the only original goal left for the XRV program which remain unachieved. To help accomplish this final goal, an XRV Mk V booster is being developed which will provide three times the power of the current booster through the use of larger 75mm diameter motors. Supersonic flight experience will be crucial in the successful completion of Baughman's planned follow-on vehicle, the XTRM. Details of this project continue to be closely held, but sources indicate that the XTRM project is a planned multi-stage-capable carbon composite airframe designed to attain TRA level III certification using the upper stage only.
Fly By Fire Systems (FBFS) is an Austin, Texas-based company specializing in the design and integration of telemetric digital flight control systems for use in high altitude research applications. For more information contact Steve Baughman, President - sbaughmn@swbell.net
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