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SS1 Reduced Scale Test Vehicle: Flight 2
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As a reminder to of the lesson learned with the first test flight of the SS1 test mule -- the design was marginally stable and the Center of Gravity (CG) must be moved forward to improve its aerodynamic capabilty. There remains a delicate trade-off, though -- I still prefer to keep the liftoff weight low enough to allow the 4-inch version of the SS1 to fly on a G motor.
The dry rocket without any nose ballast weighs 30 ounces, and a G80 weighs just over 4 ounces, for a total of 34 oz. A safe 5:1 thrust to weight ratio for a G80 puts the combined rocket weight at ~52 ounces. Therefore I could add as much as 18 ounces - over a pound - of nose ballast before the thrust to weight ratio starts to become marginal. I used every ounce of that margin, too. The liftoff weight, with motor, was 51.2 ounces.
Two other modifications were included; another half-inch of length was added to the airframe, and I installed a G-Wiz LC flight computer in the nose. Other than re-attach all the dissembled parts, I didn't do anything to pretty the thing up. It had more scars than Frankenstein's monster and looked pretty ugly on the pad.
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The second test flight of the 4" diameter SS1 took place on Saturday, June 4 at a construction site on the north side of Glendale, AZ. I was there at the crack of dawn -- only a slight breeze, temperature about 75°, cloudless sky.
3-2-1-ignition.
Smoke, flame, roar.
Beautiful, perfect boost, straight up. No complications from the airfoil were evident in the flight trajectory.
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Here is the simulation data:
Launch guide data:
Launch guide length: 36.000 In.
Velocity at launch guide departure: 60.344 ft / s
The launch guide was cleared at : 0.355 Seconds
Max data values:
Maximum acceleration: Vert: 197.171 Ft./s/s , Horz: 20.358 Ft./s/s , Magnitude: 197.171 Ft./s/s
Maximum velocity: Vert: 197.525 ft / s , Horz: 0.000 ft / s , Magnitude: 197.668 ft / s
Maximum range from launch site: 34.774 Ft.
Maximum altitude: 664.744 Ft.
Recovery system data
P: Parachute Deployed at : 5.421 Seconds
Velocity at deployment: 51.283 ft / s
Altitude at deployment: 650.193 Ft.
Range at deployment: -31.973 Ft.
Time data
Time to burnout: 1.421 Sec.
Time to apogee: 6.240 Sec.
Optimal ejection delay: 4.819 Sec.
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The RockSim 7.0 model of the 4-inch SS1 is available [HERE!].
The motor was labeled a G80-4 but I don't think it was. If I was to estimate, I would say that the delay was 7 or 8 seconds. Time always seems to slow down during a flight, so without a stopwatch there's no way of knowing for sure -- but it felt like an eternity between burnout and splashdown.
The rocket gods were mocking me that morning, because the ejection charge on the G-Wiz never went off, either.
Perhaps the device saw one too many ballistic landings, and it was deployed one too many times.
At any rate, the rocket piled in. Hard. Only some of the fiberglass parts survived.
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