From my V2.1 flight over the weekend.
These are the readouts from the two HCX avionics computers, each with separate sensor arrays, yet with remarkable agreement of 1.14 miles of altitude reached.
I’ll mark various interesting tidbits in the notes above.
Interesting information. The burning-time of the motor is approx 5sec. At this time, the rocket is approx at a one fifth of its maximum altitude and of course at its maximum velocity. The apogee occurs at 20sec (null velocity).
I think the solid motor puts a high thrust at short burning time and a low thrust at long burning time. Therefore, for seeing the burning rate, could be useful a zoomed frame of the acceleration curve in the first 5sec. Is it much noisy?
OTOH, the two spikes at the right hand end of the figures have different time lag. IMHO the upper (lower) figure corresponds with the upper (lower) sensor. The first shock is registered by both sensors almost simultaneously (rocket landing in vertical position). The second shock in the botton sensor is the bounce with the nozzle (the rocket is just not vertical), whereas the second shock registered by the upper sensor is when the nose touches the land. Am I right on this?
Cool. 10 Gs for a bit less than two seconds, then ballistic to apogee for another 15s or so.
Remarkably little air drag, indicated by the straightness of the decelerating speed curve.
Was chute deployment just from HCX#1 or did you have a redundant setup?
(edit: I didn’t see the previous comment go up when I was composing this. Redundancy left as written.)
WOW Steve! You have way too much fun : ). I used to launch model rockets as a kid and now my young daughter (almost 4) is showing interest after watching a shuttle launch. She has begun building her own ‘spaceships’ but I think she is too young to build and launch a model rocket. I’m in the Palo Alto region too, is there any public place nearby where I can take her to watch some launches?
Jaako: That is definitely the perception. It’s like roller coasters (or football games). The actual time lapse of action is much less than we feel. There are some moonburner motors that last longer, 7-9 seconds, and then you can also stage the motors. I plan to launch this rocket on a 7-second Aerotech N2000 on Saturday.
r.Al(-): I started with Estes with my son when he was 3. My daughter did not like the noise at that age, so 4 or 5 might be a better start time. And yes, you are luckily in the area with the largest rocketry club, LUNAR. The launches at NASA Ames are the best place to start.
Go for it!
P^2: Redundant computers are required on all M-motor flights and above. Each of the HCXs here connected to an e-match programmed to fire at apogee. Both of them run into a common pouch of 15g of black powder (I did not double up on that because one would almost inevitable ignite the other even when separated by PVC pipe segments. So I cannot confirm after the fact if both fired properly (or just one).
Motor: Here is the Thrustcurve. It is supposed to burn for 5.2 seconds (and the package said 4.4 seconds), but mine seems to have finished in 2.1 seconds. The altitude was a bit less than RockSim predicted, but not drastically…. Strange. I wonder if I had a fast burn or a partial burn…
Skeptical_thinker: here is the detail from the first couple seconds, with 500 samples/second:
Thanks for the pics. I guess you had a fast burn. I’m sending you email with some details.
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