DaugerDude
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- Jun 8, 2020
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My multistage LPRs I've custom-designed to use D motors are getting great altitude, like 1830+ feet on a single D12-7 and 2900+ feet on two-stages D12-0,D12-7, measured using a Jolly Logic AltimeterThree. On my next opportunity I'm launching 3 stages. I'm exploring what's possible just with D motors.
A dilemma I've discovered is that the 7-second coast time is not enough. Examining the data out of the AltimeterThree, every time with my design, the ejection charge fires well before apogee. If I'm interpreting the accelerometer data correctly, my rocket is still ascending at 73-86 mph UPWARDS when the ejection charge fires. It is flying higher and faster than OpenRocket originally predicted. So if somehow ejection could be delayed much more than 7 seconds, my rocket's apogee could have been even higher. The parachute is slowing the ascent. Ejection at high speed is corroborated by the torn (repairable or replaceable) parachute.
My ideas so far:
1. Can I buy an Estes D12-14 motor? I can't find that on their motor chart or web site. Can you? But, for real, a D12-7's casing looks pretty full already.
2. The Jolly Logic Chute Release is not really the right solution because then I have a bound-up parachute wagging around on a 80 mph ascent. I'd like the rocket to continue to be aerodynamic until after apogee.
3. Adding an A (somehow?) after the D12-7 doesn't seem to be enough because those delays are only 3 seconds, and how would the A's thrust not damage the rocket?
4. The safest seems to be redesign or adapt the top stage to use a C6-7 to shave Max Speed (perish the thought!) and end up slower at ejection, but I'd guess that lowers the apogee too. I can check OpenRocket. (My rocket is too fast?!?)
5. Is there a Zero0-7 motor? Something with zero impulse, zero thrust, and a 7 second delay? I could tape that on top of the D12-7 maybe?
(5a. Carefully cleave a D12-7 into a D12-0 and a Zero0-7? Any tips?)
6. Is there electronics that fit a BT-50 LPR that will cause this kind of extra delay? But even if I did that would add weight, lowering apogee.
Any other ideas? Thanks in advance.
A dilemma I've discovered is that the 7-second coast time is not enough. Examining the data out of the AltimeterThree, every time with my design, the ejection charge fires well before apogee. If I'm interpreting the accelerometer data correctly, my rocket is still ascending at 73-86 mph UPWARDS when the ejection charge fires. It is flying higher and faster than OpenRocket originally predicted. So if somehow ejection could be delayed much more than 7 seconds, my rocket's apogee could have been even higher. The parachute is slowing the ascent. Ejection at high speed is corroborated by the torn (repairable or replaceable) parachute.
My ideas so far:
1. Can I buy an Estes D12-14 motor? I can't find that on their motor chart or web site. Can you? But, for real, a D12-7's casing looks pretty full already.
2. The Jolly Logic Chute Release is not really the right solution because then I have a bound-up parachute wagging around on a 80 mph ascent. I'd like the rocket to continue to be aerodynamic until after apogee.
3. Adding an A (somehow?) after the D12-7 doesn't seem to be enough because those delays are only 3 seconds, and how would the A's thrust not damage the rocket?
4. The safest seems to be redesign or adapt the top stage to use a C6-7 to shave Max Speed (perish the thought!) and end up slower at ejection, but I'd guess that lowers the apogee too. I can check OpenRocket. (My rocket is too fast?!?)
5. Is there a Zero0-7 motor? Something with zero impulse, zero thrust, and a 7 second delay? I could tape that on top of the D12-7 maybe?
(5a. Carefully cleave a D12-7 into a D12-0 and a Zero0-7? Any tips?)
6. Is there electronics that fit a BT-50 LPR that will cause this kind of extra delay? But even if I did that would add weight, lowering apogee.
Any other ideas? Thanks in advance.
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