Saturday, November 22, 2008

Prochron 0811B

It's official: Prochron 0811B specs

Booster on pad: RTL fuelled: 695kg
Booster on pad: RTL unfuelled: 141kg (Stage One installed)
Booster on truck: not fuelled: 75kg (Stage One not installed)

Stage One: Cesaroni M4770-P http://www.pro38.com/motor/M4770-P.html 6.6kg total per module; ten modules
Stage Two: Prochron module * 3
Stage Three: Prochron module *1
Stage Four: Prochron upper stage

Cesaroni M4770-P: 6.6kg rocket stage, 3.1kg at burnout, 2043m/s exhaust speed. Stages at 107m/s elapsed serial delta-v after 2.0sec. Average thrust: 4770N (47.7kN vehicle)

Prochron module: 150kg loaded, 15kg empty. Average exhaust speed 2400m/s first stage, 3000m/s further stages. Estimated 20cm diameter, 5m long (avg. density 0.75kg/L). Average thrust: 2500N (tentative; 7500N Stage Two.) Estimated burn time: 162sec (assumed constant thrust)

Prochron Upper stage: 20kg loaded, 6kg empty. Average exhaust speed 3000m/s. Estimated 20cm in diameter, 0.6m long. Average thrust: 250N Estimated burn time: 168sec (assumed constant thrust)

Fairing: 4kg, payload 5kg (i.e.: 3kg Cubesat plus 2kg deployer)

Accomplishments:
1. 3:1 Stage Two: Stage Three found optimal, needs to be verified with better optimizer
2. 6m launch tower estimated exit speed at 27m/s based on http://www.thrustcurve.org/motorguide.jsp?rocket=400

Objections:
1. Calculated Delta-v only 9258m/s due to previously undetected error in optimizer. Would have to be air launched.
2. Module burn times are too long. Try to get them under 120sec. A cost/practical requirement of the Prochron is to achieve orbit before crossing the launch site horizon.
3. Amateur/Sounding version compatibility is not known.
4. Full fledged solids in 1st stage vs. preferred hybrids. Solids are kit reloadable and made in Canada (the plus side.)
5. Does this preliminary study leave enough room for recovery systems?

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