Phoenix-1B Mk II Hybrid Sounding Rocket

Overview

The Phoenix-1B Mk II is a single-stage unguided ballistic sounding rocket powered by the PV-3 hybrid rocket motor. The primary mission of the P-1B Mk II is to reach an apogee altitude of 35 km. As the Mk II of the P-1B series, it incorporates a number of improvements upon its predecessor including the use of aluminium additive in the fuel grain to reduce the nominal O/F ratio and a composite oxidiser tank to reduce the vehicle inert mass.

The vehicle is 4.92 m long with a diameter of 0.17 m at the tank and 0.164 m at the motor. It has an inert mass of 47 kg, a propellant mass of 41 kg, and a total mass of 88 kg. The motor uses 34 kg of nitrous oxide as the oxidiser and 7.05 kg of paraffin wax with aluminium additive at 20% for the fuel. A metallised fuel grain has the potential to increase the specific impulse and reduce the O/F ratio, thus reducing vehicle weight. 
 

PV-3 Hybrid Rocket Motor

The PV-3 hybrid rocket motor has a nominal thrust and chamber pressure of 7250 N and 40 bar respectively with a burn time of 14.2 s. It operates via blowdown feed system whereby the oxidiser tank ullage is supercharged with helium to 65 bar to drive the oxidiser into the motor. 

PV-3 motor cross-section

1) Injector bulkhead, 2) Injector plate, 3) Bulkhead insulation, 4) Pre-combustion chamber insert, 5) Fuel grain, 6) Thermal liner, 7) Chamber casing, 8) Post-combustion chamber insert, 9) Nozzle.

Oxidiser Tank

A composite oxidiser tank was designed to be used on the P-1B Mk II to reduce vehicle inert mass compared to the P-1B Mk I, which utilized an aluminium tank. The tank was manufactured using 4-axis filament winding machine using a T800 carbon/epoxy composite. The tank liner was formed using a uPVC pipe in conjunction with aluminium bulkheads due to nitrous oxide compatibility constraints and material availability. The tank was designed for a MEOP of 80 bar with a minimum safety factor of 2.25 for all loading conditions. The bulkheads are fixed using stainless steel locator pins and has a dual EPDM O-ring seal.


1) Top bulkhead, 2) Bottom bulkhead, 3) PVC liner, 4) Locator pins, 5) Dual O-ring seal.


Technical Specifications

Fuel   Paraffin wax  Design apogee   35 km 
Oxidiser   Nitrous oxide    Vehicle mass   88 kg
Fuel additive   Aluminium (20%)    Vehicle length   4.92 m
O/F ratio   5.4    Vehicle diameter   0.17 m 
Thrust   7250 N    Range   24.8 km 
Tank pressure   65 bar   Max. speed   Mach 2.31 
Chamber pressure   40 bar    Max. acceleration   6.14 g
Burn time   14.2 s    Flight time   136 s
Total impulse   76 537 Ns        
Specific impulse   192 s        

Testing

Cold flow test:


Hot-fire test:


Launch test:


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