Propulsion - Lamar 3/1/96 Progress Report

From: Britney Sandell

The MPS engine selection has been changed to the Marquardt R-4D. Its Specifications are as follows:

Dry Mass: 3.63 kg
Length: 55.41 cm
Thrust: 490 N
Max Diameter: 27.94 cm
Specific Impulse: 312 sec
Propellants: hypergolic nitrogen tetroxide amd MMH or hydrazine, pressure-fed at 0.056 kg/s fuel & 0.091 kg/s oxidizer at 15.2 atm
Burn time: up to 1 hour continuous; 2.67Ns min impulse bit

The number of thrusters needed for a certain lander mass is found in the following table: (Based on the equation Thrust = Mass*Gravity(moon)*3 (Safety factor))

Lander Mass       Thrust       # of thrusters
200  kg             980 N           2
300                1470             3
400                1960             4
500                2450             5
600                2940             6

For the MPS design, we have chosen 6 R-4D thrusters. With that piece of info, the max lander mass, propellant mass and the payload mass was determined. # of thrusters 6
Max Lander Mass 510 kg*
Propellant Mass 779 kg*
Payload Mass 1289 kg* (Keeping within the Delta II constraint of max payload of 1300kg)

**Power Requirements
Thermal Control Subsystem Power Statement (From Artemis Project)

Component               Peak Power (W)       Duty Cycle (% of time turned on)

Main Engines (6 R-4D)      105                          50
RCS Engines  (8)            24                          50
Propellant Lines            48                          50
TOTAL                      177 W 

Next: Continue work on MPS design & pressurization system