1 / 16

X-ray Wide Field Imager

X-ray Wide Field Imager. Propulsion Bob Estes 16 – 20 April, 2012. Summary. Monopropellant (Hydrazine) Propulsion subsystem operating in a blow-down mode Three 22 inch spherical propellant tanks with diaphragms Thrusters: Twelve 22N thrusters (Aerojet MR-50E)

kyros
Download Presentation

X-ray Wide Field Imager

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. X-ray Wide Field Imager Propulsion Bob Estes 16 – 20 April, 2012

  2. Summary • Monopropellant (Hydrazine) Propulsion subsystem operating in a blow-down mode • Three 22 inch spherical propellant tanks with diaphragms • Thrusters: Twelve 22N thrusters (Aerojet MR-50E) • Propellant Mass: 148.6 kg (6.4 kg GN2) based on 3300 kg wet • Subsystem Dry Mass: 38.1 kg • Subsystem is single-fault tolerant (dual-fault tolerant wrt Range Safety) • All components are TRL9

  3. Propulsion Subsystem Schematic N2 N2H4 N2 N2H4 N2 N2H4 P P P Diaphragm Tanks F 22 N Thrusters FD Valves Pressure Transducer Filter Latch Valve F P

  4. Propulsion Subsystem Drivers • Provide ΔV for 3300 kg maximum launch mass (wet mass) • Provide 6 DOF to spacecraft via thrusters • Unload momentum wheels • Size the propulsion system for 5 years at L2 at maximum launch mass • Single fault tolerant, graceful degradation • Dual fault tolerant with respect to range safety • Minimize plume contamination to mirror and radiators • Minimize product qualification Total = 91 m/sec

  5. Propulsion Subsystem Description • Mono-Propellant, blow-down system using hydrazine fuel • Three diaphragm propellant tanks • Diameter ~22 inch • Each holds up to 63.5 kg of fuel in blowdown mode (required = 49.5 kg each) • Twelve 22-N thrusters • Thrusters arranged in 2 banks to provide redundancy • Thrusters provide 6 DOF • Dual coil thrusters • Dual coil latch valves • Pressurant side of tanks isolated to ensure equal draining • Dedicated transducers provide propellant knowledge for individual tanks P P P N2 N2H4 N2 N2H4 N2 N2H4 Diaphragm Tanks F 22 N Thrusters FD Valve Latch Valve Pressure Transducer Filter F P

  6. ΔV Budget • Propellant was budgeted for a 3300 kg S/C (including propellant mass) • Nominal ΔV = 91 m/s. Adding 10% Attitude Control (AC) tax and 0% Margin increases total ΔV to 100.1 m/s. • ΔMass Sensitivity chart for tank capacity margins • Specific Impulse (Isp) assumes 10⁰ degree cant in two planes. (227 sec represents average over full pressure range) • Total propellant mass = 148.6 kg • Maximum continuous burn = 2295 seconds (~38 minutes), Launch Window+Dispersion

  7. ΔMass Sensitivity • Baseline = 148.6 kg • Propellant was budgeted for 91 m/sec + 10% ACS penalty = 100.1 m/sec • Isp = 227 sec (10⁰+ 10⁰ cant) 22 N class thrusters • Max load = 191.5 kg (3 x 5555 in3 tanks, 400 – 100 psi blowdown, 50 – 10 C)

  8. Propellant Tanks • 3 spherical diaphragm tanks with tab mounts • ATK Part No. 80259-01 • Volume = 5,555 in3 (one tank) • Propellant Capacity • 72 kg each (qualified max) • 64 kg for 400 – 100 psi blowdown, 50 – 10 ⁰C • Titanium Construction • Mass = 7.27 kg each (standard, light version = 6.4 kg) • Diameter = 22.14 in. • MEOP = 475 psi • BOL 400 psi @ 50C for this mission • Tank will blow down to ~ 164 psi at 10 ⁰C

  9. Blow-Down Curve BOL L2 Thruster Operating Range Launch Window LV Dispersions MCC Orbit Maintenance

  10. Thrusters • Twelve Aerojet MR-50E monopropellant thrusters • 22 N (5 lbf), • Extensive flight heritage • Sizing: • ΔV • Four 22N thrusters complete largest maneuver (Launch window+LV Dispersion Correction - 55 m/s) in about 38 minutes • Thruster qualified for hundreds of minutes continuous firing • ΔH (momentum change) • Unloads expected to be infrequent (~ 75 days) • Minimum impulse bit @ 400 psi~ 0.4 Ns x moment arm • Estimated propellant required for ΔH is 0.5 kg • Assume unloading 122.5 Nms every 75 days for 5 years • Pulse Life • Maximum number of pulses ~ 12000 for ΔH • Thruster qualified for >> 100,000 pulses

  11. Thruster Installation(Note: 3.5m Bus Hex Shown) Provide 6 DOF and redundancy in the event of thruster failure 8 Thrusters canted 10⁰ in two planes Thrusters arranged in balanced couples as seen by intersecting lines of action Cover/Shade Three Tanks 4 Thrusters canted 45⁰ in one plane Notional CG Solar Array Lines of Action

  12. Master Equipment List • All components are TRL-9 • Power • Thruster Cat-Bed Heaters = 3.85 Watts each. Minimum of 4 heaters powered for one hour before maneuvers • Pressure Transducers = 1 Watt each. 2 pressure transducers powered continuously • Valve, line and tank heaters booked by Thermal subsystem

  13. Issues and Concerns & Future Work • Investigate current BL thruster configuration for adequacy • Torque “bit” • Redundant modes • Latch valve grouping • Cant angles • Low mass of S/C may allow 1 lbf (5N) thrusters • Radiator location and sensitivity to plume not yet defined • Reported propellant budgets based on estimated launch masses • Atlas LV has launch capacity beyond BL tankage capacity • Falcon 9 launch mass (~2400 kg) may be possible • Investigate other configurations • May be able to use single PMD tank (saves 12 kg in tank mass + fewer components) • Smaller diaphragm tanks save (4 kg) • Match thruster class and position to torque requirements (with margin) – smaller thrusters?

  14. Acronym list AC – Attitude Control BL – Baseline BOL – Beginning of Life Cat-Bed – Catalyst Bed (thruster) DOF – Degree of Freedom FD Valve – Fill and Drain Valve GN2 – Gaseous Nitrogen ΔH – Momentum change Isp – Specific Impulse, sec LV – Launch Vehicle MCC – Mid-Course Correction MEOP – Maximum Expected Operating Pressure MR – Monopropellant Reaction (Engine) PMD – Propellant Management Device sec - seconds ΔV – Change in velocity

  15. Backup

  16. Propulsion Labor • Total FTEs = 12.9 • Cost assumes In-House build at GSFC and covers the following tasks: • Propulsion subsystem design and analysis • Procurement activities (component purchases and contract management) • Propulsion subsystem assembly • Propulsion subsystem testing • Propulsion support during S/C level I&T • Launch site support • Note: FTEs do not include thermal design, drawing production, support structure fabrication, or electrical harness integration.

More Related