F from 2.25 Ib(=10 N)to 26,000 lb( Shuttle RCS) arge experience base(but less than monop Relatively complex system Short Pulsing difficult but can do re-starts Toxic propellants Better Isp than monoprop High cost (1c) Solid Propellant(Aluminized HTPB/AP typically) Ip≈280-300sec F from 10/b to very large boosters Simple integration(no plumbing) Very light casing and inerts(=15-20%of propellant) Isp comparable to biprops Non-restartable 1-5% dispersion in impulse direction (requires trim engines for precise maneuvers) Moderate-to high cost (2)Electrical Broad range of power and Isp. Cost moderate to high(excluding power systems) IV (2a) Electrothermal(Heated hydrazine, heated H2 or heated waste gas) High n, low Isp Very simple, limited by material T Can raise monoprop. n Ha to Isp s 310sec (Intelsats) With H2, Isp s 700sec(but storage problems) Allows efficient waste gas disposal(Space Station) (2b) Arciets(with hydrazine, ammonia, H2) n=0.4, Isp= 600s(hydrazine 700s(ammonia) 1000s(H2) P from 0.5 KW to 30 KW(or as available Moderately high F/P=2n (good if mission time limited High operating T(thermal isolation difficult Efficiency not very Some flight experience base (Telstar) Relatively simple Power Processing Unit(PPU) 16.522, Space P rtinez- sanchez Lecture 1a Prof. Manuel martinez Page 2 of 316.522, Space Propulsion Lecture 1a Prof. Manuel Martinez-Sanchez Page 2 of 3 F from 2.25 lb ( ) ≈ 10 N to 26,000 lb (Shuttle RCS) Large experience base (but less than monop.) Relatively complex system Short Pulsing difficult, but can do re-starts Toxic propellants Better Isp than monoprops. High cost (1c) Solid Propellant (Aluminized HTPB/AP typically) Isp ≈ 280 - 300sec F from ≈ 10lb to very large boosters Simple integration (no plumbing) Very light casing and inerts ( ≈ − 15 20% of propellant) Isp comparable to biprops. Non-restartable 1-5% dispersion in impulse, direction (requires trim engines for precise maneuvers) Moderate-to-high cost (2) Electrical Broad range of power and Isp. Cost moderate to high (excluding power systems) 2 F Fc = = 2m 2 IV IV η i (2a) Electrothermal (Heated hydrazine, heated H2 or heated waste gas). High η , low Isp Very simple, limited by material T Can raise monoprop. N2H4 to Isp ≈ 310sec (Intelsats) With H2, Isp ≈ 700sec (but storage problems) Allows efficient waste gas disposal (Space Station) (2b) Arcjets (with hydrazine, ammonia, H2) η ≅ ≅ 0.4, 600 Isp s (hydrazine) 700s (ammonia) 1000s (H2) P from 0.5 KW to 30 KW (or as available) Moderately high 2 F P c η = (good if mission time limited) High operating T (thermal isolation difficult) Efficiency not very high Some flight experience base (Telstar) Relatively simple Power Processing Unit (PPU)