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astronautix.com N2O4/UDMH

8K84 back
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Oxidiser: N2O4. Oxidiser Density: 1.45 g/cc. Oxidiser Freezing Point: -11.00 deg C. Oxidiser Boiling Point: 21.00 deg C.

Nitrogen tetroxide became the storable liquid propellant of choice from the late 1950's. Nitrogen tetroxide consists principally of the tetroxide in equilibrium with a small amount of nitrogen dioxide (NO2). The purified grade contains less than 0.1 per cent water. Nitrogen tetroxide (N2O4) has a characteristic reddish-brown colour in both liquid and gaseous phases. The solid tetroxide is colorless. N2O4 has an irritating, unpleasant acid-like odour. N2O4 is a very reactive, toxic oxidiser. It is non-flammable with air; however, it will inflame combustible materials. It is not sensitive to mechanical shock, heat, or detonation. Nitrogen dioxide is made by the catalytic oxidation of ammonia; steam is used as a diluent to reduce the combustion temperature. Most of the water is condensed out, and the gases are further cooled; the nitric oxide is oxidised to nitrogen dioxide, and the remainder of the water is removed as nitric acid. The gas is essentially pure nitrogen tetroxide, which is condensed in a brine-cooled liquefier. 1959 production amounted to 60,000 tonnes per year. In carload lots of one-ton cylinders, the price was $ 0.15 per kg. By 1990 NASA was paying $ 6.00 per kg due to environmental regulations.


Fuel: UDMH. Fuel Density: 0.79 g/cc. Fuel Freezing Point: -57.00 deg C. Fuel Boiling Point: 63.00 deg C.

Unsymmetrical Dimethylhydrazine ((CH3)2NNH2) became the storable liquid fuel of choice by the mid-1950's. Development of UDMH in the Soviet Union began in 1949. It is used in virtually all storable liquid rocket engines except for some orbital manoeuvring engines in the United States, where MMH has been preferred due to a slightly higher density and performance. Unsymmetrical dimethylhydrazine (UDMH) is 98 to 99 per cent pure and is described by Military Specification MIL-D-25604. The normally expected impurities are dimethylamine and water. UDMH is a clear, hygroscopic liquid which yellows on exposure to air. It absorbs oxygen and carbon dioxide. UDMH is a toxic volatile liquid. It exhibits the sharp ammoniacal or fishy odour which is characteristic of organic amines. It is completely miscible with water, ethanol, and most petroleum fuels. It is not shock sensitive. The vapours are flammable in air over 2.5 to 95 per cent concentration range. UDMH can be produced commercially by nitrosation of dimethylamine, to N-nitro-sodimethylrtmine, followed by reduction of the intermediate to UDMH and subsequent purification. UDMH can be prepared, also, by a modification of the Raschig process (see discussion of hydrazine), in which the chloramine intermediate is with dimethylamine rather than with ammonia. The price in 1959 for tank-car quantities was under $ 1.00 per kg. Engineering studies indicated a price of $ 1.00 per kg with large scale sustained production. But due to its toxic nature, production and transport costs soared in response to environmental regulations. By the 1980's NASA was paying $ 24.00 per kg.

Engines Using N2O4/UDMH

Eng-engineslink Thrust(vac)-kgf Thrust(vac)-kN Isp-sec Isp (sea level)-sec Designed for Status
RDMT-0.4 X 0 0.00 290   Upper Stages In Production
11D431 1 0.01     Upper Stages In Production
RDMT-8 X 1 0.01 296   Upper Stages Developed 1980's
Stepanov IS/US 1 kgf 1 0.01     Upper Stages Out of Production
RDMT-12 1 0.01 279   Upper Stages In Production
17D58E 1 0.01 247   Upper Stages In Production
DST-25 3 0.03 285   Upper Stages In Production
RDMT-50 5 0.05 255   Upper Stages In Production
11D446 5 0.05     Upper Stages In Production
11D445 7 0.07     Upper Stages In Production
DST-100A 10 0.10 304   Upper Stages In Production
DST-100 10 0.10 276   Upper Stages In Production
RDMT-100 10 0.10 260   Upper Stages In Production
Stepanov LK/LOK 10 kgf 10 0.10     Upper Stages Out of Production
11D428 11 0.11     Upper Stages In Production
RDMT-135 14 0.14 260   Upper Stages In Production
Stepanov IS/US 16 kgf 16 0.16     Upper Stages Out of Production
RDMT-200 20 0.20 255   Upper Stages In Production
DST-200A 20 0.20 300   Upper Stages In Production
DST-200 20 0.20 280   Upper Stages In Production
SE-5-2/-3 21   272      
Isayev TKS attitude 40 0.39     Upper Stages In Production
Stepanov LK/LOK 40 kgf 40 0.39     Upper Stages Out of Production
11D458 40 0.39 252   Upper Stages In Production
RDMT-400A 41 0.40 290   Upper Stages Developed 1980's
RDMT-400 X 41 0.40 296   Upper Stages Developed 1980's
RDMT-400 41 0.40 255   Upper Stages In Production
DMT-600 61 0.60 301   Upper Stages In Production
17D61 300 2.94 326   Upper Stages In Production
KDU-426 315 3.09 292   Upper Stages In Production
KRD-79 315 3.09     Upper Stages In Production
KTDU-417-B 350 3.43 254   Upper Stages Out of Production
Isayev Polet/IS 400 3.92     Upper Stages Out of Production
RD-0225 400 3.92 287   Upper Stages Hardware
KRD-442 447 4.38     Upper Stages In Production
RD-0237 500 4.90 200   Upper Stages Out of Production
RD-866 530 5.20 306   Upper Stages Out of Production
NII 612 kgf 612 6.00 286   Upper Stages Developed
KTDU-80 632 6.19 302   Upper Stages In Production
RD-869 875 8.58 313   Upper Stages Out of Production
YF-23 1,124 11.00 282 260 Upper Stages In Production
RD-857 1,400 13.73 330   Upper Stages Out of Production
RD-0236 1,607 15.76 293 18 Upper Stages Out of Production
11D416 1,670 16.40     Upper Stages Study 1968
KRD-61 1,918 18.80 313   Upper Stages Out of Production
KTDU-425 1,922 18.85 312   Upper Stages Out of Production
KTDU-425A 1,928 18.89 315   Upper Stages Out of Production
S5.92 2,000 19.60 327   Upper Stages Out of Production
S5.98M 2,000 19.62 326   Upper Stages In Production
RD-859 2,045 20.05 312   Upper Stages Hardware
RD-858 2,050 20.10 315   Upper Stages Hardware
RD-864 2,060 20.20 309   Upper Stages Out of Production
RD-868 2,371 23.25 325   Upper Stages Developed 1983-
RD-0231 2,960 29.00 275   First Stages Out of Production
11D430 3,000 29.43 307   Upper Stages In Production
RD-0214 3,150 30.98 293   Upper Stages In Production
RD-0207 3,150 30.90 297   Upper Stages Developed 1961-64
S5.51 3,388 33.20 314   Upper Stages Hardware
11D79 4,500 44.00     Upper Stages In Production
YF-40 5,000 49.00 295 260 Upper Stages In Production
RD-856 5,530 54.23 281   Upper Stages Out of Production
Izotov UR-100 stage 2 vernier 6,000 58.00     Upper Stages Out of Production
Vexin A 7,000 68.60 277 240 Upper Stages Out of Production
Vexin B 7,687 75.40 251 221 First Stages Out of Production
RD-854 7,699 75.50 312   Upper Stages Out of Production
RD-861G 7,796 76.45 325   Upper Stages Developed 1996-
RD-0221 7,954 78.00 330 300 Upper Stages Developed 1965-70
RD-8 7,995 78.40 342   Upper Stages In Production
RD-861 8,026 78.71 317   Upper Stages In Production
Burlak Stage 2 10,000 98.00 330 230 Upper Stages Out of Production
Vexin C 10,108 99.10 251 221 First Stages Out of Production
CZ-1C-3 11,000 107.90 287 258 Upper Stages Developed to 1984
8D725 12,000 117.00 325   Upper Stages Developed 1963-1970
Topaze 12,245 120.10 255 225 Upper Stages Out of Production
RD-0242 12,604 123.60 303   First Stages Developed 1977-83
Izotov LK-700 13,400 131.00     Upper Stages Developed 1966-69
15D13 13,400 131.40     Upper Stages Study 1968
8D423 13,404 131.00 325   Upper Stages Out of Production
R6-117 13,500 132.00     Upper Stages Developed 1964-66
11D423 13,664 134.00 326   Upper Stages Developed 1963-67
RD-862 14,544 142.63 331   Upper Stages Out of Production
RD-0245 21,516 211.00 300 280 First Stages Out of Production
RD-0217 22,330 219.00 313   First Stages Out of Production
RD-0216 22,330 219.00 313   First Stages Out of Production
11D23 23,500 230.50     Upper Stages Study 1968
RD-0235 24,473 240.00 320   Upper Stages In Production
4D10 26,000 255.00     Upper Stages Out of Production
RD-863 28,230 276.84 301 259 First Stages Out of Production
RD-855 29,103 285.40 292 254 First Stages Out of Production
YF-3 29,980 294.00 287 260 Upper Stages In Production
Burlak Stage 1 36,500 360.00 320 270 First Stages Out of Production
RD-0234 53,000 520.00 310 285 First Stages Out of Production
RD-0233 53,000 520.00 310 285 First Stages Out of Production
RD-0204 57,000 559.00 311 278 First Stages Hardware
8D43 57,000 559.00 316 284 First Stages Hardware
RD-0203 57,000 559.00 311 278 First Stages Hardware
RD-0206 59,350 575.50 326   Upper Stages Developed 1961-64
RD-0210 59,360 582.10 327   Upper Stages In Production
RD-0211 59,360 582.10 327   Upper Stages Out of Production
RD-0213 59,360 582.10 327   Upper Stages In Production
RD-0205 62,500 606.40 322   Upper Stages Hardware
RD-0212 62,510 613.00 325   Upper Stages In Production
RD-0244 69,545 682.00 310 280 First Stages Out of Production
Viking 2 70,665 693.00 281 248 First Stages Out of Production
YF-22 73,200 717.80 295 260 Upper Stages In Production
Viking 2B 73,419 720.00 278 248 First Stages In Production
Viking 4 73,518 721.00 296 200 Upper Stages In Production
YF-20A 76,500 750.20 289 259 First Stages In Production
Viking 5C 76,683 752.00 278 248 First Stages In Production
RD-0255 77,000 755.00     Upper Stages Out of Production
RD-0228 77,000 755.00     Upper Stages Out of Production
YF-22A/23A 77,700 762.00 295 270 Upper Stages In Production
YF-22/23 77,700 762.00 295 270 Upper Stages Out of Production
YF-25 80,293 787.40 297 260 Upper Stages In Production
Viking 4B 82,087 805.00 296 210 Upper Stages In Production
YF-20B 83,238 816.30 289 259 First Stages In Production
RD-0243 84,200 825.80 300   First Stages Out of Production
YF-25/23 84,739 831.00 295 260 Upper Stages In Production
RD-250 89,840 881.00 301 269 First Stages Out of Production
RD-252 95,900 940.50 317   Upper Stages In Production
RD-262 96,000 941.00 318   Upper Stages In Production
RD-263 117,777 1,155.00 318 293 First Stages Out of Production
RD-268 126,000 1,236.00 319 296 First Stages Out of Production
RD-273 126,241 1,238.00   296 First Stages Developed 1975-82
RD-253-11D48 166,725 1,635.00 316 285 First Stages In Production
11D43 167,425 1,642.00 316 285 First Stages Developed 1960-64
RD-254 175,000 1,716.00     Upper Stages Developed 1962-66
RD-253-14D14 178,000 1,746.00 317 285 First Stages In Production
RD-275 178,000 1,745.00 317 285 First Stages In Production
RD-253-UR-700 178,000 1,745.00     Upper Stages Designed 1964-1968
RD-253 178,000 1,745.00     First Stages In Production
Press Fed 200k 206,803 2,028.00 306 200 Upper Stages Design concept 1960's
RD-0202 228,000 2,236.00 311 278 First Stages Developed 1961-64
8D43 + 11D43 229,200 2,247.45 310 280 First Stages Hardware
RD-0215 250,000 2,450.00 310 280 First Stages Developed 1962-65
RD-251 270,000 2,643.00 301 269 First Stages In Production
RD-261 309,178 3,032.00 301 270 First Stages In Production
RD-264 461,000 4,521.00 318 293 First Stages Out of Production
RD-274 504,963 4,952.00   296 First Stages Developed 1975-85
RD-270 685,000 6,713.00 322 301 First Stages Hardware
Press Fed 1000k 998,639 9,793.20 300 240 Upper Stages Design concept 1960's
PF N204/UDMH-2165k 2,165,100 21,232.00 267 245 First Stages Design concept 1960's
PF N204/UDMH-2912k 2,911,600 28,552.00 267 245 First Stages Design concept 1960's
Press Fed 5748k 5,748,000 56,368.00 267 245 First Stages Design concept 1960's


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Last update 3 May 2001.
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© Mark Wade, 2001 .