Instrument Readings After Propellant System Pressurization

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The following conditions should be observed after propellant tanks are pressurized with APUs in operation, but before the engine is fired:



System Monitor Panel


  1. Ammonia tanks – Internal tanks, 1445 gallons; external tanks 1053 gallons (approx.).


  1. Liquid oxygen tanks – Internal tanks, 1017 gallons; external tanks, 770 gallons (approx.).

  2. Turbopump hydrogen peroxide (H2O2) tanks – 118 gallons.


  1. Solid fuel (X-15AD-4 airplane only) – Both boosters, 100 percent.

  2. Propellant source (helium) tanks – Both internal and external tanks, 3200-3800 psi.

  3. Engine and propellant control source (helium) tanks – Both internal and external tanks, 3200-3800 psi.

  4. Auxiliary pneumatic and control (helium) tank – 3200-3800 psi.

  5. APU H2O2 tanks – 60-75 gallons, both pointers, gradually decreasing.


  1. APU source (helium) tanks – 3200-3800 psi, both pointers, gradually decreasing.


  1. Liquid N2 tank – 25-30 gallons, gradually decreasing.


  1. Cabin helium tank – 3200-3800 psi, gradually decreasing.

  2. Pilot's O2 (seat) cylinders – 3000-3200 psi.



Main Instrument Panel


  1. Propellant source pressure gauge [69, fig. 5-1] – Both internal and external tanks, 3200-3800 psi.

  2. H2O2 source pressure gauge [57, fig. 5-1] – Both internal and external tanks, 3200-3800 psi.

  3. Propellant tank pressure gauge [71, fig. 5-1] – 45 to 53 psi (both pointers).

  4. External tanks fuel flow indicator [4, fig. 5-1] – 50%.

  5. Propellant pump inlet pressure gauge [72, fig. 5-1] – “L” pointer, 40 to 70 psi; “A” pointer, 40 to 55 psi.

  6. APU source pressure gauge [45, fig. 5-1] – 3200-3800 psi, both pointers, gradually decreasing.


  1. APU H2O2 tank pressure gauge [44, fig. 5-1] – 550 to 610 psi (both pointers), gradually decreasing.

  2. Cabin helium source pressure gauge [40, fig. 5-1] – 1000 to 3400 psi.

  3. Hydraulic pressure gauge [13, fig. 5-1] – 2900 to 3400 psi (both pointers).

  4. Mixing chamber temperature gauge [42, fig. 5-1] – -45° C to -35° C (both pointers).

  5. Generator (AC) voltmeter [22, fig. 5-1] – 195 to 205 volts, both pointers (internal power if generators are ON).

  6. APU bearing temperature gauge [43, fig. 5-1] – 80° C to 130° C (both pointers), gradually increasing.

  7. H2O2 tank and engine control pressure gauge [55, fig. 5-1] – “T” pointer, 0 psi; “C” pointer, 575-600 psi.