The B-29 is designed to permit you to fly at high altitude without the usual disadvantages of extreme cold, diminished pressure, and decreased oxygen. This is done by the use of pressurized, heated compartments. A highly efficient oxygen system is also incorporated in the ship for use when the cabins are unpressurized.
Fig. 13
Fig. 13
PRESSURE CABINS
There are three pressure compartments in your ship: Forword, Aft, and Tail. (See Fig. 13). The forward and aft cabins are connected by a communicating tunnel running over the bomb-bay; the tail compartment is isolated when pressurized.
OPERATION: The cabins are pressurized from the superchargers of the two inboard engines. Your flight engineer controls the air-flow from these superchargers, permitting the cabin Pressure Regulators to automatically regulate the air pressure within the cabin. From ground level to 8,000 ft the cabins are not pressurized. When the cabins are under pressure, your cabin altitude will remain at 8,000 ft, while the ship is flying at any altitude up to 30,000 ft. When your ship gets about 30,000 ft, the cabin pressure will rise proportionately so that it reaches about 12,000 ft when the ship is at 40,000 ft. (See Fig. 14 for this pressure relation). Cabin temperature is controlled by thermostat.
Fig. 14
Fig. 14
EMERGENCY PRESSURE RELEASE. Since all emergency doors open in, cabin pressure must be released in all emergencies. This is done by a valve controlled by cable from:
WHEN DO YOU NEED OXYGEN IN A B-29?
As long as the cabin altitude is below 10,000 ft you're O.K. without oxygen.
YOU MUST USE OXYGEN when the CABIN ALTITUDE goes ABOVE 10,000 feet.
This may occur:
OXYGEN SYSTEM
GENERAL:
Your oxygen system is a low pressure demand system with 14 oxygen stations corresponding to the various crew positions. The system utilizes the same type of equipment described for the Heavy Bombers:
DISTRIBUTION:
In the earlier B-29's, the oxygen cylinders were located in the center wing section. At present, however, the cylinders are distributed through the aft-portion of the ship. Regardless of the location of cylinders, distribution is essentially the same. This distribution is highly efficient. The entire loss of the O₂ supply to several crew positions has been practically eliminated by the following principle.
Brief study of the diagram of the oxygen supply to a typical B-29 station (Fig. 15) will demonstrate the safety factors of this dual source supply.
Exact location of every oxygen cylinder and supply line may be found in the late tech orders.
PORTABLE EQUIPMENT
Two types of walk-around bottles are furnished in the B-29:
SERVICING:
See Page 47 for servicing instructions. The filler valve is located on the left side of the fuselage.
Fig. 15
Fig. 15
EXPLOSIVE DECOMPRESSION
With the use of pressurized compartments there is a possibility of explosive decompression. This is most likely to occur if a blister is blown either due to gunfire or a defective blister. Due to the excess capacity of the superchargers, small cabin holes will not cause explosive decompression. If explosive decompression occurred at 30,000 ft, the pressure altitude of the cabins would change from 8,000 ft to 30,000 ft in less than one second. What would happen in such a case?
PHYSICAL EFFECTS:
The human body is affected very little by explosive decompression. IF YOU GET OXYGEN YOU WILL SUFFER NO HARMFUL EFFECT. You may feel a little distension of the belly or a little rush of air from the lungs, but this is generally slight and of no consequence. Your ears should clear automatically since you are going up, not down. The only dangers of explosive decompression are as follows:
DANGERS:
WHAT TO DO?
The important thing in explosive decompression is to get oxygen rapidly. To get oxygen rapidly you MUST at all times:
In case of explosive decompression, adjust your mask to the face and fasten the hook on your helmet. You will then be O.K.
Fig. 16
Fig. 16
HIGH ALTITUDE BAIL-OUT
If you must bail out above 20,000 feet, use the FREEFALL TECHNIQUE described on page 23 except that you have an additional oxygen source for bail out. Use the H-2 cylinder connected to your A-14 mask (Fig. 16) as an oxygen supply DURING FREE FALL. Just before jumping, pull the rip cord release on your H-2 cylinder. DO NOT OPEN YOUR CHUTE AT HIGH ALTITUDE.
--REPRODUCED BY--Reproduction Dept.Army Air Field Lincoln, Nebr.10-18-44 20 M