Engines and Fuel System

The variable exhaust nozzle system automatically controlled the exhaust area to provide for optimum thrust and specific fuel consumption under varying engine operating conditions. It also protected the engine from overheating. The system consisted of primary and secondary nozzle flaps, plus associated control units and actuators. Each primary nozzle control was mechanically interconnected with the engine throttle and synchronized so that throttle movement would automatically result in proper primary engine nozzle setting. The secondary nozzles were used to provide maximum thrust and reduced drag during cruise and military operating ranges. These were opened during idle and afterburner operation, and were closed for operations in the cruise and military ranges.

Each engine nacelle was equipped with a variable-position spike which could be moved forward or aft in the inlet to maintain an efficient airflow to the engine throughout the speed range of the aircraft. During normal operation, control of the spike was completely automatic. The spike remained in the aft position until an airspeed of Mach 1.42 was reached. At that speed, a switch in the air data computer closed and activated the system. The transducer then moved the spike forward to the appropriate location for the particular airspeed. Engine cooling was provided by using two scoops located in the air inlet of each nacelle. Ram air was passed via these scoops through a series of bypass flaps into the hydraulic oil cooler, then aft between the engine and the nacelle walls to be expelled into the engine exhaust gases.

The fuel system was the most complex and sophisticated yet installed in an operational aircraft due to the tight space restrictions, the problem of fuel "stacking" or movement of fuel in the tanks due to high-G manuevers, and complex center of gravity requirements to keep the airplane properly balanced. The JP-4 fuel was stored in four main tanks, termed forward, aft, reservoir and balance units. Two more fuel tanks were installed in the under-fuselage pod (a total of 4,172 US gallons in the MB or LA pod and 3,885 US gallons in the TCP pod). The fuel system could operate with or without the pod being installed. The forward portion of both wings, as well as the fuselage volume between bulkheads 5 and 6 comprised the forward tank, which could accommodate up to 3,202 US gallons of fuel. The aft portion of both wings and the fuselage volume between bulkheads 9 and 12 comprised the aft tank, which was capable of carrying up to 5,893 US gallons of fuel. The fuselage section between bulkheads 6 and 8 comprised the 610-gallon reservoir tank, and the fuselage section between bulkheads 12 and 19 comprised the 1,219-gallon balance tank. The reservoir tank acted as an accumulator tank by utilizing an autotransfer system which maintained a specified tank level until the other tank supplies had been depleted. The balance tank was not used for direct engine supply, but fuel could be transferred from the balance tank to the forward tank when needed. The center of gravity could be maintained either automatically or manually by transferring fuel between the forward, aft and balance tanks.

The B-58 was equipped with a mid-air refueling system, mounted in the upper portion of the nose radome some 45 inches ahead of the pilot's windshield. It consisted of a receptacle for a KC-135A flying boom probe. When not in use, the system was covered by a door which was normally flush with the contour of the radome. When the slipway door was opened, it formed a guide for the entry of the flying boom. The refueling system was widely regarded by pilots as one the easiest to use ever developed.

The B-58 was also equipped with an emergency fuel dump system. The fuel could be dumped via a probe which extended two feet outward from the left side of the balance tank just aft of the wing trailing edge.

Wings, Tail, Control Systems and Landing Gear Defensive Systems and Electronics Offensive Systems and the Pod The TB-58A Trainer Operational History Aftermath Reconnaissance Testbed ALBM Proposed Origin and Development Fuselage Structure and Crew Stations Engines and Fuel System

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