Six Turning, Four Burning: The story of how the Iconic B-36 Peacemaker got the Jet Engines

Six Turning, Four Burning: The story of how the Iconic B-36 Peacemaker got the Jet Engines

By Dario Leone
Apr 6 2024
Sponsored by: Osprey Publishing
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The Peacemaker

Conceived during 1941 in case Germany occupied Britain, when US bombers would then have insufficient range to retaliate, the B-36 Peacemaker was to be primarily a ‘10,000-mile bomber’ with heavy defensive armament, six engines and a performance that would prevent interception by fighters. Although rapid developments in jet engine and high-speed airframe technology quickly made it obsolescent, the B-36 took part in many important nuclear test programmes.

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As explained by Peter E. Davies in his book B-36 ‘Peacemaker’ Units of the Cold War, the main criticism of the B-36B, as it achieved effective operational status, was its lack of speed – a shortcoming that became more significant as jet fighter performance steadily increased. Extra power from add-on jet engines was a low-cost compromise after the cancellation of Variable Discharge Turbines (VDT). Other proposals involving Wright T-35 or Northrop T-37 Turbodyne advanced turboprop engines were considered. As a quick solution, the proven General Electric J47 turbojet was favoured for installation in the B-36D, subsequent variants and the re-manufactured B-36A/Bs.

B-36 gets the Jet Engines

As a relatively lightweight engine developing 5200 lbs of thrust, the J47 could be mounted in podded pairs beneath each outer wing. The jets were intended for use on take-off to increase the potential combat load by up to 40,000 lbs and to boost dash speed over the target to 460 mph. When combined with the bomber’s 40,000-ft altitude, rapid climb and fast run to the target area, such a speed would have complicated an intercepting fighter’s job.

For take-off, the jets were usually cranked up to 100 per cent power, allowing a loaded B-36 to get airborne well before the end of a SAC runway and climb away at 2000-3000 ft per minute. They could also be used together with an adjustment of the fuel mixture for the reciprocating engines to achieve rapid acceleration and a steep climb to high altitude in order to evade fighters.

The jet pods were slightly adapted from the versions manufactured for the inboard engines of the B-47. Their support struts and aerodynamic fairings were essentially the same and their taxi light installations were also retained. Each pod held a pair of J47-GE-19 turbojets, modified to burn the same aviation gasoline as the B-36’s Wasp Major piston engines, albeit with a slight reduction in thrust. They had adjustable ‘iris blade’ aerodynamic covers that extended over the jet air intakes to reduce engine windmilling when the jets were not in use.

Six Turning, Four Burning

B-36B 44-92057 had the paired nacelles installed ready to start flight tests on Mar. 26, 1949, although it retained the J35A-19 engines used in the B-47 as J47s were not available at the time. Installing them outboard on the B-36’s very strong wings required little structural alteration or reinforcement. The extra weight of the pods on the outer wings did, however, slightly reduce lateral manoeuvrability, and the lack of powered flying controls became more noticeable.

With ten engines in operation (‘Six Turning, Four Burning’), the not-infrequent loss of one or even two engines in flight was manageable. On rare occasions B-36s returned with all three reciprocating engines on one wing feathered, as long as the jets on that wing were running. When a crew informed an air base’s air traffic control that they had a failed engine or two, they would be routinely asked if they wished to declare an emergency. The usual reply was, ‘It’s okay. We still have eight left’.

The J47s could also help to maintain stable flight if several ‘recip’ engines on one side failed. The engines’ throttle systems operated on pairs of inboard and outboard jets to prevent asymmetric thrust, and consequent instability, occurring. The B-36’s extraordinary ‘engine out’ survivability was demonstrated by Capt Barry H Young of the 7th BW on Dec. 10, 1954. In an outstanding demonstration of piloting skill, he managed to land safely with all three piston engines on one wing feathered, no jet engines and no flaps.

B-36 ‘Peacemaker’ Units of the Cold War is published by Osprey Publishing and is available to order here.

Photo credit: Lt. Col Frank F. Kleinwechter / U.S. Air Force

Five turning, one not! Rare photo shows B-36 Peacemaker flying with number 3 propeller “feathered”

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Dario Leone

Dario Leone

Dario Leone is an aviation, defense and military writer. He is the Founder and Editor of “The Aviation Geek Club” one of the world’s most read military aviation blogs. His writing has appeared in The National Interest and other news media. He has reported from Europe and flown Super Puma and Cougar helicopters with the Swiss Air Force.
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