Re: Picture of J58 (SR-71 Engine) running hot at Edwards


Message posted by Peter Merlin on June 21, 2008 at 10:20:49 PST:

Propulsion for the Blackbirds consisted of two Pratt & Whitney JTD-11B-20 (J58) afterburning turbojet engines.

The forward compressor stages and inlet case were made of titanium alloys, including Ti-8-1-1 and Ti-5-2.5, because these have good creep (expansion and contraction) properties at temperatures up to 850 degrees F. The first-stage turbine vanes incorporated Mar-M-20ODS, a nickel-base alloy that was cast with spanwise columnar crystal grains. Its granular structure reduced the risk of thermal shock cracking. Some first and second stage turbine blades, second-stage turbine vanes, and afterburner nozzle flaps were made from another nickel-base alloy, IN-100.

The diffuser case was constructed using Inconel-718 nickel alloy, capable of withstanding 1,250 degrees F. Most J58 engine components were made of Waspalloy, an oxidation-resistant nickel-base alloy capable of withstanding 1,400 degrees F, but burner components were fashioned from Hastelloy-X.

Turbine disks were made of Astralloy, a precipitation-hardened nickel-base alloy suitable for operations up to 1,500 degrees F. This extremely expensive material was available as a forging, and had creep and tensile strength qualities superior to Waspalloy. Parts with similar applications to Hastelloy-X, but requiring greater resistance to buckling and sliding wear, were made of L-605 (Haynes 25). A cobalt-base alloy, L-605 was easy to weld and form. This was later replaced with Haynes 188 and Haynes 230, which had improved oxidation resistance.

The exhaust ejector on each engine was supported by streamlined struts and a ring of Rene‘ 41 on which were hinged free-floating trailing edge flaps of Hastelloy X and Inconel. During afterburner operation, these flaps experienced maximum temperatures of 1,400 degrees F on their inner surfaces and 1,600 degrees F on outer surfaces.


In Reply to: Picture of J58 (SR-71 Engine) running hot at Edwards posted by Randall on June 20, 2008 at 19:37:27 PST:

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