Pratt & Whitney TF30

Pratt & Whitney's TF30 was a military low-bypass turbofan engine originally designed for the subsonic F6D Missileer missile carrier, but this project was cancelled. It was later adapted with an afterburner for supersonic designs, and in this form it was the world's first afterburning turbofan, going on to power the F-111 and the F-14A Tomcat as well as some versions of the A-7 Corsair II without an afterburner. First flight of the TF30 was in 1964 and production continued until 1986.

Supersonic jets before the introduction of the TF30 all used afterburning turbojet engines as opposed to turbofan engines. A turbojet engine's entire volume of intake air is directed through the engine core, whereas in a turbofan design, a significant percentage of the intake air is routed around the core. Turbofan engines deliver much improved fuel burn efficiencies over turbojets. An afterburning turbofan combines the fuel economy of a turbofan with the greatly increased thrust produced by an afterburner.

F-111

The F-111A/E used the TF30-P103 (aka P-3) turbofan. [Federation of American Scientists. [http://www.fas.org/man/dod-101/sys/ac/f-111.htm F-111] .] The F-111 had problems with inlet compatibility, and many faulted the placement of the intakes behind the disturbed air of the wing. The F-111 went through several different intake configurations. D and F models used redesigned inlets and improved engines. The F-111D used TF30-P-9, and the F-111F used TF30-P-100. The F-111 has a very long range/large payload due to its variable geometry wings, and the use of the TF30.

F-14A

The F-14 Tomcat with the TF30-P-414A [Federation of American Scientists. [http://www.fas.org/man/dod-101/sys/ac/f-14.htm F-14 Tomcat] .] was underpowered, because it was the Navy's intent to procure a jet fighter with a thrust-to-weight ratio (in clean configuration) of unity or better (the US Air Force had the same goals for the F-15 Eagle and F-16 Fighting Falcon). The F-14A's thrust-to-weight ratio was similar to the F-4 Phantom II; however the new fuselage and wing design provided greater lift and a better climb profile than the F-4. The TF30 was found to be ill-adapted to the demands of air combat, and was prone to compressor stalls at high angle of attack if the throttles were moved aggressively. While some pointed to a problem predominating at high altitude, in fact the problem could occur at any altitude. On October 25, 1994, Kara Hultgreen, the first woman to qualify as a carrier-based F-14A pilot, was killed when one engine on her F-14 suffered a compressor stall on final approach to the USS Abraham Lincoln (CVN-72), and the aircraft inverted. [ [http://www.navy.mil/navydata/navy_legacy_hr.asp?id=69 US Navy Constellation page] ] [NY Times, March 1, 1995]

The F-14's problems did not afflict TF30 engines in the F-111 to nearly the same extent, because that airplane was used as a strike aircraft. This type of mission is characterized by discrete phases; the pilot changes throttle settings for each phase and otherwise leaves the engines alone. Though the F-14A entered service with the Navy powered by Pratt & Whitney TF30, by the end of the decade, following numerous problems with the original engine, the Department of Defense began procuring F110-GE-400 engines and installed them in the F-14A Plus (later redesignated to F-14B in 1991), which entered service with the fleet in 1988. These engines solved the reliability problems and provided nearly 30% more thrust. Although thrust specific fuel economy was reported as improved during operational testing, overall fuel economy was essentially unchanged from the TF30 during fleet operations.Fact|date=February 2007 The F-14B and D were equipped with more powerful F110-GE-400 engines achieving better than a 1:1 thrust to weight ratio. The F-15 Eagle waited until the development of the F100 turbofan which gave it a 1:1 T/W. The TF30 is not considered to be a high-bypass turbofan.

References

External links

* [http://www.pw.utc.com/vgn-ext-templating/v/index.jsp?vgnextoid=8faaf3b8f77fb010VgnVCM1000000881000aRCRD Pratt & Whitney TF30 historical page]
* [http://select.nytimes.com/gst/abstract.html?res=F60616F63E540C728CDDAA0894DD494D81 "Navy Faults Engine in Female Pilot's Crash", NY Times March 1, 1995]