F135 STOVL Testing: The Heat Is On

The relentless march of the Pratt & Whitney F135 short takeoff/vertical landing (STOVL) variant towards government certification in the form of an Initial Service Release (ISR) edged even closer to reality this month with the successful completion of a grueling high temperature margin test.

At Tennessee’s Arnold Engine Development Center, the F135 was intentionally run to generate turbine temperatures in excess of design conditions, while simultaneously powering the turbo-machinery at or above 100 percent. This test, which went far beyond normal operational flight, not only demonstrated the durability of the F135, but also showed it could exceed the thrust specification by a remarkable 34 percent.

The same F135 STOVL engine, designated FX642 and still in excellent condition, will now complete STOVL performance qualification testing at P&W’s West Palm Beach facility, in preparation for ISR certification. Once this occurs later this year, the STOVL F135 will join its sibling, the Conventional Takeoff and Landing (CTOL) / Carrier Variant (CV) engine (which earned ISR in February 2010), as the only government-certified F-35 powerplants available now and for the foreseeable future, especially given current challenges facing the F136 extra engine team.

Congressional incumbents and would-be members alike should pause from their relentless last-minute campaigning to recognize that cancellation of F136 funding is the perfect way to demonstrate that fiscal prudence is more than a slogan. Saying no to GE’s latest “moving target” request for yet another billion dollars to waste on the trouble-prone F136 is the right thing to do, especially when the true figure is probably closer to three times that amount. Here are five reasons.

First, killing the F136 would show voters that it really is possible to slow deficit spending in the face of a potentially crippling national debt that certainly wouldn’t be helped by an extra wasted $2.9 billion.

Second, it would validate the Contractor Furnished Equipment competition that saw both Joint Strike Fighter finalists (Lockheed Martin and Boeing) choose the F135 over the F136 with government approval.

Third, it would reward the fifth generation F135 for nearly 20,000 test hours, thanks in part to the engine’s proven F119 heritage on the F-22.

Fourth, the F135 has already made a smooth transition from testing, bolstering future American and allied defense capability with production engines already being installed and powered up in production F-35 airframes. 

Last and certainly not least, eliminating the F136 in favor of the F135 will ensure thousands of vital aerospace jobs remain here in the United States, rather than being exported to the United Kingdom.

Bottom line: this month’s successful high temperature margin test and other milestones demonstrate that only one F-35 propulsion system – Pratt & Whitney’s F135 – can really take the heat.

– EagleBlogger