The debate over the duelling engines for the Lockheed Martin F-35 Joint Strike Fighter has triggered a new war of words on the eve of the Paris air show.

The latest sparring centres on Rolls-Royce's claim that cancelling the F136 could deprive JSF of a major upgrade to variable cycle engine technology after 2020.

"Here's an opportunity for GE and Rolls-Royce to take this technology as a team and incorporate it in F136 as part of the Fighter Engine Team on JSF," says Dennis Jarvi, R-R president for North American defence.

Pratt & Whitney counters that it sees no need to incorporate all-new engine technology into the JSF, and the F135's current upgrade roadmap, which includes a 5% thrust boost arriving in 2010, will be sufficient.

"The F-16 began at 24,000lb thrust [106kN] and, for P&W, it [has increased] up to 29,000lb of thrust as the aircraft evolved," Farmer says. "The same will occur with the JSF. P&W has the thrust and performance improvement plans that will accommodate the needs of the JSF."

The F-35's current power requirement is for about 41,000lb thrust. The F135's short-takeoff-and-vertical-landing variant slightly exceeded that level in recent ground tests.

Meanwhile, US lawmakers have moved to rescue the F136 in the fiscal year 2010 budget. For the fourth year in a row, the Department of Defense omitted funds to continue F136 development. But Congress has refused to accept the DoD's argument about cost-savings, and backed the programme to reduce operational risk of dependence on one fighter engine.

But R-R's claims about F136 upgrades introduce a new argument in favour of continuing the programme.

In 2007, the AFRL rejected P&W's proposals to compete for the adaptive versatile engine technology (Advent) programme, which aims to produce a variable-cycle system in after 2018.

Instead, the AFRL selected separate proposals from GE and R-R for Advent's phase 1 programme. That means either manufacturer could incorporate Advent upgrades for the F136.

Advent was created to develop engine technology for the next-generation bomber (NGB), but the proposed postponement of that programme has clouded those plans. However, according to R-R, the US Air Force has shifted Advent's focus from NGB to an F-35 engine upgrade which would be timed to coincided with a mid-life update for the airframe.

"I think we do have a first point of entry [for Advent] identified regardless of what happens with NGB, and that is JSF," Jarvi says.

Source: Flight Daily News