Talk:Rolls-Royce LiftSystem

Supersonic

F135/F136-engines are currently (and for the foreseeable future) linked to the F35 and thus the F35B and RRLS. As the supercuising F119 is mentioned in the article as the predecessor, it should be noted here that aircraft with RRLS are not able to supercuise but must use afterburner to go supersonic, since it is important to performance capabilities.TGCP (talk) 20:34, 11 January 2010 (UTC)

Fine, add it with the reference, no problem and quite pleased to see constructive additions. Cheers Nimbus (Cumulus nimbus floats by) 21:39, 11 January 2010 (UTC)

I disagree. The LiftFan isn't part of the engine itself,and is not used in supersonic flight. Given that this editor has already added the same blurb, based on a 5-year-old FAQ, to the F-35, F135,a nd F136 articels, we really don't need it here too. - BilCat (talk) 03:38, 12 January 2010 (UTC)

Fueldraulics - really such a new concept or term?

Particularly noting the R-R involvement, is fueldraulics really either novel, or a new word for this? Didn't we first see this with Concorde?

I'm also assuming that (like Concorde) one of the main reasons for doing it this way is less about weight and more about heat soaking of the hydraulic fluid. Rather than having to cool the fluid after use, a fueldraulic system can simply dispose of it through the engine. Andy Dingley (talk) 14:43, 9 August 2012 (UTC)

Diagram of turbojet energy

No source is given for the numbers in File:JetEngineGraph-LiftFan.PNG. Like any un-sourced contribution, this image may be removed if no source can be provided. - Crosbie 12:02, 24 November 2013 (UTC)

I think the numbers were in the source given which has now gone deadlink. I'll try to find them again. TGCP (talk) 12:12, 24 November 2013 (UTC)

Ah, here it is, presented in 1997. TGCP (talk) 12:22, 24 November 2013 (UTC)

Thanks. I note that the caption states 'Diagram of turbojet energy for LiftSystem' when the F135 is a turbofan engine. - Crosbie 12:32, 24 November 2013 (UTC)

They are integrated. When the LiftSystem is engaged, the F135 turns into a turbojet, not a turbofan - unless you count the LiftFan as the fan in turbofan, which it sort-of is. That's what is new and efficient about the entire system. TGCP (talk) 12:38, 24 November 2013 (UTC)

deleted confused statement

"Owing to the significant increase in LP turbine expansion ratio, implied by the large power off-take, the exhaust of the turbofan is switched from a mixed to unmixed configuration." Patent, cited elsewhere, discredits this explanation.Pieter1963 (talk) 23:01, 30 January 2015 (UTC)

change power to thrust

This lift system owes its very existence to not having to increase the power required to hover over that required for horizontal flight. See patent cited elsewhere or "Genesis of the F-35 Joint Strike Fighter" P. Bevilaqua.Pieter1963 (talk) 23:56, 30 January 2015 (UTC)

citation required

"The clutch mechanism, which uses dry plate carbon–carbon technology originally derived from aircraft brakes, needs the ability to transfer 29,000 shaft horsepower (22,000 kW) without chatter or wear while ensuring high life."

Statement might suggest 29,000hp is absorbed during engagement or transferred by friction surfaces after speeds match. Replaced with clarifying statement with cite. The chatter/wear/high life requirements are standard design goals for any clutch I would think, so don't need stating.Pieter1963 (talk) 20:41, 7 February 2015 (UTC)

reversion of my edit by Andy Dingley

Andy, the original contributor's words, the ones re-instated, refer specifically to the cold nozzles. My edit didn't change this focus. I only replaced poorly worded "nozzles on the fan" with equivalent but more professional wording. I hope you will reconsider your edit. CheersPieter1963 (talk) 21:36, 7 February 2015 (UTC)

Reword it if you like (the Liftsystem is certainly different to the Pegasus) but don't imply that the Pegasus nozzles are purely on the bypass flow.

Also this article claims precedence here for lift by mechanically driven fans, which ignores Wibault's work back in the '50s. Andy Dingley (talk) 22:07, 7 February 2015 (UTC)

The original contributor says "on the engine fan like the Harrier". "On the engine fan" is specific to the front nozzles (he's not including the exhaust nozzles, they are not "on the fan"). He mentions this in the same breath as lift fan, which is also ahead of cg, and lift engines, which on the only other operational VTOL YAK-38 were ahead of cg, ie all arrangements for lift ahead of cg.

The second part of the sentence refers to what's done with the engine exhaust, ie lift behind the cg (Pegasus similar so he didn't mention). We don't need to change that. Pieter1963 (talk) 22:25, 11 February 2015 (UTC)