Forum: F-35 Engine

After all the chat about the advantages thrust vectoring would add to the Viper, it looks to me that the F-35 will not have TV (not including the swivel nozzle for the STOVL engine). Am I wrong on this, and if not why?

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1 - weight
2 - cost
3 - mission doesn't require it

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

A TV nozzle weighs ALOT. I believe the new F119 for the Raptor tips the scales at over 5000lbs!?

I'm not sure how much the TV nozzle for the F100 or F110 weighed but it didn't give the Viper enough gain in performance to ofset the cost of the project.

Even if it did make cool flips and an awesome show on the trim-pad. Very Happy

The base F119 engine is below its weight specification, the 2D vectoring nozzle is I understand above its weight specification. This shifts CoG aft, and probably resulted in a minor reworking of the rear end mountings for increased strength for maneuvering flight. It's a big engine, the prototype engines sucked 270 lbs mass airflow per second, the production engines were uprated with 15% more airflow, so that would be around 310 lbs of air a second. Coupled with the low bypass ratio and a specific thrust of around 82 lbs thrust/lbs airflow you get a massive amount of dry thrust. The F135 engine has even more airflow but operates at a similar temperature so the specific thrust (and actual thrust) seems to be a bit lower. I have a pic of the F-35 propulsion system and it has weights and other specifications......if I can figure out how to attach pics to my posts. My first post here btw, hiya to you all.

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

Wonder how hot that clutch gets when taking up all the horsepower from the main engine!?

Or how many engagements the lift-fan power-train will last between replacements/overhauls?

Shocked

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

Hate to double post, but I did some surfing after the post above and found some AWESOME facts. Such as:

"The Rolls-Royce LiftSystem®, using energy provided by the aircraft’s single main engine, provides what for so long has proved unachievable: vertical lift and supersonic capability in one package. It attains this unmatched ability by assisting the extraction of some 40,000 lbf of vertical thrust from the conventional main engine, which can produce only 30,000 lbf of horizontal thrust in its normal mode. This remarkable feat is achieved by the use of a separate, mechanically driven vertical fan that is powered by the LP turbine of the prime engine. The extra mechanical power is made available by opening up the final nozzle on the main engine at the same time as directing its efflux vertically by means of the Rolls-Royce 3 Bearing Swivel Module. The system thus effectively increases the bypass ratio of the main engine through the induction of higher airflow by the LiftFan with not only higher airflow, but higher airflow with the ideal characteristics for vertical flight (high mass flow and low jet velocity). This is truly a revolutionary step that redefines the relationship between horizontal thrust and vertical lift, and produces significant increases in performance, efficiency and safety ...................... a clutch mechanism with the ability to transfer 29,000 shaft horsepower without chatter or wear while ensuring high life...." from "GOING VERTICAL"- JOHN HUTCHINSON - FREELANCE WRITER - TECHNOLOGY AND INNOVATION

Very interesting [Link pending approval] (at least for an engine tech?)

Complete file located here: [Link pending approval]

In a seperate page I found that the clutch/drive-train was tested to 1,500 engagements to demonstrate it's required life [Link pending approval] bad for absorbing 29,000 HP at each engagement!? Shocked

The picture I posted is a screenshot from a US Government webpage detailing turbine technology development over the past 60 years, the 40000 vertical thrust is correct, the dry thrust of the F135 is 23400 lbs reducing to 15700 at the main nozzle in vertical mode, this is a result of the LiftFan system extracting a lot of energy from the gas stream when activated, plus the energy fed through the roll post system and the inevitable loss as the dual bearing rear nozzle rotates downwards, there will always be loss when you're directing that much energy over such a large vector.

http://www.udri.udayton.edu/vofcc/docum ... tation.pdf

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

Outstanding presentation!

I don't think most people realize how important the engine(s) is(are) to a successful airframe.

I've also seen the $$ figures for engine support for the USAF, the number is [Link pending approval]

A typical JEIM (Jet Engine Intermediate Maintenance) Shop at any given base will typically use more $$ of the budget per year than the rest of the base COMBINED!

Jet Engine Technicians in the USAF also have one of the highest job satisfaction ratings and retention rates in the USAF.

Here's a shot of an F135 on the testbench at Arnold Engineering.

Joined: Feb 01, 2007 - 02:38 AM Posts: 0 Status: Offline

Awesome [Link pending approval]

habu2 said it all, but the main point for me was cost.

Don't forget the main concept of JSF is a low cost flighter, thrust vectoring would blow that concept through the roof. You only have to look at the endless cost of the f-22 thrust vectoring sceme to see how it would blow the budget of any f-35 buyer, even the US.

The JSF is meant to stop the, ''fighter freeball'', with fighters getting more and more high tech less are bought due to cost, and so on. Its well known if current fighter evalution carrys on the US in 2020 will only be able to afford a handful of planes. Its a case of going back to basics and making a war machine and not a high tech machine that needs its own billion $ bank account to run.

Forum: F-35 Engine

F-35 - Thrust Vectoring?