Lockheed Martin F-35A, B, C and other ideas

[PR19_Kit]

I just wrote a LONG reply to Caveman's and Hobbe's posts and the site lost the whole darn lot, grrrrrrrrrr. 

It's too darn late to re-write the whole lot now, it'll have to wait till tomorrow.

[Leading Observer]

Where does the Yak-141 fit intothis equation?

[Martin H]

simple. Lockheed bought the lift fan tech off Yakolev.

[Taiidantomcat]

simple. Lockheed bought the lift fan tech off Yakolev.

The Yak-141 doesn't use a lift fan  



Separate engines. No lift fan or clutch or anything.

[rickshaw]

Less "parasitic" weight with a liftfan.  However, the technology is new so riskier.  Potentially more reliable though, than a lift engine.  If the lift engine goes, you have to eject, no matter how healthy your main engine is.  If the liftfan goes you still have to eject but at least it means there is something wrong with your main engine.  I wonder, does the F-35 have the same automatic eject as the Yak 36 did (and I assume the Yak 141)?

[pyro-manic]

I just wrote a LONG reply to Caveman's and Hobbe's posts and the site lost the whole darn lot, grrrrrrrrrr. 

It's too darn late to re-write the whole lot now, it'll have to wait till tomorrow.

If you get that, just press the "back" button on your browser. You'll find that the text will still be there!

[PR19_Kit]

I just wrote a LONG reply to Caveman's and Hobbe's posts and the site lost the whole darn lot, grrrrrrrrrr. 

It's too darn late to re-write the whole lot now, it'll have to wait till tomorrow.

If you get that, just press the "back" button on your browser. You'll find that the text will still be there!

I did, and it wasn't. 

Sometimes that seems to work, but this time it failed miserably. 

[PR19_Kit]

Trying to re-iterate what was trying to say yesterday :-

Caveman,

The Yak-43 and -141 both have, or would have had if they'd have actually built the -43, an less complex control system than the F-35. Because they have two lift engines forward these can be throttled separately from the main engine and can thus produce a pitch input for the airframe. The F-35 has to use its tricky 'lift fan throttle' thing to match the vertical component of the main engine nozzle. See below about that too.

Hobbes,

The Wiki page on the LiftFan actually says the diagram is a turbojet, but you don't get the whole detail unless you open the drawing up full size.

The Space.com link differs in its description of the LiftFan throttle in that it says the throttling takes place in the 'Variable Area Vane box Nozzle' underneath the fan, whereas the Wiki page says the LiftFan is throttled by the intake door. Who is to say which is correct until we get firmer information? I'm inclined to go with the VAVN statement as the intake door is very rarely seen in any other position than fully open at around 30-45 deg or totally closed.

The second link would seem to be a CV entry for Paul Bevilaqua, as it attributes the entire design and technology of the aircraft AND the engine to him! A real 'One Man Band' of an aircraft designer obviously.........

The article manages NOT to mention Pratt & Whitney at all and Rolls-Royce only once in its entire length so I'm inclined to think of it as a PR exercise on Mr Bevilaqua's part rather than a absolute description of how the F-35 actually works.


After watching oodles of minutes of video of the F-35 flying I found some interesting points.


When the F-35 takes off from a flat deck carrier, using some nozzle deflection and presumably some liftfan thrust, it uses a LARGE amount of down elevator as it goes off the deck edge. This would impart a hefty nose-down pitch moment normally but the airframe stays level. That seems to indicate that there's a large nose-UP moment imparted by the main engine/lift fan combination in free air conditions, and they don't apply when the aircraft is over the deck. Quite what's going on I don't know but I'd love to hear what John Farley would say as he watched the vid. Quite how the FAA and RAF pilots will handle then when going off a ski-jump I don't know. Mr Farley could fly a Harrier off a ski-jump hands-off as the ski-jump imparted exactly the same amount of nose-up pitch as the Harrier's engine-wing combination imparted downards!

The F-35 nosewheel retracts forward VERY quickly, followed somewhat more slowly by the main gears. Where have I seen that before? Ah, yes, ANOTHER aicraft called 'Lightning', but that one had two engines, one above the other..... 

When getting ready for a vertical or short landing two big doors open up below the main engine nozzle to enable it to translate downwards, and this occurs at the same time as the liftfan upper and lower doors open, as well as the auxiliary intake doors aft of the liftfan. The main engine nozzle still remains in its full aft position however and doesn't start to translate until quite late in the proceedings. What we can't see is when the liftfan starts to run, that would be very interesting but it would need vid shot from above and forward of the aircraft.

All in all it's a fascinating piece of technology no matter how it works!

[Hobbes]

simple. Lockheed bought the lift fan tech off Yakolev.

They definitely had a deal with Yakovlev, but not the lift fan as Taiidan said. IIRC the swivel mechanism for the main nozzle was a Yak design.

[Martin H]

Could have sworn it was the lift fan.  but now you mention the nozzle, it does have a fairly similar look to the 141 nozzle

[PR19_Kit]

Could have sworn it was the lift fan.  but now you mention the nozzle, it does have a fairly similar look to the 141 nozzle

AFAIK Rolls-Royce first came up with the liftfan idea, despite what 'Mr. I designed the entire F-35 on my own Bevilaqua' would have us believe....

[kitnut617]

I think you'll find that the BAe P.1216 was designed with the hot rear exhaust nozzle very similar to the F-35's (at least from various drawings that are around that's what it looks like), all I'm not sure of is the timeline if you compare when it was designed and when the Yak.141 was.  Now as Martin has produced a P.1216 I wonder where he got his info from, I'm sure it would have something on the hot rear nozzle.

[jcf]

Could have sworn it was the lift fan.  but now you mention the nozzle, it does have a fairly similar look to the 141 nozzle

AFAIK Rolls-Royce first came up with the liftfan idea, despite what 'Mr. I designed the entire F-35 on my own Bevilaqua' would have us believe....

Nope, on the patent Bevilaqua and Shumpert are the inventors and Lockheed-Martin the assignee,
Rolls-Royce were brought in by L-M and P & W to turn the idea into hardware.

http://www.google.com/patents/US5209428.pdf

Also I don't see anywhere in the Wiki entry on the LiftSystem that the Harrier is dissed nor do I read the piece
on Bevilaqua as him claiming to have designed the 'entire F-35'. Which at any rate is an article from Design
News on their 2004 Engineer of the Year, and not written by the subject. The biggest error on the
Wiki page is where it talks about the engine having 'turbo-fan' and 'turbo-jet' modes rather than 'turbo-fan'
and 'turbo-shaft' modes, as it operates in the latter mode while driving the fan.

BTW as to who 'did it first', if you are speaking of the first vectored-thrust flat-riser VTOL, then that
is the Bell X-14, not the P.1127.

[PR19_Kit]

Nope, on the patent Bevilaqua and Shumpert are the inventors and Lockheed-Martin the assignee,
Rolls-Royce were brought in by L-M and P & W to turn the idea into hardware.

http://www.google.com/patents/US5209428.pdf

R-R were working on the idea before that 1994 patent, even if they omitted to patent it. I installed their first friction welder in 1992 IIRC and it was their clear intention at the time to use the technology to build big fans with it. Two bodies coming up with a similarly elegant  idea at the same time, although for different purposes perhaps?

Also I don't see anywhere in the Wiki entry on the LiftSystem that the Harrier is dissed nor do I read the piece
on Bevilaqua as him claiming to have designed the 'entire F-35'. Which at any rate is an article from Design
News on their 2004 Engineer of the Year, and not written by the subject. The biggest error on the
Wiki page is where it talks about the engine having 'turbo-fan' and 'turbo-jet' modes rather than 'turbo-fan'
and 'turbo-shaft' modes, as it operates in the latter mode while driving the fan.

BTW as to who 'did it first', if you are speaking of the first vectored-thrust flat-riser VTOL, then that
is the Bell X-14, not the P.1127.

It's the general tone of the Wiki piece that I was commenting on. The 'F-35 is the best thing since sliced bread and outperforms that old Harrier idea' tone. Of course it does, it's almost 2013 now and the Harrier was in operational service in 1969.

IIRC the X-14 wasn't exactly the fastest kid on the block and the vectored thrust technology it used wasn't really usable in a combat aircraft, whereas the P.1127's certainly was.

It'd still be good to have a definative article on how the F-35 propulsion and control systems work, rather than PR items written by people who have their own axe to grind.

[Hobbes]

R-R were working on the idea before that 1994 patent, even if they omitted to patent it. I installed their first friction welder in 1992 IIRC and it was their clear intention at the time to use the technology to build big fans with it. Two bodies coming up with a similarly elegant  idea at the same time, although for different purposes perhaps?

RR have been using the friction welder for fan stages in other engines as well (e.g. the RR Trent), it's possible that the friction welder installation predates the lift fan idea.