F-35B

[seabee1526]

http://www.youtube.com/watch_popup?v=Ki86x1WKPmE&feature=colike


Team Navy - Marine Corps looking good.

[The Inspector]

I'll keep my skeptical hat on for now-and continue to wonder just when one of them is going to 'Frisbee' that lift fan.

[Kyleb]

I'll keep my skeptical hat on for now-and continue to wonder just when one of them is going to 'Frisbee' that lift fan.

I expect one to Frisbee a lift fan. Just as the guys who designed/built/flew the F-one oh whatever expected to lose a dozen of 'em working out the worst of the bugs. Leading edge systems, by definition, operate on thinner margins. We're better at it today (more pre-production te$t$, $imulation$, and hurdle$), but things still fail.

[JOHN MILLER]

Do they have the same problem of overheating if left in a hover like the harrier?

[Mike]

Do they have the same problem of overheating if left in a hover like the harrier?

Why would you want to leave one in a hover? Is there any pressing operational reason to do so, other than showing off before an airshow crowd?

[JOHN MILLER]

I watched on military channel and they said when a hariier lands vertical, it must land quickly otherwise risk overheating because no airflow to cool it. Just asking.

[Cvairwerks]

No overheat problems in hover mode. The lift system in the F-35 is considerably different that what the Harrier uses. All of the lift thrust for the Harrier is provided directly by the engine. The F-35 uses a coupled fan to provide about 50% of the lift thrust with the engine bleed air and exhaust providing the rest. Even in the hover mode close to the ground, the ingestiation of engine exhaust is minimal. That ingestation is part of what causes the Harrier to have have hover time limits.

As to doing a frisbe with the lift fan, it would be about the same chance as spinning off the compressor section of any hgh bypass turbofan.....

[The Inspector]

No overheat problems in hover mode. The lift system in the F-35 is considerably different that what the Harrier uses. All of the lift thrust for the Harrier is provided directly by the engine. The F-35 uses a coupled fan to provide about 50% of the lift thrust with the engine bleed air and exhaust providing the rest. Even in the hover mode close to the ground, the ingestiation of engine exhaust is minimal. That ingestation is part of what causes the Harrier to have have hover time limits.

As to doing a frisbe with the lift fan, it would be about the same chance as spinning off the compressor section of any hgh bypass turbofan.....

Ya mean like early versions of the R/R RB-211 on L-1011's?

Don't want to stir things up in the rather interesting discussion of the F-35B, but since this is an airplane that is still in test and has not even entered regular service yet, it doesn't seem to fit the definition of a "warbird" as we discuss in this forum:

"This is the place where the majority of the warbird (aircraft that have survived military service) discussions will take place. Specialized forums may be added in the new future"

Is there another place in WIX, or perhaps should consideration be given to adding a separate sub-forum for discussing newer aircraft that are not yet vintage warbirds that "survived" military service? Just some thoughts.

[Pogmusic]

Seems like they require forward stick when doing a rolling take-off. Sort of counter intuitive.

[Cking]

It looks like a dogs dinner compared to the Harrier/Pegasus combination. I wonder what happens when one of the many actuators that operate one of the many doors, flaps and scoops, fail?

Rgds Cking

[Kyleb]

It looks like a dogs dinner compared to the Harrier/Pegasus combination. I wonder what happens when one of the many actuators that operate one of the many doors, flaps and scoops, fail?

Rgds Cking

Probably about the same thing that hapens when the Harrier has a problem with a puffer jet or one of the rotating nozzles. Vertical lift isn't for the faint of heart.

[Cvairwerks]

It looks like a dogs dinner compared to the Harrier/Pegasus combination. I wonder what happens when one of the many actuators that operate one of the many doors, flaps and scoops, fail?

Rgds Cking

Actually, not much happens....Going from standard flight to hover mode and a failure...no hover mode. Going the other way....no STOVL launch. Either way the crew cheif is going to be a busy beaver for a while.

[Noha307]

Don't want to stir things up in the rather interesting discussion of the F-35B, but since this is an airplane that is still in test and has not even entered regular service yet, it doesn't seem to fit the definition of a "warbird" as we discuss in this forum:

"This is the place where the majority of the warbird (aircraft that have survived military service) discussions will take place. Specialized forums may be added in the new future"

Is there another place in WIX, or perhaps should consideration be given to adding a separate sub-forum for discussing newer aircraft that are not yet vintage warbirds that "survived" military service? Just some thoughts.

Right here is exactly where it should be. To quote the subtitle of this subforum:

This section is for discussion of all things military, past or present, that are not aviation related. Armor, Infantry, Navy stuff all welcome here.

Well, actually, now that I notice, it states "not aviation related". Nevertheless, this still seems a good place for the thread. (And believe me, out of place threads are irritating! )

Do they have the same problem of overheating if left in a hover like the harrier?

No, it doesn't. To quote a book I own:

"Lockheed Martin designers calculated that the lift fan would blow a cushion of cold air under the hovering aircraft, preventing most hot exhaust gases...from reaching the air intakes. ...in hover tests intake temperatures rose just 5°F (3°C)."

What I would like to know is how long the F-35B can hover. IIRC, if the harrier took off and landed vertically it couldn't do it at any other time in that same flight due to high fuel consumption.

EDIT: Please note: I originally found this thread in the Military Matters section, and didn't realize it had been moved there from "the Hangar" until later, hence my confusion as to why I had thought the thread was in the correct place.

Last edited by Noha307 on Sat Dec 29, 2012 3:36 pm, edited 1 time in total.

[Cvairwerks]

Noha: That info isn't available for two reasons.... Max hover time is probably not a priority test point, so it will most likely not be accomplished for some time... Secondly, that limitation would be in the -1 and that document is classified at this time.

Also, max hover time is going to be dependent on stores loaded, fuel on board, local conditions et al. so it will be variable.

The best place to find out stuff on the F-35 that is in the public domain, is to read the forum section on the F-35 over on F-16.net.