Forum: General F-35 Forum

There is not practical restriction on hover height. During one sales tour (G-VTOL two seater) we operated out of Quito for a week. The runways were about 9,200 feet altitude with ambient temperatures about 75 degrees F.

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I would think the general rule for hovering a helicopter would apply here: make sure you have either a) enough airapeed to enable a glide from any particular altitude you're at, or b) enough altitude to translate it into airspeed should the engine fail for any reason. There is an area of altitude/airspeed combinations that helo pilots are loath to operate in because if something happens and the engine quits, they will likely crash. Too low to autorotate without losing rotor RPM, and too slow to transform airspeed into altitude. Seems to me the same thing would apply to the F-35B.

viper1234 wrote:

This is really not so much a question for tactics, but rather basing options and access to austere locations at high altitudes. Bagram is at nearly 5000' and I'm sure there are other places the Marines might go that are even higher.

By the way there is no doppler notch for a ground radar... so that tactic is N/A. I suppose you could get away with it versus fighter aircraft, but why shorten your missile range when your opponent can't detect you anyhow? I'm sure Hollywood will have plenty more fun with it in the future. Stand by for a Top Gun 2 that will do for the Marines what Iron Eagle 1 - X did for the AF... how unfortunate.

Iron Eagle- one of the few movies that were such steaming piles that I walked out of them to stop the torture. ("Teen Wolf" was another.)

That_Engine_Guy wrote:

I wonder if the Harrier's VIFF (Vector In Forward Flight) trick would work... Would depend on the MAX speed to engage the lift-fan. Hate to rip that huge door off... I think they should have stuck with 2 side doors?

The VIFF maneuver in the Harrier moves the thrust vector relative to the center of lift, this in turn allows a tighter turn at the same bank angle.

The downside of it is that you can lose speed really fast, as you come out you are low on the energy level and have to either accelerate in a straight line, not recommended, or go into something like a rolling scissors to build up airspeed again.

The good thing about it is that if it is done properly you can out turn just about anything out there. I do not think that the F-35 lift system will provide the same advantage however other ones will surely surface.

A little bit of history about the VIFF maneuver, it was initially developed by Harry Blot and Bud Baker, when the stress engineers ran the numbers on the instantaneous pressure change in the reaction control ducts they were ready to pin them both to the drawing board with sharpened slide rules.

espenjoh wrote:

Anyone that can say something about how high a F-35b can be in a hover? For instance could an F-35 hover in 10.000 feet, acting like a helicopter for a minute ore two?

According to the LM F-35 Environmental Description Document, the maximum design altitude for hover operation is 10,000 feet. Maximum hover duration is 2.5 minutes at a minimum practical height above ground effects and FOD hazard (typically 60-70 feet).

SixerViper wrote:

I would think the general rule for hovering a helicopter would apply here: make sure you have either a) enough airspeed to enable a glide from any particular altitude you're at, or b) enough altitude to translate it into airspeed should the engine fail for any reason. There is an area of altitude/airspeed combinations that helo pilots are loath to operate in because if something happens and the engine quits, they will likely crash. Too low to autorotate without losing rotor RPM, and too slow to transform airspeed into altitude. Seems to me the same thing would apply to the F-35B.

Other than the fact that it certainly operates better IGE than OGE I cant imagine it being very similar to hovering a Helicopter. If his engine quits at an OGE hover he's probably gonna die, in a whirly bird I just drop the collective out to keep from bleeding rotor and cushion when the trees start getting bigger. If he loses his engine IGE he just hits the ground maybe a little softer (depending on height) and more than likely walks away from a F*****up Aircraft, in a fling winger IGE I just pull pitch and bleed my rotor in favor of lift. I would say his version of the dead mans curve for a helo is more like a dead mans box. As to how high others on here are much more qualified to speak to that as his hover is based on thrust not lift. But I am pretty certain that as long as he's greater that 1 to 1 the trees keep getting smaller.

pete

msupepper wrote:

espenjoh wrote:

Anyone that can say something about how high a F-35b can be in a hover? For instance could an F-35 hover in 10.000 feet, acting like a helicopter for a minute ore two?

According to the LM F-35 Environmental Description Document, the maximum design altitude for hover operation is 10,000 feet. Maximum hover duration is 2.5 minutes at a minimum practical height above ground effects and FOD hazard (typically 60-70 feet).

This is effectively the same as the AV8B Harrier, probably based on the same specification.

Elite 1K Joined: May 26, 2005 - 08:39 PM Posts: 1496

sweetpete wrote:

If his engine quits at an OGE hover he's probably gonna die

Although really, if he's out of ground effect, he'll probably decide to chuck the jet before he gets killed.

Guysmiley wrote:

sweetpete wrote:

If his engine quits at an OGE hover he's probably gonna die

Although really, if he's out of ground effect, he'll probably decide to chuck the jet before he gets killed.

Good point, the little yellow handle is a feature I forgot to ask for in my model.

sweetpete wrote:

Guysmiley wrote:

sweetpete wrote:

If his engine quits at an OGE hover he's probably gonna die

Although really, if he's out of ground effect, he'll probably decide to chuck the jet before he gets killed.

Good point, the little yellow handle is a feature I forgot to ask for in my model.

You forgot the cast iron guarantee, if you are unhappy with the performance of the seat, you can discuss it in person when you receive your tie.

Rather weird story from AV8A days at Cherry Point. We had a pilot come into the hover in and the stability system failed so that he got into a high sideslip yaw coupled roll, pilot did the sensible thing and ejected as the aircraft slowed into the hover, seat worked fine.

Pilot was standing on the ground when the crash truck arrived. Crash crew asked "Where's the crash?" pilot said "not yet" and pointed skyward. The aircraft was in a stable hover at about 60 feet, 15 minutes later it landed (arrived) with some distress on impact to the landing gear and structure. I think the BUNO was 158950.

Forum: General F-35 Forum

F-35 hover, how high?