F-35B UK SRVL info - Updated when new/old info available

[quicksilver]

There will be a limit for gusting cross winds for a VL, which I gather the ship can adjust by a heading/speed change to get under whatever crosswind wind limit. A quick 'hover taxi' just outboard may be in order - if it is allowable. All pilot accounts stress how easy it is to fly the F-35B in STOVL mode making all kinds of adjustments possible during a difficult condition VL.

Before they "C" the jets, the LSO will have talked to the Air Boss and the Air Boss will have talked to the bridge to put the recovery winds inside the wind star. Depending on the experience and general competence of the pilots, and the needs of the ship (a range of navigation, position or formation considerations) those winds may be heart of the wind envelope or they may be edge of the wind envelope. Because STOVL jets can also do cross-axial and bow-to-stern approaches sometimes the ship just maintains what it's already doing and the pilot and the LSO make the adjustment by using one of those patterns.

However, it is *extremely* rare for STOVL pilots to take their own wave off simply because they overshot the spot, the reason being it's generally a bad idea. There is no air taxiing -- one just adjusts ones speed relative to the ships motion until one is abeam the intended point of landing and the LSO give one the 'cleared to cross.' Pretty simple stuff, even in Harrier.

[spazsinbad]

Agree.

[quicksilver]

And a link to Harriers doing bow-to-stern recoveries during Libya ops.

http://www.youtube.com/watch?v=f5f8MsZiI2k

[spazsinbad]

Great video. I have read somewhere some time ago that SHARs or RAF Harriers used to park themselves on deck after landing by taxiing backwards a bit (not air taxi - this idea came from a former SHAR pilot saying it was a possibility in an emergency to get to a clear deck spot rather than intended becoming foul by accident). I'll look again for a Harrier 'wind star/rose'. Could not find one earlier but there are lots of helo specific ones in flat deck NATOPS.

[quicksilver]

Great video. I have read somewhere some time ago that SHARs or RAF Harriers used to park themselves on deck after landing by taxiing backwards a bit (not air taxi - this idea came from a former SHAR pilot saying it was a possibility in an emergency to get to a clear deck spot rather than intended becoming foul by accident)...

True. Nozzles to the braking stop (nominally, 98.5 degrees which is ~17 deg fwd of the hover position, 81 deg).

[spazsinbad]

Well, Well, Well... Allo, Allo, Allo - what have we here...

JSF programme to proceed with UK-specific land-based carrier trials Gareth Jennings 09 Jul 2012

http://www.janes.com/events/exhibitions ... oceed.aspx

"The Program Office for the Lockheed Martin F-35 Lightning II Joint Strike Fighter (JSF) is to shortly commence UK-specific trials for carrier operations of the short take-off/vertical landing (STOVL) variant F-35B, it was announced at the Farnborough Airshow 2012.

Speaking on 10 July, BAE Systems lead STOVL test pilot Peter 'Wizzer' Wilson said that 'ski-jump' launch trials will begin at Naval Air Station (NAS) Patuxent River, Maryland, in the near future, while work on the shipborne rolling vertical landing (SRVL) is also ongoing.

"A 'ski jump' is in place at Pax River that is based on the one [formerly fitted to HMS] Illustrious," he said, adding: "If we can get a few launches in over the next 12 months or so to help de-risk the programme, that would be something that [the UK Ministry of Defence (MoD)] would be interested in."

Wilson said the advantage of the 'ski jump' launch method is in the extra time it gives the pilot on take-off. "The real benefit is one of timing. Once airborne you are flying upwards rather than horizontal, and this gives you extra time to think if something should go wrong," he explained.

In addition, Wilson noted that the 'ski jump' saves approximately 100 to 150 ft of deck run over the standard 'flat top' carrier deck.

"Everything we have seen in modelling is that [the 'ski jump'] is the best way to get this aircraft airborne," he said.

Wilson noted that the lift-fan door behind the cockpit does not affect the aircraft's handling when open for the landing and take-off phases of flight.

"There are no issues in terms of drag," he said. "We can open [the door] up to speeds of 250 kt and you don't feel a thing in the cockpit."

With regard the SVRL landing technique, which is designed to increase the aircraft's fuel and/or weapons bring bag capacity, Wilson said that the Program Office is continuing the support the UK-specific work in this field, although he added that the UK government has not yet decided if it will adopt this technique on the two Queen Elizabeth-class ships (CVF) when they enter service...." [Fahgedaboutit]

[fiskerwad]

Wilson noted that the lift-fan door behind the cockpit does not affect the aircraft's handling when open for the landing and take-off phases of flight.

"There are no issues in terms of drag," he said. "We can open [the door] up to speeds of 250 kt and you don't feel a thing in the cockpit."

This part still just amazes me.
fisk

[archeman]

Wilson noted that the lift-fan door behind the cockpit does not affect the aircraft's handling when open for the landing and take-off phases of flight.

"There are no issues in terms of drag," he said. "We can open [the door] up to speeds of 250 kt and you don't feel a thing in the cockpit."

This part still just amazes me.
fisk

I wonder if that is because the fan is reducing the air pressure buildup that you would expect just in front of the door?
Even if the fan is reducing the effects the wind gusts at 250kt, those gusts would not be constant but the pressure pull from fan would be nearly constant.
So I'm not sure how the pilot couldn't feel the pressure difference hitting the aircraft surfaces.

[quicksilver]

Wilson noted that the lift-fan door behind the cockpit does not affect the aircraft's handling when open for the landing and take-off phases of flight.

"There are no issues in terms of drag," he said. "We can open [the door] up to speeds of 250 kt and you don't feel a thing in the cockpit."

This part still just amazes me.
fisk

I wonder if that is because the fan is reducing the air pressure buildup that you would expect just in front of the door?
Even if the fan is reducing the effects the wind gusts at 250kt, those gusts would not be constant but the pressure pull from fan would be nearly constant.
So I'm not sure how the pilot couldn't feel the pressure difference hitting the aircraft surfaces.

The door opens to a lower angle at higher airspeeds within the Mode 4 envelope.

The lift fan 'pull,' as you call, it is not constant -- it varies pressure recovery (through VIGVs) in order to balance lift between its own output and the main engine.

[spazsinbad]

Some details which may change or have changed via subsequent testing or door hinge changes etc....

F-35 Begins Year With Test Objectives Unmet [STOVL IAS Change] Jan 4, 2011 By Graham Warwick

http://www.aviationweek.com/aw/generic/ ... 279507.xml
-
“...unreliable upper lift-fan door actuator redesigned, and no problems were experienced in the last quarter, he says. Vertical landings, halted since September after the discovery of wear on auxiliary inlet-door hinges, are set to resume this month. McFarlan says some hinge components have been redesigned & operation of the lift-fan door rescheduled to reduce airloads on the auxiliary doors during semi-jet-borne flight.

The lift-fan door was programmed to open to 65 deg. below 120 kt., and to 35 deg. above that airspeed. But with the large door fully open, loads on the auxiliary-inlet doors behind it are reduced, so the schedule has been changed to keep the lift-fan door open 65 deg. up to 165 kt. during a short takeoff, he says.
_____________

F-35B - Doors (Pt. 2) by Graham Warwick Dec/9/2011

http://www.aviationweek.com/aw/blogs/av ... 17-3364-4f
bf-a9dd-4feda680ec9c&plckPostId=Blog%3aa68cb417-3364-4fbf-a9dd-4feda680ec9cPost%3a41e6d676-ad38-4c26-a670-b72068fabeae&plckScript=blogScript&plckElementId=blogDest

“Dorsal auxiliary air-inlet doors, which open in STOVL mode to increase mass flow into the engine & generate an additional 7,000lb of vertical thrust, were found to flutter in semi-jetborne flight, causing premature hinge wear.

The initial fix was to modify operation of the large lift-fan door forward of the auxiliary inlet to stay fully open to higher airspeed on short take-offs to ‘shelter’ the clamshell doors. Instead of closing to the 35° mid position at 125kt the aft-hinged lift-fan door now stays fully open at 65° to 170kt on take-off, & begins to open to 65° at 160kt on approach to landing.”
_____________

F-35 Flight Testing At Pax [excerpt] By Eric Hehs 15 October 2012

http://www.codeonemagazine.com/f35_arti ... tem_id=110

"...The test team at Pax is also exploring the maximum speed end of the STOVL portion of the flight envelope, which is 250 knots. “The buffet and noise is significant when we have the upper lift fan door all the way open, which is an angle of sixty-five degrees, at that speed,” Faidley said.... [Looks like during STOVL transition from wing-borne flight the Lift Fan door will open only to 35 degrees then full 65 degrees from 160-5 KIAS...]

...Some of the flight test aircraft have special software that allows the pilot to override the standard control laws that actuate the various doors and nozzle angles. The flight control laws for the STOVL variant have six modes that are associated with specific actuations. Mode 1 defines conventional flight. Mode 4 defines STOVL. The other four modes define transitional states between the two primary modes. “If a pilot loses a hydraulic system in Mode 2, we know that the doors associated with STOVL flight will be positioned a certain way,” Faidley explained. “We are seeing how well the airplane flies in those conditions.”...”

...[Dan Levin LM Test Pilot Pax] STOVL operations are simple and intuitive. The flight control system is automated in the right ways. The pilot doesn’t even notice the transition between conventional flight and STOVL mode.”..."

[cerberus]

So have the UK decided on the B now, because there was some talk of them getting the C a while back.

[spazsinbad]

Short answer is yes (to what though). Long answer may be found here: http://www.f-16.net/f-16_forum_viewtopic-t-15969.html

I have a question - if you are from York - I forgot the question.

[madrat]

We used to have these toys while growing up that used little flashlight shaped fans to hold ping pong balls in the air. Its a shame the isn't some high tech way to use a similar concept to retrieve F-35B fully loaded.

[cerberus]

I'm starting to lose faith in the F-35B. It might be okay for use by the army in short range ops with a low fuel load and few weapons but other than that I don't see the point. It's not VTOL and if it isn't VTOL, what's the point? STOVL has the complication of retrieving fully loaded aircraft and to operate from unprepared surfaces, an aircraft is either VTOL and can, or it can't. There is no 'STOVL'. Then you have the smaller internal bay issue.

I only see a use for the A and C until the engine gains an extra 8-10,000lbf to make it a proper VTOL like the Harrier.

[count_to_10]

We used to have these toys while growing up that used little flashlight shaped fans to hold ping pong balls in the air. Its a shame the isn't some high tech way to use a similar concept to retrieve F-35B fully loaded.

An F-35 is going to have a minimum speed at which it can maintain flight at any given load. The heavier that load, the faster it has to go.
So, the main difficulty of any recovery mechanism that attempts to increase that landing load is how to provide support while the aircraft is slowing down from that speed, and that means it will have to move with the aircraft relative to the landing platform for that stopping distance.