Lockheed: Many F-35B landings won’t be vertical

Taking the discussion back to the thread --

Along other stuff, BSIAC said, "Fuel burn is the least of anyone's worries in peacetime." Not so. Whether one is engaged in some real world rodeo or in the local training area, one's position relative to the nearest suitable landing site and how much fuel one is going to use in order to get one's **** safely back to said site is always prominent in ones mind.

"The major benefits for doing conventional landings are in having the ability to bring back more fuel and weaponry than with VL, not to mention reducing wear on the fighter." True as long as one can keep it on the runway. If one happens to have 4K' of runway when 6 is needed, then you may have a problem.

"If one is simply looking at fuel loss alone, then choosing VL will always mean dumping excess fuel." Not necessarily. Depends on how much the jet weighs, how much load it is carrying and how much VL performance the jet has in the given conditions.

"What a conventional landing spends in taxiing to and from the runway really pales in comparison to what is saved overall by not engaging the lift fan." Would have to believe so given that they're taking power off of the main engine to run the lift fan, and aiui the lift fan creates about half of the jet's vertical thrust. (Am sure Spaz has a link to something relevant on this).

Spaz has the 'royal telephone' : http://www.f135engine.com/proven-tech/e ... cter.shtml

Short Take Off and Vertical Landing
STOVL Propulsion System Design

Maximum Thrust (in pounds): 43,000 (191.3 kN)

Short Takeoff Thrust: 38,100 (169.5 kN)

Hover Thrust: 39,400 (175.3 kN)
Main Engine: 15,700
Lift Fan: 20,000
Roll Post: 3,700

Along other stuff, BSIAC said, "Fuel burn is the least of anyone's worries in peacetime." Not so. Whether one is engaged in some real world rodeo or in the local training area, one's position relative to the nearest suitable landing site and how much fuel one is going to use in order to get one's **** safely back to said site is always prominent in ones mind.

I don't get your point. For an aircraft to constantly be so desperate on fuel that they have to weigh the pros and cons of VSTOL/conventional landing... that's just bad management on the part of those who organize these flights. If a fighter is running on fumes by the time it reaches the runway, then the proper thing is to load more fuel for longer legs or in shortening the legs altogether.

"The major benefits for doing conventional landings are in having the ability to bring back more fuel and weaponry than with VL, not to mention reducing wear on the fighter." True as long as one can keep it on the runway. If one happens to have 4K' of runway when 6 is needed, then you may have a problem.

What difference then would it make? If an F-35B can't manage a 4K runway, it certainly as hell isn't going to land vertically. MAYBE they could perform a slow landing, but I'm unsure what their maximum bringback would be.

"If one is simply looking at fuel loss alone, then choosing VL will always mean dumping excess fuel." Not necessarily. Depends on how much the jet weighs, how much load it is carrying and how much VL performance the jet has in the given conditions.

Yes, always. If an F-35B is fully loaded with fuel and weapons, it would have to dump enough fuel so that it could hover. It absolutely CANNOT land in VL with less than a 1:1 ratio. If there were a runway to land on, that very same fighter wouldn't have to jettison anything, as it can land without any weight limitations.

"What a conventional landing spends in taxiing to and from the runway really pales in comparison to what is saved overall by not engaging the lift fan." Would have to believe so given that they're taking power off of the main engine to run the lift fan, and aiui the lift fan creates about half of the jet's vertical thrust. (Am sure Spaz has a link to something relevant on this).

Conventional landings involve powering down the engine as the aircraft slows down, whereas VL's do exactly the opposite. More thrust = more fuel consumption. Less thrust = lower fuel consumption. It can't be any simpler than that.

The problem now becomes measuring the fuel burn for taxiing and comparing it to the fuel burn for those moments when the engine and lift fan are pushed close to their maximum power.

bsag said: "If there were a runway to land on, that very same fighter wouldn't have to jettison anything, as it can land without any weight limitations." This is probably NOT true for any fighter aircraft but of course it depends on what the Maximum Landing Weight is for any type/variation. For carrier landing aircraft it is particularly important so as to not break the arrestor gear/barricade or the aircraft itself via breaking undercarriage.

The F-35 B & C have KPPs for this situation and in the case of the C model an airspeed (Optimum Angle of Attack) limitation for similar reasons described.
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Scorecard: A Case study of the Joint Strike Fighter Program by Geoffrey P. Bowman, LCDR, USN — 2008 April — [PDF 325Kb 'bowman0558.pdf']

https://www.afresearch.org/skins/rims/q ... nginespage

"The capability to operate from a carrier is not as easy as it sounds. Additional weight comes in the form of stronger landing gear, fuselage center barrel strength, arresting hook structure, and additional electrical power requirements. The Navy has added approach speed as a service specific key performance parameter. The threshold for approach speed is 145 knots with 15 knots of wind over the deck. This must be possible at Required Carrier Landing Weight (RCLW). The RCLW is the sum of the aircraft operating weight, the minimum required bringback, and enough fuel for two instrument approaches and a 100nm BINGO profile to arrive at a divert airfield with 1000 pounds of fuel. The minimum required bringback is two 2000 pound air-to-ground weapons and two AIM-120s.

The Navy further requires that the CV JSF be capable of carrier recovery with internal and external stores; the external stations must have 1000 pound capability on the outboard stations & maximum station carriage weight on the inboard."
&
"The USMC has added STOVL performance as a service specific key performance parameter. The requirement is listed as follows: With two 1000# JDAMs and two internal AIM-120s, full expendables, execute a 550 foot (450 UK STOVL) STO from LHA, LHD, and aircraft carriers (sea level, tropical day, 10 kts operational WOD) and with a combat radius of 450 nm (STOVL profile). Also must perform STOVL vertical landing with two 1000# JDAMs and two internal AIM-120s, full expendables, and fuel to fly the STOVL Recovery profile.

The Marine Corps has used the more limiting deck launch, rather than a simple expeditionary airfield, to frame its requirement."
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http://www.hrana.org/documents/PaddlesM ... er2010.pdf

"The F-35C is 51.5 ft long and has a wingspan of 43 ft and 668 ft2 of wing area (7 ft longer wingspan and 208ft2 more wing area than the Air force or Marine versions.) It also carries 19,800 lbs of internal fuel - 1,000 pounds more gas then the Air Force version. It is powered by a Pratt and Whitney F135 engine that produces 28k lbs and 43k lb of thrust in MIL and AB respectively.

The max trap weight will be around 46k lbs, with an empty weight of about 35k lbs.

It will fly an on-speed AOA of 12.3° at 135-140 KCAS [Optimum AofA or Donut]."

bsag, I think you miss the point about fuel. Military pilots monitor fuel usage meticulously. There is no fuel like fuel in your aircraft. Even another tankers fuel may be unavailable due to own or tanker problems, not known until tanking attempt made. Unlikely scenario perhaps but it happens. A jet pilot has a backup plan about fuel (as far as is possible in circumstances) to make the best with what is left as 'quicksilver' suggests. Woe betide any pilot running out of fuel, to eject out of an otherwise good aircraft. Today there will be lots of electronic gizmo reminders about fuel. Yet if these don't work, or are ignored, the pilot is always responsible. It should be possible for an aircraft to lose all fuel indications, yet the pilot return to base, or divert safely, because his mental map and knowledge of fuel usage will allow it.

In the same way if flying a prop trainer aircraft for example then the pilot needs to know where the nearest suitable field is for landing in case of engine failure (if that is possible and of course with no ejection seat). Then there are at least two things on a pilot's mind, fuel and emergency landing field. A jet pilot will have a nearest divert field in mind at all times especially on navigation or strike sorties. And on and on. What is uppermost in a jet pilot's mind is the fuel.

Monitoring / knowing fuel usage is like breathing - an autonomic process that is always in front of jet pilot's mind. For carrier pilots without a tanker in 'blue water ops' (without a divert field) this is extra important. One gets back to the carrier with the maximum amount of fuel that makes the max landing weight/for arrest or anything above the minimum fuel. And yes the USN usually has a tanker, but does the tanker have a tanker? The tanker lands last of course.

A Harrier pilot is used to going to their minimum fuel for landing in the same way an ordinary jet pilot is used to landing with their minimum fuel - and nothing less - where that minimum fuel will allow a last ditch second landing attempt. But otherwise the minimum fuel is an amount that must be there at touchdown or during same. In older aircraft the minimum fuel was extra important due to fuel gauge not being accurate in the landing configuration; so there was uncertainty about the actual amount of fuel onboard. Whatever. The minimum fuel was an amount that was not negotiable but no problem landing at that minimum.

"I don't get your point."

Clearly. Let's leave it at that.

Yes that mantra can be repeated endlessly - but it remains only that - a mantra "no plan to use the ski jump". For a start any capable aircraft can use it. Other visiting STOVL aircraft can use it. It may be used in the future as mentioned. Just because there is no plan today does not mean there will not be a plan in a tomorrow. For example there was no plan to buy the former 'LARGS BAY' and lookee here we have it. There will be plans somewhere about lots of possibilities that may not see the light. But if you are comforted by 'no plan' then by all means repeat it.

Still hoping against hope? Even a spare CVF now? Well why not dream. Plans may change so here's hoping Australia gets 500 JSF's, 30 air tankers, a strategic bomber fleet and a dozen AWD's and an extra 3 brigades for the Army...

All of these are as valid as your argument, when you ignore reason and rely upon the unprovable, unverifiable and rather specious "well anything may happen in the future" point of view.

All of the "changed plans" for ADF over the last decade or more have been in response to a failed or failing capability. Nowhere has a changed plan resulted in an entirely new capability (ie: not a direct replacement for an existing capability) for ADF that I can recall.

In the case of Largs Bay it is the premature, yet still failed capability of Manoora and Kanimbla.

C-17's it was the faliure of the C-130 to adequately support operations far afield.

Super Hornet for F-111. Abrams for Leopards, extra MH-60R's as a replacement for failed Seasprites and the rest as standard replacements for ageing Seahawks and so on.

There is no capability within ADF that might "fail" and require replacement by a literal handful of F-35B's operating from a ship ill-suited (by design) to operating them...

Conan you forgot how the 24 Super Hornet 'spur of the moment about face plan' taking most by surprise. As I have stated more than a few times now on this forum in several threads: Yes there is no current plan to have any Australian F-35Bs on the LHDs. What is tiresome is the belief that 'F-35Bs will not operate from the LHDs'. As I point out of course they will, if only in an effort by the USMC/USA to demonstrate that capability, and to use it as required. And yes who knows what the future may bring.

And I have stated on the very long thread that by reason of explanations given by others (notably GF00012 whomever) that the current RAN LHDs do not have all the gubbins necessary. However for you to state that the Spanish LHDs are "...ill-suited (by design) to operating them..." is ludicrous and you know it. Perhaps you meant the current two RAN versions.

And I'll continue to be surprised by the future and I hope in a good way.

Conan you forgot how the 24 Super Hornet 'spur of the moment about face plan' taking most by surprise. As I have stated more than a few times now on this forum in several threads: Yes there is no current plan to have any Australian F-35Bs on the LHDs. What is tiresome is the belief that 'F-35Bs will not operate from the LHDs'. As I point out of course they will, if only in an effort by the USMC/USA to demonstrate that capability, and to use it as required. And yes who knows what the future may bring.

I didn't forget about the Super Hornets, indeed I mentioned them and it directly confirms my point. Yes plans change, but they change when a capability fails, not because we suddenly have a need to create a massively expensive new capability (as a 3rd LHD or a second CVF and a fleet of naval capable F-35's would be).

The Super Hornets were assessed and planning undertaken by Defence to acquire them nearly 2 years before it even became public that we were going to acquire them.

They weren't a new capability, they were a replacement capability for an intended capability that was failing. That capability was the F/A-18 Hornets, upgraded and equipped wth new standoff weapons and supported by new refuellers which had been chosen to replace the strike capability provided by the F-111's.

This capability was significantly delayed and Government decided this capability wasn't going to meet our air combat requirements, given the increasing capability within our region, the delays with the Hornet upgrades and JSF's, so they added a replacement capability intended to address our failing air combat and strike capabilities.

Again if the point isn't obvious, the Rhinos are a replacement capability, not something completely new and even they aren't on the scale of investment required that you are wishing for.

USMC JSF's landing on the LHD's hardly equals automatic ADF pursuit of such a capability and the Spanish are using their Juan Carlos ship for amphibious warfare first and foremost, any fixed wing operations at sea are for training and quals, not operations. They have a purpose built carrier for that.

I hope I'm wrong, I just don't see the Government stumping up the cash for it. Especially given we have the same political party in power that canned the capability initially in the first place and the others didn't seem to keen on the idea either...

Conan said: "The Super Hornets were assessed and planning undertaken by Defence to acquire them nearly 2 years before it even became public that we were going to acquire them." This would be news to a lot of people. Was not the RAAF hierachy disavowing this plan only weeks/days before it was announced by the then DefMin? I'm not disagreeing with the sudden plan or reasons for the change of plan BTW. It seems - unlike the general public - that you have inside information about these issues at the time?

Again I'll say I'm not disagreeing with the lack of plans to buy/use F-35Bs in Australia at moment. However I'm not ruling it out for future. USMC Harriers or F-35Bs using the LHDs will not be a problem - at least initially - they will be cross decking with both parties wanting to know what needs to be done. No big deal and I'm not making it a big deal about any exploratory cross-decking. I would assume that if the USMC can get aboard the Spanish LHD first then they will go with that for sure. However my point remains we will see STOVL aircraft on the LHDs. Perhaps this will jog an initiative to acquire this capability in the future for future LHDlike flat decks. I'll maintain that at least the Spanish LHD is designed from the outset to operate F-35Bs.

Another recent thread has stated Spanish interest remains. Again no big deal. A flat deck is a flat deck for STOVL aircraft. A Spanish or Australian LHD may not be a primary base for F-35B use but certainly it will be an aid (lily-pad - sea-base) when other aircraft carriers will be their main bases. Aaaah the beauty of a long flat deck (in this case with a ski jump).

The relevance of any political party in Australia (regarding axing of replacement carrier back in early 1090s) escapes me. Surely other factors are more important. I would suggest that the reason the RAN FAA Fixed Wing was axed is a lot more complex than just any specific political party being in power. The Liberals took years dillydallying about a decision for carrier replacement whilst the new Labour Government wanted a quick decision and chose to axe it (to make money available for Hornet purchase & guarantee new Navy ships, as I understand history). One would assume that at that time neither political party wanted the RAN FAA Fixed Wing to continue.

An interesting USN LCDR has written a brief overview of RAN history from end of WWII till after the end of Fixed Wing. The history rings true for me. Download the PDF at:

The Roots & Evolution of the Royal Australian Navy by Richard D. Butler - June 2007

http://edocs.nps.edu/npspubs/scholarly/ ... Butler.pdf

An interesting quote which may have echoes soon when two new LHDs are in use (surplus CVF in a decade perhaps?):

"...The RAN, recognising the growing difficulties associated with its new carrier plan, reverted to the strategy that had saved MELBOURNE during the 1950s. Responding to the cost and threat issues being raised, the Navy decided its new ship [later was to be ex-HMS Invincible] to be rotary wing and short/vertical take off and landing (S/VTOL) capable only. Soon after this announcement, the decision was also made to defer the purchase of the fixed wing aircraft until at least 1983, a logical step for budgetary reasons and also because at the time, the only aircraft available for purchase was the British Sea Harrier....

...In mid-1981, Great Britain determined that HMS Invincible would be designated surplus, and it was promptly offered to the Australian government for $A285 million. Although the INVINCIBLE class had not made the final cut as a possible replacement for MELBOURNE, it was hard to pass on the offer, despite the fact that the purchase would create numerous logistic, supply and equipment issues, since the rest of the surface force was primarily American-produced or indigenously sourced at that time. After a quick study, Prime Minister Fraser (Liberal Party) announced that INVINCIBLE would be purchased and renamed HMAS Australia. PMS 308 closed and a transition shop was opened in London. MELBOURNE was quickly decommissioned prior to commencing her final yard period, saving the RAN even more money.

Just when all seemed right for the Royal Australian Navy regarding carrier acquisition, the Falklands War reversed the decision of the British Government, which decided to retain INVINCIBLE... Within a few weeks of the British decision to rescind their offer, and following more bureaucratic discussion on the subject, the decision was made not to seek a replacement for MELBOURNE.

The decision was not announced until after pending [Federal] Parliamentary elections, the results of which put the Labor Party back in power. This would seem to indicate that the decision not to purchase a new carrier had, indeed, been made earlier and that the ruling Liberal Party did not wish to upset pro-military voters going into the election. A second factor contributing to the decision was that the Australian economy had just lapsed into a severe recession cycle. Purchasing an expensive piece of military equipment would be particularly unattractive politically, especially given that the cost had skyrocketed immediately after the loss of a bargain basement deal...." [pages 30-33]

Here's the key: The relevant period to calculate is from the point the STOVL starts its conversion to shutdown. If a STOVL is brought in using conventional procedures (which may be the norm for peacetime use) it's going to have a higher fuel burn than if it takes advantage of its capabilities. There may be reasons to do this in peacetime.

Fuel burn is the least of anyone's worries in peacetime. The major benefits for doing conventional landings are in having the ability to bring back more fuel and weaponry than with VL, not to mention reducing wear on the fighter. If one is simply looking at fuel loss alone, then choosing VL will always mean dumping excess fuel. What a conventional landing spends in taxiing to and from the runway really pales in comparison to what is saved overall by not engaging the lift fan.

Something else that may also figure in is that although it'll be easier and probably safer to operate, the F-35B, with its more complex operation may not have all the flexibility of the Harrier in this mode.

How do you mean?

I've been away, and this discussion has moved on, so I'll confine myself here to just responding to your post directed to me. Also, with all respect to Spazinbad, I would posit that the relevant page for this discussion from the AV-8B Naval Flight Manual would be the one I'm attaching here.


Regarding my first point, what I am saying is that if a STOVL aircraft is made to fly the entire pattern for a CL to a runway when doing a VL, then that percentage of time spent at high power is going to be a much larger percent of the overall landing, because the savings inherent in VL have been lost through flying a CL operation. It's true that a VL requires dumping "excess" fuel, but that is true for a CTOL as well. If you want to come back aboard above landing weight, you either dump "excess" fuel or weapons.

Regarding the complex operation I was talking about, I was referring to the different ways the AV-8B and the F-35B do VL. Although the pilot has to do more, essentially VL in the Harrier is point the nozzles down, adjust your hover point, descent with throttle. You have pretty much the freedom to do almost anything during that period.

On the F-35B, first nine doors have to open in sequence, the fan has to spool up (with the FCS determining where the aft nozzle has to be and power changes required as lift from the fan rises) and the control laws change. This is much more complex, but for the pilot it's all automatic at the touch of a button (assuming the software programmers completely understood the whole process and didn't make any flawed assumptions), a much lower workload. However, my understanding is that the idea is to deliver the aircraft to a hover, and there is little freedom during this process or to reposition the aircraft once the hover is achieved, the FCS holding the a/c over the touchdown point. In fact, I believe the pilot input at this point is to move the sidestick until a stop is felt and hold it , and the the FCS controls power and everything else until the F-35B is firmly on the ground. Much simpler for the pilot, but less flexibility. I don't know how the fuel burn in this scenario goes.

aaam, a STOVL jet flying a CL uses a fraction of the fuel that same jet will use performing a VL. It's true that one can shorten a pattern, but that's generally limited by formal convention and procedure, and pilot experience. IOW, STOVL capability does not confer complete independence from the patterns and conventions established by those who own the stuff one intends to land upon. The bottom line is that the more time one spends in semi-jetborne or jet-borne flight the higher the fuel burn rate. Jet-borne flight in Harrier yields a fuel burn rate 3-4x that burned in a CL.

aaam, yes the F-35B can carry out an automatic hover vertical landing and it has demonstrated that ability. However the pilot is able to control it in any phase of flight - within limits - under control of the FCS, which necessarily starts to limit what the pilot can do in certain configurations. However this computer system limits the aircraft in any other flight situation - not just in vertical landing mode. There is a good demo of a vertical landing in the simulator video online at:

http://www.youtube.com/watch?v=OkWuB9wA ... r_embedded
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Just Push ‘Auto-Land’: April 2011
“A Lockheed Martin F-35B short takeoff & vertical landing test aircraft last week achieved an impressive milestone, according to Warren Boley, Pratt & Whitney military en-gines president. “For the first time,” Boley said in an in-terview, “a pilot pushed a button & the [air]plane landed autonomously.” Boley joked that the pilot could fold his hands behind his head or ‘read the paper’ while the air-plane safely settled down to a vertical landing from hover. The flight was the 74th vertical landing of the F-35 test program, & the fact that the Marine Corps was willing to allow the test indicated high confidence in the airplane & its Pratt-supplied F135 engine, Boley told the Daily Report April 8.” — John A. Tirpak http://www.airforce-magazine.com/Pages/default.aspx
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Former Italian F-104 pilot has a go on the F-35 Demonstrator:

How does the F-35 JSF fly and fight? by David Cenciotti – December 21, 2010

http://cencio4.wordpress.com/2010/12/21 ... and-fight/

"...Of particular interest was the opportunity to test the hovering capabilities of the aircraft, that is in fact also available in the STOVL version that interests both the Marina Militare (Italian Navy) and the Aeronautica Militare (Italian Air Force, ItAF). The pilot, by means of a switch manages the transition from conventional flight to the Harrier-style, so to speak. The aircraft autonomously directs the nozzle and reduces the speed to the IAS (Indicated Air Speed) previously set through a dedicated button on the throttle (which is also operated in automatic mode). Once in “vertical” mode, the aircraft is extremely simple to fly, even thanks to the camera underneath the fuselage that allows the pilot to see downwards, and to decide where to place the wheels. Moving the stick forward or backward the aircraft climbs or descends: with a couple of attempts, you can also manage to maintain the desired vertical speed. With the rudder, you can point the aircraft nose wherever you want and even a novice can land with some precision and without major problems.

The only difficulty I encountered during the flight was distinguishing between all the switches on the throttle, that pushed up with the little finger, allowed me to select the autothrottle. As for the rest, airplane is a real dream, extremely easy to be piloted and able to provide the pilot with all the information he might need, in the preferred layout."
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FARNBOROUGH: BAE to ramp up work on JSF production - By Craig Hoyle - 13/07/10 - Flight International

http://www.flightglobal.com/articles/20 ... ction.html

"...Flying an approach to the RN’s new aircraft carrier in sea state six should be a daunting prospect for a novice pilot. But a single button press slows the aircraft to 60kt (110km/h) and automatically configures its flaps and nozzle deflection, making it a matter of merely flying an approach angle of 6-7° towards a series of white lights on the deck. Such design traits go to showcase the F-35B’s attraction for military user and industry alike. Each of the Royal Navy’s ski jump-equipped Queen Elizabeth-class aircraft carriers will be able to carry up to 36 F-35Bs.

UK’s STOVL HERITAGE LIFTS F-35B TEST PROGRAMME
The UK became the originator of short take-off and vertical landing design when in 1960 Hawker Siddeley made the first flight of its P.1127 prototype, the aircraft that would go on to become known as the Harrier. Decades of experience in STOVL design and operation led to the UK becoming heavily involved in the design of Lockheed Martin’s F-35B Joint Strike Fighter. This differs markedly from its predecessor through the addition of supersonic performance, but crucially, also brings a generational leap in how it is flown. The man who knows perhaps the most about new-generation STOVL operations is a BAE Systems test pilot of more than 25 years experience, and who flew the Harrier operationally for the Royal Air Force. This year, F-35 lead STOVL pilot Graham Tomlinson grabbed a place in the history books by making the first vertical landing involving the type. Tomlinson describes the flying characteristics of the Harrier and JSF as being like “chalk and cheese”. “The Harrier has been, and remains, a miracle for the era when it was developed, but the aeroplane can bite you,” he says. “JSF is absolutely transformational. All the pilots say it’s [F-35B STOVL] ridiculously easy to fly, but it should be.”

BAE has around 25 personnel based at NAS Patuxent River, Maryland, where flight testing of the STOVL aircraft is under way, also involving Lockheed and US Marine Corps pilots. Five F-35Bs will make around 1,900 flights during the programme’s ongoing system development and demonstration phase. Achieved by making a single button press, the F-35B’s transition from forward flight to the hover is a world away from the multitude of control demands placed on a Harrier pilot today. “All the conversions done have been faultless,” says Tomlinson, who on 18 March made the first vertical landing using test aircraft BF-1. “There’s a lot of drag when you open that lift fan door, and you as the pilot notice that. But we’ve got plenty of power. When you spin up that [Rolls-Royce] lift fan you’ve got 40,000lb of thrust available: that more than compensates.” Flight testing of the F-35B – the first of three JSF variants to enter service – is at a “careful, cautious & considered” pace...."

Flight test ‘lite’:
Qinetiq’s VAAC Harrier highlights capabilities of Lockheed Martin’s STOVL Joint Strike Fighter
By Craig Hoyle on August 25, 2006

http://www.flightglobal.com/blogs/fligh ... -vaac.html

"...While it is without question one of the greatest engineering marvels of the first century of manned flight, the Harrier is a confusing beast to fly, with more controls to take care of than the pilot has hands. With the F-35B, however, that problem will be no more, and I was assured that after no more than a quick briefing I would be able to fly and land the VAAC Harrier, this time using its so-called unified control laws. After one dummy run with a test pilot looking over my shoulder I locked myself into the domed motion simulator, strapped myself in to the unique Harrier cockpit and prepared to redeem myself in front of the professionals.

Here’s the really good news for anyone reading this who might be pondering embarking on a career as a fighter pilot within the next decade or so: it really will be easy to fly a JSF in the STOVL configuration. Forget the current requirement to control the Harrier’s attitude with the joystick, its forward speed with the throttle and (and here’s the difficult bit) its nozzle control lever to stop it from falling out of the sky. In the F-35B the left-hand will control the throttle inceptor: push forward and you accelerate forwards, pull back and you decelerate and eventually go backwards – and the bigger the input the greater the response. In the hover the right-hand side-stick will be used to control everything else: push left or right and the aircraft will jink to the left or right, push forwards and it will descend, pull back and it will climb. On my two attempts to enter the airfield circuit and land on a pad using visual markers to line the aircraft up I succeeded in getting the VAAC down safely, albeit at a snail’s pace, which did wonders for my dented confidence.

If the modified Harrier’s performance is anything to go by, the stability offered by the F-35B’s liftfan and roll posts will be truly spectacular, with only slight inputs required to manoeuvre it around an airfield or onto the deck of an aircraft carrier or assault ship. And Qinetiq has already successfully demonstrated the VAAC Harrier’s ability to automatically return to and land aboard a rolling and pitching aircraft carrier with centimetric accuracy, meaning that the F-35B’s safety record should be remarkably better than the STOVL platforms it will replace.

It’s not just in the hover that the F-35B will be different to fly. I’ve always found it difficult to maintain the determined height during a turn, but during my simulator ride I found that on each turn I was gaining a considerable amount of height, as my automatic reaction – to pull back on the stick slightly to maintain my altitude – was not necessary in the new generation aircraft. The flight control system knows how much throttle the pilot has requested and will make adjustments during the turn to make his or her life that little bit simpler and free up valuable time for system management tasks.

My initial attempts to hover the VAAC Harrier had been so spectacularly bad in conventional flight mode that my test pilot guide later quipped in an e-mail: “I’m very confident that you have got a good understanding of the differences of control between the old Harrier and where we are going with the JSF control laws!!”

But if all this technology is going to make it so spectacularly easy for a pilot to fly the STOVL variant JSF, what will the next generation of pilots for these aircraft have to boast about over their peers on conventional platforms like the Eurofighter Typhoon? “That’s easy,” says one test pilot: “we’ll still be able to hover!”

Full throttle: QinetiQ c.2002:

http://www.armedforces-int.com/article/ ... ottle.html

"In September 2002, the JSF Program Office announced that a novel integrated flight and propulsion control system – pioneered by QinetiQ – will be implemented in the F-35B STOVL aircraft. QinetiQ, and its predecessor organisations, have undertaken a long running programme of STOVL research with the MOD. This culminated in a three-year programme for the JSF Program Office using QinetiQ’s Vectored-thrust Aircraft Advanced Control (VAAC) Harrier, which has been configured with an experimental fly-by-wire flight control system.

“The standard Harrier is notoriously challenging to fly, which leads to considerable constraints on pilot recruitment and extra de-mands on training”, explains Jeremy Howitt, Technical Manager, Air Vehicle Operations at Bedford.

The Harrier flies like a conventional aircraft at high speed with the pilot controlling the throttle and the aerodynamic control surfaces. As the aircraft decelerates, the pilot must engage a third control lever that rotates the engine nozzles down & enables the transition from wing-borne to jet-borne flight. This requires simultaneous input on all three control sticks – which creates a high workload situation.

“There is also a significantly higher risk of cognitive failure”, explains Jeremy. “Pilots can accidentally operate the throttle when trying to engage the nozzle control and vice-versa –a problem that has caused crashes in the past.

“Recent research has focused on how to make STOVL aircraft as easy to fly as any other aircraft and that’s where we came in.”

Advanced solutions
Using QinetiQ’s ‘Unified’ control concept, the VAAC cockpit controls are linked, via the experimental flight control computer, to the engine power throttle, nozzle controls and tail surface.

The flight control software automatically modulates all three controls simultaneously to maintain the speed and flight path commanded by the pilot.

This removes the need for a separate thrust-vectoring lever and allows the pilot to maintain a simple right-hand ‘updown’ and left-hand ‘faster-slower’ control strategy throughout the whole flight envelope.

The new technology could reap huge benefits in terms of improved safety, reduced training costs, ease of operation and greater operational flexibility...."