Patuxent River Ski Jump Video (No F-35Bs on it)

[SpudmanWP]

Dragon is spot on as to my point (again, sorry for not being clear enough).

Hardware-wise, there is no difference or hindrance to having the AB engaged for a few seconds prior to the 3BN rotating. You could even have (and would be better to already have) the lift-fan clutch engaged (to some degree) prior to the AB even igniting.

There is an obvious software safety disengage somewhere so they would have to develop and test a takeoff model to include this as an option like they do now for their various takeoff profiles (runways, LHD, ramp, vertical, etc).

[spazsinbad]

'SWP' my sense is that IF this option were possible/feasible/practical then it would have been included in the amazing array of technology on display already. Why NOT ask about this possibility at LM or P&W website? They might give a comprehensive reply one way or another.

Rather than just stating this: "...Hardware-wise, there is no difference or hindrance to having the AB engaged for a few seconds prior to the 3BN rotating...." you might offer some proof?

Same for 'Dragon029' stating this: "...While the nozzle is straight, the lift-fan clutch is disengaged,...". Thanks one and all.

[johnwill]

I too have wondered about positioning the engine nozzle straight back for the takeoff run, then rotating it down for liftoff. In my thought, there is no A/B usage, just max dry power and the fan remains engaged. I understand the that with the nozzle straight back, there is a different back pressure in the engine which could affect the torque supplied to the fan. I'm pretty sure the experts that developed the system know what they are about, so the way it works now is optimum.

The slight pitchup seen just after departing the ramp could well be a programmed AoA increase to develop wing/body lift as airspeed is increasing. AoA on the ramp is zero, thus no wing/body lift, although the tails are deflected downward and may be contributing lift.

[spazsinbad]

Thanks 'JW'. One thought occurred to me - without much after thought is this: how much time from brakes off does this wunderkinder A/B pilot have during the STO to have the 3BSN swivel down enough (not all the way obviously as seen in the video whilst still on deck and on the ski jump). The flat deck STO pilots have commented on the enormous power response experienced during the STO on deck (Harrier pilots say similar things). One day we may know the weight and distance of a particular STO on deck to then time the STO (on a flat deck the F-35B is flying off before the end of the deck) without any edit cuts. Really a NATOPS would be so handy.

And 'JW" from almost the end of page 2 of this thread is this quote:

"...designed so that the aircraft has all three (including the nose) wheels in contact right up until the point where the aircraft leaves the deck [ski jump] — giving positive nose wheel authority throughout. Additionally, the F-35Bs smart flight control system ‘knows’ when it is going up a ramp and will pre-position the control surfaces and effectors to launch at the optimum angle to avoid pitch-up or down...."

So unlike a flat deck STO the Ski Jumper has to have all wheels on the ramp (probably not at 1G perhaps but enough downward force to enable "positive nose wheel authority throughout". The old flight computer is doing a lot of stuff I reckon - let us not overwork it with A/B now.

Here is a more detailed quote about STOVL conversion from conventional flight.

Blue Sky OPS
26 April 2012 Mark Ayton AIR International F-35 Special Edition 2012

"...When preparing to transition from conventional to STOVL mode the first thing the pilot must do is configure the aircraft to be able to fly at slow speed. This process is called conversion and from the pilot’s perspective it starts when the aircraft is moving at 250kts (460km/h) or less at which point he or she simply presses a button.

“Seconds later, assuming all has gone well, you are in the mode that allows the aircraft to go to the hover,” said Peter Wilson.

Nine external doors open in sequence taking about 8 seconds, after which the propulsion system (not to be confused with the engine) starts to spool up. The clutch engages to spool up the lift fan located behind the cockpit (which takes about 5-6 seconds) and the control laws change to make use of the propulsive effectors that have just been brought to life. The aircraft is now in STOVL mode and ready for a vertical landing….”

Source: http://militaryrussia.ru/forum/download ... p?id=28256?

And for difference between FLAT & Ski Jump STOs...

Lockheed Martin rebuts F-35 critics on cost, progress
15 Jul 2010 Chris Pocock

"...For short takeoffs you just power up; the system takes care of everything else. On the ski-jump, for instance, the system detects the change in deck angle & doesn’t apply any rotation as it would on a flat deck.”...”

Source: http://www.ainonline.com/taxonomy/term/ ... node/25359

[SpudmanWP]

I believe the primary reason why it's not there is that it fell on the cutting room floor just like all the other items that were not needed and they could not pay for (in time or money) during SDD.

The most notable of these "not part of SDD but are feasible" features are greater than mach 1.6 top speed and 6 AAMs internal.

Since the US designed the requirement for the F-35B around the existing Harrier operations, it knew what deck size, payload, & range it could use and set the requirement to them.

Things can be added that the plane was always capable of, but not programmed for. Case in point: SRVL was not added to the program until the UK came on board and required it.

[spazsinbad]

'SWP' sure - however this is guess work on your part. I could dream up a lot of stuff and claim it all fell on the cutting room floor. And this A/B STO has not been mentioned... HOWEVER I will admit I was always puzzled by the JBD in the middle of the CVF deck early on (and then the ridiculous A/B conventional takeoffs of the CVF Ski Jump animations are just too much). So... perhaps there was an element of this 'early on' but again this is just guess work on my part.

And from the 'BLUE SKY OPS' article above is another 'Pete Wilson' quote:

"...F-35B Take-off Options
The F-35B STOVL variant has a range of take-off options using different modes to suit the basing. Take-offs from a ship, with either a flat deck or one with a ski jump, are also possible with a mode for each scenario. These are short take-off scenarios that can be achieved at speeds as low as 50kts with a deck or ground run of no more than a 200ft (60m). In the same mode, a take-off as fast as 150 knots is possible if the weight of the aircraft requires that speed. If the aircraft is
light it can take off at a slow speed and faster when heavy.

Take-off at speeds as low as 5, 10, 15, 20kts (9, 18, 27 and 36km/h) are also possible, each of which is effectively a vertical take-off while moving forward. There are different ways of rotating the aircraft in STOVL mode, including the usual ‘pull on the stick’. Other ways are by pressing a button or programming a ground distance required after which, the aircraft control law initiates the rotation and selects the ideal angle for climb-out...."

And the old cowpie throttle for one or tuther.

FLIGHT TEST: F-35 Simulator - Virtual fighter
31 Jul 2007 Mike Gerzanics

“...Seated in the simulator, my left hand fell to the large throttle, called the "cow pie" due to its size and shape, which moves along a long linear track. The active throttle is back-driven by the auto-throttle system and has variable electronic detents for afterburner and STOVL operations. There is no "cut-off" position, a single guarded engine master switch performing that function....”

Source: http://www.flightglobal.com/news/articl ... er-215810/

Pete Wilson again... I would want the LiftFan spinning at brake release - for a STO - no?

Precise and powerful
2012 RR PR

"...when the STOVL doors on the fuselage open, then the Rolls-Royce clutch engages, connecting the LiftFan™ just behind the cockpit via a shaft to the 40,000lb thrust Pratt & Whitney F135 engine. The 3-Bearing Swivel Module at the rear of the aircraft twists downward, and Roll Posts on the wingtips provide stabilising air thrust. The LiftFan spools up in about five seconds, which Wilson says sounds like ‘a big humming mosquito kind of noise. ‘Fifteen seconds after pressing the button, I’m in STOVL mode...."

Source: http://www.rolls-royce.com/defence/cust ... werful.jsp

The FLAT DECK STO difference.

Navy Sees Few Anomalies in F-35B Ship Trials
31 Oct 2011 Amy Butler | Onboard the USS Wasp

"...Though vertical landings are quite similar to those of the Harrier, the STO operations do vary for the F-35 owing to the
different lift qualities of the F-35s’ stealthy, supersonic-capable design. For testing on the Wasp, the nozzles and control surfaces actuate with 225 ft. of runway remaining on deck, creating an angle of attack and allowing for the
wings to produce enough lift for take-off from the deck, Cordell says. The Harrier’s rotation line is at the bow, owing to its wing design creating the required lift without the corresponding angle-of-attack change...."

Source: http://www.aviationweek.com/aw/generic/ ... avy&next=0

And going back to those olden tymes when perhaps more things were possible?

THE JSF STOVL PERFORMANCE PROCESS FROM SMALL-SCALE DATABASE TO FLIGHT TEST DEMONSTRATION
Kevin M. McCarthy, JSF Program Office/Naval Air Systems Command Nov 2002

“...Fixing any two of: a) takeoff gross weight, b) deck run or c) wind over deck, STOPC can optimize for the 3rd parameter.

The STO deck run starts at brake release, which typically occurs at the maximum thrust that the brakes can hold. This is an input. The engine spool-up characteristics from this throttle setting to maximum power are considered during the acceleration portion of the deck run. Weight on main and nose gear is calculated, and must be monitored to maintain adequate deck handling characteristics. The code can represent both flat deck, typical of current generation US Navy ships, as well as any geometry of ski jump. Ski jumps are currently used by the navies of two of the JSF international participants, the UK and Italy....

.....STO demonstrations were a critical aspect of the flight test program as well. The X-35B performed two different technique STOs; 1) fixed nozzle and 2) auto-STOs. The fixed nozzle STOs are self-explanatory, and were used for the initial flight test STO maneuvers. For these maneuvers, the demonstrated performance was very consistent with predicted levels. The flight test auto-STOs featured a deck run nozzle angle (34/28 fan/main) and flyaway nozzle angle between 40/40 and 60/60, depending on aircraft weight. The auto-rotation was pilot actuated at the desired rotation speed....

...STOs are transient maneuvers, and highly technique driven, even for the auto-STOs. The “blind” pre-flight predicted performance estimates differed from the flight test maneuvers....

Source: http://pdf.aiaa.org/downloads/2002/CDRe ... 274d1857TR

And an interesting forum factoid... FROM 'QuickSilver' (HiHO!)

“The nozzle is angled down to ensure directional control (via NWS) is maintained during the takeoff roll until
rotation. You should also note that the nozzle rotates upward momentarily at the point where the takeoff rotation occurs. Such movement instantaneously alters the vertical component of lift between the lift fan and the main engine exhaust thereby contributing to the pitch rotation.”

Source: viewtopic.php?f=57&t=25401&start=15

Jumping Jack Flash
July 2014 unknown author AIR International F-35 Special Ed.

"...There are three ways to conduct a short take off (STO) in the F-35B: stick STO, button STO – and auto STO. “That’s a completely automated way to STO the aircraft off the flight deck. You punch in a distance and the aircraft will auto rotate to its optimal fly-out condition. It’s all based on distance: we know where the aircraft is spotted [before it starts its take-off run] and where it should start its actual rotation,” explained Rusnok. “Unlike a Harrier, which launches off the end of the ship flat, the F-35 rotates at about 225 feet from the bow, sits on two wheels until it gets to the end of the ship and actually takes off, a much different process to a Harrier. From a pilot perspective, you lose some sight of the front of the ship; in a Harrier you can see all the deck. But that’s all part of optimising a 35,000lb aeroplane to get off the ship compared to the Harrier, which is only 16,000 to 25,000lb.”

With stick STO the pilot controls the take-off by pulling back on the stick, holding it there and then rotating to the optimal pitch angle to fly off. In button STO, the pilot uses a trim switch which rotates the aircraft when pushed in, activating it when the aircraft passes the yellow STO rotation line positioned 225 feet from the bow of the ship.

“That was a temporary marking applied on the flight deck for this trial and is now being permanently installed on the ship with lighting,” explained Rusnok. “It’s based on optimising the performance of the aircraft and its flying qualities, so we can get the aeroplane off with the maximum amount of nozzle clearance and performance. The STO line is our visual cue to either pull the stick aft or hit the button; or if you’re on automated STO you should start seeing the aeroplane’s flight controls moving by the line, otherwise the pilot can intervene and pull back on the stick. We’ve never had to intervene.”

The pilot also has command of the throttle. Two power setting options are available for take-off: Mil STO and Max STO, as Maj Rusnok explained: “When you taxi to the tram line you stay in mode one, the conventional flight mode. You convert the aircraft into mode four, the STOVL flight mode, and it takes about 15 seconds or so for the doors to open up and the lift fan to engage.

“Then you push the throttle about halfway up the throttle slide into a detent position at about 34% engine thrust request. It sits there and you check the engine gauges: if the readings are okay you slam the throttle to either Mil or Max position and then release the brakes simultaneously. Pushing through to max is like an afterburner detent. But it’s not an afterburner – you can’t go to afterburner in mode four.

“It’s a very fast acceleration. The closest we would spot from the bow is 400 feet, so about 175 feet before we would actually start rotating the aeroplane [at the STO rotation line]; so very, very quick.”

One of the big test points for DT I was to ensure adequate nozzle clearance in all the different test conditions. The engine nozzle swings down and back up during the take-off in accordance with inputs from the aircraft control laws.

“It’s all automated,” said Rusnok. “The pilot is not in the loop whatsoever – either they’re pushing the button and letting the aeroplane do its own thing or pulling back on the stick to help it. Monitoring systems cue when something is wrong, so you have to rely on them to keep you safe because the flight controls are being moved unbelievably quickly.” Maj Rusnok said the take-off was very much like that ashore, with very little sink off the end of the deck. “The aeroplane is ridiculously powerful in STOVL mode. Just raw, unadulterated power.”..."

Source: AIR International F-35 Special Edition July 2014

AND maybe the last Ski Jump?

Stepping-Stones
08 SEP 2014 Tony Osborne AVIATION WEEK & SPACE TECHNOLOGY

“…Particular emphasis has also been placed on how the F-35 will launch from the Queen Elizabeth’s ski jump, which gives the aircraft valuable vertical impetus, allowing for greater takeoff weights as well as a positive rate of climb. The F-35B’s flight control logic has been written for the Queen Elizabeth’s new 12-deg. jump, which at 200 ft. long, is some 50 ft. longer than that used on the Invincible-class carriers.

With the aircraft lined up for takeoff, the pilot presses the short-takeoff-and-vertical- landing (STOVL) switch, activating the lift fan and rear nozzle. The lift fan is fully operational within 15 sec. The F-35B uses the same process and partially opens its weapons bay doors, which help provide more lift. [Perhaps it was meant that this is for the VL?] As the aircraft hits the ski jump, its flight control logic recognizes it is on the ski jump and uses the rear nozzle to keep all three wheels on the ground. The aircraft should be airborne at around 90 kt.

“It’s a luxurious way to get airborne,’’ says Wilson. “The pilot simply uses the pedals to keep the aircraft straight, and the aircraft recognizes the presence of the ski jump.” Test pilots have tried out the ski jump only in the simulator, but that work has been very valuable in addressing early concerns about the ground clearance between the ski jump and rear nozzle….”

Source: AVIATION WEEK & SPACE TECHNOLOGY 08 SEP 2014

MODES sort of explained...

F-35 Flight Testing At Pax
15 October 2012 Eric Hehs

"...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.”...”

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

[quicksilver]

As noted by Maj Rusnok in one of the clips above, AB is inhibited when the jet is in Mode 4 -- no exceptions, including the SWP video from Pax STO in 2010 (JW is generally correct about why).

The jet knows how much it weighs, where that weight is distributed (CG), and the propulsion system balances the horizontal and vertical components of lift (thrust split and thrust angles) between the lift fan, the main engine and the roll posts in response to pilot commands via the inceptors (stick and throttle).

The lift fan produces a significant vertical lift component even with the vane box nozzles at the aft-most defection. As a result, for STOs, the lighter the jet is the more downward deflection it needs from the main engine to keep the nose wheel firmly on the deck to provide directional control (via NWS) during the takeoff roll. Conversely, if the jet is heavier, main engine exhaust deflection is somewhat less.

If one looks very closely at about the 7-8 second mark of the SWP video, one can see a couple points on the 'feathers' of the main engine nozzle and also see the slight upward movement of the nozzle at the STO rotation point at about the 9 second mark.

[noth]

IT'S HAPPENED!!!!!!!!!!

http://www.flightglobal.com/news/articles/f-35b-demonstrates-short-take-off-capability-413986/

The UK and USA have carried out the first short take-off test of the Lockheed Martin F-35B Lightning II during a ground-based test at Patuxent River Naval Air Station in Maryland, USA on 19 June.

This marks the start of the first phase of testing to certify the UK’s short take-off and vertical landing F-35B as capable of take off and landing from an aircraft carrier. The work is being controlled by the F-35 Pax River Integrated Test Force (ITF), assigned to the Air Test and Evaluation Sqn 23.

Test aircraft BF-04 took off on a ski-jump, demonstrating the F-35B’s ability to integrate into the UK’s future operations. The UK has selected the ski-jump approach as opposed to the catapult and arresting gear approach favoured by the USA in its carrier operations.

[Dragon029]

IT'S HAPPENED!!!!!!!!!!

[/quote]

Yep, go to the 2nd page of this thread to see video.

[spazsinbad]

These guys should not write about naval aviation or the partners in the JSF/F-35 program. Significant - Eye Candy - I lost my sense of humour with them a long time ago when they could not tell the front / back of a CVN with an X-47B on/off it.

http://breakingdefense.com/2015/06/eye- ... -takeoffs/

[spazsinbad]

Janes gets into the spirit of the event (unlike defaerospakfilla for example - a quote from dem follows - then JANES).

"(EDITOR’S NOTE: The above story, written by the chief JPO spokesman, was posted on a Pentagon news distribution website (DVIDS) late Tuesday night, but as of this morning neither the Navair [Why is this important - how relevant to USN NavAv are ski jumps? IS every test mentioned by NavAir?] nor JPO [here: http://www.jsf.mil/news/docs/20150619_SkiJump.pdf ] websites mention the test." http://www.defense-aerospace.com/articl ... -test.html [Weerd Huh] but this is a weirder: https://www.f35.com/news/detail/f35b-je ... ns-testing THIS PAGE does not appear in the 'news section' but it points to UK MoD baby - rock on whoever is responsible LM]

F-35B begins 'ski-jump' trials for carrier operations
23 Jun 2015 Gareth Jennings, London - IHS Jane's Defence Weekly

"The Joint Program Office for the Lockheed Martin F-35 Lightning II Joint Strike Fighter (JSF) has begun ground-based trials of the 'ski-jump' technique for launching the aircraft from the decks of aircraft carriers, the UK Ministry of Defence (MoD) announced on 23 June.

In the test, which relates to JSF's short take-off and vertical landing (STOVL) F-35B variant, the chief STOVL test pilot from BAE Systems, Peter 'Wizzer' Wilson, took off from Naval Air Station (NAS) Patuxent River in Maryland using a ramp that had been fitted to the Royal Navy's now-decommissioned HMS Illustrious. [WHAT BOLLOCKS!]

Wilson said the test on 19 June re-proved the concept developed by the UK to launch its Sea Harrier jets from the decks of its through-deck cruiser carriers in the late 1970s. Whereas Harrier pilots had to manually rotate the aircraft's exhaust nozzles slightly forward immediately after take-off to provide additional lift, the control surfaces and jet nozzle are adjusted automatically for pilots of the F-35B.

The 'ski-jump' concept enables the aircraft to take off with more fuel and/or weapons while using less deck space to build up speed, and provides an extra safety margin.

"The real benefit is one of timing," Wilson previously told IHS Jane's . "Once airborne, you are flying upwards rather than horizontal, and this gives you extra time to think if something should go wrong." Also, as was found during the Falklands conflict in 1982, the concept allows aircraft to be launched in far rougher sea states than possible with a conventional carrier equipped with catapults.

For the F-35B, the 'ski-jump' will be used to launch jets from the decks of the Queen Elizabeth and Prince of Wales carriers being built for the UK Royal Navy, and may be adopted by other customers such as Italy. Phase I testing will continue for two weeks, ahead of the Phase II trials to take place through the third quarter of the year. The MoD did not disclose what Phase II will entail, but it will likely feature shipborne trials aboard the Queen Elizabeth (QE) aircraft carrier (the first of the two QE-class ships) [AGAIN BOLLOCKS - ship trials 2018]...." [THEN follows a bunch of info about other CVF stuff]

Source: http://www.janes.com/article/52509/f-35 ... operations

[spazsinbad]

I LUV this shite - it is all so 'freekingly complicated - and EXPENSIVE' what oh laddie - take a shower (sewer preferably).

http://www.wired.com/2015/06/wildly-exp ... mp-launch/

[spazsinbad]

Now here is something more sober and useful to contemplate....

British pilot is first to test F-35B ski-jump launch
24 Jun 2015 BAE Systems Manufacturing Group

"Washington – The launch took place at Naval Air Station Patuxent River, Maryland, on June 19, 2015, from a land based ski jump and marks the start of an initial testing phase expected to last two weeks. The trials demonstrate the aircraft’s ability to take off safely and effectively from a ski-jump ramp similar to that which will be used on the UK’s new aircraft carrier. Ski-jump ramps provide the aircraft with an upward flight path meaning the aircraft can take off from the available distance with a greater payload, which means more weapons.

BAE Systems test pilot Pete Wilson said: “It’s always exciting when you get to do something in aviation for the first time. We spend literally years planning these ‘firsts’, with hundreds of hours in the simulator as the event gets close, but even with all the preparation the test team remains focused on the potential that something unexpected might happen. As is usually the case, the jet performed as expected and it was a real pleasure.”

BAE Systems plays a key role in the design, development and manufacture of both the aircraft and the aircraft carrier, and also leads the work to ensure that both are integrated seamlessly for the UK customer. These recent trials continue to inform the F-35 program and the BAE Systems engineers involved in it on both sides of the Atlantic. That includes BAE Systems flight test engineers based in the U.S. and engineers in Lancashire helping to develop and test the latest technologies for the aircraft.

In Warton, Lancashire, UK, the data from the flight trials will be used to further improve the models used in a unique simulation facility. Using the latest cutting edge technologies, engineers have developed a simulator that allowed pilots and engineers to fly the F-35 from the deck of the Queen Elizabeth carrier before either are available. This facility remains at the heart of developing a carrier strike capability for the UK...."

Source: http://www.onlineamd.com/british-pilot- ... 62415.aspx

[spazsinbad]

Navy’s new F-35 jump jet flies from trademark ski ramp for first time
23 June 2015 RN Navy News

"...Veteran test pilot Peter ‘Wizzer’ Wilson took off in an F-35B using the jump – identical to those fitted on the Royal Navy’s new carriers.

...Ski jumps were fitted to the RN’s generation of Harrier carriers to give the jets more lift with less speed than a conventional flat flight deck.

The concept has been retained with the Queen Elizabeth class – although the replica ramp has been built in Maryland, not Yeovilton.

On the new carriers the structure rises about six metres (20ft) above the normal deck.

Two weeks of initial trials are being carried out with the data gathered fed back by the test team to engineers and designers, including those at Warton in Lancashire where F35 simulators help pilots ‘fly’ from the deck of HMS Queen Elizabeth – before they do it for real from 2018 onwards."

Source: https://navynews.co.uk/archive/news/item/12935

[spazsinbad]

IF youse want a LaFf then go to the TidierRogerAway website to NOT only view the Obligatory Animated GIF [ https://i.kinja-img.com/gawker-media/im ... 907823.gif (2.8Mb) ] but see how the rong details are just that (probably at least one copied from a Shalal Reuters 'less thrust wrongun' earlier). Some jawdropping claims - as per usual.

F-35B Makes Its First Leap Off The Ski Jump
23 Jun 2015 Tyler Rogoway

"...This test was delayed last winter by about five months without a stated reason. [AND for four years without a reason stated.] Then, with little notice, this video was released by NAVAIR, Lockheed and BAe Systems showing the test in progress. Maybe that’s a function of just how unforgiving this type of test can be. If something goes wrong with the jet at such a low energy state and slowly climbing out at low-altitude and high angle of attack, mitigating any major issues probably has more to do with pulling the ejection handle than troubleshooting in the cockpit...." [No Kidding - and it will be automatic - numnuts]

Source: http://foxtrotalpha.jalopnik.com/f-35b- ... 1713406488