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Discuss the F-35 Lightning II
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Gums

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Unread post14 Mar 2012, 17:42

Salute!

See:

http://www.flightglobal.com/blogs/the-d ... ng-ii.html

Interesting, and last month talked with a pilot or two that commented about the vertical landing mode.

They didn't use the throttle for vertical control, but rather the stick. Apparently, the horizontal motion is controlled with a "hat switch" on the throttle grip. Forgot to ask them about directional control, and it's prolly the rudder pedals. And that would make horizontal translation a left-right stick deflection.

The pilots said it was lots easier than the Harrier, and ex-Harrier folks adapted instantly. Push forward on stick and go down, pull back and go up, let go and stay where you are.

Anybody have more on this concept?

Gums sends...
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Unread post14 Mar 2012, 18:37

Gums-

I remember talking to someone with the program and they said they made the hover mode (Mode 4? IIRC) controls the same as conventional flight controls. The goal was to make it more intuitive to pilots. Also he said almost all Harrier pilots crash the sim the first time, while non-Harrier pilots have no problem with hover mode.

Action: CTOL Mode reaction vs. STOVL Mode reaction
Push Throttle Forward: More Power/Go Faster/Forward Acceleration vs. Move Forward
Pull Throttle Back: Less Power/Go Slower/Backward Acceleration vs. Move Backward
Pull Stick Back: Nose Up/Go Higher vs. Go Higher
Push Stick Forward: Nose Down/Go Lower vs. Go Lower
Push Stick Right: Roll Right/Move Right vs. Move Right
Pull Stick Left: Roll Left/Move Left vs. Move Left
Rudder Left: Rotate Left vs. Rotate Left
Rudder Right: Rotate Right vs. Rotate Right

Anyway I have no flight experience but from the sim I have flown it seems very intuitive to me.

Sufa Viper
Last edited by sufaviper on 14 Mar 2012, 18:39, edited 1 time in total.
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Unread post14 Mar 2012, 18:38

I think the automation is amazing and am sure it will dramatically reduce accident rates vs. the Harrier. On a related note to Gums' question, I am infinitely curious about the backup procedures/mechanisms in place during the B's transition and zero airspeed phases. With the additional dependence (and added possible point of failure) of the software,
- What sorts of backup modes does the FLCS software have to compensate for sudden mechanical issue i.e. nozzle issue / FOD / loss of thrust or symmetrical thrust etc
- If the computer fails is there an auto-eject sequence or is the pilot trained to be ready to recognize it and pull, etc

Gums, I always enjoy reading about your war stories and input on here. Look forward to hearing replies to your post.


- Jetnerd
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LinkF16SimDude

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Unread post14 Mar 2012, 18:55

The fact you can let go of the controls and it'll hold the hover shows just how far the VSTOL/STOVL world has come. You never.....NEVER....let go of ANYthing when hovering in the Harrier. If you could steer the jet with your butt crack you'd use it. :wink:
Last edited by LinkF16SimDude on 14 Mar 2012, 20:26, edited 1 time in total.
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Unread post14 Mar 2012, 19:24

Salute!

Thanks for nice words, Nerd

@ Link, et al I have the V-22 Dash One and it resembles the F-35 concept. It also does the magic hover trick. The one here at Eglin would zoom in at 200 feet and come a dead stop and sit there as if on a pedestal.

V-22 uses a left right switch on the collective/stick for translation and rudders to point the nose. The nacelle angle is a roller switch on the throttle.

As far as backup modes, only one I can see is a conventional landing. If the primary sftwe goes Able Sugar, then like the Viper you have nothing left but that handle between your legs.

Heading out to base now to try to get a glimpse.

Gums sends...
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Unread post14 Mar 2012, 20:12

sufaviper wrote:Gums-

I remember talking to someone with the program and they said they made the hover mode (Mode 4? IIRC) controls the same as conventional flight controls. The goal was to make it more intuitive to pilots. Also he said almost all Harrier pilots crash the sim the first time, while non-Harrier pilots have no problem with hover mode.

Action: CTOL Mode reaction vs. STOVL Mode reaction
Push Throttle Forward: More Power/Go Faster/Forward Acceleration vs. Move Forward
Pull Throttle Back: Less Power/Go Slower/Backward Acceleration vs. Move Backward
Pull Stick Back: Nose Up/Go Higher vs. Go Higher
Push Stick Forward: Nose Down/Go Lower vs. Go Lower
Push Stick Right: Roll Right/Move Right vs. Move Right
Pull Stick Left: Roll Left/Move Left vs. Move Left
Rudder Left: Rotate Left vs. Rotate Left
Rudder Right: Rotate Right vs. Rotate Right

Anyway I have no flight experience but from the sim I have flown it seems very intuitive to me.

Sufa Viper


If memory serves me, Sufa is correct. However, 'Harrier guys crashing it first time' is apocryphal. Nobody crashes it first time unless they try to. Harrier guys do have to unlearn left-hand habits.

Couple points --

After converting to Mode 4, a motor in the throttle quadrant moves the left inceptor (throttle) to a detent position at roughly the middle of total throttle travel. Movement out of the detent either fwd or aft commands acceleration or deceleration in the y axis. If one pulls the throttle all the way aft to the stop, the jet will decelerate past zero fwd airspeed to its limiting rearward speed (I don't know what that speed is). If one firewalls it, the jet will go to its limiting speed in Mode 4 (250 IIRC). Pilot also has option to command airspeed (in as little as one-knot increments) with a HOTAS activation on the throttle.

Believe what Gums described (hat on the throttle) is called TRC -- translational rate control - which allows more precision and finesse of aircraft movement in proximity to the ship (one uses ones fingers as opposed to ones arm).
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Unread post14 Mar 2012, 20:46

Pic from the London Simulator here (repeated here now): http://www.f-16.net/index.php?name=PNph ... don#218846
http://www.flightglobal.com/blogs/the-d ... 153708.jpg
now:
http://www.f-16.net/attachments/f_35per ... 08_191.jpg

Image
________________

OLD CLASSIC QUOTE:

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

"...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.”..."
________________

Single Minded Flight International 17 August 1999

http://www.flightglobal.com/pdfarchive/ ... 02360.html

"Experienced Harrier test pilot John Farley evaluates control concepts being considered for STOVL variants of the JSF..."
Last edited by spazsinbad on 14 Mar 2012, 21:31, edited 2 times in total.
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Unread post14 Mar 2012, 20:52

'jetnerd' asked (amongst other things) "...If the computer fails is there an auto-eject sequence or is the pilot trained to be ready to recognize it and pull, etc ...." This and the other questions covered in part in other threads as I recall although software specifics not specifically I guess. However there is an 'auto eject' function with dial in sensitivity that will auto eject the pilot in hover mode within as I recall 0.6 of a second. I'll just repeat that factoid below soon... [yep I'll get there...]
_______________

Test Flying The Joint Strike Fighter Talk by Graham Tomlinson 9th Feb 2011

http://myweb.tiscali.co.uk/hawkerassoci ... ghter.html

"...The STOVL mode control system is derived from ‘Unified’ developed by the ‘RAE’ on the VAAC Harrier. The throttle commands acceleration and deceleration (or thrust on the ground and in the STO mode, and in all conventional modes); in the hover the stick moved backwards/forwards commands upwards/downwards vertical velocity (or pitch rate elsewhere); in the hover the stick moved from side to side commands bank angle (or roll rate elsewhere) and if released returns the aircraft to wings level; in the hover the pedals command yaw rate (or sideslip elsewhere).

Future development will clear full envelope autopilot/auto throttle, automatic deceleration to a spot, and TRC (translational rate command) which in the hover allows the pilot to make small positional corrections easily, and will then bring the aircraft to a standstill if the pilot releases the controls. A pilot’s helmet mounted display (HMD) is fitted instead of a HUD.

In the Harrier the pilot must obey the rules. The F-35B fly-by-wire system gives angle-of-attack and sideslip control, and departure protection. Further pilot workload reduction is given by performance deficit protection, conversion speed window protection and FOD protection warning; and flight test has a watching brief on the requirement for possible tail strike protection during slow landings (currently not considered necessary). Pilot cognitive errors (of trying to control thrust with the throttle) have been mitigated in the design. In the unlikely event of the lift fan failing catastrophically the aircraft would pitch inverted in 0.6 seconds, and the pilot is protected by auto-ejection signalled by pitch rate and attitude (derived from the YAK 38 & 141 systems)...."
____________

Despite skepticism from some at the time, here is an old news item (significant '74th landing' factoid].

Just Push ‘Auto-Land’: 08 April 2011 — John A. Tirpak

http://www.airforce-magazine.com/DRArch ... -Land.aspx

“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.”
Last edited by spazsinbad on 14 Mar 2012, 21:27, edited 2 times in total.
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Unread post14 Mar 2012, 20:59

Looking for factoids here are some (also on other threads but repeated here because apppropriate).

Vertical Validation by GUY NORRIS | LOS ANGELES

Aviation Week & Space Technology; October 3, 2011; pages 31-32

"...Speaking at the Society of Experimental Test Pilots symposium in Anaheim, Calif., last month, Wilson said results vindicate the simple design concept of the “unified” Stovl control mode. The mode is activated by the push of a “decelerate- to-hover” button in which the throttle commands acceleration and deceleration in the hover. In this mode, the stick commands upward/ downward vertical velocity with a backward-forward motion, while in the hover mode sideways movement of the stick commands bank angle. If released, it returns the aircraft to wings level. Pedals command yaw rate in the hover.

The fastest descent rate, as controlled by pushing the stick forward, is set at 7 fps., though the testing has included rates as low as 4 fps. and high as 12 fps.

Testing has also focused on the translational rate command (TRC) mode, which in the hover allows the pilot to make small positional corrections and which brings the aircraft to a standstill if the pilot releases the controls. “It is used to capture the current longitudinal groundspeed and is important for precise positioning in shipboard operations,” says Wilson...."
_____________________________

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

"...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...."
___________________

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

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

"...Lt. Col. Matt Kelly, the lead F-35 test pilot at Patuxent River, originally a Hornet pilot, says that his first time conducting a vertical landing on an L-class ship was with the F-35B. “The challenge is not ‘am I going to get my aircraft onboard,’” he says. “The challenge really becomes ‘can I put my nose tire in a 1 ft. X 1-ft. square box where I want to on the deck.’ That is really a testament to the flight controls and the tools that pilots have.” Kelly acknowledges that the deck motion does impact landing operations, but “the control law you have is so good, you can compensate.”..."
____________

The F-35 Pilot 08/19/2011

http://www.sldinfo.com/the-f-35-pilot/ | VIDEO: http://vimeo.com/27918352

"...Another USMC test pilot, indeed last year’s test pilot of the year, “Squirt” Kelly told us what he had learned since our visit last year: What I have learned for sure since your last visit is how to do a vertical landing. As an F-18 pilot, I don’t have any background in hovering or operating in that whole STOVL world. With probably fewer hours than a guy is going to have going through the training command and doing this through the simulator training to the flight, it was easy. For guys graduating out of the training command, it was a process of learning step-by-step, follow the procedures, and hover. You can let go of the controls. It just kind of stays where you put it.

QUESTION: So it is not Harrier like at all
Kelly: Not at all. In a hover and in a vertical landing, it’s a no-brainer. It’s push the stick forward. There’s even a descent button in the stick, which you use. The airplane lands itself. It is very much forgiving to a guy who’s doing it for the first time, and it makes him look good. In a hover and in a vertical landing it’s a no-brainer.”
Last edited by spazsinbad on 14 Mar 2012, 21:35, edited 1 time in total.
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Unread post14 Mar 2012, 21:16

There is a lot of recent material about STO Short Take Offs but only this for starters...

The Lockheed Martin F-35 Joint Strike Fighter (JSF) v2.0.6 / 01 may 10 / greg goebel / public domain

http://www.vectorsite.net/avf35.html

[3] F-35 IN DEVELOPMENT [Short Take Off - STO]
"...The pilot flies the aircraft with "hands on throttle and stick (HOTAS)" controls; the PCD is touch-sensitive and functions to an extent as a reprogrammable keyboard, resulting in a spare cockpit control layout.

The "smarts" of the F-35 will be particularly appreciated by pilots flying the F-35B STOVL version. Short takeoffs in the Harrier are a troublesome affair that require the pilot to have "three hands": one for the throttle, one for the stick, and the third for the lever that controls the direction of the Harrier's swiveling exhaust nozzles. An F-35B pilot, in contrast, flies the plane with stick and throttle, with the software handling the fine details of short takeoff: the pilot will simply press a "button" on the PCD to convert from vertical to forward flight or the reverse.

While the Harrier has reaction control thrusters driven by engine bleed to provide low-speed maneuverability, the F-35B simply modulates the four points of its vertical-lift system -- the pivoting exhaust, the two wing exhaust ducts, and the lift fan -- to provide control. This trick would be difficult or impossible to do manually....”
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Unread post14 Mar 2012, 21:35

Spaz -

As always you are a wealth of knowledge with references especially with shipborne aviation questions on here. I didn't realize the backup systems were already discussed somewhere on here. Interesting that the Soviet VTOL jets already had roll-rate/moment-triggered auto-ejection. So, it must not have been a big deal to build that safety measure into the F-35B. I can imagine even an alert pilot not being able to pull the handle in time if the worst happened, i.e. sudden, complete failure of a single roll post on one side. Thanks!
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Unread post14 Mar 2012, 21:38

'jetnerd' no worries. As you can guess this stuff really interests me and it can all be found + MORE :-) in the "how to deck land" PDF mentioned recently elsewhere. The above material has been excerpted from this same PDF [dated March 2012] available online at: http://alturl.com/4a4ko

There is a discussion about the 'backup/redundant' computer flight controls on this forum while most of the above is scattered or homogenised in other various threads. Search forum for article author names to find stuff easily enough.
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Unread post15 Mar 2012, 03:17

The pilots said it was lots easier than the Harrier, and ex-Harrier folks adapted instantly. Push forward on stick and go down, pull back and go up, let go and stay where you are.


Don't think a former AH-1, CH-46, or CH-53 pilot would do well with these controls on the first time.
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Unread post15 Mar 2012, 03:32

Pilots undergo training/retraining if changing from aircraft to aircraft/type. I'll imagine any helo pilot will use the F-35 simulation trainer a lot before going flying & before going Vertical Landing in STOVL mode for real..
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Unread post15 Mar 2012, 14:01

My comment concerning the Harrier guys crashing on thier first VL attempt was related to the first time they hopped into the sim years ago, without any prior training. They crashed because they reacted like they were in a Harrier, control input wise.

Agreed with spazsinbad on the training/retraining. The sim operator I was talking to mentioned that after a couple tries the Harrier guys had no issues either. Tt was more intuitive to non-Harrier pilots, because they had not been trained in the "Harrier VL arts."

Sufa Viper
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