F-35B Races Super car

Discuss the F-35 Lightning II
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marsavian

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Unread post09 Feb 2020, 23:45

steve2267 wrote:Marham's airfield is laid out as a 45-45-90 triangle:

Screenshot from 2020-02-09 10-50-55.png


From 0:47 and 1:10 of the video in post #1, they are starting on Rwy 24. First turn is a left, check, 2nd turn a left... check. And if the jet has to make 3 turns, the last one being a left... the jet (anyway) is finishing down Rwy 24 again. So instead of a left 135º turn, he's making a right 225º turn. Rejiggering my math above... 6sec right hand turn @ 7g whilst slowing from 550mph to 400mph (@ -20kts/sec swag per Gums' comment) averaging 20º/sec turn rate, leaving 105º @ 22º/sec (4.8sec)... Total time for turn 11sec (ish), allowing for time to roll in/out of bank... I'm still coming up with...

Mars, does the last right hand turn take 11-12 seconds?


The car starts the last turn at 15:55 supposedly in front but you don't see the F-35B do so although you do see it first around 16:02 having completed around 120-130º and then complete the 225º turn at 16:10 and I am not sure it slows down that much (to 400mph as you suggest) if it has to accelerate along runway 24 to 550 mph. Maybe 12-14 seconds for the last right turn ?

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steve2267

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Unread post10 Feb 2020, 00:42

So I buggered up my numbers a bit. I had been calculating a decel from 550mph to 400mph on the last turn, when it was from only 500mph to 400mph. So 86kts or so. Call it 4 seconds to lose 86kts. Seems reasonable in light of Gums past statements and Dolbe Hanche's comments about how quick it slows down 500mph = 0.66 Mach. 7g turn @ 0.66 Mach ==> 18º/sec. Figure about 22º/sec @ 0.52 Mach (400mph / 350kts). So four seconds @ 20º/sec average (80º) leaving 225º - 80º or 145º at 22º/sec (7g @ 400mph) which is about 6.6sec. So I'm coming up with ~10.6 sec to turn 225º whilst decelerating from 500mph to 400mph. How long does it take a decent pilot to roll into a near 90º bank from straight and level? Half a second? A tad more? I can easily buy 12sec for the total turn. Depending on how the video was presented, I can see difficulty in estimating that 12-14 seconds, especially if you cannot tell exactly when the turn began.

My VPN-fu is weak. Still haven't been able to watch the full video. It appears the episode will air here in the Colonies, though we'll have to wait until March to see it.

FWIW. A fun little mental exercise. Can't wait til I can watch it.

One further EM note... taking Billie Flynn's old quote at face value -- the one about overlaying EM diagrams and the F-35 being as good or better than any 4th gen aircraft... and having read multiple quotes about the F-35 subsonic acceleration compared to F-16 Block 50 chase aircraft...

At sea level, and 7g... at 500mph (0.66 Mach), the Lightning would appear to have a lot of excess thrust still (Ps >> 0)... so in that 7g limiter turn, the Bee pilot would appear to be able to either accel or decel to his hearts content. The 0.52 Mach (400mph) 7g point would appear to be the Bee's sustained turn rate (STR) corner speed, but he can accelerate up from there if he wants, or stay at the corner for min radius / max rate.

I mean, a Viper could do the same, but seems most Viper guys like to drive around at 9g with their hair on fire...

ETA: It is possible the Bee's corner is a bit slower... maybe 320kts or even 300kts... but I don't think so, and here's why:

These guys were competing for honour. Well, maybe not so much honour as bragging rights or who's buying at the pub? rights. So Occam's Razor suggests the Bee pilot was trying to max perform his jet... so he chose 400mph @ 7g for a reason...
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post10 Feb 2020, 03:10

outlaw162 wrote:After you nail down these calcs, QS made an interesting comment about the AV-8A in the VSTOL mode. Wonder how much better or worse off this guy would have been had the rules stipulated a VTO or VSTO and subsequent airborne acceleration instead of the conventional takeoff utilized.


Shack. Aboard ship at lighter CQ weights, a Mode-4 ‘B’ jet accelerates to 80-90 knots in about 400.’ That’s roughly 0-100mph in about 5 seconds.

Here’s an example — https://m.youtube.com/watch?v=cQeIcbhW55Y
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sferrin

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Unread post10 Feb 2020, 03:26

quicksilver wrote:Clean AV-8A, half a bag of internal fuel, w/ water injection — 65/65 STO (nozzle rotation to 65 degrees at 65KIAS/74.8 mph) in roughly 2.5 secs from brake release with well less than 200’ of roll.


This ain't too shabby (0:53)

"There I was. . ."
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Unread post10 Feb 2020, 03:50

sferrin wrote:
quicksilver wrote:Clean AV-8A, half a bag of internal fuel, w/ water injection — 65/65 STO (nozzle rotation to 65 degrees at 65KIAS/74.8 mph) in roughly 2.5 secs from brake release with well less than 200’ of roll.


This ain't too shabby (0:53)



Agree, although to put an exclamation point on it, the air show jet is probably heavier than the jet in the ship STO video I posted.
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steve2267

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Unread post10 Feb 2020, 03:59

FWIW, I downloaded both videos from Youtube and stepped through them frame-by-frame, counting frames from brake release. It's a bit difficult to call exact rotation off the LHD-1, but I counted 180 frames exactly, so 6 seconds. On sferrin's video from 2015 airshow, I counted 185 frames til I could see the mains had left terra firma.

QS, any estimate as to what the WOD would typically be for LHD/LHA flight ops? More a curiosity question. The pilot used all the deck before he rotated.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post10 Feb 2020, 04:02

Steven Steven Steven, (we had 480 mm of rain here over last four days after a prolonged drought - I'm into big numbers).

https://www.abc.net.au/news/2020-02-10/ ... e/11948812

The STO has been described a few times in several threads - I guess I have to go find an example - meanwhile the F-35B flies off the deck by creating lift and not by rotation so it is flying well before the front end is reached. HOKAY? Perhaps that is more relevant to the ski jump STO but still the F-35B is FLYING - off the deck - before it gets to the end to rotate.

viewtopic.php?f=22&t=20138&p=293534&hilit=Ayton+blue#p293534
Blue Sky OPS AIR International F-35 Lightning II
26 April 2012 Mark Ayton

"...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...."

Source: http://militaryrussia.ru/forum/download ... p?id=28256? (PDF)
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Unread post10 Feb 2020, 04:31

steve2267 wrote:FWIW, I downloaded both videos from Youtube and stepped through them frame-by-frame, counting frames from brake release. It's a bit difficult to call exact rotation off the LHD-1, but I counted 180 frames exactly, so 6 seconds. On sferrin's video from 2015 airshow, I counted 185 frames til I could see the mains had left terra firma.

QS, any estimate as to what the WOD would typically be for LHD/LHA flight ops? More a curiosity question. The pilot used all the deck before he rotated.


WOD anywhere from 0-30kts iirc depending on azimuth (relative wind). Spaz posted the wind star for ship ops around here somewhere.

B jet rotates about 50’ prior to bow exit at around 80kts (typical CQ). T/W just over 1:1. AV-8A that I described earlier around 1.4:1. It was about as close as you could get, sensation-wise, to cat shot.

If you look closely, you’ll see that the rotation is effected as the jet crosses the yellow rotation line that is perpendicular to the tram. The clue is the rapid, momentary deflection of the tail plane and exhaust nozzle. Movement of the exhaust nozzle changes the vertical component of thrust between the lift fan and the main engine exhaust thereby lifting the forward part of the jet. That lifting action is stopped/controlled by movement of the engine exhaust downward once again and the tail plane goes to leading-edge up. Genius engineering stuff.

Spaz, unlike Harrier, the B jet has to rotate to create aero lift to augment the powered-lift.
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Unread post10 Feb 2020, 05:08

'QS' Got the rotation on a flat deck STO for the F-35B (I had me mind on the ski jump no rotation - oh well). Meanwhile:
Navy Sees Few Anomalies in F-35B Ship Trials
31 Oct 2011 Amy Butler

"...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 takeoff from the deck, Cordell says...."

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

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

"…STO-ing…
...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
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
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Unread post10 Feb 2020, 05:33

When I was counting frames, I was trying to count until I could tell that the mains had left the deck. Perhaps I mispoke by saying "rotated." Nevertheless, take my counting with a grain of salt, or download the video yourself and count the frames. Zero to flying speed in 5, or 6, seconds is still ridiculous.

But, since the Brits didn't perform a proper comparison... I think the challenge now falls to the USMC to rectify this oversight... and conduct a race between a USMC F-35B in STOVL Mode 4 takeoff and a Ford GT or Hennessy Venom...
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post10 Feb 2020, 07:00

My idea of 'no rotation' (but on the ski jump) is from: [the slow STO as indicated above is like a VTO at slow speed &]
"...The QEC’s ski-jump is longer (200ft) than the Invincible class (150ft) and 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 — giving positive nosewheel 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...." http://aerosociety.com/News/Insight-Blo ... -countdown
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Unread post10 Feb 2020, 19:20

steve2267 wrote:FWIW, I downloaded both videos from Youtube and stepped through them frame-by-frame, counting frames from brake release. It's a bit difficult to call exact rotation off the LHD-1, but I counted 180 frames exactly, so 6 seconds. On sferrin's video from 2015 airshow, I counted 185 frames til I could see the mains had left terra firma.

QS, any estimate as to what the WOD would typically be for LHD/LHA flight ops? More a curiosity question. The pilot used all the deck before he rotated.


Here are the wind stars they used to clear the launch/recovery envelopes during LHA/D testing as well as QEC. You can see that as the relative winds move closer to ship centerline, the acceptable velocity gets higher (up to 40kts).
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