F-35 and Airshows

Discuss the F-35 Lightning II
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lbk000

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Unread post05 May 2019, 18:32

Calm down, I see certain words have incited your blood pressure and temperature to rise. You're not wrong. We're not at the stage yet where we can throw out BFM. I'm just saying that on the whole sliding scale from BFM <--> UFO, the newer platforms allow for a bit more towards the UFO techniques, opening up moves that once were off limits to other aircraft. For example, the FA-18 would have less latitude to fully abuse its instantaneous rate, because it lacked the acceleration to recover from it. So what if you fixed that caveat?

Also the sharp high alpha instantaneous "square turn" isn't in defiance of good BFM concepts. Cutting speed lowers radius, lower radius gets you more angle. This isn't new to the F-35, this can be seen abused in classic matchups like A6M vs F6F. Even if the A6M is slower, if the F6F turns, then radius gets abused into closure. You can catch up even as a slower aircraft thanks to geometry.

The military is a place that's riddled with cases where slow is fast.
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marsavian

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Unread post05 May 2019, 19:03

Yes, high acceleration from low speed is what turns you from a sitting duck into an aggressive maneuverer, the F-35 does the 135 degree bat turn and then goes straight into a climb, so it's changed both its nose angle and direction of flight in a short time. Listen to what the F-35 pilots like Dolby are saying along the lines of we tried being more AoA aggressive and it worked meaning this actually works in ACM. As the F-35 gets more powerful engines this feature will only be enhanced. As for F-22 TVC DACT problems the context there was that TVC AoA changes were employed in a steady turning state and energy reduction occurred over time. The purpose of these sharp AoA changes is to change direction abruptly then proceed sharply in the new direction not an attempt to increase one's sustained turn rate. This is an issue that can be fixed with training and no doubt has.
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steve2267

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Unread post05 May 2019, 20:32

Upon further reflection, and reading these replies, perhaps i was too hasty and impestuous in my post. And I recall that I too have posted in the past, wondering aloud in other threads about the ability of the F-35 to slow down to execute a smaller radius turn, and using its acceleration to regain energy. For example, how can the F-35B be dangerous in BFM if it is not a 9G airframe? Possible answer: by slowing down 50-100 kts (or whatever the number may be) where a 7g turn will generate similar rates to the Air Force 9g stud, but with a smaller radius, then utilizing that wonderful motor to regain energy. However, I was envisioning maneuvers in the, I dunno, 250-350 kt range, whereas these high alpha square turns would seem to be bleeding airspeed down well below 200kts (a guess on my part).

All I'm saying is that I don't think you can toss out the window everything learned in ACM / DACT / BFM for the past 60 years, and that there is a reason the phrase speed is life was coined.

That said, I still take quicksilver's words to heart when he said there is a time and place to trade energy for angles with a high alpha / holy sh*t move... but if not done well, you are a strafe rag waiting to be gunned until you manage to regain your E.

Apologies if my previous post was too sarcastic.
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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f-16adf

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Unread post05 May 2019, 20:57

99.9% of people don't understand that a jet can also be executing "decelerated turns" v "sustained turns". Speed is life because a jet can hit 9G and then decelerate down to say 6G. As in the case of the F-16, he can hold turn rate all the while shrinking the corresponding turn circle.

The overwhelming majority of people on other aviation forums simply don't comprehend this concept. When they think of turning and EM charts they only see Sustained Turning.
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lbk000

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Unread post05 May 2019, 21:45

Speed is life is probably one of the most misunderstood phrases. It, as with everything in the knifefight, is a relative concept, not an absolute. There is "out of airspeed and out of ideas" (= losing) and there is "slow with ideas" (= winning). Aircraft like the Tomcat and Hornet are perfectly at home in the 2-300kt range and even comfortable below that, getting angles on you even though they're only pulling 4-6g's.
And there is a very real thing as being too fast.
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f-16adf

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Unread post05 May 2019, 21:56

If the Tomcat wants to hold Ps=0 at .6IMN (about 325KCAS), that's all well and good. But he's a one trick pony. The F-16 on the other hand can be at -200, -400, -600, -800 Ps at .6IMN all the while with a better turn rate and slightly smaller turn radius.
Last edited by f-16adf on 06 May 2019, 02:39, edited 1 time in total.
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lbk000

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Unread post05 May 2019, 22:20

That's both irrelevant and a distraction to the point I'm trying to make (also, good job suddenly reverting to the sustained-turn argument the moment it suits your purpose, despite just pointing out the folly of it prior).

The maneuvering fight can be much more dynamic than simply playing circle games. For example, if you're in the better accelerating aircraft but you're both fast, how do you go about abusing that acceleration game when going any faster starts becoming counterproductive? You expedite winning the fight by taking it to a different regime and changing the energy level of the fight. If you take both yourself and the adversary to the slow end, all of a sudden your airspeed overhead gets uncapped, and voila, you got all that room to abuse your acceleration advantage. You will hurt, but your enemy will hurt more.

Unsustainable turns are a wonderful tool when you have the means to follow up.
Think about it this way: "I have a bandage and he doesn't; If we both cut ourselves, then I will live and he will die." This is the essence of how to abuse aircraft characteristics beyond Ps=0.
Last edited by lbk000 on 05 May 2019, 22:31, edited 1 time in total.
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f-16adf

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Unread post05 May 2019, 22:31

The Tomcat can't hold turn rate at -200 and above, his Ps are not near horizontal like the F-16, but nearly diagonal. That is why I put the F-14 at Ps=0 (his best game). Since he would be losing more airspeed and rate if he tried to match the Viper decelerating.
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lbk000

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Unread post05 May 2019, 22:34

I'm here trying to explain how to win with a slow game, and that's an issue more relevant to the F-14 than it is to the F-16 because it has a weird dynamic where it's sustained turn isn't great, but it's minimum radius is excellent and it's not so great going into the fast end.

You keep trying to bring it back into rate comparisons when I'm trying to establish a basis for the relevance of angles and nose threat here. Please.
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f-16adf

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Unread post05 May 2019, 23:04

Look at the charts, the Viper at -Ps, for example, say -600 will have a slighly smaller turn radius and higher rate. Even at .6 mach than the F-14. The Tomcat is at 14dps with about 2700ft radius. The F-16 being at about 17dps and about a 2300ft radius.

The F-16 can even get more agressive and hold his aero limit, while decelerating, to where he intercepts Ps=0 at 160KCAS. The Tomcat will never intercept his Ps=0 line at his max lift. He will stall out-
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lbk000

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Unread post05 May 2019, 23:21

I'm trying to explain how to use your dick and you keep talking about dick lengths.

Knock it off.
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fbw

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Unread post05 May 2019, 23:33

Wow, that escalated quickly.
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f-16adf

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Unread post05 May 2019, 23:33

I never tried to make this a rate comparison, those are your words. I was saying that a jet (in this case the F-16 ) can decelerate and hold turn rate across its horizontal -Ps lines, while shrinking its corresponding turn radius. The F-14 pilot (if he chose to decelerate-which would be a dumb move on his part) will also be shrinking his radius, but at the cost of losing more speed and rate. ---Because his -Ps lines ARE NOT horizontal but angle near diagonal. The F-16 has an energy conserving Ps plateau, the F-14 has Ps spikes. So the best move for the Tomcat is to play the STR card. The F-16, hence, has more options remaing in his toolbox.


The fact of the matter is ref. T.O. F-15C-1. Lower right corner, what does it say?
Radius of turn=96.8×KTAS/Rate of turn.

So if we are going to talk slower speeds. For example, one of the reasons why the Hornet has a smaller turn radius than the F-16, is because at mach .6 it has a corresponding better sustained turn rate.


It's called a doghouse plot, because both rate and radius are rather intertwined.

By the way, lose the imature language. It does nothing to buttress your case.
Last edited by f-16adf on 06 May 2019, 00:50, edited 1 time in total.
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jetblast16

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Unread post06 May 2019, 00:32



Rate this! (action starts at 1:41) I like the hover; the filmer did a nice job of zooming out to show perspective above the ground. Sucker just hangs there ... The lift fan sounds like 10,000 vacuum cleaners :shock:
Have F110, Block 70, will travel
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Unread post06 May 2019, 01:22

Thanks - great video of the HOVER. Transition to Mode Four starts at 5:45 to hovering to end with a slow landing at 11:25.
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