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Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 16:52
by gta4
http://m.aviationweek.com/defense/podca ... 645d23cd46

It took F35 only 3 seconds to completes the 135 deg hard turn. The average turn rate is 42deg/sec So the peak turn rate is higher than 42deg/sec.

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 17:12
by sprstdlyscottsmn
Oh boy.

First, he also says he is at 50 degrees AoA. Subtract that from the 135 degrees and it drops to a transient turn rate of 28+ degrees per second. Nothing to sneeze at. Due to where that maneuver is in the demo we can also assume that is ~50% fuel remaining. We don't know G involved, but from what I have seen even 9G aircraft don't go over ~7G in the routine.

And watch the video, the nose rakes very quickly (~3s) and then seems to stabilize before he goes vertical, this is holding the nose position while AoA decreases, i.e. flight path continues to change.

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 17:17
by f-16adf
Is this the maneuver in question (Dojo Drift) at 9:19 of this vid?

https://www.youtube.com/watch?v=8WOOmbMFA5A


If so, he is coming in as it seems under (or well under) 300knots. (slow speeds)

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 17:30
by gta4
sprstdlyscottsmn wrote:Oh boy.

First, he also says he is at 50 degrees AoA. Subtract that from the 135 degrees and it drops to a transient turn rate of 28+ degrees per second. Nothing to sneeze at. Due to where that maneuver is in the demo we can also assume that is ~50% fuel remaining. We don't know G involved, but from what I have seen even 9G aircraft don't go over ~7G in the routine.

And watch the video, the nose rakes very quickly (~3s) and then seems to stabilize before he goes vertical, this is holding the nose position while AoA decreases, i.e. flight path continues to change.


If you want To throw the 50deg aoa you also need To throw the time consumed To pull 50 deg AOA, which Will not shrink the turn rate that much. We can Only assume 28deg+deg/sec.

And that is average turn rate within the 3 second interval, not the peak turn rate.

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 17:34
by f-16adf
At the speed he is approaching the field in that maneuver, (300KCAS or lower) basically low speeds. There is no way that is a 9G pull. Maybe 6-7G ish. But you would certainly need more speed for 9G. Something on the order of 350KCAS if not more?



The first part of that pull is similar to the initial pull of the F-22's Hoover Pitch (Stiff Pitch) which is flown at 300KCAS.

If so, that is not at the jet's corner speed, which is defined as the lowest speed to generate maximum structural load (9G in this case for the F-35) and also referred to as ITR.


F-22 Stiff Pitch at 13:40
https://www.youtube.com/watch?v=uQy1S_Rw4wM



Any thoughts on this??

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 18:21
by sprstdlyscottsmn
ITR is any transient change in the flight path. You are looking for the definition of Peak ITR, but otherwise you are correct.

Lets look at the maneuver and what is stated. The nose is pointed 135 degrees in 3 seconds. We will use 3.00s for the sake of this discussion. By the time the nose as moved that much the AoA is 50. This means the flight path as moved 85 degrees in 3.00s.

I agree with your assessment f-16adf that the entry is likely ~300KCAS and 7G, not the conditions for peak ITR. The transient turn rate averages 28.3dps. It could even be, very nearly, constant 28.3dps, and here is why. AoA does not increase instantly, so the turn rate has to ramp up as AoA ramps up. Speed is already dropping and with it the ability to turn. We hit max lift AoA and presumably exceed it. We don;t know all the nitty gritty details about pitch onset rates (and we have no right to) but what could very well be happening is that the lift quickly (~.5s) build to a 20dps turn, peaks around 32dps at 270?KCAS and 6?G and settles around 26dps at 50AoA all in the span of 3s.

We don't know.

What CAN be taken from this is that when around 50% internal fuel (admittedly my guestimation) at "sea level standard" the F-35A can generate transient turn rates in excess of 28 dps even below corner velocity.

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 18:23
by f-16adf
Thanks for the kind reply Spurts!

Either way, that's a pretty awesome move for that jet.

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 18:36
by sprstdlyscottsmn
it's an awesome move, period. Huge energy bleeding turn, has enough control to maintain a modest climb as AoA reduces and then has the power to go into a 50-70 degree climb (perspective makes it LOOK vertical).

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 18:51
by sferrin
f-16adf wrote:F-22 Stiff Pitch at 13:40
https://www.youtube.com/watch?v=uQy1S_Rw4wM



Any thoughts on this??


Don't know what's more impressive, that one or this one here at 2:42. They're slightly different.


Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 18:54
by sprstdlyscottsmn
so that looks like the same maneuver as the "Dojo Drift" performed by an aircraft that makes more lift and has more thrust. Maybe it needs to be called the Dozer Drift?

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 20:10
by doge
Of all I have ever seen, The most Intense instantaneous turn of F-35A is...This, Rhode Island Air Show video by Luke AFB itself.
@0:53~ (short. in a flash.)

(9 months ago, I wanted to see another angle video of this turn, I searched on the Rhode Island Air Show on Youtube,Twitter,Facebook,Instagram,etc and saw so many videos..... After all, I remember that I can't find it and everything was ended in vain....... :( :cry: )

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 21:34
by spazsinbad

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 22:02
by quicksilver
“By the time the nose as moved that much the AoA is 50. This means the flight path as moved 85 degrees in 3.00s.”

Yes, but theta has moved 135 degrees, which in practical application (bfm), is often more relevant/useful. Of course, e.g. if one is trying to save one’s **** in a pull out from something nose low and heading for the dirt, the flight path remains more relevant. :wink:

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 22:50
by wrightwing
sprstdlyscottsmn wrote:We don't know.

What CAN be taken from this is that when around 50% internal fuel (admittedly my guestimation) at "sea level standard" the F-35A can generate transient turn rates in excess of 28 dps even below corner velocity.

It's hard to know the weight for sure, as the routine started at full fuel.

Re: Official declassifies F35's instantaneous turn rate

Unread postPosted: 04 Apr 2019, 22:53
by sprstdlyscottsmn
Yeah, and the routine is toward the end, and they have reserve requirements of not less than 13%