F-35 and Airshows

Discuss the F-35 Lightning II
  • Author
  • Message
Offline

lbk000

Senior member

Senior member

  • Posts: 260
  • Joined: 04 May 2017, 16:19

Unread post06 May 2019, 02:40

f-16adf wrote:It's called a doghouse plot, because both rate and radius are rather intertwined.

I've been trying to avoid engaging you on the F-16 vs F-14 comparison because the topic I was addressing is aircraft-agnostic as they're general BFM concepts. You don't seem to want to understand this.

But since you are looking for a chart fight, let's go.

f-14a_dh.png
f-16c_dh.png

These are the most relevant charts I have on hand, as you can see, the preference goes to the F-16; the F-14 chart isn't even for the B/D model which would push the low end out even more.

F-14 sustained minimum radius is somewhere down at 1750' @ M0.3; it enjoys <2000'ft radius from M0.4 all the down to M0.2. It's got a bit more unsustainable performance beyond it if you really needed to squeeze it in.
F-16 sustained minimum radius is just a hair under 2000' @M0.34. At M0.4, radius is up at ~2250'.

I don't even know where I'm going with this to be honest. I don't want to prove the F-14 is somehow a "better" aircraft than the F-16, because I think it isn't. But if you were an F-14 pilot, how would you try to win? Because you're not going to rate better than this F-16 if you go up the speed ladder.

How does the mantra of "speed is life" apply for the angles fighter? Riddle me this.
The answer is that it's not something to be taken literally. Speed here does not literally mean that you want to be smashing along as fast as you can go all the time. And your whole "F-16 has better performance" is an utter non-sequitur to this point.
Last edited by lbk000 on 06 May 2019, 03:16, edited 1 time in total.
Offline

f-16adf

Forum Veteran

Forum Veteran

  • Posts: 686
  • Joined: 19 Dec 2016, 17:46

Unread post06 May 2019, 03:14

ERROR NUMBER 1: Comparing a 5,000ft F-14 EM diagram to a 10,000ft F-16 EM diagram.

ERROR NUMBER 2. THE F-14 is at 50% fuel, the F-16 is at nearly 60% fuel.

ERROR NUMBER 3: An F-14 at .3IMN, and 10,000FT will be at basically TPA speeds. The F-16 at .3IMN and 10,000FT will be at PS=0 about 160KCAS IF HE SO CHOOSES TO BE (An F-16CJ with 50% internal fuel).

ERROR NUMBER 4. I never mentioned the term sustained anything, what I did mention was that most people don't understand "sustainability" vs "deceleration".
Offline

lbk000

Senior member

Senior member

  • Posts: 260
  • Joined: 04 May 2017, 16:19

Unread post06 May 2019, 03:26

Nice, you got me there with the altitude.

No, fixing it doesn't make your situation better:
f-14b_dhnf.png

Now this is the B model with the F-110s, but without slats out! Under 2000' radius @ <M0.4 nevertheless. Ouch!

Fuel's not a good point to pick a bone on, it's an apples to oranges comparison. I guarantee you though, dropping 10% gas in the F-16 won't magically tilt the radius in its favor.

What's your deal dude? Why are you so bent out of shape over this? I'll humor you and go back and replace F-14 with F-16, it's cool, it won't change the point I was trying to make.
Offline

f-16adf

Forum Veteran

Forum Veteran

  • Posts: 686
  • Joined: 19 Dec 2016, 17:46

Unread post06 May 2019, 03:35

Try posting a F-14B 10,000ft chart. You posted another 5,000ft chart.


And yes, an F-16CJ at 50% fuel (4 Aim-120, 2 Aim-9 and a DI of 42 and at 25,300lbs) will see its turn rate go up by approx. .4dps maybe slightly more against a F-16CJ with 60% fuel,at 26,000lbs, and a DI of 50. That is why the Average Change in Turn rate diagram is provided in the upper left corner. Hint, hint, the F-16CJ at that load-out and 50% internal fuel is at 25,300lbs, because its actual empty weight is 19,261bs empty and not 20,000lbs empty (do the math). If you want to lose the 2 Aim-9 on the F-14, turn rate only goes up by approx .15dps.

Also the F-16CJ 26,000lbs DI 50 chart never mentions any specific loadout. You can achieve those same numbers with a small A-G load.



See, once again, you are only looking at Ps=0 (i.e. sustainability whether rate or radius). Look at the -Ps lines above that, that represents deceleration.
Offline

lbk000

Senior member

Senior member

  • Posts: 260
  • Joined: 04 May 2017, 16:19

Unread post06 May 2019, 03:44

You're right, I was too hasty about posting up the new chart (again):
f-14b_dhnf.png

It doesn't matter what, the F-14's minimum radius capability is good. Slats will once again make radius its one redeeming metric.
Offline

f-16adf

Forum Veteran

Forum Veteran

  • Posts: 686
  • Joined: 19 Dec 2016, 17:46

Unread post06 May 2019, 03:50

I'm in the Great Lakes and it is now nearly 11pm, and have to go to work tomorrow.



So I am going to leave you with this: It's posts by JBGator (who has flown the F-16 for over 23 years, and is a fighter pilot of 25 plus years).



JB does the absolute BEST job of explaining on how to read an EM diagram, and also deceleration aka -Ps.


viewtopic.php?f=2&t=26829&p=296429#p296429


AND

viewtopic.php?p=387607#p387607
Offline

lbk000

Senior member

Senior member

  • Posts: 260
  • Joined: 04 May 2017, 16:19

Unread post06 May 2019, 04:55

There's really nothing to be combative about here, everything jbgator says is in line with what I've been saying as well. It's just that what you want to talk about is completely different from what I want to talk about. If you think I'm trying to make a point that the F-14 is somehow a better fighter because it's the better groveller, put it out of your head. I cited the two aircraft that were particularly prone to grovelling because grovelling is the most extreme illustration of radius exploitation.

All I want to do is to drag this mess back to a semblance of topical relevance in regards to how to interpret the F-35's performances:

1. High G's do not necessarily accompany every maximum performance point: You can see in the F-14 chart, instantaneous minimum turn radius can be effected at 2.5G's. The F-16's minimum turn radius can be effected at a mere 2G's. You're also floating really slowly in the air. This is usually made up for the fact that on the inside, every knot and degree you have is worth more than the outside guy's because of the truncated path distance. With its excellent low speed authority, the F-35 can generate a lot of turn with very little radius, making it rewarding to enter the low speed portion of the envelope.

2. If speed is life, then acceleration is the fountain of youth. Moving to the right on the doghouse is harder than moving leftwards, and some aircraft are particularly bad at it. The art of energy conservation is one of figuring out how to move rightwards without getting yourself killed in the process -- or at the bare minimum, and awareness of just how much more room remains on the left side of the doghouse and how many chances you have at making a energy-costly play. The F-35, thankfully, has excellent acceleration characteristics, which means it's a lot more mobile than something like the Hornet for moving back towards the right side of the doghouse. It gets to dunk on the profits of low speed low radius, but be gone before getting slapped by the taxes.

3. There's a doghouse inside the doghouse. Having a big doghouse looks good until you realize you are always stuck in one end of it. If you're bad at decelerating, you can wind up stuck on the right side and missing a lot of positional opportunities when the other guy is down left of you and your radius is always just a little too big. If you're bad at accelerating, you can also get stuck on the right side, because you're scared that it's a one way trip leftwards. Your effective, immediately usable performance envelope is smaller than what the chart says, because its shape and size is based on your ability to gain and lose energy. The better your capability of doing so, the bigger and less lopsided this "local envelope" is. This is how the F-35 can pull out "hidden" maneuverability that is not outwardly obvious from the doghouse shape alone.
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 23157
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post06 May 2019, 11:13

F-35B VMFA-121 Hover MCAS Iwakuni May 2019 Air Show: https://www.youtube.com/watch?v=LuMTT6IWOr0

RAN FAA A4G Skyhawk 1970s: https://www.faaaa.asn.au/spazsinbad-a4g/ AND https://www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/
Offline

optimist

Forum Veteran

Forum Veteran

  • Posts: 982
  • Joined: 20 Nov 2014, 03:34
  • Location: australia
  • Warnings: 1

Unread post06 May 2019, 12:59

Give it up sunshine, The last I heard f-16adf was a pilot. They do this stuff in their sleep and can tell you this stuff off the top of their head.
The last time I saw someone try and school a pilot. It was some kid telling alfakilo, why he was wrong about the A-10.
Aussie fanboy
Offline

f-16adf

Forum Veteran

Forum Veteran

  • Posts: 686
  • Joined: 19 Dec 2016, 17:46

Unread post06 May 2019, 19:23

Speed is Life because jets do not initially or typically hit the merge at slow speeds. Generally merge speeds are around 400-450KCAS. For instance one poster has previously stated that F-22 pilots did initially get in trouble because they: "The F-22's that have been "killed" or "gunned" in DACT... it has been written by the more experienced pilots they died when the young hotshot studs became enamored with thrust vectoring, which implies low speed cornering." That is true.

In that well published "AdA Rafale guns F-22 video" notice when the French pilot said "fights on" his air speed was at 423KCAS and about 20,000ft altitude. The Rafale pilot was technically fighting against a jet that has no AOA limit (and even better low speed capability than the F-35), yet he still entered at a speed above 400knots. Which tends to support the statement "Speed is Life". He did that because he is using his speed to trade for angles. And as he bleeds further airspeed, his turn radius gets smaller. Yet, isn't the Rafale an inferior low speed jet to the Raptor? It is limited to about 29.9 degrees of AOA. So obviously the Raptor in theory should be able to create superior angles at certain air speeds. Consequently, low speed high AOA maneuvering is a double edged sword. And if any jet can "recover" quicker from those mistakes (high alpha energy bleed) it is the Raptor. The Rafale pilot was not dumb, he knew what he was fighting, and he handled it. I'm not saying that all his kills were in parameters, most probably not. Yet, he clearly had the F-22 in his HUD.


The whole F-14 v F-16 EM chart was used because those charts are the only official diagrams (NATOPS and USAF T.O.) out there that show actual P-sub-S lines. They are not "flight modeled" but the real deal. The F-16 has more available G, less -Ps energy bleed, so he technically has more options. And as I previously stated, he can hit 9G instantaneously at 10,000ft (while obviously not being able to sustain it) yet he can trade that speed (and G) for angles as he decelerates across his horizontal Ps lines to 6G and further shrink his turn radius. Decelerating from 9G to 6G while holding basically an average turn rate of slightly above 17dps, and a turn radius that initially starts at 3,200ft down to a little over 2,000ft.


F-35 E-M Chart.png


I believe this is a flight modeled F-35A diagram for probably about 20,000ft. Notice the airspeed limit at slightly above 1.4 Mach, and also take note that at 8.5G his Ps are at -2,500. So he is probably at 20Kft most likely. Don't know fuel or armament. But, the F-35A, since he has 9G capability, can enter the fight at .85 mach (slightly over 400KCAS) initially at 9G and a turn radius of approx 2,900ft, decelerate across that -1500Ps line all the way down to about 6G with a turn radius shrinking down to just above 2,000ft. All the while he is holding a turn rate of about 17dps.
Last edited by f-16adf on 06 May 2019, 19:52, edited 2 times in total.
Offline
User avatar

marsavian

Elite 1K

Elite 1K

  • Posts: 1208
  • Joined: 02 Feb 2018, 21:55

Unread post06 May 2019, 19:46

Regarding the Rafale/F-22 video encounter, both aircraft bled their energy levels to very slow speeds and the Rafale remains very directionally controllable at these speeds which allowed it to counter the high AoA ability of the F-22. Getting back to the F-35 it can pull 9g from transonic and at the end of the energy bleed then pull another 50 degree nose angle and if that hasn't worked go straight into a climb to change its plane of direction. This does not sound like the helpless baby seal all its critics were trying to claim but an aggressive pointy energy fighter.
Offline

f-16adf

Forum Veteran

Forum Veteran

  • Posts: 686
  • Joined: 19 Dec 2016, 17:46

Unread post06 May 2019, 19:53

Yes, but what speed did the Rafale begin at? 423KCAS. So speed is life in this instance.



When I imply "Speed is Life" I am generally referring to initial merge speeds. Sorry, but ACM merge speeds do not begin at 250 or 300KCAS, hence, you would bleed down even further. And if you begin that slow, you are probably going to lose.
Last edited by f-16adf on 06 May 2019, 20:47, edited 1 time in total.
Offline

SpudmanWP

Elite 5K

Elite 5K

  • Posts: 8385
  • Joined: 12 Oct 2006, 19:18
  • Location: California

Unread post06 May 2019, 20:14

"Speed is life" is on it's way out. It only applied to previous generations of fighters because sensor & weapon tech of the time virtually mandated that combat start at the merge. GW1 ushered in a new era of combat, on national TV, where weapons and information took center stage.

It was Lt Col Burke (USMC Ret) who said

"The F-22 is the fastest, the most powerful fighter ever built. The least impressive thing about the Raptor is how fast it is, and it is really fast. The least impressive thing about the Raptor is its speed and maneuverability."


He also said

The old Top Gun fighter pilot mantra that “speed is life, more is better” had been replaced by “information is life, more is better”. “Information is far more valuable than speed,” he said. “The F-35 has no peer in terms of information dominance and the sharing of that information.”
"The early bird gets the worm but the second mouse gets the cheese."
Offline

f-16adf

Forum Veteran

Forum Veteran

  • Posts: 686
  • Joined: 19 Dec 2016, 17:46

Unread post06 May 2019, 20:27

As far as F-35A vs the F-35C. Most likely, the C model (because of the nature of its wing) has a superior STR from .4-.68IMN (lower speeds) and a smaller turn radius. Now if the F-35C's STR peaks at .68IMN, then after, it should be on the way downwards (including all its P-sub-S lines). All the while the F-35A's STR is still increasing to approx .82IMN. Now if both jets hit the merge at say 400KCAS, the F-35A should have an advantage because of his extra G. Like the F-16 v F-14 example (and if this F-35 EM diagram is true) the -35A should decelerate with less energy loss vs the C model. It also has a superior thrust advantage against the F-35C. Now the big question is if you had actual EM F-35A and F-35C charts it would be very interesting to see how those P-sub-S lines overlay. Who has the advantage- at what speed- and the quantity of that advantage.

That remains a big unknown.
Offline
User avatar

marsavian

Elite 1K

Elite 1K

  • Posts: 1208
  • Joined: 02 Feb 2018, 21:55

Unread post06 May 2019, 21:16

That F-35 E-M graph was estimated to be around 19kft based on the speed.

viewtopic.php?p=397217#p397217

The ITR/Min Radius is better than a F-16 at that altitude with STR just a little less but it bleeds more energy in that instantaneous state.

Image
PreviousNext

Return to General F-35 Forum

Who is online

Users browsing this forum: No registered users and 15 guests