PSA: F-14 Performance/FM Development Status + Guided Discussion

[freehand]

1 hour ago, Lurker said:

 

The sarcasm, probably

 

I am aware but who was the comment aimed at pardon the pun. 

[coreyhkh]

so what exactly is wrong with the current flight model ? 

[Raven (Elysian Angel)]

56 minutes ago, coreyhkh said:

so what exactly is wrong with the current flight model ? 

IronMike describes it in the first post of this thread.

[Airhunter]

5 hours ago, coreyhkh said:

so what exactly is wrong with the current flight model ? 

 

Drag for various stores and also at various altitudes is also all over the place resulting in you being stuck at M1.2-ish at roughtly 30k feet and higher, while easily going faster lower). And afaik the B won't hit M2.35-ish anymore clean which was possible in the past.

[Spurts]

From some testing I did in a light B, a max AoA pull at the right speed could hit 30dps at 9G at a weight of 50,000lb at "corner speed" of 325KIAS at sea level.  Based on finding a CLmax of 2.2 at 32deg (taken from the info bar, pegged AoA index in the cockpit)

[Svend_Dellepude]

On 8/25/2021 at 4:06 PM, freehand said:

I am aware but who was the comment aimed at pardon the pun. 

 

Have a read here:

 

 

[Hummingbird]

21 hours ago, Spurts said:

From some testing I did in a light B, a max AoA pull at the right speed could hit 30dps at 9G at a weight of 50,000lb at "corner speed" of 325KIAS at sea level.  Based on finding a CLmax of 2.2 at 32deg (taken from the info bar, pegged AoA index in the cockpit)

 

Sounds about right for that weight, however the speed for it seems a bit low perhaps. 

[Spurts]

12 hours ago, Hummingbird said:

 

Sounds about right for that weight, however the speed for it seems a bit low perhaps. 

Double checked, it was ~31dps at 9G at 318ktas at 44,800lb.  Test point for the CLmax was (info bar) 32 AoA true, 233 KTAS, 330ft, 5.1G, for 23.45dps turn and 2.197CL

[maxsin72]

 

On 8/25/2021 at 10:35 AM, Lurker said:

 

Not only F14 was mach 2.34 capable , it was able to reach mach 2.5. The source is a Grumman test pilot https://www.popularmechanics.com/military/aviation/a27350643/f-14-tomcat/

I hope it would be possible to fix max speed too. 

Edited August 28, 2021 by maxsin72

[Airhunter]

6 hours ago, maxsin72 said:

 

Not only F14 was mach 2.34 capable , it was able to reach mach 2.5. The source is a Grumman test pilot https://www.popularmechanics.com/military/aviation/a27350643/f-14-tomcat/

I hope it would be possible to fix max speed too. 

 

 

Not according to the charts and NATOPS. Was it done with a cleaned up and emty test airframe? Maybe. But this "evidence" is anecdotal at best.

[maxsin72]

16 minutes ago, Airhunter said:

 

Not according to the charts and NATOPS. Was it done with a cleaned up and emty test airframe? Maybe. But this "evidence" is anecdotal at best.

As many know very well, NATOPS charts don't say all about F14, and the witness from a Grumman test pilot is no anecdotal at all. 

Edited August 28, 2021 by maxsin72

[DD_Fenrir]

On 8/28/2021 at 3:12 PM, maxsin72 said:

As many know very well, NATOPS charts don't say all about F14, and the witness from a Grumman test pilot is no anecdotal at all. 

 

 

[maxsin72]

2 hours ago, DD_Fenrir said:

 

What don't you understand exactly? If all about F14 would been on the charts, SME's knowledge wouldn't be necessary, but the truth is we need them very much.

[DD_Fenrir]

 

 

21 minutes ago, maxsin72 said:

What don't you understand exactly? If all about F14 would been on the charts, SME's knowledge wouldn't be necessary, but the truth is we need them very much.

 

If it didn't seem like you'd swallowed the Grumman PR campaign for the F-14 hook line and sinker you're point would be valid.

 

You're so in love with the F-14 (and I get it, I really do) that you point to the flimsiest sources or out of context data to validate your affection.

 

This is why you fail to recognise that your "Mach 2.5" source is the absolute dictionary definition of anecdotal; there is no accompanying data to corroborate, no defining parameters as to how, where and why the aircraft was able to reach these speed.

 

What if the TF-30s were being one-off tested to a limited high power setting to see what stresses they could endure?

What if the aircraft was stripped of pylons and some other drag inducing elements?

What fuel weight was the aircraft at? What about the rest of the airframe? Was a gun fitted, was there even a RIO in the aircraft, or Radar?

What altitude/air pressure/air density was this achieved?

What if all the elements combined to give this?

 

Even then, even if it could make 2.5 under some special circumstance, perhaps there are structural reasons the aircraft shouldn't.

 

[freehand]

On 8/26/2021 at 6:57 PM, Svend_Dellepude said:

 

Have a read here:

 

 

So was aimed at a paying customer nice.

[maxsin72]

3 hours ago, DD_Fenrir said:

 

 

 

If it didn't seem like you'd swallowed the Grumman PR campaign for the F-14 hook line and sinker you're point would be valid.

 

You're so in love with the F-14 (and I get it, I really do) that you point to the flimsiest sources or out of context data to validate your affection.

 

This is why you fail to recognise that your "Mach 2.5" source is the absolute dictionary definition of anecdotal; there is no accompanying data to corroborate, no defining parameters as to how, where and why the aircraft was able to reach these speed.

 

What if the TF-30s were being one-off tested to a limited high power setting to see what stresses they could endure?

What if the aircraft was stripped of pylons and some other drag inducing elements?

What fuel weight was the aircraft at? What about the rest of the airframe? Was a gun fitted, was there even a RIO in the aircraft, or Radar?

What altitude/air pressure/air density was this achieved?

What if all the elements combined to give this?

 

Even then, even if it could make 2.5 under some special circumstance, perhaps there are structural reasons the aircraft shouldn't.

 

 

As i thought, you completely miss the point. It's obvious the F14 reached such that speed in favourable conditions as it's also obvious that at that speed, for example, heat on the canopy could be a big problem. But "shouldn't" does not means it's impossible. The aircraft shouldn't pull more then 7.5 G, more recently 6.5G, but it does not means nobody pulled much more.

It's not a question of "love", it's a question of realism.

[TLTeo]

9 minutes ago, maxsin72 said:

But "shouldn't" does not means it's impossible.

That strongly depends on what configuration that jet flew in. If that configuration is not represented in DCS (much like e.g. the Streak Eagle, which was nothing like your average front line F-15A), then no, it should be impossible. That is completely different from an arbitrary g limit imposed to extend the service life of the F-14 fleet.

Edited August 31, 2021 by TLTeo

[maxsin72]

17 minutes ago, TLTeo said:

That strongly depends on what configuration that jet flew in. If that configuration is not represented in DCS (much like e.g. the Streak Eagle, which was nothing like your average front line F-15A), then no, it should be impossible. That is completely different from an arbitrary g limit imposed to extend the service life of the F-14 fleet.

 

Clean configuration of course, we need only to understand which could be the drag of pylons. Anyway the fact is that now F14 hit a wall at mach 2.2, also diving at full afterburner does not helps. And anyway both of us could be right. Only SME could have the knowledge, the best option would be for HB to contact the test pilot, if possible of course.

[Svend_Dellepude]

4 hours ago, freehand said:

So was aimed at a paying customer nice.

 

Aren't we all paying costumers?

[freehand]

8 hours ago, Svend_Dellepude said:

 

Aren't we all paying costumers?

Yes and your point is ?

Edited September 1, 2021 by freehand

[lunaticfringe]

On 8/27/2021 at 6:10 AM, Hummingbird said:

 

Sounds about right for that weight, however the speed for it seems a bit low perhaps. 

Not really.  9G is available at 3x the speed of a 1G stall; airplane that stalls in the low 90s will have enough lift on the wings to convert to 9G at less than 300 knots.  Problem is then how fast you bleed versus how much the blowers are giving you while trying to pull up to Max CL- what you can instantaneously attain vs. what the airplane can give you in response, etc. Similarly, the level flight DPS attained is correct as well; 318 knots at an entry of 83.6 degrees bank angle (9.0G) is 30.601 degrees per second. 

 

[Hummingbird]

19 hours ago, lunaticfringe said:

Not really.  9G is available at 3x the speed of a 1G stall; airplane that stalls in the low 90s will have enough lift on the wings to convert to 9G at less than 300 knots.  Problem is then how fast you bleed versus how much the blowers are giving you while trying to pull up to Max CL- what you can instantaneously attain vs. what the airplane can give you in response, etc. Similarly, the level flight DPS attained is correct as well; 318 knots at an entry of 83.6 degrees bank angle (9.0G) is 30.601 degrees per second. 

 

Well Clmax changes with the mach number, so I wouldn't say it's entirely that straight forward. As for the 1 G stall speed in the low 90's, that's in landing configuration if I'm not mistaken, so full flaps & slats, which is quite a bit different from the maneuver setting these will be in when in a turn at 0.48 TMN at 50,000 lbs.

 

However at the 44,800 lbs Spurts later mentions, or about 11,000 lbs lighter than the lightest configuration on the available charts, I can see 9 G instantaneous being achieved at as low as 318 KTAS (0.48 TMN). Not at 50,000 lbs though, to hit 9 G at that weight the cat would have to go a bit faster.

 

The baseline here is that at 55,620 lbs and 5 kft, 7.5 G instantaneous is first attainable at ~0.54 TMN (357 KTAS), which means that at SL this would be attainable at around 0.48 mach (318 KTAS). If we then scrape off 11,000 lbs of weight, so that we're at the 44,800 lbs Spurts mentions later,  then 9 G at that same speeds appears entirely reasonable indeed.

 

In short I don't have any reason to believe that HB got the ITR or Clmax vs mach wrong for the F-14. The only issue that I've identified with the FM is in the lack of sustainable rate/load factor (Ps=0), where thrust & drag suddenly become important. Wether it's incorrect thrust or drag that's the culprit however, only the devs know.

 

Edited September 1, 2021 by Hummingbird

[jcdata]

You understand these charts are calculated estimates?

With that said..no one actually tries to get max speed in a flying Tin can near bingo states..

The eagle did with backing from MCD

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[jcdata]

Anyone do time to climb tests specified 9n NATOPS?

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[sLYFa]

I did some time ago. B was pretty good (+/- 10% from the charts), A was pretty off (overperforming in MIL climbs, underperforming in AB)