G limits and Dogfighting

[Southernbear]

On 12/2/2020 at 4:44 AM, Eagle7907 said:

So this topic came up on Discord and I learned something new about this aircraft yet I’m blown away about this limitation.  According to documents, the F-14 is limited to 6.5Gs.  My question is how in the heck do you know you don’t exceed this limitation while dogfighting?  IRL, was this limitation ever complied?  If so, how in a close quarters fight?  I’ve been taught “lose sight, lose fight” and watching a G meter will easily cause this as an issue.

 

Also, does the AI comply with this limit as well?

I've said it before and I'll say it again.

The tomcat doesn't have a G limit...well not the traditional Modern fighter aircraft sense, as it doesn't have a digital flight computer to limit your imput so you can keep pulling till you break something. As this "something" can vary from plane to plane you need a blanket number. From Grumman it was 7.5Gs and then for safety reasons the Navy pulled that down to 6.5. There are documented cases however of planes routinely from the USN reaching 8-9Gs with no issues as well as one unsubstantiated report form an Iranian pilot during the Iran-Iraq war which ended up maxing out the G dial which had a max of 11.5Gs itself, in a dogfight while still being able to fly home. the Pilot suffered knee injuries, the RIO was in a neck brace for a few months and the plane had a total of 9 airframe structural fractures which grounded it for 2 years. But it flew home and didn't fly apart. (According to the allegded story according to Col. Fereydoun A. Mazandarani and his RIO Maj. Shokraee-Fard) 

[Southernbear]

Oh and one more thing, even if you didn't ACTUALLY break anything, the F-14 Gyros for it's INS would be pulled out of alignment with extended G or high G so while your plane itself might be fine after doing 1 too many 9-10G pulls you'd find that your CCIP and CCRP capability as well as your Navigation would either be inaccurate or completely useless.

[Wizard_03]

Just because an aircraft "survives" a high G excursion with or without damage does not mean it can do that every flight for it's service life.

 

Planes like F-15/16/35A are certified for 9G because they can do that every single flight without reducing their service lives. That's what a G limit means. There is zero risk to the jet or it's systems provided it's maintained properly, to do that every single flight up to that number.

 

Huge difference for the F-14. Anything above that documented limit is going to need a fatigue inspection at the least and likely fixes or worse at the most. 

 

 

Edited December 3, 2020 by Wizard_03

[Slant]

21 hours ago, Eagle7907 said:

Oh thanks guys! Wow. Very nice.

So after this discussion, I was curious how “difficult” it would be to knife fight trying my best to not be so sporty in the turns. It seems to be somewhat easy to stay below 6.5. However for situations where you have stores or a higher GW with a lower tolerance, it gets....interesting.


Sent from my iPhone using Tapatalk Pro

 

Here's my logic... if there's a bad dude up my butt trying to kill me, I'll pull whatever G the airframe gives me, regardless of any G-limit imposed by safety guys. If I manage to kill him, I'll fly home and call it a good day. If you have the choice of a) overstressing the airframe in a fight and flying home to listen to the plane captain bitch at you for overstressing or b) breaking the airframe by flying through a cloud of bullets and subsequently colliding with a planet, I'd prefer a).

 

Edited December 3, 2020 by Slant
Forum seems to have double post issues...

[Eagle7907]

Right. I understand, and agree with the capabilities, the decision making. The reason behind the questions was the surprise of a 6.5 limit without any inside knowledge as to the IRL points of view. I mean clearly the airframe can be pushed beyond 6.5. We all have done it ever since HB released the module. I’m not denying that, nor anything at this point, I just wanted more inside information.


Sent from my iPhone using Tapatalk Pro

[Uxi]

On 12/2/2020 at 7:35 AM, Victory205 said:

The F14 suffered from bulkhead cracks (I should know the number of the specific bulkhead station, but can’t recall at the moment) and fuselage delamination.

 

569 Bulkhead?  Supposedly it was high strength aluminum but changed to titanium for new build F-14B and F-14D. 

[Southernbear]

3 hours ago, Wizard_03 said:

Huge difference for the F-14. Anything above that documented limit is going to need a fatigue inspection at the least and likely fixes or worse at the most.

 

Quite often G limits for planes without a electronic G limiter have a safety margin, like 120% or 130%. Considering Grumman found in their testing that the one part of the plane in extended G loading that they were worried about were the wings which didn't break even up to 13.3Gs (at which point the engines ripped out of their nacelles) its safe to say the F-14 has a safety margin applied. 

 

 

 

[Wizard_03]

A safety margin is exactly that. A safety margin doesn't guarantee anything about what the jet absolutely can or cannot do. The limits documented are what the jet can absolutely get away with, and for the F-14 that number is 7.5 and for those other jets I noted it's 9 and you can apply a safety margin for them too if you want. Either way the F-14 is not certified for anything above 7.5 simple as that. 

 

Probably is not the same as yes. The F-14 probably can exceed 7.5 and be fine F-16 doesn't need an asterisk it CAN do 9 no question. 

 

[captain_dalan]

To the OP:
take the anecdotal evidence for structural limitations for what they are, anecdotes. No matter who writes them. Take for example something of my own book. I've been doing endurance running for more then 20 years now. Trail running for the last 7 or so. In that time i've had my share of falls and bruises. Some of those on downhill slopes. 3 years ago i had a particularly nasty one, in which  i rolled for 15ft before i stopped. End result. A few minor scratches from the rocks and gravel. Last year i broke my elbow during a light jogging training. In both cases i fell on my hands (palms).  So what are my structural limits? What is the special case scenario? Did i roll a natural 20 in the first case and was just lucky? Or did i roll a natural 1 in the second case and was just plain unlucky? We can't know. There aren't enough cases in our sample size.

It is the same with over-g in planes. Some people broke them by sneezing at them. Others took them to peg and they were still fine. What we do know for sure is that the plane was designed to routinely be flown at 7.5 which would imply it was safely tested up to 10. But, as we know, production was cut short and thus flight hours had to be extended. Perhaps more then once. By the end of it's service life, some of the birds had over 9000 flight hours on them. This meant that routine ops had to be performed at lower g loads. And further down the service life, the more of hazard higher g excursions  would be.

What's my take on it? Until we have maintenance hours and supply chains in DCS, it doesn't really mean anything. Should you fly her at 6g at all times, or should you peg the meter at 10 is entirely up to you. Every flight you make in DCS is a unique flight and every bird is a unique bird. HB simulates some initial fatigue state, but that state won't transfer to your next mission, so it doesn't really matter. As for online use, birds are available per server slots, not service hours. So again, real life considerations are irrelevant. I do know one thing though....... in a recent interview by a "famous" Youtuber with a legendary F-14 crew member....... when the tuber asked about the g-restrictions and the answer he received (and was totally not expecting it) was that the plane was constantly flown over 8 g and the ground crew didn't make fuss about it........ oh man, the look on that Youtuber's face....... like taking a candy from a baby! Priceless!!!!

[Southernbear]

3 hours ago, captain_dalan said:

..... in a recent interview by a "famous" Youtuber with a legendary F-14 crew member....... when the tuber asked about the g-restrictions and the answer he received (and was totally not expecting it) was that the plane was constantly flown over 8 g and the ground crew didn't make fuss about it........ oh man, the look on that Youtuber's face....... like taking a candy from a baby! Priceless!!!!

Oh I must know where to find this video, theres been so many F-14 interviews over the last year that I don't even know where to start. 

[Hummingbird]

On 12/3/2020 at 10:22 PM, Wizard_03 said:

A safety margin is exactly that. A safety margin doesn't guarantee anything about what the jet absolutely can or cannot do. The limits documented are what the jet can absolutely get away with, and for the F-14 that number is 7.5 and for those other jets I noted it's 9 and you can apply a safety margin for them too if you want. Either way the F-14 is not certified for anything above 7.5 simple as that. 

 

Probably is not the same as yes. The F-14 probably can exceed 7.5 and be fine F-16 doesn't need an asterisk it CAN do 9 no question. 

 

 

The F-15's limit was initially set at 7.33 G, the OWS allowed them to push it to 9 G. Had the F-14 gotten OWS AND full orders, it could've been cleared for 9 G as well. 

[Wizard_03]

2 hours ago, Hummingbird said:

 

The F-15's limit was initially set at 7.33 G, the OWS allowed them to push it to 9 G. Had the F-14 gotten OWS AND full orders, it could've been cleared for 9 G as well. 

 

I mean we can play at hypotheticals all day. In real life it didn't and wasn't. But I doubt that as well because most of the tomcats were all but falling apart by the time they were retired, and that's with a 7.5 and then later 6.5 limit. Whereas many of the eagles were/are in much better shape and vastly exceeded their service lives.

 

In regards to F-15 I also guarantee they had a lot more scientific data to support that decision then sea stories. And just like the tomcat there are also plenty of "stories" about taking it past 9 as well. 

[Hummingbird]

2 hours ago, Wizard_03 said:

 

I mean we can play at hypotheticals all day. In real life it didn't and wasn't. But I doubt that as well because most of the tomcats were all but falling apart by the time they were retired, and that's with a 7.5 and then later 6.5 limit. Whereas many of the eagles were/are in much better shape and vastly exceeded their service lives.

 

Nothing hypothetical about it, the F14 was comfortably a 7.5 G plane without a OWS, the ultimate load limit was even a bit above the Eagles. The reason the cats were so worn at the end are pretty obvious, apart from being used in a far more rigorous environment (salt water, carrier landings etc), they had to last a lot longer than the Eagles as orders were cut way short - the very reason they got a peace time 6.5 G limit. 

 

Wether the Eagles were in better shape at the end of similar flight hours I also seriously doubt, despite the fact that they never were short on parts for these either, and lots of these had repaired airframes.

 

In short, if you're pulling enough G's to break a Tomcat, you're also pulling enough to break an Eagle.

Edited December 5, 2020 by Hummingbird

[Wizard_03]

1 minute ago, Hummingbird said:

 

Nothing hypothetical about it, the ultimate load limit is the same. The reason the cats were so worn at the end are pretty obvious, apart from being used in a far more rigorous environment (salt water, carrier landings etc), they had to last a lot longer than the Eagles as orders were cut way short.

 

Wether the Eagles were in better shape at the end I also seriously doubt, despite the fact that they never were short on parts for these either, and lots of these had repaired airframes.

Another reason they we're so worn is the constant abuse and overloads from ACM practice. The by and far worst birds of the bunch we're the top gun ones which had far less exposure to the ocean. So yeah there's a reason they we're not given an OWS and certified for 9G that goes beyond simple cost.

 

And simply put the Eagles are still around, the costs to extend their lives did not exceed their usefulness unlike the cat. That speaks for it self. New Eagles coming of the line are cleared for 9 all the way up to 20,000 hours vs 7000 for Tomcat. F-14Ds we're not given any such acceptable load increase, when they we're new. So IF they could have extended the envelope, then the question is why didn't they? If the airframes were that sound why didn't they last longer? Why did they break so often? ect. ect.

[Quid]

23 minutes ago, Wizard_03 said:

And simply put the Eagles are still around, the costs to extend their lives did not exceed their usefulness unlike the cat. That speaks for it self. New Eagles coming of the line are cleared for 9 all the way up to 20,000 hours vs 7000 for Tomcat. F-14Ds we're not given any such acceptable load increase, when they we're new. So IF they could have extended the envelope, then the question is why didn't they? If the airframes were that sound why didn't they last longer? Why did they break so often? ect. ect.

Simple, the F-15 was originally slated to be retired ca. 2012 like the F-14 (original planned 2007 for the A, 2008 for the B, 2012 for the D), but its replacement (F-22A) got the axe at 187 planes.  The Air Force HAD to extend the F-15 because it didn't have the numbers to replace it.  The Navy had the F/A-18E/F to backfill the F-14, so the Navy had no reason to perform a SLEP on the Turkey. 

[Wizard_03]

7 minutes ago, Quid said:

Simple, the F-15 was originally slated to be retired ca. 2012 like the F-14 (original planned 2007 for the A, 2008 for the B, 2012 for the D), but its replacement (F-22A) got the axe at 187 planes.  The Air Force HAD to extend the F-15 because it didn't have the numbers to replace it.  The Navy had the F/A-18E/F to backfill the F-14, so the Navy had no reason to perform a SLEP on the Turkey. 

No they absolutely could have done SLEPs on the tomcat (They certainly talked about it) they choose to go with super hornet. That doesn't answer my question either. Because F-15s got OWS and 9G Clearance WAY before 2012. Why didn't the F-14Ds or any other Rebuilt aircraft, when they we're new?

 

Is it really a case of should've, could've, and didn't? Or can't, don't want too, and didn't?

[Wizard_03]

1 hour ago, Hummingbird said:

In short, if you're pulling enough G's to break a Tomcat, you're also pulling enough to break an Eagle.

Define Break? Engines fall out sure that's probably true for both. But does the INS break for the Eagle at 9, do the Bulkheads crack?  Is the aircraft's service life shortened? 

 

9G certification means nothing breaks at 9 and the jet can do that every flight for its full service life. Can the tomcat do that? We don't know. But the eagle can.

Edited December 5, 2020 by Wizard_03

[KL0083]

On 12/6/2020 at 1:56 AM, Wizard_03 said:

Is it really a case of should've, could've, and didn't? Or can't, don't want too, and didn't?

 

Because when those of BC/PC "elites" unleash their puppet to condemn on Tomcat was so-called "obsolete" or less "cost-effective" to public, are not only moving funds in building Enron and Lehman simultaneously but with unlimited enthusiasm and what they so-called "effectivness" . 

 

Simple! 

Edited December 7, 2020 by KL0083

[Hummingbird]

The INS wouldn't break at 9 G, esp. not on a F-14D with newer digital hardware. 

 

As foe newly built F15E's, they're are more resilient as they benefit from substantial advances in metallurgy and other materials since the 70's, increasing strength whilst at the same time saving weight. 

 

The F-14 would've enjoyed the same benefits had it been kept, but a certain "D*ck" didnt allow that, something most Navy officers bemoaned.

 

 

 

 

[Quid]

43 minutes ago, Wizard_03 said:

No they absolutely could have done SLEPs on the tomcat (They certainly talked about it) they choose to go with super hornet. That doesn't answer my question either. Because F-15s got OWS and 9G Clearance WAY before 2012. Why didn't the F-14Ds or any other Rebuilt aircraft, when they we're new?

 

Is it really a case of should've, could've, and didn't? Or can't, don't want too, and didn't?

 

 

I didn't say they couldn't, I said the Navy already had a kind-of replacement available (the SH wasn't ever meant to be a replacement for the F-14, but in the post-Cold War environment, it was perceived to be able to fill the mission well enough), so they didn't have a reason to.  As to why they went with the SH, that's been written about to exhaustion over the past 28 years.  Had they chosen to go with the F-14D or something beyond (ST21, "F-14E," etc.), there may have been a reason to extend the older ones or re-build them into later models (like the F-14D(R) and F-14KB, which did include service life extensions from the basic F-14A they were built out of) but that is all hypothetical.  

 

I did not answer your questions well, however.  

 

"And simply put the Eagles are still around, the costs to extend their lives did not exceed their usefulness unlike the cat."
The F-15's replacement got axed.  It shows that we still need it because we can't replace it.  If the same were true of the F-14, they'd still be flying as well, but post-Cold War leadership chose a different path.

 

"New Eagles coming of the line are cleared for 9 all the way up to 20,000 hours vs 7000 for Tomcat."

After airframe modifications, sure.  The F-15 was originally rated for 4,000 hours.

 

"F-14Ds we're not given any such acceptable load increase, when they we're new."

The F-14B/D did have an appreciable load increase, actually - if you check the -1.1, the aircraft have an extended symmetrical load limit out to 55,585 combat weight (contradicting the -1, interestingly enough), while the "A's" is lower.  That said, all Navy aircraft have lower g limits than Air Force, and it's no wonder: catapult assisted take-offs at high weights, arrested landings and saltwater environment leading to increased fatigue, etc. 

 

"So IF they could have extended the envelope, then the question is why didn't they?"
Ask the Navy.

 

"If the airframes were that sound why didn't they last longer?"
They lasted as long as they needed to until replacement.  The F-15's SLEP to 18,000 or 20,000 (whatever your source) didn't start until 2011 when it was clear the F-22A wasn't ever getting its production lines restarted and that the F-15 was going to have to stay for the foreseeable future.  Rebuilt F-14s did see life extensions.

 

"Why did they break so often?"
Not sure what you mean here?  Every fighter breaks, every fighter requires maintenance, and even newer aircraft are consistently "broken".  Hell the Super Hornet's operationally ready rate between 2017 and 2018 was uner 50%.  Why are they breaking so often?  Why are they always down?  Even those "operationally ready" are not necessarily fully mission capable, certain systems and subsystems may be bent, but it can still do most of or certain missions.  This is also true for the F-15.

[Wizard_03]

1 hour ago, Quid said:

 

 

That said, all Navy aircraft have lower g limits than Air Force, and it's no wonder: catapult assisted take-offs at high weights, arrested landings and saltwater environment leading to increased fatigue, etc. 

 

Ask the Navy.

Bingo. All Navy fighters are rated at 7.5 for good reasons. So lets it too bed, can the F-14 pull 9? sure, did it operationally? Occasionally. Even without consequences? Yes. SO Is it best practice to take the jet passed 7.5? Nope. Is the airframe certified for 9G like F-15/16/35A/whatever? Nope.  Could it have been? Maybe, Probably, but not without a dedicated SLEP with specific airframe structural reinforcement.

 

Did any of that happen? Nope.

 

You can do whatever you want in the sim, but the real tomcat was limited 7.5Gs and pilots were expected to abide by that limitation in ACM/BFM.  Which was the OPs question. All sea stories and Hypothetical armchair aviation aside. 

 

Edited December 5, 2020 by Wizard_03

[Quid]

3 minutes ago, Wizard_03 said:

Bingo. All Navy fighters are rated at 7.5 for good reasons. So lets it too bed, can the F-14 pull 9? sure, did it operationally? Occasionally. Even without consequences? Yes. SO Is it best practice to take the jet passed 7.5? Nope. Is the airframe certified for 9G like F-15/16/35A/whatever? Nope.  Could it have been? Maybe, Probably, but not without a dedicated SLEP with specific airframe structural reinforcement.

 

Did any of that happen? Nope.

 

You can do whatever you want in the sim, but the real tomcat was limited 7.5Gs and pilots were expected to abide by that limitation in ACM/BFM.  Which was the OPs question. All sea stories and Hypothetical armchair aviation aside. 

 

I agree with you 100% here.

[Hummingbird]

All it needed to be certified for 9 G would be full orders, OWS and land based. No airframe reinforcement was necessary, the thing was already tougher than the F-15's until they were extensively modified in the 2000's with new tougher materials.

Edited December 5, 2020 by Hummingbird

[FWind]

8小时前,Wizard_03说:

Bingo. All Navy fighters are rated at 7.5 for good reasons. So lets it too bed, can the F-14 pull 9? sure, did it operationally? Occasionally. Even without consequences? Yes. SO Is it best practice to take the jet passed 7.5? Nope. Is the airframe certified for 9G like F-15/16/35A/whatever? Nope.  Could it have been? Maybe, Probably, but not without a dedicated SLEP with specific airframe structural reinforcement.

 

Did any of that happen? Nope.

 

You can do whatever you want in the sim, but the real tomcat was limited 7.5Gs and pilots were expected to abide by that limitation in ACM/BFM.  Which was the OPs question. All sea stories and Hypothetical armchair aviation aside. 

 

Spectrum in report

 

5小时前,Hummingbird说:

All it needed to be certified for 9 G would be full orders, OWS and land based. No airframe reinforcement was necessary, the thing was already tougher than the F-15's until they were extensively modified in the 2000's with new tougher materials.

https://forums.eagle.ru/topic/254416-g-limits-and-dogfighting/?do=findComment&comment=4498077

 

[Quid]

Just an addendum to this - I've received a copy of the 1 November 1975 F-14A NATOPS; the F-14's g-limit was already 6.5g symmetrical out to 49,548lbs at that point (the date of the chart is 1 November 1973); note the aircraft was lighter at this time with a gross weight of 40,070lbs; combat weight would have been about 51,200 lbs (60% fuel, 2x Sparrow, 2x Sidewinder, gun).  The biggest differences I notice in this from later volumes is that the early F-14A appears to have had a lower g-limit if the maneuver flaps were extended at this time: 5.5g out to 49,548lbs, and then descending (akin to the chart Victory205 posted) which was eliminated later on.  As I wrote earlier and as just about everyone here is aware, the original design requirement was 7.5g, but if the date on the chart is correct (1973), it would have been the same in the first published operational NATOPS from 1 June 1974, and the Tomcat never actually had that higher limit operationally.

 

And yes, I'm well aware and have posted even in this thread that Tomcats have managed to get back unscathed with over 12g, etc., etc., but in line with OP's question and the discussions hereafter, the official NATOPS limit appears to have been 6.5g symmetrical to just under combat weight since fleet introduction.

Edited December 8, 2020 by Quid