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Max G-Force sustained at g-LOC

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7 hours ago, VO101Kurfurst said:

Indeed this feature was appearantly copied after comparison flights of Hurricance against the 109E in May 1940 which revealed the seating positions importance in increased G resistance.

 

 

This raises an interesting question. Did Willy Messerschmitt chose the pilot's seating posture for G resistance, or was this just a fortuitous consequence of trying to keep the fuselage frontal area as small as possible?

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13 hours ago, AndyJWest said:

 

This raises an interesting question. Did Willy Messerschmitt chose the pilot's seating posture for G resistance, or was this just a fortuitous consequence of trying to keep the fuselage frontal area as small as possible?

 True, but imho, if there is an advantage for the pilot, the real issue, tactically wise, is to know if it is modeled, and to model it if it is not.

 

And this for all aircraft. Anyway, it is rare that in a WW2 fighter the pilot has a completely vertical seating posture anyway, it is not like this at all. It is a matter of few degrees,  the difference may not be that huge imho. But as you said we need figures and a study.

 

Also, the comparison with only one type only tells us the BF had a "possible" advantage vs the Hurricane.

 

But is it really an advantage a pilot could exploit tactically? Reading the report Kurfurst sent, it seems that in a dogfight there was nothing other than half rolling and diving away that could save the Bf109 from the Hurricane (!?) and that the Bf109 had great difficulties, even using the ("extremely heavy" )trim wheel to go out of the dive. (BTW I would never have expected such a report to be posted by a Bf109 dedicated fan like Kurfurst!!😲!!)

 

Perhaps the Hurricane pilot was able to pull more Gs due to better control authority at higher speeds than the 109 one, this causing the Black out, or the more heavy BF controls allowed its pilot to ride the grey veil to the limit, the report doesn't tell.

 

 

 

 

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On 1/23/2020 at 1:10 PM, VO101Kurfurst said:

Indeed this feature was appearantly copied after comparison flights of Hurricance against the 109E in May 1940 which revealed the seating positions importance in increased G resistance.

 

It is regrettable overlook that this feature of increased g resistance is currently only modelled for USAAF aircraft. 

 

 

On 1/23/2020 at 2:35 PM, Aurora_Stealth said:

What seems to be the underlying question is.. could there be a mechanic simulating G tolerance based on the pilot's relative position and not only a mechanic limited to generic pilot physiology and a separate one for G-Suits. However this alone would be a pretty big undertaking.

 

Adding the G-Suit (new feature) understandably has raised questions about how accurate the other factors are in relativity affecting G force. This is just the natural development of the game and with new features like pilot physiology and G-Suits being simulated.. other significant factors in turn are now under more scrutiny. 

 

However we should be thankful for what we have which is already a huge advancement from the past. I don't think we can realistically demand our much overloaded developers to assess this in the short-term (perhaps a consideration for later development).

 

All other human factors being even (pilot general health, weight, fitness level), you could add a factor like:

 

(Generic G-force application x Relative angle of pilot seat to A/C centreline) - G-Suit factor = Applied G force

 

Yes - I've oversimplified but you get the point.

 

This may (?) in fact be modelled already.

 

Read this thread from the linked post on (concerns unexplained differences in onset of blackout in 109s V allied aircraft)

 

Edited by kendo

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Seems all like conjecture on that Blackouts thread if I'm being honest.

 

The notion of each aircraft's seating position being calculated in the game seems remote - especially as it has never been mentioned by the developers. I'd expect that the game sets a given G-force as a universal blackout limit for every pilot (plus a factor added for G Suits), and the aircraft's angle of bank and speed/acceleration determining how soon that is reached.

 

As the Spitfire and Tempest (mentioned on that Blackouts thread) can (I believe) typically pull more G's at higher speeds - its no surprise an eager pilot blacks out in them sooner when trying to pull hard. In fact because you can't apply more G's as easily and the controls stiffen in the '109 with speeds over ~300/350mph... this mechanically and inadvertently delays that same G force onset.. even if this may only be a fraction of a second slower to lose consciousness.

 

It may just be long enough for a pilot to react in letting off pressure from the stick rather than a more sudden blackout and not being able to react soon enough. It also doesn't help that tactics dictate a Tempest typically wants to keep up more speed up to control the fight and can accelerate faster in the dive which combined with higher G's in a high speed turn.. gives a quicker onset of the blackout.

 

A great number of pilots especially late in the war mentioned that they watched aircraft lose control during maneuvering and occasionally spin out of control but finding an anecdote about a Bf 109 spinning (stalling or buffering - yes) due to maneuvering combat is as rare as gold, and similarly during Battle of Britain - 109's still caught out a surprising number of Spitfire's in turns including in RAF/RAE comparative tests. The reason? well on paper the theory says you can pull X number of maximum G's in an airframe but practicality says that the G force you can actually handle as a person - especially with new and combat inexperienced pilots would be a significant enough factor to reverse certain close matched situations. This has also been described by modern day pilots, so anything that can be done to improve pilots resistance could and did even the odds - because you are getting more performance out of the pilot with the same airframe.

 

This is Rick Volker, aerobatics pilot who flew a Bf109G a few years back. Interesting read about tolerance to G's in the '109, the cockpit and how he was able to keep on maneuvering apparently against aircraft that should not be able to theoretically outmaneuvered in such situations. Obviously he's very experienced - but the insight is intriguing.

https://www.warhistoryonline.com/guest-bloggers/newly-restored-messerschmitt.html


It's hard to say if Messerschmitt deliberately designed the seat in mind for G tolerance - he first designed gliders and wanted a very small frontal profile, in other words its drag to be absolutely minimal to maximise performance - like with gliders. Note the seating position is very, very flat in most gliders but its not really for pulling G's its really for aerodynamic efficiency, hence Messerschmitt did not want a bubble canopy or anything like that which obstructed airflow outside the actual fuselage lines. Whether or not his flying experience or his test pilots experience played a part in knowing about this is unclear.

 

Anyway, only the Dev's can say for sure how their G force calcs work, only they know really what's going on in the code.

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In my personal opinion based on talking to lots of F-16 pilots their G-suit only adds about 1 G, so I'd be very sceptical of the idea that the very first G suits giving a 2-3 G advantage, esp. since not even the modern Libelle suits add that much. 

 

Infact I'd be very surprised if the WW2 G suit added even 1 G of extra max tolerance, and would be very interested in any data to back that up. The fact that modern G suits generally don't add more than 1 G of tolerance is quite telling IMO.

 

Thus IMHO this needs to be looked into, and I have no preference for any side.

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There  is a difference between: oscillating and sustaned lateral acceleration G.

 

The G suit needs to be inflated in order to be effective (and that takes some time). That means it will work only if the G forces are added gradually. If the G forces are added relatively quickly the inclined position of the seat has a bigger effect, together with the G strain maneuver  (anticipation and the special breathing technique).

 

That would mean in high G instanatious turns the 109 has to have initial advantage and not the p 51. At high speed the G forces can be reached faster than the G suit is able to react. The G valve controls the rate of inflation and the action is not instantanious, pressure increases linearly with acceleration at around 8.6 kPa (1.25 psi) per g in UK aircraft [(10.3 kPa or 1.5 psi per g in the USA) - inrelative modern G suits.  That is why liquid filled G suits have an advantage over the inflatable one,  in my opinion.

 

The p 51 pilot would have minor advantage at moderate G when the Gs are sustained. 

The current situation when the P51 has an advantage no matter what is not acuratel  and should be corrected.

 

Edited by JG27_Kornezov
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On 1/19/2020 at 1:58 AM, JG7_X-Man said:

 

The P-51 pilot can pull 8Gs vs the 6Gs of the K-4 pilot before blacking out - Is there 1944 data that backs up this difference ? Or an extrapolation based on present day suit data. I did several studies and this varies quite a bit b/w aircrafts. Not asking anyone to divulge any trade secrets - but can I get a general idea why all pilots don't black out at the same G-load? Then the aircraft that have G-suit hard coded, why was this approach taken - verse a mod.

Found this and already posted it in a similar thread. Seems like those G suits were very efficient:

 

The instructional film warns the pilots that if they now are able to sustain more G, their aircraft may not.

1 hour ago, JG27_Kornezov said:

There  is a difference between: oscillating and sustaned lateral acceleration G.

 

The G suit needs to be inflated in order to be effective (and that takes some time). That means it will work only if the G forces are added gradually. If the G forces are added relatively quickly the inclined position of the seat has a bigger effect, together with the G strain maneuver  (anticipation and the special breathing technique).

 

That would mean in high G instanatious turns the 109 has to have initial advantage and not the p 51. At high speed the G forces can be reached faster than the G suit is able to react. The G valve controls the rate of inflation and the action is not instantanious, pressure increases linearly with acceleration at around 8.6 kPa (1.25 psi) per g in UK aircraft [(10.3 kPa or 1.5 psi per g in the USA) - inrelative modern G suits.  That is why liquid filled G suits have an advantage over the inflatable one,  in my opinion.

 

The p 51 pilot would have minor advantage at moderate G when the Gs are sustained. 

The current situation when the P51 has an advantage no matter what is not acuratel  and should be corrected.

 

Hi Kornezov,

interesting what you wrote, have you some data about how the valve works, or is it just speculating?

 

Are you sure G strain maeuvering was known at the time, and if it was as efficient as todays one?

 

I think that even the reclined seat at those speeds would not prevent the massive pooling of blood from the upper part of the body in the abdominal area. If no opposite pressure to pump the blood back towards the head, the reclined seat would work effectively only one time before letting pilots experience fatigue and reducing drastically their G resistance, no?

 

Just a question...

Edited by Caudron431Rafale

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There is some information how it works. I took the pressure data was from an e-book.
https://www.aerosociety.com/media/4847/a-brief-history-of-flying-clothing.pdf
Whenever more than 2 G are detected the valves open increasing pressure.

Regarding the G strain maneuvers. I think they were never called that in ww2. However there are multiple historical evidence of pilots sweating and being exausted by the muscle strain in high G combat. So what were doing all those guys during high Gs maneuvers? I think the G strain musclue contraction is as old as the fighter aviation. The new techniques are  different also including forceful pumping of 02 in the lungs. The operation of the pump requires also power that is also a limiting factor before the jet era.

What is also interesting  the centrifuges do not mimic oscilanting G, like those in instantanious turns. The air-inflated G suit is not made for that. The inclination of the seat is more important in the high G instantatious turn also the anticipation. That is why it is not as easy as people think to ride the backseat of f14 for example, if the pilots pulls some Gs without warning you you want to kill him afterwards.

Edited by JG27_Kornezov

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12 minutes ago, JG27_Kornezov said:

The inclination of the seat is more important in the high G instantatious turn...

 

So far, I've not seen any data giving actual figures for that, in regard to the sort of seating positions used in WW2 aircraft. In fact the only source I could find which discussed it at all seems to suggest that the effect of the seating position was small until the seat was tilted back a lot more than anything seen in WW2. And that raising the feet made little or no difference at all. The important factor seems to be the vertical distance between heart and brain.

 

 

https://forum.il2sturmovik.com/topic/57987-blackouts/?tab=comments#comment-886044

 

As for 'instantaneous' G, we've already seen data which shows that even without external assistance or specialised techniques, the human body can withstand significantly higher G for a second or so than it can for much longer. There is enough oxygen in your brain cells to support consciousness for such short durations, despite loss of blood pressure.  

 

If you are going to claim that a Bf-109 pilot with no G-suit has an advantage over a P-51 pilot with one under 'instantaneous G' conditions, you are going to have to find data to back it up directly.

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3 hours ago, AndyJWest said:

 

So far, I've not seen any data giving actual figures for that, in regard to the sort of seating positions used in WW2 aircraft. In fact the only source I could find which discussed it at all seems to suggest that the effect of the seating position was small until the seat was tilted back a lot more than anything seen in WW2. And that raising the feet made little or no difference at all. The important factor seems to be the vertical distance between heart and brain.

 

 

https://forum.il2sturmovik.com/topic/57987-blackouts/?tab=comments#comment-886044

 

As for 'instantaneous' G, we've already seen data which shows that even without external assistance or specialised techniques, the human body can withstand significantly higher G for a second or so than it can for much longer. There is enough oxygen in your brain cells to support consciousness for such short durations, despite loss of blood pressure.  

 

If you are going to claim that a Bf-109 pilot with no G-suit has an advantage over a P-51 pilot with one under 'instantaneous G' conditions, you are going to have to find data to back it up directly.

It is not a bad idea from time to time to read attentively the sources you provide, provided of course you have the ability to understand. It is clear from the article that one of the major problems is the efficiency of the inflation of the suit in modern G suits. Regarding high G instantaneous turns the p 51 virtual pilot  has an unfair advantage in the game. The instantaneous turn tolerance should be exactly the same for all pilots. Regarding sustained turns there is the advantage of the G suit. However only in the jet era planes were able to sustain enough high sustained Gs, p 51 is not f 15.
[edited]

Edited by SYN_Haashashin
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So, no data whatsoever to back up your claims that Bf 109 pilots without G suits have the advantage over P-51 pilots with them. What a surprise...

 

 

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54 minutes ago, AndyJWest said:

So, no data whatsoever to back up your claims that Bf 109 pilots without G suits have the advantage over P-51 pilots with them. What a surprise...

 

 

Heck, I still don't think we've seen anything to show just how much the seats are even tilted! And this is over several threads on the subject. People are getting this idea from some source somewhere but no one seems to be able to produce it. Surely there must be something out there to state this definitively.

The only thing I've seen that supports the seat tilt thing is a screen shot of a page from a comparative report done by the RAF between a Hurricane and a 109, where they stated that the 109 pilot appeared able to pull out of steep dives without blacking out, whereas it was more difficult to do that in the Hurricane. This was attributed to the more inclined 109 pilot position. But there were no more details listed. Much like all those reports that states that "X plane out-turns Y-plane" or "Y-plane out-dives X-plane", its frustratingly vague and difficult to assess for rigor or applicability. If the 109 has a G-force advantage, how much?

Once again - the only information I've seen that lays out the specifics regarding seat position deals with the F-16, which apparently grants 0.5-.75G. 

On 2/3/2020 at 5:52 PM, Panthera said:

In my personal opinion based on talking to lots of F-16 pilots their G-suit only adds about 1 G, so I'd be very sceptical of the idea that the very first G suits giving a 2-3 G advantage, esp. since not even the modern Libelle suits add that much. 

 

Infact I'd be very surprised if the WW2 G suit added even 1 G of extra max tolerance, and would be very interested in any data to back that up. The fact that modern G suits generally don't add more than 1 G of tolerance is quite telling IMO.

 

Thus IMHO this needs to be looked into, and I have no preference for any side.

As far as the 2G number, there's some indications that the early g-suits provided  2G of protection. This is an abstract in reference to a G-suit developed in Australia. Wikipedia says the Americans adopted the system. Unfortunately I can't get the full article.
https://pubmed.ncbi.nlm.nih.gov/2178602-the-development-of-the-australian-anti-g-suit/

It could be that the earlier G-suits provided more g protection but caused other issues that outweighed the value of the G-protection. Especially since, as in the source I posted above, a proper Anti-G Straining Maneuver appears to have a much greater effect on pilot resistance to G than a G suit, and therefore a suit that enabled a pilot to be more comfortable and exercise this maneuver properly may actually result in a higher net G-resistance. But this last bit is speculation.

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Part of the problem when trying to figure out how much protection a G-suit gives is that G-loc seems to be quite sensitive to rate of onset, in counter-intuitive ways. See the graph that Busdriver posted earlier:

Annotation 2020-01-19 02.jpg

 

I suspect that early centrifuge tests may have been done on equipment that took a relatively long time to spin up, missing the worst-case 6-8 second onset that hits the 'dip' between the high transient resistance (due to brain cells having enough internal oxygen for a few seconds) and the higher resistance that results from the heart being able to respond to high G better if the rate of increase is low. This could mean that rather than early G-suits being better than later ones, they instead weren't tested under the worst-case conditions.

 

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If tacview is right in showing Gs in Il-2 , what worries me how i can black out and lost conscious in 5 sec pulling only 2 Gs?

 

image.thumb.png.af8e0bc7ecd95c4214af59d1c0980c42.png

Edited by 1PL-Husar-1Esk

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That does seem strange. Do you get the same results in a WW2 aircraft?

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16 hours ago, AndyJWest said:

That does seem strange. Do you get the same results in a WW2 aircraft?

I need to test it , I did many test in Camel and 5 sec in horizontal spiral dive  maxing at about 2 Gs is enough to GLOCK . Those are tacview reading.

Anyway I need to do more test to eliminate 'sleeper' manoeuvres better. This can have significant impact in positive G threshold tolerance.

Edited by 1PL-Husar-1Esk

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I think I've figured out why there were odd results for G being reported by some people: it seems to be an issue with TacView .acmi files having incorrect data when recorded on the Arras map. Test a WW1 aircraft on anther map, and TacView seems to get it right.

 

I've filed a bug report:

https://forum.il2sturmovik.com/topic/58727-tacview-data-wrong-for-arras-map/

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On 2/10/2020 at 7:57 AM, Caudron431Rafale said:

Found this and already posted it in a similar thread. Seems like those G suits were very efficient:

 

This video is a akin to an after school special. The is pentagon's way of trying to convince pilots to wear the suit because it was extremely uncomfortable and they are very expensive.

When we in country in the early nineties you should see the full court press we were given on keeping our gas masks and flak jackets at the ready.

Edited by JG7_X-Man

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I'm getting the feeling some people are beginning to lean abit too much toward what they'd like as opposed to what is realistic.

 

I find it incredibly hard to believe the notion that G-suits somehow are worse today than 75 years ago, if anything they would get better. And as modern testing has shown even todays air inflatable G-suits only provide about 1 G of extra tolerance. It's only the newer liquid bladder Li Belle suits which are able to provide more, and that mostly because they react instantly. 

 

In other words I think even 1 extra G of tolerance for the WW1 G suits is being generous.

 

 

 

 

 

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