Forum: Military Aircraft of the Cold War

Forum Veteran Joined: Dec 15, 2006 - 12:28 AM Posts: 760

Hi,

I was hoping you could enlighten me on any other documentation of this F-15 mishap:

The next short clip shows the cockpit/HUD view From an F-15 that the pilot became spatially disoriented. If I remember correctly it was broad daylight in clear visibility, a mitigating factor is the color of the sky and seas that day were very similar.

F-15 Eagle Spatial Disorientation: World Record G: http://www.youtube.com/watch?v=_-adcRA3u8Q

The fact the F-15 held together and was able to land safely is a testament of its durability. I can't remember exactly but it sustained like 15-20 Gs for about 2-3 seconds. For a fraction of a second it pulled something like 30-40 Gs. It held together but the wing skin had crinkled (technical term j/k) because the airframe was bent so badly. Unfortunately I have no external views. It pulled so many Gs that the tape pulled off the recorder head and lost sync for a bit, so the tape misses the highest G.

As far as I know it was the most Gs a piloted aircraft ever pulled and was able to return safely (though the plane was badly damaged).

I would like to know if anyone has any photos or video of the F-15 after it’s mishap, documenting the damage.

Thanks

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yes this would be very interesting

Well I'll take the G quotes as a given but wheredaheck was the G-meter in the HUD? Too jumpy to clearly make it out.

Forum Veteran Joined: Dec 15, 2006 - 12:28 AM Posts: 760

The video was damage by the high G. I think the data recorder was OK, but I don’t have the data. I never was told the exact number of Gs it pulled. Either the people telling me didn’t know or they didn’t think they could. I didn’t want to ask too many questions, If you know what I mean.

They gave me the wide range of vague figures I posted to the best of my recollection. They insisted it was genuine, and to their knowledge it was the highest G a manned aircraft ever returned safely. It was the same sources that let me copy some of this great footage 1-2 decades ago.

ATFS_Crash wrote:

The fact the F-15 held together and was able to land safely is a testament of its durability. I can't remember exactly but it sustained like 15-20 Gs for about 2-3 seconds. For a fraction of a second it pulled something like 30-40 Gs.

The pilot withstood 40Gs?!?! Shocked

Correct me if I'm wrong, but isn't one of the reasons why jets are limited to 9g is because the human body can't function properly beyond that point?

Forum Veteran Joined: Dec 15, 2006 - 12:28 AM Posts: 760

I do not blame you for being skeptical. It is good to be a little skeptical. Goatmilk you are right and wrong; it is more complex then you are making it out to be.

There is a difference between sustaining Gs or short duration or fraction of a second. I am not sure what the peak value was. I was hoping someone could know of or find more documentation on this incident to clarify.

It takes a good pilot to sustain 9 G or more. There is a big difference between sustaining Gs and extreme short duration.

A sudden onset of Gs can be dangerous if it is sustained because a pilot might not have time adapt to the changes, particularly if it is unexpected. But in an extreme duration G incident.

It takes a few seconds for the blood to drain from the brain and for the brain to become hypoxic. Once you become hypoxic it can take a few seconds to recover after the G. is reduced to normal, it takes all while for the blood to return to the brain and for the oxygen to reach the brain cells. If you were to suddenly pull 20 Gs you would certainly pass out, but it would likely take from 1-20 seconds. It depends on a lot of factors, training, body condition, body type, severity, duration, position, ect… Part of the reason some planes have a semi reclining seat is to give the pilot more resistance to Gs. In WWII the Germans had or were working on an attack aircraft that the pilot was in the prone position, I do not know what the Germans intent was, but this would have given the pilot an incredible resistance to Gs.

You here of Murphy's Law?
http://www.edwards.af.mil/history/docs_ ... s_law.html
Pulling 40 Gs

http://www.edwards.af.mil/history/docs_ ... raphy.html
By riding the decelerator sled himself, Dr. Stapp demonstrated that a human can withstand at least 45 G's in the forward position, with adequate harness.[/url]

I saw a video of a guy a few days ago of a guy pulling 8 Gs holding Nuts magazine strait out in front of him (arms strait) as a challenge and a prank. He estimated the magazine weighed the equivalent of a phone book. It is hard telling how much the weight of his arms added. It likely took 100 to 200 pounds of force to hold the magazine like that. Unfortunately he deleted the video, I thought it was pretty funny and a great demonstration.

I doubt people could survive much more than 50 Gs (instantaneous/short duration) in the upright position. I doubt a person could survive much more than 100 Gs (instantaneous/short duration) in the horizontal.

When I say lying down, that is not quite technically correct either, it is an oversimplification. It is normally correct to say lying down, but to be more correct in a position that puts less stress on your body and that tends to be in a position with more surface area in contact with the resisting object, is a position that you are less likely to have major organ damage and fractures in a high G. incident. Lying down in a Wright Flyer flying horizontally into a brick wall would be lousy. Lying down as your body is the ground in a skydiving accident would be more appropriate. Like Einstein said it is all relative.

http://greenharbor.com/fffolder/ffresearch.html Think about all the sky divers that have had their parachutes fail, yet survive.[/url] I think in most cases terminal velocity is around 90 miles an hour with the streamer (a badly collapsed canopy). I think there has been at least one case a pilot or crewmember bailed out at high altitude with no parachute at all, yet he survived. I think terminal velocity without a parachute is around 120 -150 miles an hour.

It would be difficult for person to hold up their head, especially with a helmet on. That is why the US military has been slow to adopt a helmet mounted eye reader. The U.S. military has even toyed with brainwave sensors to detect when a pilot loses consciousness (to automatically turn on the autopilot), there is even early testing with mind control. To have such heavy headgear can be very fatiguing, especially when pulling heavy Gs. The weight of the standard helmet can be fatal in an accident, let alone ones with more advanced features. In most cases the protection that a helmet gives for impact, far outweighs the risk of neck fracture.

Unlike the guy holding the Nuts magazine is using mostly his muscles. A pilot in proper posture most of the weight from the head should be on the spine, not muscle. So a pilot with good discipline can hold up their head even under extreme Gs, the downside is when gravity becomes excessive; it can collapse your spine, instead of your muscles just failing.

It is like the people but instinctively brace themselves for a crash, in a minor crash they can prevent minor injuries, but in a major crash there is actually more damage because the instinctive bracing is for a person to have their arms and legs braced and locked. If you know you are going to crash, you should keep your legs and your arms slightly bent. If you instinctively brace for a crash you are more likely to have broken legs, arms, back, ECT… If you brace yourself instinctively you more likely to break bones, if you use proper brace positions your muscles will absorb a lot of the energy.

There is a lot of basic science in learning how to survive in combat and in a crash. Even if you are in a car it is important to wear a seatbelt. Wearing a seatbelt is to your advantage for many reasons, the most obvious is that it keeps you in the vehicle; the second is the seat belts are usually softer than having your face smashed into the windshield and having the steering column shoved through your heart. The deeper physics of why seatbelts are so effective is that if you are fastened to the vehicle then you deceleration with the vehicle, which is more slowly, because of crumple zones, it takes time to crumple thusly reducing the G. loading. If you do not wear seat belts you can continue moving until after the vehicle stops so when you do stop, it is much more sudden, thusly the G. forces are much higher, thusly you absorb the energy, not your car. Another advantage to seatbelts is if you hit rough road or if you are in aircraft and hit turbulence, the seatbelt keeps you seated at the controls so you can maintain or regain control of the vehicle quicker.

Medicine, piloting, safety are all sciences, but they are not always exact there is a little bit of art and luck involved. When luck is involved, use your mind and science to try to shift the luck/odds more into your favor.

So was that a lecture on G or a push for seatbelts? Kidding. Good read Smile

I thought 11G's was the most the human body could withstand................. Shrug

goatmilk wrote:

Correct me if I'm wrong, but isn't one of the reasons why jets are limited to 9g is because the human body can't function properly beyond that point?

The Eagle does not have a G limiter. It can pull past 9. However, IIRC anything over 9 requires an inspection, which from what I've been told is a PITA.

The Viper does have a G limiter, which is supposed to hold at 9, but short pulls over 9 can and have been done.

I for one am skeptical as to the max number of Gs, but I don't doubt for a second that the Eagle Driver was able to pull well past 9 Gs. I've mentioned Jon Counsell's supersonic bailout several times on this site. Having spoken to him, and the crew chief of the bird, it was determined that he had pulled somewhere in the range of 17 Gs, trying to avoid a collision with his IP in an ACM mission. He G-LOCed, and came to in time to realize that he was supersonic and couldn't pull out before going into the Gulf. He had no choice but to punch out supersonic.

There was also a fatal mishap involving an Eagle from Elmendorf, which had just taken off from Galena. He made a near supersonic pass over the field with a full armament and fuel load, including 3 drop tanks. He tried to pull into a max climb, and ripped the wings off of the jet. The jet disintigrated and went down in the Yukon River. Not sure on the number of Gs pulled, but the added weight of the drop tanks and missiles increased the structural load on the wings, leading to their destruction.

Stapp proved the maximum number of instantanious Gs which a human can tolerate. I don't know what the max number of sustained Gs a human has ever attained.

Go to Wikipedia and check out "acceleration due to gravity". Its got some good stuff. The record is apparently a racecar driver who hit a wall and survied. Pulled something like 175g's. I wish there was an external picture of this Eagle.

Once again, though, that is an instantanious onset and offset of Gs. Nothing could survive that many sustained Gs. For an over-G that the pilot was able to bring back, this Eagle would likely have the record. For what it's worth, it would be a very dubious record to hold. The first thing that would happen, is the pilot would get in some deep Sierra, and the second thing, is you've busted a plane which probably can't be fixed.

TC wrote:

The Eagle does not have a G limiter. It can pull past 9.

It should also be noted that it isn't as easy getting 9Gs from an Eagle than it would be in comparison to a Viper. In an Eagle, you need a lot of finesse and muscle memory to max perform it.

TC wrote:

I for one am skeptical as to the max number of Gs, but I don't doubt for a second that the Eagle Driver was able to pull well past 9 Gs. I've mentioned Jon Counsell's supersonic bailout several times on this site. Having spoken to him, and the crew chief of the bird, it was determined that he had pulled somewhere in the range of 17 Gs, trying to avoid a collision with his IP in an ACM mission. He G-LOCed, and came to in time to realize that he was supersonic and couldn't pull out before going into the Gulf. He had no choice but to punch out supersonic.

There was also a fatal mishap involving an Eagle from Elmendorf, which had just taken off from Galena. He made a near supersonic pass over the field with a full armament and fuel load, including 3 drop tanks. He tried to pull into a max climb, and ripped the wings off of the jet. The jet disintigrated and went down in the Yukon River. Not sure on the number of Gs pulled, but the added weight of the drop tanks and missiles increased the structural load on the wings, leading to their destruction.

Stapp proved the maximum number of instantanious Gs which a human can tolerate. I don't know what the max number of sustained Gs a human has ever attained.

Good and interesting info on these incidents.

we cracked two seperate wing assemblies in PSAB during the war because of full combat load max climbs. Made for some intersting EOR checks with fuel streaming out all over live weapons and dangling pylons.

akruse21 wrote:

we cracked two seperate wing assemblies in PSAB during the war because of full combat load max climbs. Made for some intersting EOR checks with fuel streaming out all over live weapons and dangling pylons.

Did you axe the flights or let them go?

we performed the first and second in field wing swaps along with depot help for the first time ever as far as i know and was told. They eased off the max climbs after that and after we returned from the desert we were restricted from flying with wing tanks for a while until they were beefed up at depot.

Forum: Military Aircraft of the Cold War

F-15 Eagle world record G