# F22

#### Chris Calohan

##### Well-known member

9G Inverted Dive: Chris Calohan​

#### Asher Kelman

##### OPF Owner/Editor-in-Chief

9G Inverted Dive: Chris Calohan​

Fabulous!

How many folk can withstand such forces?

Asher

#### Doug Kerr

##### Well-known member
Hi, Chris,

9G Inverted Dive: Chris Calohan​
Fabulous shot of a fabulous machine.

For several years we had a squadron of F-22s at Holloman Air Force Base here in Alamogordo, but the squadron is now based elsewhere.

Does "9G dive" mean that the pilot experiences a gravitational force of 9G when pulling out of the dive? I can't believe that the gravitational force during the dive itself is that great.

Thanks again for the great shot.

Best regards,

Doug

#### Asher Kelman

##### OPF Owner/Editor-in-Chief
.......

Does "9G dive" mean that the pilot experiences a gravitational force of 9G when pulling out of the dive? I can't believe that the gravitational force during the dive itself is that great.

Doug,

One would think that "9 G" of weight sensation would be derived from "1G", (gravity) plus 8 G downwards vertical engine thrust. However, in free fall, no "weight" sensation is felt by the body, so that "9G" is all engine thrust! I know selected pilots can be trained to withstand 8 G.

Asher

#### Doug Kerr

##### Well-known member
Hi, Asher,

Doug,

However, in free fall, no "weight" sensation is felt by the body, so that "9G" is all engine thrust!

For the pilot to feel "9G" of force against his seat back during the dive, the acceleration of the aircraft would have to be 10 times that of free fall. I find it hard to believe that an aircraft in a powered vertical dive would have that degree of acceleration.

For example, if its speed at the top of the dive were 500 mi/hr, then after a five second vertical dive at 10G vertical acceleration its speed wouild be about 1590 mi/hr.

After a 2-second vertical dive at 10G acceleration, with an initial speed of 500 mi/hr, its speed would be about 936 mi/hr.

I have to think that the "9G" value pertains to the radial acceleration (typically resulting in a force on the pilot down into his seat) during pull-out.

I know selected pilots can be trained to withstand 8 G.

Yes, that is quite amazing. And evidently at least one 9G (unless that F-22 was unmanned).

Best regards,

Doug

#### Doug Kerr

##### Well-known member
It seems that the thrust of an F-22 is at best about 1.25 times its weight.

That means that in a vertical dive at full thrust, its acceleration would be about 2.25G.

The pilot would feel a force against the seat back of about 1.25 times his weight.

Best regards,

Doug

#### Don Ferguson Jr.

##### Well-known member
They wear G-suits too unlike the Blue Angels who have to learn ways for tensing muscles to control from blacking out.
It has to do with where the control stick is located inside the Hornet. Thunderbird pilots wear G-suits.
Don

#### Chris Calohan

##### Well-known member
I know I heard some pilots talking about some of the turns they made where they got close to 8 G's and said when they come out of that dive and push the stick back up, they nearly hit 9 but pilots are like fishermen...I just used that number to emphasize the thrust of the aircraft as he was not in free fall but had the pedal to the metal, so to speak...

When he came out of that dive, he was humming right along...

High Speed Pass: Chris Calohan​

#### Antonio Correia

##### Well-known member
Stunning images of a great plane which is, indeed, very beautiful with a superb design and exceptional qualities

I was amazed - I knew it already - to read how much money is spent in a machine like this and all money it in mechanics, personnel and so forth...

Strange - it always has always been this way - how Human Kind spends so much effort in economics related to ... war, to kill, to supremacy ! So many people starving in the World ...

I read that the US just sold 17 F35 (even better than F22, the most expensive weapon in history BTW !) to Israel and agreed - September 2016 - to provide Israel a record \$38 billion in new military aid over the next decade !

Crazy World ! Let's move on.

Great images indeed !

#### Asher Kelman

##### OPF Owner/Editor-in-Chief
Stunning images of a great plane which is, indeed, very beautiful with a superb design and exceptional qualities

I was amazed - I knew it already - to read how much money is spent in a machine like this and all money it in mechanics, personnel and so forth...

Strange - it always has always been this way - how Human Kind spends so much effort in economics related to ... war, to kill, to supremacy ! So many people starving in the World ...

I read that the US just sold 17 F35 (even better than F22, the most expensive weapon in history BTW !) to Israel and agreed - September 2016 - to provide Israel a record \$38 billion in new military aid over the next decade !

Crazy World ! Let's move on.

Great images indeed !

Yes indeed. A wonderful plane!

Asher

#### Doug Kerr

##### Well-known member
Hi, Asher,

I said:

For the pilot to feel "9G" of force against his seat back during the dive, the acceleration of the aircraft would have to be 10 times that of free fall.

That is true, as far as it goes. However, since the aircraft, left to its own devices (in "free fall", like the pilot) would accelerate with an acceleration of "1G", then for it to accelerate with an acceleration of 10G would require a thrust with an acceleration effect of 9G, which I think is what you had conjectured. I was in error to suggest otherwise.

However, again, for this kind of aircraft, the maximum available thrust is estimated to have an acceleration effect of perhaps 1.25G.

And of course we have since learned that the "9G" figure cited was, perhaps, "fanciful".

Best regards,

Doug

#### Asher Kelman

##### OPF Owner/Editor-in-Chief
Doug,

The max G forces possible are in the region 8.5, but the free fall G is not felt. What is felt is an increase in body weight when we go over 1.0 G. We can sense, by the way, the second derivative of that change very well, especially when the lips are distorted and turn inside out, LOL!

Asher

#### Don Ferguson Jr.

##### Well-known member
Chris, cool shots of the F-22. I would like to see the first one in color.
Don