High altitude & low G-force

[Windjammer]

Ever wondered why aircraft don't always operate out of harms way and have to release or fire weapons from a certain altitude. High altitude means low g-force, hence the effect on carrying out such exercise.

https://www.facebook.com/video.php?v=466591793511320

 

[Windjammer]

Didn't want to start another thread hence posting it here.
Found this video of an awesome demo by an F-16 in a 2009 airshow.
What caught my eye was the manoeuvre it executed @ -3.15.... @gambit @Oscar @Tipu7 @Horus , @HRK...check it out guys.

https://www.facebook.com/video.php?v=998478130269999

 

[HRK]

Didn't want to start another thread hence posting it here.
Found this video of an awesome demo by an F-16 in a 2009 airshow.
What caught my eye was the manoeuvre it executed @ -3.15.... @gambit @Oscar @Tipu7 @Horus , @HRK...check it out guys.

https://www.facebook.com/video.php?v=998478130269999

that was really some strange maneuver which it performed .... I would really like to read the comment of @gambit about this ....

 

[SQ8]

Didn't want to start another thread hence posting it here.
Found this video of an awesome demo by an F-16 in a 2009 airshow.
What caught my eye was the manoeuvre it executed @ -3.15.... @gambit @Oscar @Tipu7 @Horus , @HRK...check it out guys.

https://www.facebook.com/video.php?v=998478130269999

High performance turn.

 

[Tipu7]

Didn't want to start another thread hence posting it here.
Found this video of an awesome demo by an F-16 in a 2009 airshow.
What caught my eye was the manoeuvre it executed @ -3.15.... @gambit @Oscar @Tipu7 @Horus , @HRK...check it out guys.

https://www.facebook.com/video.php?v=998478130269999

Apparently F16 was on vodka ......
Never seen this thing before

 

[Windjammer]

High performance turn.

While the American pilot performs the manoeuvre after disengaging the afterburner, with air brakes open and in a climb, our boy does something similar but with burner engaged and in a dive @ 2.08.

 

[gambit]

that was really some strange maneuver which it performed .... I would really like to read the comment of @gambit about this ....

Nothing strange. He is just having a great time. The F-16's quickness in entering maneuvers sometimes give the impression that the jet is doing something 'funny', but look at the OODA loop...

- Observation
- Orientation
- Decision
- Action

The F-16's was design for no. 2. The quicker you can orient yourself, thanks to a great combination of airframe and engine, the better the odds of positioning yourself advantageously and/or quicker exit of an inferior position.

People might not believe this, but flying fast is not 1/10th as fun as flying maneuvers. Every pilot want to fly a clean jet so he can maneuver and nothing in the modern inventory is soooooooooo damn seductive to go nutso like a clean F-16. The man was having public carnal knowledge with his jet.

 

[krash]

Ever wondered why aircraft don't always operate out of harms way and have to release or fire weapons from a certain altitude. High altitude means low g-force, hence the effect on carrying out such exercise.

https://www.facebook.com/video.php?v=466591793511320

Correct me if I'm wrong but the difference in G at low and high altitudes (attainable by aircraft) is negligible. For example, the SR-71's (one of the highest flying aircraft ever) highest attainable altitude was 25,929m or 25.929Km. The average distance at the equator from the Earth's centre of gravity is 6400Km with an average G of 9.8m/sec^2.

So the SR-71 flying at 25,929m would experience,

g1/g2 = (r1/r2)^2

9.8/g2 = (6425.929/6400)^2

g2 = 9.7210724123056078770968667923652 m/sec^2 acceleration due to gravity.

which when rounded off is 0.9919462G (a difference of 0.80538% only). You can actually get this variation in G on the surface of the Earth as well.


Higher altitudes in flight are more desired due to the difference in atmospheric density. The video, I believe, is on the effects of low 'relative gs'. These would, of course, differ in multiples of 0.80538% of x when at 25,929m (x being the relative g experienced by the aircraft at the time) but it still would be negligible, e.g. a turn which induces 9gs near the surface of the Earth would still induce 8.9275158gs at 25,929m. Plus none of the aircraft seem to be making sharp changes in their vector.

 

[Windjammer]

Correct me if I'm wrong but the difference in G at low and high altitudes (attainable by aircraft) is negligible. For example, the SR-71's (one of the highest flying aircraft ever) highest attainable altitude was 25,929m or 25.929Km. The average distance at the equator from the Earth's centre of gravity is 6400Km with an average G of 9.8m/sec^2.

So the SR-71 flying at 25,929m would experience,

g1/g2 = (r1/r2)^2

9.8/g2 = (6425.929/6400)^2

g2 = 9.7210724123056078770968667923652 m/sec^2 acceleration due to gravity.

which when rounded off is 0.9919462G (a difference of 0.80538% only). You can actually get this variation in G on the surface of the Earth as well.


Higher altitudes in flight are more desired due to the difference in atmospheric density. The video, I believe, is on the effects of low 'relative gs'. These would, of course, differ in multiples of 0.80538% of x when at 25,929m (x being the relative g experienced by the aircraft at the time) but it still would be negligible, e.g. a turn which induces 9gs near the surface of the Earth would still induce 8.9275158gs at 25,929m. Plus none of the aircraft seem to be making sharp changes in their vector.

I think you are missing the main point here, we are talking about weapon release, due to very low gravity, the ordnance instead of falling down either simply floats in the air or gets caught in the slipstream.

 

[krash]

I think you are missing the main point here, we are talking about weapon release, due to very low gravity, the ordnance instead of falling down either simply floats in the air or gets caught in the slipstream.

That's what I'm contending; the gravity can't be very low at all, it should be pretty much the same as what you get on the surface of the Earth. So, IMO, the phenomenon shown in the video is a result of some other factor.

 

[JamD]

I think you are missing the main point here, we are talking about weapon release, due to very low gravity, the ordnance instead of falling down either simply floats in the air or gets caught in the slipstream.

I think you may be confused. Even at orbital altitudes the gravitational acceleration due to Earth's gravity is pretty significant. Even at 500 km altitude (that's 1,640,400 ft) it is a little less than 8.5 m/s^2, nothing that will cause anything to float. I think you are confusing acceleration due to gravity with the load factor, colloquially called "g", that an aircraft pulls in a maneuver.

At high altitudes due to the decrease in air density an aircraft needs to fly faster to generate the same amount of lift. Assume at sea level the aircraft makes a level turn of some radius R and pulls 7 g's (load factor). Now assume at some altitude where it needs to fly 1.2 times as fast to generate the same lift. At this increased speed say you want to make the level turn of radius R again, you will need to pull 13.5 g's. Since you can't possibly sustain that (or fly slower or you'll stall), it is generally said you can pull lower g's at higher altitudes. That is the "low g's at high altitude".

What the videos in the original post show are aerodynamic effects.
EDIT: Perhaps what the video is trying to portray is the effect of weapon release at g or load factor equal to 1 or smaller (ie in level flight or turning the nose down). This explains why ordinance are never dropped while pulling down but always level or pulling up. It has little to do with altitude.
Here is some counter evidence to the claim that ordinance cannot be launched from high altidude:

@krash is very right here.

 

[moon_light]

How can you see such blurry number ??