A photoshoot at the edge of space

[Flyboy]

https://www.thedrive.com/the-war-zo...y7D8jbt94q6bYimcQSNZoGo3Y5eQUNp_IfJNPocD2NOso

I never expected to ever see the Dragon Lady in an air-to-air photoshoot at her operational altitude, but here we are. Apparently this was in the works for 6+ years to make happen, but by god was it worth it.

“Doing a photoshoot like this at the edge of space is entirely different than when I did the same thing with fighter jets,” Blair reflected. “At these altitudes, there are only 5 knots of speed that separate the planes from going so fast they fall apart or going too slow that they fall out of the sky completely. For this reason, we had to use geometric turns to stagger the aircraft rather than having the second plane speed up or slow down, which was yet another complexity that made this photoshoot as challenging as it was.”

Give the whole article a read. It's really neat.

 

[BillTre]

The article has some real nice pictures.
They kind of have a feel, aviator-noir.

I hope they got that guy out of the engine.

 

[Baluncore]

Nice.
Q. "Where is the U2 flying today"?
A. "The same place as usual; coffin corner".

 

[berkeman]

Great stuff, thanks @Flyboy

BTW, what are "geometric turns"?

“At these altitudes, there are only 5 knots of speed that separate the planes from going so fast they fall apart or going too slow that they fall out of the sky completely. For this reason, we had to use geometric turns to stagger the aircraft rather than having the second plane speed up or slow down, which was yet another complexity that made this photoshoot as challenging as it was.”

 

[phinds]

The Flat Earth Society is going to have some choice words for those faked pics that show the edge of the Earth as curved.

 

[jrmichler]

The Flat Earth Society is going to have some choice words for those faked pics that show the edge of the Earth as curved.

The Flat Earth Society is going to use those obviously unfaked legitimate pics to prove that the Earth is a flat, round disk.

 

[Flyboy]

I hope they got that guy out of the engine.

Hey, it's better than the guy who has to inspect the inlet duct on an F-16. Damn thing has a strut in the middle of it you have to be mindful of on your way back out.

BTW, what are "geometric turns"?

Not entirely sure, but from my understanding and (admittedly virtual) experience in formation work, they're talking about using different turn rates/radii to adjust their spacing. I.E. if one plane turns "inside" the other while maintaining the same airspeed, the inside plane will seem to move faster than the one on the outside. The inverse is actually something you have to keep in mind during more typical formation flying. Guy on the inside of the turn has to throttle back a touch, guy on the outside has to throttle up a touch. Flight lead gets to sit there fat dumb and happy and critique the other guys for poor stationkeeping.

 

[BillTre]

BTW, what are "geometric turns"?

Hey, it's better than the guy who has to inspect the inlet duct on an F-16. Damn thing has a strut in the middle of it you have to be mindful of on your way back out.

Not entirely sure, but from my understanding and (admittedly virtual) experience in formation work, they're talking about using different turn rates/radii to adjust their spacing. I.E. if one plane turns "inside" the other while maintaining the same airspeed, the inside plane will seem to move faster than the one on the outside. The inverse is actually something you have to keep in mind during more typical formation flying. Guy on the inside of the turn has to throttle back a touch, guy on the outside has to throttle up a touch. Flight lead gets to sit there fat dumb and happy and critique the other guys for poor stationkeeping.

I think they mean something like this:

 

[berkeman]

I think they mean something like this:

Um, no.

 

[BillTre]

Um, no.

If the planes have to largely maintain an airspeed, then they can adjust their relative positions by turning in arc of different radii.
Like what Calvin was contemplating.

 

[Flyboy]

If the planes havev to largely maintain an airspeed, then they can adjust their relative positions by turning in arc of different radii.
Like what Calvin was contemplating.

Correct.

Here, lemme throw up another formation shot, this time from DCS.

The Mirage in the back is on the inside of the two Viggens. Flight lead is on the outside (in 11), at the front of the stack. All aircraft are currently in a right bank. Normally, for the Mirage to maintain formation in the correct spot with the lead plane, he'd throttle back because he's got a smaller turn radius and covers less distance. If it were reversed and turning left, he'd have to throttle up to stay in position to cover the longer arc. It's a bit challenging to wrap your head around at first, but it get easier with practice.

The U-2s didn't have that luxury of airspeed adjustment. They have a very narrow flight envelope at that altitude, typically listed at ~+/- 5 knots indicated airspeed. Adjusting your airspeed to adjust your position is not an option. You have to play with your relative velocities to make it work. So, to close on the other plane, they would need to turn tighter than the plane they're trying to chase. Likewise, if they need to back off, they'd turn outside of the lead plane. There's no doubt a lot of radio chatter going on to coordinate that kind of work, as there's only so much you can brief on the ground.

If there's still confusion, I can try to get a session with another pilot in DCS to get some examples. The Viggens would provide an excellent platform for that, as they've got an autothrottle that allows them to hold a fixed airspeed and we can use that to emulate the limited flight envelope.

 

[Haborix]

The various turns must alternate between the two planes so that over the entire flight the distance between them doesn't grow. I imagine it like having two strings of equal length (the flight paths) with their end points pinned to together (the planes must start and end the flight together). You can deform the two strings however you like to represent a flight path (without stretching the strings or moving their end points). Two points moving along the deformed strings at equal speed, starting at one of the end points, will have a displacement vector (the line of sight for the photo) determined by how the strings were deformed.

P.S.: This would be a great real world example to serve as a starting point for some fun problems in an introductory differential geometry course.