[pieterbreed]

There is a rumor going around in the South African Air Force that the South Africans with the help of the Israeli Air Force (who had big ties in the bad old days) figured out a way to shoot the SR71s down. It had to do with a technique called storm-climbing (which was novelized by Wilbur Smith in 'Eagle in the Sky') where a normal fighter aircraft would go full-tilt with maximum weight in a downward trajectory, flatten out the dive, dump excess weight, and start climbing vertically. This way the pilots would get to an altitude where the missiles could get a successful lock, which in this case was far higher than the 'normal' ceiling for these aircraft. From this height they could then fire off the missiles. I'm not at all sure if they ever attempted it, but I'm pretty sure they didn't succeed. Still in interesting thing to hear :)

[z303]

The biggest problem I see with intercepting a SR-71, is not getting another plane up to the same sort of altitude but getting the plane in the right piece of the sky, taking the wikipedia stats as an example, Mach 3.2 (2,200+ mph, 3,530+ km/h,1900 knots+) at 80,000 ft (24,000 m), if your interceptor take 2 minutes to get up to 80,000 ft, even doing some sort of zoom climb your aiming at a point 73 miles in front of the SR-71 position at take off, and I would expect the real world time to be longer from detection to interceptor at altitude. So you could only do it with a large radar network to track the SR-71 plus airbase in front of the current flightpath.

Then even if you did launch a missile it would not have an easy job of hitting the target

[z303]

The SR-71 used something similar to go supersonic,

'After take off and the top up the Blackbird will perform a manoeuvre called the Dipsy Doodle, here it passes mach 1 by a climb to 33,000ft followed by a sharp dive to allow the aircraft to traverse high drag transonic range without using a lot of fuel. The aircraft will then climb to at least 60,000 ft.'

http://www.historyofwar.org/articles/weapons_blackbird.html

[Rod]

That storm-climbing maneuver sounds really cool!!! Do you have more detailed info on that? Other than Wilbur Smith's novel, that is.

It reminds me of that classical optimal control problem in the 1960s: the U.S. Air Force wanted to find the fastest climb for its F-4 Phantoms (so they could reach their operational ceiling ASAP to intercept Soviet bombers). The optimal path was counter-intuitive: first climb, then dive, reach supersonic, climb again. Sounds crazy, but they could reduce the climbing time dramatically that way!

[nuclear_eclipse]

I've actually noticed that behavior myself when screwing around in X-Plane with the F-4E; I take off at low-speed, high AOA to gain a few thousand feet, and then drop the nose at full afterburner to use both the engines and gravity to go transsonic, at which point the F-4 can accelerate faster, and maintain a higher angle of climb without losing velocity, due to the "lower" drag at supersonic speeds.

I had figured it was perhaps a weird characteristic of the simulation's breakdown of airframe components, but if that's how things worked in the real F-4's, that just gives me that much more respect for the physics simulation in X-Plane. No wonder it's FAA certified :)

[Rod]

The seminal paper in which these findings were published:

BRYSON, A.E. and DENHAM, W.F., "A steepest-ascent method for solving optimum programming problems," Trans. ASME. J. Appl. Mechanics, June 1962, pp. 247-257.

I can't find a PDF copy anywhere. It sucks. If you want to read a non-technical paper on it, try this one: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=00506395

[pieterbreed]

Well, I don't have any material on it but you can see that it makes sense from a mechanical physics point of view. Load up a craft to maximum possible weight (with ballast even) Then fly as high and is fast as you can (during which you build up the maximum achievable potential and kinetic energy) then during a dive build up as much speed as you can (during which you convert your potential energy from the weight and height of the craft into more kinetic energy) as you level out, you dump the excess weight and start climbing. Since you now have less weight but the same kinetic energy, you are free to take your craft higher than the height from which it started to descend.

[Rod]

Yes, your explanation makes sense. That's what I thought. Nonetheless, I was interested in more in-depth technical info... some technical papers / reports on it would be interesting. By the way, have you heard of the pop-up maneuver?

[pieterbreed]

no! please elaborate! :)

[Rod]

The pop-up maneuver's goal is to minimize exposure to enemy fire. Imagine that you're flying an F-16 over enemy territory and that you want to hit a nuclear power-plant with a couple of JDAM's. Since the target is certainly protected by lots of AAA and SAM's, you want to drop the bombs as far away as possible from the target. In other words, you definitely do not want to fly over the target, as that will most likely get you shot down.

You can use the pop-up maneuver then. You fly low and fast to avoid radar detection and AAA fire. When you get close to the target you climb at 45 degrees, roll 180 degrees (you are now flying inverted), prepare the JDAM's to be deployed. You then pitch up and when you are at the top of a parabolic flight path, you release the JDAM's. The inertia build-up during the ascent will make the bombs go faster and farther. Once the bombs are deployed, you fly low again.

There are some technical papers on this. It's heavy math: optimizing flight paths is not exactly a trivial problem ;-)

[pieterbreed]

This sounds very much like something the SA Air Force did with their mirages in the Bush war of the 70's and 80's.

BTW - There is a book written about the history of the Mirage in the SAAF called 'vlamgat' (lit. fire/fiery - behind/ass). Try http://www.saairforce.co.za/reviews/33/vlamgat-cd.

Anyway. In this book, which is written by an ex-pilot, a maneuver is described which sounds very similar to the pop-up. The aircraft also approaches the target at low altitude, then pitches up. As the pilots pull up on the stick they release their bombs, but continue climbing up and away. The bombs (old fashioned, dumb bombs) would then fly in a parabolic trajectory like you'd expect and land somewhere near the target ;)

If I remember correctly this tactic was actually used in combat with surprisingly effective results. I say surprising because nobody believed you could actually hit a target with a bomb that flies in a trajectory with a horizontal length of a few 100 to 1000 meters and was released on the pilot's 'gut' feeling...