#but the spin technique could also be compared to a blizzard too i realized !

[fapangel]

So that Tu-22 crash. I'm having trouble figuring out how the fuselage snapped right the fuck in half. It was definitely a hard landing, but you'd think a combat aircraft could handle that. Was the descent faster than the video suggests or something, or was it just a worn-out airframe?

For those who missed it, the video in question.

Truth be told, I doubt it was the airframe’s fault. Aircraft can be significantly more fragile than most people realize. It is entirely possible in a great many civilian aircraft to over-stress the airframe with control inputs. On fly-by-wire aircraft the computer will usually stop you from going too far, but on smaller private aircraft, the incautious pilot can easily warp the airframe if they yank on the stick too much. Pulling 2 gravities in a turn is effectively doubling the load of the aircraft, for instance. It’s not impossible to rip the wings off, but usually the engine will part company first. Formal airframe g-limits are actually determined by the strength of the engine mounts (as they’re much smaller than the wing roots, but supporting the densest weight in the whole aircraft.) Obviously, aircraft load effects this quite a bit. After installing the Huge Wonderful Mod Pack everyone uses for IL-2 1946, I took a fully-loaded B-25 out for a spin, yanked on the stick like I usually do, and watched in dismay as the wings promptly parted company with the fuselage full of heavy bombs. D:

Military aircraft are built for performance with the most advanced, expensive materiel available, but they still have to contend with the same engineering trade-offs. For instance, early-war American fighters like the P-40 and F4F Wildcat were legendarily strong; the P-40 had five main wing spars (most aircraft have two,) which made it so tough that one Soviet pilot rammed and destroyed two German fighters with his wingtip - and the wingtip wasn’t even severely damaged. (Most of the time a mid-air collision guarantees destruction of both aircraft.) But all that structural reinforcement came at a steep cost in weight, which is why lighter Japanese and German fighters could easily fly loops around the P-40. On aircraft, weight is the enemy, and the lighter you can make the airframe, the faster and further you can go, with more payload.

Where a plane is strong varies greatly, as well. Wings are usually very strong, as they’re literally carrying the weight of the entire aircraft, and they also have to flex a bit in flight, especially on big airliners. The fuselage usually isn’t subject to nearly as much stress. The size and mission of an aircraft also determine requirements. Fighters can expect to be shot at and have to perform very heavy-G maneuvers, so they’re built as compact and strong as possible. Bombers need range, speed and payload above all with maneuvering an afterthought, so they save their structural reinforcement for the wing roots (to lift all that weight) and redundant systems in the fuselage to make them resilient against battle damage. As long as the wings stay attached to the fuselage, and the fuselage has at least one of all the important things (hydraulic control systems, fuel tank, and engine,) they can typically come home, even with gaping holes in the fuselage. (More than a few B-52s demonstrated this when hit by NVA air defenses over Hanoi.) Wings are non-negotiable, however. 

In the specific case of that unfortunate TU-22, size is also working against them in the engineering case. To borrow from the physicists, if you imagine a perfectly spherical bomber, as the size of the sphere increases, the volume increases exponentially, as does the surface area. The surface area requires structural reinforcement running under it, and the volume must be crossed by reinforcing members criss-crossing it. There’s also the basic law of the lever, which combined with the issues of structural strength dictate that the further a point is from the fulcrum point (the support that transfers the load to ground,) the less load it can support without exceeding the lever’s structural strength and snapping it. And bombers need volume to store all the fuel and bombs they must carry. 

Now apply this to the video we saw, and you can see what happened. The TU-22′s landing might not look very hard, but for an aircraft of that size, it really is - especially if it still has significant amounts of fuel on board, increasing the weight. When it hit the ground its downward velocity was completely halted; imposing a brief but high G-load surge. You can tell how hard the aircraft hit by how it visibly bounced off the runway on contact. G-loads are effectively multiplying the weight of an aircraft, and larger aircraft will generally have lower G-limits before structural failure, so what qualifies as poor technique that abuses your poor Cessna is considered much harder when it’s a 757 pogo-sticking down the runway.

The bad news doesn’t stop there. The speed of an aircraft hitting the runway has even more of an impact on the effective g-load (remember, kinetic energy is mass times velocity squared,) and the TU-22M has relatively high landing speeds. Take a look at the design: 

This is a high-speed supersonic bomber, so it has small, highly-loaded wings. They are swing-wings, which helps considerably, but the lower lift-to-weight ratio (i.e. wing loading) means the aircraft has to be moving faster to generate X amount of lift, which translates to a relatively high landing speed compared to something like an airliner. 

Putting all this together, you can understand why a bounce that qualifies as “very hard landing” in a 757 is an airframe-destroying event for a high-performance supersonic bomber. This is a prime example of why military aircraft have been fabled as pilot-killers since their inception; every design choice that makes them high-performance also narrows the safety margins, especially in the most dangerous parts of flight; take-off and landing. In that Tupolev’s case, the initial structural failure was exacerbated by how quickly it happened. If the plane was slowing down on the landing roll, the plane might’ve sagged as it broke in half and ground along the runway, setting it afire and giving the pilots a chance to eject safely. But since the aircraft was bouncing airborne, the shifting center of gravity and loss of weight (as the fuselage bent, it was not transmitting its load to the rear of the plane,) make the rear pitch up, as the lift of the wing’s fixed pitch is adjusted to balance the whole plane, not just half of it. That caused the whole thing to fold up in a hurry, and it was all over from there. 

Maintenance issues might well have been responsible for this, but it was probably a failure of instruments, not a weakened airframe. The bad blizzard conditions visible in the video are likely the main reason for the accident - as you can see from the above graphic, a TU-22 has very poor cockpit visibility to begin with (a common problem on many aircraft, esp. military ones,) and the blizzard eliminated what little was left. The warning lights that indicate the glide path were definitely not visible, which means the pilot was probably relying on their instrument landing system. 

Instrument landing systems are very simple and robust tech first invented in the 1930s, requiring nothing digital to operate; you can find them standard in ye olden Cessna 172 RGs worldwide. It’s a simple “beam riding” system; using directional radio beams to guide a pilot into landing. Even modern HUD systems on advanced fighters use the same two crosshair needles on their display, just like the physical cross-hair needles on a Cessna’s instrument gauge, to tell the pilot where he’s at. They can bring an aircraft in to landing completely blind, although the pucker factor is very high, as this HUD tape from a night carrier landing shows. It’s rare for these systems to malfunction or break, but if there was an issue throwing off the readings, it’d fly that pilot into the ground too fast.

Another possibility is an age-old enemy of pilots - ice. Icing up of the pitot tube, which measures an aircraft’s airspeed via the airflow into the tube, has been the source of many, many aviation accidents, especially when the data was acted upon by an autopilot before the human pilots could react (or even resisting the human pilots; do not fly on an Airbus.) These many lethal accidents have resulted in fixes, of course, but a slight error might not be noticed. And then there’s the altimeter - the basic altimeter operates on air pressure, so it tells you height above sea level, not the ground (you have to keep track of that yourself.) Air pressure also changes with temperature and weather conditions, so you have to calibrate for that, as well. But advanced military aircraft have radar altimeters, which bounce a radar signal off the ground to get nice, accurate feedback without dicking about; if that system had an error, a malfunction, or was just impeded by weather (ice on a runway can reflect radio waves in funny ways), would result in inaccurate altitude readings, which in turn would give them a false reading on their climb/sink indicator, which tells them how fast they’re moving towards terra firma. 

Long story short: it is very easy to die in a military aircraft, and these poor bastards had to do it in an old Russian plane, maintained by Russians, landing at an airport maintained by Russians, in a blizzard. Of everyone who might deserve blame, I expect the airframe techs are third to last, pilots second, and Tupolev corporation itself dead last.