[request] Assuming fresh powdery snow, how deep would it have to be for the paratrooper to survive, if possible?

[u/Fizzerolli]

My son sent me this. My immediate thought based on nothing is that it’s unsurvivable regardless of the depth.

[u/SoylentRox]

Note the skydiver doesn't have to be going terminal velocity. Potentially the drop could be from, say, 100 feet up, right at the stall speed of the 1940s Soviet transport aircraft used. At impact with the deep snow the skydiver will be traveling at ? m/s, or ? mph

Say it's 50-60 mph, for the Lisunov Li-2, a Soviet copy of the DC-3, which has a stall speed of 51 mph. Then at impact

v = sqrt[(v_0)^2 + 2gh]

Where:

  v₀ = initial speed (stall speed ≈ 27.7 m/s)
  g = 9.81 m/s² (gravitational acceleration)
  h = height (100 ft ≈ 30.5 m)

At impact, without drag, they will be traveling about 37 m/s or 83 mph.

I also tried a python script to model the speed vs time to take into account horizontal drag. I get

Impact results:

x: 61.19 m, y: -0.00 m

Horizontal speed: 18.97 m/s

Vertical speed: -21.59 m/s

Total speed: 28.74 m/s, which is ~64 mph

Then if the person, impacting at 64 mph, decelerates over 1m through the snow, they are subject to 42G of deceleration, which is on the edge of survivable.

About 5-10% of soldiers might survive this.

I am hoping the Soviets did experiments with dummies of the instrumented non living kind to test this before trying actual soldiers...

[u/CaptainRex8669 → u/SoylentRox]

The Soviets did lots of parachuting with the AN-2, which is famously impossible to stall. The POH doesn't have a stall speed listed within.

The slowest speed the aircraft has been flown at is 26 knots, and the controls remain responsive at that speed. Keep in mind, this is airspeed, not groundspeed. If they fly in a strong enough headwind they could achieve a groundspeed of 0, or even fly backwards.

[u/Lathari → u/CaptainRex8669]

The operating handbook does not explicitly specify a stall speed, stating instead: "If the engine quits in instrument conditions or at night, the pilot should pull the control column full aft and keep the wings level. The leading-edge slats will snap out at about 64 km/h (40 mph) and when the airplane slows to a forward speed of about 40 km/h (25 mph), the airplane will sink at about a parachute descent rate until the aircraft hits the ground."

TFW POH states the correct thing to do when engine quits is to pull on the controls and wait.

[u/CaptainRex8669 → u/Lathari]

That's hilarious. Try that in ANY other aircraft and it will kill you.

[u/Lathari → u/CaptainRex8669]

As the old joke goes:

If you push the stick forward, the houses get bigger. If you pull the stick back, they get smaller. That is, unless you keep pulling the stick all the way back, then they get bigger again.