Dont buy HDD's or other fraglie things from play.com

[Funkstar]

However:

Stewardess Survives 33,000ft Crash!
http://www.super70s.com/super70s/tec...ugoslav%29.asp
http://en.wikipedia.org/wiki/JAT_Flight_367

Interesting reading!

However, as you can die by falling badly from just a couple of feet (from a stationary platform yet along a plain hurtling to the ground), that stewardess is by no means a reliable sample of data

[jim]

Interesting reading!

However, as you can die by falling badly from just a couple of feet (from a stationary platform yet along a plain hurtling to the ground), that stewardess is by no means a reliable sample of data

Yeah, but I've heard a few examples of people surviving high altitude falls, although I agree it's probably very rare. As before, I guess a lot depends on where you land... water, rock or dry ground would give you virtually no chance I would think. Maybe thick snow, marshes or somewhere with a lot of foliage would give you more hope.

That was why I said "vague chance of survival" in my first post - because of examples like this. Given the evidence though, I'd say it's no replacement for a parachute

[bsodmike]

Yup, Snooty's second reply was what I was going to say as well.

That really covered it!

Now that you're not attached to the plane wing, your speed will also drop to terminal velocity where drag = weight, so you'll move even further away from the plane. Then we move onto the splat scenario.

The splat scenario obeys projectile motion. Also, you didn't mention if the aircraft was in a nose-dive or was heading into a belly-landing type crash. The projectile motion would be more obvious in the latter case of course



....and splat.

[Kumagoro]

Just to let you know, I am sending the latest one back. This time I will be getting a refund.

[jim]

Just to let you know, I am sending the latest one back. This time I will be getting a refund.

Eh? What?

Oh, right. Hard drives.

Maybe we were ever so slightly off topic .

[steve threlfall]

[finlay666]

Yes, it's been proven (and can be explained with simple mechanical mathematics)

[jim]

Yes, it's been proven (and can be explained with simple mechanical mathematics)

I'll bet that the answer is "It depends". That's always the answer

[TooNice]

Hey guys, thanks for the explanations (especially snootyjim).

I've heard those miracle survival stories, but I never really doubted that in all likelihood, my scenario would result in nothing less than a 'splat'. Though I've accepted the result as common sense I couldn't work out the logic behind it. In my mind, the reason you can drop from 1m and not be injured is because your body still hasn't accelerated enough to be a danger. So when you jump, your body body accelerate upward, slows down, stops, before accelerating downward.

So I was thinking that when you jump leap off a falling plane, the process would be the same: assuming you can get your feet off the 'ground' (e.g. wing), you would be able to cancel out the downward acceleration of the plane. I found some logic in the thought that the downward acceleration after a jump is only dependant on the distance between the you and the ground, so by leaping off at 1m off the ground, the body would only have the time to accelerate for that 1m ('magically cancelling the plane's falling velocity').

Yeah, I knew it was rubbish, but I couldn't explain why to myself.

So thanks again guys, and sorry again for taking this thread off topic

[finlay666]

I'll bet that the answer is "It depends". That's always the answer

Nah it was proven on Mythbusters

It's all down to the fact the wheels on the plane have no force behind them, the only thrust is generated from the engines which propels it forwards The planes forces act on the air, not the ground
Episode 97
http://mythbustersresults.com/episode97

http://www.straightdope.com/columns/...plane-take-off

[jim]

Nah it was proven on Mythbusters

It's all down to the fact the wheels on the plane have no force behind them, the only thrust is generated from the engines which propels it forwards The planes forces act on the air, not the ground
Episode 97
http://mythbustersresults.com/episode97

http://www.straightdope.com/columns/...plane-take-off

Yeah I saw that episode, although I was far from convinced because it seemed a bit of a half-arsed job.

The reason I said "it depends" is because as far as I'm concerned it all depends on the speed of the conveyor and the friction of the wheels. Sooner or later their resistance to motion will negate the thrust of the engines... or rather they'd catch fire and fall off. But anyway...

[bsodmike]

That assumes that the falling object is infinitely hard though, doesn't it? In practice if you drop a hard disk 1m onto a granite floor you will dent it. If that dent is 1mm or more, which it most likely will be, all the parts of the hard disk that did not directly impact the floor will experience a deceleration of <1000g.

I've highlighted a portion of what you said; it would therefore be safe to assume that the point of impact will therefore experience the idealised deceleration (that of an infinitely hard object), while the rest of the object will experience a much reduced deceleration (~1/100).

I seem to be visualising a contour plot, akin to those you seen in FEA analysis software etc, with the 'stress/strain' experienced from the impact propagating radially throughout the body from the point of impact. I'm sure there *must* be some software out there to visualise this; possibly AutoDesk Inventor, Pro/E or SolidWorks could do this?

[Kata]

Yeah I saw that episode, although I was far from convinced because it seemed a bit of a half-arsed job.

The reason I said "it depends" is because as far as I'm concerned it all depends on the speed of the conveyor and the friction of the wheels. Sooner or later their resistance to motion will negate the thrust of the engines... or rather they'd catch fire and fall off. But anyway...

My god, if you knew how many times this question has gone around on the pilot forums...

The answer is very simple and obvious, because you can assume the wheels are frictionless. In reality, the difference in friction between them rotating at a speed equivalent to 100kts (normal takeoff speed, say), and 200kts (the speed they'd be going when the plane hit 100kts on the conveyor belt thats going the other way at the same speed), is negligible.

Now that we take the wheels as frictionless, the answer is no different to a normal takeoff - the aircraft lift, and thrust, are independant from the ground (they both come from the air) and hence the conveyor belt is an irrelevance!

[mikerr]

Those who think the conveyor belt would make any difference need to think about sea planes....

[Funkstar]

Guys, please, lets not go there again!