Well here, courtesy of some talented Canadians, is a hint of an answer… 😯

Float plane takes off from concrete runway on the back of a truck:

[video]https://www.youtube.com/watch?v=7osw2jcsi6Q[/video]

you’re going to have so many people tell you that it’s not the same as the treadmill thing…

I may even be the first.

Not the same S_R. Plane is moving forward and so has air moving over the wings. Plane doesn’t move on the old treadmill question.

Nice try though 😉

EDIT: Dammit! 🙂

Not the same at all.

Well the truck’s moving forward an it doesn’t take off.

Go figure.

Lol, air moving over the wings will generate lift so it will take off. No air flowing on the treadmill.

Ya ya, I know. I stand by the fact that it’s still pretty cool, though.

Nice vid! The only reason the treadmill question is so fun is that there are loads of ways of interpreting it, plenty (most/all, if you ask me) involve the aircraft moving forward and air over the wings.

You know the whole aeroplane on a treadmill question?

No, what is it?

The airplane on a treadmill thing is a problem because it’s a nonsense question as usually phrased.

The idea is that the treadmill goes backwards at the same speed as the plane goes forwards – using some feedback system. That would work fine with a car where the road wheels are driven, it’s a nonsense with an aircraft.

Worst. Episode of Tales of the Gold Monkey. Ever.

once upon a time…

Not the same S_R. Plane is moving forward and so has air moving over the wings. Plane doesn’t move on the old treadmill question.

Of course the **** plane moves, the wheels aren’t powered! Put a model car on a treadmill whilst you stand beside it. Can you push the car forward off the treadmill? Of course, you can push it wherever the hell you want, because thrust doesn’t give two shits what the wheels are doing. The treadmill can be moving backwards at 4 billion mph for all I care, the wheel bearings may get a bit toasty, but that’s it!

IMO anyone who can’t comprehend this is a total cockwomble and should be sterilised before they procreate.

trifle harsh njee, but essentially true.

it’s not a nonsense question, it just teases out gaps in understanding.

Another way of asking would be “what kind of aircraft wouldn’t be able to take off on this (described above) kind of magic feedback treadmill?”

and the answer is the kind of aircraft that has no way of powering itself forward once off the ground i.e. not an aircraft, or a glider – ask it again with “glider” in the question…

should be sterilised before they procreate.

Too late, already done that. I still don’t understand though, can you draw me some nice pictures njee? No big words though, they hurt my brain. Ta

ask it again with “glider” in the question

Aaah yes, so if you ask a different question entirely then the answer is different? 🙂

Too late, already done that. I still don’t understand though, can you draw me some nice pictures njee? No big words though, they hurt my brain. Ta

Take my ‘car on a treadmill’ example. If you stuck a model car on a treadmill, then turned the treadmill on at 5mph whilst standing beside it, and held the car, what happens? The wheels turn (at 5mph), the car doesn’t move. Now push the car forward (like thrust on a plane) what happens? The car moves forwards, the wheels are now rotating at the airspeed + 5mph, or the groundspeed is 5mph greater than the airspeed if you prefer.

This is what a plane does. You can keep pushing the car forward, no matter how fast the treadmill is moving, because the power is not applied through the wheels.

You would still need a 10,000′ treadmill to get a 747 to take off – they can’t take off on the spot or anything daft (which I think is often the misunderstanding), but it also won’t stay in one place as soon as they apply some thrust.

Woody, because the planes wheels can move at any speed in response to the treadmill – like a set of roller bearings. What is giving the thrust, are the propellers or jet engines.

ask it again

oh god

make it stop

I can appreciate that perhaps the float plane is at the landlocked airport because it needed some kind of repair. But how did they land it there in the first place?

Don’t give me some kind of boring answer like it was built there or arrived in pieces. I want to see it land on a moving low loader!

You would still need a 10,000′ treadmill to get a 747 to take off

Can we put all the people still talking about this, directly behind the 747, while it takes off?

I’d settle for ‘just in front of the intakes’ as well.

It had wheels on when it landed and was converted to a float plane at the airport.

It’s in the youtube comments innit!

Aaah yes, so if you ask a different question entirely then the answer is different?

yes, once you’ve tightened up all the areas in which a question can be misunderstood, you end up with a boring question with an obvious answer and no entertaining discussion. 😀 😐

What if you 2 treadmills so the first treadmill was going backwards, or sideways?

Nice explanation njee – I think I understand

What if you ditched the treadmill and used a giant fan to blow air over the wings? 😉

It had wheels on when it landed and was converted to a float plane at the airport

I demand youtube satisfaction!

[video]https://www.youtube.com/watch?v=AoY-J0SkA3U[/video]

Crowd is clearly impressed ^^^

I’m writing to Danny McAskill.
I want to see him fly over a huge jump and land perfectly on a Thule 591 roof carrier on top of a moving Audi.

What about a fly in a car?

I want to see him fly over a huge jump and land perfectly on a Thule 591 roof carrier on top of a moving Audi.

😆

I can appreciate that perhaps the float plane is at the landlocked airport because it needed some kind of repair. But how did they land it there in the first place?

They have retractable wheels in the floats so they can touch down on land or water. However if landing on water you do need to remember this point and make sure the wheels are up…

[video]https://www.youtube.com/watch?v=-48V1m_MZxE[/video]

What if you ditched the treadmill and used a giant fan to blow air over the wings?

That’s called a wind tunnel. You’ll generate lift, but the plane won’t go anywhere, it can’t spontaneously transfer airspeed to ground speed. But the airspeed could notionally be the same as the ground speed would be were it flying, that being the whole point of a wind tunnel. Next.

The original one was badly phrased so it always depended on how pedantic you were as to whether it would or wouldn’t take off.

Beaten to it. I want to see a big fan!

That’s called a wind tunnel. You’ll generate lift, but the plane won’t go anywhere, it can’t spontaneously transfer airspeed to ground speed. But the airspeed could notionally be the same as the ground speed would be were it flying, that being the whole point of a wind tunnel. Next.

OK what if you attached a giant fan to the front of the plane so that it constantly pushed air backwards over the wings? 😉

its a moot question either way

Harrier jump jet …discussion end

OK what if you attached a giant fan to the front of the plane so that it constantly pushed air backwards over the wings?

Same thing.

Ignoring the aerodynamic and balance impact of the giant fan it could theoretically ‘fly’ in the traditional sense too if you turned the engines on, although the airspeed would probably exceed various limits and it wouldn’t enjoy it.

Pfft! we’ll get this plane airborne somehow!

What about a huge catapult that flings it up in the air.
Could be powerd by, I dunno, like steam or something?
Would that work? 😉

Like an aircraft carrier? Yes, that’ll work.

I’ve run out of ideas now.

Oooh….. wait….. what about if we used a compressor sort of thing to suck in air and burn stuff to heat it and expand it and expel the exhaust gases through some kind of nozzle arrangement…..

Oh hang on…… my mummy says I’ve to stop being intentionally dense in an attempt to wind up someone who is unaccountably angry about hypothetical situations and i’ve got to go in for my tea.

Sorry 😳