[Closed] You know the whole aeroplane on a treadmill question?

I can't be bothered thinking about it. What's the correct answer?

I can't be bothered thinking about it. What's the correct answer?

Once the treadmill is moving sufficiently fast to overcome the thrust of the aircraft, the aircraft will be spat off the back of the treadmill and the video will be sent to Harry Hill.

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

If only they'd tied it on to the plane...

It's the same as saying, can a hovercraft travel up a river?

The answer is yes, it can.

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

In Soviet Russia, plane moves air...

[img] [/img]
[img] [/img]

(not technically an aeroplane but answers your question)

Ekranoplan is strong, like bear 😀

It's the same as saying, can a hovercraft travel up a river?

Not at all. An airplane has wheels that touch the treadmill, a hovercraft flies above the river and doesn't touch it.

yet graceful, like eagle...

Ekranoplans are essentially just aircraft. They just have more lift to play with thanks to always flying in ground effect, although iirc the Russians did sometimes use lifting engines to help get them out of the water.

There are some very cool smaller ones-

[img] [/img]

And some even cooler concept ones-

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Not at all. An airplane has wheels that touch the treadmill, a hovercraft flies above the river and doesn't touch it.

The hovercraft is only slowed down by a bit of drag on the skirt.

The plane is only slowed down by a bit of drag on the wheel bearings.

If a hovercraft could somehow hover perfectly without touching the river at all then the direction or speed of the river flow wouldn't alter its speed.

If the plane could be fitted with perfect friction-free bearings then the direction or speed of the treadmill wouldn't alter its speed.

Obviously such perfect conditions don't exist, but in both cases then have more than enough thrust from the engines to overcome the drag.

Yes but the original question as posed on our epic thread (unintentionally) placed constraints on the hypothetical situation which meant that the bearings had drag and could survive being turned fast enough for their drag (and the tyres) to cancel out the thrust of the engines.

Ok, what about a sea plane, floating down a river, if the flow was fast enough, could it take off?
Just kidding, im with njee on this.

Yes but the original question as posed on our epic thread (unintentionally) placed constraints on the hypothetical situation which meant that the bearings had drag and could survive being turned fast enough for their drag (and the tyres) to cancel out the thrust of the engines.

pretty sure that's a red herring, too. The fictional feedback runway only goes backwards as fast as the plane is going forwards, not hundreds of times the speed, so at 747 takeoff speed of 170-190mph, the wheel bearings only have to cope with speeds of twice that, which they'd be more than capable of without seizing or bursting into flames.

Yeah, but, could desperate Dan really blow the sail boat HE WAS ON forward by blowing into the sails...?

DrP

And can you jump in a lift that's in freefall in a vain attempt to avoid certain death in a lift-cable-failure-based death?

Short take off and landing:

😆

So, if I'm in a hot air ballon, will I feel any wind against my face?

What was the original vague easy-to-misinterpret phrasing of the question, out of interest?

Science/physics/understanding stuff isn't really my strong point......are Graham S and Njee agreeing? 😳

Can't believe that I've never heard of this before....is it an stw phenomenon or a wider internetzinternetz thing?!

In answer to Molls question about how does the float plane get to the landlocked airstrip, it's sometimes this;

Looks iffy to me 😯

So, if I'm in a hot air ballon, will I feel any wind against my face?

pretty sure that's a red herring, too.

What was the original vague easy-to-misinterpret phrasing of the question, out of interest?

The question is oft repeated in different forms, but the wording is important. Sometimes people say that the conveyor belt is going backwards at the same speed the plane's going forward, imagining that this would cancel out. But in that situation, Ned's correct - the wheels would only have to handle double the takeoff speed and the plane would clearly fly.

However, when it was posted on here, the sentence said "the conveyor belt is going in the opposite direction at such a speed as to cancel out the forward motion of the plane". The only conditions that would meet that statement is if the belt was moving so quickly that the friction from tyres and bearings would cancel out the jet engines thrust, meaning the plane is stationary meaning no takeoff. And we know that the wheels and tyres can ahndle it because the statement says the belt IS moving at that speed.

Yeah, but, could desperate Dan really blow the sail boat HE WAS ON forward by blowing into the sails...?

This made my head hurt when I first saw it:

mornington crescent

[quote=pdw ]

Yeah, but, could desperate Dan really blow the sail boat HE WAS ON forward by blowing into the sails...?

Aargh, beaten to it - that was exactly what I thought of when I read that.

Though to come back to treadmills, this is one which will really do your head in involving a model of the DDWFTTW vehicle - a vehicle without internal power source which moves forwards on a moving treadmill (must get round to making myself one):

are Graham S and Njee agreeing?

Yes we are. The plane takes off. The treadmill makes negligible difference.

Can't believe that I've never heard of this before....is it an stw phenomenon or a wider internetzinternetz thing?!

It's a internet thing that's been doing the rounds for a while. I think the original STW thread on it was about seven years ago.

Now don't make me post the boy/girl problem again 🙂