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Member postings for ted hughes

Here is a list of all the postings ted hughes has made in our forums. Click on a thread name to jump to the thread.

Thread: A question of physics.....
14/10/2016 01:13:54
Posted by Gary Manuel on 12/10/2016 21:12:31:

Yes - as long as the conveyor is long enough.

The 747 is driven forwards by the jet engines, not the wheels.

The wheels / conveyor might be turning, but that is irrelevant.

As long as the conveyor is long enough?

Not university educated, I hazard a guess?

14/10/2016 00:58:24

It has been fun, but I give up.

It is a question of logic, not common sense or physics.

14/10/2016 00:57:18

Gary, when the plane provides thrust, its wheels will turn.

The conveyor belt matches the speed of  that turn.

The plane remains stationary.

It can't fly.

It is a logic puzzle, not a physical one.

I give up on this.

Edited By ted hughes on 14/10/2016 00:59:02

14/10/2016 00:37:49
Posted by WolstonFlyer on 14/10/2016 00:33:57:
Posted by ted hughes on 14/10/2016 00:29:55:

You'll never get it, will you?

It is a logic puzzle.

Me ted?

I get it, I started the thread.

Of course it is a puzzle, that's why I posted it, lots of interesting comments so far. My mobile phone has been going crazy with the emails all day

Edited By WolstonFlyer on 14/10/2016 00:34:28

Fun thread, I enjoy it!

14/10/2016 00:29:55
Posted by WolstonFlyer on 14/10/2016 00:18:04:

Opposite to the rotation of the wheels Stuart, if the plane wheels are turning anti-clockwise then the rollers on the conveyor are turning clockwise.

Still having fun?

@ Martin McIntosh- No I didn't fly the Tucano yet, it is almost finished and then I went and changed jobs and some other stuff that has pulled me away from building models for a while. But it will get finished!

The wheels are turning as per normal for forward speed.

You'll never get it, will you?

It is a logic puzzle.

14/10/2016 00:28:08

It is a logic puzzle, which is not respectful of common sense or physics.

One of the earliest was Aeschylus and the tortoise.

The tortoise was given a 100m start in a race.

By the time Aeschylus had reached 100m, the tortoise had moved on.

When he reached that new point, the tortoise had moved on again, and so on ad finitum. So he never can overtake the tortoise.

We know it cannot be really possible, but that is the logical solution.

The plane cannot take off because it remains stationary.

13/10/2016 23:57:46
Posted by Bob Burton on 13/10/2016 21:02:05:

Why so much discussion ?

The conveyor matches the speed of the wheels moving in the opposite direction therefore the plane will never move forward so will never take off from the conveyor belt.

This is the correct answer to the problem.

13/10/2016 23:54:48

When the contestant was asked to choose the first time, he was guessing one in three.

The second time, he was guessing one in two.

So it was always wiser to guess again!

13/10/2016 23:46:54

A very interesting thread, reminds me of the Monty Hall problem, which had top academics laying their mathematical accreditation on the line.

Monty Hall was an American game show host.

At the end of the game, the winning contestant was shown three doors.

Behind one was a car, behind two, goats.

The contestant was asked to choose a door (lets say he chose B, out of A, B and C.

Monty Hall then opened one of the remaining doors to reveal a goat.

The contestant was then asked if he wanted to change his mind and choose the remaining door to try to win the car.

The question posed to the world was: would changing your mind improve your chances of winning the car, or was the original choice as good as any.

The logical and correct answer was that changing your mind gave a 33% better chance of obtaining the car- but many academics could not see this.

13/10/2016 23:37:32
Posted by Colin Leighfield on 13/10/2016 23:01:47:

The wheels don't drive the movement of the plane, their rotational speed is only relevant to the difference in speed between the conveyor and the plane. Whether it flies or not is purely a function of its' speed relative to the air. That is purely dependent on the balance between engine thrust and airframe drag. What the conveyor is doing has no influence on that, all it influences is the speed that the wheels rotate at.

The plane won't have any air speed because it is not moving. It is a logic puzzle.

13/10/2016 23:36:21
Posted by Stuart Coyle on 13/10/2016 22:29:48:

The conveyor matches the wheel speed - not the axel speed. The plane takes off with very fast spinning wheels, since no amount of wheel speed will cause retardation of the a/c. ( Hence the conveyor has the same dimensions as a runway).

The plane may well have fast spinning wheels, but the conveyor always matches them. It is a logic puzzle, not a matter of physics, despite the thread title.

13/10/2016 21:09:28

You are right, Bob, but others are getting confused thinking the conveyor belt is matching the speed of the aircraft, which was not in the original question.

13/10/2016 20:55:45
Posted by Dave Hopkin on 13/10/2016 20:20:13:
Posted by ted hughes on 13/10/2016 20:04:00:

It would not fly.

Imagine the conveyor belt started with the plane not using its engines for thrust.

The plane would stay stationary, just the wheels would spin.

As soon as the plane used thrust, it would move backwards if the conveyor belt was faster than the thrust could provide, but if they were balanced (as in the problem), the plane would be stationary.

Edited By ted hughes on 13/10/2016 20:04:37

Apart from the facts

a) the wheels of the plane are not driven so what happens at the wheel/ground interface is irrelevant

b) Mythbusters put the conundrum into real life... guess what the plane flew....

**LINK**

 

Now can we let this thread die ?

Because you are wrong. I know it is hard to understand.

The myth busters were working on a different problem.

They were matching conveyor belt speed with speed of the plane.

The OP problem did not mention speed of the plane.

It is concerned with the speed of the wheels, which is quite a  different problem.

 

Edited By ted hughes on 13/10/2016 20:56:55

13/10/2016 20:04:00

It would not fly.

Imagine the conveyor belt started with the plane not using its engines for thrust.

The plane would stay stationary, just the wheels would spin.

As soon as the plane used thrust, it would move backwards if the conveyor belt was faster than the thrust could provide, but if they were balanced (as in the problem), the plane would be stationary.

Edited By ted hughes on 13/10/2016 20:04:37

13/10/2016 16:41:44

It is a hypothetical question, real issues like friction etc. don't come into it.

The plane can't move forward, because the belt is moving backwards to match its forward speed all the time.

Imagine no belt, it is just the runway and the earth moving backwards beneath the plane, increasingly fast- the plane will not move relative to the earth.

Edited By ted hughes on 13/10/2016 16:42:26

13/10/2016 15:20:53

The plane can't take off.

It can't move forward, so there will be no lift.

Thread: Complete beginner - recommendations please
10/09/2016 11:20:56

Apparently many, many people have learnt on the Hobbyzone Champ, despite it's small size.

It's lightness means it bounces rather than crashes:http://www.ebay.co.uk/itm/HBZ4900-Hobbyzone-Champ-RTF-Ready-To-Fly-Starter-RC-Radio-Control-Plane-New-UK-/172112920056?hash=item2812babdf8:g:GbMAAOSwB4NWzaEm

Edited By ted hughes on 10/09/2016 11:21:46

Edited By ted hughes on 10/09/2016 11:23:50

Thread: HDMI Cable Repair
21/08/2016 22:51:58

**LINK**

Thread: What's flying over your house
19/08/2016 08:38:12

Very disappointing weather forecast for Bournemouth today. Lets hope it clears enough to get something into the air!

And yesterday was a perfect day for the Air Festival.

Edited By ted hughes on 19/08/2016 08:39:00

Thread: Recommendations for good first model for FPV / Air to air video
12/08/2016 14:13:21

Sorry folks for posting that video.

I was considering the tutorial value of it showing how to set up the equipment, and also suggesting that plane to the OP.

I did not consider that it was showing a bad example by flying outside the law- I should have.

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