TOPIC: Airplane Airspeed/Groundspeed Conundrum?

wolfy wrote:


I did not mean to disrupt the conversation on this new thread, Wolfy,
and I very much hope the debate will be again as lively as it was before.

I put up a note on the other thread, so that everybody, who is really interested
in this subject will find the way to this place easily and I look very much forward
to further - perhaps - controversial but civilised and constructive discussion.

.

So the "score" so far:
3 people say the airplane doesnt take off, each in their own words;
Rodin, Frothy and me

Wolfy says it does take off and was able to convince novum of that idea.

Would be good to have a poll and more insights from others on this interesting thought experiment.

*Note; as I understood the proposed idea, the conveyer belt is running against the take-off direction of the airplane.

Answer me this....

If you put a conveyor belt under the trailer part of this truck - under the 3 rear axles only - and try drive forward while opposing the speed youre driving at with the conveyor, what happens?

novum wrote:
Yes, Of course I can see what you are getting at now, this is what I explained to you earlier in the thread and you conceded the point, I think this thread is confusing you Nov.


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Gaia wrote:
I find it comical that even after the conundrum has been explained our three resident geniuses still can't see it, or are still squirming

novum wrote:
The pitot doesn't need to work in a vacuum, as soon as it hits the earths atmosphere there is no vacuum.

I will ask the same question again from earlier in the thread:

At what point in your head would the shuttle lose the resistance against the earths rotation?

if you accept the shuttle would meet more resistance travelling against the atmosphere why not the aircraft?

The atmosphere becomes stronger the closer the shuttle gets to the earth.


To flesh I out a bit, the shuttle goes from maximum resistance to no resistance.

Why does the supersonic aircraft always stay at no resistance no matter which way or where it flies?

novum wrote:
I've had another think about it and you're right about the plane and the conveyor belt.

The Earth spins at about 465 metres per second, I won't walk that 5k to visit my imaginary aunt I'll just jump up and down a dozen times and be there in a few seconds

Wofly-son, in the air travel is the same speed in any direction, the atmosphere travels at about the same speed as the Earth, otherwise you get the scenario above.

Rat wrote:
You're not understanding the issue here frothy.

if you jump, you have no thrust.

Everybody knows a stationary object, whether it's a wind sock or whatever is stationary wrt the earth and its atmosphere.

See the puzzle about the shuttle and the supersonic aircraft above.

wolfy wrote:
Which specific post is this puzzle on, I've looked back and forth but must have missed it?

Ah you mean this

Wolfy worte

I don't know exactly where the resistance to the Earths rotation would be lost, I guess it depends on shuttle speed and other influences, the resistance that you speak of is mainly caused by a combination of gravity and centrifugal force. The shuttle resistance is caused by breaking into the atmosphere, the resistance is not there when you're already going round with it.

If the moon is rotating from the Earth, it gives some indication how far the rotation continues, it just gets weaker and weaker until atoms are no longer influenced by the Earth at all, the nearer something gets to Earth the faster it will rotate depending on weight mass etc, until it's into the regular Earth's atmosphere, the shuttle will need to cut a path through the rotation this becomes harder the nearer it gets to the Earth's surface, when it starts rotating with the Earth it no longer puts up any resistance.

Actually you could imagine an aeroplane as being attached to the Globe with a piece of string, it's being spun , now on that string the plane can move back and forth the globe, it either speeds up to get from A to B, or it turns around and speeds up to get from B to A, otherwise it's still and would fall from the sky.

wolfy wrote:
This thread began as airplane airspeed/groundspeed conundrum... i feel that question has been answered by my previous post, which also explains why you dont need more power, and why the instrumentation doesnt read more or need to read more.... in order to travel either direction relative to earths direction of rotation.

I also think that the statement about "losing resistance against earths rotation" is somewhat erronous as is stating a shuttle meets more resistance travelling against the atmosphere than an aircraft...

...i dont think anything is "losing resistance against earths rotation" ... aircraft are simply subject to earths rotation, as is a shuttle.

... but a shuttle is subject to different forces on its descent than any aircraft would be, until it is eventually inside earths atmosphere, at which point it is subject to the same forces as an aircraft.

At the point a shuttle is subject to the same forces as an aircraft is obviously when it is inside earths atmosphere at an altitude comparable to a plane. You seem to want to call this point the point where you "lose resistance to the atmosphere" .. im thinking this statement is somewhat erronous as ive just said.

Now im no space engineer so i looked this up.. this is how a shuttle enters the atmosphere



The above seems to be the consensus on various sites explaining re-entry. So a shuttle apparently enters gently in a spiral... if this is indeed the case then you could say it gradually gets to a point where its subject to the same forces as a plane.

wolfy wrote:
Again, i feel the statement "no resistance" is erronous.... there are obviously forces involved with air travel, so it then becomes about which forces do you need to counter and by how much, to get from point A to point B on the earths surface.

And a plane requires the same amount of energy to travel the same distance either way versus the earths rotation (ignoring any additional winds obviously)... i feel that has been demonstrated in the thread now.

A shuttle is entering the earths atmosphere so it has to traverse from no atmosphere to atmosphere, its coming down from outside the atmosphere into the atmosphere different forces and vectors are involved. Ive written about re-entry just above.

wolfy wrote:
Well i think the forces required to move either way are the same, hence the pitot reads the same, and that this has been demonstrated... yet thats still confusing you.

And like ive just said, i dont think anything "loses resistance to earths atmosphere" ... i just dont think thats the right way to explain anything, imho.... id say there are various forces involved and any movement of an aircraft (or shuttle) ... in relation to a point on earth/the ground is subject to the sum total of those forces.
wolfy wrote:
I see frothy has conceeded now.

I guess sometimes we can all be a bit like Fonzie.

Just another point... consider this thought experiment...

Wolfy, imagine you released a pitot into the atmosphere, and the atmosphere is moving at 1000mph as per earths rotation... and the pitot is caught in the atmosphere and moves with it at 1000mph, (lets assume for our little experiments sake it could stay orientated the correct way in order to read against earths rotation)

I think we can both agree it wouldnt read anything... nor would an automotive air flow meter in this scenario. In both cases, there is no pressure differential anywhere in the pitot or air flow meter. The pitot is caught in the atmosphere and moving with it.

Now... imagine you are a god (easy for me ) ... and you were chilling in space outside of earth sitting in the same spot not moving, but orbiting the sun together with earth and watching earth spin, and stuck your god hand into the atmosphere and held that pitot absolutely still against the atmosphere.

Air is now crashing into the pitot at 1000mph. It would read 1000mph.

This is what a plane has to do in order to move at 1000mph relative to a point on the ground when it wants to travel against earths rotation... it must add that amount of power/thrust counter the earths rotation.

Its now doing 1000mph vs the ground, and the air going into the pitot is still only 1000mph.. its not 2000mph.

wolfy wrote:
Scenario 1

Conveyor belt imparts thru the wheels some form of backwards force that balances out jet thrust. Obviously the brakes would have to be partially applied. Then the plane would push against air but not be able to move forwards hence gain lift

Scenario 2

Conveyor belt imparts thru the wheels zero force, because the wheels are freewheeling. Obviously the conveyor plays no part in the plane's take-off, no different from a runway. maybe burst tyres due to excessive spin speed, melted axles etc

Oh i know pfiz will hate some of these posts.

Pfiz, im basing my posts here on the mainstream HC model for argments sake.

I did read your post about the ships hull showing at over 8km away.

novum wrote:
This

truth-zone.net/forum/science-and-physics/67805-airplane-airspeed-groundspeed-conundrum.html?start=80#229479

should be in her thread.

Over-the-horizon sightings are useless for calibrated measurements of curvature, due to the variable refraction of the Earth's atmosphere. eg we can still see the Sun after it has actually dropped behind the horizon (in a clear sky of course)

ok i moved that post now, its in the other thread.

novum wrote:


Why should I "hate" posts? There is nothing wrong with discussing commonly accepted explanations controversially,
and if there are only contrarian views and no proponents of the mainstream dogmas, there's nothing controversial about
the discussion and vice versa.

And I guess you did understand why this should be impossible,
but maybe you are a believer of rodin's system induced religion.




rodin wrote:



This thread became very slow after the comments were removed from the concave earth thread ....
does this mean you all suddenly agree now? If so, on what exactly?



.

PFIZIPFEI wrote:
My comments about the pitot speed readings make sense to me (why it wont read more one way than the other), and the 'hand of god' comment is putting it about as simply as i could, i think.
PFIZIPFEI wrote:
Is he wrong about refraction and observed phenomenon with sunsets though?

That is an accepted phenomenon in mainstream science.

Here is an interesting discussion, it goes over atmospheric refraction but also delves into other things regarding the nature (shape) of earth...

www.metabunk.org/atmospheric-sunlight-refraction-arguments-on-the-eratosthenes-triangulation-method.t7801/