Is outdoor running > treadmill running?

plodder

Oisin11178 wrote: »

OMG my poor thread you animals:D
Question was if you could do say 39.30 for 10k on a treadmill with maybe 90% put in, is it reasonable to assume with the tank emptied and taper and race adreniline that you would go under 40 mins for 10k on a reasonably flat course with no brutal headwind?

if there was a plane behind you, about to take off then you probably would ... :pac:

RayCun

sean_84 wrote: »

If you have a something with free running wheels, put it on a treadmill and try move it forward and back with the treadmill set to different speeds to see how it works.

They would have to be perfectly free-running wheels, if you are trying to hold an airplane in place.

RayCun

Oisin11178 wrote: »

OMG my poor thread you animals:D
Question was if you could do say 39.30 for 10k on a treadmill with maybe 90% put in, is it reasonable to assume with the tank emptied and taper and race adreniline that you would go under 40 mins for 10k on a reasonably flat course with no brutal headwind?

Yes.
If you can arrange for a car to drive in front of you with a tv in the back showing sky sports.

TFBubendorfer

Reading this thread (well, ... skipping plenty, admittedly) I conclude that I must have been transported into a parallel universe (either by plane or treadmill, I suppose) where everyone else has gone completely bonkers and I'm the only sane person left around. :cool:

28064212

RayCun wrote: »

Hold on, so you're saying that you can hold the plane steady when the treadmill is at 1kph, but you and the plane's engine going full blast can hold the plane steady when the treadmill is at 500 kph?

What if the treadmill was going at 500kph, and the engine's weren't switched on? Would you still be able to hold the plane in place?

That was my point. I was saying replace me and my rope with the engine's power. It's never me and the engine. If I and my rope (alone) can hold the plane steady at 1kph (or whatever speed is the minimum point at which the friction of the wheels is irrelevant), I and my rope (alone) can hold it at 500kph.

RayCun

28064212 wrote: »

That was my point. I was saying replace me and my rope with the engine's power. It's never me and the engine. If I and my rope (alone) can hold the plane steady at 1kph (or whatever speed is the minimum point at which the friction of the wheels is irrelevant), I and my rope (alone) can hold it at 500kph.

Sure, given frictionless wheels.

Are we agreeing here that if the wings of the plane are moving relative to the air, it will fly, and if they're not it won't?

28064212

RayCun wrote: »

Sure, given frictionless wheels.

I specifically addressed friction in my post. When you say frictionless wheels, are you talking about wheels with a frictionless surface on them or wheels that turn with zero friction? In either case, it's impossible for the treadmill to move the plane at all, regardless of ropes or engines.

Because there is friction in the bearings of the wheels, once the treadmill starts, there is a certain minimum speed that the "forward force" (whether engine or rope) must apply to remain motionless, but that minimum speed never rises beyond a (very low) point, regardless of the speed of the treadmill

To steal the analogy of the AOAT blog above, imagine you're on a skateboard on a stationary treadmill. You turn on the treadmill at a low speed, you start to move backwards (because of the friction in the wheels). You grasp on to the bars to hold yourself in position. Now increase the speed. There is no extra effort to hold yourself in position. If you increase it to 3000kph (assuming the treadmill can do that), you will still not need any extra effort. And if you want to move forward relative to the ground, you only need to exert a tiny amount of effort

RayCun wrote: »

Are we agreeing here that if the wings of the plane are moving relative to the air, it will fly, and if they're not it won't?

Yes. But it will definitely move relative to the air once it increases beyond a certain minimum speed

RayCun

I can't believe this is still going...

Assume a mile-long treadmill (given the other assumptions, why not?) with a plane in the middle, and markers off the side of the treadmill to show the midway point.
The treadmill starts moving backwards at 1mph. The pilot starts up the engines, gives it some throttle, and gets the plane back to the midway point. Treadmill going, engine going, no movement, no lift.
The treadmill starts accelerating at a constant rate. The pilot (who has a lot of practice, and wrecked several planes and treadmills in the process) increases the throttle at a constant rate. Through some miracle of precision, he keeps the plane at the same point as the treadmill accelerates to 3mph, 5mph, 7mph.
The treadmill keeps accelerating. The pilot keeps giving the engines more power... what happens?

At some point, even though treadmill speed and engine power are increasing in synch, the plane will move forward?
The plane will stay in the same place, but lift off (and then move forward)?
The plane will stay in the same place, and not lift off?

Show your work

bart simpson

28064212 wrote: »

I specifically addressed friction in my post. When you say frictionless wheels, are you talking about wheels with a frictionless surface on them or wheels that turn with zero friction? In either case, it's impossible for the treadmill to move the plane at all, regardless of ropes or engines.

Because there is friction in the bearings of the wheels, once the treadmill starts, there is a certain minimum speed that the "forward force" (whether engine or rope) must apply to remain motionless, but that minimum speed never rises beyond a (very low) point, regardless of the speed of the treadmill

To steal the analogy of the AOAT blog above, imagine you're on a skateboard on a stationary treadmill. You turn on the treadmill at a low speed, you start to move backwards (because of the friction in the wheels). You grasp on to the bars to hold yourself in position. Now increase the speed. There is no extra effort to hold yourself in position. If you increase it to 3000kph (assuming the treadmill can do that), you will still not need any extra effort. And if you want to move forward relative to the ground, you only need to exert a tiny amount of effort


Yes. But it will definitely move relative to the air once it increases beyond a certain minimum speed

ah good post, i get ya, this minimium amount is just to overcome the friction of the wheels.......so if a plane was on a threadmill....and the thread mill was doing say 600mph, and the plane had a thrust of 300mph, well then the plane would move forward and take off moving at 300 mph...however the planes wheels would be going at 900 mph!!! am i right?

28064212

RayCun wrote: »

I can't believe this is still going...

Assume a mile-long treadmill (given the other assumptions, why not?) with a plane in the middle, and markers off the side of the treadmill to show the midway point.
The treadmill starts moving backwards at 1mph. The pilot starts up the engines, gives it some throttle, and gets the plane back to the midway point. Treadmill going, engine going, no movement, no lift.
The treadmill starts accelerating at a constant rate. The pilot (who has a lot of practice, and wrecked several planes and treadmills in the process) increases the throttle at a constant rate. Through some miracle of precision, he keeps the plane at the same point as the treadmill accelerates to 3mph, 5mph, 7mph.
The treadmill keeps accelerating. The pilot keeps giving the engines more power... what happens?

At some point, even though treadmill speed and engine power are increasing in synch, the plane will move forward?
The plane will stay in the same place, but lift off (and then move forward)?
The plane will stay in the same place, and not lift off?

Show your work

Your mistake is in the bolded parts. You've completely ignored the point from my last 2 posts. Once the plane reaches the minimum speed necessary to compensate for the friction in the wheels, it needs no more speed. If it increases the speed, it will move forward.

Read the skateboard analogy again. Then read it again. And again. Do you think I need more effort to hold myself in position at 10kph than I do at 100kph?

anymore

I recently did 2/3 miles om the road with a hill on return leg and then did approx 3.5 miles on a treadmill using inclines. There is no comparison, in my very limited experience between road and treadmill. Treadmill is by far the easier option !
Ps I would have my doubts of the accuracy of the clocks on treadmills.

RayCun

28064212 wrote: »

Your mistake is in the bolded parts. You've completely ignored the point from my last 2 posts. Once the plane reaches the minimum speed necessary to compensate for the friction in the wheels, it needs no more speed. If it increases the speed, it will move forward.

This is one of the options I gave you

At some point, even though treadmill speed and engine power are increasing in synch, the plane will move forward?

bart simpson

anymore wrote: »

I recently did 2/3 miles om the road with a hill on return leg and then did approx 3.5 miles on a treadmill using inclines. There is no comparison, in my very limited experience between road and treadmill. Treadmill is by far the easier option !
Ps I would have my doubts of the accuracy of the clocks on treadmills.

what does your running have to do with our aeroplanes and giant treadmills eh? dont be going off on a tangent!:D:eek::p

robinph

The fact that the plane can take off is cheating though, the point of a treadmill is to keep it's passenger in a stationary position relative to the earth. If the plane starts moving forwards relative to the earth, thus creating air movement over it's wings, then the treadmill is an irrelevance. If the plane is moving relative to the ground it's not following the rules of being on a treadmill, if the treadmill is a mile long and the plane moves along that mile distance then it is effectively not on the treadmill anymore.

sean_84

28064212 wrote: »

Your mistake is in the bolded parts. You've completely ignored the point from my last 2 posts. Once the plane reaches the minimum speed necessary to compensate for the friction in the wheels, it needs no more speed. If it increases the speed, it will move forward.

I think the mistake is even earlier:

The treadmill starts moving backwards at 1mph. The pilot starts up the engines, gives it some throttle, and gets the plane back to the midway point. Treadmill going, engine going, no movement, no lift.

When the plane gets back to the midway point, it won't stop there, it will keep moving forward!

28064212

RayCun wrote: »

This is one of the options I gave you

RayCun wrote: »

At some point, even though treadmill speed and engine power are increasing in synch, the plane will move forward?

Yes, it will move forward. The treadmill speed is irrelevant. What is relevant is the backward force that the treadmill exerts on the plane, and that never rises above a minimum level

bart simpson

RayCun wrote: »

This is one of the options I gave you

yeah but any extra juice put into the threadmill will only make the planes wheels spin faster....the pilot will not need to match this extra threadmill speed with his throttle by a ratio of 1:1...he will only need to overcome extra friction of wheels to move forward

anymore

bart simpson wrote: »

what does your running have to do with our aeroplanes and giant treadmills eh? dont be going off on a tangent!:D:eek::p

Apologies, thought this was the running thread
Time to get the eyes checked again !:mad:

28064212

robinph wrote: »

The fact that the plane can take off is cheating though, the point of a treadmill is to keep it's passenger in a stationary position relative to the earth. If the plane starts moving forwards relative to the earth, thus creating air movement over it's wings, then the treadmill is an irrelevance. If the plane is moving relative to the ground it's not following the rules of being on a treadmill, if the treadmill is a mile long and the plane moves along that mile distance then it is effectively not on the treadmill anymore.

That sounds more like a philosophical statement: "if a man moves forward on a treadmill, is he really on a treadmill".

If the treadmill is an infinite distance in length, the plane can still take off

sean_84 wrote: »

I think the mistake is even earlier:

When the plane gets back to the midway point, it won't stop there, it will keep moving forward!

Yep, correct, the pilot would have to reduce power. I misread it as if he was saying the plane reached a speed which rendered it stationary relative to the ground, rather than actually moving forward to the midway point

28064212

bart simpson wrote: »

yeah but any extra juice put into the threadmill will only make the planes wheels spin faster....the pilot will not need to match this extra threadmill speed with his throttle by a ratio of 1:1...he will only need to overcome extra friction of wheels to move forward

Almost, but not quite right. The frictional force does not actually increase at all, regardless of the speed of the treadmill. Once the pilot reaches the point of equilibrium (he's stationary relative to the ground), he never needs to increase his speed, no matter what speed the treadmill increases to

bart simpson

28064212 wrote: »

Almost, but not quite right. The frictional force does not actually increase at all, regardless of the speed of the treadmill. Once the pilot reaches the point of equilibrium (he's stationary relative to the ground), he never needs to increase his speed, no matter what speed the treadmill increases to

so he needs equilibrium speed plus normal take off speed to get into the air, yea makes sense

BeepBeep67

My head hurts - funny though

Aimman

bart simpson wrote: »

so he needs equilibrium speed plus normal take off speed to get into the air, yea makes sense

Nope, if he'd stationary relative to the ground, then he cant take off, because there is no air passing over and under the wing. The rapid passing of air around the wing causes lower air pressure above the wing then under it because of the curvature of the wing. The low pressure above the wing will pull the wing up and consequently pulls the plane with it, thus take off. The jet engines only make the plane go forward, the wings shape makes it take off.

What I'm interested in finding out, is what happened when the treadmill is up to that 200mile/hour speed, what happens to the plane when someone hits the emergency stop on the treadmill????

28064212

Aimman wrote: »

Nope, if he'd stationary relative to the ground, then he cant take off, because there is no air passing over and under the wing. The rapid passing of air around the wing causes lower air pressure above the wing then under it because of the curvature of the wing. The low pressure above the wing will pull the wing up and consequently pulls the plane with it, thus take off. The jet engines only make the plane go forward, the wings shape makes it take off.

But he will not be stationary relative to the ground, except at a very low speed thrust (engine power). You can't reach takeoff speed thrust and be stationary relative to the ground

Aimman wrote: »

What I'm interested in finding out, is what happened when the treadmill is up to that 200mile/hour speed, what happens to the plane when someone hits the emergency stop on the treadmill????

Assuming the plane is at the speed necessary to remain stationary? It will roll forward very slowly

thirtyfoot

The mention of thrust gets this back on topic. Running outdoors is like sex. Treadmill is like masturbating. People who prefer and always do treadmill have either never done outdoor running and don't know what they are missing or else they did outdoor but weren't very good at it. Occasionally people who regularly do outdoor will need to do treadmill (weekend byself, when feeling lonely etc) but it's rare and they know it's no substitute for the real thing. As those books that I read when I was younger said treadmill running is fine but not if it becomes a lonely obsession. To get real highs, it must be outdoor running. Outdoor > Treadmill.

robinph

...and the bright lights inside the gym probably make you go blind as well.

bart simpson

Aimman wrote: »

Nope, if he'd stationary relative to the ground, then he cant take off, because there is no air passing over and under the wing. The rapid passing of air around the wing causes lower air pressure above the wing then under it because of the curvature of the wing. The low pressure above the wing will pull the wing up and consequently pulls the plane with it, thus take off. The jet engines only make the plane go forward, the wings shape makes it take off.

What I'm interested in finding out, is what happened when the treadmill is up to that 200mile/hour speed, what happens to the plane when someone hits the emergency stop on the treadmill????

equilibrium speed plus normal take off speed makes it imposssible for plane to be stationary, therefore it will move, therefore air will pass over and under wing, therefore plane will be take off.

sideswipe

bart simpson wrote: »

equilibrium speed plus normal take off speed makes it imposssible for plane to be stationary, therefore it will move, therefore air will pass over and under wing, therefore plane will be take off.

Yes but you have to allow for the spin of the earth as well i.e if the treadmill is in the north-pole there will be negligible spin, if it's on the equator you would have to factor in 1038 mph approx (about 700mph in Ireland) I hope this clears the issue up a little.
On another point are we talking big treadmill or little plane?

bart simpson

sideswipe wrote: »

Yes but you have to allow for the spin of the earth as well i.e if the treadmill is in the north-pole there will be negligible spin, if it's on the equator you would have to factor in 1038 mph approx (about 700mph in Ireland) I hope this clears the issue up a little.
On another point are we talking big treadmill or little plane?

no you dont have to allow for the spin of the earth, as the athmoshere is spinning with the earth, the air around the plane will be stationary to the ground (excluding weather)

sideswipe