That totally blows away my MSpaint pictures. I <3 who ever made that.
[Devil’s handicap advocate]BUT WHAT IF IT WAS A SEA PLANE? THEN IT COULDN’T ROLLOL! AND HENCE COULD NOT TAKE OFF[/Devil’s handicap advocate]
As Joe said, I tried it. Not because I didn’t know what would happen, but in the hope that a real world demo would help car people get their “car sitting on a dyno wheel” mind past the fact that planes do not get thrust from their wheels.
Unfortunately I can’t seem to find the pictures I took and it looks like I deleted them from my web account. I found the file name from the old web image link, mythbust_at_home.jpg, but that file isn’t anywhere on my network at home. Unless I uploaded it from work I think it’s gone. But, long story short, a rolling treadmill and the slight friction from plane wheels simply can’t overcome the thrust of the prop. Yes, the wheel is spinning faster than normal, but the plane will still accellerate.
More like devil’s very retarded step cousin… :lol:
A sea plane, with floats and no wheels, wouldn’t even take off on a stationary runway.
.
that is all.
EDIT
I read why this was opened again
and i say what i still said on page one.
therefore I agree with wetwork
::LALALALALALALALALALALALA::
I still want to post up a simulation I’ll create when I get home. 
it has already ben covered that not all engineeirs can give a proper answer on if the plane would take off or not
think of it this way, the conveyor belt simply doubles the drag from the wheels / tires/ bearings … so therefor if i take a censa, put 6 wheels on it instead of 3, and try to take off on a normal runway, your sayingthe plane wonttake off ???
bullshit …
and you know what, planes can still fly while they are dragging a parachute, just like how a top fuel dragster can still drive down the track with the chute open , and parachutes create way more drag then wheels and tires
refere to previous drawing:
http://www.nyspeed.com/forums/attachment.php?attachmentid=542
you guys aremissing the point. yes if lift could be created by standing still then yes the plane would take off.
no matter hw you match the opposite direction of the treadmill to match the forward momentum of the plane
ie. 10 forward and the treadmill 10 back…
its like your running in place. which means your not going anywhere.
try this… run on your treadmill and you see that the speed that it travels backwards you have to meet which means you must speed up. if you don’t you fall off the treadmill going backwards. when you speed up your matching the treadmills speed.
when you match that speed you are again running in place.
a plane needs air flow to move above and beneath the wings to create lift the propulsion system is designed to move it in a forward motion so its gets enough speed to get the air above and below it to create the lift.
alot of you say it has to do with the jet engine producing so and so amount of thrust well the the truth is set the jet engine on a tarmac turn it on and see if it flys. i bet it won’t
all the parts on the plane work together to create the lift need or else we’d be doing it your way and implementing the treadmill running the oposite direction
by all means if you think im wrong. then i will go back to school and return my aerospace degree and you should then come to work where i do then tell your ideas to the boss who appens to have a a 6 year degree in it.
i could be wrong… but i know your idea will not work. so hate and bash on me all you want. just cause i work for boeing does not mean im bragging about it… saw someone mention it so i threw inmy ideas based off of the company i work for and the ideas that we have tried to save time and money to make air travel less costly and more efficient… so please if you want my job and think im so wrong and you can do it better then by all means.
so lastly i will close with this
a plane will not have the force need to create lift by standing still no matter how fast the the turbines are going. if your matching speed with speed the opposite direction no lift is being created and you would be running in place not going anywhere…
hotrodkid. i do not know if your agreeing or disagreeing here but i see your point. but the resistance need by standing in place is simply not there. hence we stick to the way its been done from day one. with the plane on the ground and not a treadmill.
the wheels can spin as fast as they want… the plane is not going forward. its at a stand still going very fast as the treadmill goes the opposite way
the point is that the example says the conveyor belt spins fast enough backwards as fast as the wheels are spinning forward
say you hop in your cesna, and taxi down the runway at 10 miles per hour
the conveyor will hence move the runway 5mph … and this will require slightly more throttle to maintain 5mph taxi speed
now you decide to take off, so you head back to the proper end of the runway, and you peg the throttle and start to build speed
you start to roll forward at 5mph in relation to the trees next to the runway, runway is doing 5mph in reverse, so the wheels themselves are doing 10mph
you gain some more speed, 20mph compared to the trees, wheels are seeing 40
50 compared to teh trees
100 compared to the trees … plane takes off
the only way to keep the plane on the ground is if you word the question like this
“a plane is sitting on a runway set up as a converyor belt, the runway will always move fast enough in reverse to not let the plane roll forward (beacuse of the friction of the tires and bearings) no matter how much thrust the engine produces”
but the only way to keep the plane on the ground in the example we ARE talking about, is if the plane is so under powered that the SLIGHT bit of extra friction from the wheels is all it takes to slow the plane down enough to kep the plane from generating sufficient lift to take off
AHHHHHH IT IS NOT STANDING STILL!!! THE WHEELS ARE NOT WHAT CAUSE IT TO MOVE FORWARD! THE JETS CAUSE IT TO MOVE FORWARD REGARDLESS OF THE FORCES ON THE WHEELS!!! GO BACK TO SCHOOL!
i understnd your point about the wheels. but the wheel speed is not relevent here
the jet engine will produce the thrust to move it forward. if your negating that by haveing the runway go the oposite direction the plane is not going forward.
you need to compare to calculate the thrust force in to miles an hour if you can figure that out.
once you do that you must determine the speed that the air needs to travel under the wing and thru the openings to create it to lift by sending the runway the opposite direction to meet the thrust in miles perhour you are simply negating air movement
yoiu would henceforth being not moving anywhere does that help more?
you would need to do 2 times the speed of the runway moving backwards to create lift. your first time speed is to match the conveyor belt moving against you, Your second time is the plane then moving out of the stand still and going forward like i towuld on a normal runway thus creating the speed and the force of air traveling thru it needed to create lift
you simply cannot create lift by going the same speed as the treadmill the opposite direction you need to move with it, by doing so you are creating 2 times the movemnet speed hence hurrying the air flow to go faster providing lift fast
then should i just quit and go back to school and tell them that someone on a car forum told me i was wrong and that my time wasted in school was not worth the money spent? because that car forum person drew up a diagram not factoring in that you need air moving to create lift?
yes the jets cause it to move forward but without the wheels that is just not possible and making the wheels do 2 times the mount of work makes the jets do 2 times the work making it no efficient.
yes it could work if you made the jets do 2 times or more the work then needed
Last time I post these, a few hours from now I’ll post a video…
if you move with a treadmill going the same direction going 100 miles an hour your jet system does not need to do as much work to propel the plane forward to create lift. your already going 1/2 if not 3/4 the speed you need to create lift.
when you thrust firward you are increasing your mass thats already going 100 an hour
plus your gonna go whatever milkes an hour you thrust forward so say you match the speed of the treadmill going 100 your not going 200 miles and hour thus creating lift before you even reach your end of the 100 miles per hour part.
how does making the treadmill go in reverse help this?
so my point i guess is this.
if your plane is sitting on a rnway thats moving forward at 100 miles and hour and your just sitting there, your already moving at a rate of speed of 100 miles an hour. your wheels are not moving. like i said your already going 1/2 to 3/4 of the speed needed without even propeling forward and moving your wheels.
when you engage the throttle thruster forward then you move the wheels which means your plane starts to catch up really quick to the speed your already going and you double it.
fuzzy fish is catching on to my idea… the plane is not getting the force of air it needs to lift it.
its simply being match to create and overworked jet engine and nothing but standing still to show for it.
which is why you need to move with it instead of against it.
when you run on a treadmill like i said and you go 5 miles and hour an hats how fast the treadmill is going your running inplace… well the plane is standing still with the wheels moving but its not going forward…
if you increase the jet engine to do 2 times the work then you will move forward
same as if your treadmill s going 5 against you and you start to increaseyour speed or double your effort your moving 10 and your moving faster then your treadmil hence your going forward and not standing the same spot.
Wtf, did you even read what I posted. Or look at the pictures for that matter. :bloated:
I stated the plane does take off and the bearings of the wheels don’t transfer enough kinetic energy from the conveyor belt to the plane it self to prevent it from taking off.
yes it is!
normal day: plane rolls down the run way @ 5mph, whels turn at 5mph
for the original question that caused this debate it states when the plane is moving forward, the runway goes teh same speed the other direction
so if the plane is rolling 100mph that way -------->
the runways is doing 100mph this way <-------
and a speedo attached to the wheel would indicate 200mph total
the origal question states nothing about using the runway to negate the engine thrust
again, this question can simply be demonstrated by askin if using 6 wheels instead of 3 wheels on the cesna would keep it from ever taking off
or refer to my image i linked to above, its shows EXACTLY what the question states, because the plane is tied to the runway with a pulley and a rope
therefore for every 10mph worth of forward speed the plane gets, the runway goes 10mph the other direction
ahh as you are correct i did misread you… i thought you were agreeing with me i apologize sir
Anyways I get home in an hour I’ll make a simulation of this scenario and that will show how it works with a nifty video. Plus gives me something fun to do tonight.
the wheels maybe doing 200 miles an hour but how are you creating the lift?
the way it looks is that you are going nowhere. the wheels are not a freestadning thing from the plane like you might think.
say your tread mill going this way
<--------- 100 miles per hour. with out any thrust applied its like your in N on a car and your wheels are going 100 miles an hour withthe treadmill
<------------- that way
now when you add 100 miles an hour of thrust you are then making your wheels run even with the tread mill going
----------------> that way going oposite directions meaning you are only doing 100 miles an hour the other way instead of being in nuetrel and your wheels going with the treadmill
so your wheels are going 100 miles an hour in the opposite direction when you do not add thrust.
when you add that 100 miles an hour of thrust you are now changing the drection the wheels are going. they are going to oppose the treadmill and go 100 miles an hour the opposite direction thus creating a no movement effect
so how are you getting lift?