I Have a Question :-)

rmciottijr

rmciottijr

Line Up and Wait
Joined
Apr 13, 2005
Messages
643
Location
Havertown
Display Name
Display name:
rmciottijr
What will happen.

Here's the original problem essentially as it was posed to us: "A plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction). Can the plane take off?"

Maybe it's the lack of sleep but I thought I might make some people laugh.:D
 
Oh Boy! Here we go again! Let me go get some popcorn and program the refresh button on my internet browser, so I can watch the debate. :D

Bob,.. I'm going by the jobsite tomorrow at 6:45am,.. want me to bring coffee and donuts over ?:) BTW, your website gets' stuck when I try to open it.
 
dmccormack said:
How is this -- far, far too easy problem -- even debatable??
Click to expand...

1. Somebody always seems to find this question and recirculate it - kinda like the Good Times virus email.

2. Some folks just don't understand the answer - and some of them even fly airplanes as PIC.
 
tell me, are we talking ground speed, IAS, or TAS
 
Not this one again!!!
BangHead.gif
 
Is it a laden or unladed treadmill?
 
Does the treadmill grade make a difference? You know, that whole angle of attack thing. :goofy:
 
kevin47881 said:
Does the treadmill grade make a difference? You know, that whole angle of attack thing. :goofy:
Click to expand...

Treadmills are graded as serviceable or unserviceable. What does that have to with the angle from which you chose to attack this thread?
 
.... I know what to do to get this moved so I don't have to look at it anymore........



... Is George Bush in charge of the treadmill? If so, will Obama keep the treadmill running after January?


Countdown to Spin Zone.... 3..... 2..... 1.....

:rofl::rofl::rofl:
 
kevin47881 said:
Does the treadmill grade make a difference? You know, that whole angle of attack thing. :goofy:
Click to expand...

*Drift* You know what amazes me? The angle of attack DOES make a difference on the treadmills in gyms. If you increase the resistance, it tilts "uphill." :dunno:

Is that a stupid feature as it really does add resistance as it tilts otherwise or is "walking" uphill really all it takes to add to your workload?
 
mikea said:
*Drift* You know what amazes me? The angle of attack DOES make a difference on the treadmills in gyms. If you increase the resistance, it tilts "uphill." :dunno:

Is that a stupid feature as it really does add resistance as it tilts otherwise or is "walking" uphill really all it takes to add to your workload?
Click to expand...

But wait with a high enough angle of attack the plane could not fly the wing would be stalled. Right:dunno::D

:blueplane:
 
RMCN172RG said:
But wait with a high enough angle of attack the plane could not fly the wing would be stalled. Right:dunno::D

:blueplane:
Click to expand...

Wouldn't that depend on the angle of the relative wind? :rofl:
 
mikea said:
*Drift* You know what amazes me? The angle of attack DOES make a difference on the treadmills in gyms. If you increase the resistance, it tilts "uphill." :dunno:

Is that a stupid feature as it really does add resistance as it tilts otherwise or is "walking" uphill really all it takes to add to your workload?
Click to expand...

Walking uphill really is all it takes to increase your workload. This is the only practical way to increase the energy it takes for you to walk--short of putting glue on your shoes.

Increasing the 'resistance' of the belt's movement would only accomplish one thing: make the electric motor work harder. You don't turn the belt on an electric treadmill--it turns itself--you just walk on it like a monkey. Don't believe me, quit walking and tell me what happens :)

Now if it was a manual treadmill, where you made the belt turn with your feet, increasing the resistance of the belts movement would put more work on you.
 
RMCN172RG said:
But wait with a high enough angle of attack the plane could not fly the wing would be stalled. Right:dunno::D

:blueplane:
Click to expand...

unless there was more thrust than the plane weighted, then it could, and fly vertical to gain altitude, then dive to get flying:dunno:
 
RMCN172RG said:
But wait with a high enough angle of attack the plane could not fly the wing would be stalled. Right:dunno::D

:blueplane:
Click to expand...

If you pointed the belt straight up, the angle of attack would not be any different then the airplane sitting level. Once the airplane moved forward, it doesn't matter if thats up, across , whatever, the relative wind will be coming from that forward direction.

Basically the wing wouldn't know the difference. It doesn't care which way its pointed. That said--you'd need enough thrust to overcome gravity. So it's really a thrust problem, not an angle-of-attack wing problem

AdamB said:
Wouldn't that depend on the angle of the relative wind? :rofl:
Click to expand...
As soon as the wing moved forward (even if that was straight up) the relative wind would be from that forward direction and would have a similar angle of attack as if it were moving forward over the ground.

You just need the thrust to overcome the weight (gravity) and the air resistance (drag) in this case.

rubber314chicken said:
unless there was more thrust than the plane weighted, then it could, and fly vertical to gain altitude, then dive to get flying:dunno:
Click to expand...

Exactly. If you had enough thrust to overcome the weight and the air reistance you could fly. I'm not sure why you would need to dive to get flying? You're flying in my book as soon as the thrust pushes you up. The wing will develop lift--it'll just be in the horizontal direction.
 
smigaldi said:
What if I use a low wing aircraft?
Click to expand...

Then it's most likely that you'll have to step on the wing to board the aircraft. Step only on the no-skid, thankyewverimuch.
 
jesse said:
Exactly. If you had enough thrust to overcome the weight and the air reistance you could fly. I'm not sure why you would need to dive to get flying? You're flying in my book as soon as the thrust pushes you up. The wing will develop lift--it'll just be in the horizontal direction.
Click to expand...

I'm no pilot (yet) but I guessed on that because if you were going straight up then the wing would have any lift and you'd need to gain some lateral speed, or forward air movement over the wing to get lift, and that could come from a dive, right? or would the elevators be effective in a vertical climb like that?
 
rubber314chicken said:
I'm no pilot (yet) but I guessed on that because if you were going straight up then the wing would have any lift and you'd need to gain some lateral speed, or forward air movement over the wing to get lift, and that could come from a dive, right? or would the elevators be effective in a vertical climb like that?
Click to expand...

It depends on your point of reference which I believe you are confusing here. Most primary texts will define lift as a straight up force, 180* from the gravity vector. If this is your thinking, then a wing on a plane traveling straight up is developing no lift.

But if your reference is the plane, not the world, all you need for the wing to be developing a force we call lift, is air moving over it. So the plane going straight up (and I am assuming that the pointy end is also straight up) will develop a force perpendicular (more or less) to the direction of travel, which would indeed move the plane off the vertical path it was on.

So the wing has airflow and is developing lift. All you need to do is change the direction of travel to horizontal without losing airspeed and you are flying straight and level. No need to dive to develop airspeed... you've got it!

-Skip
 
If you remove the non-skid, the plane will have less drag and be more likely to take off on a treadmill. But, still no guarantees!





:D
 
rmciottijr said:
What will happen.

Here's the original problem essentially as it was posed to us: "A plane is standing on a runway that can move (some sort of band conveyor). The plane moves in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the plane speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction). Can the plane take off?"

Maybe it's the lack of sleep but I thought I might make some people laugh.:D
Click to expand...

:vomit:

Bob, you are now officially on the list of people that need to be thrown in the river at Gaston's. :p

However, since you've never been to Gaston's, we'll have to find a body of water near Wings Field so that we can have a dunking ceremony at the FlyBQ. Or maybe we'll just solve two problems at once - You can be the pig next year. :rofl:
 
jesse said:
Walking uphill really is all it takes to increase your workload. This is the only practical way to increase the energy it takes for you to walk--short of putting glue on your shoes.

Increasing the 'resistance' of the belt's movement would only accomplish one thing: make the electric motor work harder. You don't turn the belt on an electric treadmill--it turns itself--you just walk on it like a monkey. Don't believe me, quit walking and tell me what happens :)

Now if it was a manual treadmill, where you made the belt turn with your feet, increasing the resistance of the belts movement would put more work on you.
Click to expand...
Hokay, I didn't have the model in my mind that you're constantly walking uphill on the belt to maintain your relative position vertically. The belt is pushing you back downhill.

....Here we go again. :D
 
rubber314chicken said:
I'm no pilot (yet) but I guessed on that because if you were going straight up then the wing would have any lift and you'd need to gain some lateral speed, or forward air movement over the wing to get lift, and that could come from a dive, right? or would the elevators be effective in a vertical climb like that?
Click to expand...

It has been done. See the following links:

http://en.wikipedia.org/wiki/Convair_XFY-1
http://en.wikipedia.org/wiki/Lockheed_XFV
http://en.wikipedia.org/wiki/X-13_Vertijet

The wing will produce lift once angle-of-attack and airpeed parameters are met.
 
You must log in or register to reply here.
Back
Top