shrockworks xterraparts
XOC Decal
Newest Members
Glim, ChossWrangler, Patman, ChargedX, Randy Howerton
10084 Registered Users
Recent Posts
The NEXTerra April Fools @ AOAA!
by Tom
12/04/18 11:46 AM
Shout Box

Who's Online
0 registered (), 65 Guests and 1 Spider online.
Key: Admin, Global Mod, Mod
Page 7 of 43 < 1 2 ... 5 6 7 8 9 ... 42 43 >
Topic Options
Rate This Topic
#165862 - 29/12/06 06:08 AM Re: Know that if you do not post in this thread today the human race may cease to exist
TJ Offline
Member
*****

Registered: 08/03/01
Posts: 7756
Loc: Lawrenceville, NJ, USA
Quote:
Originally posted by Rockaholic:
[QUOTE]Easy

The square root of 1 = 1 and -1.
The square root of 1 = the square root of 1, so then 1 = -1
Not really, as having the same square root does not mean its the same number...as +/- 1 does not = 1.

And the "proof" above just says the same thing twice, and then draws the conclusion.

laugh

The square root of -1 is not 1, as 1 x 1 = 1, not -1.

laugh

That's where i comes in.

i = square root of -1
_________________________
- TJ

2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....

Friends don't let friends drive stock.

http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif

Top
#165863 - 29/12/06 06:19 AM Re: Know that if you do not post in this thread today the human race may cease to exist
RedX Offline

Member
*****

Registered: 25/04/01
Posts: 2394
Loc: Granite Falls, NC
Quote:
Originally posted by TJ:
OK, I just got back from the airport...I had my buddy build a giant conveyor belt down the runway, and we rigged it to match the plane's speed exactly (We're good).

laugh

Air Canada agreed to use it for one of their Tango Economy flights if we chipped in for some potato chips for the stew.

The plane fired up, and taxi'd onto the belt...let'r rip, and the thrust from the jets pushed the plane forward, down the runway belt.

The tires were turning at double the ground speed relative to the airport, as the belt whirred by beneath them.

It reached take off velocity, and took off...so we have our answer.

laugh

(Yay!)

OK - its settled!
The only part you left out was the pilot and co-pilot arguing about whether it would work or not.

Co-pilot was "We're just gonna sit there."

Pilot: "Naw.....we'll be fine.....Wheels are just gonna spin double-time. I saw on XOC that that would be what happens."

Co-pilot: "I don't think so."

Pilot: "Trust me......we're Canadian......What could go wrong? wink "

Guess that's why he's the pilot. laugh
_________________________
Brad & RedX

http://www.metzgardesign.com

Top
#165864 - 29/12/06 06:33 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


The Dyno analogy was with the rocket attached and the straps to the X removed prior to firing said rocket due to you couldn't get up to speed without the X being affixed to the Dyno in the first place. And I agree it would be very dangerous and stupid. Perfect for XOC. laugh

Top
#165865 - 29/12/06 06:46 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Rockaholic Offline
Member

Registered: 18/02/02
Posts: 1632
Loc: Reading, MA
Quote:
Originally posted by TJ:
And the "proof" above just says the same thing twice, and then draws the conclusion.

laugh

The square root of -1 is not 1, as 1 x 1 = 1, not -1.

laugh

That's where i comes in.

i = square root of -1
Yeah, well, I was just hoping no one would notice laugh
_________________________
Jeffrey
I'm just trying to put my tires on the rocks of life.

Top
#165866 - 29/12/06 07:18 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


The plane takes off.

100% positive. There is no doubt.

A plane's speed is NOT measured at the wheel. There is no speedometer hooked up the wheels. This is NOT an assumption; it's a fact. A plane's speed is measured by a tube that air passes through. In it's most basic form, wind comes into the tube, spins a little turbine, and the speed of that turbine is shown on the indicator on the dash. Now, there are other calculations that enter in, to compensate for the speed of the natural wind occuring at the time, but there's no reason to go into that for this problem.

In order for any movement to be recorded, air must come into the tube, which means the aircraft is in motion (again, not including the natural wind from the equation as it was not presented in the hypothetical problem).

The conveyor belt motion is directly proportional to the amount of speed the aircraft has at any given time. That's a given part of the problem.

The only way the conveyor belt moves is if the plane is moving. The only way the plane is "moving" is if its indicator says it's moving. The only way the indicator says it's moving is if wind is coming into the tube & turning the turbine. The only way wind enters the tube is if the aircraft is moving.

Therefore, the plane takes off, regardless of how fast the conveyor belt moves, because once the plane reaches 150+/- MPH, the wings literally get sucked up into the air, which lifts the body of the plane.

There are no "assumptions" necessary for the answer to this hypothetical problem.

Top
#165867 - 29/12/06 07:59 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


I think I may have been converted to the dark side. Maybe the plane takes off! lol.

I still think the conveyor could be configured to prevent the plane from going anywhere tho, there's gotta be some way to prevent the damn thing taking off. smile

Top
#165868 - 29/12/06 08:04 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by MattyX:
Quoting from someone on CO 4X4 site who's quoting avweb:
Quote:
It was an interesting argument, but as things progressed, more rational heads prevailed, pointing out that the airplanes do not apply their thrust via their wheels, so the conveyor belt is irrelevant to whether the airplane will takeoff. One guy even got one of those rubber band powered wood and plastic airplane that sell for about a buck, put it on the treadmill someone foolishly donated to the Lounge years ago, thinking that pilots might actually exercise. He wound up the rubber band, set the treadmill to be level, and at its highest speed. Then he simultaneously set the airplane on the treadmill and let the prop start to turn. It took off without moving the slightest bit backwards.
Did everybody forget that the scenario has been proven with a rubber-band plane?

...

EDIT: This is not rocket science, this is not aerospace engineering. This is a 9th grade physics problem and the correct answer is that the plane takes off.

....

Besides, that "Hu's on first" video I posted is hilarious. Y'all are missin' out! [Finger]

Top
#165869 - 29/12/06 08:34 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Mobycat Offline
Member
*****

Registered: 12/09/00
Posts: 8374
Loc: the hue of dungeons and the sc...
I just asked my boss (he's a marine engineer, though).

He thinks it will absolutely NOT take off.

The air is fluid - while it IS moving through the engines, it is NOT moving over the wings, meaning...no lift.
_________________________
"Nature has constituted utility to man the standard and test of virtue. Men living in different countries, under different circumstances, different habits and regimens, may have different utilities; the same act, therefore, may be useful and consequently virtuous in one country which is injurious and vicious in another differently circumstanced" - Thomas Jefferson, moral relativist

Top
#165870 - 29/12/06 09:05 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by Mobycat:
I just asked my boss (he's a marine engineer, though).

He thinks it will absolutely NOT take off.

The air is fluid - while it IS moving through the engines, it is NOT moving over the wings, meaning...no lift.
If air is moving through the engines, then it's providing thrust, which will provide forward movement of the aircraft because the wheels are FREE-SPINNING...

The problem didn't say the conveyor was moving at the same speed as the engines are rotating. It says it's moving at the same speed the aircraft will move. Again, the aircraft movement is measured by air going into a tube. If no physical movment of the aircraft, then no air going into tube, which means no movement of conveyor. If conveyor moves, then that means air is going into tube which means aircraft is physically moving (the conveyor movement is directly proportional to the aircraft physically moving), which means it will take off once it reaches the speed necessary.

Top
#165871 - 29/12/06 09:11 AM Re: Know that if you do not post in this thread today the human race may cease to exist
TK1 Offline
Member

Registered: 12/12/01
Posts: 671
Loc: Taylorsville, UT
Wow, I wonder how that plane stays in the air with the landing gear up? :rolleyes:
_________________________
Todd K.

Got paint?

Top
#165872 - 29/12/06 09:17 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Mobycat Offline
Member
*****

Registered: 12/09/00
Posts: 8374
Loc: the hue of dungeons and the sc...
But the *whole* plane has to have forward momentum to lift. It doesn't have that.
_________________________
"Nature has constituted utility to man the standard and test of virtue. Men living in different countries, under different circumstances, different habits and regimens, may have different utilities; the same act, therefore, may be useful and consequently virtuous in one country which is injurious and vicious in another differently circumstanced" - Thomas Jefferson, moral relativist

Top
#165873 - 29/12/06 09:18 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


An aircraft does not push against the surface to move, it pushes against air. Once the engines are turning, whatever the surface does is irrelevant. unless of course, it creates lateral friction instead of running longitudinally.

I name myself winner for being the first on this thread to get it right. Good thing I had to work at stupid o'clock yesterday. laugh

Top
#165874 - 29/12/06 09:59 AM Re: Know that if you do not post in this thread today the human race may cease to exist
XPLORx4 Offline
Member

Registered: 23/03/01
Posts: 1906
Loc: San Jose, CA
Based on Xorand's response, I believe it may be possible in the hypothetical scenario for the plane to not take off, so I am in agreement with NYMadman, but not because the engines don't actually move the aircraft further forward on the runway. Note: the hypothetical scenario is vague about the term "speed", and it does not provide any details about the physical environment. Most of us are filling in the blanks with what we perceive as "common knowledge" in order to arrive at our conclusion that the plane will take off.

Here's something that only Xorand hinted at (which would prevent the plane from taking off):

The conveyor is either moving at an infinite speed, if its speed-detection mechanism uses the plane's wheelspeed sensors, or it's moving opposite to the plane's groundspeed, if its mechanism is based on that. Now, we know that inifinity is a theoretical concept, and that wheel bearings and tires certainly cannot REALLY rotate at an infinite speed before self-destructing (which would then cause the conveyor to stop). So, without functional wheels, the plane can't overcome the friction of its broken landing gear sticking out beneath its belly, and it won't take off.

If the conveyor moves backwards at the same speed the plane moves forwards through space, then you would need to know the design limitations of the wheel bearings and tires to determine if they can spin at twice the take-off speed of the aircraft. If they can't handle it, again you have broken landing gear and the plane will likely careen out of control as it rolls down the runway at 180+mph. If the landing gear can handle those speeds, then the aircraft will indeed take off.
_________________________
4x4 in uppercase is $X$!!!
1997 R50: VG33E/RE4R01A/TX10/3.7/R200A/ARB/4.636/H233B/ARB/4.636/321150R15

Top
#165875 - 29/12/06 10:07 AM Re: Know that if you do not post in this thread today the human race may cease to exist
TJ Offline
Member
*****

Registered: 08/03/01
Posts: 7756
Loc: Lawrenceville, NJ, USA
Damn Marine Engineers...he's wrong of course.

He made the same mistake, that the thrust won't push the plane forward for some bizarre reason.

laugh

Here's another way to test it...

Walk on a tread mill, while holding an inflated ballon at the open end...point the balloon so that when you let go...it will fly the same direction you are facing, against the direction of the tread mill belt...

It will shoot forward, it will not hover over the belt.

laugh

If some how holding it down, right at the belt surface somehow changes things for you...let the balloon go again from there....it will STILL shoot forward.

The thrust from the air rushing out of the balloon will push it forward, even if the ground or a belt, etc...is going the wrong way below it.

I personally promise that it will work.

laugh

The farting sound from the balloon is a bonus.

Enjoy.
_________________________
- TJ

2001 Xterra '03 VG33, SE 5 spd, 305/70/16's, Revolvers, UBSkidderz, Doubled AAL's, 3"SL/2"BL, winch/bumpers, skids, sliders, OBA, Snorkel, pine stripes....

Friends don't let friends drive stock.

http://www.gifsoup.com/view/501230/tj-tackling-crawlers-ridge-o.gif

Top
#165876 - 29/12/06 10:08 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Revisit the initial problem statement:

Quote:
This conveyor has a control system that tracks the plane's
speed
Notice the control system tracks the plane's speed. Not the wheel's speed, but the plane.

Nobody gives a rat's arse about the wheel speed; only the Plane's speed. So any suggestion/description that's based on what the wheels are doing at the time is irrelevent. The Plane is moving (speed) in order for the conveyor belt to move.

Whether the plane has wheels, floats, skids, or freaking hovers over top of the conveyor is of no consequence to the solution to the problem question.

Top
#165877 - 29/12/06 10:13 AM Re: Know that if you do not post in this thread today the human race may cease to exist
TK1 Offline
Member

Registered: 12/12/01
Posts: 671
Loc: Taylorsville, UT
Quote:
Originally posted by Mobycat:
But the *whole* plane has to have forward momentum to lift. It doesn't have that.
Yes it does, the conveyor has no effect on the air which provides the resitance to the thrust which propels the plane forward independant of what the wheels are doing with the exception of the brakes being applied. The plane doesn't care about the how fast the wheels are spinning, the wheels will just spin happily along (as the plane moves forward on or past the conveyor) until the plane takes off and then they will get tucked into their cosy little compartments until it's time to land.
_________________________
Todd K.

Got paint?

Top
#165878 - 29/12/06 10:13 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by Hawk:
How about this.....lets see if this can get to the ALR:

A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).

Will the plane be able to take off?
The conveyor is not turning at infinite speed. It is only matching the speed of the aircraft. Hence the conveyor's speed is limited by the aircraft's speed. If the aircraft is not moving, neither is the conveyor. If the aircraft is moving, it's using the air to do so, so no matter how fast the conveyor turns the plane will continue to move relative to a fixed point.

I can't think of any aircraft that have "wheelspeed sensors". Aircraft speed is measured in KIAS, Knots Indicated Air Speed (or mach, but not in this scenario). As air flows into a tube (the pitot tube) it spins a little pinwheel.

If the conveyor spins at triple or quadruple the plane's airspeed or groundspeed, it makes no difference.

Top
#165879 - 29/12/06 10:13 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by TJ:
Damn Marine Engineers...he's wrong of course.

He made the same mistake, that the thrust won't push the plane forward for some bizarre reason.

laugh

Here's another way to test it...

Walk on a tread mill, while holding an inflated ballon at the open end...point the balloon so that when you let go...it will fly the same direction you are facing, against the direction of the tread mill belt...

It will shoot forward, it will not hover over the belt.

laugh

If some how holding it down, right at the belt surface somehow changes things for you...let the balloon go again from there....it will STILL shoot forward.

The thrust from the air rushing out of the balloon will push it forward, even if the ground or a belt, etc...is going the wrong way below it.

I personally promise that it will work.

laugh

The farting sound from the balloon is a bonus.

Enjoy.
But remember, you have to test the ballon, first, to find out how fast it'll fly all on its lonesome, so you can make sure you setup the treadmill to match the speed... And it's no excuse if you can't run that fast; that's just the "bearings of the wheels" breaking...

laugh

(BTW: Even if you're a freaking Jamaican world class sprinter, the balloon is still gonna' leave your arse from the treadmill...)

Top
#165880 - 29/12/06 10:14 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by TJ:
Damn Marine Engineers...he's wrong of course.

He made the same mistake, that the thrust won't push the plane forward for some bizarre reason.

laugh

Here's another way to test it...

Walk on a tread mill, while holding an inflated ballon at the open end...point the balloon so that when you let go...it will fly the same direction you are facing, against the direction of the tread mill belt...

It will shoot forward, it will not hover over the belt.

laugh

If some how holding it down, right at the belt surface somehow changes things for you...let the balloon go again from there....it will STILL shoot forward.

The thrust from the air rushing out of the balloon will push it forward, even if the ground or a belt, etc...is going the wrong way below it.

I personally promise that it will work.

laugh

The farting sound from the balloon is a bonus.

Enjoy.
BUT - a heavy ass planes weight is sitting on the treadmill / runway thingy. If I stood on top of the plane and did the same thing with the balloon it would shoot forward, because the balloon isn't sitting on a set of wheels etc, which need to rotate for it to gain speed to get airborn.

The wheels may not have any power going to them, but they still have to spin for the plane to move forwards along the runway. If the treadmill is totally cancelling out the forward motion of the wheels then the plane ain't going anywhere.

I'm torn, I thought I agreed with you guys now that the plane would take off, but my brain just says no it won't! lol.

Top
#165881 - 29/12/06 10:14 AM Re: Know that if you do not post in this thread today the human race may cease to exist
jorge Offline
Member

Registered: 27/11/00
Posts: 1147
Loc: Montclair, NJ
Quote:
A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed
and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction).
Not wheel speed.

There is no reason why the plane won't fly.

Think of this, if the plane is just sitting there, someone straps a rope to the plane. From off the belt they pull on it for 10 feet.

Now the plane will move 10 feet. The belt would have moved backwards 10 feet, and the wheels turned a total of 20 feet.
_________________________
-Jorge (pronounced hor-hey)

Plethora of photos , videos , a Phlog ,
and a site with kittens .
Sign up for the Nor\'Easter
www.njax.net
NJAX.net profile
--------------------
Homer, I see your daughter is one of those wave-kissing, Dukakis-hugging moon maidens.

Top
#165882 - 29/12/06 10:18 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by RiNkY:

The wheels may not have any power going to them, but they still have to spin for the plane to move forwards along the runway. If the treadmill is totally cancelling out the forward motion of the wheels then the plane ain't going anywhere.

I'm torn, I thought I agreed with you guys now that the plane would take off, but my brain just says no it won't! lol.
Dammit Rinky! Quit getting hung up on the wheels... The wheels have nothing to do with it; they FREE-SPIN, regardless of how fast the plane moves or how fast the conveyor moves.

Top
#165883 - 29/12/06 10:22 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


Quote:
Originally posted by RiNkY:
Quote:
Originally posted by TJ:
[b]Damn Marine Engineers...he's wrong of course.

He made the same mistake, that the thrust won't push the plane forward for some bizarre reason.

laugh

Here's another way to test it...

Walk on a tread mill, while holding an inflated ballon at the open end...point the balloon so that when you let go...it will fly the same direction you are facing, against the direction of the tread mill belt...

It will shoot forward, it will not hover over the belt.

laugh

If some how holding it down, right at the belt surface somehow changes things for you...let the balloon go again from there....it will STILL shoot forward.

The thrust from the air rushing out of the balloon will push it forward, even if the ground or a belt, etc...is going the wrong way below it.

I personally promise that it will work.

laugh

The farting sound from the balloon is a bonus.

Enjoy.
BUT - a heavy ass planes weight is sitting on the treadmill / runway thingy. If I stood on top of the plane and did the same thing with the balloon it would shoot forward, because the balloon isn't sitting on a set of wheels etc, which need to rotate for it to gain speed to get airborn.

The wheels may not have any power going to them, but they still have to spin for the plane to move forwards along the runway. If the treadmill is totally cancelling out the forward motion of the wheels then the plane ain't going anywhere.

I'm torn, I thought I agreed with you guys now that the plane would take off, but my brain just says no it won't! lol.[/b]
The wheels are providing NO forward motion. The forward motion is provided by the prop/turbine blowing enough air to push the plane along. The wheels do not *have* to spin, they just do. If you greased the whole conveyor with vaseline you could conceiveably do a wheels-up takeoff, but with considerably more friction (and hence, more need for power until the friction is overcome or until lift is achieved).

Top
#165884 - 29/12/06 10:22 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


I hope this doesn't get to almost 500 pages like this forum on the same subject: http://forum.physorg.com/index.php?s=314...05&#entry157036

How can I not hang around on the wheels, the plane before it gains any lift from the air has to make it to 150mph or whatever speed we feel is acceptable for lift off. Which means the wheels have to get the plane to that air speed before we have lift off. If the conveyor is reversing as fast as the plane is thrusting forward, I'm still 51% convinced that it ain't going anywhere! lol.

Top
#165885 - 29/12/06 10:25 AM Re: Know that if you do not post in this thread today the human race may cease to exist
Anonymous
Unregistered


The wheels don't get the plane anywhere, at any speed, ever. They just reduce friction with the ground.

Top
#165886 - 29/12/06 10:42 AM Re: Know that if you do not post in this thread today the human race may cease to exist
XPLORx4 Offline
Member

Registered: 23/03/01
Posts: 1906
Loc: San Jose, CA
RiNkY-

Stop thinking about the wheels. Imagine you're on a skateboard in an airport, and you're standing 20 feet from the end of one of those people-mover conveyor belts (on the side where people step off, not where you get on), but there's no people on it. Imagine that you have a jetpack attached to your back and that somehow you're able to control the jetpack so you don't kill yourself.

How do you start moving? You fire up the jetpack, right? How did you start moving? The jetpack pushed against the air.

OK, now you're moving forward because the jetpack is pushing the air, and you now jump onto the conveyor (which is moving backwards). Your roller skate wheels suddenly start spinning faster. What happens to the air that the jetpack is pushing against? Did it suddenly become very windy? No? Then you continue to move along the conveyor, although opposite to its direction of travel.
_________________________
4x4 in uppercase is $X$!!!
1997 R50: VG33E/RE4R01A/TX10/3.7/R200A/ARB/4.636/H233B/ARB/4.636/321150R15

Top
Page 7 of 43 < 1 2 ... 5 6 7 8 9 ... 42 43 >


Moderator:  RedX, RiNkY 

shrockworks xterraparts
XOC Decal