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Seriously now, can it take off or not? What do you think?

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Aerodynamics Discuss the physics of flight revolving around the aerodynamics and design of aircraft.
View Poll Results: A poll
Yes, it will take off.
69.66%
No, it won't take off.
30.34%
Voters: 89. You may not vote on this poll

Seriously now, can it take off or not? What do you think?

Old 12-15-2005, 01:27 PM
  #326  
David Cutler
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Default RE: Seriously now, can it take off or not? What do you think?

Excellent comments, if I may say so! 100% agree!

-David C.
Old 12-15-2005, 01:31 PM
  #327  
rmh
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Default RE: Seriously now, can it take off or not? What do you think?

The amazing part of all this is that the "question" fails on logic -
No engineering is required -no formulas -nothing
Libby the dog saw thru it from day one -
-
Old 12-15-2005, 01:41 PM
  #328  
David Cutler
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Default RE: Seriously now, can it take off or not? What do you think?


ORIGINAL: dick Hanson

The amazing part of all this is that the "question" fails on logic -
No engineering is required -no formulas -nothing
Libby the dog saw thru it from day one -
-
Yep!

-David C.
Old 12-15-2005, 02:56 PM
  #329  
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Default RE: Seriously now, can it take off or not? What do you think?

Regarding flying lawyers......if you pay the lawyer to fly, the plane will fly. If you pay the lawyer to not fly, the plane won't fly, it's the nature of the profession, lol!
Old 12-15-2005, 05:37 PM
  #330  
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Default RE: Seriously now, can it take off or not? What do you think?

Hey Dukester, you are pretty good with math, maybe you could help me with a problem I have had for years.

A runner wants to run a certain distance - let us say 100 meters - in a finite time. But to reach the 100-meter mark, the runner must first reach the 50-meter mark, and to reach that, the runner must first run 25 meters. But to do that, he or she must first run 12.5 meters.

Since space is infinitely divisible, we can repeat these 'requirements' forever. Thus the runner has to reach an infinite number of 'midpoints' in a finite time. This is impossible, so the runner can never reach his goal. In general, anyone who wants to move from one point to another must meet these requirements, and so motion is impossible, and what we perceive as motion is merely an illusion.

Where did I go wrong?

Old 12-15-2005, 05:58 PM
  #331  
David Cutler
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Default RE: Seriously now, can it take off or not? What do you think?

Your problem lies in a very common area. It's the zero conundrum.

If you consider an infinite number of way points then it must only take an infinitely small time to get between them. That is, zero time.

So the total journey involves multiplying infinity by zero, which, conventionally, (but not actually!) equals 1, but can be proved to equal any number.

Calculus uses a similar convention.

-David C.
Old 12-15-2005, 06:26 PM
  #332  
js3
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Default RE: Seriously now, can it take off or not? What do you think?

Since space is infinitely divisible, we can repeat these 'requirements' forever.
Not necessarily. Some physicists believe that the smallest unit where no more division (other than imaginary) is possible is the Planck length--about 1.6 X 10 -35 meters. (If I new how to put this in superscript I would).
Old 12-15-2005, 10:12 PM
  #333  
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Default RE: Seriously now, can it take off or not? What do you think?

ORIGINAL: mr_matt
Hey Dukester, you are pretty good with math, maybe you could help me with a problem I have had for years.

A runner wants to run a certain distance - let us say 100 meters - in a finite time. But to reach the 100-meter mark, the runner must first reach the 50-meter mark, and to reach that, the runner must first run 25 meters. But to do that, he or she must first run 12.5 meters.

Since space is infinitely divisible, we can repeat these 'requirements' forever. Thus the runner has to reach an infinite number of 'midpoints' in a finite time. This is impossible, so the runner can never reach his goal. In general, anyone who wants to move from one point to another must meet these requirements, and so motion is impossible, and what we perceive as motion is merely an illusion.

Where did I go wrong?
My true math skills are pretty rusty, got to be some college age kids in here much better than me. What I lack for in young brains, though I make up for in practical applications.

This is the same type problem as the "if I'm ten feet from a wall and step half the distance to the wall each time, how many steps will it take until I reach the wall?". The theoretical answer of course is you will never reach the wall, but the practical answer is that very quickly the step length becomes smaller than your body's motor skills will allow with precision and you will indeed reach the wall simply by suffering from that affliction known as being human. Note that the more clumsy and teens who don't tie their shoes will reach the wall slightly faster that the rest of us.

In regards to your question, the same kind of thing applies from the practical aspect, if we assume the runner proceeds with constant velocity, then unless the observer can intentionally decrease their perception of the passage of time, the runner will not be observed to slow down and take an infinitely long time to reach the end. Instead, the observer will perceive the runner to reach the 50% marks at an progressively faster rate up until the upper range of their temporal perception. At that point, the runner will appear be stepping beyond the 50% mark in the minimum time unit the observer can perceive.

Duke

Edit:
One of the things I liked about the proof statement for the lack of a solution for the conveyor speed equals wheel speed argument above is the simplicity of the approach. For the equations I used:
Vc=Vw
Vw = Vp+Vc

In essence these are both equations for a line with one having an intercept of 0 and the other having an intercept of Vp. So if you were to say Vw=Y and Vc = X, you get

X=Y or flipped for Y=X for the standard format
and
Y=X+Vp

Since both lines have a slope of 1 but different intercepts, you could easily make the same proof graphically by plotting the lines. For all Vp<>0, they have no intersecting points (lines with the same slope being parallel and all), for Vp=0 they intersect at every point and there is no single unique solution.

[Ok major geometry nerdly meltown over with for the moment. ]


Old 12-16-2005, 02:50 PM
  #334  
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Default RE: Seriously now, can it take off or not? What do you think?


ORIGINAL: David Cutler

I'm sorry, I didn't understand any of that, mainly because it started with the statement:-

If the plane accelerates at 2mph
Which is a false premise as acceleration isn't measured in mph (that's a velocity or speed, not an acceleration).

Would you care to rewrite it?

-David C.

Sorry 0.00055555555555556mile/second^2
Old 12-22-2005, 02:38 PM
  #335  
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Default RE: Seriously now, can it take off or not? What do you think?

I am not sifting through all of this again, but I would like to have 1 reason it will fly in 2 sentances. You think prop wash is enough to fly the plane?
Old 12-22-2005, 03:08 PM
  #336  
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Default RE: Seriously now, can it take off or not? What do you think?

Is prop wash enough?
No.

-David C.
Old 12-22-2005, 03:10 PM
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Default RE: Seriously now, can it take off or not? What do you think?

DO you think it will fly on something otherwise?
Old 12-23-2005, 07:12 AM
  #338  
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Default RE: Seriously now, can it take off or not? What do you think?

Damn , I just answered this question in the other thread , so to find my calculations read the last page in the other thread, then have a Happy and Safe Christmas to everyone
Old 12-23-2005, 12:12 PM
  #339  
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Default RE: Seriously now, can it take off or not? What do you think?

Madgenius, did your calculations allow it to fly?
Old 12-23-2005, 04:49 PM
  #340  
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Default RE: Seriously now, can it take off or not? What do you think?

ORIGINAL: Dart373

I am not sifting through all of this again, but I would like to have 1 reason it will fly in 2 sentances. You think prop wash is enough to fly the plane?
1: Because wheels roll freely with little friction, the treadmill cannot restrain the airplane whichever way it moves.

2: If the airplane has enough thrust to takeoff from a regular runway, it can takeoff from the treadmill, no matter which way it moves.

Old 12-23-2005, 05:31 PM
  #341  
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Default RE: Seriously now, can it take off or not? What do you think?


ORIGINAL: Bax

1: Because wheels roll freely with little friction, the treadmill cannot restrain the airplane whichever way it moves.
The question states that the belt matches the speed of the wheels exactly. How can the wheels advance on the treadmill if this is so?
Old 12-23-2005, 11:25 PM
  #342  
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Default RE: Seriously now, can it take off or not? What do you think?

The belt controls the speed that the wheels spin , not the airplane. That is one of the misleading parts of the question. To some people the question appears to imply that the plane is held back by the conveyor belt somehow , but it simply does not state that. It does not say that the plane is prevented from moving foward in any way, manner or form. You are being tricked by the wording, read the question again, very carefully.
Old 12-24-2005, 12:12 AM
  #343  
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Default RE: Seriously now, can it take off or not? What do you think?

ORIGINAL: PowerPlay

The belt controls the speed that the wheels spin , not the airplane. That is one of the misleading parts of the question. To some people the question appears to imply that the plane is held back by the conveyor belt somehow , but it simply does not state that. It does not say that the plane is prevented from moving foward in any way, manner or form. You are being tricked by the wording, read the question again, very carefully.

Maybe it is just me but I am beginning to let this rediculous thread get to me....
We said Airplane, not powerhouse 3D plane with huge prop... So.per the original question
1-The Airplane( lets say a Cessna Caravan single engine scale plane for giggles) is on the belt.
2-You said the belt will always match the wheel speed....If this is the case, then you just said no matter what friction, the belt will always hold back the plane(belt speed is now 37,000 mph)
3-You never said anything about friction on the wheels... they will make friction. At some point in time, YOU WILL EXCEED THE SPEED of the plane with belt speed. ALthough maybe 2 million mph belt speed.. it can overpower the wheels, or at least match them as asked before.

I may regret this, but you guys who say it will 3D on the belt, sure it will fly, all that crud, need to reread the question! The belt will hold it back ! At least you said so yourself in the quiz.... you said the belt will match the damn plane speed/wheel speed.

If you said belt mph =Wheel mph, then thats one thing, make very different wheel size and then your belt speed/wheel speed is matched, but the mph of the plane is positive ground speed... ?

So for whoever asked this question, get in a 50 mph stall speed airplane and go into a 50 mph solid smooth tailwind and let me know how hard the trees are at the end of the runway.... Oh wait, if the runway was only a belt...:ee k:
Old 12-24-2005, 08:12 AM
  #344  
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Default RE: Seriously now, can it take off or not? What do you think?

Too funny how many people voted yes, it shows they cannot understand the simplest fundemantals of flight....

I voted no, grinned at the results

Yes, it will take off. 69% (51)

No, it won't take off. 30% (22)

Total Votes : 73

In a poll of 73 people, only 30% understood the question and how an airplane flies, it's Christmas Eve, 2005, and people still just don't understand even the basics, no wonder it took mankind so long to build the first airplane.......

I guess you should explain to people how an aerofoil works within that question, you would be educating the general public, good job on the question, it's enlightening coupling it with the poll

For the record, it cannot fly because there isn't enough lift, "even produced from the prop" in the traditional airplane since it's not displacing the proper volume of air around the wings, add some fans and/or wind and you are good to go if enough volume exists, "take note Navy air craft carriers, you can reproduce this suggestion in case you wanted to shorten the runways".

The air taking more time to travel over the top of the surface needs to meet up with the air traveling underneath the wing causing lift trying to even itself out. If you want a more direct visual, place an object in the water, especially a square one, you'll notice force from the eddy/wake it creates in certain areas, this force is what pushes the wing up. Thrust does help, but it's purpose is to get that "stream" of air to surround the wing out of proportion, causing a more fine tuned eddy and the reaction of it trying to balance itself naturally creates and upwards thrust motion.
Old 12-24-2005, 09:30 AM
  #345  
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Default RE: Seriously now, can it take off or not? What do you think?

You are not serious -of course --
Old 12-24-2005, 11:19 AM
  #346  
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Default RE: Seriously now, can it take off or not? What do you think?

and people still just don't understand even the basics, no wonder it took mankind so long to build the first airplane.......
Unlike somebody who calls themselves 'Espresso- Outfitters', you mean?



My advice - stick to outfitting quickly.

[sm=bananahead.gif]

-David C.

Old 12-24-2005, 09:54 PM
  #347  
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Default RE: Seriously now, can it take off or not? What do you think?


ORIGINAL: dick Hanson

You are not serious -of course --

Dick, to me or him were you replying?
Old 12-25-2005, 07:06 AM
  #348  
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Default RE: Seriously now, can it take off or not? What do you think?

I should not even have posted -
The "gag" question - wheels turning /not turning on a belt was a bit of a teaser -till you look at the the real question:
does the turning of the wheels have any relevance?
As long as the propulsion of the craft is NOT involved with turning of the wheels - (the two are not tied together -wheel turning is simply a method of reducing friction-a slipper skid will do it's same job) )the answer is NO
It is a bit of a nonsense thing in that only two scenarios exist :
the wheels turn in normal direction -or they don't turn at all
In either case
the craft simply accelerates at a normal pace

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