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MythBusters Airplane Takeoff Myth

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MythBusters Airplane Takeoff Myth

Old 03-18-2009, 07:49 AM
  #176  
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Default RE: MythBusters Airplane Takeoff Myth

Those heads are flying just thousandth's of an inch over the HD surfact. So it would have to be a really really small model. Quite literally a micro model.
Old 03-18-2009, 08:26 AM
  #177  
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Default RE: MythBusters Airplane Takeoff Myth

The heads on "full scale" storage devices have "floated on air" for years and years. The early drum devices were the first. On startup, they would spin up speed before the heads were released. Almost everything that moves fast enough has an attached boundary layer of air. When the drums were at speed, the heads were released and actually (not literally, actually) floated on the boundary layer. When the industry developed disc mass storage devices, the design worked there too.


BTW, that's been since the 50s-60s. Some of the drums were actually the size of barrels you'd have on your farm or factory. Some were smaller of course. The drum was on it's side in the cabinet. A gravity consideration of course.

The industry moved to discs with their platter shape to benefit from the more easily manufactured surface accuracy. And platters are easier to spin up to speed. Less mass.
Old 03-18-2009, 08:39 AM
  #178  
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Default RE: MythBusters Airplane Takeoff Myth

BTW, those drums had some interesting problems.

Head crashes were exactly that. Part of the head control hardware would grip the heads when needed. A power outage would remove that capability. And of course the drum would no longer be driven at speed. And it'd slow down. And the boundary layer would dissipate. And the heads would dig right into the still spinning phenolic. And PEEL AND PEEL AND PEEL.........

Also, sometimes a bearing would fail..... but that ain't related to aerodynamics, so no value in recounting the awesome consequences of that.
Old 03-18-2009, 05:28 PM
  #179  
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Default RE: MythBusters Airplane Takeoff Myth

A conveyor could keep a car in place. But not an airplane.
Old 03-18-2009, 06:22 PM
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Default RE: MythBusters Airplane Takeoff Myth


ORIGINAL: da Rock


The industry moved to discs with their platter shape to benefit from the more easily manufactured surface accuracy. And platters are easier to spin up to speed. Less mass.
My first computer related job was running an IMB system3 mainframe. The hard drive was the size of a large refrigerator and the disks were a stack the size of LP records that went down into a drawer in the machine. That was about 30 yrs ago! Anyone else remember OCL punch cards too?[X(]
Old 03-18-2009, 07:08 PM
  #181  
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Default RE: MythBusters Airplane Takeoff Myth

My first job was as a summer hire at Lockheed between school semesters. It was a real basic computer where all it did was read tapes brought over from the big IBM 360 in order to print out the IBM's output. Later as a real aero eng at McDonnell Douglas I used to have to punch my own cards for small input changes. The big punch jobs we wrote out on tablets and sent them for the KeyPunch Ladies to do. I am amazed that they could be as accurate as they were. Of course I hated to do the computer related stuff since I was a real aero engineer and wanted to design airplanes. Unfortunately for me our Six-Degree-of-Freedom program required inputs with the card stacks we would submit to the computer area. Sometimes it would be a full box of the type that the blank cards came in.

Today we just ask the computer to please analyze what I am thinking of and - poof - instant airplane. Well almost that good I think. I quit just before the time the first personal computer was put on a desk. Aero eng would be interesting today.

Ben


Old 03-18-2009, 07:30 PM
  #182  
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Default RE: MythBusters Airplane Takeoff Myth

Speaking of the Takeoff Myth, when I worked at Lockheed our windtunnel there (a low speed one (lower than mach)) did some outside work for some of the NASCAR teams. And there was discussion by the tunnel management of what it'd take to setup the tunnel to have a moving track that would make auto testing more realistic. Now there is the intelligent treadmill for sure. It would have to be timed to the airflow. Unfortunately for Mythbusters, they didn't know about that type of tunnel.

As far as I heard, that tunnel was not modified, but in dealing with some of the NASCAR teams around here, I know they have recently tested in moving "road" tunnels.

Wouldn't that be ironic. Mythbusters would want to use a windtunnel that had been modified from testing airplanes to testing automobiles by changes to better test cars, and the changes made the car test tunnels better suited to test airplane takeoffs. Man, that chain goes around in circles like these discussions of the myth.
Old 03-18-2009, 07:59 PM
  #183  
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Default RE: MythBusters Airplane Takeoff Myth


ORIGINAL: Tim Green
A conveyor could keep a car in place. But not an airplane.
Why would you use an airplane to keep a car in place anyway?


Old 03-18-2009, 08:25 PM
  #184  
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Default RE: MythBusters Airplane Takeoff Myth

I dreamed of an elephant in my pajamas
How the elephant got in my pajamas is a mystery.
Groucho Marx
Old 03-18-2009, 08:29 PM
  #185  
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Default RE: MythBusters Airplane Takeoff Myth

Dick, did you ever find a photo of your airplane that had the wide fuselage as compared to the height? And would you show us it?

Ben
Old 03-18-2009, 10:30 PM
  #186  
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Default RE: MythBusters Airplane Takeoff Myth

It's in a photo album (remember those?) - I will ltry to remember to photograph it and send it
easier than a scan . photo stays in album!
Old 03-19-2009, 09:43 AM
  #187  
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Default RE: MythBusters Airplane Takeoff Myth


ORIGINAL: dick Hanson

I dreamed of an elephant in my pajamas
How the elephant got in my pajamas is a mystery.
Groucho Marx
....and it had tusks that were very tight.
But in Alabama the Tuscaloosa.



Old 03-19-2009, 09:48 AM
  #188  
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Default RE: MythBusters Airplane Takeoff Myth


ORIGINAL: Ben Lanterman

My first job was as a summer hire at Lockheed between school semesters. It was a real basic computer where all it did was read tapes brought over from the big IBM 360 in order to print out the IBM's output. Later as a real aero eng at McDonnell Douglas I used to have to punch my own cards for small input changes. The big punch jobs we wrote out on tablets and sent them for the KeyPunch Ladies to do. I am amazed that they could be as accurate as they were. Of course I hated to do the computer related stuff since I was a real aero engineer and wanted to design airplanes. Unfortunately for me our Six-Degree-of-Freedom program required inputs with the card stacks we would submit to the computer area. Sometimes it would be a full box of the type that the blank cards came in.

Today we just ask the computer to please analyze what I am thinking of and - poof - instant airplane. Well almost that good I think. I quit just before the time the first personal computer was put on a desk. Aero eng would be interesting today.

Ben


I first learned IBM 360 Assembly Language in 1970. The computer lab had a "large" (768K core) Model 75 (I think). We all had to do our own keypunching when we wrote our programs. Write up the code on paper, then "type" it onto the cards. The semester term project was to write a program that simulated a machine the professor designed. Took an entire box of cards. You'd carry the cards back and forth to the lab as you submitted your program to be run. You'd get the results, debug it, re-type the code, and then return the box to run again. Sometimes, you'd have as much as a 7-day turnaround due to computer breakdowns, heavy student load, and so on.

Today, my laptop makes that "big" machine look like a toy. Today's stuff was science fiction, then.


Old 03-19-2009, 10:15 AM
  #189  
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Default RE: MythBusters Airplane Takeoff Myth

Today's stuff is STILL science fiction
That , blended with the most perverse programs imaginable.
I wrote a very simple program (in plain English) in 1976, to allow computerized flow of stocklists/building instructions for various models of machines our company built.
Computers were dumb tools then and simple instructions sufficed.
Or so I thought

What happened?
Old 03-19-2009, 11:03 AM
  #190  
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Default RE: MythBusters Airplane Takeoff Myth

Dick, I was looking around in the basement for something - since forgotten - yesterday and ran across a whole bookshelf of the old Byron originals flyin photos. Those were the good old days - I really enjoyed the afternoon shows. I must have spent a small fortune on film and developing.

I am eagerly awaiting the photo.....

Oh yeah, what I do find interesting is that the Star Trek writers missed the communicator size a whole lot :-)

Ben
Old 03-19-2009, 11:16 PM
  #191  
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Default RE: MythBusters Airplane Takeoff Myth


ORIGINAL: Tim Green
A conveyor could keep a car in place. But not an airplane.
Not all conveyors could keep all cars in place, but some conveyors could keep some airplanes in place.
Old 03-20-2009, 03:28 AM
  #192  
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Default RE: MythBusters Airplane Takeoff Myth

What if the belt actually started to move the air also above the belt as fast as the belt...then the width of the belt would be good to know too.
Old 03-20-2009, 02:28 PM
  #193  
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Default RE: MythBusters Airplane Takeoff Myth

I think the original intent of the question was such that you wouldn't have to get into the esoteric bits and pieces of things like the belt moving the air. But indeed if the airplane was small enough and the belt had enough roughness it could be flying in the boundary layer of moving air of the belt.

Ben
Old 03-20-2009, 03:05 PM
  #194  
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Default RE: MythBusters Airplane Takeoff Myth

But indeed if the airplane was small enough and the belt had enough roughness it could be flying in the boundary layer of moving air of the belt.
Maybe, if it were as small as the period or comma of this sentance.
Old 03-20-2009, 04:55 PM
  #195  
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Default RE: MythBusters Airplane Takeoff Myth


ORIGINAL: Shoe


ORIGINAL: Tim Green
A conveyor could keep a car in place. But not an airplane.
Not all conveyors could keep all cars in place, but some conveyors could keep some airplanes in place.
A conveyor is to a car, as a moving stream of air is to an airplane.
Old 03-20-2009, 09:56 PM
  #196  
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Default RE: MythBusters Airplane Takeoff Myth

Or why you can't jump if your shoes are nailed to the floor?
However, you CAN levitate by sitting in a chair, firmly grasping the underside of the seat (both hands!) and pulling upwards with all your might. That's what I heard anyway...
Old 09-15-2020, 06:23 AM
  #197  
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Default

hmm, first i was sure that it would not work, but i am not sure what to think about it

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