Archived posting to the Leica Users Group, 2001/05/15

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Subject: Re: [Leica] Laithewaite
From: Johnny Deadman <john@pinkheadedbug.com>
Date: Tue, 15 May 2001 06:25:56 -0400

on 5/15/01 3:14 AM, Robert Appleby Personal at rob@robertappleby.com wrote:


> I saw this demo myself on Tv around that time. However, what occured to me
> immediately and puzzled me about Laithewaite's approach, was that he didn't
> _weigh_ his rotor before and after spinning it up. He just did the look mum
> I can lift it trick.
> 
> If he had weighed it and it had weighed less, that would have been genuinely
> astounding. For some reason he never did. Just as he never proposed jumping
> out of a fourth storey window with spinning gyroscopes in each hand.

Well, I don't wish to become a Laithwaite-advocate BUT if you do a search,
according to newspaper reports of the original 1974 demonstration in front
of the Royal Institution he used a pair of kitchen scales to weigh the
apparatus, which apparently weighted 20 pounds stationary and 15 pounds
spinning.

> A fifty pound object stabilised by a gyroscope will be easier to lift
> because the lever effect is cancelled out by the  gyroscopic stabilisation -
> it feels as if you're always lifting it through its centre of gravity
> wherever you hold it. This makes it easier to lift, just as a small heavy
> object is easier to lift than a large object of the same mass.
> 
> Try carrying a ten kilo child snugged into your waist and ten one-litre
> bottles of water in a plastic pack by the handle and tell me which you'd
> rather do. Do small children exert an anti-gravity effect? (they do of
> course - their insistence that we carry them)

Wow, this is boring, but I did mechanics as part of my abortive math degree
and a gyroscope's center of mass is not affected by its spinning. What
happens is that the force you apply to the spindle is converted into
twisting motion. What you would have seen if what you are describing is the
case is the gyroscope device obviously twisting as it was raised in
Laithewaite's hands (maybe you did).

As far as I can work out the Jones/Laithwaite device used two
counter-rotating gyroscopes, which would have cancelled out any apparent
leverage effect.

I am just being a devil's advocate here.
> 
> I also saw the antigravity machine. Not a convincing demo. It jerked
> forwards and backwards and any net forward motion was evidently due to
> friction in the wheel bearings. There was also a jumping machine which used
> the same jerking motion to achieve its effect - a bit like TM levitators.
> 
> The overall impression I got from these demonstrations was that Laithewaite
> was, for reasons unknown, completely off his rocker. The objections to his
> methods and conclusions were too elementary.

Yes, and that's my problem with them. I've seen Laithewaite interviewed on
TV numerous times and he's certainly eccentric and probably 'off-his-rocker'
BUT he isn't a complete fool and he certainly understands dynamics. One
thing I learned very early on in my career in TV was that you couldn't
dismiss stories brought to you by complete loonies, as in fact almost ALL
stories, true or false, good or bad, were brought to you by loonies.
> 
> The fact that he then entered into a lengthy correspondence with my father
> about gyroscopes, the precession of the equinoxes and the circulation of
> blood in horses and man just confirmed this impression.

Yeah, well, um.


- -- 
John Brownlow

http://www.pinkheadedbug.com