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Author Topic: weight  (Read 5690 times)

Ow Abreast

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weight
« on: December 29, 2008, 11:43:23 AM »

what would the scale weight be at 1:10 for one ton
thanks for any help
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Sandy Calder

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Re: weight
« Reply #1 on: December 29, 2008, 12:12:40 PM »

length,width,height ar all divided by 10
so 1/10th scale weight of 1 ton is 1x(0.1)3
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bogstandard

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Re: weight
« Reply #2 on: December 29, 2008, 01:25:32 PM »

Imperial ton (2240lbs (pounds)) divided by 10 = 224lbs

Metric Tonne (1000kg (kilos) (2205 approx. lbs))  divided by 10 = 100kg (220.5lbs)


Not nit picking, just hoping it is slightly clearer.

John
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dougal99

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Re: weight
« Reply #3 on: December 29, 2008, 02:16:04 PM »

Imperial ton (2240lbs (pounds)) divided by 10 = 224lbs

Metric Tonne (1000kg (kilos) (2205 approx. lbs))  divided by 10 = 100kg (220.5lbs)


Not nit picking, just hoping it is slightly clearer.

John

Sorry to correct you but Sandy is correct the weight would reduce by the scale cubed so one ton (2240 lbs) at 1/10 would reduce by 10 cubed or 1000 so the scale weight would be 2.24 pounds and a metric tonne 2.205 pounds.

If this confuses you, just think about a pile of bricks. One brick would weigh one unit if you doubled the size that would be 2x2x2 bricks or 2 cubed which is eight bricks. Making it 3 times the size would result in 3x3x3 (3 cubed) bricks or 27 bricks. And so on!

Hope this makes it clearer

Cheers

Doug
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Bunkerbarge

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Re: weight
« Reply #4 on: December 29, 2008, 02:42:19 PM »

Doug is actually spot on, it's the old L-A-V ratio's from school maths. (Length, Area, Volume)

If you double a length you increase it by a factor of two so a 1" x 1" square would become 2" x 2" or 4 square inches.  Likewise a cube of 1" x 1" x 1" would become 2" x 2" x 2" or 8 cubic inches. 

This is obviously only volumetric ratio's so you would have to take into consideration density of the material in question to get the correct mass ratio but for a lot of modelling purposes volumetric ratio's would be close enough.

So as a guide your 1 Ton would equate to 1/1000th Ton on a 1/10th scale model.  Easier to think of in metric ( as usual!) 1kg would equal 1g on a 1/10th scale model or 1 Metric Ton would be 1 Kg, in both cases 1/1000th of the mass.
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bogstandard

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Re: weight
« Reply #5 on: December 29, 2008, 04:06:55 PM »

That was quick lads, soon had that cleared up.

I stand well and truly corrected, but surely my method of explanation, even though wrong, was a lot easier to understand than what was already shown, where it was assumed someone would have a good mathematical background.

Corrected it should read

Quote
To obtain 1/10th scale, divide by 10x10x10 (10 to the power of 3) = 1000

Another eg. 1/6th scale would be, 6x6x6 (6 to the power of 3) = 216. So you would divide the main figure by 216.

So 1/10th scale of 1 ton will be.

Imperial ton (2240lbs (pounds)) divided by 1000 = 2.24lbs

                           or

Metric Tonne (1000kg (kilos) (2205 approx. lbs))  divided by 1000 = 1kg (2.205lbs)


John
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Bunkerbarge

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Re: weight
« Reply #6 on: December 29, 2008, 04:51:32 PM »

You're probably right John and in most exams you would get the majority of the marks for the method rather than the correct answer ;)
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Ow Abreast

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Re: weight
« Reply #7 on: December 29, 2008, 07:25:16 PM »

Thank you lad's so it's 2.24 imperial lbs
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Sandy Calder

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Re: weight
« Reply #8 on: December 29, 2008, 09:09:24 PM »

Thank you lad's so it's 2.24 imperial lbs
Given the pedantic nature of the replies I could keep this going and say 2 lb 4oz. :}
Next?
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derekwarner

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Re: weight
« Reply #9 on: December 29, 2008, 09:19:56 PM »

mmmmmmmmm >:-o Hi all.......bogstandard & I understand how our younger genertations X & Y get confused...as they are taught it's OK to make a mistake ....just as long as the theory is correct  <*<

Just imagine after graduating from those "Schools of Learning" & needed to order a batch of concrete.....teleponed & ordered 10 cubic metres...two 5 CM trucks turn up......& says to the driver  :embarrassed: :embarrassed: :embarrassed: :embarrassed: but why two trucks? I only need enough concrete to fill 1M x1M 1M

The customer was last seen with a pair of 4.5 CM cement boots....................Derek





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Derek Warner

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Colin Bishop

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Re: weight
« Reply #10 on: December 29, 2008, 09:30:38 PM »

Yes, I do think that's where modern education has gone a bit off the rails. In the real world, it isn't enough to master the method - you have to get the actual answer right - or people could die!

Colin
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dougal99

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Re: weight
« Reply #11 on: December 30, 2008, 02:00:45 PM »

Colin

In 1969 (swing that lamp) one of my clerks ordered 10,000 rivets, or so he thought. The order unit was quarter pounds!!

He didn't get the method right, let alone the answer.

He was a product of sixties schooling as was I. When I took my GCEs in maths and physics I was told there were 90% marks for method and only 10% for the correct answer. Plus ca change n'est pas?

Cheers

Doug
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Max Power

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Re: weight
« Reply #12 on: December 30, 2008, 03:47:31 PM »

Colin

In 1969 (swing that lamp) one of my clerks ordered 10,000 rivets, or so he thought. The order unit was quarter pounds!!

He didn't get the method right, let alone the answer.

He was a product of sixties schooling as was I. When I took my GCEs in maths and physics I was told there were 90% marks for method and only 10% for the correct answer. Plus ca change n'est pas?

Cheers

Doug
In the 1960's one of our now defunct British car manufacturers used to order castings and forgings from their suppliers by the ton. This meant that the suppliers produced castings and forgings with the MAXIMUM machining allowance! Car manufacturer then had to machine of the excess. A change of policy in the late 60's saw the castings being ordered in specified numerical quantities. The castins etc soon started arriving at the car manufactures with the minimum machining allowance! Less machining less waste!

By the way it is important that one knows HOW to get the correct answer, if not it is only pure luck and the luck may not hold out the next time :o
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tobyker

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Re: weight
« Reply #13 on: December 31, 2008, 10:26:58 PM »

Or to quote the immortal Tom Lehrer - "the important thing is to understand what you're doing, rather than to get the answer right".(New Math)
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BarryM

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Re: weight
« Reply #14 on: January 01, 2009, 11:01:19 AM »

Just a point but what kind of 'ton' are you starting with?  Deadweight, lightweight, gross, nett, displacement (light or loaded), Suez Canal, Builders Old Measurement (94 cub.ft. per ton) or register (100 cub.ft. per ton)? If you get this wrong at the start it would have 'interesting' results in model format.

Barry M
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Bryan Young

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Re: weight
« Reply #15 on: January 01, 2009, 06:01:20 PM »

Just a point but what kind of 'ton' are you starting with?  Deadweight, lightweight, gross, nett, displacement (light or loaded), Suez Canal, Builders Old Measurement (94 cub.ft. per ton) or register (100 cub.ft. per ton)? If you get this wrong at the start it would have 'interesting' results in model format.

Barry M
Hi, Barry.....been down this road before, I think! BY.
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Ghost in the shell

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Re: weight
« Reply #16 on: January 01, 2009, 06:15:36 PM »

if you are trying to get a scale ship to be a scale weight, FORGET IT, it wont work due to the density of the water.  best thing, pile your weight low in the hull until you hit the waterline that your plans dictate
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Colin Bishop

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Re: weight
« Reply #17 on: January 01, 2009, 06:56:56 PM »

Ghost, if you build a scale model ship then the weight, as expressed in terms of displacement in water, will be to the cube root scale of the original ship and it should sit at the scale waterline in calm water near as makes no difference. However, you are quite right that the model will not behave like the real vessel as the viscosity of water does not scale down and it is therefore "thicker". It's just one of those things that you cannot do anything about, just like when you scale down a sailing ship, the hull volume goes down by the cube root of the scale but the sail area only goes down by the square root so the model is hopelessly "over canvassed" in real time wind conditions. Hence the need for an external keel.

A separate issue is of course centre of gravity. The constructional weight distribution in a model is usually a lot different to its full size counterpart, usually on the side of being top heavy, so ballast usually has to be carried very low in the model. In a full size ship this would result in a very rapid roll period which would make the vessel very uncomfortable and possibly strain the structure.

Just goes to prove that model making is as much an art as a science!

Colin
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BarryM

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Re: weight
« Reply #18 on: January 01, 2009, 07:51:54 PM »

Just a point but what kind of 'ton' are you starting with?  Deadweight, lightweight, gross, nett, displacement (light or loaded), Suez Canal, Builders Old Measurement (94 cub.ft. per ton) or register (100 cub.ft. per ton)? If you get this wrong at the start it would have 'interesting' results in model format.

Barry M
Hi, Barry.....been down this road before, I think! BY.

Very true Bryan but the wheel is often reinvented here. I was also wondering if anyone would bite at "Builders Old Measurement".  ;)
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malcolmfrary

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Re: weight
« Reply #19 on: January 01, 2009, 10:48:25 PM »

If you do an actual scale model ship, and it floats at waterline, it will be the correct scale weight.  It just helps if you know in advance what that weight should be. 
We do have the stability issue as mention previously, but our stuff tends to be much more solidly built than the original.
If you build a model railway engine, and it is heavy, you shout hooray, if its light, you can add weight.  If your model plane is light, again, shout hooray, if its a bit overweight, there is the option of more power to compensate.  If your boat is heavy, it could swamp and sink.  If light, it might ride high and unstable, take on water and sink.  Ours is the only modelling discipline that requires the model to be the correct scale weight and have the right centre of gravity.
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TCC

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I was reading an old MM the other day.
« Reply #20 on: January 02, 2009, 01:56:01 AM »

and it was talking about how much a scale model would weight if you knew the weight of the orig. The maths went like this:

To find your models weight in lbs.

If your ship weighs 29,700 tons, you times that by 2240 (as in 2240 lbs to a ton) and you get the originals weight in lbs as finding your models weight in tons will be near useless.

Then you find out your scale as a ratio, whether it's 1:128 or 1:144 or 1:96, whatever, you multiply this figure by itself 3 times.

So LION was 29,700 tns, x 2240 (lbs) = 66,528,000lbs. LION was 66,528,000 lbs.

My scale is 1:144. So: 144 x 144 x 144 = 2,985,984

Now get you calculator out and divide the lbs out by the scale: thus:

66,528,000 divided by 2,984,984 = 22.28.

Thus a 1:144 LION will be/should be 22.3lbs. (rounded up)

Now there's a calculation for speed as well.
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Colin Bishop

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Re: weight
« Reply #21 on: January 02, 2009, 11:10:45 AM »

There is indeed a calculation for speed but most people feel that a scale boat doing scale speed doesn't look right or give the correct wave formation. Just another one of those "difficult to scale down" factors!

Colin
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TCC

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Re: weight
« Reply #22 on: January 02, 2009, 12:00:27 PM »

There is indeed a calculation for speed but most people feel that a scale boat doing scale speed doesn't look right or give the correct wave formation.

Colin

Why?  too slow?

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Colin Bishop

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Re: weight
« Reply #23 on: January 02, 2009, 12:56:32 PM »

Yes!
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BarryM

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Re: weight
« Reply #24 on: January 02, 2009, 02:02:40 PM »

On the other hand one has to wonder why some people will build model narrowboats and then operate them at speeds that would put a small budgie into orbit. 

Barry M
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