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One for the maths gurus


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area of a circle = pi x radius^2

radius = diameter / 2 so 43mm for big hole and 10mm for little hole

pi = 3.141592653589 (if you want to be picky)

so 5808.80481mm2 for the big hole (43 x 43 x 3.141.....)

314.15927mm2 for the little hole (10 x 10 x 3.141.....)

so approximately 18.48999906 of em to be moderately accurate

Gettin' old and forgetting your sums eh old chap? :P:ph34r:

Edited to expand on my calculations/accuracy to prove I am right in the light of later answers :P:lol:

Edited by BogMonster
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Area of a circle = Pie(Radius Squared)

There (22/7) x (43x43) = Area of large circle, divide this by

(22/7) x (20x20) = Area of little circle

OK

Er

no

last one should be 10x10 not 20x20, 20mm is the diameter not the radius :P;)

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4.6 holes so 5 holes will do

I suppose I shouldn't try and do complicated mathematics after being awake for 18+ hours and before sleeping. Please ignoe this post hangs head in shame :D

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HAHAHA

So somewhere between 4.6 and 18 holes then !!

Make yer minds up please :D

<drum fingers mode on>

Nige

Ignore them

I got a B in a level maths and I guess the others all failed it :P;)

Edited my original post above to add some accuracy :P

I should make it 20 holes because the airflow at the edge of the hole is probably less smooth than the blah of the wibble linear turbulent flow coefficient aerodynamic efficiency frictional heating throughout the airflow range leading to less than perfectly laminar flow across the outer 15% of the hole area etc etc

Just drill about 20 holes then :)

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Nige,

The bit that Boggy said:

the blah of the wibble linear turbulent flow coefficient aerodynamic efficiency frictional heating throughout the airflow range leading to less than perfectly laminar flow across the outer 15% of the hole area etc etc

is the important bit.

Flow through lots of small holes will be less efficient than through one large one so I'd go for more rather than less as it were...... :ph34r:

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^^ what he said. Your big hole has only got one edge to disrupt the flow, so you need rather more smaller holes. Although I wouldn't normally consider mentioning it, the thickness of the plate will also have an effect on the formation of the boundary layer :ph34r:

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HAHAHA

So somewhere between 4.6 and 18 holes then !!

Make yer minds up please :D

<drum fingers mode on>

Nige

So now send me some tube for laser cutting the holes. However, to confuse matters you could have slots, slots at an angle, triangular shape, square, shape, 5,6,7,8 sided shapes, text, maybe NIGE in Times New Roman, in fact any old shape you like. Now how about the mathematicians working thet one out! Or should we use some Cad surface generation software?.....................................

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Agree with 19 holes. Charles & John got in there before me with the turbulance around smaller holes issue.

If there is space, I would go for close to 40 holes if you can. Probably overkill - but better than throttling (you need all the power you can get I'm told ;) )

Si

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So now send me some tube for laser cutting the holes. However, to confuse matters you could have slots, slots at an angle, triangular shape, square, shape, 5,6,7,8 sided shapes, text, maybe NIGE in Times New Roman, in fact any old shape you like. Now how about the mathematicians working thet one out! Or should we use some Cad surface generation software?.....................................

We can all see who got a new toy for Christmas Dave! :rolleyes:

No-one likes a show off! :P

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Or just tie a bit of chicken wire over the front of the drainpipe. Then it is nearly all hole :)

Actually chicken wire would look a bit rough, but some sort of welded mesh might be worth looking at, if all you want to avoid is sucking up small furry animals from nearby trees when you mash the pedal to the floor? That's basically what the Safari has got in the front, a diamond-pattern mesh on the intake, plastic rather than metal but no reason you couldn't do something in metal.

Also, rather than using round holes, if NAS90 or whoever has got something that can laser cut a series of holes accurately then taking the bit of metal that is going to form this "filter" and lasering a series of square holes in a grid pattern would fit a lot more "hole" into the same frontal area, than a series of round holes.

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Or just tie a bit of chicken wire over the front of the drainpipe. Then it is nearly all hole :)

Actually chicken wire would look a bit rough, but some sort of welded mesh might be worth looking at, if all you want to avoid is sucking up small furry animals from nearby trees when you mash the pedal to the floor? That's basically what the Safari has got in the front, a diamond-pattern mesh on the intake, plastic rather than metal but no reason you couldn't do something in metal.

Also, rather than using round holes, if NAS90 or whoever has got something that can laser cut a series of holes accurately then taking the bit of metal that is going to form this "filter" and lasering a series of square holes in a grid pattern would fit a lot more "hole" into the same frontal area, than a series of round holes.

Plan 3 is good enough for me.....20mm cutter and a milling machine.

Wait and see if it works,

getting P*ssed off with this snorkel I can own uo to and admit :angry:

FFS

Nige

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