Cadman’s Hydrostatic Displacement Engine

[tinman]

Thank you Graham!!

Graham made an error in his calculations-but easy to make.

Brad

[Grumage]

Graham made an error in his calculations-but easy to make.

Brad

Thanks Brad, indeed there was.

The bore diameter is 3/4" in the video equating to 8:1 ratio. So the piston length should have been 6".

Cheers Graham.

[Cadman]

For your entertainment.   

https://www.youtube.com/watch?v=aTOJpDBS1Bw

Thank you very much Graham!

As happy as I am to see that, I believe there is an error, but one that could easily be correted.

This is how I figure it: and please someone correct me if this is wrong
area of your 3/4" piston with a 1/8" hole is 0.4295 sq in
area of my 6" piston with a 3/4" rod is 26.4126 sq in
that gives a ratio of 61.4962 to 1
the scaled piston assembly weight would be 0.2764 lbs or 125.39 grams. (17 / 61.4962)
I get 5" piston length at 1:8 scale. (40 /8)

And BTW, you don't need to grease the rod, that just adds resistance. It will either displace the water or not.

If my figures are correct, would it be too much to ask for you to drill partial holes around your center hole in your rod until it weighs 125 grams, then rerun your test?

It would be very appreciated and save me a lot of work if you can.

Regards,
Cadman

PS steel weighs 0.283 lbs per cu in. or 128.37 g

[lumen]

The answer is very simple. The displacer is exactly what it must do (in this case ) displace water.
In the vertical position it will sink (displace water) only until the water it displaces equals the weight of the displacer.

Not hard to understand.
To displace water for the entire length of the displacer would require it to weight as much as it's exact volume in water.
If it does not, it will sink only to a point where the water it displaces is equal in weight to the displacer.

I think this will be a problem unless it can be done in an additional step just to raise the displacer.

[Grumage]

Thank you very much Graham!

As happy as I am to see that, I believe there is an error, but one that could easily be correted.

This is how I figure it: and please someone correct me if this is wrong
area of your 3/4" piston with a 1/8" hole is 0.4295 sq in
area of my 6" piston with a 3/4" rod is 26.4126 sq in
that gives a ratio of 61.4962 to 1
the scaled piston assembly weight would be 0.2764 lbs or 125.39 grams. (17 / 61.4962)
I get 5" piston length at 1:8 scale. (40 /8)

And BTW, you don't need to grease the rod, that just adds resistance. It will either displace the water or not.

If my figures are correct, would it be too much to ask for you to drill partial holes around your center hole in your rod until it weighs 125 grams, then rerun your test?

It would be very appreciated and save me a lot of work if you can.

Regards,
Cadman

PS steel weighs 0.283 lbs per cu in. or 128.37 g

You're most welcome.   

Brad and I have been in conversation about the issue already.

So the piston needs to be 5" long and approximately 125 g in weight?

Cheers Graham.