Water gun power

[cantab]

Now for some data.

0.5 p g = 4905 kg m^-2 s^-2 EDIT: fixed dimensions
That is the conversion factor from isoaker values to my Pe values.

Pe:

1) 1354 W - Supercannon II (riot blast)
2) 434 W - Supercannon II (stream nozzle)
3) 66 W - CPS 2000
4) 17 W - Arctic Blast (riot blast)
5) 1.47 W - Artic Blast (stream nozzle)

Ei:

25% - SCII stream
12.7% - SCII riot blast
7.7% - CPS 2000
6.4% - AB stream
2.4% - AB blast

Es:

135% !!! - SCII riot blast. As I said, efficiency greater than 100% should be impossible...
22% - SCII stream
345% !!! - CPS 2000. Something is going wrong...

[SSCBen]

I thought I made a reply to this but I must have not.

Interesting thoughts. I'm not completely sure your power formula represents power use and the impossible efficiencies seem to verify that. The effective power (energy loss from drag, etc.) should be correct but I'm not too sure your power formula is. Perhaps it would be best to avoid the stream efficiency altogether and use your overall efficiency formula which seems correct.

I'd like to note though that the power formula I posted really isn't useful for much in water guns other than comparison and when the amount of energy or energy transfer is limited in some way. The formula P = p*Q is most useful in water guns with pumps in continuous operation. It'd be rather simple to calculate the efficiency in that case (n = 1 - p*Q/Pin). But still, that's doesn't describe how efficient the water gun is at making water streams shoot far, which is what matters to us.

[cantab]

Yeah, _something_ is evidently wrong. It might just be a really dumb error.

If I get the time I'll try and re-analyse from first principles.

If stream efficiency is wrong then overall efficiency is wrong, since it uses stream efficiency.