Power to weight ratio

[Greg Wilson]

Hoping some of you out there may be able to help me with the following:

 

I currently have a ballistic model which produces 440 watts of power and weighs 19.75ounces/563grams. I would like to know the power to rate ratio and the simple formula for calculating this.

 

Many thanks in anticipation!!!

 

Greg

[Marc Humphries]

Hi

Rig the model to some sort of scale / balance to measure the thrust in grams - then divide by the weight.

 

Alternatively (assuming it's an electric model) - down load MotorCalc software (it's free for 15 days or so) and plug in all your parameters and it will do the clever calculations for you.

 

Marc

[Simon Chaddock]

Hi Greg

You have titled this thread Power to Weight.

Well you have that already - A Watt is a measure of power and weight is er weight.

So divide the Watts by the weight and you have the power to weight ratio, that is 440/19.75 which is 22.27 Watts per Ounce, or multiply that by 16 and you get 356.4 Watts per Pound (quite high) or whatever units you choose to use.

 

If you want the thrust to weight ratio then you will need some sort of rig as Marc suggests.

 

[Greg Wilson]

Many thanks Marc and Simon - your help is very much appreciated and has given me the answer I was looking for. I had kind of guessed the calculation but now I have the formula I will be able to apply this to my other electric models which are mostly of my own design.