to keep going:
Thrust = mass flow * velocity
Power = (1/2) mass flow * velocity^2
For a given thrust, we could pick any combination of mass flow and velocity, but to minimize energy used, we want greater mass flow and less velocity.
max power for a single FIRST motor is 480 watts (12V * 40A). call it 500W for round numbers. So for 50 N you could do, for example, 2.5 kg/s air at 20 m/s. Now, to put this in perspective, 20 m/s = 44 mph. Seems a little high to me, but maybe not out of the question. Probably you wouldn't get anything faster than this. Now put 2.5 kg/s of air in perspective. That's 5.5 lb/s. Since a cubic foot of air has a mass of ~0.075 lb at standard temp and pressure, we need 73 ft^3/s. That's 4406 ft^3/min (scfm). That's a rather large number. Maybe not totally out of the question though.
So, unless I messed up the math, I'd guess that 50N of thrust could be achievable without violating the laws of physics or any FIRST rules, but I don't think it would be cheap or easy...
Quote:
Originally Posted by Bongle
To continue this train of thought and get an idea of what would be possible. Note that neither of these would be legal:
A $2600USD model aircraft jet engine puts out 59N: http://www.trimair.com.au/index2.html. However, it is petrol powered and obviously illegal.
A $740 set of ducted fan components can put out 13-15lbs of thrust (57.9N), but uses a minimum of 3200 watts, which is 6.6 times how much power a FIRST robot can use. |