Quote:
Originally Posted by JamesCH95
Don't get caught up in the details with props and their inefficiencies, sizes, etc. Do the broadest, most basic calculation possible to check and see if it is within the realm of feasibility.
If we take a minimum robot mass (25lbs) and use the entire cross sectional area of the robot envelop, 28inX38in we find that we will need to generate approximately 0.0235psi (162Pa) of dynamic pressure just to 'hover' in free air, ignoring ground effects.
Pdynamic = ( fluid density * fluid velocity^2)/2
fluid density = 1.18kg/m^2 (~STP)
Pdynamic = 162Pa
Fluid Velocity => 16.9m/s
Total air flow rate is 28in*38in*16.9m/s = 11.6m^3/s
In a basic sense we need enough power to accelerate 11.6m^3 of air to 16.9m/s in 1s. This can be simplified to a basic energy problem:
Air mass = 11.6m^3*1.18kg/m^3 = 13.7kg
air velocity = 16.9m/s
Air's kinetic energy = 1/2*mass*velocity^2 = 1950Joules
Time available to apply this energy = 1s
Total power required by this method = 1950J/1s = 1950W to maintain hover, including no inefficiencies.
This is about what PAR_WIG1350 figured that eight motors, drawing well over 280A, could produce.
It is technically unfeasible with our legal battery. It is technically unfeasible with our required main breaker. Even if these barriers were removed, the motors would not last long at peak power.
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With the exception of the battery, the limits are all purely thermal, Through strategic placement of the breakers and motors the propwash might keep them cool enough to avoid anything failing mid-match.
Also, I find it strange that you bring up ground effects while referencing a post made by someone with a ground effect related username.