Larger drones that measure 100 mm from motor to motor or 3, 4 or 5 inches across the propeller diameter
can reach speeds of 50 to 80 mph, racers say.
Meanwhile, the required power from the propeller ([P.sub.Prop-Req]) based on the simulated propeller diameter
(Diam) and pitch (Pitch size and propeller revolution per minute (RPM) can be evaluated as given in (19).
where [K'.sub.1] - propeller's coefficient, in case of low ship's speed for calculations could be taken as 0,2; [n.sub.N] - thruster's propeller revolutions, [s.sup.-1]; [D.SUB.N] - thruster's propeller diameter
; t'' - thruster's propeller propulsion coefficient, in case of low ship's speed for calculations could be taken as 0,2.
where [[rho].sub.w] is water density, n is rotational speed, D is propeller diameter
, and [K.sub.T] is thrust coefficient obtained by open-water test of propeller.
Key words: wind-mill motor, propeller diameter
, propeller revolutions, rotor blade
Secondly, the optimisation of the propeller diameter
and shaft speed can be evaluated to see if further efficiency improvements are possible.
velocity, tank diameter, liquid viscosity, propeller diameter
Now, it's known that thrust (T) is related to propeller diameter
(D), propeller speed (n) (revs/sec.), and air density ([rho]), according to the formula
Symbol Description d Propeller diameter
rpm Rotational speed at design condition (rev./min) clm Lift coefficient at r/R = 0.6 clt Lift coefficient at the blade tip Table 4: Values of design variables for example cases.
This area is situated between the two cylinders, first of radius [R.sub.1] which corresponds with the propeller diameter
and the other one of radius [R.sub.2] which corresponds to the interior diameter of the tank, according with Fig.
where [V.sub.A]= inflow velocity, [c.sub.0.7]= chord length at 0.7R, J=advance coefficient ([V.sub.A]/nD), n=propeller rotational speed in rps, and D = propeller diameter
. It is also necessary to keep in mind the minimum propeller size for which models of adequate accuracy for cavitation testing can be built economically.