Originally Posted by
Vertical Freedom
Why is the C have lower ROD compared to the D when the D has 1 extra MR blade?? & how about the E & the 530FF? Amazing machines, the sexiest machines by far!
I dont know anything specific about the 500’s, but as aerodynamics and kinetics decide things it mainly works like this:
-For the same type, heavier makes rate of descent decrease. There is more potential energy stored in altitude, which can be used to drive the rotor/ produce lift. And the other way, Lower weights means higher rate of descend.
-Between aircraft types, a few number of long blades makes the power needed go down, and many short blades makes power needed go up. For same weight the helo with fewer and longer blades will be conservative of the stored potential energy from altitude, and need less rate of descend to drive the rotor. Same weight but higher number of blades and shorter, more power needed will make rate of descent higher to get the power to drive the rotor.
”Solidity” is a term for how much the blade area cover from the total disc area. High solidity = high rate of descent, low solidity low rate of descent.
Rate of descent will often be in the 1500-2500fpm range. If I recall the Bell 206, it was around 1500fpm?
As a guess, R22/R44 should also be in the low range.
Also rate of descend (ROD) is not a fixed value. Changing speed and rpm in autorotation changes ROD. At the Vy speed the ROD will be lowest, and att high rpm and VNE/ for auto, it will be highest.
The values given, and also the answer from H500, would be in ”normal” auto, normal IAS and normal Rotor RPM.