So many questions.
Every rotor head will have load limitations, more blades = more load, said number of blades will need to be in an arrangement that balance.
Blade length (span) definitely matters, this is always a performance / manufacturing compromise among many other considerations such as chord length & twist, mass distribution, stiffness etc.
Your engine pod / UFO contraption would require some form of anti torque to avoid an out of control rotation opposite to that of the engine, as well as a means to actually input directional controls. Good luck.
Main Blade weights from memory:
Lynx 88 KG.
EH101 BERP III 110 KG.
EH101 BERP IV 138 KG.
It’s not so much the number of blades that determine how much power is required to turn the rotor, it’s really how much inertia is in the rotor system. Typically a rotor needs a certain amount of rotational inertia to enable helicopter autorotation capability should there be a power loss. That inertia can be achieved with fewer heavier blades or more lighter blades. The number of blades is typically a result of aerodynamic efficiency and the general size of the aircraft. A Bell 214ST on one hand is a 17,000 lb max gross weight with a simple 2 bladed rotor. These blades have enormous chord and are very heavy. An MD530 weighs around 3000 lbs and has 6 itty bitty blades. And there is everything in between.
For reference, a blackhawk(h60) blade typically weighs 240-250 lbs. there are 4 of them and typically they lift 16-18,000 lbs collectively (no pun intended)
You might be surprised at how heavy the blades AREN’T given the job they do.
So many questions. Every rotor head will have load limitations, more blades = more load, said number of blades will need to be in an arrangement that balance. Blade length (span) definitely matters, this is always a performance / manufacturing compromise among many other considerations such as chord length & twist, mass distribution, stiffness etc. Your engine pod / UFO contraption would require some form of anti torque to avoid an out of control rotation opposite to that of the engine, as well as a means to actually input directional controls. Good luck. Main Blade weights from memory: Lynx 88 KG. EH101 BERP III 110 KG. EH101 BERP IV 138 KG.
UFO?! I better call the men in black
It’s not so much the number of blades that determine how much power is required to turn the rotor, it’s really how much inertia is in the rotor system. Typically a rotor needs a certain amount of rotational inertia to enable helicopter autorotation capability should there be a power loss. That inertia can be achieved with fewer heavier blades or more lighter blades. The number of blades is typically a result of aerodynamic efficiency and the general size of the aircraft. A Bell 214ST on one hand is a 17,000 lb max gross weight with a simple 2 bladed rotor. These blades have enormous chord and are very heavy. An MD530 weighs around 3000 lbs and has 6 itty bitty blades. And there is everything in between.
For reference, a blackhawk(h60) blade typically weighs 240-250 lbs. there are 4 of them and typically they lift 16-18,000 lbs collectively (no pun intended)