Why can a helicopter stay on the ground and lift off the ground with the blades spinning at the same speed?

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In other words, if spinning blades super fast doesn’t give a helicopter the lift it needs, then what does?

In: Physics

6 Answers

Anonymous 0 Comments

The angle of the rotors is what changes.

When the pilot pulls back on the collective (the control stick on the left) it changes the angle of the rotor blades which causes them to generate more lift.

If the collective is down the rotor blades rotate to a position where they generate little if any lift.

The same process is true for a lot of propeller aircraft. The speed at which the propeller spins is constant but the angle of the blades changes. This is how they adjust how much thrust the engine generates and also allows the thrust to reverse if necessary like during landing. This is more efficient and faster reacting than the older method of speeding them up and slowing them down.

Anonymous 0 Comments

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Anonymous 0 Comments

A helicopter may have various main control including variac power or throttle, the function of the speed of the rotor as given by both turbulent aerodynamic effect and the inertia of the rotor presumed at the speed of the rotor, and the prop tilt of blade and as well position of the helicopter which the position of the helicopter from a first or third person perspective is seen here with a user position controlled determinant first or third person perspective view which this gives also the boarding of the helicopter by this parameter seventh. As well a helicopter may have an avionics which broadcasts from the helicopter a specific control frequency and the squawk of the radio of the helicopter at that frequency and an autopilot which provides contrary axial torque. Variously internal combustion and turbine engine are used on helicopter which the function of the helicopter takes the power from the turbine engine and yields rotor dependent thrust downward from the rotor which a helicopter also has an ability to roll and tilt left and roll and tilt right and may also occasionally deploy airbrakes at mobility.

To answer your specific question, the rotor speed can be increased or the lift load decreased to allow for the helicopter to get off the ground in a occasion the main speed of the rotor is not enough, which the board of a helicopter in weight unit is maybe 8 weight unit at maximum or two personell not including the two pilot and any autopilot system. A weight unit is 135kg or also 100kg nominal. This is specified for a huey UH-1 which maybe has the capacity for double that or 16 weight unit at maximum. If this does not work then there is the capacity for an increased ground effect modification where the helicopter is sent back to the factory and the increased prop size installed which increases the effective ground effect of the helicopter when in the air which this is especially if the helicopter fails to gain only partial lift then the enhanced ground effect of helicopter rotor prop can increase the helicopter able to fly but this takes about 64 days at the factory if an initial helicopter lift profile is insufficient for the needs to install the larger rotor. If this further does not provide enough lift for the means which then by definition by the specification of a 64 day tune of materiel in real sidereal days from allotment request would provide by definition 4 times the effective load capacity but also render the craft into similar to a Chinook which the allotment of the larger lift capacity is the double rotor mod, which when applied to a black hawk is the chinook mod for the black hawk, with similar avionics specification, and in russian materiel allocation is the skyorsky skycrane allocation when there is the 64 day extra factory time on top of base factory time. This provides some 4 times the lift capacity for the ship, and this 4 times capacity is used for 500kg munition on the AH-64D attack helicopter by default for the boarding of main cannon and hellfire missile onboard this attack helicopter so is not possible to do on an AH-64D because it is already the extra lift mod for the helicopter. As well, maybe a ground crew can do some metalwork on an existing rotor and render it viable but this is probably really difficult.

Anonymous 0 Comments

When you stick your hand out of the window on a car ride, you change the angle of your hand to make the wind lift or drop your arm. Helicopters can do the same thing with their blades, changing their angle mid rotation with the swash plate. That’s what let’s it lift only the front, side, back, or all at once

Anonymous 0 Comments

Why wouldn’t someone just go on YouTube instead of posting here? It seems most ELI5s can be answered by a simple search YouTube.

Anonymous 0 Comments

Some say flying a helicopter is immensely harder than flying an airplane. You are in control of a *lot* of things.

The blades spin fast, and they can spin even faster and still not lift up, what changes is the rotor angle. It’s much more precise than just trying to speed the engine up and down to gain altitude or land quicker.

I love explaining this side of helicopters to people with the example of sticking your hand outside the window of a car (*everyone had to do this at some point, right??)* as you’re going down the road the speed can stay the exact same, but angling your hand upwards or downwards will make your hand ‘fly’

More angle, more ‘fly’, less angle, less ‘fly’, downward angle, down ‘fly’