Why aren’t there airplane sized helicopters? Helicopters seem better in terms of no long runway needed, and the ease of moving in any direction.



Why aren’t there airplane sized helicopters? Helicopters seem better in terms of no long runway needed, and the ease of moving in any direction.

In: Engineering

Basically a helicopters propellers are pushing the helicopter off the ground. The larger the aircraft the larger the propeller you would need. Once you start getting larger you have to consider the amount energy needed to turn it. The material that would be usable for a propeller that wouldn’t snap from force, etc.

I don’t know what you mean by airplane sized helicopters. There are airplanes from the size of a go kart and helicopters over 200,000 lbs. Basically helicopters are extremely inefficient, extremely high maintenance and very slow if you don’t need to hover.

Youd need to find a way to make industrial windmill size propellers spin at helicopter speeds. The amount of power needed would be absurd, we might as well go to Mars with that much thrust

I’m assuming you’re talking about passenger seized planes. Jet fighters are much closer in size to helicopters than they are to passenger jets.

Helicopters are more maneuverable than airplanes, but even the fastest helicopters are much slower than the usual passenger jet would be. It would be too expensive and too slow for regular passenger travel.

Runways aren’t a huge deal because you only need to build them once and you can use them for years and years. While runways and roads aren’t exactly the same, people are very good at building long flat things. The ratio of runway cost to runway usage is pretty good.

Also, passenger planes don’t need to move any direction – they basically just go in a straight line to wherever they are going.

As for jet fighters, they are *way* faster than helicopters, and also very maneuverable in their own right. This gives them an advantage in combat that the most maneuverable helicopters wouldn’t have.

It’s because it would require too much fuel to keep it up and going, the propeller would be gigantic and it wouldn’t have the same efficiency, airplanes require less fuel than the helicopters of the same size because they focus all their vroom vroom power to push it in front, while an helicopter has to push his vroom vroom both upwords and forward, requiring a lot more fuel

There are airplane sized helicopters such as the https://en.wikipedia.org/wiki/Mil_Mi-26 which can carry 90 troops at once.

Helicopters are terribly inefficient as a means of moving through the air. Airplanes have wings that provide the lift they need to stay aloft; wings work even when the engines are not working. Airplane engines just have to overcome the backward drag of moving through the air, while a helicopter engine has to produce enough downward thrust to keep the helicopter in the air, and the helicopter has to burn fuel to make that thrust, while the airplane is basically just coasting along keeping itself going forward. As a result helicopters us a LOT of fuel compared to airplanes to move the same weight the same distance. The reason helicopters get used is because sometimes it’s needed to be able to get off the ground without having a long runway to build up speed. So you often see helicopters fly people from downtown to the airport to get on a plane. The helicopter is faster and more convenient than a car for the trip, but a lot more expensive than the car. The helicopter simply couldn’t carry enough fuel to cross an ocean, for example, and helicopters can’t go nearly as fast a planes, either, for reasons!

Physically, the big reason is the speed of sound.

Typically, you don’t want the tips of helicopter blades to go past the speed of sound, as it causes instability and less lift from the blades. So if you make the blades longer, they have to turn slower to keep their speed below the speed of sound. If you make the blades wider for more lift, it makes the rotating mass much heavier, which domino’s to make the whole drivetrain much heavier. That’s why ‘heavy lift’ helicopters have two main sets of blades. Additionally, say your blades rotate150mph below the speed of sound. It means that you can only move at 150mph horizontally before the blades go past the speed of sound as they rotate from the back to the front of the aircraft. So you can only easily make helicopters so big and so fast; planes have much higher limits on both of those factors.

FWIW, A CH-53K is almost as long as a 737.

Compared to a fixed-wing aircraft, the rotary wing is slower, less fuel efficient, louder, and has a shorter range. So, the farther you need to go, the less attractive the helicopter becomes. The helicopter is really relying on brute force to stay airborne.

Helicopters are a slower and significantly less efficient way to travel. They are also less reliable and require a lot more maintenance to keep safe. This far outweighs any advantage a vertical takeoff and increased maneuverability might provide.