Propeller vs. Rotor: Exploring the Differences in Aircraft Design

In summary, the difference between the appearance of a propeller on a plane and a rotor on a helicopter lies in the fact that they serve different purposes and have different capabilities. While they may look similar, a propeller is designed to move air horizontally while a rotor blade is used for vertical lift. The shape and twist of a rotor blade is determined by the need for it to be lightweight and adjustable, while a propeller is less adjustable and more fixed in its design. This distinction makes a helicopter a rotary-wing aircraft, rather than a prop driven one.
  • #1
mtworkowski@o
213
0
I was thinking about the difference between the appearance of a propeller on a plane and a rotor on a helicopter. What is the consensus?
 
Engineering news on Phys.org
  • #2
Two different things that live on two separate worlds. They are only similar in appearance and the fact that they move air. What exactly is it you are wondering about?
 
  • #3
I'm thinking these things look different because they're doing different things. I know a propeller is moving air horizontally, but is a copter blade shaped that way because centrifugal force is holding it out?
 
  • #4
If you are referring to their droop while stationary, then you are correct. Because they have such large aspect ratios, to make a rotor blade stiff like a prop you would have to make it extremely thick ad heavy. It would be completely impractical.
 
  • #5
I'm also not seeing the twist that I see on a prop. I know that collective/cyclic controll needs that compromise but is that the reason the twist is not there?
 
  • #6
mtworkowski@o said:
I'm also not seeing the twist that I see on a prop. I know that collective/cyclic controll needs that compromise but is that the reason the twist is not there?

HAH! Good observation. I never noticed that until your post!

Its probably becuase the change in speed due to RPM is much lower than a prop from center to blade tip. -but that's just a guess.
 
  • #7
I'll buy that!
 
  • #8
mtworkowski@o said:
I'm also not seeing the twist that I see on a prop. I know that collective/cyclic controll needs that compromise but is that the reason the twist is not there?
There is a slight twist in helicopter blades, but not a huge twist like in a prop. For example, my beloved Chinook has a negative 12° twist towards the tips. The twist is there to accommodate the large length of the rotor and the resulting change in lift as you go from the hub to the tip. A prop is less like a real wing than a rotor blade. A prop, while can be feathered and adjusted, is less adjustable than a rotor blade which is why there is a huge twist in them, to get the max thrust they can get in their design condition. That is why a helicopter is a rotary-wing aircraft and not a prop driven aircraft.
 
Last edited:

What is the main difference between a propeller and a rotor in aircraft design?

The main difference between a propeller and a rotor is the way they generate lift. A propeller uses its rotating blades to push air backwards, creating a forward thrust. On the other hand, a rotor uses its rotating blades to create lift by pushing air downwards.

Which type of aircraft design is more commonly found in commercial airplanes?

Commercial airplanes typically use a propeller design, as it is more fuel efficient and creates less noise compared to a rotor design. However, helicopters, which are also considered commercial aircraft, use a rotor design.

What are the advantages of using a rotor design in aircraft?

A rotor design allows for vertical take-off and landing, which is useful for helicopters and other VTOL (vertical take-off and landing) aircraft. It also provides better stability and control during low-speed flight compared to a propeller design.

What are some examples of aircraft that use a propeller design?

Some examples of aircraft that use a propeller design include commercial airplanes, small private planes, and some military aircraft. Some notable examples include the Boeing 747 and the Cessna 172.

Can a propeller and rotor design be used together in an aircraft?

Yes, some aircraft designs use both a propeller and a rotor. These hybrid designs are often used in military or experimental aircraft, and they utilize the benefits of both designs for specific purposes.

Similar threads

Replies
34
Views
2K
  • Mechanical Engineering
Replies
14
Views
1K
  • Mechanical Engineering
Replies
23
Views
2K
  • Electrical Engineering
Replies
3
Views
786
  • Electrical Engineering
Replies
4
Views
1K
  • Mechanical Engineering
Replies
1
Views
1K
  • Mechanical Engineering
Replies
5
Views
4K
  • Mechanical Engineering
Replies
20
Views
5K
  • Aerospace Engineering
Replies
9
Views
3K
Back
Top