Author Topic: Question (Read 441 times)

Cherlie · « **on:** June 14, 2002, 06:04:17 PM »

ok this is quite stupid, esp coming from a WW2 plane fanactic.

I know how jet engines work, but I have no idea how properllars work, can someone explain that to me?

CharlieB

Hortlund · « **Reply #1 on:** June 14, 2002, 06:09:34 PM »

They turn really really fast, and then the plane moves forward.

Cherlie · « **Reply #2 on:** June 14, 2002, 06:21:07 PM »

I know that, but how does the plane move forward? what does the propellar do to cause it to mvoe forward?

CharlieB

Maverick · « **Reply #3 on:** June 14, 2002, 06:47:01 PM »

Cherlie,

Do you have a fan in your house? If you do, turn it on and notice what the effect on the air is. It is amplified with an aircraft.

Animal · « **Reply #4 on:** June 14, 2002, 06:53:42 PM »

google is your friend

Its kinda hard to explain on simplified terms.

Its a form of propulsion. The prop creates resistance by pushing the air very fast to the back of the plane, thus pushing the plane forward.

mietla · « **Reply #5 on:** June 14, 2002, 07:10:31 PM »

think of a prop blades as of wings. They have a certain angle of attack and the turning motion creates a n airflow over them. As a result they create a lift perpendicular to their surface, whic pull sthe aircraft forward.

Same thing with a helo.

Animal · « **Reply #6 on:** June 14, 2002, 07:26:59 PM »

Quote

Originally posted by mietla
think of a prop blades as of wings. They have a certain angle of attack and the turning motion creates a n airflow over them. As a result they create a lift perpendicular to their surface, whic pull sthe aircraft forward.

Same thing with a helo.

Thats a good explanation though I dont know if someone who doesnt understand it intuitively will get it that way.
Its one of those things that are easy to understand but hard to explain.

On a related topic, HiTech once explained torque in the most elegant way I have ever read. He compared torque with when you wake up in the morning with an erection, and you go to the bathroom to urinate. When you push your erected noodle down in order to aim at the toilet, the rest of your body wants to go up. Thats torque

Dago · « **Reply #7 on:** June 14, 2002, 07:27:00 PM »

Mietla has it pretty much right. Lift created on the front pulls the prop, and all it is attached to forward. And yes, same as a helo. Thats why a prop/rotors will cone fwd/up as rpm increases and "lift" is increased.

dago

Cherlie · « **Reply #8 on:** June 14, 2002, 07:33:41 PM »

ok don't quite understand it .

I got a fan at home and when I turn it on, air is pushed around forwards, if the angels of the props in the fan were changed, would the air be pushed backwards?

CharlieB

Animal · « **Reply #9 on:** June 14, 2002, 07:53:58 PM »

Quote

Originally posted by Cherlie
ok don't quite understand it .

I got a fan at home and when I turn it on, air is pushed around forwards, if the angels of the props in the fan were changed, would the air be pushed backwards?

CharlieB

YEAH.

Curval · « **Reply #10 on:** June 14, 2002, 08:07:13 PM »

lol Animal! Gonna remember that one everytime I hear the word 'torque' now.

Animal · « **Reply #11 on:** June 14, 2002, 08:12:32 PM »

Quote

Originally posted by Curval
lol Animal! Gonna remember that one everytime I hear the word 'torque' now.

hehe, real horrorshow explanation.
just give credit to HiTech.

CyranoAH · « **Reply #12 on:** June 15, 2002, 04:15:57 AM »

All myth...

Propellers are placed there to ventilate the pilot.

If you don't believe me, go for a ride in a prop-powered plane, stop the propeller and watch the pilot sweat.

Daniel

Monk · « **Reply #13 on:** June 15, 2002, 06:03:17 AM »

Quote

Originally posted by Animal

On a related topic, HiTech once explained torque in the most elegant way I have ever read. He compared torque with when you wake up in the morning with an erection, and you go to the bathroom to urinate. When you push your erected noodle down in order to aim at the toilet, the rest of your body wants to go up. Thats torque

Finally, something I understand;)

LtHans · « **Reply #14 on:** June 15, 2002, 09:24:55 PM »

Propellors have an areodynamic shape cross section to them, just like wings do. A teardrop shape. Curved side forward, flat side on the rear.

Spin the thing. You get the same pressure change that wings do when you move an airplane forward.

They have angle of attack and stall speeds just like wings do, which is why most propellor planes can change the pitch of the blades.

In a nutshell, they are little wings.