Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Cherlie on June 14, 2002, 06:04:17 PM
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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
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They turn really really fast, and then the plane moves forward.
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I know that, but how does the plane move forward? what does the propellar do to cause it to mvoe forward?
CharlieB
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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.
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google is your friend (http://beadec1.ea.bs.dlr.de/Airfoils/propuls4.htm)
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.
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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.
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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 :)
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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
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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
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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.
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lol Animal! Gonna remember that one everytime I hear the word 'torque' now. :D
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Originally posted by Curval
lol Animal! Gonna remember that one everytime I hear the word 'torque' now. :D
hehe, real horrorshow explanation.
just give credit to HiTech.
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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.
:D
Daniel
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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;)
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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.
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A flat prop at the correct angle with enough power will drive the airplane forward. It is the mechanics of angle, that is, the screw, that makes propellors work. Airfoil shapes just make it more efficent.
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Originally posted by Animal
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 :)
Hmmm.. The "Pee Factor" strikes again.
This might help in understanding the thrust vectors of a propeller.
http://yarchive.net/air/airliners/p_factor.html (http://yarchive.net/air/airliners/p_factor.html)