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Aerodynamics question
What's the ratio of the thrust generated by a hi-bypass turbofan between
what goes out the back and the "propeller" effect of the main fan? The main fans rotate in the same direction. How much torque (P-factor from my flying days in a C-152) do they create? Jim ps - hmmm... do they rotate in the opposite direction south of the equator... grin |
#2
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Aerodynamics question
ps - hmmm... do they rotate in the opposite direction south of the equator... grin No, the planes just flip over and fly upside down. |
#3
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Aerodynamics question
"Jim Anderson" wrote in message ...
What's the ratio of the thrust generated by a hi-bypass turbofan between what goes out the back and the "propeller" effect of the main fan? Depends heavily upon which engine your are considering. However, the trend for a long time was towards ever higher ratios. Truely high bypass engines produce anywhere's from 65% - 85% of their thrust from the fans. The main fans rotate in the same direction. Yes. How much torque (P-factor from my flying days in a C-152) do they create? Can't say for sure. I'd suspect very little. |
#4
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Aerodynamics question
p factor is a resultant of the change of apparent pitch during rotate. When
the rotate occurs, the apparent angle of incidence of the prop blade increases and takes a bigger "bite" out of the air thus producing a net torque. This site give a better explanation http://home.earthlink.net/~x-plane/F...y-PFactor.html or this one which is essentially identical http://www.madsci.org/posts/archives...3940.Ph.q.html "me" wrote in message om... "Jim Anderson" wrote in message ... What's the ratio of the thrust generated by a hi-bypass turbofan between what goes out the back and the "propeller" effect of the main fan? Depends heavily upon which engine your are considering. However, the trend for a long time was towards ever higher ratios. Truely high bypass engines produce anywhere's from 65% - 85% of their thrust from the fans. The main fans rotate in the same direction. Yes. How much torque (P-factor from my flying days in a C-152) do they create? Can't say for sure. I'd suspect very little. |
#5
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Aerodynamics question
Torque isn't the issure with jet engines....the main issue is gyroscopic
effect. Jet angines turn VERY fast (15,000 - 65,000 RPM) This high RPM causes the rotating mass to try and stay stationary inflight, meaning it inhibits changes in pitch and yaw (not roll because roll is about the same axis as the rotating mass) "Jim Anderson" wrote in message ... What's the ratio of the thrust generated by a hi-bypass turbofan between what goes out the back and the "propeller" effect of the main fan? The main fans rotate in the same direction. How much torque (P-factor from my flying days in a C-152) do they create? Jim ps - hmmm... do they rotate in the opposite direction south of the equator... grin |
#6
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Aerodynamics question
Thanks Steve and DA...
Kinda nice to get back to some relevant subject matter. J "Steve" wrote in message . .. Torque isn't the issure with jet engines....the main issue is gyroscopic effect. Jet angines turn VERY fast (15,000 - 65,000 RPM) This high RPM causes the rotating mass to try and stay stationary inflight, meaning it inhibits changes in pitch and yaw (not roll because roll is about the same axis as the rotating mass) "Jim Anderson" wrote in message ... What's the ratio of the thrust generated by a hi-bypass turbofan between what goes out the back and the "propeller" effect of the main fan? The main fans rotate in the same direction. How much torque (P-factor from my flying days in a C-152) do they create? Jim ps - hmmm... do they rotate in the opposite direction south of the equator... grin |
#7
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Aerodynamics question
Steve writes
Torque isn't the issure with jet engines....the main issue is gyroscopic effect. Jet angines turn VERY fast (15,000 - 65,000 RPM) This high RPM causes the rotating mass to try and stay stationary inflight, meaning it inhibits changes in pitch and yaw (not roll because roll is about the same axis as the rotating mass) Interesting. Would forces due to precession be at all significant? -- Simon Elliott http://www.ctsn.co.uk/ |
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