Timeline for Are the gyroscopic precession and P-factor of a pusher propeller in opposite directions?
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Sep 7, 2021 at 0:15 | comment | added | alireza | thank's a lot my friends 🌹🌹🌹 | |
| Sep 6, 2021 at 20:30 | comment | added | John K | Yes you just flip it right to left. 3 o'clock becomes 9 o'clock. | |
| Sep 6, 2021 at 19:12 | comment | added | Jpe61 | So I think the effect is 180 degrees different? | |
| Sep 6, 2021 at 19:11 | comment | added | Jpe61 | @JohnK in alizera's example the rotation of the propeller is opposite to "normal", as it is a pusher, the blade going downwards would be the blade at 9 o'clock. | |
| Sep 6, 2021 at 19:02 | comment | added | John K | @alireza The part of the disc with the greatest thrust is 3 o'clock looking from behind because the blade passing 3 has the highest angle when the prop axis is at a positive angle to the airstream. If you are slipping to the left, that is left wing down, with a positive AOA, the relative airflow goes from straight on from below, to offset to the left from below; 6 o'clock to 7 o'clock. The propeller disc sees its maximum blade angle shift from perpendicular to 6 o'clock to perpendicular to 7 o'clock, or from 3 o'clock to 4 o'clock. In that case P factor would create a slight NU tendency. | |
| Sep 6, 2021 at 17:38 | comment | added | alireza | @john k when an aircraft yaws to the left this means that relative airflow now coming from the right (negative yaw and positive side slip), in positive side slip , which part of propeller disk have greater thrust? right side of propeller or left side? can you describe this in details? | |
| Sep 6, 2021 at 17:37 | comment | added | Jpe61 | My takeoffs were always silky smooth, so never noticed that 😃 | |
| Sep 6, 2021 at 17:12 | comment | added | John K | @Jpe61 precession forces can be much stronger, as you discover if you raise the tail of your C-180 very quickly on takeoff. and the nose swings hard from precession, but that's a brief transient state anyway. | |
| Sep 6, 2021 at 17:10 | comment | added | John K | They may cancel each other in a transient condition, but only while yawing/pitching. Side slip will change the P factor's orientation somewhat, to the extent that the airflow has changed relative to the propeller axis. Say the flow is now coming from 7 o'clock due to side slip instead of 6. The P factor force orientation should move from 3 o'clock to 4 o'clock during the slip, to the extent that you have power on during the slip. | |
| Sep 6, 2021 at 17:06 | comment | added | Jpe61 | Precession is not, if I reacall correctly, mentioned in pilot training, so it must be negligible. I'm guessing P-factor is at least an order of magnitude greater. Sideslip would have some effect. In this case, flying "left side first", it would push the nose down. | |
| Sep 6, 2021 at 16:47 | comment | added | alireza | that means they cancel each other? what's the effect of side slip on p factor? | |
| Sep 6, 2021 at 16:27 | history | answered | Jpe61 | CC BY-SA 4.0 |