Re: [Flightgear-users] bo105 - Always turning right?
Dave Martin wrote: I've just about got the hang of the bo105 (I think) but It continually rotates to the right in 'level-cruise'. Helicopters have no built-in stability in yaw. Under different conditions, you need to apply different rudder inputs to counter the main rotor torque and stay pointed in the same direction. I don't know if the magnitude or direction of the zero-rudder rotation is correct, but the general effect (you need to constantly be working the rudders) is definitely right. Andy ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-users] bo105 - Always turning right?
On Mon, 10 Jan 2005 10:42:19 -0800, Andy Ross [EMAIL PROTECTED] wrote: Helicopters have no built-in stability in yaw. I don't know if that's quite right. In hover and slow-speed flight, helicopters have no natural yaw stability (you have to work the anti-torque pedals constantly); however, in cruise, from the pilot's perspective, a helicopter should display the same kind of stability that an airplane does (perhaps a little less, but the same idea). There's a name for the transition from hover to cruise (and probably a better name for 'cruise'), but as a non-rotorhead, I don't know it. That's not to say, of course, that helicopters or airplanes will fly straight without any control input -- both need constant attention to go straight, as Andy suggests. However, in cruise (or whatever it's called), you probably want to use the cyclic (=~ailerons) to control the direction of flight rather than the anti-torque pedals (=~rudder), unless the helicopter isn't actually flying the way it's pointing. All the best, David -- http://www.megginson.com/ ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-users] bo105 - Always turning right?
On Monday 10 Jan 2005 18:42, Andy Ross wrote: Dave Martin wrote: I've just about got the hang of the bo105 (I think) but It continually rotates to the right in 'level-cruise'. Helicopters have no built-in stability in yaw. Under different conditions, you need to apply different rudder inputs to counter the main rotor torque and stay pointed in the same direction. I don't know if the magnitude or direction of the zero-rudder rotation is correct, but the general effect (you need to constantly be working the rudders) is definitely right. Andy ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d That I know. We were discussing that the bo105 always flies in the cruise with bank - any rudder inputs in the cruise just cause deflection from the track. (crabbing) The bo105s non-flapping rotor seems to be the reason for requiring bank to maintain a heading; have a go yourself; no ammount of rudder in any direction in the bo105 with nil-roll will prevent an inexorable turn to the right. Dave Martin ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-users] bo105 - Always turning right?
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Dave Martin schrieb: I've found that the only way to maintain a straight track over the ground is with 10-15deg bank. Based on having watched many helis fly, I don't think they usually bank to maintain track (I could be wrong on this). A fast flying heli will always have a bank angle. Why? A rotor blade produces lift proportional to the speed dof the air around it. When the heli flies foreward, the blades that are also moving foreward (on a clockwise rotating rotor the left side) are producing a higher lift than those that are going backwards. The resulting force will create the bank angle you've experienced. (Or mechanical: the center of lift moves to the side. And the center of gravity -which is fixed- will always be in a stright line below it. So the heli will bank untill these centers are aligned again) CU, Christian -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.0 (MingW32) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFB4BellhWtxOxWNFcRAvi8AJ4rNxSIFL4EuDIvq1BLmwCYK6Y/9wCgmdrT UVhetUB/OqVCxRLTdY2a3U4= =B8g6 -END PGP SIGNATURE- ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-users] bo105 - Always turning right?
Christian Mayer wrote: Dave Martin schrieb: I've found that the only way to maintain a straight track over the ground is with 10-15deg bank. Based on having watched many helis fly, I don't think they usually bank to maintain track (I could be wrong on this). A fast flying heli will always have a bank angle. Why? A rotor blade produces lift proportional to the speed dof the air around it. When the heli flies foreward, the blades that are also moving foreward (on a clockwise rotating rotor the left side) are producing a higher lift than those that are going backwards. The resulting force will create the bank angle you've experienced. (Or mechanical: the center of lift moves to the side. And the center of gravity -which is fixed- will always be in a stright line below it. So the heli will bank untill these centers are aligned again) My rotary wing experience is very limited, but I seem to remember that the advancing/retreating blade effect, which you correctly describe, is at least in part compensated by hinging the blades so that they flap up and down and fore and aft. The helicopters that I flew certainly didn't fly with a noticeable bank angle so far as I remember. It was 20 and more years ago, though. Regards, Vivian ___ Flightgear-users mailing list Flightgear-users@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-users 2f585eeea02e2c79d7b1d8c4963bae2d
