iChris Posted March 10, 2014 Posted March 10, 2014 (edited) Call me crazy, but I've been flying for a long time and this is what I've experienced. And helicopters like the JetRanger and LongRanger do not exhibit positive dihedral effect. In the case of a helicopter most of the dihedral effect comes from the flapping of the rotor; however, some of the effect comes from the airframe components. Q: What is the purpose of the stabilizer finlets on models 407 and 206L series helicopters? A: The purpose of the finlets (aka auxiliary fins) is to improve the dihedral stability of the helicopter, namely to remove the tendency to roll from side to side in flight. The auxiliary fins are offset slightly to the left so they are parallel to the direction of the rotor wash in forward flight at cruise airspeed, thus reducing drag. REF: Bell helicopter "Rotorbreeze" Page 10 In the case of the R44, fixed floats below the CG reduces the normally positive dihedral damping, the result is a adverse roll characteristic during side slipping, therefore the caution: R44 FIXED FLOATS SUPPLEMENT Flight characteristics and handling qualities with inflated floats are more critical than with conventional landing gear. Helicopters with floats installed have an adverse roll characteristic. When sideslipping nose right or left, the helicopter will tend to roll in the opposite direction out of the turn. This could be extremely dangerous if a pilot failed to apply right pedal or put in the wrong pedal during a simulated power failure. Also, aerodynamic lift produced by floats makes both RPM and pitch control more difficult during auto rotation entries. Helicopters with floats installed are also more gust sensitive and difficult to fly in turbulence. Edited March 11, 2014 by iChris Quote
CharyouTree Posted March 11, 2014 Posted March 11, 2014 When you tilt the disk with respect to the helicopter, it will generate a roll rate and the helicopter will continue to roll while you hold the cyclic stick displaced from its initial trim position. After the desired bank angle is achieved, the stick is returned to the initial trim position. In order to level the helicopter, the cyclic must be displaced laterally, opposite the turn, thereby rolling the helicopter level then returning the cyclic to its initial trim position, technically lateral cyclic stick commands roll rate. You're both right. In a 206, it's as you described. In a Sikorsky (at least an H-60), I hold the cyclic in the direction of the turn, and return to neutral to level. May be due to some of the systems on board, though... Quote
iChris Posted March 11, 2014 Posted March 11, 2014 (edited) You're both right. In a 206, it's as you described. In a Sikorsky (at least an H-60), I hold the cyclic in the direction of the turn, and return to neutral to level. May be due to some of the systems on board, though... That's correct, we’re talking about helicopters without AFCS or any other stability augmentation. Depending on the mode of operation, your AFCS enhances the stability and handling qualities of the UH60 helicopter. It is comprised a host of subsystems like: Stability Augmentation System Trim Systems Flight Path Stabilization Stabilator It provides static stability by holding: airspeed, attitude, heading, and coordination while turning. Etc. Edited March 11, 2014 by iChris Quote
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