To: helmet fire
Here are my responses to your points A through G:
A) Sideslip according to the Robinson POH is to be avoided as it and out of trim flight will result in high flapping loads and cause mast bumping. The application of left cyclic during recovery from a zero g condition is to be avoided because it can result in high flapping loads causing mast bumping. Application of left cyclic or any other direction when flying within the normal envelope will NOT cause high flapping loads. This is why I differentiated sideslip and left cyclic during zero G recovery from the use of cyclic under normal conditions.
B) Please read A) above. If you have an argument with this then I would suggest you contact Robinson or, get a copy of the POH looking under section 4 (last page-unnumbered) and Safety Notice SN-11 as those are the sources that I quote.
C) It is true that the disc does not behave wildly under a zero G condition it is only if you apply left cyclic during the recovery that the flapping loads and frequency increase to the point of mast bumping. Once again this is in the POH.
D) If you can accept the possibility of there being an 18-degree offset in the controls when flying forward to compensate and allow the helicopter to fly forward then, you must understand that the pilot has inputted right cyclic to accomplish this. If in the recovery from a zero G incident the pilot pulls the cyclic aft in accordance with the POH he will have a right bias in his control input. It is this right bias that will add to the already prominent right roll and cause the helicopter to violently roll to the right. It is at this point experience comes into play. The highly experienced pilot can load the rotor and keep rolling the helicopter and bringing it back into stable flight. The inexperienced pilot will try to correct the roll before fully loading the rotor and cause mast bumping. Any application of left cyclic during recovery from zero G will result in mast bumping and under normal recovery from zero g there is a right roll component. If the 18-degree offset comes into play the condition will be further exacerbated.
I believe that this is why Tim Tucker told his students to add a tad left cyclic during recovery from zero G. He ,if I am correct was telling his students to compensate for the offset.
E) I was manager of Technical Assistance for Bell Helicopter International for three years and I was very aware of rotor loss and mast bumping on Bell Helicopters. At my last count during my association with Bell there had been 63 mast separations on several different models. It was during that time that Bell put rubber bumpers on the heads and strengthened the masts on the 205s. The Robinson has experienced over 30 mast separations to my recollection.
F) The Robinson POHs address sideslip and out of trim flight as two different things both of which should be avoided. The Normal Rotorcraft certification document also addresses the demonstration of out of trim and sideslip as two different things both of which must be demonstrated for certification.
G) Once again your argument is with the Robinson POHs and not with me.
Your final paragraph is answered above.
[ 31 October 2001: Message edited by: Lu Zuckerman ]