To: helmet fire
I’ll try to respond to each paragraph as applicable.
We are looking at two different things. Sideslip and cyclic input. Cyclic (left) during recovery from a zero G situation can result in severe flapping. Sideslip in the case of the Robinson can also cause severe flapping. These are not my words they are published in the Robinson POHs for the R22 and R44.
My statement about the disc going wild alluded to the severe flapping when improperly recovering from a zero g situation.
Regarding Tim Tucker, as the test pilot he was required to bring any problems relative to handling qualities to the attention of the engineering group and the certification authorities. This is a requirement of the certification document for normal category helicopters. My question is did he notify Robinson of the problems. I would think that he did not or if he did Robinson did not react to the input. After many mast separations and rotor incursions additional research was performed and it was decided that in order to minimize the possibility of mast bumping the helicopter should be restricted from sideslipping and flying out of trim as both maneuvers would result in severe flapping and cause mast bumping and or rotor incursion.
The certification requirements for normal category rotorcraft require that sideslipping and flying out of trim be demonstrated in order to gain certification. Both the Robinson and the Bell had to demonstrate these maneuvers. It seems that the restriction of the sideslipping of the 205 and 212 sets the maximum speed at which side slipping can be accomplished. This restriction may have come out of the certification trials or later on as a result of an in service problem. The Robinson on the other hand is restricted totally from performing sideslip or out of trim flight at any speed. This was done to minimize the possibility of mast bumping. If you had followed my posts of last year I addressed whether the Robinson design was certifiable. If Frank Robinson were to place the two designs up for certification at this time the FAA would reject the design because they could not meet the certification requirements that dictate the performance of sideslip at 90-degrees and out of trim flight at 10-degrees at a specified speed. My basic question still stands. If the Robinson is restricted from sideslip and out of trim flight now because of the catastrophic results stemming from these maneuvers then how did it get through the certification process without this being discovered?
In accordance with Safety Notice SN-11 when entering zero G the tail rotor thrust will cause the helicopter to rapidly roll to the right. It specifically states not to try to counter the roll with cyclic input until you have loaded the main rotor. This is accomplished by gently bringing the cyclic aft. When the rotor is loaded the pilot can then use cyclic to counter the roll. In the case of a low time pilot the survival instinct may be stronger than his knowledge base and he moves the stick to the left and causes flapping which results in mast bumping/rotor incursion. If my contention of the 18-degree offset were correct then this would further exacerbate the problem by increasing the roll rate with the same results with the low time pilot. An experienced pilot could go with the roll after regaining control of the rotor and maneuver out of the roll into stable forward flight.