BANDIT RUDDER
A Bandit with a standard fin experienced a severe rudder flutter as a result of servo gear failure and the unfortunate result was a crashed model. This is the first time that this has occurred in 4 years and thousands of Bandit flights that we are aware of. Since the standard fin has a larger rudder than the swept fin it would follow that it would be more prone to a flutter problem. Flutter can occur if there is any spring in the control system. This dictates that the servo be very tightly screwed to the mounting rails and that the mounting rails be very securely glued to the internal fin structure.

By switching to a metal gear servo, we also can remove a possible weak link in the system. Worn nylon gears can also be a spring source. We have been using JR 3321 servos for the rudder but these servos do not feature metal gears and currently there are no plans to change it.

We just received a sample 94141 servo from Airtronics that comes with a JR compatible plug. This is a high torque precision unit with a metal gear train and a uniquely variable mounting system. It looks like a great candidate for operating some control surfaces (like the Bandit rudder) on jets. See your Airtronics dealer.

Another consideration: If a control surface gets a hard rap from accidental handling as can happen in transport or just sitting in the pit area, nylon gear trains could be damaged. If undetected, this damage could show up in flight. If there is some concern in this area it is worth the time to change the servo before flight and have it checked out later.