NMPRA

In EF1, is it OK to use Hitec mini HS 85BB (analog) servos for the Elevator?
JSC.

Jeff,
Yes, these servos are fine. The recommended torque spec by the NMPRA in the rules is 30 oz-in

The Hitec HS-85 has 41 oz-in @ 4.8v.


Randy

The Rules say it's OK. But for $5 more. Why not get a Hitec HS225 MG ?

I was under the impression that the racing rules said for a single servo on a single surface ( like elevator, rudder) you were supposed to use servos with 4 mounting screws, not two. In the case of redundant surfaces or servos, two screw servos were ok.

Are the EF1 rules different with that regard?

Here is what the E-F1 rules state:

From Section C, Pre-flight Inspection of Aircraft
3) Servos controlling the pitch and roll functions shall be of adequate strength for the weight and speed of the aircraft. It is recommended that servos have a minimum torque rating of 30 in/oz. (27 m/kg)
4) Control surfaces shall be firm on the hinge line without excessive play. Safety inspectors shall be alert to the danger of excessive play whenever electronic servo throw reduction is used in combination with a mechanically inefficient linkage.
5) All screws holding the servos to the servo rails or trays and holding any trays to the airframe shall be in place and secure. Rubber grommets shall be used on all servos designed to accept them. If the heads of the servo mounting screws are small enough to pull through the grommets, washers shall be used to prevent this. Alternatively, servos may be permanently installed with glue.


Randy

Thanks, Randy!