Rudder Boost Tab
Photos, John Thompson

Primary Rudder Servo, 1 x HiTec 5945mg Digital
Primary Elevators Servos. 1 x JR-8411 Digital per elevator half.
Boost Tab Servo, HiTec HS-55 Sub Micro. I dont know how well this servo will hold up.
The boost servo is run on its own channel, mixed with the Rudder channel as Master.
I am using a "point" mix so the boost tab is not very active around center.
3-18-01

In this experiment, I replaced an MPX Jumbo. This servo is rated at almost 300oz of torque and weights 6oz. I  replaced it with one of the new HiTec Digital's. The one I chose was the 5945mg. This is a 150+oz standard sized servo that weighs just under 2oz.

The rudder on the Extra is too big to be effective with only 150oz of torque, so I added an active boost tab controlled by a HiTec feather weight servo.

This combination of single standard sized Digital servo augmented with a boost tab, actually seems to outperform the single 300oz MPX servo and also saves a couple oz of weight.

One of the concerns with boost tabs is trimming the plane and getting it to be as precise as with out them.
The simple solution is to power the boost tab of a servo, rather than statically of the fuse.
What this basically does is cause the primary surface to not know its boosted when the surface is at center.
The end result is that you get the boost of the boost tab with out all the normal nasty tendencies of boosted surfaces.

In conclusion, so far I only have two flights on the plane setup this way.

The snaps start and stop just as precisely as before. Knife edge power has improved and so far, I have not noticed any thing negative about the setup.

Overall, I am very pleased with this experiment and look forward to flying it in some better weather.