Difference between revisions of "Elevator trim"
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| − | + | This page describes planned changes and progress to the elevator trim system. | |
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| + | == Change To Electric Trim == | ||
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| + | The Bearhawk uses a cable-operated trim system that actuates full-servoing trim tabs on each elevator. In my experience, the system is overly sensitive and awkward to use. I will never understand why the designer didn't opt for a flying tail type trim like a Skywagon or Super Cub. | ||
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| + | In coordination with a fellow builder, I've opted to change to an electric trim that actuates the same trim tabs, but non-servoing. This changes to feel to something more like a standard 172. It adds an electric trim servo to each elevator. | ||
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| + | A simple bracket to which to mount the electric trim servo on the underside of the elevator. Composite blister style fairing will cover the recessed servo. A push rod will emerge through a slot in the fairing and attach to the control horn on the trim tab. | ||
[[File:Servo mount.jpg|1280px|frameless]] | [[File:Servo mount.jpg|1280px|frameless]] | ||
Latest revision as of 06:30, 22 May 2024
This page describes planned changes and progress to the elevator trim system.
Change To Electric Trim
The Bearhawk uses a cable-operated trim system that actuates full-servoing trim tabs on each elevator. In my experience, the system is overly sensitive and awkward to use. I will never understand why the designer didn't opt for a flying tail type trim like a Skywagon or Super Cub.
In coordination with a fellow builder, I've opted to change to an electric trim that actuates the same trim tabs, but non-servoing. This changes to feel to something more like a standard 172. It adds an electric trim servo to each elevator.
A simple bracket to which to mount the electric trim servo on the underside of the elevator. Composite blister style fairing will cover the recessed servo. A push rod will emerge through a slot in the fairing and attach to the control horn on the trim tab.
ECU for trim
Per @akschu, using the Rugged MEGA-ET. This is an extended temp range model with better more rugged specs than the Arduino equivalent.
Bristol SG servo integrated position sensor can be read by its I/O pins.
For driving the servo motors with the MEGA, a motor driver sub board is required: https://www.pololu.com/product/2519