Difference between revisions of "Elevator trim"
(Created page with "Refactored trim page") |
m |
||
| (5 intermediate revisions by the same user not shown) | |||
| Line 1: | Line 1: | ||
| − | + | 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. | ||
| + | |||
| + | [[File:Servo mount.jpg|1280px|frameless]] | ||
| + | |||
| + | === ECU for trim === | ||
| + | |||
| + | Per @akschu, using the [https://www.rugged-circuits.com/microcontroller-boards/rugged-mega-et 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 | ||
| + | |||
| + | === Notes for handling input === | ||
| + | |||
| + | https://www.arduino.cc/en/pmwiki.php?n=Tutorial/AnalogInput | ||
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