JD-Slow-Thumbs, Series Of Helicopter Collectives

Introduction:

I like flight simulators in general,

and having some involvement with helicopters at a company that I work for,

I decided to look for collectives available for purchase on the internet,

and I what I found had a price-point starting at about $500 with fancier ones at about $1,200

so I decided to develop my own invention.

Having worked as a “Manufacturing Engineering Technician” (Process Engineering) in my recent past, I wanted to develop something that could be produced with COTS (commercial-off-the-shelf) material and needing a minimum of tools and a minimum of processing steps.

Over about a year I developed a series of collectives, the first four versions in this series make good Do-It-Yourself projects, while the fifth version would make a good KIT that would be complete enough to work nicely once assembled. This fifth version would also make a good platform for expansion, and very good for “kit-bashing”.

Thanks for reading

JD

P.S. For this series of collectives, I figured out some requirements for the chair that I would need. Since I already had some woodworking tools, I chose a wooden chair as opposed to metal or plastic. Also I wanted a chair with straight sides as opposed to wide front and narrow back. I also looked for a chair that I could attach a joystick / cyclic to. The chair that met all of these requirements was a dining set chair found at a Salvation Army thrift store. (I planned on putting lots of holes in in, it was a platform for experiments)

P.P.S. Many/most collectives, especially American influenced, include the starter, throttle, and governor-increase/decrease. In a simple flight from Point-A to Point-B, you would typically start the engine just once, and then idle (throttle) for a little while, then increase throttle to full power (where a modern governor takes over rpm vs torque vs throttle), and manually increasing and decreasing the governor might be unnecessary in current helicopters. If you believe this, then functions like starter and throttle become perfect candidates for about four mouse clicks per flight. Leaving the actual collective, as the item that gets used the most during flight. With this in mind, my first three versions feature a simple wooden stick for the collective. (I chose a piece of 1”x2”x24” oak). In version-four I switched to PVC and included a starter and throttle and governor.

(P.P.P.S. Later I figured out a method of making a “twist-throttle” which became my version-five which will be in a new and separate thread).

V1 – Rodger Dodger Style using plywood,

Collective lever attached to a vertically mounted joystick,

using PVC plumbing pipe, good idea, very good idea,

but I prefer to work with wood.

Rodger-Dodgers way http://www.rogerdodger.net/diyflightsims/helicopter-simulator/f331_helicopter_collective/

V2 – Stripped down joystick with 15 degree mount,

I found that I had so much Velcro in my first attempt (v1), that the joystick kept coming loose from the mounting base. So I opened up my joystick to see if the internal shaft could be used without the external handle. My second joystick, a LogiTech_Extreme_3D_Pro, was better for modifying. It had a slotted grove in the shaft for the wires to travel through from the top-handle to the bottom-base. Also the gimbal for the potentiometers had four mounting feet that mounted at the same flat level.

In my reading on the internet (must be true), I learned that the angle-movement of most collectives is approximately 30°. Rather than having my joystick pot go from 0°_to_30° I decided to split it into -15°_to_+15° so I added a 15° slope to the vertical joystick mount.

(I also noticed that this LogiTech X3D had less Range-Of-Movement than my other joystick. Much later I would recognize that a ~30°ROM_Joystick_Potentiometer was a much better match to a ~30°ROM_Collective than a ~50°ROM_Joystick_Potentiometer).

V3 – Sliding Potentiometer with wooden handle,

includes hard stops for lever travel, foot-pounds versus potentiometer.

At work I saw an application using a linear sliding potentiometer, at first I did not see much use for it, soon I found a variety of sizes at the local electronics supply store and I started experimenting with a 4inch long sliding pot. (30° is such a magic number, if you go out 8inches on the collective and move it 30° you get 4inches of travel on the linear_sliding_pot. Back up a quarter of an inch and you do not exceed (break) the 4inch limit of the pot).

Also to prevent breaking of the pot I added mechanical hard stops to limit both the lower vertical and upper vertical travel of the collective. If for example, you find yourself descending into a tree and you pull up hard on the collective with even 10 pounds of force, on a 2 foot long collective, this becomes 20 foot-pounds of torque that gets applied to a pot designed for just finger pressure. That little pot needs a little protection.

In my setup, the body of the sliding-pot moves while the center-tap is held fixed. The body of the sliding-pot is glued to a carrier that is attached to the collective lever.

V4 – 3/4inch PVC Cantex Access Box - Starter-button, Governor+/-, throttle-knob.

In my research / scavenger-hunting-for-parts I found an electrical box for push-buttons and toggle-switches that had a good “feel”. It was a “conduit-access-box” from “CANTEX” brand of conduit fittings with many items available at HomeDepot. The best fittings ended up being online-order items available at “ZORO” distributor.

This version features the following parts:

A – PVC, conduit-body, Access-Fitting, Type-E, 3/4inch,

https://www.zoro.com/cantex-conduit-outlet-body-pvc-e-5133152/i/G3499867/

B – PVC, 3/4inch, pipe, gray-conduit or white-plumbing,

at HomeDepot

C – PVC, Electrical-box, Type FSE, 1-Gang, 3/4inch,

https://www.zoro.com/cantex-weatherproof-box-1gang-34-in-hub-pvc-5133364/i/G1372987/?q=5133364

D – Weatherproof cover, PVC, 1-gang,

https://www.zoro.com/cantex-weatherproof-cover-horizontal-pvc-5133362/i/G2801775/

(1/2inch size also works and also has a good “feel”).

E – Starter push-button, simple momentary-on (normally-off),

F – Throttle, simple 300° pot with striped knob,

G – Governor, three position toggle switch, MomentaryOn-Off-MomentaryOn.

left = pot for throttle / center switch = governor / right = push-button for starter