Modify existing yoke by moving the mounting point of the pitch axis centering springs via motor operated by 2 hardware buttons to simulate trimming (moving back and forth the neutral resting position of the yoke).
No electronics, no software, no data exchange with the sim, no roll axis FFB, no vibrations, no special effects.
Just the proper elevator trim.
Full story:
I’m a real world PPL(A) pilot using VR and Honeycomb Alpha yoke for simming and I really miss the real airplane elevator trimming behaviour - you set the pitch attitude/airspeed by applying the pressure on the yoke, then you trim by feel just to cancel the force, and the yoke stays in the new neutral position.
I’m not good enough at DIY to build full dual axis motor/electronics controlled FFB yoke and the Brunner yoke is too expensive for me.
What would you think about modifying the existing regular spring/bungee ropes based yoke (like Honeycomb Alpha) by adding a motor driven mechanism moving only the mounting point of the pitch centering springs versus the yoke enclosure. Without any software or electronics, without any communication with the sim, the motor could be just steered by two hardware trim buttons to move the neutral point back and forth. I can even imagine fully mechanical trim wheel, without a motor. The original potentiometers/sensors in the yoke should remain unchanged.
The operation:
I want to pitch up.
I pull on the yoke to set the desired pitch attitude. I must keep applying the force to prevent the yoke returning to the neutral position.
I operate the hardware trim up button.
The mounting point of the pitch axis centering spring moves towards me.
At some point the forces applied by me to the yoke will dissapear, the springs mounting point will be now closer to me, the forces on the springs will disappear, the yoke will find the new neutral position.
The drawbacks:
No trim indication in the cockpit. But in real world I never look at the trim indicator, I trim by feel only. The only exception - the initial trim setting before the takeoff. But this could be achieved by marking the neutral takeoff trim position on the physical yoke shaft and centering with the hardware switches.
No roll axis FFB, no vibrations due to engine or turbulence, no representation of aerodynamic forces changing with airspeed.
The risk of potentially destroying the Honeycomb Alpha yoke.
The benefits:
The easiest imaginable way to represent the elevator trim behaviour. We should fly by applying the pressures on the yoke and then cancelling the forces with trim. We should not fly (as we often do in the sim) by operating the trim buttons as the primary elevator controls.
I would be happy to hear your opinions or even better to find a partner in pursuing this challenge.
I think this would be a great idea. One of the problems I have with GA flying is adjusting vertical trim. I know the theory and how to do it and use a trim wheel controller; however, getting the trim just right without force feedback is really tough.
Honeycomb Alpha yoke pitch bungee cord design is pretty tight, it may be difficult to move the cord mounts mechanically or to manipulate the tension in some way to move the neutral position back/forth
I was thinking about installing much longer bungee cord, moving its ends through drilled holes outside the yoke enclosure and installing some manual mechanical wheel on which the bungee should be coiled. By turning such wheel (like a trim wheel in the GA plane) the neutral position of the yoke would move back and forth. But this would require 2 such wheels synchronized on in front and one in the back of the enclosure (outside the enclosure). This would be required to have the same tension for pulling and pushing. Hard to figure out the way to synchronize both wheels.
The bungee cord would also like to unwind…
As a pilot IRL as well, I always had the same frustration about the trim, as the feel of “relieving an effort” when trimming is essential, and good trimming is an important part of the proper piloting of an aircraft. Force feedback in general is great, but less important IMO. So, as I was going to build the yoke for my home cockpit, I came up with the same solution.
In my case it’s built 100% from scratch, using an Arduino, 3D printing, and various hardware parts for bearings etc. It has an actual wheel to control the trim, and even a display of the current position.
And I’m pretty happy with it ! The main drawback is that the force is not dependent on the actual speed of the aircraft, so for example you don’t feel how it should become “lousy” at low speeds, but one can live with it. And anyway it’s still so much better than “fake” trim where you need to move the yoke to the center position while trimming which is very unrealistic and especially bad if you use your simulator to maintain real world abilities.
The most “difficult” part is to find a good way to build the tension, I tried many things and finally replaced the rubber bands with springs, that are a bit too strong but I’ll eventually find one that fits well.
Impressive.
Where is the motor which moves the neutral position?
Aha…
The motor is driving the rotating screw which moves the point of bungee attachment - simple and clever.
It’s a pity that no yoke manufacturer produces a yoke with mechanical or simple motor driven trim
Probably because non-pilots are not used to the real world trim operation and no sim directly supports external mechanical trimming (trim controls will not move in the sim, unless some very clever programming would be applied).
As the first test I went to the extreme. To avoid the unrealistic always-return-to-the-same-neutral-position of spring/bungee cord loaded yokes, I disconnected the pitch bungee altogether.
So now I can fly more like the real life, by operating the elevator via yoke inputs without the need for the unrealistic apply-the-trim-and-smulataneously-go-back-with-the-yoke-to-always-the-same-neutral-position.
I know this is unrealistic in the other way (very weak forces on the elevator control) but I will see how it works in the sim. I would expect issues with applying backward pressure during a turn and the releasing it for straight-and-level.
But I expect it to be better versus the common wrong behaviour of sim pilots of controlling the elevator via trim inputs instead of yoke movements. Trim should be only used to cancel the forces on the yoke, not for actually controlling the plane.
There is still some resistance (I will consider how to increase it) on the pitch axis due to mechanical drag inside the yoke mechanism. To have bit better balancing of pitch and roll axis I replaced the roll bungee with a much weaker rubber band.
So far I’m rather happy with this mod (no pitch centering spring, very gentle roll centering spring).
First impression:
Pros:
The yoke no longer fights against me! Suddenly it became precise control instrument.
I can keep the yoke neutral for any airspeed, desired pitch angle.
I can apply precise pitch changes, minimal control inputs and keep them easily.
I can fly level despite power changes.
I can flare and touch down like never before.
Neither pros nor cons:
It requires very gentle touch. I remember my first flight lessons in not so perfect weather - I was literally squeezing the juice from the left yoke handle, next day my left hand muscle ached. My instructor spotted this and asked to keep the yoke with just two fingers - there are not so big forces required in small GA plane, unless the weather is really severe.
It requires constant observation of the horizon to keep the plane level or at the desired pitch angle for climb or descent. But this is also what we do in the real VFR flight. When simming I prefer to be as involved as possible, I always fly manually, so I actually like this behavior.
Cons:
There is no trim applicable altogether. No forces perceived. The yoke stays in any position I want it. I can’t trim by feel. I can apply trim artificially, and then move the yoke accordingly, but this has nothing in common with the realism. On the other hand, the default simulator trim behavior is plainly wrong - when applying the trim, the yoke should remain in position, only the forces should disappear. In the sim with unmodified sping-loaded yoke you must move it to it’s mechanical neutral position while trimming which is just wrong!
Aircraft should be controlled by applying pressures to the controls not by moving the controls. When you apply the pressure the control (yoke) moves, but your muscle memory should be trained for pressures not movements. With no spring on the pitch axis, I’m actually controlling the plane by moving the controls, as without the spring there are no control pressures.
To stay level during the turn I can’t just apply back pressure and release it when the turn ends. I have to control the straight and level more visually than kinetically, by observing the horizon line position vs. the cowling. But unless you have advanced moving platform, the whole simming experience is visual, lacking the flying-by-the-seat-of-your-pants experience.
For now I’m happy with this super simple 5 min. mod and my new collaborative, precise yoke. But I will still think if/how the yoke could be modified for the movable neutral pitch position.
I’m not sure if modifying the honeycomb alpha would be more benefiutal to your time, or your money to modify what exists in the honeycomb alpha to a system like that or if a DIY approach is better suited… either way, modifying the HCA to have a new system, or creating a FFB yoke is going to involve some DIY mechanics unless someone here already has the design files.
Either way you go, will love to be informed on how it goes!
As for now I have high hopes that installation of the small linear actuator (see links in my post above) and following more or less the idea of @EconomyArc31614 (see his design a couple of posts above) will result in Honeycomb Alpha yoke mod which will be working and will be also reversible (probably I will need to cut a hole in the yoke upper cover to have enough space for the actuator but also to have easy service access; I will need to arrange some box cover to put it over the hole/assembly).
My experiment with no pitch bungee at all, resulted in discovery that I actually prefer way smaller forces compared to original bungee cords. Also the actuator will always work with the force, never against it, only to release the pressure (this is what trimming is about). This will allow using relatively weak and small linear actuators and not necessarily super sturdy construction.
I will report at the end of October, when the parts will arrive.
For now I’m going to experiment with a prototype based on Fischer Technik construction set (similar to Lego Technic). It allows moving the mechanical neutral
(no back/forward pressures/forces on the yoke handle) position if the yoke, according to different airspeed/trim setting. The video of the prototype below:
I found this video (link below). The modder was not pursuing the same goal but the video shows the interior of the yoke handle, this will be required for my mod as I will need to rewire the trim switch, to control my elevator trim linear actuator:
stepper motor linear actuator with 55 mm stroke (a bit to short for Honeycomb Alpha, which has about 85 mm stroke)
stepper motor linear actuator with 80 mm stroke (with a weaker motor and a bit too much overall length for the Honeycomb Alpha - it may limit the travel of the yoke by a couple of mm).
Prototype 2.0 is presented on the movie - unfortunately I was missing my third hand to demonstrate the trimming principle while filming, I needed to use my leg to apply control pressures to the yoke Both actuators are mounted for test purposes, on the movie I’m testing the longer actuator.
The rubber bands for the pitch axis will be relatively easy to install (will be anchored under the yoke’s cover). Probably I will need to cut a hole in the cover to allow actuators fitting in.
So far the cost of the parts:
stepper motor controller,
linear actuator,
two position switch (not yet shown on the movie) allowing switching the left elevator trim switch on the yoke handle from working with the Honeycomb electronics inside the yoke to control the stepper motor,
9V power supply,
rubber bands,
two end microswitches to limit the movement range of the actuator,
some wires and connectors.
is at about 50 euro.
The only permanent modification to Honeycomb Alpha yoke will be:
hole in the upper cover allowing mounting the actuator,
two small holes at the back of the yoke for power plug and the speed potentiometer of the stepper motor controller,
switch in the yoke handle (barely visible at the back of the handle)
one small hole in the handle and another in the yoke’s front panel for a control wires.
Parts from AliExpress arrived in 16 days. Prototype v. 3.0 which I hope will be close to the final version.
The actuator fits into the case but is a little too weak, so instead of running it at the rated 9V, I use 12V. Even with 12V it’s still on the weak side, so if I start trimming for bigger forces (bigger yoke pitch pressures/deflections) the mechanism may refuse to move. Just in case it will overheat and be destroyed, I ordered two from AliExpress. They are cheap.
I have also a stronger actuator, but it has two disadvantages:
it’s a bit higher and may not fit into the case,
it has smaller stroke (5.5 cm, versus 9 cm of the on I’m using now), smaller than the stroke of the Honeycomb Alpha (which is about 8.5 cm).
If my current actuator will quit at 12V, I will then experiment with the stronger, higher, shorter one.
I just completed the first flight test in the Comanche. It was worth the effort! Flying is much more like a real world (I’m a PPL(A) SEP(L) pilot)!
Pros:
trimming is now an act of feel, I just apply the control pressure and then use the trim by feel, until I no longer feel the pressure (previously it was and act of thinking - so much trim added, so much movement of the yoke to the neutral position),
yoke position now corresponds to speed, which triggers muscle memory and visual cues,
I can hear and feel (slight vibration from the stepper motor) the trim working,
in general - wow, so much more like in the real life!
Cons:
trim indicator in the cockpit is not moving, I can judge initial takeoff trim setting by the yoke position (when airborne it doesn’t matter, I trim purely by feel),
the mod will probably interfere with autopilots which may expect the yoke in the general spring-loaded neutral position, however both in real life and in the sim I fly manually only,
some people noted that the trim behavior I’m looking for is characteristic for small GA planes only, according to them, the hydraulic systems (or fly by wire systems) in airliners actually keep the yoke in always-the-same neutral position. But in both real-life and in the sim I fly small GA planes only.
Additional hint: As there is no permanent neutral/zero position of the yoke pitch axis, the yoke response should be linear, so any response curve defined in the controls setting in the sim or in the external tools (I use Axis and Ohs) should be removed.
Both actuators are mounted for test purposes, on the movie I’m testing the longer actuator.
