Tip: Modifying throttle stick for mechanical brake
06-04-2012 | 09:02 AM
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From: Linkoping, SWEDEN
Tip: Modifying throttle stick for mechanical brake
When I started flying electric some years ago I felt it would be practical to have a mechanical feedback on the throttle stick at the point where the brake is activated. I figured out a way to modify the stick so that I could get this feedback and in a way where both the point of engagement as well as the strength is adjustable. I think it’s a neat little mod that provides good control over the braking. I recently explained on the Swedish F3A forum how to do this and I thought I would explain it here as well.
The trick is to reuse the spring mechanism that on many transmitters are installed by default at delivery, but to modify it so that it only engages at the lower end of throttle movement where the brake is activated. Below are some pictures on how I made this on my latest transmitter. The spring loaded lever arm that provides the stick centering looks like this.
It rests on two pins on the stick gimbal, which provides the centering force. What one must do is to provide the lever arm with an adjusting screw with which to mechanically lift it from the two pins. On this particular transmitter (Graupner MC-32) this is already done and is used do disengage the centering mechanism on the throttle stick. This adjustment screw is now set so that contact occurs at the position where the brake should be activated. The front pin on the gimbal must then be disengaged in order to only get the mechanical feedback at the lower end. Either just pull out the front pin, or modify the plastic lever arm accordingly to the dashed line above. The result installed in the transmitter looks like this.
With the two marked screws the point of engagement, as well as mechanical resistance can be adjusted to personal preference. I typically have it adjusted so that it barely is felt in addition to the friction that is already set on the brake spring/ratchet. It is all that is needed. The fingers are very sensitive and with too much spring load I find it becomes uncomfortable.
This mod was extremely simple to do on the MC-32, but I believe it can be made on any transmitter. Below are some pictures on how I made it on my old MC-24 which uses standard JR stick assemblies. I believe those are the same on many of the JR transmitters.
First an M2 screw is installed in the stick assembly. The front pin that lifts the spring arm is also removed.
Then the spring loaded arm is drilled and tapped for the small adjustment screw which is used to set the point of engagement.
Slightly more work on these stick assemblies, but still not very complicated. The mod is also reversible in case one would not like it. I hope it can be useful for someone.
/David Lundstrom
The trick is to reuse the spring mechanism that on many transmitters are installed by default at delivery, but to modify it so that it only engages at the lower end of throttle movement where the brake is activated. Below are some pictures on how I made this on my latest transmitter. The spring loaded lever arm that provides the stick centering looks like this.
It rests on two pins on the stick gimbal, which provides the centering force. What one must do is to provide the lever arm with an adjusting screw with which to mechanically lift it from the two pins. On this particular transmitter (Graupner MC-32) this is already done and is used do disengage the centering mechanism on the throttle stick. This adjustment screw is now set so that contact occurs at the position where the brake should be activated. The front pin on the gimbal must then be disengaged in order to only get the mechanical feedback at the lower end. Either just pull out the front pin, or modify the plastic lever arm accordingly to the dashed line above. The result installed in the transmitter looks like this.
With the two marked screws the point of engagement, as well as mechanical resistance can be adjusted to personal preference. I typically have it adjusted so that it barely is felt in addition to the friction that is already set on the brake spring/ratchet. It is all that is needed. The fingers are very sensitive and with too much spring load I find it becomes uncomfortable.
This mod was extremely simple to do on the MC-32, but I believe it can be made on any transmitter. Below are some pictures on how I made it on my old MC-24 which uses standard JR stick assemblies. I believe those are the same on many of the JR transmitters.
First an M2 screw is installed in the stick assembly. The front pin that lifts the spring arm is also removed.
Then the spring loaded arm is drilled and tapped for the small adjustment screw which is used to set the point of engagement.
Slightly more work on these stick assemblies, but still not very complicated. The mod is also reversible in case one would not like it. I hope it can be useful for someone.
/David Lundstrom
