28. October 2015 by Peter
Another thing that I have been spending time on the last month is my attempt to build my own throttle. It all started over 2 years ago when I all of a sudden juggled the jigsaw and ended up with the 11 plates for a DIY TQ. And so they have been laying around untouched for over two years…
But now things are moving! And moving rather fast.
So I have used August and September on the throttle handles and they have come out quite okay. The video below shows what I have done.
A special thanks goes out to Sven-Erik Arneberg who have been a huge inspiration for the motorization of the throttle levers. He has also helped me interfacing the servos with Prosim737. The link is to the facebook-group “Simgruppa” a cockpit building site. If you now are a member yet, you should head over there right now. You can get a lot of help from this group and fast.
So there are a few things that I have done in my build that might be of inspiration to you:
The reverser handles have been fitted with small 10k pots instead of microswitches. This allows for the reverse thrust to be applied according to the position of the handle and not just more/less depending on whigs microswitch is engaged. You could say: the handle has has a function in all its movement.
I was lucky enough to try a real B737 throttle a few weeks ago. And there is a huge difference between what I am making and the realthing.The reverser handle is locked unless the throttle is in idle. Then you move the reverser handle halv way up to arm the reverser and only from half way and up is where you apply the reverse thrust. Furthermore I have installed rubberbands on my handles so they return to idle. On the real thing the reverser handles keeps their position.
In order to apply pressure on the handle it self – to make it a bit harder to move I have used the kind of fabric that you put under your furniture to prevent it from scratching the floor. The grey fabric that I use is from IKEA. So the idea is that the handle is so tight on the axis that it presses a bit on to the fabric creating a sort of resistance when the handle is moved.
I use 10K sliding potentiometers to measure the position of the throttle handle. This is easily done by connecting the handle to the pot via an arm. This way I do not have to install gears and the resolution will be better because of a longer travel with the slide pot compared to the normal turning potentiometer. These were the longest I could find. To get the correct length of travel you need to adjust the position of the arm om the throttle handle.
Inspired by Sven-Erik Arnsberg I have attached heavy duty servos to throttle arms If this works it will allow for Prosim to move the handles when the A/T (Auto throttle) is engaged in a mode. That is what you call a motorized throttle. 🙂 The servo also gives a nice feel the the handles when moving them with no power on the servo. You need to adjust the position of the horisontal arm to get the right movement of the arm compared to the travel of the servo-arm. it takes a few try before you get it right (Hence all the holes in all three pieces.
The Fuel cutoff is pretty strait forward. However I have placed the microswitches so that the switch only is engaged when the handle is released / locked. You cen see in the video how this is done.