Throttle Detents

[Avro748]

This one has me stumped, here's a bit of background info:

Although the HS748 does not have a reverse system, it does have a "ground fine" flat pitch system, which brings the props to 0º, allowing for quite a bit of drag on landing, as well as less drag if you try to start on a particularly cold day or you're just having trouble getting the engines going. Nevertheless, putting the engines into flat pitch mode is done in much the same way as engaging reverse pitch (bringing the throttles below idle).

My issue is that I don't know how to put a "detent" at the idle position to prevent myself from accidentally engaging flat pitch in flight. I can't seem to find any info on how to implement one either. Any ideas?

Thanks

[Shawn]

I have used a small ball bearing and a spring that engages into a shallow hole to build a detent when making machine tools. I'm not sure how you need to implement the detent or how much room but the bearing and spring is a pretty standard method.

[Avro748]

My design isn't the most space efficient, but I'll look into your method and report back. I have quite a few springs, after all.

Thanks.

[fordgt40]

Not aware of your physical layout/constraints. However, I used rare earth Neodymium magnets to get a detent on my 737 speed brake lever.

[Avro748]

See my previous thread "Throttles" for a photo of my layout. The design is temporary and very "homemade" looking, to put it diplomatically. Could you show me pictures or a diagram of you magnet setup?

Thanks

[fordgt40]

Sorry, but I cannot get a worthwhile picture of this. Looking at your throttle, what I did was to fix a magnet to the inside of the throttle lever (in the correct detent position) then another magnet on the framing to the inside of the lever. You will need to experiment on the correct sizes but the magnets are cheap. Just make certain that the magnets are the correct way around to "attract" and keep a small gap between them as they lock together very well if touching

[Westozy]

The way Shawn described is exactly the same method I use and would suggest!
Cheers Gwyn

[fordgt40]

Fully agree and it was the way I originally intended to go. However, it would have required dismantling the throttle again. Hence a simple solution, albeit not as good