Subject: [FlyRotary] idle speeds

 

Last week we had some discussion on idle speeds, and I think the consensus

was to keep it around 2000 or a little under. Just for information for other

canard pusher people, I think 2000 is going to be a real problem for me. At

the current 1850 setting with the big 3 66/84 prop I have on she's pushing

hard against the brakes. I think I could taxi the length of the runway at

idle and be doing 30/40 kts at the end. On a short (3400) runway the only

way to stop might be kill the engine once on the ground, or even on short

final. So I need to get the idle speed way down.

John Slade (more power than I know what to do with)

 

John;

 

Yeah, I’d think we’d like to get the prop down to 700 or less. I’ll have a 3 66/85 on my Velocity. If your engine will run nicely at a lower speed - great.  I found that on the dyno my 20B would do fine to 1500; below that we had some tuning problems with rich mixture. That was before installing MAP referenced pressure regulator and some EC2 tweaking to reduce the flow of the 570 cc/min primary injectors to closer match the 500 cc/min secondary.  I’m hoping for a nice idle around 1200.

 

The low speed operation likely depends on your induction system design, and where the injectors are located.  I have primary in the housings and secondary about 13” upstream.