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Trouble landing your -9?

N941WR

N941WR

Legacy Member
I was just reminded of one of the advantages of running electronic ignition; you can turn the idle way down.

How does this impact your landings? I'll tell you...

I have dual P-mags on my -9 and one day I realized I was having a difficult time slowing the thing down. When I got on the ground I realized I was idling right around 780-800 RPM. A bit high, but nothing bad.

After turning the idle down to around 650 RPM (Remember, with dual electronic ignition you can get a smooth idle, even with a light wood prop.) the plane would slow down very easily, which made it much easier to land.

This may impact the short wing RV's but probably not as much as the -9.
 
600 rpm

I have dual mags, and idle at around 600 rpm. No problems getting down either.

edit: I do run a Sensenich fixed pitch prop, so that probably makes a big difference for a smooth idle (compared to a Catto).
 
Last edited:
N941WR said:
I was just reminded of one of the advantages of running electronic ignition; you can turn the idle way down.

How does this impact your landings? I'll tell you...

I have dual P-mags on my -9 and one day I realized I was having a difficult time slowing the thing down. When I got on the ground I realized I was idling right around 780-800 RPM. A bit high, but nothing bad.

After turning the idle down to around 650 RPM (Remember, with dual electronic ignition you can get a smooth idle, even with a light wood prop.) the plane would slow down very easily, which made it much easier to land.

This may impact the short wing RV's but probably not as much as the -9.
Click to expand...

I agree that idle speed is a factor in landing characteristics of RV-9's (and the other RV models) but I think a bigger impact is whether you have a fixed pitch prop or a constant speed. The fixed pitch props we use on RV's have a lot of pitch because of the wide speed range they have. This high pitch produces a lot of residual thrust at idle. This makes idle speed a bigger factor with a fixed pitch prop compared to a constant speed. With a constant speed prop I don't thing you will notice much of a difference with the E.I unless it is a prop with light weight blades (now I'm thinking...were you changing to a whirlwind?)
 
rvbuilder2002 said:
... With a constant speed prop I don't thing you will notice much of a difference with the E.I unless it is a prop with light weight blades (now I'm thinking...were you changing to a whirlwind?)
Click to expand...

Scott, I was running a 9 pound Catto and am going to move up to an 18 pound ground adjustable Whirlwind. That's why I was running such high RPMs.
 
N941WR said:
Scott, I was running a 9 pound Catto and am going to move up to an 18 pound ground adjustable Whirlwind. That's why I was running such high RPMs.
Click to expand...

Yea, a really light prop is typically tough to get a smooth idle anywhere below about 725 RPM. The fixed pitch metal will go down near 600 rpm and still idle pretty smooth.
 
My 9A with an FP Sensenich can idle on the ground at ~650 rpm. It won't spin that slow while flying faster than 75. Just slow her down to 65 mph indicated (1.3 Vso) then the revs will drop and you'll make the first turnoff everytime.
 
idle comment

ok, I can see the benefit of a low idle. Better approach 'drag'.
Hard to practice forced approaches with the engine still producing thrust too!
But!!!
How the heck would you accurately SET it with that silly little tach with the needle jumping around.
I think if I did hit 600, it would slow down my taxi speed as well, without using so much brake!
...but then again, if I idle below 1000 rpm, the plugs foul!

it's one dang thing after another alright!
 
Pull the mixture out...

flyboy1963 said:
ok, I can see the benefit of a low idle. Better approach 'drag'.
Hard to practice forced approaches with the engine still producing thrust too!
But!!!
How the heck would you accurately SET it with that silly little tach with the needle jumping around.
I think if I did hit 600, it would slow down my taxi speed as well, without using so much brake!
...but then again, if I idle below 1000 rpm, the plugs foul!

it's one dang thing after another alright!
Click to expand...

As far as possible while on the ground. Just this side of shutting off the engine.

Kent
 
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