SuperSTOL with Catto Prop

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Augustus
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Location: South of K.C., MO, USA

SuperSTOL with Catto Prop

Post by Augustus »

I am wondering if the minimum RPM for the Rotax engine (with the 2.43:1 gearbox in mind) is the ideal RPM just after touchdown for a SuperSTOL. I'm thinking that it might not be.
This is my thinking and please spank me soundly if you disagree!

My minimum RPM is set at 1,950 (which is what I use for touch down). That means my MONSTER Catto prop is churning @ 802 rpm. That's waaay to fast.

What do you aviators think?
SuperSTOL 332
Ed T.
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kenryan
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Re: SuperSTOL with Catto Prop

Post by kenryan »

Rotax manual says 1400 for minimum idle rpm. Can you set it at that, and use some throttle on start and warm up if necessary?
Super Stol Kit #299
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Augustus
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Re: SuperSTOL with Catto Prop

Post by Augustus »

Ouch Ken. Will check it out. 576 rpm sounds quite a bit better at touchdown.
Still adjusting things after two years. Thanks.
SuperSTOL 332
Ed T.
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kenryan
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Re: SuperSTOL with Catto Prop

Post by kenryan »

I have heard that idling low can be hard on the gearbox. Maybe that only applies on the ground? Would be a good question for the Rotax Forum:

http://www.rotax-owner.com/en/rotax-for ... -questions
Super Stol Kit #299
dkshow
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Re: SuperSTOL with Catto Prop

Post by dkshow »

I can't remember what mine idles at but I'm sure it's more than 1400. I know they don't like to run slow. I think mine idles somewhere near 1750-1800
Keith Showalter
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Anchorage, Alaska Superstol N445K
Built in NC with Rob Pedersen, Plane Fun Aircraft
AV8R Paul
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Re: SuperSTOL with Catto Prop

Post by AV8R Paul »

Mine Rotax idles at 1600 to 1700 RPM just fine.
AV8R Paul
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Augustus
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Re: SuperSTOL with Catto Prop

Post by Augustus »

Thanks for the info folks. Here's an update: In the interim from my original post, I had one of my OEM floats decide to not float. It's a good thing that I did not adjust the idle. It would have resulted in much head scratching about how I just messed up my engine. It was pretty much an easy diagnosis and fix to replace the floats in one of the carbs. Thanks again to Ronnie and South MS Light Aircraft, Inc.
I did reduce my idle to around 1600 RPM and it was EXACTLY what the doctor ordered. I increase the idle up to about 1900 after I land but that few seconds where it is at 1600 makes a big difference -- especially on a hard runway with a downward slope.
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Ed T.
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FlyerChief
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Re: SuperSTOL with Catto Prop

Post by FlyerChief »

Chasing the Perfect Idle Speed

There is a response to the idle speed question on the Rotax Forum...
http://www.rotax-owner.com/en/rotax-blo ... 2-idle-rpm

My 912 uls will idle smoothly as low as 1300 rpm, so I find myself having to adjust it up every flight with the throttle to keep it around 2200 for warm up. Being able to turn the idle down to to 1300 appears to give me smoother shutdowns, but it's way too slow to idle a 912 uls for any length of time.

Dan
When everything seems to be going against you, remember that the airplane takes off against the wind, not with it. ~Henry Ford
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