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ROTAX 912UL/912ULS Frequently Asked Questions

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John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Mar 14, 2013 6:07 am Post subject: ROTAX 912UL/912ULS Frequently Asked Questions

Hi Kolbers:



This info from the ROAN, ROTAX Owner Assistance Network:



http://www.rotax-owner.com/pdf/ROAN%20FAQs.pdf



Answers some good questions, especially "What speed to operate our 912's?"



john h

mkIII

Titus, Alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

frank goodnight

Joined: 27 Dec 2011
Posts: 126

Posted: Thu Mar 14, 2013 6:52 am Post subject: ROTAX 912UL/912ULS Frequently Asked Questions

Very interesting, especialy the Rpm . I have been running my 912uls

at 4800 RPM and taking off at 5000 didn't know 5500 and 5800 was better for the engine . Thanks John. 

Frank

From: John Hauck <jhauck(at)elmore.rr.com>

To: kolb-list(at)matronics.com

Sent: Thu, March 14, 2013 9:07:35 AM

Subject: ROTAX 912UL/912ULS Frequently Asked Questions

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John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Mar 14, 2013 8:26 am Post subject: ROTAX 912UL/912ULS Frequently Asked Questions

 

Very interesting, especialy the Rpm . I have been running my 912uls



at 4800 RPM and taking off at 5000 didn't know 5500 and 5800 was better for the engine . Thanks John. 



Frank

 	  Quote: 	
		     In my opinion, lugging a two or four stroke is not good for them.  They are designed to turn high rpm. I have always used 5,000 rpm for normal cruise.  If I get in a hurry, I fly 5,200 and 5,400 rpm.  Whatever is comfortable for me and the airplane. I flew 5,400 rpm from Alabama to OSH and back in 1994, with my 912UL.  That was right after I got home from flying 232 hours on the first Alaska flight.  Only difference was fuel burn and a little more cruise speed. john h 	
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  [quote][b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

undoctor

Joined: 21 Oct 2008
Posts: 212
Location: Bethelhem, PA

Posted: Thu Mar 14, 2013 12:10 pm Post subject: ROTAX 912UL/912ULS Frequently Asked Questions

John,  will you please re-post the link for the FAQ?  I lost it     somewhere in my computer.

     

     Thanks,

     

     Dave Kulp  

     

     Do Not Archive

     

     On 3/14/2013 10:52 AM, frank goodnight       wrote:

     

     [quote]                       Very interesting, especialy the Rpm . I have been running           my 912uls

         at 4800 RPM and taking off at 5000 didn't know 5500 and           5800 was better for the engine . Thanks John. 

         Frank

                          From:               John Hauck <jhauck(at)elmore.rr.com> (jhauck(at)elmore.rr.com)

               To:               kolb-list(at)matronics.com (kolb-list(at)matronics.com)

               Sent: Thu,               March 14, 2013 9:07:35 AM

               Subject:               ROTAX 912UL/912ULS Frequently Asked Questions

             

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     [b]

pipercolt

Joined: 08 Jan 2012
Posts: 46
Location: Randolph New York

Posted: Thu Mar 14, 2013 2:59 pm Post subject: Re: ROTAX 912UL/912ULS Frequently Asked Questions

Hey John

Is there a similar list for other Rotax engines, like the 582?

Thanks

Bob

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Mar 14, 2013 4:16 pm Post subject: ROTAX 912UL/912ULS Frequently Asked Questions

John,  will you please re-post the link for the FAQ?  I lost it somewhere in my computer.



Thanks,



Dave Kulp  

 

 

 

If you lose it again, Google "ROAN ROTAX FAQ".

 

http://www.rotax-owner.com/pdf/ROAN%20FAQs.pdf

 

john h

mkIII

Titus, Alabama[quote] [b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Thu Mar 14, 2013 4:34 pm Post subject: ROTAX 912UL/912ULS Frequently Asked Questions

I don't know about the 582.  I found this one by accident.



A search of the ROAN site should turn up some results.



john h

mkIII

Titus, Alabama



 




Hey John

Is there a similar list for other Rotax engines, like the 582?

Thanks

Bob

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Thumper

Joined: 24 Aug 2008
Posts: 46
Location: Oakland TN.

Posted: Fri Mar 15, 2013 7:30 am Post subject: Re: ROTAX 912UL/912ULS Frequently Asked Questions

FYI.  The RPM number is used for take off.  What two different Rotax forum guys said is: the takeoff rpm should not be lower than 5300, which means prop loading should be set to keep the engine higher than 5300 period during takeoff load.  They intended that for those guys running clean airplanes not to prop them for their top speed and forget minimum takeoff RPM's.  After takeoff you can fly at whatever reduced rpm you want without harm.  The Engine was designed to run at cruise of 5500 all day if you want to but it is not a requirement to do so.  Once you reduce throttle you reduce load on the internal engine parts so they are not concerned with that.  It has been a big confusion and people saying you are supposed to cruise at 5500 minimum but that was refuted by Phil Lockwood and the other man at another 912 forum. So just as long as the takeoff full load RPM = 5300 they are OK. The book says 5500 but they both admitted that 5300 was OK with them.  I like that 3800-5000 range myself for cruise, makes a difference in noise and fuel burn change of 1.5GPH.  On those days when I'm flying with my Cub friends, Challenger or Trike buddys I smoke them on fuel burn at equal speeds.  Not a Kolb though, BUT I will have another one when the right deal comes along.  See you at the Homecoming I hope.  Dennis, Aeroprakt A20/Kolb like airplane.

_________________
Dennis Long
Oakland TN
2000 Aeroprakt A20 Vista Cruiser, 2016 A22LS Aeroprakt
Previously Kolb Mark IIIC, 94 Firestar, 84 Ultrastar.
1200+hours since 1/1/2009

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Fri Mar 15, 2013 8:11 am Post subject: ROTAX 912UL/912ULS Frequently Asked Questions

I like that 3800-5000 r!

 ange myself for cruise, makes a difference in noise and fuel burn change of

1. 

Dennis Long

Oakland TN

2000 Aeroprakt A20 Vista Cruiser

Previously Kolb Mark IIIC, 94 Firestar, 84 Ultrastar.

600+hours since 1/1/2009

 

Kolbers:



Been flying 912's on my MKIII for the past 20 years and more than 3,000.0

flight hours.



Seems I have a difficult time maintaining a minimum engine oil temp of 190F

if I don't fly at least 5,000 rpm.  Engine temps drop rapidly below 5,000

rpm.  Besides, with my airplane, in order to cruise at least 80 mph, I need

5,000.



Flying with a ground adjustable prop it is necessary for me to pitch for

best take off and cruise.  To do this, I pitch for 5,500 rpm, wide open

throttle, straight and level flight.  With this pitch setting I get aprx'ly

5,400 rpm during takeoff and climb.



If I flew at sea level all the time I might be able to pull a tiny bit more

pitch.  However, on my flights West, it is necessary to climb to

12,000-13,000 feet ASL, and my flight environment and field elevations are

generally 4,000 to 8,000 feet.  If I can pull 5,400 rpm climbing at

home/near sea level, I'm down to 5,100 to 5,200 rpm out West.   So what I do

is set my pitch for about 5,600 rpm straight and level, wide open throttle

at home.  Then when I get out West I still have respectable performance.



I am a firm believer in freeing up the engines and let them turn as they

were designed.  Overpitching, to me, has the same results of lugging down a

car or truck when they are equipped with a 5 or 6 speed transmission.  It

hammers them to death.

john h

mkIII

Titus, Alabama

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Thumper

Joined: 24 Aug 2008
Posts: 46
Location: Oakland TN.

Posted: Fri Mar 15, 2013 8:35 am Post subject: Re: ROTAX 912UL/912ULS Frequently Asked Questions

Absolutely John. No lugging occurs if the takeoff RPM stays above 5300 per Phil. In flight we can cruise where we want with no harm as long as the prop is not the limiting factor, that would be lugging.  NOW, I see guys with in-flight adjustable props doing just that by loading up the engine at reduced RPM, that is lugging the engine, but it is a habit they learned on high performance GA aircraft and can't seem to explain it to them.  Yours is set up like mine.  If I want to fly slow no harm because the engine isn't lugging.  Same thing on the two strokes although on those if you reduce throttle a lot carbon build up will occurr quickly.  See you at Sun-N-Fun maybe, weather permitting.

_________________
Dennis Long
Oakland TN
2000 Aeroprakt A20 Vista Cruiser, 2016 A22LS Aeroprakt
Previously Kolb Mark IIIC, 94 Firestar, 84 Ultrastar.
1200+hours since 1/1/2009

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