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Prop settings

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redrocketrider

Joined: 13 May 2011
Posts: 67
Location: Nervino airport

Posted: Fri May 27, 2011 6:44 am Post subject: Prop settings

Hello Kitfox flyers, we are  seeking info and opinions on what pitch you set your GSC three blade props(912)  for most all around use. Thanks to all for your help. Toodie and  Bob

   [quote][b]

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_________________
Keep the dirty side down/Blue skies. Bob

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Fri May 27, 2011 12:55 pm Post subject: Re: Prop settings

Hi Toodie and Bob,



There is no hard and fast answer for a pitch, for each aircraft has it's own drag and flight characteristics. But there is a very easy way to arrive at an answer for any plane and any prop. If someone has the same type plane and same prop they can get you close, but you may still need to dial it in for your plane. You need to balance your climb, cruise and fuel with this ground adjustable prop and you don't usually want it to be too far set for climb (flatter pitch) or too much toward cruise (courser pitch). Going either way too far defeats your best all around performance. The Rotax was built and has a specific range of rpms to run within. You need to set the prop to a pitch to achieve 5500-5550 RPM at wide open throttle (WOT). When you set the prop to get this rpm everything else in the middle will take care of itself. You are better off to cruise at 5000-5300 rpm after your prop is pitched at 5500. This setting for a fground adjustable prop will give you the best all around performance for climb, cruise and fuel economy. (While I'm thinking about it set the idle rpm to 1700-1800) 

Now how to get your prop setup. Tie the plane down. You want enough pitch in your prop to get close to a 5100-5200 static run at WOT. Once you have the static done that only gets you in the ballpark it's time to test fly it and check for rpm and this is where you can get a real pitch number for your individual plane. Each brand of plane and each home built can and will be a little different in prop pitch to achieve the same WOT rpm. So as you test fly your plane run it up to WOT for about 30-45 seconds. See if you are in that 5500-5550 rpm area. A couple rpm either way is no big deal. If your engine rpm tops out at lets say 5400 rpm at WOT then remove another 1/2 degree from the pitch to flatten it a tad more. If you are running 5600 then add about 1/2 degree. That is all there is to dialing in your specific plane to a good all around rpm for the Rotax 912.



Here is a picture of what you can use to get good accurate prop pitch settings and uniformity. Here is another picture of a good prop and wheel balancer from Marc Parnes.

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prop and wheel balancer

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prop pitch tools

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_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

Av8r3400

Joined: 22 Sep 2008
Posts: 83
Location: North Central Wisconsin (KRRL)

Posted: Fri May 27, 2011 5:37 pm Post subject: Re: Prop settings

Another important thing to note on a 912 is that you must have a minimum of 5200 rpm at full power.  Less rpm than that and you are getting too high of cylinder pressure and risk blowing seals.

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_________________
Thanks,
Av8r3400

Kitfox Model IV-1200 W/912UL & IVO
Kitfox Model IV-1050 W/912UL & Warp
YouTube Videos

redrocketrider

Joined: 13 May 2011
Posts: 67
Location: Nervino airport

Posted: Fri May 27, 2011 5:56 pm Post subject: Prop settings

Thanks Roger, for your extensive explanation of the pitch/RPM. This info is 

a keeper for future reference.  Very informative and helpful, we truly 

appreciate your time and kindness in answering our question.  Haven't flown 

it yet.....so the anticipation is mounting! But need to address the issues 

at hand.

Toodie and Bob



--------------------------------------------------

From: "Roger Lee" <ssadiver1(at)yahoo.com>

Sent: Friday, May 27, 2011 1:55 PM

To: <kitfox-list(at)matronics.com>

Subject: Re: Prop settings






Hi Toodie and Bob,



There is no hard and fast answer for a pitch, for each aircraft has it's own 

drag and flight characteristics. But there is a very easy way to arrive at 

an answer for any plane and any prop. If someone has the same type plane and 

same prop they can get you close, but you may still need to dial it in for 

your plane. You need to balance your climb, cruise and fuel with this ground 

adjustable prop and you don't usually want it to be too far set for climb 

(flatter pitch) or too much toward cruise (courser pitch). Going either way 

too far defeats your best all around performance. The Rotax was built and 

has a specific range of rpms to run within. You need to set the prop to a 

pitch to achieve 5500-5550 RPM at wide open throttle (WOT). When you set the 

prop to get this rpm everything else in the middle will take care of itself. 

You are better off to cruise at 5000-5300 rpm after your prop is pitched at 

5500. This setting for a fground adjustable prop will give you the best all 

arou!

 nd performance for climb, cruise and fuel economy. (While I'm thinking 

about it set the idle rpm to 1700-1800)

Now how to get your prop setup. Tie the plane down. You want enough pitch in 

your prop to get close to a 5100-5200 static run at WOT. Once you have the 

static done that only gets you in the ballpark it's time to test fly it and 

check for rpm and this is where you can get a real pitch number for your 

individual plane. Each brand of plane and each home built can and will be a 

little different in prop pitch to achieve the same WOT rpm. So as you test 

fly your plane run it up to WOT for about 30-45 seconds. See if you are in 

that 5500-5550 rpm area. A couple rpm either way is no big deal. If your 

engine rpm tops out at lets say 5400 rpm at WOT then remove another 1/2 

degree from the pitch to flatten it a tad more. If you are running 5600 then 

add about 1/2 degree. That is all there is to dialing in your specific plane 

to a good all around rpm for the Rotax 912.



Here is a picture of what you can use to get good accurate prop pitch 

settings and uniformity. Here is another picture of a good prop and wheel 

balancer from Marc Parnes.



--------

Roger Lee

Tucson, Az.

Light Sport Repairman - Maintenance Rated

Rotax Repair Center

Home 520-574-1080  TRY HOME FIRST

Cell 520-349-7056





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=341228#341228





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- The Matronics Kitfox-List Email Forum -

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_________________
Keep the dirty side down/Blue skies. Bob

redrocketrider

Joined: 13 May 2011
Posts: 67
Location: Nervino airport

Posted: Fri May 27, 2011 5:59 pm Post subject: Prop settings

Thanks AV8R3400, much appreciated as we are in the steep learning curve and 

this is such valuable information.  Toodie and Bob



--------------------------------------------------

From: "Av8r3400" <theav8rweb(at)yahoo.com>

Sent: Friday, May 27, 2011 6:37 PM

To: <kitfox-list(at)matronics.com>

Subject: Re: Prop settings






Another important thing to note on a 912 is that you must have a minimum of 

5200 rpm at full power.  Less rpm than that and you are getting too high of 

cylinder pressure and risk blowing seals.



--------

Thanks,

Av8r3400



Kitfox Model IV-1200 W/912UL &amp; IVO

Kitfox Model IV-1050 W/912UL &amp; Warp



Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=341246#341246

- The Matronics Kitfox-List Email Forum -

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_________________
Keep the dirty side down/Blue skies. Bob

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