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UltraStar engine woes nearing a conclusion

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jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Fri May 23, 2008 7:41 am Post subject: UltraStar engine woes nearing a conclusion

Recap: 



My UL-202 was running to hot CHT's and EGT's and no amount of messing with jets and carb needle settings could correct the problem.



Because the engine had been repaired after a seizure by the previous owner I feel it is suspect but I got a spare Cuyuna 430 with the deal.

.

.

New:



I swapped out my Cuyuna UL-202 for a 50 hr Cuyuna 430 and it is behaving the same way producing the same high CHT's and EGT's.



It also can not get more than 5900 rpm like the UL-202



The only conclusion I can draw is that I have to much prop loading.



Its a 50" Ritz wood prop, but there is no indication of pitch anywhere on it.



I figure that I will start cutting down the tips 1/2 inch at a time until I get the RPM up to the recommended 6200-6400 range and see what CHT's and EGT temps result.



Is there an easy way of measuring the prop pitch, or do I just get out the protractor and a calculator and figure it out using trigonometry?

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

slyck(at)frontiernet.net
Guest

Posted: Fri May 23, 2008 8:17 am Post subject: UltraStar engine woes nearing a conclusion

Ray, pitch for "real" airplanes and us guys is two different worlds.

It would be nice to see a conversion chart (is there one out there?)



I have come to like the degree method because it is easily measurable  

by the owner.

10 degrees is a fairly fine pitch, 14 and over is for the fast, high  

HP guys.

I'm currently at about 11 1/2 with a 70" two blade which gives me  

about 4900 on take off roll.

I'm going to squeeze it back to about (this ain't a precision deal  

here folks) 10 1/2

so I can impress the runway turtles.

BB, managing to fly on 55 hp with a fat MkIII

looking nicer here now

do not archive



On 23, May 2008, at 11:41 AM, jb92563 wrote:



 	  Quote: 	
		   



 Recap:



 My UL-202 was running to hot CHT's and EGT's and no amount of  

 messing with jets and carb needle settings could correct the problem.



 Because the engine had been repaired after a seizure by the  

 previous owner I feel it is suspect but I got a spare Cuyuna 430  

 with the deal.

 New:



 I swapped out my Cuyuna UL-202 for a 50 hr Cuyuna 430 and it is  

 behaving the same way producing the same high CHT's and EGT's.



 It also can not get more than 5900 rpm like the UL-202



 The only conclusion I can draw is that I have to much prop loading.



 Its a 50" Ritz prop, but there is no indication of pitch anywhere  

 on it.



 I figure that I will start cutting down the tips 1/2 inch at a time  

 until I get the RPM up to the recommended 6200-6400 range and see  

 what CHT's and EGT temps result.



 Is there an easy way of measuring the prop pitch, or do I just get  

 out the protractor and a calculator and figure it out using  

 trigonometry?



 --------

 Ray



 Kolb UltraStar (Cuyuna UL-202)

 Moni MotorGlider

 Schreder HP-11 Glider

 Riverside County, CA



 Do Not Archive





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=184522#184522

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Fri May 23, 2008 8:55 am Post subject: UltraStar engine woes nearing a conclusion

-------------- Original message ----------------------

From: "jb92563" <jb92563(at)yahoo.com>

 	  Quote: 	
		    

 Is there an easy way of measuring the prop pitch, or do I just get out the 

 protractor and a calculator and figure it out using trigonometry?


	


Measure the angle and do the trig.



-Dana

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Fri May 23, 2008 8:59 am Post subject: UltraStar engine woes nearing a conclusion

-------------- Original message ----------------------

From: robert bean <slyck(at)frontiernet.net>

 	  Quote: 	
		  

 10 degrees is a fairly fine pitch, 14 and over is for the fast, high  

 HP guys.


	


10 or 14 degrees... where?  That doesn't tell much, as the angle varies along the blade due to the twist.  Near the root the angle is very large and near the tip it's very small.  You need to specify the radius where it's measured, from which you can then calculate the pitch (in inches).



-Dana

slyck(at)frontiernet.net
Guest

Posted: Fri May 23, 2008 11:11 am Post subject: UltraStar engine woes nearing a conclusion

The tip

On 23, May 2008, at 12:56 PM, d-m-hague(at)comcast.net wrote:

 	  Quote: 	

  -------------- Original message ----------------------

 From: robert bean <slyck(at)frontiernet.net>

>

> 10 degrees is a fairly fine pitch, 14 and over is for the fast, high

> HP guys.

 10 or 14 degrees... where?  That doesn't tell much, as the angle  

 varies along the blade due to the twist.  Near the root the angle  

 is very large and near the tip it's very small.  You need to  

 specify the radius where it's measured, from which you can then  

 calculate the pitch (in inches).

 -Dana

jbhart(at)onlyinternet.ne
Guest

Posted: Fri May 23, 2008 12:38 pm Post subject: UltraStar engine woes nearing a conclusion

At 08:41 AM 5/23/08 -0700, you wrote:

 	  Quote: 	
		  

Is there an easy way of measuring the prop pitch, or do I just get out the 

protractor and a calculator and figure it out using trigonometry?
	


 	  Quote: 	
		  


	


Ray,



No trig is required.  Using a bubble level, level the leading edge of the 

blade that is being adjusted. Measure the angle to the vertical using an 

incline meter across the blade tip.  Adjust the blade to the new desired 

change in angle.  Then rotate each unchanged blade into the level position, 

and repeat the change.  If you have an IVO then you only have to do this 

once.



To find the final pitch, repeat the blade leveling (up blade) and recorded 

the tip angle to the vertical.  Then rotate the blade 180 degrees, level 

the same leading edge (down blade), and measure the same angle.  Add the 

two together and divide by two and you have the blade pitch. 



Jack B. Hart FF004

Winchester, IN

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Fri May 23, 2008 1:15 pm Post subject: UltraStar engine woes nearing a conclusion

At 03:08 PM 5/23/2008, robert bean wrote:

 	  Quote: 	
		  



The tip


	


Still not enough... pitch is a function of blade angle and the radius where 

it's measured.



Pitch (in inches) = tan(blade angle) * 2*pi*R



Many props don't have a constant pitch, so it's typically measured 75% of 

the way out from the hub.



-Dana

--

  Work is underway on drafting a new constitution for Iraq.  Why don't we 

send them ours?  It worked for 200 years, and we don't use it any more.

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Fri May 23, 2008 1:20 pm Post subject: UltraStar engine woes nearing a conclusion

At 05:35 PM 5/23/2008, Jack B. Hart wrote:



 	  Quote: 	
		  No trig is required.  Using a bubble level, level the leading edge of the

blade that is being adjusted. Measure the angle to the vertical using an

incline meter across the blade tip.  Adjust the blade to the new desired

change in angle...


	


Jack, trig IS required to get the pitch.  What you've described is getting 

the blade _angle_, which is what you use for setting an adjustable prop... 

what Ray needs is the pitch (in inches) of his fixed blade prop.



Ray:  Measure the angle of the back side of the blade 75% of the way out 

from the hub (for the standard 50" Ultrastar prop that's 18-3/4" out.  Then:



Pitch (in inches) = tan(blade angle) * 2*pi*18.75



I've never measured mine, but I'm told the standard US prop is a 50X30 (30" 

pitch).



-Dana



--

  Work is underway on drafting a new constitution for Iraq.  Why don't we 

send them ours?  It worked for 200 years, and we don't use it any more.

jbhart(at)onlyinternet.ne
Guest

Posted: Fri May 23, 2008 2:13 pm Post subject: UltraStar engine woes nearing a conclusion

At 05:15 PM 5/23/08 -0400, you wrote:

 	  Quote: 	
		  



Jack, trig IS required to get the pitch.  What you've described is getting 

the blade _angle_, which is what you use for setting an adjustable prop... 

what Ray needs is the pitch (in inches) of his fixed blade prop.



Danad,
	




OOPS!



You are absolutely correct.



Jack B. Hart F004

Winchester, IN

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Fri May 23, 2008 2:37 pm Post subject: Re: UltraStar engine woes nearing a conclusion

Thanks guys.



I sat down and crunched some numbers.



PI = circumference of circle in radians



Circumference = PI x Diameter



hence Circumference= 3.14159 x 50" 



Pitch = distance advanced during 1 complete rotation not accounting for slippage etc.



Pitch = Tan(Blade Angle (at) 75% to tip) x (3.14159 x 50")



So for a 50x30 prop the angle at 75% out to the tip should be about 11 Degrees.



If I measure more than this then I know my prop pitch is definitely to high.



Being a fixed pitch wood prop the easiest solution is to cut the tips down. 



The rpm should go up, and hopefully the CHT's and EGT will come down making my engine and me happy again.



Then I can finally fly this thing and learn what flying a Kolb is all about.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Fri May 23, 2008 6:10 pm Post subject: UltraStar engine woes nearing a conclusion

Ray, not quite correct:



At 06:37 PM 5/23/2008, jb92563 wrote:



 	  Quote: 	
		  I sat down and crunched some numbers.



PI = circumference of circle in radians


	


No, radians are a measure of angles.  2pi radians = 360°.



 	  Quote: 	
		  Circumference = PI x Diameter



hence Circumference= 3.14159 x 50"


	


Correct, but read on.



 	  Quote: 	
		  Pitch = distance advanced during 1 complete rotation not accounting for 

slippage etc.



Pitch = Tan(Blade Angle (at) 75% to tip) x (3.14159 x 50")



So for a 50x30 prop the angle at 75% out to the tip should be about 11 

Degrees.


	


No, you need to use 75% of the diameter too, you use Pi * 50 * .75  so the 

angle at the 75% point (18-3/4" from the centerline) should be 14.3° 

(arctan(30/(pi*50*.75)).



 	  Quote: 	
		  If I measure more than this then I know my prop pitch is definitely to high.



Being a fixed pitch wood prop the easiest solution is to cut the tips down.


	


Be sure you balance it after you cut it!



One thing you might want to try if you're trimming the prop anyway... I'd 

try it myself if I had to modify a prop ... is the tip mod described on 

Jack Hart's website:

http://www.thirdshift.com/jack/firefly/firefly100.html



-Dana

--

  Inflation is a result of legalized counterfeiting.

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Fri May 23, 2008 9:34 pm Post subject: Re: UltraStar engine woes nearing a conclusion

Thanks Dana for validating and correcting my formulas.



I'll check out those prop tips and measure my prop pitch in the morning.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Tue May 27, 2008 6:48 am Post subject: Update: UltraStar engine woes nearing a conclusion

I cut down the prop tips yesterday by 3/4"



So now I have a 48 1/2 " diameter instead of 50".



I ran up the engine (Cuyuna 430) and got a bit of belt slipping that allowed 6400 rpm but once that stopped it steadied at 5800.



Not really what I expected as I figured rpm would go up a lot more.



However after running the engine at full power for a a good 5 minutes it was apparent that the CHT's were staying a lot lower.  



It pretty much took the full 5 minutes for the engine CHT's to creep up to their highest temps.



The front fan side cylinder only went as high as 365 and stopped climbing and the rear cylinder only went to 408 which is slightly over the 400 redline.



The EGT's however went to 1400 so perhaps my jetting is a bit lean.



I need to find my notes on what the various EGT's &CHT's mean to see what needs to be done next.



I also noticed that there seemed to be significantly more static thrust.



Looks like I'm getting closer to solving the engine problems.

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

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