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prop noise

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williamtsullivan(at)att.n
Guest

Posted: Thu Feb 28, 2008 5:45 pm Post subject: prop noise

I noticed the prop noise exceeded the engine noise while having my Firestar tied to a tree. Without the wings, as soon as the RPM's got up to about 4000, the prop started sounding like a helicopter. There is also a spot on the main boom tube right below the prop that is missing the paint. Maybe the prop tips passing 1" from the tube is generating the "whopping" noise. It is a 66" Warp Drive 2 blade ground adjustable prop. I never went past 4000rpm, as we were worried about both the tree and the rope. I imagine the noise will be quite a bit louder when the wings are on, as I have to check for aileron clearance to the prop. 

    If the prop is too close to the ailerons, will it give the aircraft a horizontal trim problem? I have looked a pictures of Firestars with both long (close to the prop) and short (lots of clearance) ailerons. How much difference is there in ease of handling, control response, and trim? What would be the recommended  minimum clearance? It doesn't look too difficult to take a couple of sections out of the aileron, but should I?

   

                                                  Bill Sullivan

                                                  Old Firestar 

 [quote][b]

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JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Thu Feb 28, 2008 8:45 pm Post subject: Re: prop noise

One inch of boom clearance is not very much, I have more on my MK III.    The closer the prop tips are to both the boom and ailerons, the more noise it will generate.    



You should us a prop extension rather than cut out your ailerons for more clearance.



Mike

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_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

DAquaNut(at)aol.com
Guest

Posted: Thu Feb 28, 2008 9:56 pm Post subject: prop noise

Bill,

  

    A prop spacer should help if you don't have one.

  

  

           Ed FF # 62 ( working  on wing)



Delicious ideas to please the pickiest eaters. Watch the video on AOL Living.

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John Hauck

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

Posted: Fri Feb 29, 2008 1:58 pm Post subject: prop noise

> One inch of boom clearance is not very much, I have more on my MK III. 

The closer the prop tips are to both the boom and ailerons, the more noise 

it will generate.



 	  Quote: 	
		   Mike


	




Mike B:



Last flight to Alaska I had 3/4" prop/tailboom clearance with a 72" Warp 

Drive.



Replaced the prop with a 70" Warp Drive on my return home, primarily for 

noise reduction.



john h

mkIII

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

Dennis.Kirby(at)kirtland.
Guest

Posted: Fri Feb 29, 2008 4:45 pm Post subject: Prop Noise

Mike Welch wrote: << I wouldn't know that the prop makes that much

noise. >>



Mike, and Kolb Friends -



I, too, was surprised to learn that the majority of my cockpit noise

came from the prop.  (Not the engine.)  Primary source of the noise

comes from the prop blades passing so close to the trailing edges of the

wing.



Following the good advice from several members of this List, I purchased

a three-inch prop extension from Saber Mfg, in Grandbury, TX.  (Near Ft.

Worth.)  A beautiful, solid aluminum CNC piece of work for $320.  It's

currently installed, but I have not yet flown with it.  Will report the

results once I fly again.



Dennis Kirby

Mark-III, 912ul, in

Cedar Crest, NM

do not archive

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a58r(at)verizon.net
Guest

Posted: Fri Feb 29, 2008 4:53 pm Post subject: prop noise

When I got my FireFly (#70), Dennis said the big hunka spacer was for prop noise reduction...and he was correct. Very quiet now, especially with hangar doors shut tight against the miserable cold! But, the spacer really does help. 



 regards,

Bob N.    FireFly 070 Old Kolb

http://www.angelfire.com/rpg/ronoy/



do not archive



 



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