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FireStar Cockpit Noise Reduction?
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slyck(at)frontiernet.net
Guest

Posted: Thu Feb 28, 2008 4:42 pm Post subject: FireStar Cockpit Noise Reduction?

The fact that we are sitting at the focal point of a cone shaped  

megaphone is the problem.

If we move our seats out in front of the windshield it will be a lot  

quieter.

-or maybe a sound diffuser behind our backs.

BB

do not archive

On 28, Feb 2008, at 3:46 PM, John Hauck wrote:

 	  Quote: 	

>

> Should be under 600 mph tip speed to reduce noise from the prop.

>

> --------

> Ray

 Hi Ray:

 We've knocked this noise thing around quite a bit over the years.   

 I'd say it it more prop noise than anything else.  Also, I think we  

 can discount prop tips approaching or exceeding supersonic speeds.   

 The Rotax engines have already taken that into consideration for us.

 I believe most of our noise is the result of a pusher engine  

 configuration with a prop that must run through air that is not  

 always clean and in close proximity to the aircraft structure.

 I have gotten down to the point where I accept my noisy airplane  

 and try to take other routes to help make it liveable for long  

 flights.  Some of us have proven that it is not so excessive we can  

 not live in our airplanes for very long periods of time.

 john h

 mkIII Noisy beyond imagination.

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captainron1(at)cox.net
Guest

Posted: Thu Feb 28, 2008 5:26 pm Post subject: FireStar Cockpit Noise Reduction?

The problem with VG's on the prop is that you will always have lots of Thrust. Even after you shut the engine down. You will need to install thrust nualifiers to keep your airplane from taking off and disappearing into the sky,  perpetually loitering in the heavens.



====================================================

---- Mike Welch <mdnanwelch7(at)hotmail.com> wrote: 



=============




 	  Quote: 	
		   Mike W:



 Once you start flying your mkIII you will probably discover the major noise

 producing item is the prop.



 By producing a very quiet engine, you will be able to hear your prop better.

 



 john h




	




  Ah, John,



  With very little MkIII flying time (read that to be "none"), I wouldn't know that the prop makes that much noise.  But I really do believe I should have a very quiet engine, and I figured if the prop was a problem, then I would just install VGs on it.



chuckling



Mike Welch



_________________________________________________________________

Helping your favorite cause is as easy as instant messaging.�You IM, we give.



--

kugelair.com

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JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Thu Feb 28, 2008 9:14 pm Post subject: Re: FireStar Cockpit Noise Reduction?

My MK III Xtra was very noisey, the prop noise going into a huge megaphone is a very good description of the problem.   The good news is that the noise can be fixed, and a Kolb can become pretty quiet.



On my MK III Xtra, I put 1/2 inch ductboard in the Cabin anywhere it faces the prop, and also under the engine ( Center Section ).  Ductboard is rigid, fireproof, oil and fuel proof on the foil side, and does a fair job of dapening sound.   I installed ductboard inside the lexan rear windows, and closed the back space of the cage where it goes against the prop.   This was so successful in reducing the noise, that I can now communicate normally in the plane with headsets and intercomm, I could not before...  The plane is now enjoyable to fly for long periods of time with out fatigue.



I did lose my view to the rear, but it was well worth it.  I dont directly behind me much, and given the choice of having an airplane that I could not fly without going deaf, and one that is comfortable to fly, losing the rear visibility is a very good tradeoff.



Second, I do use ANR headsets.  The ANR headsets did not work well alone with the huge roar of noise inside my life sized megaphone of a cockpit, but the headsets along with the ductboard made noise a Non - Issue in my plane.



I will post pictures soon.



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

gaman(at)att.net
Guest

Posted: Fri Feb 29, 2008 5:01 pm Post subject: FireStar Cockpit Noise Reduction?

John,

 I too was surprised by the MK-3 W/2200 Jabiru prop noise level..Hi tech foams offered a 1/2 in thick dense foam sound  control product, and I lined ALL the rearward facing plexiglas and the complete center cover top,.spar carry thru,doubled that piece,and wing root ends.It has foam on the inside of the fabric behind the seats to the rear of the fuselage.Now with the ANR kits installed in my 30 year old DC H-10-30's  with foam covers and leather bags over the mic's I can adjust the VOX on the intercom to talk to my passenger at cruise power settings under 2800 rpm but at full throttle it will open the mics.The ANR kits from Headsets Inc. (at)169.00 each were worth it!    G.Aman    .3iginal Message ----

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

To: kolb-list(at)matronics.com

Sent: Thursday, February 28, 2008 3:50:19 PM

Subject: Re: Re: FireStar Cockpit Noise Reduction? 

 -->  Kolb-List  message  posted  by:  "John  Hauck"  <jhauck(at)elmore.rr.com (jhauck(at)elmore.rr.com)>

  >  The  single  most  effective  thing  you  can  do  is  get  yourself  a  set  of  ANR

 	  Quote: 	
		    (Active  Noise  Reduction)  headsets.   MAN,  what  a  difference  they  made  for

  me!

  >

 	  Quote: 	
		    Dennis  Kirby

Dennis:

Got  your  bag  packed  for  MV?

I  tried  the  best  Litespeed  had  to  offer  when  they  first  came  out  without 

success.   Then,  last  summer,  I  bought  the  best  that  David  Clark  had  to  offer 

the  XL  somethings.   Neither  would  work  in  the  mkIII  cockpit.

The  set  that  worked  best  for  me  was  the  DRE6000,  which  unfortunately,  is  out 

of  business.   Got  my  fingers  crossed  my  old  set  will  keep  on  trucking.

john  h

mkIII   Bag  packed  for  MV              -  The  Kolb-List  Email  Forum  Use  the  Matronics  List  Features  Navigator  to  the  many  List  utilities  such  as  List  Archive  Search  &  Download,  7-Day  Browse,  Chat,  Photoshare,  and  much  much    -->                      -  MATRONICS  WEB  FORUMS  Same  great  content  also  available  via  the  Web    -->                   -  List  Contribution  Web  Site  Thank  you  for  your  generous                                            -Matt  Dralle,  List    -->  [quote][b]

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The BaronVonEvil

Joined: 23 Jun 2006
Posts: 76
Location: Walla Walla, WA.

Posted: Wed Mar 05, 2008 6:52 pm Post subject: Re: FireStar Cockpit Noise Reduction?

Hi All,



After reading all the helpful suggestions I now have a plan. I have ordered a propeller hub extension from Saber Mfg in TX. The prop will be moved back 3" to reduce tip noise. 



Next I will be fabricating some filler panels to provide a physical barrier between the engine and the cockpit. On the panel side that faces the engine will have a soft acoustic material to reduce the noise further.



Finally, I will close off the cockpit with a bit more lexan windscreen material to minimize my exposure to engine noise.



Hopefully, My dear sweet wife will get me an ANR headset on my birthday/Fathers Day/Xmas to complete the noise reduction process.



I have tried the panel idea already and have had some sucess using just cardboard held in place with duct tape.  The next step is to replicate the cardboard panels in foam and fiberglass to have some lightweight but stiff panels as the final product.



As the process evolves, I will try and keep everyone posted.



Best Regards

Carlos G

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Steve Boetto

Joined: 11 Jan 2006
Posts: 365

Posted: Thu Mar 06, 2008 4:26 am Post subject: FireStar Cockpit Noise Reduction?

In a message dated 3/5/2008 9:55:56 P.M. Eastern Standard Time,  grageda(at)innw.net writes:

  	  Quote: 	
		  

Hi    All,



After reading all the helpful suggestions I now have a plan. I    have ordered a propeller hub extension from Saber Mfg in TX. The prop will be    moved back 3" to reduce tip noise. 

	
  

 Carlos,

 Sounds like you bought #2 of 2 prototypes that Saber cut for me. I have not  run mine yet but unless they re cut it you will have to make some custom  washers. the clearance next to the inner hub is too tight for the bolt  head.  They could cut the inner spool to a smaller OD but they did not want  to reduce it.

 I bought some aluminum washers from ACS and knocked the edge off on the  belt sander.

 The reason for all the washers is because I used long enough metric bolts  so as to have a grip long enough to all the way through the hub.

  

 steve   

              

  



It's Tax Time! Get tips, forms and advice on AOL Money & Finance.

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The BaronVonEvil

Joined: 23 Jun 2006
Posts: 76
Location: Walla Walla, WA.

Posted: Thu Mar 06, 2008 8:55 am Post subject: FireStar Cockpit Noise Reduction?

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The BaronVonEvil

Joined: 23 Jun 2006
Posts: 76
Location: Walla Walla, WA.

Posted: Sun Mar 16, 2008 8:11 pm Post subject: Re: FireStar Cockpit Noise Reduction?

Hi All,



Well I got the prop hub extension on and tried it today. It made a noticeable difference in the cockpit noise.  I took my Db meter with me and measured about a 3 to 4 db noise reduction in the cockpit area.



I also noticed the aileron torque tube on the right wing panel did not vibrate nearly as much as before.



Overall Id say that the extension of 3" did help significantly with the noise I was experiencing and reduced propeller tip pressure induced vibration to the airframe.



The propeller is now at about 5" from the aileron torque tubes and this seems to be the magic number.



I would recommend this modification for anyone considering it.



Again thanks for all the Advice,

Carlos G

AKA

BaronVonEvil

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