Noise Limits for FAI

[adriancwong at earthlink.net]

I have been using the 15.5x12 4 blades on my 140 and 160 DZ with good results. However, on a windy day, it struggles a bit on the up line, but slows down nicely on the down line.

Adrian



-----Original Message-----
From: Amram Privat <amram at leshed.com>
Sent: Jun 27, 2005 1:04 AM
To: discussion at nsrca.org
Subject: Re: Noise Limits for FAI

Hello Bill
Just finished series of tests with OS140RX  20% nitro 17% oil.
OS header and ES 20" CF tune pipe and Hyde ARIA mount. Test is 3 meters from the model on grass field:

APC 17x12       2 blades = ~ 91.5 - 93dB   (Very powerful but risky for competition and slow down rate is low)
APC 16x14       2 blades = ~ 89 - 90dB      (Powerful but fly too fast slow down rate is low)
APC 16x12       2 blades =    Not tested yet
APC 15.75x13  3 blades = ~ 88 - 90dB      (Good performance, slow down rate is better but not enough)
APC 15.5x12    4 blades = ~ 86 - 98dB      (Best flying on normal conditions. Will have not enough power on strong windy day, very good speed control)

Not tested but I am tending to think that for YS160 the 4 blades will be a good solution.

Amram


  ----- Original Message ----- 
  From: Aviram Arbel 
  To: discussion at nsrca.org 
  Sent: Monday, June 27, 2005 9:35 AM
  Subject: RE: Noise Limits for FAI


  Hi Bill
  I'm using APC 4 blade 15.5X12 30% CP - 87-89 DB 

  Aviram



------------------------------------------------------------------------------
  From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On Behalf Of vicenterc at comcast.net
  Sent: Monday, June 27, 2005 3:50 AM
  To: discussion at nsrca.org; discussion at nsrca.org
  Cc: William Ahrens
  Subject: Re: Noise Limits for FAI


  Hi Bill,

  Did you check wiht 3 or 4 blade prop?  Probably you could reduce it wiht those props.

  Vicente

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

    > Group 
    > 
    > For a YS 160 what prop and exhaust will get me to 94dB(A) and work well. 
    > 
    > Currently using a 17 x 12 wide with EX Composite pipe and 30 percent Nitro. 
    > Today at about 101 degrees heat index my plane measured about 98dB(A) with a 
    > Radio Shack meter. 
    > 
    > Thanks 
    > Bill 
    > 
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