Bump 

   EX-TIMING   AERO 40\51\61\65   AERO 75 & 85   OPS/OS/ST   OPS/OS/YS   OS/YS   
RPM   130degree   135degree   133 degrees   140degree   145degree   150degree   155degree
9000   18 1/2    18.5-18.75   18.3-18.7   19 5/8   20 1/4   20 7/8   21  1/2
9500   17 3/4   17 3/4 -18   17.1.4-17.9   19   19 5/8   20 3/8   21   
10000   17  5/16   17.5-17.25   17.25-17.5   18 3/8   19       19 3/4   20 1/2
10500   16 3/4   17-17.25   16.9- 17.2   17 7/8   18  5/16   19       19 7/8
11000   16  5/16   17-16.75   16.7 17   17  5/16   17 7/8   18  5/8    19 1/4
11500   16   16  5/16      16 3/4   17 3/8   17 3/4   18 3/4
12000   15 3/4   16 1/8      16 3/8   16 3/4   17 1/2   18 1/8
12500   15 3/8   15 3/4      16  1/16   16 3/8   17       17 5/8
13000   14 7/8   15 3/8      15  9/16   16   16 1/2   17 1/8
13500                     
             PIPE     TUNING        CHART by   Randy Smith      

   MEASURE taken    from  the   GLO-      PLUG  to  FIRST   BAFFLE                     
   FOR THE P.A. 40 - 61 ENGINES                  
   A Good PIPE Starting Point         16 3\4to 17.5 inches      PROPS 11,5 FOR THE 40,12 FOR THE 51      
   12.5 to 13 INCHES FOR THE 61 3.8 TO 4 PITCH  10,500-11,200 RPMs   For the 61 @      3.8 PITCH    10,500 -11,200 RPM         
   IF  IT IS  TOO HOT OR COMES ON TOO STRONG  MOVE  OUT  toward 17.5  INCHES                     

   IF PLANE SPEEDS UP DURING ( normally the back half)THE FLIGHT MOVE PIPE OUT ,                     
   IF PLANE SLOWS DOWN DURING (normally the back half of the flight)FLIGHT MOVE PIPE IN SHORTER   Make sure the fuel tank is good and not causing any slow down or speed up problems before moving pipe                  
best props pipe combo lenghts                        
40   bolly 11.75 x 4.25  cut to 11.3-11.5 inches         pipe 16.75            
51   bolly 12 x 4.25 3 blade as is     bolly 12.2 x 4.2 2 b;ade as is               pipe 17 in to 17.25      
61   12x 4.25 3 blade  13 x 4.5 3 blade  cut to 12.5   or  13 x 4.5  2 blade  as is                  pipe 17 to 17.5   
65   bolly 13 x 4.5 3 blade or  13.75 x 4.5  3 blade            pipe 17 to 17.5         
75   bolly 15 x 4.7  2 blade ,13 3\4 and 14 inch 3 blades 4to 4 3\4 pitch Bolly 14 to15x 4.5 2 blade            pipe 17.25 to 17.75         


This is a tuning-timing chart for Several engines

I will write more when I get a little time

Randy

Hi Wayne

You see many types used  but  the most  common  is  uniflow  suction, I would  advise  against  pressure  on any motor and  setup  unless  you just  have to have it  to  work.
most  everyone  has  gone  off of  pressure  for  pipe  setups

Randy

Randy,

I have been running the 75 on a bolly 13.75 3 bl.  It is pitched up a bit.  The motor is very happy at 8700 rpms.  I am thinking my pipe length should be about 18.5-19" range.  Will this be sufficiant to hold the motor off should it want to wind up in the wind?

The reason I ask is because right now I dont have enough pipe coupler to get the pipe longer than 17.5 and if there is any wind with this higher pitched prop it winds up something awful.  But in calm conditions the motor at 8700 is in a BIG FAT 4 cysle all the way through and very steady. 

In the old days of the 65 I ran a 12" 4 blade at 3.6 sataion 8-3.2 last station and it would fly the same spped no matter what was going on.  I had the pipe in about 17.125 and the rpms up to about 10500-10750.  On calm days leave the same prop on and screw it in to 11000 and it would fly the same exact flight but have more in the corner.  But the prop was so flat it was a giant break on the motor.  It could reva nd rev and go nowhere.

I want the same type of breaking action from the pipe on my 75 but with long props with a little higher pitches.  Will I get it?

I know I may need to pitch down a little to come in around 9200 I am thinking that is a good number.

Your thoughts please.

Thanks in advance.

Randy,

I have been using 5% nitro with excellent results.  The higher nitro was giving me run problems.  I went away from that.  I will run the longer pipe and let you know how it works out. 

Thanks

Doug