Conference vmszoo::rc

	re .1


		What more can I say.....except regarding pipes

 	The closer you tune the pipe to peak revs,the narrower the
	power band becomes.You get nothing for nothing.


	I use a pipe on my .40 ABC,I don't have it tuned optimally.I
	still get a good increase in revs,the engine throttles better,
	and it's quieter,(or at least the noise is less objectionable).


	The other drawback is of course the size.They're lenght means that
	a fair bit of weight is added behind the c of g,plus you're removing
	the existing muffler (a considerable weight,right at the front of
	the plane so if you're adding one to an existing plane you will
	need to add a sizable chunk of lead to bring the c og g forward...
	
	They also tend to be quite expensive.


       bob
	

    
    	Setting up a pipe can be a pain in the a** so To get close
    here is a simple way to start.
    	First a note is required,  Pipes and their installation
    have changed in recent yeards. In the past a pipe usually fit
    up against the header pipe from the engine. This required that 
    the header cut cut to tune the pipe. In recent yaers the pipes
    ID had been enlarged to match the OD of the header. In this way
    the ppipe can now be slipped over the header to facilitate the
    adjustment process.
    
    	To start chose the prop which you wish to fly with ie,11/7.
    Now cut the prop down 1/2 " on either end. This yields you a 10/7.
    Install the prop onto the engine and set the pipe for app. 15 ".
    Start the engine and let her rev. Read the RMP readings. Now shorten
    the pipe by 1/4 inch and repeat the running process. 
    
    	(If you have the style pipe that requires that you cut the header
    I recommend that you start from the end of the header rather than
    from a preset length.)
    
    	Continue the 1/4 adjustments and the reruns until you get to
    the point where the reduction of another 1/4' shows no improvement
    in the revs. Now measure the length of the pipe from the glow plug
    to the highest section of the pipe. Lengthen the pipe ste up now
    by 1/8 inch. If you want peak revs don't add this 1/8 inch. The
    1/8 inch helps the engine last longer.
    	Now that the pipe set up is set remove the 10/7 prop and install
    an 11/7 and go fly. This will get you close. Flying will allow for
    the final set up. You may find that you will move the pipe + - 1/4
    inches or so latter on but you will certainly be in the ball park.
    When an engine is properly set up a glow plug without an idle bar
    is prefered. If you have an engine that runs mint try a glow plug
    that doesn't have an idle bar. You'll prpbably see an increase in
    revs.
    
    						Tom

    
    
    
    		A friend of mine and I both have Great Planes Super
    	Sportster .20 planes, and are putting O.S. .25 FSR motors with
    	Tuned Pipes on them. This is our first experience with Tuned
    	pipes, and I was wondering if Anyone can tell me, step by step
    	how to tune the pipe. 
    
    			I know we have some pattern people out there.
    
    
    				Glenn 
    
    				

    Glen,
    	Here is a "short pipe" set-up.  I'm not sure if a .25 could be set
    up for a long pipe set-up.
    
    	1)  Pick a prop that you will use as your flying prop. 
    	2)  Get a second identical prop and cut off 1/2" from each tip.
    	3)  Attach the pip and prop to the engine on a stand. Run the
    	    engine up and check the revs.
    	4)  Cut app. 1/4" off of the header and repeat the run up process.
    	5)  Continue the cutting/run up process until you get two of the
    	    same readings.  You will see slow increases in revs until a
    	    peak rev is found. Not back off of the high speed needle value
    	    app. two clicks and install the full length prop.
    
    
    
    	This will give a good starting setting for your initial flights.
    More fine tuning may be necessary as the flights continue.
    
    
    Tom

Re: <<< Note 1287.1 by SA1794::TENEROWICZT >>>

Tom's process is a new one to me but it looks good as a quick/simple setup. It 
will not give the absolute peek performance but I suggest for a first time 
user of pipes that is not what you should strive for.

What I would like to add is that consistency of fuel (ie:nitro and oil 
contents) also the accuracy of props is more critical than with non piped 
engines. Experiment with different plugs of different temperatures and you may 
find some improvement in reliability and performance. 

If you use castor oil in the fuel watch for carbon build up in the pipe and
remove it if it occurs. If you plan to use pressure on the tank the best place
for the pressure nipple is on the widest point on the pipe. 

Good luck

John