Hi folks.....

I have over the years collected some good info on setups, props, engines, rpm, etc.... with respect to various pattern setups. Everything from Veco .61 power up through OPS, Rossi, webra, Picco, CMB, ST, YS. And more recently I have had to dig out the old notes in an effort to help a few getting involved in vintage pattern or BPA sorta setups.

I know there is a weath of experience on here. Maybe others might find a thread full of answers a good resource.
Thus I though I would open up this thread to see what others have in their notes, or what they achieve now with different pattern engine setups.

For the sake of simplicity here, lets limit this to 2c setups. Most would be expected to be .40 to .61 size engines. Other size modern engines can be included as well as they provide an excellent reference.

In particular, identify the engine, exhaust system info, prop used, rpm observed.
For exhaust system, note if it is on a stock muffler, aftermarket muffler, or pipe.
If it is a pipe, note the pipe length (glow plug to divergent seam/weld)
Also identify your location.

Have at it.... next time you have an opportunity to run your ST bluehead, or Axe Rossi, or what ever in between.. take an observation and post it here. If you have old notes that you believe would be useful... post them here too.

Awesome Idea!!

OS 61 RF-P Hanno Special MK I
OS Header and Bolly EQ-62 Carbon Fiber Pipe....19.7" from Glow plug to first baffle
APC 12x12
10,300RPM
PowerMaster YS 20/20 fuel
Cartersville, Georgia (Elevation: 759ft)

YS 61R AR
Hatori Header and Hatori 650 Pipe....19.7" from Glow plug to first baffle
APC 12x12
10,100RPM
PowerMaster YS 20/20 fuel
Cartersville, Georgia (Elevation: 759ft)

I choose to tune more on the conservative side rather than push for absolute max RPM's...I like to ensure I have a good broad needle adjustment range which is **My Personal** key criteria while tuning...I like to pay attention to "what the needle is telling me"...When the needle adjustment starts to become "sensitive" I stop shortening the pipe and add a 1/4" or so back on to the header length...I want a good 1/4 to 1/2 a turn needle valve adjustment range...I've found I may sacrifice a couple of hundred RPM's...But it's worth it to me for the longevity of the engine...

A Hypersensitive needle is on the Razors Edge (one or two clicks between lean and rich)...While that is probably where you will see all out Max RPM's...It's a little too risky for **Me Personally**..

I'll add more to this one later..

Hi Bob,
Yes, a great idea!! I have notes on all my engine set-ups, but where?? Hopefully, I can find them
I do have another treasure trove of information: November 1989 issue of Model Aviation, page 44. It is the equipment matrix from the '89 nats pattern event and lists (among other things): engine, pipe, pipe length,plug, prop and fuel. I will try to scan it and post it here.
Regards,
Will BArtlett

OS RF-P .61
12 x 8 APC
Powermaster YS 20/20
17.5" from glowplug to baffle - OS header, unidentified pipe (pic avail if somebody can help)
11,300 rpm
Austin, TX (550 MSL)

i don't think we will see much other than .61 2c's here. it is rare but a .55ax or tower .75 gets mentioned once in a while. of course i like speed also, someone mentioned his Jett 1.00 rear exhaust here recently. we're talking real ballistic pattern there.

david

Bob, you wrote, "If it is a pipe, note the pipe length (glow plug to divergent seam/weld)." What is the divergent seam/weld. Attached is a pic of one of my pipes. A is the exhaust end and D is the header(front) end. Where is the divergent seam?

airbusdvr,
Looks like you have a Hatori pipe there, do you know if it is a 601 or a 650? The 601 is best used for higher rpm and has the reflection baffle about 1" past the first high point of the pipe. The 650 has this baffle at about 2.5" past the high point we used these on the lower rpm engine setups and long strokes. Measure by placing music wire up the pipe and force it to the side so it stops at the baffle. I will measure one of my YS 60's that is set up for high RPM and get back to you. I will have to think on the lower rpm set up, late 80's on that.

Bill

It is where the pipe stops getting larger, or point C on your photo.

On hatori pipes, a more meaningful measurement is to the first internal baffle, as Bill mentioned.
Or alternately some make a reference measurement to the factory included pressure tap screw hole (which is nearby the baffle if I recall).

Key is to provide a suitable reference location and measurement for someone else to duplicate the installation.

Since pipe shape and design can vary allot...I like to use the first baffle as my reference point because it's what really matters...As Bill mentioned the music wire method comes in very handy to "find" the first baffle if there is no weld for reference...

In the first photo below you'll see a Hatori 650 pipe and the first weld is the first baffle...

The Bolly pipes I have..The location of the first baffle is not consistent...So measuring is a must...

The other photo below shows a few different models of Hatori pipes...The 601, 650 and 700...You can sorta tell the difference in the spacing and placement of the baffle welds...The 601 is a 10cc Tuned Pipe/muffler, the 650 is 10cc (Long Chamber) and the 700 is 10cc (Super Long)...

Apparently at some point Hatori changed the "Look" of the pipes from the smooth style like airbusdrvr's to the type like mine (welds showing)...Dunno when that happened?? I have a 1987 Hatori catalog which shows the "smooth style" pipes...I forget exactly when I bought my first one..but it seems like it was the early 90's...