Dual Exhaust

balogh wrote:There was a thread somewhere on how to build such a muffler. ..could you remind me please?

Here it is.
https://www.coxengineforum.com/t5505-a-cheap-sport-muffler
Bob

Very nice. Are you still getting good pressure with two exhaust outlets?

microflitedude wrote:Very nice. Are you still getting good pressure with two exhaust outlets?

Matt, I honestly haven't flown with the pressure-tap yet.. so I don't know how well it will work. I'm showing this as a possibility, because none of the other commercially available mufflers for Cox .049 engines have a pressure tap.

Keep in mind that my muffler design uses inter-changeable pipes having different size holes drilled in them for varying degrees of back-pressure. Dual-pipes drilled-out to the max. (.205") may not provide much (if any) pressure to a tap.. but dual pipes drilled smaller.. or a "single" pipe should. I have an assortment of pipes (.22cal ammo shell-casings) that I've drilled-out between .144" and .205" in increments of approx. .007" for testing. This gives me 9 different sizes to experiment with. Running dual-pipes having different sizes.. and placed 180 degrees apart could have cross-scavenging effects. Whether this would be beneficial remains to be seen.

Being able to successfully tap muffler pressure off a Cox .049 engine could improve stunt performance when using an external hard-tank. Testing is as easy as flying the model first without the line connected to the tank.. then attaching it prior to a 2nd flight, to one vent.. while plugging the other to see if you get a steadier engine run.

roddie wrote:
Matt, I honestly haven't flown with the pressure-tap yet.. so I don't know how well it will work. I'm showing this as a possibility, because none of the other commercially available mufflers for Cox .049 engines have a pressure tap.

I don't think you'll need a pressure tap unless you seriously change the backplate, or mount the tank too far outward.
The Babe Bee certainly runs very well on an external tank (in an RC plane) and the TD 05RC runs well without pressure from the muffler too.

That's the experiment Roddie equipped me to try, and I disappointed him by not getting around to it. I've still got the stuff and put the muffler on the Kitty Cat plane waiting for a good goof-off day to take it to the church. I have to have a launch assistant for that platter plane.

On the other hand i have made good use of Roddie's aluminum engine bearers and small wheels. My stunters have Roddie tail wheels.
Rusty

RknRusty wrote:That's the experiment Roddie equipped me to try, and I disappointed him by not getting around to it. I've still got the stuff and put the muffler on the Kitty Cat plane waiting for a good goof-off day to take it to the church. I have to have a launch assistant for that platter plane.

On the other hand i have made good use of Roddie's aluminum engine bearers and small wheels. My stunters have Roddie tail wheels.
Rusty

Hey Rusty.. no worries man. We all have a focus.. and yours lately has been on larger CLPA competition airplanes.. and you're advancing very well! I love reading about your attention to detail with every aspect concerning your building, tuning and flying experiences!