I have a TF Giant P-51 powered by a G-45
with a B&B Box Muffler. I haven't flown it
much, but now we are having noise issues
at out flying field.

Can anyone make some recommendations
for this engine/airframe combo that might
decrease the db output?

Any input or thoughts will be appreciated.

Thanks!

Johnny C!

The B&B side dump mufflers are noted for their increase in performance and noise, while a Pitts style muffler from Bisson, Jtec or Slimline will give a significant reduction in noise over the B&B with a small decrease in rpm.

Karol

Karol,
I tried a Slimline Pitts several months ago,
trying to eliminate the large cowl opening.
I found that with the Slimline would have
required moving the motor at least 1/4"
forward to allow it to clear the firewall.
That was a modification that required
much more work than I wanted to
tackle.

Is there another brand that will clear
the firewall? I have the G-45 mounted
with the cup mount.

Thanks for the response.

Johnny C!

Too bad there is no room to put a cannister in the fuse. I would try to make a custom muffler out of sheet metal with baffles in side. You could even pack it with fiberglass like 2-stroke dirtbike silencers. If you lived closer, I'd help you do it. Sounds like a fun project.

It is quite possible that most all brands will be very similar in size, however if you only need a 1/4" more space have you thought about modifying the Slimline to fit. Otherwise you might have to do as Mr Bigg suggested and make a custom muffler and maybe use the basic dimensions of the Slimline as a guide.

Karol

This Ultimate with G62 originally had a Slimline wrap around pitts installed. You can see the modification I made to the bottom front of the engine box to accomodate it. It really isn't much work, and though an in fuse silencer would be most beneficial for sound, this would require much less effort.

I opted for the DL50 muffler on my 62, because not only was the power better, but I lost 8oz of weight as well. My club also doesn't fly where any strict sound requirements are in place.

...oh, and your prop size, rpm and selection will certainly have an affect on sound, by the way.

I don't know whether a Bisson side mount muffler would fit in your cowl or not but the noise level on these mufflers is quite a bit lower than the B&B. These usually hug the cylinder quite closely.

On a scale project this year using a 3MM 53, I fabricated a large, side mount steel box muffler with a 1" exit pipe. Steel because I needed the nose weight and because it was easy to weld .... the muffler has very low restriction and is very quiet. There are no baffles of any kind inside. I believe the muffling effect is good because the box has a very large volume. But then, I'm not a muffler engineer and didn't really know what to expect until the engine was started for the first time.

Depending on the P-51's engine mounting and firewall arrangement, looks like Chad might have just pointed you in the right direction to solving your space problem.

Karol