Great-North

Im building a GP extra 300s .40. Im planning on putting a OS 50sx in it but was wondering if a i can just use the stock muffler or do i have to put on a pitts? I am putting the engine on sideways. Thanks

Scar

My Feedback: (3)

There are lots of these planes out there with a stock muffler sticking out the bottom right. Not a bad option. If you don't want to cut so much out of the cowl, you can use a Pitts.

By all reports, these are good flying planes, even with a .40. I look for yours to be a rocket, with that .50.

Best wishes,
Dave Olson

Great-North

Im hoping it will be a rocket. For the price of a pitts muffler i wasn't sure if it was acrually worth it. If there are many who use stock exhaust i think i will too. I just hope it doesn't blow right over the servo in my wing.

Gringo Flyer

My Feedback: (18)

I wouldnt worry a lot about the left over exhaust on the servo, lots of planes fly with servos exposed to the exhaust without problems. I have even seen servos mounted in the cowl that were absolutely filthy but kept on running.

If you are still worried about the servo put an exhaust deflector on.

TexasAirBoss

My Feedback: (22)

There might be a problem with running a stock muffler.

When the engine is inside of a cowling you need to have enough air flow to keep the engine cool, right ?

To maintain the proper airflow, a ratio of cowl inlet area to cowl exhaust area must be maintained. About 1 to 2 1/2.

With a stock muffler, the hole required to fit the muffler often extends so far forward that it actually faces the airflow and becomes inlet area.

Which means that you need one very large hole in the bottom of the cowl to maintain the proper ratio.

For this reason, I suggest using a Pitts muffler, (unless the stock muffler fits inside the cowl)

SamD

Check the Dec. issue of RCM and Clarence Lee's engine column. He notes a Magnum engines Pitts muffler as a "bargain". Checking this link: http://www.hobbypeople.net/gallery/279940.asp shows a price of $22.95. Looks like it even includes a couple of pieces of silicone tubing. Not 100% certain but this should fit the OS SX .50. If you do use it, ditch the gaskets- you won't be able to keep the bolts tight.

Great-North

Thanks for all the info. I f i do go with a pitts which on gives the most pressure for the fuel tank? I've heard that some are better than others in that area. Again this would be for a OS 50sx.