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Cox Sportsman .15 R / C and Homemade Muffler
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Cox Sportsman .15 R / C and Homemade Muffler
Hi everyone, this time I wanted to make my Cox Sportsman .15 a little quieter.
A .15 cubic inch motor and with these wide exhaust ports makes itself heard !! ..., so I decided to make a muffler from a solid aluminum alloy bar.
Here in the video are the results, I really like how your sound is now, it allows you to be more sociable in the club haha .... I hope you like the video!
A .15 cubic inch motor and with these wide exhaust ports makes itself heard !! ..., so I decided to make a muffler from a solid aluminum alloy bar.
Here in the video are the results, I really like how your sound is now, it allows you to be more sociable in the club haha .... I hope you like the video!






MauricioB- Top Poster
- Posts : 3457
Join date : 2016-02-16
Age : 52
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1/2A Nut- Top Poster
Posts : 3345
Join date : 2013-10-20
Age : 60
Location : Brad in Texas
Re: Cox Sportsman .15 R / C and Homemade Muffler
Nice, good job, throttles real well. Did I miss the part where you made a rear carb intake?
Cribbs74- Moderator
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Join date : 2011-10-24
Age : 49
Location : Tuttle, OK
Re: Cox Sportsman .15 R / C and Homemade Muffler
Yes y no how loud the .15 is m'y self use mufler y have fit on the sportsman y did try rc wit carb fix wit pice tube just using the valve on the carburator work Good y have two of them tink of build model for them use twin .10 To .15

davidll1984- Diamond Member
- Posts : 2106
Join date : 2020-02-12
Age : 38
Location : shawinigan
Re: Cox Sportsman .15 R / C and Homemade Muffler
Cribbs74 wrote:Nice, good job, throttles real well. Did I miss the part where you made a rear carb intake?
Hello friend! ... actually now after a few years I have manufactured the silencer. It's what I show here ...
But the history of this engine and trying to control the speed, goes back a few years ago, where many members of the group gave me ideas of how to do it, it was then that Brad gave me the option of placing an air valve as shown here:
https://www.coxengineforum.com/t9410-video-cox-sportsman-15#119842
Based on Brad's idea, I started rehearsing and finally succeeded.
But as I said at the beginning, now I show the manufacture of the silencer.
Last edited by MauricioB on Sun Feb 21, 2021 12:38 am; edited 2 times in total
MauricioB- Top Poster
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Re: Cox Sportsman .15 R / C and Homemade Muffler
1/2A Nut wrote:Very nice Mauricio a much more friendly engine with the header and
manifold keeping the tone of the exhaust easy on the ears! If you can
find these brass fittings makes for a simple solution for good breathing.![]()
![]()
thank you dear friend

MauricioB- Top Poster
- Posts : 3457
Join date : 2016-02-16
Age : 52
Location : ARG
Re: Cox Sportsman .15 R / C and Homemade Muffler
davidll1984 wrote:Yes y no how loud the .15 is m'y self use mufler y have fit on the sportsman y did try rc wit carb fix wit pice tube just using the valve on the carburator work Good y have two of them tink of build model for them use twin .10 To .15![]()
Hi David ... the engine works with great power, tomorrow God willing, I will do some flights!
MauricioB- Top Poster
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Re: Cox Sportsman .15 R / C and Homemade Muffler
Congratulations Mauricio. Is the muffler held down on the crankcase by the lowermost cylinder fin after you screw in the cylinder, like most of the COX mufflers?
balogh- Top Poster
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Location : Budapest Hungary
Re: Cox Sportsman .15 R / C and Homemade Muffler
balogh wrote:Congratulations Mauricio. Is the muffler held down on the crankcase by the lowermost cylinder fin after you screw in the cylinder, like most of the COX mufflers?
Thanks very much friend!.
No Andras, in this case it is held by the second fin of the cylinder counting from the bottom up.
It turns out that the base skirt of the cylinder is the same size as the bottom fin, therefore, as this muffler is one piece, the drilling does not stop or seal.
In the drawing you will see the sketch of how it really fits and is firmly fixed.
Points A and B were the idea of placing Oring in case it were necessary, but seeing the operating experience, everything is very well sealed and watertight, so that Oring is not necessary. Anyway I can place them as follows:
A) between fin 1 and fin 2, an Oring can be placed there
B) By making a groove in the muffler, an Oring can be accommodated.
But I repeat, A and B were an option in case of gas leaks and afterburners, but everything seems to go very well without them.

MauricioB- Top Poster
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MauricioB- Top Poster
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Location : ARG
Re: Cox Sportsman .15 R / C and Homemade Muffler
Well, the result in flight was perfect, the engine runs very well in all positions and acrobatics.
The engine sound improved considerably making it much more pleasant.
Here in this video, there are two flights, the first with zero wind and the second with wind between 35 and 40 km / h.
I like how this Cox Sportsman .15 engine turned out with a lot to give and enjoy ahead!
The engine sound improved considerably making it much more pleasant.
Here in this video, there are two flights, the first with zero wind and the second with wind between 35 and 40 km / h.
I like how this Cox Sportsman .15 engine turned out with a lot to give and enjoy ahead!







MauricioB- Top Poster
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Re: Cox Sportsman .15 R / C and Homemade Muffler
A very beautiful flight. It's been a long time since I flew a .15 sportsman or any other plane i
miss it. My controller fail lost signal twice with two different plane my secon controler is in drone reparation place for the seting of one of my new toys free style 250 drone y use m'y litle 4x4 Every day. since the last modification its lots of fun like noting To stop him
miss it. My controller fail lost signal twice with two different plane my secon controler is in drone reparation place for the seting of one of my new toys free style 250 drone y use m'y litle 4x4 Every day. since the last modification its lots of fun like noting To stop him
davidll1984- Diamond Member
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Re: Cox Sportsman .15 R / C and Homemade Muffler
Flight with Snark 5T and Cox Sportsman .15 r / c.
Camera on board ..
an air record of our club, hangar area and our model airplane runway ...
I hope you enjoy the video...
Camera on board ..
an air record of our club, hangar area and our model airplane runway ...
I hope you enjoy the video...
MauricioB- Top Poster
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Re: Cox Sportsman .15 R / C and Homemade Muffler
Thank you Mauricio, very well done. It is quite energizing to watch such a flight in the morning when you wake up and check CEF entries on the telephone while still in bed!
Where was the camera fixed on the plane, was it under the fuselage, crosswise? My small keychain camera sits mostly on the wing near the tip in order to avoid castor droplets hitting the lens.


Where was the camera fixed on the plane, was it under the fuselage, crosswise? My small keychain camera sits mostly on the wing near the tip in order to avoid castor droplets hitting the lens.
balogh- Top Poster
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Re: Cox Sportsman .15 R / C and Homemade Muffler
balogh wrote:Thank you Mauricio, very well done. It is quite energizing to watch such a flight in the morning when you wake up and check CEF entries on the telephone while still in bed!![]()
![]()
Where was the camera fixed on the plane, was it under the fuselage, crosswise? My small keychain camera sits mostly on the wing near the tip in order to avoid castor droplets hitting the lens.
Thank you very much András for your comment, I am very happy you like the video.
The engine really works perfect, everything built into it like the air valve and the silencer seems to have always been there, since it behaves 10 points out of 10.
It allows you to make controlled flights and enjoy this powerful engine a lot.
Here I show you how to install the camera, everything is very simple. A plywood board, held up with rubber bands and built-in foam rubber to minimize vibrations. Everything turned out very well.
I hope you can and keep flying, I really wish it to be so!


Thanks again friend!



MauricioB- Top Poster
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MauricioB- Top Poster
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Join date : 2016-02-16
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Location : ARG
Re: Cox Sportsman .15 R / C and Homemade Muffler
That was a fantastic flight video! Felt like I was in a passenger seat looking out the window. what Fun! Dancing with Dogs...not quite the same as wolfs but just as much fun.
Marleysky- Top Poster
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davidll1984- Diamond Member
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Re: Cox Sportsman .15 R / C and Homemade Muffler
Marleysky wrote:That was a fantastic flight video! Felt like I was in a passenger seat looking out the window. what Fun! Dancing with Dogs...not quite the same as wolfs but just as much fun.
Thank you very much for your comment Marleysky!! Thank you again ... I'm glad you like the flight!
These dogs are great, a bit of affection and they return all their affection ... there are 4 of them and they walk together throughout the club, there they have the whole property to run, they have water and food, so they have a great time.




Now I also have personal canine custody for my models hahaha




Last edited by MauricioB on Tue Mar 02, 2021 5:49 am; edited 1 time in total
MauricioB- Top Poster
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MauricioB- Top Poster
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Join date : 2016-02-16
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