[VA6WGO]

Originally Posted by flyerp39

I have been using up till now an Xoar 18X8 beach wood prop but i have been told by Todd at Syssa engines that i should be using an APC 17X10 for better speed and better rpms on the engine

I understand that the canisters will help you out with the "bark" noise of the engine but the main source of noise in any setup is normally the prop.

On a 30cc engine I think that a 18(or 17)x10 THREE blade or a 19x10-20x10 two blade is more like it. It seems to me that a 18x8 or a 17x10 is bit too small. What kind of RPMs are you getting?
You should be around 8200-8500 rpms.

Wooden props are normally loud too. Carbon Fiber props are way quieter.

How are you measuring your noise?
96db at idle doesn't sound right.

I am measuring in my 40% at 10 feet away, 1 foot high 96db FULL THROTTLE using a DA150, MTW110 cans and a three blade Mejzlik 28.5X12 carbon fiber prop.

Cheers,

Will

[flyerp39]

We have been doing the tests at 3 metre's distance at idle and full throttle both and it is mostly the bark that is the noisy part and According to Todd at Syssa engine's this engine likes the higher rpms it runs better and produces a lot of power I am going to try the 17X10 prop for sure and see if that helps with the noise levels . Also most people on another forum web site are telling me that ther are running this engine with 18X6 props for thier 3D planes and are getting very good results . As it is rite now my engine with the Xoar PJA 18X8 wood prop is getting around 6900rpm Here is a link of a H9 150 P51 with the same engine and the 17X10 prop it is a very short video check it out
Cheers.

http://www.youtube.com/watch?v=r5N6eUH1kIs&NR=1

http://www.youtube.com/watch?v=r5N6eUH1kIs&NR=1

[bbbair]

There is a similar concern about noise on another thread about a DLE 20cc - perhaps the solution will be the same...


I just did a little bit of research on RCU and a fellow from Kansas City Mo says;

On my DLE 20 I plan on finding some brass tubing that is a tight slip-fit into the exhaust stack, drilling a series of holes in the top of it, and then inserting it into the exhaust stack. I will secure the tube with a sheet-metal screw.

This will act as a baffle and increase the silencing effect. I noticed the DLE 20 muffler has no baffles and the exhaust can exit the engine and go directly down the pipe. This is likely why it has been described as a bit on the loud side. I will put in the stainless steel stuffing as well and that should take care of the sharp tones.

I have done this process for years and most bystanders have commented on a "mellow" tone. When I feel the need for speed and lots of noise, I get out one of my old Quickee's with a short pipe and have at it!

(The stainless steel stuffing used, is scouring pads and you can get it at hardware stores.)

Personally, I'm going to use the brass tubing as a baffle and as required add the Stainless Steel Wool. It is a very inexpensive solution that can be removed if it doesn't work...