Stef; Here's a suggestion. In our business, we have a number of very accurate instruments and one of them is a sound level meter. It is calibrated and we use it in our engineering work for measuring sound levels from equipment. A couple of years ago I was checking something with it and decided to download a free sound meter app for my iPhone and compare the readings. Nu breekt mijn klomp! The little phone app gave exactly the same readings, with excellent accuracy! So, download one of the many free sound meter apps that are available. Find out what the Dutch aviation authorities use as a standard of measurement that they will require when they check your airplane. For example, 90 dB at 100 ft from the airplane on the runway in full-power takeoff- or whatever it is. Take some measurements of airplanes that are certified, and then have your Dad or a friend take the same measurements of your airplane in the same conditions so you can get an idea of how close you are to the limit. Record the conditions so when you make a change like the catalytic converter or a different silencer, you can take new readings under the same conditions to see if there is an improvement. Try different things until you're satisfied so you don't end up having to pay for a followup test by the inspector.
As an example, when my friend Paul Martin had his KR2 with 1835 VW engine, it had 2-into-1 exhausts on each side and he wanted to see if he could get it quieter. We tried installing exhaust pipe tips from a standard VW engine onto the ends of the pipes on each side using worm drive clamps and took measurements before and after. After multiple test runs to verify results, there was just a slight improvement; not worth it. Paul was going to continue experimenting using motorcycle exhaust baffles that slip inside the ends of the pipes, but he sold the airplane before we could try that experiment. Oscar Zuniga Medford, OR Air Camper NX41CC, A75 power _______________________________________________ Search the KRnet Archives at https://www.mail-archive.com/krnet@list.krnet.org/. Please see LIST RULES and KRnet info at http://www.krnet.org/info.html. see http://list.krnet.org/mailman/listinfo/krnet_list.krnet.org to change options. To UNsubscribe from KRnet, send a message to krnet-le...@list.krnet.org
