Reducing engine noise

[Bumpy]

Hi there microbufs

I have a Rotax 503 and would like to reduce the engine noise as much as possible (without cutting the mag switches )

Can anyone give me some information about the after muffler and intake silencer

(I am not too worried about loosing 5% performance, I am a lightweight and fly at low altitudes)

Thanks in advance!

Cheers

Phil

[Ranger]

Yes the after muffler goes just after the muffler and th intake silencer goes just before the intake. . Seriously now. Do you fly close to built up areas that you want to do this? From what i've heard is that the after muffler doesn't make all that much diffs. What i have noticed though is difference in noise with different props. Interesting to hear the comments here.

[Wallaby]

Yep, just check out Richard's Bush Baby with the 582 at Morningstar. The prop on that aerie is just unbelievable. That 582 is dead quiet in the air with that prop. A two blade wooden prop on a 503 is much louder than a 3 blade composite.

[Morph]

Wargames has an aftermuffler and it doesn't make any difference

Yes CFD's bush baby is very quiet as is all the aeries with enclosed cowls. CFD is using a Kiev prop ( IIRC ) Very very nice

A prop is one of the major contributors to noise, a beautiful big fat P-prop is lekker loud . More blades, the softer it gets

[Bumpy]

Guys, perhaps I was not clear enough, I want to reduce the engine noise for the pilot and passenger… I have a really good air-magic intercom and headsets, but the engine noise is still too loud for my liking!


Could an aftermarket silencer do the trick, or should I try get a completely different exhaust system made up by an exhaust factory?

[extra300s]

Hi there

Do you fly with helmets on? If so make sure that your own and the passengers mics are underneath the visor close to your mouth. Or get the visor bibs Zulu sells.

I have the same setup and have no such problems.

Hope this helps.

[Morph]

You get an Intake silencer and an after muffler from Comet Aviation (ex Aviation Engines) that are used to quieten the engine down. Quite a lot of local noise is generated by the air intakes

[Chris Liebenberg]

Maybe this will help you.

Some of the microphones on the headsets, if not all of them, have two pick-ups, back to back. It is like a two microphones facing opposite directions with a common diaphragm.
The all-round sounds and noises are then cancelled out, because it is picked up from both sides of the diaphragm.
When you speak into the microphone however, the sound is coming from one side only, and your voice is then transmitted clearly.

By taking off the foam tip from the microphone, inspect the position of the microphone in relation to your mouth. The microphone horn must be bend so that the one microphone is perpendicular to your mouth.

If this is not the case, your voice will not be picked up clearly, and you will have to adjust the volume of your intercom to compensate, which in turn will cause the engine noise to become louder.

Hope this helps

[ystervark7]

1) It is probably not a good idea to change the exhaust on a 2-stroke. 2-stroke exhausts are tuned and changing the exhaust will influence the performance significantly (much more than on a 4-stroke).
2) In most cases the noise is dominated by the propeller noise, then the aerodynamic noise and only then the muffler noise
see http://www.wolf-aviation.org/aircraft_noise.htm if you do not want to believe me.

To reduce noise
1) buy a better propeller. The Russian one suggested is probably the best.
2) Next add sound damping in the cockpit.
3) Wear ear protection including active noise cancelling headphones, proper ones, not the back to back microphones if you want real noise reduction

[ZULU1]

Phil, Just got back last night..posted public so others may benefit. What we can do is swop out the headcups with our very much heavier defenders. We only sell these in the UK, see http://www.airmagic.co.uk on the front page. They are considerably quieter and heavier, but aimed at the Gyro market. We have some in stock at present.

As a previous post stated the mike shields have a "magnifying glass style housing", the mic element floats in the housing and is held with the cables only, they have a large noise chamber in the rear which is designed to amplify the ambient noise. It is imperative the flat face on the front is as close and square as possible to the mouth. Squeeze the foam to feel the front. Passengers seem to think they are in a recording studio !!!
Our equipment limits frequencies between 900 hz and 3000hz, thats why music sounds "tinny" with our products. ANR is effective below those frequencies, we make that technology for Military purposes. Not as effective with a 503/582.

Steve Boxall (a Gyro pilot) from Air Magic UK has been working with and very successful in incorporating a "in ear" noise canceling ear piece in conjunction with our large headsets as described above. They plug in to the base of the headcup and may be used with or without the inner ear piece. Unfortunately he has used a UK product which means we will have to import directly. They are aimed at fixing the rear seat noise of a Gyro. He also imports a Israeli sourced helmet for the Gyro market which we can now source.

I have now established a contact locally for use of the impressive Phonak range using the "primero" series, the importer is based in Pretoria. I am looking for a Pretoria based Gyro Pilot with time available to develop this ?? This may be a very good option for Gyros.

For those based in Sandton, the Phonak Primero series are on show at the Securex show this week, (you can also see our EOD equipment on the Global Armour stand).

Cheers Paul

[Bumpy]

Thanks for the advice guys, I will try a few of the suggestions and report back in due cause.

Cheers

Phil

[Low Level]

I am looking for a Pretoria based Gyro Pilot with time available to develop this ?? This may be a very good option for Gyros.

Hi Paul

I am seriously looking at something for my gyro. I have a Microair 760 radio with buzzcom headsets. The ambient noise when flying two up is really tiring. I end up putting the intercom off, and just switch it on to communicate with the passenger. With the intercom switched off, the noise levels are almost unnoticable. I have even put a little plastic bottle around the passengers mouthpiece to try and reduce ambient noise, but it seems the problem is with the intercom on, or off. Even my mic picks up serious noise when the intercom is on, even one up.

P.S. I have turned the squelch in all directions.

[Biggles]

This is the set up one of the trikes in Peru had. It has the intake muffler Morph described and an after muffler. It was noticibly quieter. personally i don't find the 503 too niosy.