Noise: Diesel vs. Glow

[frank mccune]

     Hello All:

     Would somebody do a comparison between a glow engine with a muffler and the same engine converted to Diesel sans a muffler.  I would and could do it if I had access to a Db. meter. Anybody willing to loan or sell me a meter?  Perhaps a member would willing to perform this test and post the results here.

     I have several engines with DDD conversion heads and mufflers to use for making tests.

     Suggestions/comments

     Frank

[Steve Helmick]

I don't have a dB meter, but I know that the meter/engine/prop/meter distance and direction will need to be exactly the same for all tests to get meaningful results. Size of prop and rpm will be major factors in the noise produced. I dunno if the higher compression and different fuel will matter or not.

One of our club members bought a dB meter, with the idea being to help us get/keep a flying field. IIRC, I think it was under $100, but you know what they say...a Benjamin is the new Twenty. Some local PD's might have a dB meter, but the officer probably won't know what the prescribed distance from meter to sound source is.    Steve

[Jim Kraft]

Just from hearing them I would say a diesel without a muffler is about the same as glow with a really good muffler. The Brits are really the diesel guys. Most all of their planes are powered by diesels. Lots of advantages to running them. Smaller tank, no battery to go bad. No glow plug to go bad. Lots of videos on you tube of running diesels.

Some cannot stand the stink. Others love it. And they do run pretty dirty with lots of soot. Everything is a trade off somewhere. Diesels will swing a larger prop for the same displacement.

Having said all of that, I have never run one personally. I have a Taifun Tornado 15 that is in super shape with a ball bearing crank. Never took the time to mix some fuel to run it. It was in a batch of other engines I bought. After watching the Brits run them kind of gives me the desire to get mine running.

On many of their small free flights they lower the compression to detune them for a slow climb out. Fun to watch.

[john e. holliday]

As with glows it depends on the engine you are talking about.  I have a Rivers taht I put ear muffs on me as it is the loudest diesel I have ever run.  I played with F2C with several pilots before I gave up on keeping a pilot.   Now I need a source of good ether as I don't think the John Deere Starting fluid is up to par.  O f course I'm out of Amyl Nitrate also.   But as stated diesel are fun to run  and with Bob Hill(now deceased) as my pilot we played with diesels on combat planes.   I have a British Peacemaker that has a couple of flight with the Rivers.   Still needs more break in I think.  Ran Super Tigres and Rossi's  and they were easy.  I sold my Nelson when I couldn't get a pilot.

[Steve Helmick]

[quote author=Jim Kraft link=topic=61656.msg637817#msg637817 date=1653492983

Having said all of that, I have never run one personally. I have a Taifun Tornado 15 that is in super shape with a ball bearing crank. Never took the time to mix some fuel to run it. It was in a batch of other engines I bought. After watching the Brits run them kind of gives me the desire to get mine running.

On many of their small free flights they lower the compression to detune them for a slow climb out. Fun to watch.
[/quote]

The first diesel I ever had was a Taifun Tornado 2.5cc. I bench ran it some and flew it a few times...I was 15 years old. As I recall, it vibrated quite a bit. There is no counterbalance on the crank, just a full disc with the crankpin. I would suggest milling and/or grinding away the web on each side of the crank pin, but maybe Frank knows whether that's a good idea or not. If you (Jim) get to the point of flying your Taifun, I had a tendency to launch on the rich side, and diesels don't like that...so they stop.  Steve

[EddyR]

  Many years ago i ran Oliver Tigre .15 motors in FF models. They were not as loud as a a screaming glow motors.
I had to wear ear covering with the glow motors but not the diesel.
Ed

[Jim Carter]

     Hello All:

     Would somebody do a comparison between a glow engine with a muffler and the same engine converted to Diesel sans a muffler.  I would and could do it if I had access to a Db. meter. Anybody willing to loan or sell me a meter?  Perhaps a member would willing to perform this test and post the results here.

     I have several engines with DDD conversion heads and mufflers to use for making tests.

     Suggestions/comments

     Frank

Howdy Frank!  I have a meter that I can "loan" you ... just cover the round trip insurance and postage is all I ask. It's been good for our little group / club and helped solve a noise question a few years ago.  Where shall I send it?

Jim Carter
Titusville, FL

[Darryl Hawkins]

You can download an app on your phone for a dB meter.  I have dB Meter Pro on my phone.  It was a free app.