Cyclic Hardover

My Feedback: (3)

Gas, 2 Stroke and 4 Stroke's have 3 very distinctive different sounds. No argument here. Lets say a fullscale Cessna 180 something or some smaller low winger cruises on by. Listening to the sound of the average plane, seems to me our 4 strokes sound more like one of these than the gassers?

Opinon here?

longdan

Most gas engines are 2 strokes, which as you said have their own sound, while the full scale aircraft are 4 strokes, so the 4 stroke glow engines probably do sound closer to the real thing than a gasser. Also with a 4 stroke you only hear half the number of revs that the engine is doing compared to a 2 stroke, so the pitch of the sound is closer to what you would expect to hear from a full scale plane.
A cessna would be cruising around 3000 rpm?, so the sound has a frequency of around 3 kHz. A 4 stroke glow doing about
9-10 thousand has a frequency of around 4.5-5 kHz. This is much closer than a 2 stroke gasser or glow where the sound is around the same frequency as the rpm.
I may be completely wrong, and haven't allowed for things like number of cylinders, tuned pipes, or lack of any mufflers at all. This is just my opinion.

NM2K

My Feedback: (14)

If you want your model to sound just like a full scale light plane that utilizes a four-stroke, opposed cylinder, layout, you need to use that same type of engine in your model.

The OS 3.20 Pegasus will provide "precisely" the same sound, because it is, essentially, the same engine.


Ed Cregger

Harry Lagman

I can't stand the sound of gassers. To be honest, it''s the main thing that quenches my enthusiasm for them.

I love their convenience, reliability, economy, cleanliness and ease of use but I hate the sound. Their sound reminds me of a crappy old Victa lawnmower (only Australasians can relate to this - apologies to the rest of you).

Give me a full length tuned pipe two-stroke or a straight piped four-stroke glow engine anytime.

blw

My Feedback: (3)

We have a couple of gassers at the field that sound good. I think they are running a little rich which makes them sound even better.

Kmot

My Feedback: (24)

This is a highly subjective question. That said, I think the typical gasser sounds bloody awful, annoying, and totally unrealistic in a model plane.

The first choice for me, for sound quality, is a four stroke. But there are many two stroke glow engines that sound very nice as well.

blw

My Feedback: (3)

Agreed. We fly out in the country, so noise isn't a factor.

I like the sound of a Saito .56. Very distinctive.

There is a Rossi with a pipe that sounds very good too.

scratchonly

The cessna has 4 cylinders firing every second stroke, so the frequency is 6000. A four stroke @ 12k would have the same freqency. I think?

Red B.

Here are links to one movie clip featuring a Swedish Grumman Bearcat with a Moki 250 5-cylinder radial gas engine.
Of course "scale sound" doesn't exist, but IMHO the sound of this engine is really nice :-).

[link=http://www.junkshop.nu/flyg/soderhamn_20070720/bearcat_small.wmv]Bearcat (11 MB, low res.)[/link]
[link=http://www.junkshop.nu/flyg/soderhamn_20070720/bearcat_big.wmv]Bearcat (49 MB, high res.)[/link]

/Red B.

P.S. Unfortunately I am neither the proud owner/pilot of this aircraft, nor the photographer. D.S.

Kmot

My Feedback: (24)

Oh, that Bearcat is lovely. Thank you for the link.

blw

My Feedback: (3)

Nice video. The engine sounds even better in real life. They are 4 strokes.

Bone

And no shortage of power either. Very impressive !!!

lucien

Well, gassers don't sound much worse than my full scale, which is one of these:

http://www.youtube.com/watch?v=0bjd38jvHWk

Mine has a different prop and gearbox, but this one and I have the same engine (Rotax 503 2cyl 2 stroke), so the scream from the motor is the same...

The muffler is a large tuned exhaust, though, which doesn't have the "braap" of those little can mufflers on the average gasser.....



LS

Harry Lagman

Red B, thanks for sharing that video.

Now that is an impressive sounding (and performing) model aircraft. That really made my day!

DarZeelon

The sound a piston engine makes depends not only on the frequency of the exhaust pulses, but on the number of cylinders and how their exhausts are connected....

Most O-200, O-320, VW Beatle and other flat-four engines, turning similar RPM, will make a similar note.

Most O-520, O-360 and O-540, Porsche Carrera (flat sixes) will also sound similar.

Different radials make different sounds too.


None of the above will make a sound that even remotely resembles a single cylinder four-stroke engine, model or other, at any RPM!