Engine basics > Four strokes only
Saito FA-82B ???
Dennis Toth:
Seems that you just need to build a solid nose like we did for the ST60,with solid maple (3/8 x 5/8) mounts and cross grain balsa between them with at least 1/16" plywood doubles, a solid box construction of the main fuse with good blocks for the top and bottom. We did (still do) this type of nose construction for the Foxes too and it works fine.
Best, DennisT
spare_parts:
The torque produced during the power stroke in a four stroke is necessarily much greater than a two stroke. The negative torque during compression is also greater. I think this is often observed as vibration. I mean it is, but torsional. With aluminum pistons, most fourstrokes are balanced well in this sense. How it all works with airframe resonance is anyone's guess. Saito were very popular on profile fuselage RC models.
It's quite possible that a small difference in construction, prop, or RPM sets up an unhealthy resonance, but the chance of conditions coming together for actual failure is quite small.
Claudio Chacon:
Hello guys,
I can attest, with absolute certainty, that the SAITO FA 72 is a PERFECT engine for CLPA.
I've been (and still am...) using this engine for years.
The alleged excessive vibrations that this engine produces, are just a myth...believe me...it vibrates, yes, but NOT more than any other engine.
Just keep your props well balanced and you'll have a great reliable and competitive engine.
Later,
Claudio.
Claudio Chacon:
Hi again,
What follows are some pics on how I built the noses of the planes you see in my previous post.
Nothing special, just a solid construction...
Claudio.
Robert Zambelli:
Well said, Claudio!!!
As previous mentioned, I've been a proponent of four cycle engines for around 25 years.
I've used nearly every brand and size up to the .90 and vibration was never an issue - neither in profile or full fuselage applications.
This anti-4S CRAP started many years ago when someone armed with nothing more than monumental ignorance posted an article all but condemning our great 4S powerplants. I don't know if he ever even used or flew one. Surprisinlg, a number of people actually believed the BS he was troweling out.
Some of the great pilots that I knew while working in Italy - Campostella, Cappi, Maggi and Semoli along with the Berringers from France worked absolute magic with these wonderful engines.
Just my 2 cents!!!
Bob Z.
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