Andreas: I have been flying 4S motors for several years now, and really like
the way they perform. For the last 3 years I have used the OS 52 FS in my
60 oz. Saturn with an Eather 3 blade (blue) 13 x 4 prop that has been cut
down to 11.75" and repitched out to 6 at the tips by the pitchman: Brad Walker.
This is a great combo and I have done my best flying with this setup.
I have also used the Saito 40, 56, and 72 motors. For 60 size or larger ships
I actually preferred the 56 over the 72. It seemed to me to be an easier to engine to find
the 'sweet spot'. With the 56 I used a Bolly 13 x 6 2 blade prop. I've also had
good success with wood props on the Saitos.
I use the Ultra Hobby Products manifold/venturi conversion that was originally
designed by Pat Johnston. This replaces the carburetor with a manifold. You then
insert a venturi into the manifold and a needle valve assembly. I use OS NVAs, and
have had good luck with both spray bar and spigot type assemblys.
I've also run the 4S motors with the carb. wired open, but have had better luck
with a man/ven conversion. I never seemed to get quite as steady a run with the
carb wired open. The barrel in the carb would tend to vibrate just a little bit, no
matter how securely I had it wired open. I'm not saying the results were poor, I just
seem to have better luck with the conversion kits.
When running a 4S motor in CL Stunt you want to be sure to keep the motor in it's
optimum power band. You will need to use a big enough prop with enough pitch so
that the motor is not over-revved and past the power band. My needle setting is
usually just a few 'clicks' below wide open. This way the motor is making plenty of
power but won't go 'over the top' and begin to sag.
Also, once you find a good prop/needle setting combo 4S motors require very little fiddling.
This season I got the Saturn out for the first time in April and got a few flights in
to get the rust off the ol' flyin' arm. Once I found a good needle setting I put in a couple
of more practice sessions, flew in the Texarkana contest, flew in the Houston contest
3 weeks later and put in another practice session without touching the needle once.
I finally had to adjust it this weekend as the weather has gotten hot (90+) and muggy
here in TX. I turned it out 2 clicks and probably won't have to touch it again until the
Nats. The 4S are also very economical, I am using 3.5 oz. of Powermaster 20/20 4S fule
per flight. I can get about 35 flights out of one gallon of fuel.
Hope this helps, and good luck, Steve
Topic: 4-stroke question (Read 2849 times)
