Support

FA-125A AAC with Muffler: AG

Well, here we go again! With this new Saito engine, it isn’t a question of whether it makes more power than the FA-100 that it came from, but rather how can it be 10 ounces lighter than the current FA-120 (large case) engine that it has to live up to? Side by side, it looks like it just can’t be!

It’s true! With the APC 16x6 prop, the Saito FA-125a is singing at 9000 rpm using standard 15% nitro content fuel. The initial flight-testing was performed in the tried and true, do it all, Hangar 9 Ultra Stick Lite. This model has been powered by everything from an Evolution 100 glow engine to Saito 180, and even 220a engines as well as a couple of Evolution Gas 26cc engines along the way. With most of the larger engines, the model ends up nose heavy and requires additional weight in the tail to balance properly. With the FA-125a, the balance is finally back where it belongs!

But first, some background. The Saito company must have roots in the American auto Hot Rod enthusiasts’ formula of boring and stroking engines to increase displacement. Existing engines like the FA-50 became the FA-56, the FA-72 became the FA-82 and the FA-120 eventually was increased all the way to an FA-180. All have been successful and so the same formula was applied to the FA-100 resulting in a displacement of 1.25 cubic inches. But the surprise comes when it is compared to the current FA-120, which has served modelers very well for a number of years. The FA-125a is much smaller externally and the difference in weight of 10 ounces, roughly one-third less, gives a wonderful power-to-weight ratio! Prop speed and size is basically the same as the
FA-120.

It is recommended that you follow the break-in procedure in the manual before flying your model with the FA-125a for the first time. Start-up using the tried and true method used on all the Saito 4-stroke engines results in first flip starts every time.

A)  Fill the fuel tank

B) Make sure the fuel feed and muffler pressure lines are hooked up correctly

C) Put your finger over the exhaust outlet, open the carb, turn the prop through two compression strokes, close the carb to idle position

D) Hook up the glow power and flip the prop backwards against the compression.

The Saito will fire off first try.

Now at the flying field this thing is impressive! Keep the needle a bit rich for a few flights to assure that you do not overheat the engine.

Even with the slightly rich settings, the FA-125a just “jerks” the Ultra Stick off the ground when you punch full throttle; pull back on the elevator and it just keeps going! Ok, so it climbs—how about an extended spin cycle back to low altitude at idle, 17, 18, 19, 20 turns—yikes, pull out! Engine is still idling at 1800 all the way to the bottom and recovers to full throttle with no roughness or missing at all. Right away it becomes apparent that the FA-125a has response to throttle settings we have all been looking for- very linear and each click off of idle results in a small rpm change. With this kind of throttle response the model responds sooo nicely in hover and harrier maneuvers or while doing tail wheel only touch and goes.

One other aspect that keeps everyone happy, but is not usually associated with performance testing, is the level of sound that this engine does not generate! We noticed on the first flight that it was quiet. You just can’t hear the engine run when other models are in the air. Everyone watching has the same observation, “You can’t hear it run in the air.” It is remarkable, and I am sure this will also be a welcome aspect at the local R/C flying field.

Fuel consumption is very reasonable and the standard tank in the Ultra Stick might be judged to be larger than necessary, but flying this combination is enough fun that extended flights become the norm. And of course, all of your friends want a bit of time on the sticks as well, so a little extra fuel can’t hurt.

This Saito seems to be a real R/C flyer’s dream; it will power just about any kind of model and keeps on ticking, ready for more. Easy to mount, easy to run, easy (and reliable) to fly with huge power! If you purchase this Saito you just might not have time for some of the other engines that get left at home! Here is one with lots of built-in FUN.

JEB