It looks like the 72 (not made any more) is about 2 ounces heavier than the 62 (currently made). There must be some people with experience using either of these two motors on a 60-size stunter (60 inch wingspan with around 679 square inches), and could give their opinion if the 62 has enough power for this size plane. I read that the 72 is a BEAST and is run at less than full power. If that is the case, I'd rather get the 62 and run it closer to full power and save the 2 ounces on the nose.
Hi Russell;
Have you ever run a four stroke engine before? Do you already fly C/L stunt? I have a Top Flite Score that is about the size that you are looking at, and it is powered by a Saito.56. This is a pretty nice combination, and it was my introduction to operating and flying four strokes for C/L stunt. I messed with it for about 3 flying seasons, and got everything but what I wanted out of the airplane, so I put it aside. Then I read some stuff by Bob Reeves and another gentleman whose name escapes my now, and I figured out I had been approaching things the wrong way. I finally realized that even with as long as I have been flying stunt in competition (about 30 years at that point in time ) I needed to completely forget and disregard everything I knew about operating engines and props for flying stunt because it is completely different for a four stroke. It is a completely different kind of power, a kind of pulsing power, and you can not operate them like you would a two stroke. There two little things on them called push rods for the valves that just don't like to rev very high and won't take much abuse! I was lucky in that I was able to talk with Gilbert Berringer from France at the Oshkosh Air Venture Convention and he told me a bit about his set ups, and he was one of the first to really successfully fly four strokes on the F2B world. It's a very interesting type of power and I liked it once I got things figured out. Four strokes are all about fuel draw, and a good hot plug. I found that they do not like uniflow tanks, so just learn to set things so that your lap time gets a bit faster near the end, but it hasn't been much of a deal breaker for me. The Bob Reeves set up is a low RPM deal, and you use 6 and 7 inch pitch props, on occasion you can drop down to 5 inch pitch if the model is light enough, but that is difficult. What I found out from Bob Reeves and Gilbert Berringer is that you want as small a venturi that you can get. Berringer told me he generally runs about 6mm and smaller. Bob Reeves adapted the idea of adding a nylon screw to the venturi to adjust the choke area and in combination with the needle valve makes a set up that runs in the range of 8000 to 8500 RPM. And for fuel, I always run Powermaster YS-20-20 fuel, and use anywhere between 3.5 to 4 ounces for the pattern and muffler pressure is a must.. Props are 13-6 and 13-7. The Score weighs in around 70 or 71 ounces and the .56 handles it with ease and is more than enough for me. With a little adjustment I can make it pull your arm off but it won't fly a very good pattern that way! I like it to fly a 5.3 lap timeon about 65 foot lines and am pretty comfortable with it now and have done respectably well in contest with it in the Expert class. Like I said, I find it an interesting and fun powerplant, but I'm not selling my Supertiger's any time soon! I find ST.60s pretty interesting and fun for the same reason, but don't limit myself to those exclusively. If you have to build the model yet, I think you are on the right track in considering the Saito .62. It is pretty much the same size and weight as the .56 is. With the C/L version you get a choice of venturis I think, and can just start with the smallest one. I would spend as much time as you can reading this four stroke section on anything you can find about the Saito .56 and the .62. If you haven't run any four strokes before, it will be an eye opener for you. They are very quiet, just do not make much noise. If you have been flying two strokes for any length of time, you equate power with a certain type of noise and sound level in your mind, and you ain't gonna find that with a four stroke!! That is not to scare you off of them, just to prepare you for it. It's actually kind of neat. The engine does not break at all, but runs, when things are right, in a steady monotonous tone. The engine makes it's power from gobs of torque, and running the YS 20-20 fuel let you open the needle a lot so it gets the fuel it needs to make that power. With the Bob Reeves method, things are very adjustable. Go the the Glue Dobbers site and down load his stuff and study it and by the time you get the model built, you should have everything straight in your mind. I didn't fly any of my other two stroke models for as couple of years after I got mine squared away and never had a bad run during that time. I hung mine on the wall because the covering was starting to come off, and it needs a recover job, which it will get this winter, then back into some action next year. I am not familiar with the model you are building, but even with the Saito .62 or .56, I would consider shortening the nose a bit to compensate for the engine weight, if you think you need to. If it's intended for a tuned pip engine with ball bearings and such, you may want to compare the engine weights and figure from there if shortening the nose will be required. I would make sure that you still have room for a 6 ounce tank, just to be safe. Good luck with the model and have fun.
Type at you later,
Dan McEntee
Topic: Saito 62 vs Saito 72 (Read 7918 times)