I have a new to me TopFlite Score with a like new Saito 56 installed in it. This is a former Crist Rigotti model that he sold a year ago or so that I missed out on, but recently purchased it from Leester who bought it from Crist. The model weighs 65 ounces and came with a Bolley 13/6 prop (which I have since ruined, a story not worth telling really), carbon fibre landing gear and Tom Morris controls. It looks like a really nice airplane with some good potential, I just have to learn four strokes.
Two years ago, while at the SIG contest, Keith Sandburg MADE me try his Legacy with a Saito 56 in it. He had the R/C carb on, set at about 3/4 throttle, and I think he had a Rev-Up 12/5 on it. HE fired it up, and boy what a sweet flying model. He said that once I tried four strokes, I would give up everything else! I don't know about that, but I was sure I wanted to duplicate what he had! Saito had just come out with the .62 a little while after that, so I bought one of those, but didn't have a model to put it in yet. I missed out on Crist's model the first time he had it for sale, but fate was kind to me and now it's mine!
The engine has the UHP venturi set up, and the Hoffman wedge style tank with 4 1/4 ounce capacity and I have line length of 68' from handle to model centerline. I flew it for the first time today, and the model does have a lot of promise, but like I said, just have to figure out these beasts now! I flew it with a Zinger Pro 13/6. Seemed like a lot of prop but I have been following the four stroke posts and know that they "like" a lot of prop load. I had no idea where to set the engine. These things REALLY are different, and by my tach and my ear, I thought I had it about right, and I had a 4.6 lap time race horse!! The engine run time was in the 8 minute range, so that at least mad me feel that the tank was big enough. I refueled (PowerMaster YS-20/20) and set the RPM at about 8000 RPM for this flight. The lap time was still a bit fast at 5 seconds, but at least I could try a few maneuvers and see how the model handled. The engine slowed a bit inverted, but not to any detriment, and the model has a pretty good corner. I did like the line tension everywhere I had, and can really see some potential. Then the engine ran out of fuel after only about 5 minutes of running. My concern is finding the right RPM and fuel consumption to avoid over runs or possibly loosing the model by having the engine quit at the wrong time!Trimming will be easy once I figure the engine out. I do have a few questions for you 4-stroke guys:
1) How critical is tank location as far as high and low? do I raise and lower the tank the same as for my ST.51's or any other s-stroke?
2) Can I go down to a 12/6 Zinger Pro, increase the RPM some again to slow the lap times down a bit more and help me get through the pattern on 4 1/4 ounces of fuel?
4) This is for Bob Reeves: I've searched out some of your posts on these engines and your method of using a nylon bolt to adjust the choke area of the venturi. In this model, the venturi angles back toward the firewall slightly, so installing one like I saw illustrated in one of your posts might not be practical. Can a smaller one be threaded into the side of the venturi to achieve the same desired affect? What size venturi would you recommend for this size and weight model?
5) I live in the St. Louis area at around 400 feet above sea level. What would the the suggested take off RPM with the set up I currently have installed in airplane?
I may or may not fly this model in competition. My main purpose for it is to use it as a mule to learn the natures of this beast, break in the .62 I have in the box, then build a new model for it later on. I do like what I have seen so far, even only the two or three flights I have on it. Thanks in advance for any and all help.
Type at you later,
Dan McEntee