Spent the last 3 days playing with and putting test flights on various Saito 40 Four Stroke configurations. Yesterday Joe Gilbert brought out his T-6 to add to the mix as we hadn't quite got there with it yet and needed to do a little more experimenting.
If you are interested in four strokes and haven't been following my trials and tribulations, this thread will give a little more insight into what prompted this latest go around.
http://stunthanger.com/smf/index.php?topic=10668.0A little more background.. I have really been satisfied with the way my Saito's run and most that have seen them have been pretty impressed with the power and consistency I'm getting out of these little valved wonders. One day we decided to see how one of my Saito 40's would stack up against the TT 36 Joe Gilbert was flying his T-6 with. We swapped out the TT for one of my Saito 40's and Joe flew it a couple times. The next day Joe ordered a Saito 40. BTW: The Saito bolted right up, mounting holes are the same. After Joe's Saito CL engine arrived and a little more experimenting I started the above thread.
Also I have a confession to make.. I have been preaching about my engines burning fuel thinking all along that if you fill a 4 ounce tank you are using close to 4 ounces... Well I noticed real quick that when I filled the tank using a syringe I could only stuff 3 1/2 ounces in it and when I fuel it from the pump on my flight box I don't fill it quite full. All this time I have been thinking I was using close to 4 ounces when according to the markings on a syringe it's really closer to 3.
What I wanted to accomplish over the last 3 days was... Using my setup as a base line I wanted to first see how the stock Saito CL engine (set up exactly as Saito recommends) compared to my engines and see if the new Brodak Y&O 11-6 could be made to work. The props I am using are Rev-Up 11-7's which are a bit hard to come by and I would really like to find a current production prop that works as well. We also wanted to see if the hard tank on the T-6 could be made to work as well as the clunk tank on the TwistMaster.
The two airplanes used for the test flights were my 8 year old TwistMaster and Joe's T-6 which was built by Don Hutchison. The engines were Joe's new CL 40 broken in properly and two of my Saito 40's one is a well used eBay RC engine that has who knows how much time but still runs great. The TwistMaster has a 4 ounce clunk tank and The T-6 has a hard tank that can be ran Uniflow or conventional vent.
First up was the stock Saito CL set up on the TwistMaster, I used 10-20 all synthetic fuel, the recommended 11-4 APC prop and started with the insert in the venturi. After a couple flights I removed the insert and ran it wide open. We then put this exact set up on the T-6 with the hard tank and ran it both with uniflow and standard venting. All flights were on muffler pressure with the needle valve set just on the rich side of peak RPM.
While the CL venturi was on the T-6 I went back to one of my modified RC carbs on the TwistMaster with the Brodak Y&O prop, PowerMaster YS 20-20 fuel and adjusted the choke screw for 8400 RPM to compensate for the reduced prop pitch.
After flying both the T-6 with the Stock Saito CL set up and the TwistMaster with the 11-6 prop we pulled the modified RC Carb off the TwistMaster and put it on the T-6 with a Rev-Up 11-7 and YS 20-20.
Yesterday was a pretty good day for this as the wind was blowing 12 to 15 MPH which would challenge most pilots and engines. No question, Joe and I both agreed along with our observer Tom Martin the best of the bunch was my original set up on the TwistMaster with the clunk tank. Joe is going to switch out the hard tank on the T-6 and keep the modified RC carb.
Please understand we are splitting hairs here. The stock Saito set up does work (without the insert) and so did the Brodak prop but we were not after "good enough" we were after "as good as it gets". I am now completely convinced the set up I developed with the help of Brad Walker, Doug Moon and Allan Perret two summers ago is as good as it gets.
The stock Saito CL set up with the insert in was.. well guess the best word to describe it is "wimpy", It just didn't have the drive and authority in the wingover and square 8 my set up does. Without the insert it was much better but still had issues with lap time speed up on a conventional tank (both clunk and hard) and sagging on uniflow.
The 11-6 prop with my set up was better than the stock Saito set up by a hair. It didn't speed up quite as much during the flight and didn't quite have the drive going over the top. It was a flyable set up that if I wasn't spoiled by what I have been use to I would probably be perfectly happy with.
Every since 4 strokes started appearing in CL circles most have discovered what we proved to ourselves yesterday.. Plastic RC tanks just work better than hard tanks. Joe's last flight yesterday was with the T-6 on a hard tank running muffler pressure non uniflow. It did run well but it burped on the down leg of the vertical 8 and quit when he did a loop toward the end of the tank (tank still had about 1/2 ounce of fuel).
Some of you will say the early quit was fine and on two strokes a cut off loop is part of the game. My thoughts are with a 4S we are only starting with around 3 ounces for the pattern and might be taking a big chance on it quitting early. We are pretty sure the burp in the vertical was the pick up tube being uncovered on the down leg which I have never seen happen with a clunk. As I said we are splitting hairs.. Yes a hard tank will work but.....
Where do we go from here....
First, it was about 75 deg with 40% humidity yesterday which (except for the wind) were pretty good conditions. This hasn't told us what the Stock Saito CL set up or an 11-6 prop will do on a 95+ degree Oklahoma or Texas day. I have a pretty good idea but can't really prove anything till next summer.
Sorry Saito you didn't quite make the mark with your recommended CL set up. I have the CL manifold off Joe's CL engine and plan on doing further testing and development. I am going to start by drilling out the spray bar hole to the same size as a PA (see the above link) and add my nylon screw choke adjust. If that doesn't work I'll try the spigot insert I made with the OS needle. I have no doubts I can get the CL manafold working as well as either my modified RC carb or my modified UHP just not sure which way I will need to go yet.
Sure wished I could talk John Brodak into adding an 11-7 to his Y&O prop line or even Eric Rule to his. The ones coming out now are really good looking props and I believe an 11-7 in either line would be as good as the Rev-Up. problem is I'm afraid to ask as I'm not sure how many they would actually sell.
I didn't credit Allan Perret in the previous thread for giving me the original idea of modifying the stock RC carb, couldn't remember his name and had to look it up in my old email archives.Thanks Allan..
Well know you know everything I do about the Saito 40 I have spilled my guts and hope this helps.. A few pictures would be good right....
Topic: Saito 40 CL Revisited (Read 2393 times)