Originally Posted by
j lauria
A progress report on my 9-99 in my 87 in. 29 lb.Stearman. It flies the model very well. I am getting 5000 rpm with a 24X12 prop. It idles solidly at 1500 to 1800 rpm with or without glow support. It starts easily with electric starter in about 2 seconds with no choking. The top 5 cylinders reach temperarues of 125to 130 degrees F. The lower four cylinders reach 110 to 118 degrees F. These temps after running at 1/2 to 3/4 throttle for several minutes. I assume that this normal and they are all operating. On several occaisons when I have advanced to WOT from 1/2 throttle on the ground I reached only 4300 rpms. When that happened I reduced throttle to 1/4 and rapidly advanced to WOT and reached 5000 rpm. I am using on board glo support. I wonder if I lost a cylinder and then relighted it or am I loading up with fuel. So far following Maxam's advise on after run care using double the amount of air tool oil and Blue Blocker I have had no crunchie sounds.
J.Lauria, you should have plenty of power for your Stearman (like a 450 hp stearman), as my Stearman is 32 lbs. and flies very well on the 7-77 ( like a stock 220 hp Stearman) as my Corsair is 36 lbs and flies very well on the 9-99, but I am turning a 26x10 2 blade @ 52 to 5300 rpms I had the 24x12 and it was turning 56 to 5800 on the ground which in the air was over revving in my opinion so went with a larger diameter to slow it down and still have great performance. as for the temps on the cylinders after a little warming up I was getting 125 and up on the lower cyl. and higher temps. around 138 to 148 and some times a little higher on the upper cyl. for some reason, not sure if it is the way air comes in with the cowling or what but seems to run very well, I think if the temps are down in the 110 to 114 range then the plugs are not lit maybe due to the oil in the plugs, as in my case, at first I had to take the lower 2 cyl. plugs out to drain the oil that was in the plug coil itself then relight the plugs with my power panel and then reinstall the plugs and then they were fine and the temps were back up to the 125 or higher range, and was fine for the rest of the day. in my case the airplanes set level when not flying and after putting in the after run oil and sitting there until next flying session the oil goes to the bottom cyl. through the rings and fills the plugs up (I also turn the props through every day just to circulate the oil around the bearings), sooooo..... it is normal procedure to have to clean the plugs out before flying and I do not have any problems with temps. or cyl . not lit, but sure do love these radial engines I get a lot of talk at the flying shows and at the local field
-Steve