Quick test flight
On our trip to Sikeston this past weekend, KC Center couldn't pick up our transponder. It was working before. On our way back, I kept it tuned to the various center frequencies and heard them make a traffic call to another pilot that approximated our position and height, so it must have been working. So after work on Tuesday, I made a quick flight up the 5500ft and called KC Center to see if they could pick me up and sure enough, they got me. I'm hoping this doesn't become a gremlin.
I guess I should also update everyone on my induction system issues. Since Flight #1 I've had goofy mixture problems and what seemed to be fuel leaking from the carb. My static and WOT RPM's weren't really what they should have been either. I got a call from Dave down in Texas who also has an RV-9A with a SJ cowl/induction but he has an O-360 in his bird. After many phone calls and emails with some troubleshooting, we have discovered that the carb air box that Will James delivers with his cowl kit is very inefficient and in MY case is causing turbulence in the box. Enough so that it actually sucks fuel OUT of the carb, as evidenced with fuel stains in the throat of the carb and in the air box. My solution to the problem has been to replace the airbox that mounts to the bottom of the carb and replace it with a 3" flange to which I attached a 3" SCAT tube that connects to the filtered air box. This setup has eliminated my mixture problems, increased my static RPM by 100rpm getting me up to 2210rpm static. My WOT throttle RPM is now 2650, as before I could only get 2550 with the old air box. I could get 2610 with no airbox at all.
Suffice it to say that I am very pleased that the problem has been indentified and a solution is in place. Will is going to revamp his airbox and replace it with a 90-degree elbow of some sort, as this appears to be the best method of feeding air into the carb. I'll probably leave my setup as is for now. It sucked to go fly and always be questioning the engine.... now I am MUCH more confident/comfortable when I go flying.
Also, my elevator counter-balance arms are sticking up about 1/2"-3/4" during cruise flight. I think most builders leave it as is but it kind bugs me. So I made up a .016" shim and stuck under the front HS spar. That took out about 1/2 of what was sticking up. I'll put one more small piece under there to see if I can get the rest of it out. There is a posible side effect of running out of nose up trim though.
I guess I should also update everyone on my induction system issues. Since Flight #1 I've had goofy mixture problems and what seemed to be fuel leaking from the carb. My static and WOT RPM's weren't really what they should have been either. I got a call from Dave down in Texas who also has an RV-9A with a SJ cowl/induction but he has an O-360 in his bird. After many phone calls and emails with some troubleshooting, we have discovered that the carb air box that Will James delivers with his cowl kit is very inefficient and in MY case is causing turbulence in the box. Enough so that it actually sucks fuel OUT of the carb, as evidenced with fuel stains in the throat of the carb and in the air box. My solution to the problem has been to replace the airbox that mounts to the bottom of the carb and replace it with a 3" flange to which I attached a 3" SCAT tube that connects to the filtered air box. This setup has eliminated my mixture problems, increased my static RPM by 100rpm getting me up to 2210rpm static. My WOT throttle RPM is now 2650, as before I could only get 2550 with the old air box. I could get 2610 with no airbox at all.
Suffice it to say that I am very pleased that the problem has been indentified and a solution is in place. Will is going to revamp his airbox and replace it with a 90-degree elbow of some sort, as this appears to be the best method of feeding air into the carb. I'll probably leave my setup as is for now. It sucked to go fly and always be questioning the engine.... now I am MUCH more confident/comfortable when I go flying.
Also, my elevator counter-balance arms are sticking up about 1/2"-3/4" during cruise flight. I think most builders leave it as is but it kind bugs me. So I made up a .016" shim and stuck under the front HS spar. That took out about 1/2 of what was sticking up. I'll put one more small piece under there to see if I can get the rest of it out. There is a posible side effect of running out of nose up trim though.
posted by Matthew at 4:53 PM
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