I know that I have read this somewhere, but I could not find it again. I was wondering if anyone knows why a gas engine would seem to loose a little power during K.E. flight. My engine is a Brillelli 40cc with velocity stack. IT seems like it gets worse the higher the nose is during the K.E. flight. Straight K.E. is not bod, just the high alfa K.E.

Thanks you,

Travis

Travis,

It sounds as though the airflow into the cowl is changing the fuel mixture (leaning it). You may want to try removing the velocity stack.

The other thing it could be is the velocity stack is to close to the inside of the cowl. I had this happen on a Cap. It would change in KE in either direction. Again I removed the stack and all was well

My 3W 100 has done this from time to time. I think it gets better when the HS needle valve is leaned out more. I tried putting a tube from the carburetor regulator running into the fuselage and also into an intake snorkel. These efforts did not help, but leaning the high end seemed to help.

I put a RCBlimpPro carb plate over the reg hole on my carb and it made a world of difference... just depends on setup I guess.

Well, the thing is, my velocity stack protrudes out of the cowl. My motor is still a little rich on the low end so leaning that out some may help. I do have a pressure line running into my fuse. I am not familiar with the RCBlimpPro carb plate. I will do some research on it.

It does seem to be worse when I am doing a left-wing-down KE. Maybe it is the way the air is flowing over the cowling at high alpha KE.

Thanks for all the input though. Between ya'lls help and me fiddeling with it, I am sure it will get straightened out.

Travis

Travis,

If you have the line running from the cover plate into the fuselage, then the carb plate will not do much, if any good, it is basically doing the exact same thing which is to stop direct airflow over the hole in the plate. Now that we have a bit more info on the needle and stack locations, I would try leaning it a bit, then if that does not settle it down, remove the stack.

My issue only happened at about one third throttle. At higher throttle levels it ran solid regardless of knife edge, level or inverted. But at low throttle, it would richen up in certain attitudes. Lot's of gurgling. Leaning out the HIGH end seems to help.

I will lean out the low end a little on the ground until it runs smooth at all throttle settings. If it gurgels at low throttle in the air after that, then sould I lean the low end just a tad more, or go ahead and remove the stack?

Thanks again for all the help everyone,

Travis