Webra Thread .... clipped to accommodate list length

[Jim_Woodward at beaerospace.com]

Hi Emory,

Going to Apopka?  Good question.  Pump pressure and mixture go 
hand-n-hand.  If the engine is rich in the midrange on the ground, but 
exhibits symptoms such as:  popping sounds or puffs of smoke when adding 
power, moments of silence then catch at full rpm, or does not sustain 
power on uplines - you need more pump pressure, then readjust the carb for 
good ground running.  Reducing pump pressure may yield a good ground 
running, but it might not yield sustained power on uplines.  I run as much 
pump pressure as possible, while maintaining control over the fuel 
metering in the carburetor.  "Shamless plug" - thats the beauty of the MC 
carb.  You can run a lot of pump pressure, and just bias the control arm 
adjustment a little on the on the carb, then use your transmitter to tune 
the rest of the throttle-mixture curve.  This way, you always have enough 
pump pressure.  The real test of the MC carb is in-flight performance.  If 
there are any dead spots, just note about where the throttle stick was, go 
into the program, and richen or lean in just that area.  For instance, you 
can leave the idle fairly rich, so the engine slows down right away when 
you reduce throttle to idle, but if you lean a couple points just above it 
you get instant "zippy" throttle response, then make the top point a 
little rich to control the top rpm figure.  Once you get the right mixture 
everywhere you want it, use the transmitters actual "throttle-curve" to 
set the amount of power you want for a given stick position.  Use this 
feature get the right velocity for the throttle stick position you usually 
fly.  I think I fly mostly around the 5/8-3/4" throttle stick position. My 
throtte curve is steep at first to give some prop blast over the rudder 
for stall turns, then flattens out quite a bit - barely rising.  The last 
two & three points of the curve rise very steeply - like a very 
smooooooooth switch!  Thus, I get 'full' power only at the last two & 
three positions of stick movement.  The best part is that as soon as you 
get back off those top 2 or 3 throttle stick points, the engines rpm has 
really dropped - instant speed mangement while keeping the throttle stick 
in the position I like to maneuver in!  Finaly, mix the throttle curve to 
a knob near the throttle stick, you can adjust the rpm while in flight 
(although the knob affects the entire curve).  There is a learning curve, 
but the overall action is superior.
Jim w.

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.f3a.us/pipermail/nsrca-discussion/attachments/20040802/06177c7e/attachment.html