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Engine basics => Engine set up tips => Topic started by: Paul Allen on May 12, 2007, 05:20:34 AM
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I have some questions on pipe runs,have a Magnum 36
with a 40 pipe( Randy's) in an Oriental and notice the lap
time at the start of the flight is 5.1 sec;s and at the end it
drops to 5.4 sec's, when the motor is tached it cycle's from
10,400rpm to 10,700rpm motor sounds like its just into 2cycle
after take off it settles back with a little crackle in the run.
I do not want to go in on the needle any more ,if I move the
pipe in a bit would that stop the riching up effect at the back
half of the flight.Prop is a Master Airscrew 11 x 5 which when
checked on the pitch gauge is 3.75, tried a 11x4 wood prop but
the plane did not turn well with it ,yet the Master Airscrew works
well.
Are there any others using the Magnum on pipe?
Thanks.
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Sounds like the plumbing in the tank. A uniflow tank is supposed to keep the engine from leaning out too much in the last half of the pattern, maybe the tubes are a "little" off? I have been hearing of people checking their tanks and the tubes have been soldered up a little off. ??? ??? ???
Not sure that the length of the pipe would affect what you're describing, but Randy can tell us for sure! (oh where oh where are you Randy??) ;D
Bill <><
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I have some questions on pipe runs,have a Magnum 36
with a 40 pipe( Randy's) in an Oriental and notice the lap
time at the start of the flight is 5.1 sec;s and at the end it
drops to 5.4 sec's, when the motor is tached it cycle's from
10,400rpm to 10,700rpm motor sounds like its just into 2cycle
after take off it settles back with a little crackle in the run.
I do not want to go in on the needle any more ,if I move the
pipe in a bit would that stop the riching up effect at the back
half of the flight.Prop is a Master Airscrew 11 x 5 which when
checked on the pitch gauge is 3.75, tried a 11x4 wood prop but
the plane did not turn well with it ,yet the Master Airscrew works
well.
Are there any others using the Magnum on pipe?
Thanks.
Hi Paul
What type fuel tank setup are you using?
pipe lenght?
Randy
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Lotsa .36's on the pipe! I have two (Randy's) on the pipe, and one 1/2 (Randy's) off the pipe!
Do what he tells you! They're fabulous...(Actually the Aero Tiger is a PA .36!)
Oh, mine are the square head Magnums and Thunder (Aero) Tigers.
Ward
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Randy,
4 oz uniflow wedge tank,uniflow open to airstream
pipe length 17'' from plug to first baffle.
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Randy,
4 oz uniflow wedge tank,uniflow open to airstream
pipe length 17'' from plug to first baffle.
HI Paul
The first 2 things I would try is , first fly the plane with the overflow open and the uniflow capped off, This will tell you if there is something in the tank doing this, The described is normally most always a Tank or fuel delivery problem, second thing is heat or vibration.
If your plane doesn't slow down thru the flight with the uniflow capped. It would be just a replumb of the fuel tank needed.
If you shorten the pipe to 16 3\4 that may help a tenth, but you will not get more than that.
Is the motor in a rich 2 cycle or 4 cycle throughout the whole flight?
Randy
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Randy
Will try capping uniflow vent,motor runs through
flight in 4 cycle,I may not have been clear on this, I used
the term it had a " crackle " to it in flight,on the ground
its in 2 cycle, once in the air it settles into 4 cycle.
Should I be seeing a 300 rpm variation on the tacho,I thought
it may be more stable then that.
Will report back on tank capping, maybe a week before I can
post on the forum again.
Thanks
Paul
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Paul I ran a Magnum 36xl with pipe and I found that a 16 7/8" pipe with a 3 blade Bill Lee 11x4 work well with a soft 2 cycle about 10.5 - 11 K RPM work well with my Oriental. I had lap times between 5.0 - 5.5 on 65' lines and 10% fuel and Aero one .As I remember Phil Granderson runs his fast 2cycle on his Diva . ::) y1