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power system for 1978 duallist opinions?

Old 12-10-2014, 03:39 AM
  #26  
mred
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Yes, they were both standard rotation. It's a little hard to get a glow engine to run the other way. I guess I could have sent it back to K&B and ask them to change one, but I never felt that was necessary, so they just ran standard rotation. That's why it is worse to loose that left engine. You get to fight the torque and thrust on that right engine and both are trying to make it turn left. It was never such a problem that I felt I was getting into trouble with it as long as I kept my airspeed up.

I only came close to loosing it once, but I did that to see just exactly what would happen if I got to slow. When you finally run out of rudder and aileron, things get bad fast, but I also had enough height to recover with no problem, so I came in and landed. Had to get my knees to stop knocking before I could fly it again.

I wish you luck with yours and hopefully I will have one by at least the end of summer. I build kind of slow, but I get there sooner or later. Good luck with yours.
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Old 12-10-2014, 06:06 AM
  #27  
fhhuber
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Reversing many (all that I know of) K& B engines was accomplished by pulling the front of the case and turning it 180 deg to reverse the crank port timing. Works for any engine using the crankshaft as the intake valve where the front of the case can be unbolted from the section with the cylinder.
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Old 12-10-2014, 06:25 AM
  #28  
kyleservicetech
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Originally Posted by fhhuber View Post
Reversing many (all that I know of) K& B engines was accomplished by pulling the front of the case and turning it 180 deg to reverse the crank port timing. Works for any engine using the crankshaft as the intake valve where the front of the case can be unbolted from the section with the cylinder.

Out of curiosity, can those gasoline engines with reed valves run in reverse, assuming the crankshaft timing can be changed accordingly?
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Old 12-10-2014, 07:33 AM
  #29  
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For most of the reed valve gasoline engines all you have to do is change the ignition timing. Relocate the Hall sensor and it will work. The reed valve is operated on the vacuum in the crankcase when the piston rises to let in fuel/air mix and it is closed by the pressure of the piston moving down.

People have done this with no problems other than it being hard to find the reverse pitch prop.
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Old 12-10-2014, 11:17 PM
  #30  
walter3
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i have received my 3 blade 10x7 emp props. going to test them for amp and watt figures and then ill have 3 choices at hand. RESULTS.

master air screw - 110 watts/lb. counter rotate 10X7 3 BLADE - CLEARLY NEED MORE PITCH!

emp - 116watts/lb. standard rotate 10X7 3 BLADE - CLEARLY NEED MORE PITCH!

durafly - 160 watts/lb. standard rotate. 10X8 3 BLADE. POWER!

which would you use for maiden? my gut says go with the most power, but i don't want to hear.... i told you so from the peanut gallery if its an issue. most duallist owners use standard rotation. im tempted to just say screw it and go for it based on pilots that know this girl first hand. thoughts? IF ANYONE KNOWS OF 3 BLADE COUNTER ROTATE 10X8 PLEASE LET ME KNOW!!

Last edited by walter3; 12-11-2014 at 01:48 AM.
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Old 12-11-2014, 02:25 AM
  #31  
kyleservicetech
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Originally Posted by walter3 View Post
i have received my 3 blade 10x7 emp props. going to test them for amp and watt figures and then ill have 3 choices at hand. RESULTS.

master air screw - 110 watts/lb. counter rotate 10X7 3 BLADE - CLEARLY NEED MORE PITCH!

emp - 116watts/lb. standard rotate 10X7 3 BLADE - CLEARLY NEED MORE PITCH!

durafly - 160 watts/lb. standard rotate. 10X8 3 BLADE. POWER!

which would you use for maiden? my gut says go with the most power, but i don't want to hear.... i told you so from the peanut gallery if its an issue. most duallist owners use standard rotation. im tempted to just say screw it and go for it based on pilots that know this girl first hand. thoughts? IF ANYONE KNOWS OF 3 BLADE COUNTER ROTATE 10X8 PLEASE LET ME KNOW!!
I've been flying that TwinStar model with a pair of 600 Watt Hyperion motors up front. These motors are running at 450 Watts, turning their 10X7 APC-E props at 10,800 RPM.

After the maiden flights, the kit supplied spinners were installed. On the very next flight, something came off the model after a full power dive. Didn't know what happened, the model flew OK, but a bit sluggish. Landing was un-eventful. Found out during the taxi back that the entire motor shaft and prop of the left motor was missing, busted off at the front of the motor bearing.

Usually, when an engine on a twin quits, the model instantly rolls over and goes in.

So, I suspect that with your twin, both motors turning in the same direction would be OK.
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Old 12-11-2014, 01:05 PM
  #32  
walter3
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i have located a set of 10x8 COUNTER ROTATING props! there from durafly, like the high power standard ones i have. once they arrive ill balance and test them as well. hoping they put out some high numbers so i have powerful standard AND counter rotate options. Walt
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Old 01-29-2015, 11:28 AM
  #33  
Ronald86
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Originally Posted by walter3 View Post
i have a 10lb. auw 1978 pica duallist with power 32 770 kv motors with 75 amp esc on 4s 3600 batts. how many watts do i need to fly this well. i have multiple props, some standard some counter rotate. i have a watt meter. im getting around 110 watt per lb on one set and 160 watt per lb on another. will these both work? the 110 happen to be counter rotate, the other standard. both well under the amps for the esc even at wot. thoughts? thanks for the imput. walt
Beautiful plane
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