Ok here's how it works

In normal mode the pitch goes from 0 (or slight negative) at 0 throttle position.
As you increase throttle stick, the pitch starts going to positive. 8-10 degrees positive at full throttle. At the same time its increasing motor RPM.

Normally you hover at around half throttle in normal mode. With the throttle stick at mid position if you flip the idle-up switch, the blade pitch should not change or the motor rpms. Once you flip the idle-up switch the heli locks the RPM's at a minimum of 50%. From mid stick to up is positive pitch, and from mid stick to down is negative pitch.

Think of it this way.

Normal mode adjusts head speed and collective together for positive pitch only.

Idle up mode locks the head speed and all you control is collective and the throttle curve adjusts throttle for both positive and negative pitch.

This might help explain it....hard to explain in words with out actually showing someone.


Normal mode.
Stick position: bottom / mid-stick / top
Pitch curve: 0 pitch / 4 deg + / 8 deg +
Throttle curve: 0 throttle / 50% throttle/ 100% throttle

Idle-Up Mode.
Stick position: Bottom / mid-stick/ top
Pitch curve: 8 deg - /4 deg +/8 deg +
Throttle curve: 100%/ 50%/100%

The reason for the +4deg at mid-stick during idle-up is because at 0 pitch, the helicopter would fall out of the sky. You still want to be able to hover at mid-stick even in idle-up mode.

Your perticular pitch levels may vary depending on how the heli was set-up originally, but this is just a "in general" example.

Most people use normal mode for hovering, and idle-up mode for forward flight.
Here's why.....

Say you were flying around in forward flight. Say you pull the helicopter into a fast straight line at level flight in normal mode. The helicopter starts to climb. What do you do. Most people pull off a little power. Now youve taken out pitch and RPM's. The helicopter starts to drop in altitude. Perhaps you over did it, and it drops too much. So you add more throttle. Its going to take a small amount of time for the rotor head to spool back up to speed to take advantage of the added pitch. There's a slight delay in the response. You'll find that alot of times flying in forward flight in normal mode...you either have too much or not enough and its difficult to maintain a constant altitude. This is even more noticeable on FP helis.

Say your flying a fast straight line at level flight in idle-up mode. You have the throttle at mid stick, so there is +4 deg of pitch and 50% throttle. The heli starts to climb. So you pull back a little. Now you have +1 deg pitch and 58% throttle. The heli starts to drop...perhaps a little to much. So you add a little. Because the rotor head is now spinning at 58% throttle instead of 50% throttle youve already got some good inertial speed in the head....ready for the increase in pitch. The pitch goes back to +4. Instantaneously youve got more lift. No delay because it already had the head speed it needed for the increase in pitch with out having to spool it back up. Also because eventually the rotor head speed will return to 50% there's no porporsing or jump up.

If you start flying in idle-up mode, you will actually find a spot in fast forward flight where the heli is moving forward, nose pitched down slightly, and you actually have 0 pitch in the blades, good head speed, and the heli wont drop out of the air, and will actually speed up forward airspeed because the blades arent providing any resistance. Kinda hard to explain until you notice it yourself. Its almost as if the rotor disk becomes a solid wing, and provides lift like a flat foamy airplane or something.

Helicopters are very interesting machines. In all reality based on physics, they arent even supposed to be able to fly. Kinda of interesting thought....Everytime you fly a heli you are disobeying the laws of physics. Ive flown airplanes for years, learning helicopters has totally made me reconsider how I think about aerodynamics. They seem to break every logical or common sense thing you would normally expect from something that flys. You have to think outside the box with these things. Just when you think you understand them, something new pops up that totally messes with your head.

Im still observing and noticing things everytime I fly that completely amaze me. I love flying these things. Its an addiction with me. All I think about is FLY FLY FLY FLY...new plane....FLY FLY FLY....new heli...FLY FLY FLY....

I need RCMA (RC modelers anonymous)...I think I need help.