rickc2009,

you are experiencing a very normal condition in helicopters called blade flapback.

I assume you understand the very basics of helicopters, that the spinning blades form a rotory wing (or disc). Any rotating mass has gyroscopic forces, from a spinning top, to a bycicle tyre, to the rotory wing (helicopter).

If you appy a force to a spinning mass (gyro) the reaction occurs at 90 degrees to the applied force.

I'll use pitching up = aft cyclic = aft elevator in the example

Heres what happens -

- We want the helicopter to pitch nose up.
- we apply aft cyclic elevator.
- the servos drive the swashplate and tilt the swashplate aft.
- the blades actually lag the swashplate by 90 degrees because the pitch links are at 90 degrees to the blades.
- the blades subsequently reach the highest amount of pitch 90 behind the swashplates maximum tilt, at the 3 O'clock position (12 oclock is nose/6 oclock is tail)

- at this stage you might want to see this for yourself, by spinning the disc by hand, keep the flybar level, and watch the blade pitch change through one revolution while applying aft cyclic.

-so, as the blades reach maximum pitch at 3 oclock, we are effectively trying to tilt the whole disc to the left side.
- as the disc is a spinning mass, or gyro itself, tilting the disc left results in pitch up changes. (90 degrees from the left tilt=pitch up)

-if you tilt the disc right, the nose pitches down.

Thats all normal aerodynamic physics.

Now the condition we all experience when gaining airspeed and resulting in an automatic pitch up condition is explained as follows.

Lets assume the blades are rotating at 100mph.
When hovering the lift generated by the disc is even at all clock angles.
When moving forward say at 50 mph, there is an advancing blade (on the left side of the caliber) and a retreating blade (on the right side of the caliber)

The advancing blade will be moving through the air at 150 mph.
The retreating blade will be moving through the air at 50 mph.

This of course will cause the advancing (left side of the caliber) blade to generate more lift than the retreating blade. This will try to tilt the disc left, the subsequent reaction is for the nose to pitch up (same as a commanded aft cyclic described above)

Before you ask, helicopters can suffer from whats known as retreating blade stall if they exceed the airspeed limitations. (not normally encountered in RC)

hope this helps, its easy to explain standing besides someone with a model handy - more difficult in writing.