3D pitch ranges

I’m often asked what the best pitch range is for 3D. Kind of a preference thing, but in my opinion it’s the most pitch you can manage. At first glance many of the helicopters flown by the pros look unboggable, or seem as if they have an infinite amount of power. Unfortunately, that’s not the case. Today’s competition models do have a significant power to weight ratio, but not as great as some people think. All said and done, a 90 class helicopter is still easily over-tasked at times… if setup that way.

There are two kinds of pitch - cyclic and collective. Collective pitch is the correlation of both main blades increasing or decreasing in pitch together (collectively). This action makes the helicopter rise or fall. The more collective pitch that is applied the faster the model will climb (to a point). By using too much pitch you can load the motor down excessively… so much that the climb rate will become slower (once the head speed drops significantly) rather than quicker. I set my collective pitch for the best maximum climb both up-right and inverted. My 90’s pull about +12/-12 or +13/-13 depending on the day (temperature/humidity). My 50 will pull about +11/-11, and my 30 is setup with +10/-10.

Cyclic pitch is what controls your “elevator” and “aileron” commands. In heli terms, fore/aft and roll cyclic commands. This is a little more difficult to explain due to the relationship between the flybar and main blades. Different helicopters employ different flybar ratios and different paddle throws for a given cyclic pitch blade angle… that’s a different topic all together. Most helis are happy with 6 to 8 degrees of cyclic pitch. I prefer to max out the swashplate so there is no binding in the corners (full roll and fore/aft), and then tune my cyclic rate using different paddles and flybar setups.

Lets use a 90 class helicopter as an example. Today’s .91 motors make some awesome power, and we can set the model up to be nearly unboggable if we choose. However, with this type of setup you’re going to have a slow climb rate and a sluggish cyclic feel… not nearly as lively as you’d want for aggressive 3D. You’ll be able to mash the sticks as hard and as uncoordinated as you want and the motor will still haul through it… but again, the model probably wont be as snappy as you’d like. Consequently, this is not an ideal 3D setup. For hardcore 3D we want the model to have plenty of authority. To achieve this we have to run quite a bit of both cyclic and collective pitch. I personally like to come close to reaching the motors limit in a straight up, vertical climb. This requires anywhere from 12 to 13 (I’ve flown some helis with 14) degrees of pitch. With such a hefty blade angle the model will climb like bat from hell! With that said, you have to remember that you’re using up almost all of the motor’s power to get such a snappy and crazy collective feel. When at full collective pitch you will only be able to use full cyclic commands for short periods of time, otherwise you will over-task the motor. This type of setup requires the pilot to have more finesse and collective management. The end result is a helicopter that can switch directions extremely quick and flip/roll rapidly with a very “light” feel. Once you get used to this type of setup it will definitely benefit your flying. Starts and stops can be made much quicker and collective pumps look more impressive and powerful. This type of setup may not be for everyone, but it’s worth trying for sure.

Use as much pitch as you can manage on any model, collective managment is a skill in itself... but once you've got the hang of it you can make a heli look way more powerful than the untrained spectator or flier thinks.

Hopefully this helps some of you,

Colin

THANKS I,m just about ready to get into .90 sized helis, and I realy needed that

That was a great post, very informative!

Is there a special tool thats needed to see what your cyclic pitch is

Mavrick- just use a standard pitch gauge on the main blades as you would to check the collective pitch.

-Center your throttle/pitch stick and make sure you are at zero degrees.
-Rotate the rotor head so that the blades are either aligned with the tail boom or at 90 degrees to it. (doesn't matter for now)
-Now add full aile or elev. Which ever changes the pitch of the blades is what you will be measuring.
-Level the flybar with the given cyclic input and record the pitch measurement. That is your cyclic pitch.
-Repeat this for the opposite direction of cyclic input. Rotate the head 90 degrees and measure for the other cyclic input.
-That is it !

Its also a good time to check your phasing. If you position your flybar left to right across the heli and give it elevator input your blade grips shouldn't move at all. If they do move (make sure you aren't giving aileron input) then the phasing is out. This will cause things such as uneven rolls and for the heli to pull left or right if you flip it.

To fix it, simply losen the washout (that thing with the two guide pins) and rotate it slightly one way or the other until you have no movement on your blade grips when giving elevator input. Once you've found the sweet spot, just tighten it back up and you are good to go.

OK thanks guys.

[Sean Sullivan]

Colin I hope you don't mind but I'm going to E-mail your post to a few friends, mabye you're explanation will get through to them.