Pitch Curves
All collective pitch helicopters have them. Whether you can program them into your transmitter depends on which helicopter you own. With say a Trex, you will be programming the curves in yourself. With an ESKY KING or CP2, the curves are pre-programmed into your transmitter and other than a small adjustment via the pitch knob - you can't touch them.
So what are they ?? The pitch curves are a way of telling your helicopter what pitch should be on the blades at what collective stick position. With your collective stick right up (high) the curve should be telling your helicopter that you want maximum pitch on your blades, because you want to go up fast if your stick is in that position !!! The same when you shut your helicopter down to stop, you don't want any pitch on the blades (or very little, say -2). Again, it is the pitch curve that tells the helicopter this.
The most common type of pitch curve is a 5 point curve. This basically means that the curve is made up of 5 points, 1 at low stick, 2 at quater stick, 3 at mid stick, 4 at three quarter stick and lastly 5 at high stick. When you program your curve into your transmitter you are telling it what value these 5 points should be as a percentage of total travel. Now this is where it gets a little interesting and where newbee's can become a little unstuck. The total travel is the entire pitch range of your blades and this includes the -ve bit too !! So, an average RC helicopters pitch range will be from -10 to +10 degrees, a total range of 20 degrees. So those 20 degrees are in exact relation to your 100 % (remember you pitch curve points are programmed in as a percentage).
So Collective stick High. Easy one to start with. Stick right up is point 5 on the curve. You want maximum pitch ( +10 degrees), so it has to be 100 % programmed into point 5 on your curve.
Mid stick next. You dont want any pitch on your blades here. Tap in 0 % for your curve. WRONG !!!. This is the mistake that many people make when they first try to program their pitch curves. Remember that the percentage scale relates to the total travel of the blades - all 20 degrees, so therefor 0 % must be -10 degrees pitch. So, back to mid collective, right in the middle, of course it has to be 50 %.
Getting the idea now ?? It isn't hard, just a few ratio's thats all. 
So now you know this, have a look at the first picture. It will help it stick in your memory a little better.
Right, this is what is called a linear curve as the curve is well, a line.
If you look along the bottom line, this is your collective position, right from low stick to high stick. On the left you have the pitch on the blades, from -10 right through to +10. And straight across the middle you can see 5 points. These are the points you program in your Tx.
Now we have looked at high and low, lets look at the point in between, but using the picture this time.
Right, lets program point 4. Find point 4 on the picture and then follow it straight up until you reach the curve. Then follow the blue line to the right. You will come to 75 %. This is the figure you need to program into your Tx. If you follow the green line to the left you will see it will give you 5 degrees pitch. It makes sense if you think about it. Point 4 is right in the middle of point 3 and point 5. Now if point 5 is 100 % and the mid point 3 is 50 % then between the two has to be 75 % - basic maths. The same for the pitch, point 5 is maximum +ve pitch of +10 degrees. Point 3 is mid collective (right in the middle of the range -10 to +10) so has to be 0 degrees. You don't have to be too clever to work out that the number in the middle between 0 and 10 is 5 !! LOL Easy.
Now remember this isn't a true 101 on programming curves, just a little something to help you get your head round something you've probably heard a lot about but if you don't program your own Tx - it's something that looks harder that it really is.
Right, This is another curve. Now this one is similar to the one you will find in a Honeybee King CP helicopter in Normal mode. Notice low stick only gives you -2 but high stick still gives you +10. Have a look and see if you can see where the numbers are coming from.
Pitch Curve above would be entered as :
Pt1 = 40 Pt2 = 45 Pt3 = 50 Pt4 = 75 Pt5 = 100
Now this curve would give you a whole 10 degrees of pitch from mid stick to stick high. Loads of response there. Now the range between mid stick and low stick, you're only going to change the blades 2 degrees there, very gentle - just what a new flyer wants (don't want to pull back on the stick only to drive their heli into the ground with -10 degrees pitch !!!) So this is a nice gentle learning curve. Easy isn't it.
Well, I hope you learned a little something, now get back in the air !!!
maz
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