I have a few questions about the helicopter radio that I will ask in this thread. My radio is the Futaba 9CHP Super and I only started to explore its functions recently.

I have a question regarding the throttle curve and the pitch curve. I understand that the curves shows the relationship between the stick position and the "throttle" and "pitch" respectively. But all I see is a curve, no numbers or values. It's easy to see the stick position on the curve and that's the X-axis, and there is also a vertical line that moves along the X-axis that correspond with the stick when you move it. That way, I know the left end of the X-axis (origin) correspond to the low stick end, and the rightest end of the X-axis correspond with the upper end of the stick position.

But what about the Y-axis? There are no values or anything. If I was looking at a pitch curve, how do I know the pitch value (in DEGREES). The position on the pitch curve is meaningless unless I know what the end point values are. I need to know the pitch that the bottom Y-axis (origin) correspond to, and the pitch the upper Y-axis correspond to (in degrees). I also need to assume the relationship is linear. So if the bottom of the curve correspond to -3 degree, and the upper most of the curve correspond to +10 degree, then I'll assume the mid point is +3.5 degree, IF it's linear, which I'm not sure. Is it?

And how do I know the values that the bottom and top of the Y-axis correspond to? In my example I used -3 and +10, but on the radio there are no numbers. Where do I find this information? Does it have anything to do with servo endpoints?

A little confused.

Thanks.

First, normal is enabled by default but any other pitch curve you have to goto the corresponding throttle curve menu to enable it.

Then you cursor down to the numbers and adjust them with the jog wheel.

Best practice is to do a 3d setup on your helicopter with plus and minus 9, 10, or 11 degrees, set by using a pitch gauge and depending on your engine Lets say +-10, ideally then you would have -10 degrees = 0 percent -5 at 25 percent, 0 at 50, 5 at 75 and 10 at 100

In reality its best to have +- 11 or 12 by end points, and setting the rest of the points by the pitch curve numbers, then use all you can get up top for your throttle hold curve.

Check out http://www.raptortechnique.com he's got programming for the Raptor and the 9C, unless you have a CCPM heli they work the same way for the most part.

You will not find anything in your TX that will give you the degrees in which your blades are at ...

The only thing the curves ( or y-axis ) tells you is the servo command that will be transmitted when the stick is in that position. Since you can install a servo arm in numerous positions and have variable length control links ... it is up to you to set up the heli to make the TX numbers make sense ... ie set the Y-axis at 50%, set the heli/servo up to be centered, etc.

Bottom line is, your TX has no idea what it's transmitting to or what it's doing. It is up to you to make the heli and TX work together.

For example, you could set the low stick (pos 1) Y-axis to cause the low pitch to be -3° in normal mode by dialling in the numbers to achieve the desired pitch ... read from the pitch gage you are using. Then in idle up, you could set pos-1 to achieve -8° pitch just by changing the numbers.

"The position on the pitch curve is meaningless unless I know what the end point values are."
Again, if you are trying to make some meaningful connection between your TX settings to get a meaningful pitch angle, don't bother. It won't happen. The only meaningful thing you can read is the pitch gage attached to your main rotor.

"Where do I find this information? Does it have anything to do with servo endpoints?"
100% on the curves equal 100% of the ATV settings. ATV settings are the limits of the servo movement. Typically, most people shoot for 100% ATVs. So if you dial in 50% ATVs then 100% curve settings would be 100% of the ATV setting.

Where do you find the degrees in which your rotor blades are at? On the pitch gage attached to the rotor blade. You do have a pitch gage don't you? Again there is no magic TX menu that will tell you that your rotor blades are at hover pitch. The TX will only tell you what the command to that channel/servo is. It's up to you to make it meaningful at the heli end.

Ok, so let me get this straight. I just want to learn my radio so I know how to set up a helicopter myself.

First, I set the servo arm 90 degree to the linkage at mid stick. I setup the servos so they give me max throw in either direction without binding using the servo's endpoint on the radio.

If I run with 0 degree pitch at mid stick, the swashplate should be level and all the arms and linkage should be parallel and/or perpendicular. This is the mechanical setup.

At this point, assume I get -10 and +10 if the throttle curve is a straight line from point 1 all the way to 5. This means if I move the stick to the extremes, and I measure the pitch with a pitch gauge, I get -10, and +10.

But if I only want to have a minimum pitch of -3, I can just adjust the point 1 (or 2 if needed) on the radio so that the curve never come close to the origin (bottom of y axis, which is -10).

Then if I want more negative pitch on idle up, all I have to do is change the curve from the radio without even touching the mechanical setup.

Is that right?

For best response make the servo move as much as possible by using the correct hole in the servo arm, then fine tune with the end point settings.
Pitch curve, not throttle...
Yup, right again. As you've realised, the 'Y' axis on those curves represents end to end servo movement as defined by the end point settings. Bare in mind that the only points defined for the servo are the actual end points so if you change one you will also change the actual possition of the servo arm for all other possitions, ie, the mid point is always halfway between the two end points, so moving an endpoint will move the mid point.

For this reason, do the mechanical setup first trying to get it as accurate and symetrical as you can. Only use the endpoint settings to fine tune out any binding you can't remove by mechanical adjustment. Then adjust your pitch curves to give the precise blade pitch required for stick possition.

You're getting there. That's the beauty of the pitch and power curves, you the heli pilot can set them any where you desire. This is also how the "v" curve developed for the power curve.

For example (numbers are just examples), in idle up, if you want to fly inverted, you just build a pitch curve from ex: -10 to +10 with 0 at mid stick. Out at the ends (-10 & +10), your power curve points (pos-1 and pos-5) are going to ge high (ex: 90%) but at mid-stick (pos-3) you you have to set this to something low (ex: 25%) because you don't need all that power pushing on 0° or you'll over rev the engine/rotor.
So, in this example, pos-1 will be high (ex: 90%), pos-3 will be low/mid (ex:25%) then pos-5 will be high again (ex:90%). This draws a "v" on your curve.

So to fly inverted, just use pos-1 thru -3 and to fly right side up, use pos-3 thru -5.

The ability to design curves is what cause the extinction of the Invert switch and functions.

Just remember that you must get the power and pitch curve "in sync" so that you produce just the power needed at a particular pitch in order to keep the RPMs constant.

It's a balancing act really

Ok, I understand it better now.

What about ATV? Is that just the servo end point? I see people talk about 100% ATV or 140% ATV and I'm still a little confused. Especially the 140% ATV. What is the significance/meaning of something greater than 100%? Why can't they just make the max 100%?

Also, when I first set up the servos mechanically, I have to make sure to center the servo with respect to the servo arm right? You know there are a lot of ways you can put the servo arm(star) on the servo output shaft... I have to make sure I put the servo star on the output shaft in a way so that the servo arm used (the one with the linkage attached 90 degrees) is in the "middle" position of the servo movement range, so that the servo can move in either direction equally. Right?

Where do all the programming get stored? The receiver? The servo itself doesn't have any memory right? So this means if I get a new receiver I got to reprogram everything. I'm just guessing. Please inform me.

Thanks

All settings are stored as a model memory in the TX.
Based on this programming/switch position/stick postion, the TX computes an appropriate command for each channel and mashes it all together and transmits a representative signal into the atmosphere on a specific carrier frequency.

ANY RX, tuned appropriately to that frequency will pick up the signal and attempt to decode it. If all is compatible, the RX will translate the signal into independant channel commands and send it to "whatever" is connected to that channel socket whether it be servos or gyros or other things. The device (servos,gyros,etc) must be capable of doing something with this "servo" signal. Unfortunately, the servos are dumb, they will respond to anything sent to them from the RX ... whether it's right or wrong (ie you select the wrong model in the TX, RF interfence, someone with a TX on the same frequency, etc).

So, the servo will always move to where it is commanded to move because you already have the TX turned on before the heli is turned on. And when the heli/RX/servos/gyro is powered on ... they will be sent a command that the TX has already figured out. So if you swap to a newer improved RX, as long as it's compatible with your TX and it's transmitting mode (ie PPM or PCM) them you will be OK.

That's why the hobby is called RADIO CONTROL.

http://www.torreypinesgulls.org/Radios.htm

ATV = Adjustable Travel Volume, EPA= End Point Adjustment. Two ways of saying the same thing, how far each side of neutral the servo will move with full stick deflection.

Proper mechanical setup will have your linkages and servo arms set up so that you are close to 100 and equal on both sides in most cases. For example lets say that your throttle linkage is binding at 100/100 atv. You lower the atvs till it doesnt bind and find out that you are 60/60, that says you are too far out on the throttle arm, too far in on the servo arm or a combonation of both but your linkage is the right length and everything is centered.

If you end up 110/80 then you have to work on your linkage so that they are both 95 or close to it, do this by adjusting the throttle arm position, the servo arm position and or the length of the rod. The quick way to setup proper linkage length is to measure from the center of the servo screw to the center of the pivot (say the middle of the throttle arm in this example) with calipers and make sure that your linkage from center to center is the same length, the distance from the center of the servo screw to the ball is the same as the center of the throttle linkage to the ball and that both arms are 90 degrees to the linkage at 50 percent throttle and there is full throw with no binding at either end.

thanks for the help.

I like those websites that were posted.