Gotta_Fly

My Feedback: (2)

Hello
I bought a HFP-10 servo programmer awhile back, and I don't mean so sound stupid but I'm having terrible time figuring out how to match two servos up, another words I'm trying to set up my left wing on my H9 33% and I already installed both 5645 Hitec digitals servos, but now I don't no where to start, I must be having some type of mental block, if there is anyone who can help me through this I would very much appreciate it..

Thanks

Braxton

hilleyja

My Feedback: (3)

Welcome to Club Frustration.

I'm in the same boat as you and frankly the fact that Futaba's TX pulse width for neutral is different than what the programmer expects makes it even more frustrating.

Since I've been playing with mine for over a year and have picked up a few pointers I will try to help -- do not take this as the definitive answer to your question because I do not claim to be an expert.

This is the approach I would take for your needs:

*** WARNING: DO THIS STEP WITH THE SERVO OFF THE AIRPLANE OR AT LEAST WITH THE SERVO ARM REMOVED ***
First, reset each servo to the factory default (recommend before each attempt to program a Hitec digital servo). Connect the servo to the programmer and enter into the 'Program Reset' function. Then push both the "UP/L" and "DN/R" buttons at the same time. The servo will cycle to max deflection in both directions and stop. I then enter into the S-Test Manual function and set the servo to 1522 (My TX is a Futaba 9C)

*** RECOMMEND YOU DO THIS ON THE AIRPLANE ***
Second, with each servo connected to the control surface, one at a time, find the center of the servo and set its maximum clockwise and counterclockwise direction. Center the servo by entering into the EPAneuFS (EPA, Neutral and Failsafe) function. Turn the programmer knob until the servo control arm is exactly perpendicular to the servo case; push and hold the 'M' button on the programmer. Mount your Throw-meter to the surface. Turn the programmer knob counterclockwise until your control surface has been moved to its maximum deflection; push and hold the 'UP/L' button. Turn the programmer knob clockwise until your control surface has been moved to its maximum deflection; push and hold the 'DN/R' button. Turn the programmer knob counterclockwise until your control surface is back to neutral. Disconnect this servo from the control surface and connect the other servo -- REPEAT.

It is just that simple. Since Futaba, JR, Airtronics, and Hitec do not agree with each other as to the pulse width of neutral you will have to make a subtrim adjustment in the TX with both servos connected to the control surface.

NOTE: Recently I read a post here on RC Universe that might provide a solution to the pulse width differences between TXs. When initially setting up your TX for your airplane, connect the programmer to each RX channel and, in-turn, adjust the channel's subtrim until the TX pulsewidth is exactly 1500. I haven't tried this yet but it seems promissing.

mglavin

My Feedback: (31)

Something to consider is not all TX's offer the same neutral pulse, 1500us is desired, BUT seldomly realized. It has to do with the acceptable OEM component tolerances and the physical setup of the specific TX in play. It is not a gimme with any two TX's... There all different.

Be sure all your trims and sub-trims are neutral and use the programmer to ascertain what the actual neutral pulse width is of your TX.

I would simply use trial and error from here to program the neutral point. It will take a few attempts to get close and then you can narrow it down from there, take notes on the settings so you can extrapolate the needs for the next attempt.

MR G

hilleyja,

I am also having some frustration in matching two servos mounted to one aileron control surface (I need to do this twice, once for each wing half).

I understand and agree with your steps, the question I have is this:

You said: "It is just that simple. Since Futaba, JR, Airtronics, and Hitec do not agree with each other as to the pulse width of neutral you will have to make a subtrim adjustment in the TX with both servos connected to the control surface."

I am using a single channel to drive both servos on the control surface. adjustments to the subtrim will affect both servos on that channel. How can the use of subtrims perform the final adjustments to match the servos.

Also I have tried using the subtrims to adjust the transmitter to output a nuetral at 1500us, but by doing this you will throw out the endpoint settings.

My setup is as follows:

Futaba 9C transmitter.
Servos are HITEC 5945's
aileron channels are 1 and 7
channel 1 will be Y'd to both servos on one wing while channel 7 will be y'd to both servos on the other wing.

My ailerons are top-hinged so I will have to use Ail-Diff to make my rolls axial
Airplane is Comp-Arf 2.6 Extra 330 with DA-100

Any more help or insight would be greatly appreciated.

I have alot of people who are hounding me to fly this bird, and I really want to, but I will not until I'm comfortable with the servo setup(Servos not fighting each other).

Thanks in advance,

MR G

mglavin

My Feedback: (31)

Sub-trim can be utilized of the specific channel to dial in it's transmitted pulse width to the desired 1500us at neutral. Lets say your aileron channel outputs 1510us at neutral with trims zeroed out. Dial up the sub-trim and offset in the correct direction the required percentage to realize 1500us at neutral. You'll have to use the programmers pulse width measurement mode to know what is actually being transmitted in pulse width. Simply programming the servos for 1500us at neutral brings us to a conundrum of sorts, yes we want the servo to rest at 90 degrees to the surface to realize linear actuation, but the darn TX's in use seldom transmit neutral at 1500us, therefore were in search of a fix. Matching the servo to the TX is best, while using sub-trim works with some caveats.

I would suggest you program the servos to realize the TX's neutral pulse width verses utilizing sub-trim. This is the beauty of the programmable servo, full linear travel can be realized at any center/neutral desired with the desired throw as well. Nothing else offers or realizes this degree of precession, nothing...

Gotta_Fly

My Feedback: (2)

Hello Michael
I was wondering for those few of use who dont have this HFP-10 down to a science, is there a site or a place you could recommend that teaches us step my step instuctions..
Thanks


Braxton

mglavin

My Feedback: (31)

Brax

There is nothing that I am aware of. If you have additional needs just ask... I statrted to write a tutorial and will finish it one day. There is just so much time in every day and I have projects backed up NOW...

hilleyja

My Feedback: (3)

It shouldn't because setting the subtrim to 1500us would be the 1st thing you do before programming the servo. The programmer uses 1500us as the default neutral; when you find/set the center point in the servo with the programmer you are programming the servo to be at that position when it receives a 1500us pulse. Setting the subtrim on each channel of your TX so that it reads 1500us guarantees that a neutral signal coming from the TX is 1500us -- it should center your programmed servo.

In any case, mglavin proposes, what I feel is, a much better solution. His approach is much more accurate than just setting the subtrim to 1500us and maintains linearity in the adjustment because you end up using a subtrim of '0' in your TX as neutral. I plan on reprogramming my Aeroworks X300L according to his procedure. Check out his post on another thread and my response to it:

http://www.rcuniverse.com/forum/m_18...tm.htm#1849750