Power systems/ Hitec A9?

[Xpress]

Hitec recommends against running two receivers. The receiver can handle up to 30 volts. Some guys run a y harness to a servo. One end goes to the servo, the other half of the y goes to a reciever battery. Every channel could have its own battery technically. The hitec receivers are basically a power expander themselves.

I heard that on the a9 to. Wonder if they still say dont run two rx with the a9x?

You can run 2 receivers with the 9 or 9X if you want, they just can't be Optima receivers as the telemetry information coming from 2 receivers will cause interference. I don't recommend Minima receivers on big airplanes though.

The Optima receivers can handle up to 35 volts through the SPC port only, otherwise max voltage through the servo ports is 9 volts. The SPC port only powers the receiver, you will need to provide separate power to the servos if you utilize the SPC port. We use the SPC port to tell us what our flight battery voltage is (utilizing a jumper tied into the ESC's battery leads) and we set an alarm to notify us when the flight pack voltage drops below a threshold. No more setting a timer, it's based off of the actual voltage.

As far as y harnesses, I am not sure if they are saying run a y harness to right and left ailerons like a parkflyer. That I don't think would work very well. The servos would definitely fight each other.

You would run a y-harness to the left wing panel to tie the left aileron servos together into 1 channel, and run a y-harness to the right wing panel to tie the right aileron servos together into 1 channel. The servos will fight each other if you don't re-program them, which is what we always recommend doing. RC car guys do this all the time with twin steering servo setups as they only have 1 channel for steering (yes they burn them up but because they don't program the servos so the center and end points match). There is no issues with doing this, and this is how several of our team pilots have their giant scale (up to 40% even) airplanes setup.

 

[witchfingers]

You can run 2 receivers with the 9 or 9X if you want, they just can't be Optima receivers as the telemetry information coming from 2 receivers will cause interference. I don't recommend Minima receivers on big airplanes though.

The Optima receivers can handle up to 35 volts through the SPC port only, otherwise max voltage through the servo ports is 9 volts. The SPC port only powers the receiver, you will need to provide separate power to the servos if you utilize the SPC port. We use the SPC port to tell us what our flight battery voltage is (utilizing a jumper tied into the ESC's battery leads) and we set an alarm to notify us when the flight pack voltage drops below a threshold. No more setting a timer, it's based off of the actual voltage.



You would run a y-harness to the left wing panel to tie the left aileron servos together into 1 channel, and run a y-harness to the right wing panel to tie the right aileron servos together into 1 channel. The servos will fight each other if you don't re-program them, which is what we always recommend doing. RC car guys do this all the time with twin steering servo setups as they only have 1 channel for steering (yes they burn them up but because they don't program the servos so the center and end points match). There is no issues with doing this, and this is how several of our team pilots have their giant scale (up to 40% even) airplanes setup.

The spc port is basically useless for gas planes in my opinion. I usually run one receiver pack into the battery port and one in a spare channel. As far as y harnesses go, i would like to just use a power distribution device. I will just program my servos individually. With a y harness I would worry about the one servo plug being over amped by those 2 servos going into it. There is no need for me to skimp at this point. Gotta pay to play. With 100cc size and up planes becoming more popular, Hitec is going to have to introduce larger radios.

 

[emtp275]

The spc port is basically useless for gas planes in my opinion. I usually run one receiver pack into the battery port and one in a spare channel. As far as y harnesses go, i would like to just use a power distribution device. I will just program my servos individually. With a y harness I would worry about the one servo plug being over amped by those 2 servos going into it. There is no need for me to skimp at this point. Gotta pay to play. With 100cc size and up planes becoming more popular, Hitec is going to have to introduce larger radios.

This is exactly how my 104 is set up on an expander pro, Only issue I have is I bought it used and the guy who set it up programed the wings and they work great but he put the rudder servos on separate ch for some reason and now I need to buy a programer to free up one of those ch so i can run smoke, other than that the plane has been amazing, I will say 9 7955 are hungry and will kill two 2600mah batterys in 4 flights lol

 

[Xpress]

The spc port is basically useless for gas planes in my opinion.

It wasn't designed for that in mind, it was mainly for electrics.

With a y harness I would worry about the one servo plug being over amped by those 2 servos going into it.

We don't worry about it, we've got guys hucking the absolute skiznibs out of their GS airplanes without issue. Using the proper connectors is important here, but to each his own.

Maybe time to go with our HSB servos, which draw ~2/3 less than a traditional digital

Hitec is going to have to introduce larger radios.

 

[witchfingers]

It wasn't designed for that in mind, it was mainly for electrics.



We don't worry about it, we've got guys hucking the absolute skiznibs out of their GS airplanes without issue. Using the proper connectors is important here, but to each his own.

Maybe time to go with our HSB servos, which draw ~2/3 less than a traditional digital

I will have to read up on those new servos. For now I am running 7954sh on elevators and ailerons and 8380 TH on rudder.

 

[Xpress]

I will have to read up on those new servos. For now I am running 7954sh on elevators and ailerons and 8380 TH on rudder.

They're brushless servos. We designed them with a NEU brushless motor inside that's way super powerful, so powerful that if we removed the governor they could make upwards of 800oz of torque! We limited the power output of them so that the case and gears wouldn't break, which also in turn makes the entire servo more efficient. And unlike a conventional servo that draws more and more amperage when it stalls, these guys only draw their max current then the motor is actually spinning- when they stall, the current drops significantly. You could stall these servos all day long and they won't kill themselves.

Infact, it's extremely difficult to stall these servos as they have so much more holding force compared to a conventional digital. Unlike a regular digital that makes its max torque around the center point, these servos make their max torque throughout their entire travel range- there aren't any peaks and valleys, it's all smooth and linear. Plus with how efficiently we designed these servos, we made it so that they make their max torque at both 6, and 7.4v. You can operate them off of a 5 cell nickel pack all the way up to a fully charged 2s lipo pack and they still make the same torque, the only variable that changes is speed! They are worth every penny you spend on them.

We have an assortment of them however for GS airplanes I'd recommend either the 9370 on ailerons or the 9380 on tailfeathers. Both of which have the aluminum heatsinks to keep the servos icy cool. We had a few people report that the hottest they got was just a little warm, as compared to regular coreless digitals in the same torque/speed class get notably warm to the touch.

 

[Terryscustom]

..........

 

[witchfingers]

The 8380 I have drops right in the servo cut out. I am not sure about the 9 series servos xpress mentioned. This 8380 requires futaba 25 spline arms. Had to go back to the hobby shop to swap the arm out.

 

[Terryscustom]

The 8380 I have drops right in the servo cut out. I am not sure about the 9 series servos xpress mentioned. This 8380 requires futaba 25 spline arms. Had to go back to the hobby shop to swap it out.

That's cool, I had three of the 7980's and they were a huge chore to mount in stabs.

 

[Xpress]

I believe the 7980's are just a hair larger because it's a beefier servo. Needs just a little bit of extra room inside.

The 8380 I have drops right in the servo cut out. I am not sure about the 9 series servos xpress mentioned. This 8380 requires futaba 25 spline arms. Had to go back to the hobby shop to swap the arm out.

For future notes for all:

Hitec HS5XXX and HS7XXX servos: 24 spline
Hitec HS8XXX and HS9XXX servos: 25 spline