How to Install a Futaba GV-1 R/C Helicopter Governor

How to Install a Futaba GV-1 R/C Helicopter Governor

So I decided to add a toy to my helicopter- a Futaba GV-1 engine governor. I browsed the manual in the store just to make sure I really wanted to do this. I missed the part about drilling holes in the engine cooling fan...but all was not lost.

So here's what needed to be done:

Pull the engine out, remove the fan, drill a -*get this*- 4.1mm hole in the fan. Not all the way through, but just enough to put a 4.1mm magnet in there. Attach the sensor to the engine with the included hardware (worked well!) and then set up the control unit.

Just as an aside- why in the hell did they have to make the magnet 4.1mm? No one makes a drill bit that is 4.1mm, 3mm and 4mm yes, but not an odd size like 4.1mm. Thanks Futaba. Of course after the fact 4.1 probably converts to some even number in inches....

First thing to do according to the directions is to put the magnet on the fan by way of measuring. I decided to put the sensor on first and then figure out the magnet. This is what the sensor looks like when mounted at the right distance from the fan on a OS 32 ringed engine:

To get the right magnet spot, I put the magnet on the sensor and screwed the fan down on it. Holding it with a really small allen key so it didn't run off the sensor. This is what it looks like when the fan is screwed down:

Now, how do you get the position for the magnet? Get a mechanical pencil with REALLY soft lead in it. Draw lines around or across the magnet's position on all 4 sides. This picture is of the mark left by the pencil. I suppose you could use a marker, but it needs to be REALLY thin to get in there right (it's really a light mark, but the blow up should show it better (I inversed the insert image to show it a bit better):

So I got the hole in there. In the process of making it just the right size for a tight fit I ended up drilling clean through the fan. Not to worry, 30 minute epoxy to the rescue. The instructions say only to drill deep enough for the magnet to sit in there with some epoxy. I ended up putting the magnet in there and filling the reverse side with epoxy like this:

The manual recommends 30 minute epoxy. I used this and waited about an hour for it to cure (directions say 8 hours).

Before flight and before putting the engine back in the manual says to check to see what the sensor signal is. Should be 60% or better. I got 97% which looks like the max you can get even by putting the magnet on the sensor. To check then plug a battery into the gov box along with the sensor and rotate the magnet over to the sensor. There is a menu option for testing the sensor, should look like this (there is supposed to be a % next to the 97, but it flashes and I missed it):

With this method I can't imagine getting the magnet so far away that you'd get anything less than 97% but who knows.

Some setup is required before flying. You need to set your gear ratio. For the Nexus 30 it's 9.8. This gets entered into the control amp. There are a lot of other options that may or may not apply to you. The major ones are how to turn the gov on/off, setting the idle, high and off servo points and battery failsafe.

I turned off the battery failsafe. If my battery fails, my helicopter is lost. No point in returning the throttle to idle...

The on/off stuff is REALLY important. Some folks have an extra radio channel that can be used for this. Since I have a heading lock gyro, my accessory channel is used for turning it on and off. So I have to use the stick position. The gov turns on when your throttle gets to 15% of max. This is set via the high, idle and off servo settings. Don't foget to do this first!!!

Once this was setup there is a mode the control amp can go into to show you where it will turn on. This can be done with the radio on and the engine off.

So, confident that the basic setup was complete I went to the back yard.

So after an hour of clean up and reassymbly (didn't take that long but I went over the whole heli just in case....) I went out to the back yard to crank it up and see if there were any balance problems introduced. Futaba included an extra magnet incase balance was a problem.

I fired it up without the Gov between the throttle and my radio. My first task was to get an rpm reading from it to see if it even worked. The control amp will give you either a rotor rpm or engine rpm. Sadly the max rpm function ONLY works if the throttle goes past 95%. Since it wasn't hooked up to the receiver yet I couldn't get this data.

My idle rotor rpm is around 540 according to the gov. But at this speed, my clutch is barely engaged so this didn't mean much. Once I was happy that I was getting a reading, I set the gov for 1000 rotor rpm, plugged it all back in and went for a spin.

Why so low? Well my throttle curve is linear from 0 to 100. The best way to see if the gov is working is to tell the radio to do something different from what the gov should be doing. So, infact, the rotor rpm stayed way down even through the throttle curve should have had the rotor going much faster. Success!!

Now that I knew it work, I set the rotor rpm for 1350 and flew for about 20 minutes. Worked out really well. Very consistent.

At the flying field the next day my only problem was that when trying to loose altitude, the gov would kick off and things would slow down again- which basically means that my blade pitches are not set properly- should be near zero pitch when at about 15% stick which isn't the case.

So I need to fix that but otherwise my goal was met which was to prevent the rotor from going too fast when the wind decides to provide some lift. My area of Florida is windy most of the time and I've had a few problems with the rotors going way to fast on descent because of up drafts and such. This keeps the rpm more consistent and the forward flights are much better.

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