Setting up Raptors (or anything else for that matter) - Mechanical Setup
Simon Lockington

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While on a Raptor these aren't adjustable, on other helis they often are. You want to make sure that at zero degrees pitch (ie half travel), you can draw a straight line between the two ball links. You'll have to adjust the rods to do this.

The aim here is to get the same amount of travel with positive pitch as negative. Here I've got about 7-8 degrees of positive pitch which is obviously not enough. It's likely that I'll have a LOT of negative with this setup, so I'll need to change some more links. At this point, I don't care if I have zero degrees at mid stick.

This is the angle of the pitch arms straight out of the box, see how the right hand side ball is lower than the left hand side one? We want to shorten the long link to lower the left hand side ball and raise the right hand side on, so that eventually you can draw a straight line intersecting the bolt.

This is the end result where I've shortened the long link and lengthened the short one. Unfortunately the angle of this picture makes it look like the right hand link is still lower, it's not, so just be aware of that.

As expected, I've got far more negative pitch than I need, so I'll lengthen the short pitch links to reallocate some of the excess negative pitch to positive.

On Raptors, I just thread the paddle on until I can see the end of the flybar come flush with the opening in the paddle. On other helis I use the vernier gauges to measure this accurately.

With the swashplate level, I line the paddle up with the rotor head (I draw an imaginary line above the top of the blade grips).

This is a two part article in conjunction with Setting up Raptors - Radio Setup. I HAVE ASSUMED YOU ARE STARTING WITH A BLANK RADIO PROGRAM!

I decided to make setting up my Raptor a separate article from the building one because of the demand I figured there would be for it.

At every field that I go to, I’m asked to help someone out with their Raptor, the things are everywhere! For good reason too, they fly so well and are great value for money.

In most cases, I see common mistakes on each Raptor so I thought I’d give a detailed explanation of how I set each one up so you can get the most out of it.

The main concept with setting a machine up is to get the maximum potential out of the machine mechanically, then if necessary, dull the setup down electronically in the radio. At least this way you can be sure that it’s not the machine’s setup that is letting your flying down!

This means that we’ll set the machine up for full 3D flight. Even if you’re not ready for 3D, you should still follow these steps and at the end of the article, we’ll go through how to dull the machine down so it’s suitable for your own tastes.

COLLECTIVE PITCH
You want to make sure that you have equal amounts of ATV. The larger the amount of ATV means you’re using more of the servo’s resolution (in most cases a servo has 1024 available positions, on a 14MZ, that is 2048 positions). If you have a low ATV value then you’re not using as much of the servo resolution as you could, this will mean the helicopter could be jumpy.

I prefer to use larger ATV settings which can give the heli a more settled feeling and allows you to use a much larger percent of the total servo resolution. You may as well use the full capacity of the system you paid for!

FINDING CENTER

• Make sure servo reversing is correct.
• Use sub-trim to find center, find closest spline on servo.
• Make sure both rods are same length and that they are not binding servo.
• Ensure all three balls line up and are equal.

Define total ATV travel with ball off. Put pitch to minimum and push the collective arm all the way down, see how much of a difference there is between the pushrod end and the ball link on the collective tray.

Put the pitch to maximum and push the collective tray all the way up. If the difference between the push rod and the ball link on the collective tray is the same, then your travel limits are fine, you just need to adjust the rod length.

If however there is a difference between the distance between the pushrod end and the ball, then your limits need adjusting. Adjust your ATV (either up or down) and repeat the process until the distance between the collective tray and the ball link is the same.

All we are worrying about at this point is that we are getting the full range of collective travel, don’t worry about the actual pitch values, we’re setting the machine up for it’s full potential which can then be dialed down electronically in the transmitter. My ATV’s on pitch are now 85% which is as low as I would want to go. If I’d had to go lower, then I would have decreased the size of my servo horn to get increased servo movement.

Use Loctite on servos with metal output posts.
Believe me when I tell you to use a dab of Loctite on the servo screws that thread into servo output shafts if they are metal. I didn't and one day as I was getting prepared for the 2005 World Champs I watched helplessly as one of my Sylphides rolled all by itself into some big shrubs because the screw on one of the 9255 servos had unthreaded. I now religiously put Loctite on metal geared servos.

AILERON:
The important thing about this part is making sure the ball link of the aileron arm is in line with the screw that holds the elevator cradle.

From there, you then adjust the length of the rods that go between the bell cranks to the aileron servo horn, ofcourse you would have first made sure your servo horn was all centered up (using sub-trim if necessary).

Once you have all the bell cranks lined up, then you can adjust the vertical rods between the bell cranks and the swashplate until both of these are the same length and line up with the swashplate correctly.

If you’ve done these steps correctly then the swash will be level enough that you won’t be able to see any incline. There might be one there, but it will be very small.

ELEVATOR:
With this servo, you setup the sub-trim after you’ve completed the rod adjustment.

With the elevator you adjust both links between the intermediate elevator bell crank and the servo on equally until they both will fit comfortably on the servo horn ball links. The important thing is that they are both the same length so ensure this is the case.

Once the links are fitted to the servo horn, then use the subtrim to ensure the swashplate is flat.

Don’t be afraid to adjust the linkage between the intermediate bell crank and the elevator cradle lever if you believe that your servo is adjusted correctly but the swashplate is still at an angle.

THROTTLE:
Make sure you have a straight line throttle curve and that your throttle trim is all the way down.

The important part here is to make sure the ball link on the servo horn is positioned the same distance out from the center as the ball link on the throttle arm on the carburetor.

What we are aiming for is that at 50% throttle that the throttle body on the carb will be half open and the linkages are at right angles.

In an ideal world, the ATV of your throttle linkages would be the same, or less than, your pitch ATV’s (assuming you’re using the same servo type for both applications), this is because ideally you don’t want the throttle servo lagging behind the pitch, but in reality, this really only matters when you are doing hard 3D and even then, the effect is minimal.

Because of the different way that the throttle trim works (it only affects the bottom part of the travel, not the top as well like the other functions), you may find that you are using less ATV on the bottom part of your travel than the top. For instance on my Raptor, I’m using top half of 100% and bottom of 90% with the throttle trim all the way down.

The throttle linkage is the easiest one to get the linkage length right. Simply measure the length between the center of the servo output post and the center of the carb throttle body shaft and make your linkage so the centers of each of the push rod ends match up to that measurement.

Once that is done, adjust the ATV’s so that you’re getting maximum throttle, and absolutely minimum (ie engine cut).

GYRO & TAIL SETUP:
This is where a lot of people make mistakes… This section is related to Futaba gyros only as that’s the only ones I use and they are the best gyros on the market at the moment.

This gyro is a GY601, but the same principles apply to the GY502 and the GY401 as well.

First up: YOU DO NOT HAVE TO TRIM THE TAIL IN NON-HEADING HOLD FOR THESE THINGS TO WORK!

That’s a carry over from the old days when you had to first get your tail to hold when the gyro is in rate mode by mechanically trimming the tail linkages.

YOU DON’T DO THAT ANYMORE (for Futaba gyros anyway).

You’d be amazed how many people I come across who have problems with their tail and have tried to set up their tails the old skool way.

Futaba gyros don’t care where center (ie where the tail is holding) is. All they care about is the limits that they can move their servo between so they can do their job.

What IS important is that the limits in each direction are the same.

But Si, you aren’t making any sense! We need to set the trim in rate mode!

The reason why you don’t set the trim in rate mode is because the tail trim will be different depending on a LOT of different combinations such as hovering head speed and hovering pitch to name the two main components. You might get the tail spot on mechanically with one combination, but as soon as you go into Idle Up where the headspeed increases, the trim will change. If the engine goes lean or rich, it will change, so what’s the point? The gyro really doesn’t care.

Why is it important to have equal travel on both sides, and why should those values be large???

The gyro wants to know how far it can move the servo to the left and right to make the appropriate compensations. It’s important that these values be equal so the gyro gets a linear progression when it tells the servo to move.

Remember earlier in this article I talked about servo resolution and why you should have your ATV’s set to a relatively high value (ie about 100%)? Well the same goes for the tail servos, the gyro is a finely tuned instrument capable of making minute adjustments to keep the tail steady. If you have cut down the amount of servo resolution by having a low limit value (ie 80% for gyros), then you’re making life harder for the gyro than if you had that value at 120% which gives the tail servo more ‘room to move’.

Another bit of evidence that Futaba gyros want equal limits on both sides is with the GY401. Both the GY601/611 and the 502 have independent limits for both sides, you can set the values to what you want, but the 401 doesn’t. It only has a total limit value, not independent values, it REQUIRES that both sides of travel are equal. You’re required to adjust your mechanical linkages so that the 401 can use the total amount of travel. You should do the same for your 502, 601/611.

Make sure that your tail servo is operating in the correct direction, and also, that your gyro is working in the correct direction.

How do I check my gyro’s direction?

My way is pretty basic, once I’ve established that the tail servo is going in the right direction, I look at which way the servo horn when I move the rudder to the right. Then I grab the boom and swing the nose of the helicopter to the left and make sure that the servo horn moves the same way as it did when I moved the rudder stick to the right. If it didn’t, then you need to alter the gyro’s direction.

Ideally, you want to set your gain to about 37% or so.

On the GY601/611 on my 3D models I have the mode set to 3D. I found that the gyro seemed to perform a little better during pirouetting maneuvers in 3D mode, but it really doesn’t matter much.

How do I know what servo horn to use on the tail?

Ideally you want the tail servo travel to be about 120-130% so adjust your servo horn’s length until you can obtain that.

ROTORHEAD
In the previous steps of setting up the servos, all the linkages up to the swashplate were setup, now we have to setup the linkages from the swashplate up.

There are really only two sets of linkages to work with here, the ones going from the swashplate to the pitch arms (mounted on the flybar seesaw), and the linkages going from the pitch arms to the blade grips.

First of all I start with the ones going from the swashplate to the pitch arms. I adjust these until all three ‘holes’ on the pitch arm line up horizontally, ie the center of the ball links on each end of the pitch arm scribe a straight line through the center of the bolt holding the pitch arm to the see saw.

Once I have that complete, then I put a blade on and set the top and bottom pitch but adjusting the shorter rod between the pitch arm and the blade grip only. I do this until both top and bottom pitch is equal. I don’t worry if center stick is zero degrees.

Once this side of the rotorhead is setup, I’ll mark that blade grip and blade so I know which one is the master blade. I then measure the length of each ball link and replicate these links on the other side. Once this is done, the blades should be in track, and if they’re not, they’ll only be a turn or two on the long link out.

PADDLES
With the helicopter on, I install the paddles using grips to hold the flybar (to not burn out the servos). I’m using the white paddles (intermediate weight) cause I had them lying around.

I thread the paddles on until I can see the end of the flybar come flush with the hole in the middle of the paddle.

With the helicopter on, I adjust the angle of the paddle so that a horizontal line drawn through the paddle lines up with the top of the blade grips. I then do the same with the other paddle.

WEIGHT DISTRIBUTION
Normally I don't worry about this too much on my 3D machines, but generally you would want the helicopter to balance level (or slightly nose heavy) with half a tank of fuel, you don't want it to be tail heavy. I generally just adjust the location of things like the battery, radio etc to get the balance as best I can.

Now you've setup your machine mechanically, you should continue on and setup your radio! Setting up Raptors - Radio Setup