Heli-Max HMXM1500 User Manual

BASIC INFORMATION

One of the most important factors in determining the way a
helicopter handles is the rotor head speed. Once you find a
rotor head speed you like, it is desirable to maintain that rotor
head speed at all times, during all maneuvers. However, there
are many outside factors affecting rotor

head speed such as

flight speed,

acceleration/deceleration, control inputs (rotor head
loading), wind, etc. The rotor head is constantly acted upon by
these and other forces which affect rotor head speed. Over­revving and overloading of the rotor head during maneuvers
results in decreased performance. During the time that the rotor
head has unloaded and rotor speed has increased, the
machine will become jumpy or too responsive. During the time
that the rotor head is overloaded and rotor head speed has
decreased, the machine will become sluggish and less
responsive. This never ending transition causes the pilot to wait
for the helicopter before giving the next control input. This
problem can be minimized with pitch and throttle curves, but it
is not possible to totally eliminate it—until now. The Rotor Head
Speed Governor operates the throttle servo to maintain a
constant rotor head speed at all times. This decreases the
amount of collective stick movements you must make, allowing
you to concentrate more on the other controls!

It is possible to select two rotor head speeds with the Governor.
Typically, a lower RPM is selected for hovering while a higher
RPM is selected for aerobatics. This can be done in flight by
adjusting a dial or flipping the rpm select switch on your
transmitter.

OPERATION

The governor is connected between the throttle servo and the
receiver (the same way a gyro is connected between the rudder
servo and the receiver). Three magnets are mounted to the
main gear in your helicopter. When spinning (at the same rpm
as the rotor head), the magnets pass by a sensor connected to
the CSU (constant speed unit—the little black box). The sensor
reads the rpm of the main gear and sends a signal through the
CSU to the throttle servo, which modulates the throttle servo as
required. The governor will operate between 900 rpm to 2,200
rpm. The pilot determines rotor speed by settings he programs
into the transmitter.

Please note that your governor will not:

❏ 1. Hold rotor head speed when your engine is not

correctly set

up (needle valve settings, exhaust system, etc.).

❏

2. Reach the full 2,200 rpm if your engine does not have

enough power.

DECIDE HOW YOU WILL TURN ON AND ADJUST

THE GOVERNOR

Now you know what the Rotor Speed Governor can do, but how
are you going to turn it on and adjust your rotor head rpm while
you are flying? Following are three methods we suggest for
using your governor.

Method A

Use a two position switch to switch between a lower rotor head
speed (for hovering) and a higher rotor head speed (for
aerobatics). This means that in addition to flipping the switch for
your different pitch curves (Normal, Idle up 1, Idle up 2), you
will also have to flip the rotor head speed switch to access your
other rotor head rpm. For example, when you go from your
normal pitch curve for hovering to your idle up 1 pitch curve for
aerobatics, in addition to flipping your idle up 1 switch, you will
also have to flip the governor switch to activate your higher
rotor head speed. The way you adjust the RPM for each switch
position (your two rpm ranges) is to change the ATV’s for both
ends of the switch. This means you can vary the rpm only on
either side of your “middle” rpm which will be around 1,400 rpm
(1478 rpm to be exact). In other words, the two rpm you can set
are only above 1,400 rpm (when your switch is in one position)
and below 1,400 rpm (when your switch is in the other
position). You cannot have rotor head speeds of say, 1,600 rpm
and 2,000 rpm because they are both on the same side of the
ATV range.

Method B

Use an adjustable dial or slider to change your rotor head
speed. This allows infinite adjustment of your rotor head speed
(between 900 and 2,200 rpm) in any of your pitch curves, at
any time. But, you will have to manually adjust the dial while
you are flying. This might be a good method for starting out
while you get the feel for how your governor operates. With this
method, you can also turn the governor off at any time (instead
of when your throttle stick drops below a preset point when you
land, as in method A). For example, once you have established
a hover and set your hover rpm with the dial, use the dial to
increase your head speed when you go into your aerobatic
pitch curve. Similarly, when you switch back into your hover
pitch curve, adjust the dial to lower your head speed.

Method C

Use your pitch curve switch (Normal, Idle up 1, Idle up 2) to
access your pitch curves and simultaneously activate
corresponding rotor head rpm preset by the governor. This
requires a computer radio with programmable mixing where
you can alter the center point of the channel that determines
your rotor head rpm (to preset the rpm for each of your
conditions—Normal, Idle up 1, Idle up 2). Use the “offset”
mixing type instead of linear mixing type.

Rotor Head Speed Governor

INSTRUCTIONS

Congratulations and thank you for purchasing the Heli-Max
Rotor Head Speed Governor. The Governor is ideal for
expert aerobatic pilots who demand a constant rotor head
speed in order to maximize their helicopter’s performance,
and for novice pilots who wish to simplify pre-flight setup
(actually, experts can realize the benefits of simplified setup
too!) In other words, the Rotor Head Speed Governor is for
everybody!

Before you test and install your governor, if possible, you
should test fly and set up your helicopter to perform the way
you like.

HOOKUP THE GOVERNOR

Your governor comes equipped with Futaba®brand “J” style
connectors. If you own a Futaba radio system, proceed to step
1 below. If you own another brand of radio, you may have to
modify the connectors on your governor. See the diagram
below for proper polarities for major radio brand connectors.
Usually, all that is required is to carefully remove the key on the
connectors on the governor with a utility knife so they will fit into
the slot on your receiver. If you’ve modified your connectors,

make certain the wiring order on your governor connectors
and the servo connectors is the same as the wiring order on

the Futaba connector.

Study the diagram carefully. The positive (+) wire is the center,
the negative (-) wire is on the side opposite of the key on the
connector and signal (S) is on the side of the connector nearest
the key. WARNING! Failure to match polarities on any

connector

may damage your gyro and will void your warranty.

❏

1. Connect your throttle servo to the bottom output of the

governor.

❏

2. Determine whether you will use a dial to vary your rotor
rpm or a two position switch to switch between a preset high
and low rpm. Connect the lead with a band from the governor

to the channel on your receiver that is operated by the switch or
dial you selected to control rotor rpm (usually Auxiliary 1).
Some pilots with advanced computer radios may choose to use
their programmable mixing and flight conditions to mix preset
rotor rpm with their pitch curves (Idle up 1, Idle up 2). When
different pitch curves are switched on (Idle up 1, Idle up 2), the
preset rotor rpm will be selected without having to adjust an
additional dial or switch.

❏

3. Connect the lead from the governor without the band to

the throttle servo output on your receiver.

❏

4. Connect the governor’s sensor lead to the top output of

the governor.

SET UP AND TEST PROGRAM

Determine The Active Side Of The Magnets

❏

1. Place the test jumper in the test mode on the governor

(refer to the previous diagram).

❏

2. Turn on your transmitter, then your receiver.

❏

3. Place one of the magnets on your workbench. Pass the
sensor over the magnet within a distance of 2mm or less. Note
that the printed side of the sensor, not the end, reads the magnet.

❏ A. If the LED on the governor glows, use a felt tip pen to

mark

the upward facing side of the magnet as “active” (mark an “A”).

❏

B. If the LED on the governor does not glow, flip the magnet
over and try again. When the LED glows mark that side of the
magnet as active.

❏

4. Determine and mark the active side of the remaining two

magnets.

Now you’re ready to begin the setup and test program.

Set Up Your Transmitter

❏

1. If your radio has a “hovering throttle trim” (an adjustable
trim operated by a dial that is used to adjust throttle position at
hover only), deactivate or inhibit the trim. This is not to be
confused with your regular throttle trim.

❏

2. Turn your ATV’s at both ends of your throttle servo to
100% (when instructed to do so, you will have to adjust your
throttle linkage mechanically because the ATV’s must be set at
100% for your governor to operate correctly).

Do not mount the governor in your helicopter until instructed
to do so. We recommend setting the governor up on the
bench before you mount it in your helicopter. This will make it
easier to perform the test procedures and give you a better
understanding of how the governor works.

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