Aileron Gyro.
Installation of a gyro on the aileron axis can provide a high degree of stabilization to wind.  Wind mainly moves in the horizontal plane.  This affects the airplane often by lifting one wing up and over causing instability in the attitude and heading of the airplane.  Often this is realized in crashes during landing and take off. The time where most crashes occur.  On this page I will go over the basic step by step the installation of a gyro on the aileron axis of an airplane.

IMPORTANT: You should install the gyro onto a plane that has been test flown and trimmed out FIRST before installing the gyro. You should MECHANICALLY adjust the trims on your airplane using linkages or repositioning the servo arms to be centered.  Remove all Subtrim and trim from your airplane and keep mechanically trimming the airplane before moving further.

1) Choose and purchase a gyro.  I recommend the Detrum GY48V gyro from Hobbypartz. This gyro is easy to mount because it is square with flat sides. It also requires no modifications because the gyro is held well inside the case and the cables are strain relieved.
2) Mount the gyro on or inside the plane with the label facing forwards or rearwards (Assuming you have a Label UP gyro like the GY48V. If you don't then follow the following drawings: Label UP, Label Sideways. Based on the table in the LINKS PAGE. When mounting, you should mount it in a way that isolates it from vibrations. In most electric planes, simply mounting it into the fuselage near the wing is fine.  For Nitro planes, you may want to use several layers of gyro tape.  In general, I recommend using 3M indoor/outdoor foam tape.  It is Gray with red release film and sticks great over time when you apply with pressure.  If you have a foam surface, epoxy a metal or plywood plate to the foam to secure the gyro. DO NOT VELCRO the gyro to the airplane.
3) All gyros will have a male and female servo wire. Plug one end to the Aileron channel of the Rx and the other to your aileron servo. If you have 2 servos, use a Y harness to connect the 2 aileron servos.
4) Many gyros will then have a gain wire plug. To tell the difference, most will have only 1 wire on them or a different color connector. In any case, the gyro instruction manual will mention this. Connect this to your Gear Channel or Flaps Channel (gear channel will be explained further here).
5)  Initially set the Travel adjust (endpoint adjust or ATV) for the Gear channel to 100/100.
6) Power up the plane but once you power it up, DO NOT MOVE THE PLANE until the gyro has initialized.
7) Set the gyro to RATE mode using your gear switch (most gyros with a gear gain wire will indicate the RATE MODE by turning the LED off, such is the GY48V).You know your switch is set to rate mode because the control surface will always return to center after you move the stick. If it does not return to center after moving the stick then releasing, then it is in heading hold mode.
8) Verify your gyro reverse setting is correct. Lift the right wing quickly and the right aileron should lift as well. If not, flip the REVerse setting on the gyro. If the gyro has no reverse switch, it will have to be flipped around (face label in opposite direction while maintaining the same direction of the wires). Here is a page on testing the gyro reversing. Your transmitter Aileron channel should not have to be reversed because you flight tested the airplane before installing the gyro right? :)
9) If your gyro has a gain setting allowing you to control the rate/heading hold mode gain, set the Rate mode gain to 30% for your initial flight. Do this by keeping the Gear switch to Rate mode, then decreasing the Travel adjust (endpoint/ATV) to 30.
10) You can either set your Heading Hold position gain to 30% or set the Heading hold position to Rate Mode/Zero Gain which will basically set the gyro off.  To do so, set the Heading Hold switch position Endpoint to 0.  Now, adjust the sub trim of the gear channel until the gyro LED (indicating Heading Hold) just goes out. 2 more clicks in the same direction you went to turn it off and now your done. Notice how in the OFF position, moving the wing does not affect the ailerons.

Once again, I recommend you do your initial test flights with the Gyro in RATE mode and about a 30% gain. This should allow for some stability with a very low chance of oscillation.  If you do get some oscillation, you will simply slow the plane down and land.  Oscillations with a gyro on an airplane typically get WORSE the faster you fly so look for them in a high speed dive.

When at your maiden, remember to not disturb the plane after you power it up.  Then do a control surface test as well as gyro test before flight.  Move the sticks to check the ailerons.  Then lift the wing and verify the control surface goes up. When you fly it, do a high speed dive starting from a safe altitude. If the ailerons wiggle at any time, turn the gain down.  If you feel you want more stability, turn the gain up.

The following is a video showing the installation of a LABEL UP (Detrum GY48V) gyro installed into the Ailerons of an Airfoils Depron Profile foamie. This gyro is in RATE MODE and has a gain wire.

The following is a video showing the installation of a LABEL UP (Esky 704) gyro installation onto the Ailerons of a Hawksky. NOTE: This gyro is RATE MODE only and has no gain wire.