MICRO MECHANICAL RETRACT SET - with LOCKING trunnion

Mechanical retracts are operated by an external servo with a pushrod.  This small 3D-printed retract unit is designed with an "activation pin" which slides along a guide to mechanically lock the gear in the up and down positions, which means that the servo doesn't have to hold the gear up or down.

This item was NOT designed by Rabid Models.  This is "Landing gear retract rc V2" by user "cerro94" on Thingiverse:  https://www.thingiverse.com/thing:1418261 and is licensed under Creative Commons - Attribution.  Rabid Models modified the trunnion and is manufacturing & packaging the retract in a smaller size that's appropriate for relatively small & light model airplanes!

Please read this presentation carefully, as we are making different versions - please see the descriptions.  This retract is for the main gears only (not the nose gear).  2 retracts per set. The motion is designed to be parallel with the wing LE.

 Option A and B are the standard 90-degree retract for straight wings, pick the gear leg size - 5/64" (2mm) or 1/16" wire

 Option C, D, E are for wings with dihedral.  The 85-degree angle is for wheels retracting inwards, the 95-degree is for gear retracting outwards, like for a B24 bomber.   NOTE: the range of motion is still 90 degrees!  Pick the size gear leg size - 5/64" (2mm) or 1/16" wire

1) The locking retract is intended specifically for LIGHTWEIGHT RC models (less than one pound flying weight). For best results the wheels and tires need to be as small and light as possible. The retract uses 5/64" wire (2mm) or 1/16" wire for the gear leg.  You need to supply the wheels, tires, and gear legs, as well as pushrods and servos to operate the retract.  These are not included - but we have a number of these items available in the Rabid Models catalog.

2) The retract is operated by a small micro servo and a pushrod (not included). The plastic frame holds a trunnion (the moving part which holds the landing gear leg) and there is an activation pin which must be attached to the servo pushrod.  Extra activation pins are included. We recommend using a 4.3gm metal-gear servos to operate each retract, or a single 9gm metal-gear servo to operate both retracts.  For best results, the servo speed needs to be reduced.

3) Specifications - The frame measures just over 1" long, 1/2" tall, and 9/16" wide. Total weight is only 3.6gm per unit. Its designed to be mounted between two mounting rails (balsa wood) that are 9/16" apart. The activation wire (servo pushrod) should be 0.047" wire, and the trunnion also uses 0.047 wire for the pivot axle.   The wires are not included - you will need 1/16" wires for the landing gear legs, and 0.047 wires for the trunnion pivot axles and the pushrods.  Some careful adjustments and "fiddling" will be needed (servo throw, endpoints, servo arm placement, etc.) in order to set the proper geometry and operation. The normal setup is for the landing gear to fold in towards the fuselage with the servo mounted towards the center of the fuselage.  For the retracts to work properly we recommend operating the servo at a reduced speed. 

Please NOTE: The parts are very small and we expect the activation pin or trunnion may break under certain conditions (hard landings). The retract case may also break! Dear customer, please realize that its preferrable for the retract to break instead of breaking the wing! Split plastic can be carefully fixed with CA glue, however we also offer spare parts if you need them.  The package includes some extra parts.

This item as sold as a PAIR of 2 retracts. We've made a short video showing how it's put together and how it works. The video shows a slightly larger version of the product made for development. Here is the link: https://youtu.be/x82LlIS1B7A

                     Showing "UP" and "DOWN" (without the gear leg)

Tools and items required: 1/16" drill bit with pin-vise, 0.047" wire for the trunnion pivot axle and activation pushrod, 5/64" (2mm) or 1/16" wire for the landing gear leg, small metal-gear servos, micro-pushrod connectors, small screws or Foam-Tac glue for mounting, CA to glue in the gear leg and the activation pin. These items are NOT included but Rabid Models offers micro metal-gear servos and micro pushrod connectors, and CA and Foam-Tac glue separately.