ROTATING Mechanical micro-retract units (left and right)

Description

The Fun Scale Models CORSAIR F4U that Derek Micko designed is a beautiful scale model and since the landing gear on the full-size airplane rotates as it retracts into the wing, we were interested in creating the same thing.   It had to be quite small, lightweight, and simple – the engineering to accomplish this was quite involved. This micro-size mechanical retract is designed and manufactured by Rabid Models. Please read the following presentation carefully to understand the interesting features.

This video shows the prototype unit under development.

This video demonstrates the finished retracts installed on Derek’s Corsair.

The Rabid Models micro-retract is designed specifically for lightweight RC models – (less than one pound flying weight recommended) specifically, for the FSM Corsair but it can be used on other models.  For best results the wheels and tires need to be as small and light as possible.  Rabid Models offers the 2″ wheels and hubs for the Corsair. This package includes TWO retract units (left and right).

One unit weighs about 5 gms (without the landing gear), the frame is about an inch long and 3/4 inch wide.  Its ingenious design has only one moving part (the trunnion), and there is a wheel collar inside the trunnion with a grub screw which holds the gear leg secure and allows it to rotate. The wheel collar and grub screw are included.

The 3D-printed micro-retract is operated by a small micro servo and a Z-bend pushrod (not included). The plastic frame holds a trunnion (the moving part) which holds the landing gear leg and the trunnion has an attachment point for a pushrod.  We recommend using a 4.3gm metal-gear servo to operate each retract unit, which we offer here.

The retract frame is designed to be mounted on wood “rails” about 11.5mm (7/16″) apart.  You may use 4 micro-screws or simply glue it onto the rails using Foam-Tac.  The trunnion pivot requires a 12 mm length of 1/16″ wire. You’ll need 1/16″ wire for the gear leg and a smaller wire with a Z-bend for the servo pushrod. The activation pushrod can be operated from the left or right side.   Note: the 1/16″ wires are not included in the package!

The modeler will need to make careful adjustments in order to set the proper geometry and operation. The parts are very small and during use we expect the frame or trunnion may break under certain conditions.  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, and spare parts can be ordered if you need them.

Keep in mind that adding retracts to your plane will add some weight (retracts, servos, wire, wheels, etc.)  Fortunately these units are very light!

SPECIFICATIONS for the Rotating Micro Mechanical Retract:

Frame: 26 x 20.5 x 11mm, 2.0gms      Trunnion:  36 x 14 x 4mm, 1.8gms

5/8 x 4-40 Grub Screw, 1/16 wheel collar, and hinge wire: about 1.3gms

Frame and Trunnion Material: 3D-printed PETG Plastic.  You may select from different colors or paint with acrylic or enamel.

Tools and items required (NOT INCLUDED): 1/16″ drill bit with pin-vise, 1/16 wire for pivot and gear leg, 0.032″ wire for pushrod, and small screws or Foam-Tac glue for mounting.  The metal-gear micro servos and micro-pushrod connectors are available separately, as well as other items you may need for your models.

This product was originally designed by Derek Micko/Fun Scale Models and Rabid Models, Made in the USA. Copyright © 2024.