MICRO MECHANICAL RETRACTS – small and light

$0.75$8.95

RM-FSM Micro Retracts

Description

Modelers may install retracts on small R/C models using direct-drive servos as Derek Micko has featured on many of his “Fun Scale Models” park flyers.  Derek designed this micro-size mechanical retract so that modelers would have another option.  This item is manufactured by Rabid Models. Please read this presentation carefully, this product has some interesting features to explain.

The Rabid Models micro-retract is designed specifically for lightweight RC models (less than one pound flying weight recommended).  For best results the wheels and tires need to be as small and light as possible.

The 3D-printed micro-retract is operated by a small micro servo and a pushrod (not included). The plastic frame holds a trunnion (the rotating 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 one retract, OR a single 9-gm metal-gear servo to operate two retracts at the same time.

The retract is about the size of a US quarter coin, to give you an idea. Its really small. (The quarter is not included!)

The retract frame is designed to be mounted on wood “rails” about 8mm apart.  You may use 4 micro-screws or simply glue it on using Foam-Tac.  The trunnion pivot uses a 9 mm length of 1/16″ wire (1.6mm). You’ll need 1/16″ wire for the gear leg (example below), and smaller .032″ wires (0.8mm) with a Z-bend for the pushrod. The modeler can install different length wire gear legs as needed.  The activation pushrod can be mounted from the left or right side.   Note: the wires are not included in the package!

The modeler will need to carefully install the retract in order to set the proper geometry and operation. The 1/16″ wire gear legs are installed last, they are simply pushed into the trunnion and glued using thin CA.  The parts are very small and In time 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.

Please check this short “live action” video (CLICK HERE) demonstrating the basic operation. Note the small Z-bend.
This video (CLICK HERE) shows a CAD animation with a few different angles.  You can see that the pushrod can be used from either side.  Towards the end there is a pop-up link where you can also watch a CAD animation of the nose gear!

DESIGN NOTES – THERE ARE TWO VERSIONS AVAILABLE!

“Version 1” is 18x20x12mm and 1.7gms. The trunnion has a very small tab attachment which is delicate. This unit is meant ONLY for very small models, say 8-12oz flying weight. V1 is supplied with an extra trunnion since its easy to break the tab. On a small model you could operate this with our small 2gm servo. V1 is printed in orange.

“Version 2” is slightly larger at 20x23x12mm and 2.1gms. The V2 trunnion has a larger tab which is much more robust, but we still recommend the 0.032″ pushrod. This unit can be used on larger models, about 16oz flying weight.  V2 is printed in gray.

There is no “shock absorber” – the 1/16″ wire has sufficient “spring” for the intended use. The main gears are designed to retract towards the fuselage or wingtip, not to the rear.

Both versions are meant to be mounted between wood rails with the trunnion projecting from the bottom of the model’s wing.  There is a 90-degree range of movement.  The customer can achieve a larger range by trimming some of the plastic from the frame.

ALSO – we have a “nose gear” unit which has the trunnion on the opposite side – the frame is mounted on a flat surface (for example on the back of the motor firewall). The nose gear unit is taller and slightly heavier than the main-gear units.  The nose gear retract is not steerable but its possible to make it steerable with a little ingenuity. (Contact us for details).

This product could also be used to open speed brakes or other control surfaces!

Prototypes shown here! V2 will be offered in a gray color. They are paintable. Adding retracts to your plane will add some weight (servos, wire, wheels, etc.)

The main gear micro-retract is $8.95 for a set of TWO units.

The nose gear micro-retract is $4.95 for ONE unit.

Replacement trunnions are available separately for both versions.  V1 and V2 parts are not interchangeable!

These 2 pictures show V2 on the left, V1 on the right

The next picture shows the V2 “nose gear” retract, which is designed to mount on a flat plate instead of between rails:

SPECIFICATIONS for the Micro Mechanical Retract:

Version 1: 18x20x12mm, 1.7gms      Version 2: 20x23x12mm, 2.1gms

Material: 3D-printed PETG Plastic    V2 is printed in gray.

The retracts are paintable, you may use acrylic or enamel.

Tools and items required: 1/16″ drill bit with pin-vise, 1/16 wire for pivot and gear leg, 0.032″ wire for pushrod, thin CA, small screws or Foam-Tac glue for mounting, servos, and micro-pushrod connectors.  These items are NOT included but Rabid Models offers CA and Foam-Tac glue, micro servos and pushrod connectors separately.

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

We’re able to modify this product and produce it in larger sizes (custom measurements) and various colors but its not for large models. Contact us for details.

 

Additional information

Weight .1 lbs
Dimensions 1 × 6 × 9 in
select type

Version 1 18x20mm TWO MAINS, Version 1 One Nose Gear, Version 2 20x23mm TWO MAINS, Version 2 One Nose Gear, V1 replacement main gear trunnion, V1 replacement nose gear trunnion, V2 replacement main gear trunnion, V2 replacement nose gear trunnion

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