In this post I am finally getting around to installing the Robart retracts for my rc airplanes landing gear. You will notice that the Robart retract is highly detailed with many scale features which will add to the scale realism of my beechcraft bonanza. First I thought it might be important to go over all the parts of retractable landing gear, in case some of you needed more specific information to understand how they work.
Let's go over how the Robart retracts work and what the parts of a retractable landing gear system entail – followed by the first steps to preparing the landing gear rails for installation.
In the following video you will see how an introduction to the Robart retracts and how to prepare the plywood landing gear rails for installation by cutting them to length and sand them and the ribs to fit properly.
Robart Retracts – These are the biggest component to the landing gear system. For this rc aircraft, I need three. Each Retract consists of a mounting plate to secure to the wing and nose of the plane. Each retract is made up of an air cylinder and piston that are actuated by air pressure. The landing gear uses a cam pin and cam follower to guide the retract and lock it in place when extended and retracted. These are very scale landing gear and even have spring shocks for the strut and and an oleo strut for the axle.
Look at the photo below to get an idea of how the retract looks and what each component of the gear look like as well. You can see the mounting plate, strut, wheel and air cylinder.
Air Tank Reservoir – An important part of the whole system. It will store the compressed air which will power the cylinders, which in turn will drive the piston to actuate the landing gear itself.
Air Line – This is flexible plastic tubing that is color coded for routing your air lines. It comes in 2 colors, red and purple. I will be using the red tubing for routing to the air port on the landing gear air port that extends the gear. The purple air line will be used for routing the air line for the landing gear retract air port.
Air Pressure Gauge – This is a handy device which shows you the level of air pressure in the air tank reservoir. If you will be utilizing a pneumatic landing gear system you might want to consider purchasing this device as it will provide a bit of insurance as to how much air pressure is in your tank. Not a bad idea when you can make a quick visual check and know whether or not you need to add air to your tank. This device will be hooked up between the air tank and your landing gear cylinders.
Speed Control Valve - An important part of the overall system. This will control the level of air that goes to the landing gear and how quickly or slowly the gear will retract and extend from the rc plane. Typically this consists of two valves to control the rate of air, also as part of the system it contains 3 air ports that the air lines will hook up to. These will be controlled by a plunger or spool that will be cycled by a servo and initiate the actuation of the landing gear cylinders.
Fill Valve and Fill Chuck – The fill valve is a one way valve that will be a part of the over all air line system. It is going to be connected through a tee. Later it will be mounted on the fuselage and the fill chuck will attach to it and fill up the air cylinder. The Fill Chuck is going to be part of the air pump and will attach to the fill valve when the air tank needs filling.
Retaining Rings and Tee Fittings – These components are what will be used to route the air lines cleanly and logically from the fuselage to the wings and landing gear air ports for the nose landing gear and wing landing gear respectively. The retaining nuts are the aluminum knurled parts shown below. The tee fittings are the red and black plastic parts shown below.
This is all the components that will be used to hook up the air system for the landing gear. I am going to be starting with installing the retracts in the wings of my radio controlled airplane. I will continue to create a series of step by step videos that details the installation of all these components. I have looked all over and there is no real books or videos on any of these parts, so that is why I decided to put this together.
The Next Steps
In my next post I will be completing the installation of the landing gear rails by gluing them into the wing. I am going to include some useful tips when it comes to gluing, so stay tuned for the video too.
Let me know what you think of all of these videos and detailed tips. Thanks for reading and watching.