Intro to Robart Retracts and Installing Landing Gear Rails

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.

 

Major Components

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.

red and purple tubing for landing gear air lines

 

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.

Speed Control Valve for regulating air pressure in a rc plane landing gear system

 

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.

Fill Valve and Fill Chuck connected for filling air tank for rc airplaneFill Valve and Fill Chuck for air line fillling for a rc plane air tank reservoir

 

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.

Retaining nuts and air line tees for rc airplane pneumatic air line system

 

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.

Filed Under: Latest Building Tutorial

Build RC Model Plane Wing Center Section

At this point I am ready to build the center section and add the balsa sheeting to the wing of my radio control plane, making balsa sheeting is easy when you follow a few simple rules. You can see the steps for this in the balsa sheeting post. Creating proper balsa sheets is one of the most important steps when it comes to a professional looking sheeting job.

Completing Center Section

As you can see here, I begin with an important step with any rc model plane…setting up the structure and aligning the parts perfectly to the plans. As always, I use a magnetic building board to build all my rc airplanes from scratch. If you get the alignment and layout right for your wing center section, then you will be buildnig like a pro too. Using a square and magnetic vises, I hold the center section to my sheet metal board.

Aligning rc plane ribs with square. Held in place with magnetic vise.

 

After confirming the alignment of the ribs, I can continue to add more magnets to hold the rest of the wing center section in place.

 

Center section rc plane wing ribs held in place with magnetic vises

 

magnetic building board with rc plane wing center section held in place.

 

 

 

Filed Under: Latest Building Tutorial

How To Keep From Stabbing Your Foot With X-Acto Tools

You might be wondering, what in the world is this possibly about and how could it possibly be useful with building rc airplanes. Well, if you are like a few of us builders, you already know what I am talking about. If not, then congratulations on being clueless about this topic.

I am referring to your hobby knives/X-acto knives rolling off your work bench and into your foot. Yikes!

 Yes, this happens more often than you would believe and I am here to stop it with a simple tool that will keep that from ever happening again (as long as you use it of course).

The good news is it does not require anything more than a few common household items to construct. Let’s begin….

 

Step 1. As you can see in the picture below, you will need the following items to build the tool that will forever save your toes.

  • Plastic Container – Don’t use your wife’s Tupperware, but instead use a plastic container from a food item. I used a plastic container from some kind of dip that was not memorable.
  • Bolts or other scrap metal – I used some stripped bolts that were no longer useful. In other words, use any scrap metal with some weight to it.
  • Styrofoam – Everyone gets packages or appliances, finally a use for that dense foam that insulates our landfills! Make sure your foam is thick enough and large enough for your container.
  • Glue – Foam friendly glue please. No CA glues. Either a white glue, or an all purpose glue, gorilla glue works very well.

Hobby Knife Holder made from plastic cup,bolts and styrofoam

 

Step 2.  Using your plastic container as a template, lay it on your foam piece (as shown below) and draw around the container. Now you want to cut out around the line you made, remember that your line is larger than the inner diameter of your container, but it is always better to be a bit bigger than too small. It is always tougher to put material back than to take it off.  You can use a hobby knife to cut it out, which may be a good idea as you won’t have Styrofoam bits flying around. Or you can use a saw (as I did) and cut out along the line.

Important note: If your container has tapered sides (like mine did), you need to take this into account when you get ready to shape it to fit.

cutting styrofoam for a rc plane hobby knife holder.cut foam with a coarse saw for a rc airplane tool that will hold hobby knives

 

Step 3. Sand and cut your foam piece to fit inside your container. If you do any sawing or cutting of foam, I recommend doing it away from your building area as bits of foam will stick to everything, gotta love that static electricity. You are looking for a snug fit (see picture below) so the foam will stay in place.

cutting and shaping foam for rc plane hobby knife holdercut and sand foam to shape to fit hobby knife holder for sharp rc plane hobby blades

 

 

Step 4. Place the foam inside your rc airplane hobby tool holder and see if it fits. As you can see here, it still needs some trimming to fit better. Be aware that we do not want the foam to fit all the way to the bottom of the container as we will have the scrap metal in the bottom to weigh down our rc airplane tool holder.

foam fitted into plastic container will hold rc airplane hobby knives.

 

Step 5. If you are sure of the fit, you can proceed with the last step, gluing it all together. As you can see in the picture below, you only need glue in the base of the container and there is a very good reason for this. The foam will eventually wear out from countless stabs from your X-acto knives, and you will want to replace the foam. You cannot do this easily if you glue the whole piece of foam in place. So remember to only glue the bottom of the foam and you will be able to remove it later.

filling bottom of plastic container with scrap bolts to weigh it down. glued in place too

 

Step 6. Poke a hole through the foam, either on the sides or through the middle. This will allow air to get to the glue and help it to cure faster. Now just wait a few hours and you are ready to start using your hobby knife holder, I mean foot saver.

finished hobby knife tool holder or x-acto knife holder for rc airplane building

 

This is what this hobby is all about, being resourceful with everyday items and creating useful tools from them. I have learned a lot of skills that I have found came in handy in other parts of my life. It is a great and rewarding hobby that always is exciting and teaching you something new.

I hope you found this post useful, and I would love to hear your thoughts. If you have an idea similar to this, please feel free to share it. In fact, I encourage it, so we can all spread the knowledge and share.

Filed Under: Home Made RC Plane Tools
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