Williams Brothers wheels

Before going over the retract installation, I first want to cover the topic of wheels. In order to properly fit your retracts, you'll need to get your wheels temporarily mounted so you can test alignment and fit in the bays as you cut them out.

I chose to go with the 5-1/4" Smooth Contour wheels from Williams Brothers Model Products. This awesome model specialty company has a great line of scale wheels of many sizes and styles. Their wheels are of very high quality at an affordable price.

The Smooth Contour wheels I am using have a very narrow profile like the FW190 requires for fit and scale appearance. I found the foam-filled rubber construction to be quite light for large scale wheels at 6.7 oz each. The hub is a very strong plastic, including the removable smooth cover on one side. Removing the cover you will find plenty of room for the wheel collars on the axle.

Speaking of axles, another nice thing with these wheels is that they fit the axle of the Shindin retracts perfectly as is. No need to enlarge the axle hole or even cut the axle length down to get the cover plate on. I highly recommend these wheels. To see these wheels getting some scale details added, click here.

Laying out the main gear installation

Now we get to the actual installation process... well almost. First I had to plan out how the gear were going to fit into the wing by checking the 3-views for proper scale position, while simultaneously trying to figure out if they would fit within the wing as such. To make a long story short, this proved to be somewhat of a challenge as I had to repeatedly change my plan as I went along. I'll explain more on that later.

Basically what I needed to accomplish here was where my retracted gear would position on each wing half so that I could get the wheels to fit entirely into the wing, and, so that the struts would present the proper angles when extended. I began by taping the two wing halves together and sketching out the silhouette of the retracts, wheels and gear door shape. The key points I needed to lock down were where the axle would hit in the wing and where the end of the air cylinders would position. These landmarks would establish positioning left, right, fore and aft, as well as determine the overall line the struts would lay within the wing.

After getting this layout as close as I could without actually cutting anything, I went ahead and used a Contour Guage to create a paper template of the forward airfoil shape where the gear blocks would mount. This would permit me to cut ply false ribs out later for gear bay construction.

"Hogging out the foam"

Now comes the "fun part"... removing the styrofoam for the retract installation. To do this, you need a hot wire that you can scoop or "hog out" the foam with. The best thing I have seen is just a common coat hanger. Some guys use a piece of it inserted into a soldering iron, which I tried with two different irons but didn't care for it. I just couldn't get the wire hot enough with a wire that was any longer than an inch or so. Therefore I ultimately changed over to using a blow torch and fashioned a few different burning tools from coat hanger wire for different cutting tasks.

The pictures at right show some of the foam removal process. Admittedly, it isn't real pretty at this point but it will all clean up fine later. The first thing I found out in doing this was that the gear and wheels were going to have to move back at least 1/2 inch into the thicker chord of the wing or else they'd never fit. I cut styrofoam out until I was coming out the top side of the wing nearly everywhere but still couldn't get the gear to fit down in all the way so I ended up moving the cutouts back away from the leading edge until they did.

However, this won't leave me any room for adding wheel well detail, and I still will have a challenge figuring out how to get the gear door down flush with the wing surface. I have a few ideas and will cover that topic later on another page. Suffice it to say, after cutting and fitting, cutting and fitting, and cutting and fitting some more... I eventually got the retract cutouts complete. I'll still have to open them up further to the shape of the gear doors later, but for now, this will do until after sheeting is complete.

Building the retract mounts

To build the retract mount area up, I cut the foam down to a recessed shelf which is about halfway down into the wing. I applied 1/4" aircraft ply to these shelves on both sides of the retract channel. I also used my template to make two 1/8" aircraft ply false ribs that would lay in on each side of the 1/4" ply shelves. These two false ribs had to be cut out in the middle to allow the retract air cylinder and upper struts to pass through them. One gets a "U-shape" cut out of the top and the other gets cut out of the bottom.

Both of these two false ribs also extend back to a 1/8" backup spar that runs 10" lengthwise in the wing, right against the backside of the 1/4" shelves. When all this ply is glued in place with polyurethane "Gorilla Glue" it forms a strong box that distributes stress over a large area of the wing. The spars and ribs go almost all the way through from top to bottom of the wing too. The Gorilla Glue foams up after a short while and fills back into any uneven surfaces or gaps in the foam giving you a rock hard joint even in the messiest of situations.

I then filled up the remainder of the gear bay with balsa blocks and sanded them down to the airfoil contour, flush with the wing bottom surface. When that gets epoxied in, you have a very strong and solid retract mounting foundation. Lastly I added some aircraft ply rails on top of the shelves to shim the gear to proper position/angle as well as provide more "meat" for the retract mounting screws to thread down into. I will be using 1" sheet metal screws to secure the gear to these rails.

Lastly I used a drill and my hot wire to cut a channel in each wing through the false ribs and across the wing back to the aileron lead channel. This new channel is for the two air pressure lines that will run from the retract cylinder to the air valve and system in the fuse. The installed pressure lines fit snugly down into a recessed channel now that keeps them just below the bottom wing surface. I will be using the Robart Deluxe Air System with the Medium Size air cylinder.