Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
So why leave those foam wheel well's undressed.
I will attempt to show how I dressed out the wheel well's on a project that I am working on in a chronological order, with explanation's to each step.
This is nothing new to the old timers... but hopefully will benefit some of the newbies coming into the hobby.
We will start with a pic of the objective... which is basically a raw cut out in the foam of the outlined wheel well opening. This is done after you have laid out your markings on the sheeted surface. The sheeting is then cut away to expose the underlying foam.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
The next few pic's are the tools needed to lay the groundwork for the finishing process.
First pic shows a soldering gun with a hot wire tool made from .070 music wire. The wood attached to the wire acts as a depth stop/guide. The O.D. width of the wire in my case was .920 which was arrived at by that being the width of the channel that the retract strut will lay in.
All cutouts were made using this tool except for the rib channels that support the retract frame. Those were milled out with a router.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
Since the hot-wire method of removing the foam is a rather crude form of getting the job done; we need a method to fine tune the opening before gluing in the sheeting.
The tool in this pic is nothing more than a PVC pipe reducer that can be found at any plumbing supply house & most hardware stores. You want to find one that is the diameter of the wheel well opening that you want to achieve. If you can't find the exact diameter, go to the nearest smaller size.
The tool will serve several functions. One is to clean up the bottom of the wheel well "Wing Inverted", and to also clean & true up the walls of the wheel well. It will also act as a form for shaping the 1/32" ply that will line the wall.
In my particular case, the large end of the PVC reducer is 3 1/2" O.D. First thing to do was to cut/sand to shape a piece of 1/4" aircraft ply to the large end of the reducer. To this ply, I attached a piece of 80 grit self adhesive sandpaper for sanding the base of the wheel well.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
This pic is the same tool with the circumference wrapped several times with self-adhesive 80 grit sandpaper. In previous post I mentioned that if you can not find the exact PVC size... to go smaller in diameter.
Now you can wrap the sandpaper tightly around the PVC reducer several times to achieve the diameter that you need. The object is to get a snug fit going into the opening, and by gripping the small end of the PVC reducer, start the tool by rotating it back and forth in the opening. Sand a little then remove the tool and vacuum any dust out. Keep repeating until you get a nice clean vertical wall in the opening. Once you reach the base of the opening the 80 grit that was glued to the bottom of the PVC reducer will clean & true up the bottom of the opening.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
This is just a small balsa block with 80 grit self-adhesive paper applied to it. This is used to clean up the narrow cavity that forms the channel for the retract strut.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
Once the sanding operation is done, remove the sandpaper from the PVC reducer. It now will become a form tool.
Using 1/32" ply, determine how long and wide a section you will need to line the inner circumference of the wheel opening. Cut so you have a little more than you need in both length & width. Once your piece is cut, wet it on both sides with a 50/50 mix of ammonia & water. Wrap this tightly around the PVC form and hold the edges with mini clamps or tape.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
Remove ply from PVC form tool and this is what you should have. The ply will hold most of it's curved form.... there by making it much easier to glue in the wheel well.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
We want to make a template for the 1/32"ply that will make up the floor for the entire retract opening. Remember, the floor is actually just beneath the upper skin. We are just viewing the wing inverted.
For making the template, I used a product called See-Temp. It is clear and can be viewed through to the back side. Cut a section large enough to cover the entire opening and tape the edges down. Now draw out the outline of the opening onto the See-Temp material using a Sharpie pen. Remove the See-Temp and using either a pair of curved scissors or sharp #11 x-acto, cut the template to shape.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
The pattern is cut, locate a piece of 1/32" ply and secure the template to the ply by holding firm pressure with your hand, pressing it out flat against the ply. Trace the outline of the pattern onto the ply using a #2 pencil.
Once done, cut the ply to shape same as you did the pattern.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
Place the piece you have just made into the retract/wheel opening and check the fit. You will most likely have to fit and sand several times to get an ideal fit. You want a good tight fit at the base, even if it means the ply has to be lightly forced into the bottom.
Once you are satisfied with the fit, remove ply and coat the glue surfaces with glue of your choice. Just make sure it is compatible with foam. Epoxy "30 Minute" or Tightbond are two good choices.
Place the ply back into position and using small weights, weight the ply down. Let this cure before proceeding.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
Once the ply floor is installed, we need to proceed to check the fit of the piece that will line the wall of the wheel well.
"Note" that I mentioned earlier that we wanted to cut this section a little longer than needed. In the attached pic, you can see that the ends extend into the strut channel opening. The purpose of this is to allow for a tight butt joint with the ply that will line the vertical walls of the strut cavity.... which you will see in the next few posts.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
In this step, you will need some way to hold pressure against the ply to press it against the vertical walls of the opening while the glue dries.
Some people have used blown up balloons to achieve this, but as you will see in the picture; that my method consist of using a roll of dry-wall patch material and a wood wedge. I have one corner in the wheel well that is elongated to clear the scissor links on the strut... therefore the need for the wedge.
Once you are satisfied with the fit of the ply, remove and apply glue as before to both the ply and foam. Reinstall your ply and hold in place by your choice method until glue dries thoroughly.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
We need to measure and cut the 1/32"ply that will line the walls of the channel for the retract strut. These should fit tight to the lower ply, and wedge tight into the corners of the ply that lines the opening.
In the above pic, you can see that a balsa block is used to hold these firmly against the walls until the glue sets.
Once everything is dry, remove wedge blocks and sand/blend the corners where the wheel opening and strut channel meet. Also sand the vertical edges to be flush with the wing sheeting.
Fill any voids with light weight filler & sand to blend. Attached is a pic of the finished product of your labor.... sans covering.
Posts: 1510
Joined: 12/17/2001 From: Lawrenceburg,
KY, USA Status: offline
One more pic of the finished wheel well.
I hope someone get's some benefit from this. It has taken me longer to take the pics, crop & resize, and write Captions than it has taken for my wife to drive from Kentucky to Flat Rock Michigan. She left at 10:00 AM... now 4:00 PM
To all you guy's that write how-to article's.... if I wore a hat, it would be tipped your way.
Printable Version
All Forums >> RC Airplanes >> Tips & Techniques >> You wouldn't take your wife/girlfriend out naked now would you... 
You wouldn't take your wife/girlfriend out naked now wo... - 
RE: You wouldn't take your wife/girlfriend out naked n... -