Posts: 106
Joined: 8/28/2006 From: San Diego, CA, USA Status: offline
I am starting a new fiberglass project that will involve plug construction, molding the plug and pulling parts from my molds. Over the next few months I will do weekly postings to act as a basic tutorial for fiberglass molding. That being said, this represents my initial post.
I have made many things out of fiberglass over the years. Typically, my projects involve building a plug, making a mold from that plug and finally using that mold to make pieces.
One project that I have wanted to do for a while was inspired by a ceiling fan that I first saw years ago. I am sure that you have seen the fans that look like the nose of a WW II fighter plane. From the moment that I saw that fan, I thought that it would be cool to have a helicopter body that would hang from the underside of the ceiling fan making the fan blades look like rotor blades. Of course the helicopter would have to be a classic – I chose the UH-1 from the Vietnam era.
Thus the project begins. The first thing I like to do when I am building something like this is to go to the hobby store and pick up a model of the helicopter that I want to build. I use this model as a three dimensional reference. While 3D references are not always available, I do like to use them when possible. For this project, I selected a 1/35 scale UH-1. Using this model, I can get a good idea of the size that the fuselage has to be relative to the diameter of the fan blades in order to maintain a scale appearance.
I began to build the fuselage of the model and began to analyze the proportions, angles and curves of the copter. See the photo of the fuselage below.
Posts: 57
Joined: 11/15/2002 From: Arlington, TX, USA Status: offline
Hello, My name is Nevin M. Levy also known as G17Staggerwing. I am looking forward to your progress and your posts on how you accomplish your tasks. I am very interested in doing fiberglass work and am looking forward to learning your procedures. I wouldd appreciate it if you could e-mail me as you progress just in case I might miss a posting. My e-mail address is: njlss5@aol.com. Thanx for your future tutelage Regards Nevin G17Staggerwing
Posts: 106
Joined: 8/28/2006 From: San Diego, CA, USA Status: offline
Getting on with the helicopter...
At this point, I can begin to produce profile drawings of the copter. I definitely need to start with a view from the top and a view from the side. Some of this is accomplished through artistic ability and some of it is cheating. The model that I bought had these views in the painting instructions. Based on the diameter of the fan blades, I figured that the fuselage should be about 40 inches from nose to tail. I simply used my copier to blow these views up to the size that I need. Then I drew in some details that were lost in the enlarging process. See the photos below.
The next step for me was to trace these profiles onto a base that I can use to build a plug. I like to use 1/8 inch mahogany door skin for this. I like mahogany because I can buy it at home depot for cheap and one sheet is more than enough material for a project like this. In the photos below you can see the cut outs that I did in the door skin.
You can see that they warp a little. This warping is no big deal since I will easily straighten the pieces out during assembly of the frame. Next, I want to decide along which line to epoxy the primary horizontal shape to the vertical shape. Having access to my plastic model makes this decision easy. In the photos below you can see how I glue two pieces like these. Angle aluminum stock is easy to clamp the pieces to and assures reasonable alignment of the parts.
In addition to angle aluminum making alignment of not so straight pieces easier, it also gives a pretty good 90 degree alignment of one piece to the other.
At this point I need to make a statement concerning scale. I am no artist, I know from the outset of a project like this that when I am done, anyone who knows anything about helicopters is going to look at this and say “Hey, that’s a Huey UH-1”. That is good enough for me. You can put as much talent and time as you wish into a project. This is your prerogative. I like to get a project’s detail to the point where I am satisfied. I think that I am usually satisfied with my projects bearing a close resemblance to the vision that I started with. That being said, nothing that I ever build will ever be completely scale (unless I happen to trip over a bucket of talent and patience)
Posts: 106
Joined: 8/28/2006 From: San Diego, CA, USA Status: offline
Now, I move forward with creating buck stations. A buck station is a guide that ensures that your plug is going to resemble what you want it to in the end. For this project I use the same 1/8 inch mahogany that I used for the initial profile pieces. My strategy for placement of buck stations is simple, I put one anywhere that I am concerned about maintaining the correct lines of my project. Usually I am of the opinion that more stations are better.
Another rule that I like when deciding how many stations to use is to make sure that my sanding block is longer than the span between the stations. I am going to fill the spaces between the stations with floral foam blocks and then sand the foam down to the level of the buck stations. The sandpaper will easily cut the foam down. If the sanding block is shorter than the distance between the stations it will create a depression in the foam. Not that a depression in the foam is enough to ruin your project, but it is enough to cause you more work in finishing your project.
In the photos below I have placed numerous buck stations on both sides of the copter fuselage. Make sure to measure all of these out when building a mirror image project. Another way to ensure symmetry of your project is to cut the buck stations for each side at the same time, if necessary, clamp the mirror image pieces together and smooth them with a sander to ensure identical shapes and epoxy the stations in place at the same time. These procedures keep you in focus and your project symmetrical.
With all of the buck stations in place, I can examine the two halves of this project for symmetry. It doesn’t have to be perfect, but it should be pretty close. Once I am comfortable with the symmetry, I can move on and start filling the two halves with foam.
Posts: 625
Joined: 3/13/2004 From: Vista,
CA, USA Status: online
Doc,
I have been watching this thread with interest. I have been working on someting like this and using a method very similar to what you are doing. My project is a 42" wingsapn Yak 54 for E-power (3-4 cell li-po). The difference is that I am using hard board. The stuff is cheep, but hard to work with, and I may cut the formers from wood (I have done the profiles and cruches from hard board)
I was planning to plank the thing with balsa, but may go with flower shop foam. I used CAD to generate the patterns.
Posts: 106
Joined: 8/28/2006 From: San Diego, CA, USA Status: offline
Foam works awsome. It is cheap, shapes exactly how you want it and it really speeds the completion of your project. This project is nearly done but my writing slows the posting process (not enough time) Here are a few pictures of what the copter looked like in the foam stage. I will get the full post up this weekend. I have used hardboard for builds in the past, I think I like mohagany door skin better. It seems to have many properties that make it easier than hardboard. Here are some pictures of the copter filled with foam and taking shape. All this was done in a few hours one afternoon. Very fast method.
Posts: 106
Joined: 8/28/2006 From: San Diego, CA, USA Status: offline
Thanks all for the kind words on my project so far. I have done many of these and it looks about how it should at this point. As far as glue goes, believe it or not I use bondo. It cures fast and penetrates deep enough to hold the foam during the shaping / sanding process. I try not to get bondo on any area of the foam that will need sanding. I will provide more information on this in my next post.
Posts: 106
Joined: 8/28/2006 From: San Diego, CA, USA Status: offline
This post in the build of this copter is short because I had no time to write this weekend and I covered some of this in a mid week post. Moving on, filling the voids with dry floral foam is easy. I simply push the foam into the forms in away that gives the best use of each foam block. When necessary, I use an adhesive to secure the foam to the developing plug. I love using regular automotive bondo as an adhesive. It holds strong, cures fast and is cheap compared to epoxy adhesives. The photos below show the insertion of the first few foam blocks.
I like to rough trim the foam with a blade to make it easier to work with. Trimming can be done with a sawing motion using any type of serrated blade. Usually I use a hacksaw blade – I couldn’t find it so I used this coping saw instead.
I continue placing more foam between the buck stations. This is my breaking point for my first session of foaming. Kind of looks like a mess but I am right on track.
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All Forums >> RC Airplanes >> Composites Fabrication And Repair >> Fiberglass How to: Plug to Mold to Parts 
Fiberglass How to: Plug to Mold to Parts - 
. Looks like I will have to wait for spring, its too cold to do this out in my shed .