Curved Fuselage Panels From Foam Poster Board

Hi Guys,

This is the article I mentioned about making curved panels with foam poster board.  I am still working out methods but this is what I have so far.

FIRST ATTEMPTS:

The first attempts at making curved panels were just working with a couple of scraps:

I scored the backs with a fingernail and then hand formed the curves.  I used a magic marker to help form the one below.

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Let's see if this works for real,,,

RAPTOR TOP PANELS:

I have made my first attempts on an actual project here.   I formed some curved top fuselage panels for the 24" F 22  Raptor that I had made bottom fuselage panels for earlier.

The first piece was the one with double curved sections and a flat piece between that was to fit between the rudders. I started by cutting a piece the right size allowing for the curves.  I then made 50% cuts to define straight and curved parts. Thus:

Next I removed the paper backing on the two outer sections and made knife scores about 1/8" apart along the lines of the bend.  As I expected, this allowed those areas to be formed into curves pretty easily.  I used a smear of hot glue to lock the curves into place.  Not too much.  The exposed foam melts pretty easily.

Scoring. 

Hand forming is easy with the score cuts.

The edges were back-cut and sanded smooth.  Then hot glue was applied to both edges and the middle flat spot.  Carefully hold the edges down while pushing the flat center down into place.  Hold everything and fine tune as the glue takes hold.

The end result with rear notches like the real thing.

A similar method was used for the one piece front fuselage panel.  The middle flat spot and rear curves were made the same way.  The rough piece was made to fit with about 1/4 over on all sides and then shaped.  The scores on the back were flared to match the tapered shape (about 1/8" apart at the back edge and closer to 1/4" at the front.  I also made cross cuts from the front tip to about 3/4" past the front angle so the piece could bend the other way.  The back edges were formed and stiffened with a smear of hot glue before final fit.  The front edge was left pretty flat.  Everything was back cut with a knife and then the perimeter was traced.  The piece was trimmed to the final fit and then the back cuts were sanded to a fine point and to lay flat. After checking the final fit I marked the position and then glued one side.  I as able to lift the second side to apply the glue to it.  It was a little tricky to get the very edges of the tapers glued down.  I had to squeeze a little hot glue into the joints after the main glue dried..  Doing this helped to roll the leading edges down which was a plus.  I had one spot where the glue skinning on the back deformed the panel slightly (because I used too much) but overall I am happy with the results.  If it was perfect I would have nothing to improve upon next time.

Notice that the front edge of the flat part behind the slot rests on top of the blue foam to help establish the shape.  It is glued down to the wing at the back.

I may rework the lower fuselage panels before I am done.  They look too squarish now.

That blue foam nose is also bothering me...

Check back for my updates.

Happy building!

Update:

I have added the curved panel cockpit...

This was made from 4 panels and was tedious to fit. I found that the panels form curves easily by pulling over a table edge using light hand pressure.  I did foam side down then had more curve than needed.  The last piece was hard to place before the glue set so there are a couple of open seams.  I am planning to try the iron techniqe to seal them,  The only fold is at the bottom of the canopy  That was done with a curved back cut.

I also added a curved panel cone to form the mount and conceal the motor.  The mount is a piece of plywood just glued to the inside of the cone before gluing the whole assembly down.  The cone was formed by making closely spaced radial back cuts and then forming around a magic marker.  

After the iron work I am ready to paint and or fly.  Still waiting for suitable weather for both.

The whole thing:

Top side:

Botton side.

I added a softer nose to a previous project:

This is a flying wing that I designed to make an airplane to be made from one sheet of foam with no waste and no extra foam.  The original version has a smaller nose and is not a true floppable.  This version adds the material to make the nose and canopy to make it a floppable.  I have submitted a separate article on it.  It should be posted soon.

The prepared blank:

Here is the prepared blank before assembly.  The upper middle section has the paper removed fom the beginning of the curved area up.  It was pre-curved by running over a table edge foam side down with light and pressure.