Author Topic: De Havilland D.H. 88 Comet 1:32  (Read 4270 times)

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JeffH

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De Havilland D.H. 88 Comet 1:32
« on: January 05, 2011, 03:52:14 PM »
I finished work on the 3/8" = 1' (1:32 scale) DH 88 Comet model over the New Years holiday.

The model is supposed to represent the D.H. 88 Comet flown by Jim and Amy Mollison in the England to Australia race.  It was based on a not very accurate three-view found on the Flight magazine archive.  Later I discovered the much better Aeromodeller plans posted elsewhere on this site and used those to get some of the details right (Thanks for posting those, Mr. Marsh!).
The work in progress photo shows the Flight magazine plan in the background.  The fuselage is pine, the wings are wood from a discarded dresser and the nacelles are basswood.  I later made better spinners than the ones shown in the work-in-progress photo.  The metallic effect on the spinners/propellers in the completed model photos was attained by first painting them gloss white, then Krylon rattle-can chrome silver followed by polishing them with Rub 'n Buff Silver Leaf paste.  

The wood grain was sealed using multiple coats of polyester resin (as used in fiberglass construction) and sanded with progressively finer grits of sandpaper, ending with wet sanding with 2000 grit paper.  Control surface outlines were engraved using a rotary tool and panel lines were added using a sharp hobby knife.
The propeller blades are from a thick plastic material (styrene?).  The wheels and spinners are from wood (clear aspen) turned on a drill press using a decapitated wood screw to hold the wood blank in place.  The landing gear struts, wheel well covers and tail skid are from brass rod and sheet.  The navigation lights are from translucent plastic drink stirring sticks.  The saddle fairing around the tail was represented using thick enamel paint.

After reading "Aircraft in Miniature" by W.O. Doylend, just painting on the canopy seemed inadequate.  I used casting resin to create a clear canopy as shown in the photo below.  I first waxed the model surface then built up a mold out of Durham's Water Putty patching material.  After prying the mold off the model, I closed up the open end with cardboard and filled the mold with the casting resin (from a craft store).  The completed casting is next to the model in the photo; a spare mold is in place on the model.  I also tried making a mold out of plaster (seen behind the model), but the Durham's was easier to work with.  After cleaning up the casting I ground off the original wood canopy, painted the exposed wood a metallic gray and glued on the casting using super glue.  The clear nose piece was made by plunging the model into a blob of modeling clay, then filling the depression in the clay with clear epoxy.  The epoxy casting was then cleaned up and attached to the model similarily to the canopy.  After the model was painted, the canopy framework was represented using strips cut from black decal material.  ("Aircraft in Miniature" has been out of print for decades, but I was able to borrow a copy through inter-library loan.  The good folks in my town were able to track down a copy in the Santa Monica Public Library in California).

I painted the model using Testors gold and gloss black enamels shown in the next photo.  To thin the paint for airbrushing, I first decant the paint into the shot glass then add lacquer thinner and Metalizer sealer until the paint is thin enough for spraying.  I'm not sure if the sealer makes much difference; I read somewhere it makes enamels spray better.  The airbrush I used was purchased at a Mills Fleet Farm store (a north-central US based farm supply chain).  The airbrush has the unlikely (for an airbrush) brand name of "Dura Block" and they cost about $35.00 (less when on sale).  I had no problems with it.  I like the fact the paint reservoir comes with a metal cap; no more spilling paint all over!  As to why a store that sells horse feed and shotgun shells also sells dual action gravity feed airbrushes, I have no idea.

I've found punch & die sets useful for making disk shapes from thin materials.  On this model the silver thingys on the nacelles (representing cowling fasteners) were made from thin metal from a disposible pie tin; the wheel hubs are the same stuff.  The circular parts of the propeller logos are punched from white decal; the round ends of the spear trim were masked using circles punched from frisket film.  The punch & die set on the right is one I made years ago.  It consists of a metal base plate and plastic guide piece (from two rectangles of clear acrylic epoxied together); the punches are the shanks cut from a cheap set of drill bits using a cutoff wheel in a motor tool.  The home made punch and die still works; I used it to make the plastic disks (from a For Sale sign) in the foreground.  If making your own punch 'n die set, beware it is critical the holes line up exactly (use a jig or bolt the metal/plastic pieces together), and the faces of the punches must be perfectly flat.
The industrial punch 'n die on the left is from Harbor Freight Tools; the one in the middle was ordered from an on-line retailer.

I used Inkscape drawing software to make the markings.  I printed the outline style G-ACSP directly onto frisket film and then cut on the outlines to create masks for the large registration markings on the wings.  The "Black Magic" and G-ACSP on the fuselage were printed onto water slide decal film using an old Alps printer with a gold print ribbon.  The flag and "63" on the tail were printed using an inkjet printer.

The stand is from stained and varnished pine.  A piece of stainless steel welding rod holds the model up.  The label was made using MS Word and printed onto photographic paper which was then laminated between clear packaging tape and double sided tape and attached to the base.
« Last Edit: January 06, 2011, 06:14:37 AM by JeffH »

lastvautour

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #1 on: January 05, 2011, 04:40:19 PM »
Excellent workmanship Jeff. Your models are always a treat to see. I will post a picture in the 2010 Model of the year album.

JeffH

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #2 on: January 05, 2011, 04:48:45 PM »
Thanks, Lou!

The D.H.88 was a fun project, and for the most part it turned out the way I envisioned it before I started.

Jeff

Ken Pugh

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #3 on: January 06, 2011, 07:10:58 AM »
Well done with a beautiful finish.  I never thought of printing directly to frisket, good to know it works.

Ken Pugh

JeffH

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #4 on: January 10, 2011, 11:26:33 AM »
Thanks, Ken.

Ink doesn't stick to frisket film very well, so give it ample time to dry, and then be careful not to smudge the ink when cutting.  After cutting the design out, I wipe off as much of the remaining ink as possible so it doesn't end up on the model.

Jeff

Ken Pugh

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #5 on: January 10, 2011, 05:31:00 PM »
Thanks for the tip, I will definitely keep that in mind.  Have you tried give it a quick spray of clear coat like we do with decals?

Ken Pugh

Fingers

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #6 on: January 10, 2011, 09:36:08 PM »
Gorgeous piece of craftsmanship!

jim

JeffH

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #7 on: January 13, 2011, 11:39:23 AM »
Thanks, Jim.

Ken - regarding spraying a fixative on inkjet printed frisket film:  I haven't done that before, but I'll have to give that a try on my next model.  Sometimes it can be difficult to get all the letters cut out without smudging the ink, so it could prevent some aggravation.

Jeff

Peter

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #8 on: January 13, 2011, 12:17:48 PM »
Ok I have to ask a new guy question! what is frisket film?

Balsabasher

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Re: De Havilland D.H. 88 Comet 1:32-How to use Frisket film
« Reply #9 on: January 13, 2011, 03:09:19 PM »
Frisket or Frisk film is a universal product which has many diverse uses,firstly it is very low tack which means that it does not pull the paint from the surface,the adhesive is a patent product,you buy it in rolls or sheets of semi clear film which has the ability to take a lead pencil mark although a grease pencil ( Chinagraph or even eye shadow products work well ) you can see through it to trace images that can be cut out with a craft knife first onto a self healing board then transferred to the model or surface if used as a template,the edges are very clean cut enabling it to be smoothed down onto the surface with a pencil eraser which is very gentle,once applied it can be sprayed/painted right up to the edge and removed either straight away or when fully dry.
A tip when cutting out the design is to leave a membrane of film between the lines,once applied to the model it is a fairly easy task to make small cuts to release the membranes holding the delicate small patterns.
To see the full effect of frisket film study how the custom car auto sprayers handle this versatile material,they lay mask upon mask building up subtle edges or clean cut lines,another method is to apply the film first over the entire area and then mark the design with a sharp pencil,next withn a sharp scalpen cut straight into the film just enough to break through and at the same time leave a tiny cut into the wood,this has the effect of a double masking barrier as the paint flows up to the line and slightly into the groove,once the film has been removed a really clean line ensues,subsequent layers of colour an be built up starting with the lightest first,for example a white cheat line with red inner would be tackled 1/ mask the white,2/ spray the white 3/ mask the red inner 4/ paint the red inner line.
Roundals and ntional markings are a dream to do with frisket,a standard red/white/blue RAF roundal would be 1/ Cut outer diameter of roundal into frisket 2/ lay on the white base coat first leaving the outer ring in place,then add a disc of secondary masking by adding a frisket disk to cover the white where the blue goes,spray the blue,now make a disc to cover all of the roundal except the centre red portion,spray the red then remove the last mask to reveal a crisp roundal,masks can be used multiple times to do the other roundals,lay the frisk masks onto a piece of glass while you are using them,if you want to save them stick onto a piece of silicone paper or athick plastic polythene bag.
To make decals from frisket first apply a quick flash of artists fixative ( sold in art shops for fixing pastel drawings ) allow to dry and this is your base coat to allow the paint to go on easily.
Although frisket will not in theory take a compound curve you can around this to some degree  by applying gentle heat to the film as you apply it say around a cockpit area,I stress gentle and use a model makers heatshrink gun and not a domestic air drier ! far too fierce in use.
As always try any experiments on an inconspicious area of your particular model first before proceeding with the model itself.
Barry

Ken Pugh

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #10 on: January 13, 2011, 04:53:22 PM »
Sounds like a good idea may be to spray the frisket area with clear, print the design, spray again, then cut out.

Ken Pugh

Balsabasher

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Re: De Havilland D.H. 88 Comet 1:32
« Reply #11 on: January 13, 2011, 05:10:38 PM »
Thats it,trap the image between two layers of clear material Ken.
Barry.

Balsabasher

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Re: De Havilland D.H. 88 Comet 1:32-Home brew decals again
« Reply #12 on: January 13, 2011, 05:18:22 PM »
Another good way to make homemade decals is this time proven one-
Obtain some sticky back luggage labels or parcel tape,not the self adhesive type but the old 'Licky sticky' type,paint on a layer of clear varnish,when dry print or paint your decals,I use those circular draughtsmans tools building up the circles etc,add another coat of clear varnish,once dry soak off the decal in warm water just like any other waterslide transfer,it works but as the carrier film is more fragile hold the edge of the decal against the model and pull the backing paper slowly otherwise you can get pesky wrap around of the wet decal.
Yet another way is to use invisible sellotape,it is crystal clear and takes paint,cut out and add to the model protecting with a layer of clear varnish,it works remarkably well.
Barry.