ARBA 1/48 De Havilland 108 “Swallow”
Kit #CX069 High Speed Version

Images and text Copyright © 2003/2004 by Matt Swan

Developmental History
        The De Havilland “Swallow” aircraft were evolved to investigate the transonic region near the sound barrier with tailless aircraft. Three prototypes were built even though the aircraft was originally conceived as a half scale model of the proposed DH-106 airliner.
        The first two aircraft built were low speed airframes but the third was built with a longer nose and the pilot's seat was lowered for the fitting of a low-drag canopy. This increased the overall length to 26 ft. 9˝ in. (8.165 m). The aircraft designated VW120 was powered by a DH Goblin 4 engine of 3,750 lb. thrust (1700 kgp), did not fly until July 24th 1947.
        On April 12, 1948, the aircraft set a new 100 km (62.1 mile) closed circuit speed record of 605.23 mph (974 km/h), flown by John Derry, and it was certain that it could better the top speed of the preceding low speed airframes. On September 6, 1948, again flown by John Derry, the aircraft reached Mach 1.0 in a dive between 40,000 and 30,000 ft. (12192 m to 9144 m) without any buffeting or instability, only some tightening of controls. It became the first British aircraft to break the sound barrier and the first turbo-jet aircraft in history to exceed the sound barrier. Fifteen weeks later, a Russian Lavochkin La-176 broke Mach 1.0 to join the ranks of supersonic turbo-jets. The sound barrier had previously been exceeded by both the rocket-powered Bell X-1 (Mach 1.46) and the mixed power Douglas Skyrocket.
        The third DH.108 ended its career on February 15th, 1950, in a fatal crash near Birkhill, Bucks.

The Kit
        Alan Ranger and Bill Anderson (ARBA) produce these limited run kits in the Bigglewade, Bedfordshire area of the United Kingdom. Although they are not big producers of kits they are consistently putting out a trickle of high quality resin products and can still be found on the Hannants stand at the Duxford Airshows. This particular item is a multi-media resin kit that includes white metal landing gear, two vacuformed canopies, 15 resin pieces and no decals – this is the norm for an ARBA kit. The vacuformed canopies have a very rough texture to them and will require a lot of polishing to clean up. Fortunately there are two of them provided so if you screw up one you have a second chance or if you want to display the model with an open canopy you have lots of pieces you can hack up. The framing on the canopies is very light and will require some careful study when masking.
        The white metal landing gear are nicely cast and show good detail. I was very happy to see that the gear were of metal as this will be a very heavy model when completed and resin gear would definitely sag with time.
        The resin parts are quite interesting. The main fuselage is a solid cast part and all pieces show finely engraved panel lines. The pour stubs have been sawn off fairly close to the bodies but will still require a good bit of sanding. The oddest thing on the large pieces is that they appear to have been poured in two stages. The first stage being nearly 90% and then a second pour on top of that giving a weird definition line that is only visible to the eye and not detectable by touch.
        As I examine the parts I cannot find any defects such as micro holes other than one corner of the main fuselage right by the cockpit where it appears a single air bubble had been trapped in the mold. Not a serious problem and one that will easily be repaired. Compared to Czech Master Resin kits this would rate superior. The interior parts look good on a casual inspection but on close inspection the dash is not cast very well with lots of distortion in the instruments. I don’t really see this as being a big problem unless you plan on building the kit with the canopy open and even then you would have to be a member of the flashlight brigade to take notice of it.

        The instructions consist of a single page (front and back) of typed directions and a multi-view drawing showing marking placement. Remember – there are no decals included with this kit so you must either paint the markings or provide them from alternative sources such as the spares box. Odd thing about the directions is that they speak quite a bit about the low speed airframes and picture the taller canopy for the craft but the kit does not include that canopy or the anti-spin parachute fairing illustrated on the sheet. Considering that there was a size difference between the two craft and the lack of these parts the modeler is pretty much confined to building the high-speed version only. They do include a brief history of the “Swallow” and gives the modeler a fairly good idea of the proper order of assembly.

Conclusion
        This is an unusual aircraft, there can be no question of that and it represents an important branch in the history of the race to break the sound barrier. The overall quality of the kit parts is very high and it appears to be a fairly easy model to build. The biggest problem facing the modeler is simply finding one to build.

Construction

2/3/04
       She certainly looks to be an easy build with few parts so let’s see if that holds up in application. I spent several hours removing casting stubs from the main fuselage pieces and sanding the facing surfaces smooth. I cleaned up the instrument panel and the seat and did a quick test fit. The seat drops into place nicely but the instrument panel must have been designed for a different model because it sure as heck doesn’t fit into this one. It is way too wide and even after sanding some off both edges it is still far from seating into place. Ultimately I cut off both lower panels, reshaped the main panel until it fits then went to paint.
       The main panel and both lower panels are done with Tamiya acrylic flat black. Once that has dried the instrument faces are filled with Testors flat white enamel. After the paint has dried I cut out some Reheat instrument face decals and placed them over the white with a healthy dose of Micro-Sol decal solvent. While this was going on I worked on getting the three main pieces of the fuselage together.
       The cockpit interior and landing gear bays were painted with Model Master interior green prior to assembly. The nose cone was oversized by about 1mm on each side. I aligned the nose gear bay and glued it into place with plenty of gap filling super-glue then sanded the piss out of it until I had a smooth seam. Once this had been accomplished I installed the main dashboard then inserted both smaller side panels with tweezers and glued them to the sidewalls of the cockpit. The inside front wall of the cockpit is not square to the kit so a small irregular gap had to be filled with CA and shaved down to meet the fuselage.
       I have test fit the wing to the main fuselage an have found it to be lacking in the general fit department to about the same degree as the nose cone had. The forward edge of the wing is about 1mm narrower than the fuselage wing stub on both the top and the bottom. It does seem to be about right once you move back into the root of the wing – oh boy, this is going to be fun! Back to the nose section; in fitting the nose section to the main fuselage once again fit problems surface. A slight lip is going to be present on either the top or the bottom of the fuselage – pick one. I decided to fit the bottom to be smooth and reshape the upper surface with sanding sticks. After several hours of sanding and close examination the seams are smooth. They may look nasty in the picture as a result of paint showing through clear glue but they are indeed smooth. During all this sanding several micro bubbles surfaced and had to be cleaned out and filled with super-glue.

2/4/04
       Now I’m going to take another look at the wings. These are solid, single piece castings and the kit instructions recommend pinning the wings to improve the joint strength. I have never done this before and the single factor that has always kept me from doing this was how to ensure that the holes for the pins would line up. A recent trip to the dentist put me on the trail of a solution. When checking the bite on a new crown he used carbon paper to make a make on the opposite side from contact. Well, carbon paper was not what I needed but after thinking it over this is the solution I arrived at:

       First I select a spot in the wing root with a good mass of resin and drill a hole (be sure to keep your drill perpendicular to the surface) then I lay some silver paint around the hole and carefully place the wing into position for just a second. In picture #1 you can see the hole with the paint in place. The paint will leave a mark on the opposite surface exactly where the corresponding hole needs to be, see picture #2. For pins I am using half inch #18 Escutcheon Pins with the heads cut off, see picture #3. These can be found at nearly any home improvement store. In this next picture you can see both pins installed in the wing root and the corresponding holes in the fuselage body. Take note of the silver residue around the holes. If the wing does not line up 100% perfect you can reinsert the drill bit and open the holes just a little more to allow the pin to wobble and allow you to line up the surfaces. When this is installed permanently super-glue will be wicked into the holes with the pins to eliminate any wobble and solidify the entire assembly.
       Now it’s time to start dealing with the large variance in the leading edge of the wing where it meets the leading edge of the fuselage. On an injection molded kit you may spend a large amount of time gluing many little pieces together, on this kit that time is consumed making the few pieces actually fit correctly.
       Looking at the pictures below, on the left arrow #4 indicates the large gap on the leading edge that will need repair. Arrow #5 on the trailing edge is another problem that is unique to this wing. The wing is cast slightly small and the trailing edge needs to be extended to match the fuselage. The other wing does not have this problem but does have the same leading edge problem. The picture below and to the right is a close up of the leading edge problem indicated by arrow #6.

2/9/04
       Over the last five days outward appearances do not show a lot of achievement however, the second wing has been pinned and attached. Once both wings had ample opportunity for the glue to cure I began to fill the huge mold mismatches at the wing roots. I would place a layer of super-glue into the joint, hit it with accelerator then sand it to conform to the correct wing shape. Three or four applications like this were needed for each wing before a smooth joining was achieved.
       The fin/rudder has some nasty warpage going on and had to be straightened out. I soaked it in hot water (180 degrees Fahrenheit) then bent it into the correct shape and held it under cold running water to lock in the shape change. This part does not fit well to the fuselage either. Lining up the trailing edge left a 1/16th inch step at the leading edge. This step had to be filled with multiple applications of super-glue and accelerator just as the wing joint had been.


Click on the images to view larger pictures

       Now I need to dig out my label tape so I can rescribe some lost panel lines under the wings. I think the worst of the fitting work has been completed now, we shall see.

2/13/04
       If you have ever needed to rescribe panel lines this trick is the thing to use. I’m using a short piece of Dymo Label tape – that’s the stuff from office supply stores used in labeling guns to make your own labels. Not only does it have a good solid structure and stick well to surfaces, it has enough depth to act as a guide for your razor knife or scribing tool. I used the existing panel lines as a guide to lay down the tape then used the sharp side of the tip of the razor knife to gently scribe the line. After having made two or three passes with the sharp edge I flipped the knife over and used the opposite side to open up the new panel line a little more so it would match the existing lines in width and depth. It takes longer to write about it than to actually do it – very easy process when you use the right tools.
       After the panel lines had been restored I packed all the openings with tissue paper dampened with water. I used a dental pick to make sure the edges were and tucked in securely. The model got wiped down with my Micro Sheen cloth and blew it off with some compressed air. I also prepared the landing gear doors and attached them to a wide piece of masking tape. I have rolled toothpicks into the edges of the tape to stiffen it and make it easier to handle under the airbrush.
       I am going to digress for a moment and talk about primers, many people ask me why I use a particular primer and if it makes a difference which color you use. Some of you already know the answers to these questions and may just want to skip ahead to the next daily update. For Alclad, which is a lacquer-based paint I use Krylon Gloss Black paint in a big 11-ounce rattle can purchased at Wal Mart. This can costs me $2.68 plus tax. It is a lacquer based paint so it will etch the plastic slightly which we call “getting a bite”. I know that many modelers use acrylic primers for Alclad but I have seen these primers react badly sometimes and destroy the paint finish. For enamels and acrylics I use Model Master gray primer cut 30% with lacquer thinner to get that “bite”.
       Now about that color question, the color of the primer will influence the look of the final paint color. That is why professional automotive painters have red primers, gray primers and white primers and will use different ones for different effects. For metallic finishes usually a white, very light gray or black primer is best. The light colors will result is a very silvery finish while the black will give a deeper ‘glow’ to the finish.
       And finally to talk about the economics of this Krylon primer, I used maybe an ounce from that rattle can which translates to about 24 cents worth of paint. A bottle of Alclad costs me around $7.00 after shipping. Now both of these paints are very thin and require multiple coats for color density. If I did not use any primer I would most likely use nearly the entire bottle of Alclad to get a good color density where as using the primer I only need about a third of the bottle for the same color density or about $2.33 worth of Alclad. Now my paint finish has cost me a total of $2.57, not bad.
       You do not want to use the Krylon paint directly from the can – you have very poor control of your paint flow with the factory nozzle. I ‘decant’ the paint first. I simply take a common drinking straw and hold one end tight to the business end of the rattle can spray nozzle and the other end into an old camera film can. Press the nozzle and collect the paint into the film can then transfer it to my airbrush where I have very good control of the paint flow. That big old rattle can will provide me with enough black paint to prime 9 or ten model airplanes at a very economical cost.
       That pretty much concludes today’s update. I’ll let this set for a few days to fully cure then shoot some Alclad onto it this weekend. Looks pretty cool all black, doesn't it?

2/17/04
       I’ve made a little more progress on this over the last few days. After the black primer had a day to cure I masked the canopy using standard masking tape. The canopy is poorly formed, the panel lines are so soft as to be almost indistinguishable and the areas that are to be clear have a rough texture to them reminiscent of Orange Peel. It appears to be on the inside and even after buffing and Future is still present. The areas that are to be painted are actually clearer than the panes that should be clear! Anyway, after masking I attached it using Testors Clear Parts cement and held it in place for a few minutes while the glue set up.
       Once the glue on the canopy had dried I decanted a little more Krylon paint and shot the canopy lightly several times. I know this means the interior framing will be black but I don’t want to jerk around with trying to lay down an enamel then sealing it to prevent a reaction with the lacquer paint – oh well. A few hours to dry and then I’ll get on with the Alclad.
       I shot the lower half with Alclad Dark Aluminum and let that cure for a few hours then came back and shot the upper surfaces, probably would have made sense to stick a large piece of dowel rod into the jet exhaust for a handle – hindsight is always 20/20. I put four or five light coats until I had a nice, solid color. I want to let this set for a few days not so the finish can get nice and hard before continuing. In the meantime I will play with a little “make your own decal” kit from Testors that I picked up at Wal Mart last weekend. You see, this kit does not come with any decals so the options are; spares box decals, painted on markings or custom made decals. The Testors kit cost five bucks so I figured it would be a good time to pick up another modeling skill – I’ll let you know how this turned out later in the construction review.

3/1/04
       While my Alclad was hardening up I loaded the software from Testors and tried my hand at some decal artwork. This is really a pretty nice little package. The software is an abbreviated version and they push you to go on-line and buy the full program for another ten bucks. I really couldn’t see the need to do that. I found I could create the images I wanted in another program, Adobe Photoshop, and copy them to this for final work. The most important item was to adjust the printer controls to reproduce the image on a high resolution rather than a regular resolution.
       I have not actually printed my decals yet but have run a couple of test prints on standard paper to verify the color density and image sizes. I’ll hold off on the final print for a few more days while I finish the model construction.
       This is not going to have a flat finish but will have a final coat of Future to give it that final shine so I can remove the canopy masks now rather than have to wait until everything is done. The tissue packing has been removed from the landing gear bays and the interior green has been touched up. The interior of the exhaust has been painted flat black then dry brushed with Gunze-Sangyo Burnt Iron. The landing gear have been painted and installed and all the gear doors have been attached. This is a clean and shiny test-bed aircraft so there is no weathering to be done. Looks like it’s time for me to print some decals and wrap this construction project up.

3/7/04
        I did my print run on the decals and have two pieces of advice for anyone using this print package, first take the sheet of decal paper and reverse roll it or press it in a large book for a few days to flatten the sheet. When I started the print the sheet jammed in my printer as a result of the curvature to the paper. Second, when the instructions say to let the ink dry give it several hours and when you apply the fixative spray use several very light coats to avoid ink runs. With that said, the decals turned out very nice and laid down with no problems. They responded just fine to Micro-Sol setting solution. The colors did seem just a little transparent, especially on the red so if I were to do these again I would try the white decal paper and trim the decals very carefully.
        The Alclad gave me a very smooth surface so I did not pre-coat with Future. After the decals were down and had dried I coated the entire model with Future floor polish to seal everything. When I started this kit I was looking for something that would be an easy, straightforward build to give myself a break from more complex projects. This was a poor choice for that end. All the main parts had fit issues, every seam required lots of work to finish, the clear parts were anything but clear, the lack of decals was annoying at best and the instructions were less that adequate. If you want to build a 1/48 DH-108 this is the only game in town so if you are going to tackle this project, roll those sleeves up and get ready for some work.






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