CMR 1/72 Supermarine Type 300

Supermarine's Chief Designer, R.J. Mitchell, had won four Schneider Trophy seaplane races with his designs: (Sea Lion II in 1922, S 5 in 1927, S 6 in 1929 and S 6b in 1931), combining powerful Napier Lion and Rolls-Royce "R" engines with minute attention to streamlining. These same qualities are equally useful for a fighter design, and, in 1931, Mitchell produced such a plane in response to an Air Ministry specification (F7/30) for a new and modern monoplane fighter.

This first attempt at a fighter resulted in an open-cockpit monoplane with gull-wings and a large fixed, spatted undercarriage. The Supermarine Type 224 did not live up to expectations; nor did any of the competing designs, which were also deemed failures.

Mitchell immediately turned his attention to an improved design as a private venture, with the backing of Supermarine's owner, Vickers. The new design added gear retraction, an enclosed cockpit, oxygen gear and the much more powerful newly developed Rolls-Royce PV-12 engine, later named the Merlin.

By 1935, the Air Ministry had seen enough advances in the industry to try the monoplane design again. They eventually rejected the new Supermarine design on the grounds that it did not carry the required eight-gun armament, and did not appear to have room to do so.

Once again, Mitchell was able to solve the problem. It has been suggested that by looking at various Heinkel planes, he settled on the use of an elliptical planform, which had much more chord to allow for the required eight guns, while still having the low drag of the earlier, simpler wing design. Mitchell's aerodynamicist, Beverley Shenstone, however, has pointed out that Mitchell's wing was not directly copied from the Heinkel He 70, as some have claimed; the Spitfire wing was much thinner and had a completely different section. In any event, the elliptical wing was enough to sell the Air Ministry on this new Type 300, which they funded by a new specification, F.10/35, drawn up around the Spitfire.

The elliptical wing was chosen for superior aerodynamic attributes but it was a complex wing to construct and the Messerschmitt Bf 109's angular and easy-to-construct wing offered similar performance (model per model) to the Spitfire. It has been reported that the Bf 109 took one-third the man hours to construct compared to the Spitfire.

One flaw in the thin-wing design of the Spitfire manifested itself when the plane was brought up to very high speeds. When the pilot attempted to roll the plane at these speeds, the aerodynamic forces subjected upon the ailerons were enough to twist the entire wingtip in the direction opposite of the aileron deflection (much like how an aileron trim tab will deflect the aileron itself). This so-called aileron reversal resulted in the Spitfire rolling in the opposite direction of the pilot's intention.

The prototype (K5054) first flew on 5 March 1936, from Eastleigh Aerodrome (later Southampton Airport). Testing continued until 26 May 1936, when Mutt Summers, (Chief Test Pilot for Vickers (Aviation) Ltd.) flew K5054 to Martlesham and handed the aircraft over to Squadron Leader Anderson of the Aeroplane & Armament Experimental Establishment (A&AEE).

The Air Ministry placed an order for 310 of the aircraft on 3rd June 1936, before any formal report had been issued by the A&AEE, interim reports being issued on a piecemeal basis.

A feature of the final Spitfire design that has often been singled out by pilots is its washout feature, which was unusual at the time. The incidence of the wing is +2° at its root and −½° at its tip. This twist means that the wing roots will stall before the tips, reducing the potentially dangerous rolling moment in the stall known as a spin. Many pilots have benefited from this feature in combat when doing tight turns close to the aircraft's limits, because when the wing root stalled it made the control column shake, giving the pilot a warning that he was about to reach the limit of the aircraft's performance.

Naturally, it all starts with cleaning up the bits that one is going to use. This means the fuselage halves, wing and interior bits. The interior builds up well as there are only 6 parts; two bulkheads, a centerline trough, a seat, control stick and rudder pedals. I left some of the resin sprue stub on the underside of the seat and used that to attach it in place. You can't tell it is like that from the outside. All the bits were painted RAF Interior Green except for the seat which was Aluminum. Control column top and instrument panel were done in black. It would have been great to have a set of etched belts and instrument panel in with the kit as they would have added quite a bit. There is sidewall detail in terms of stringers and some black boxes that were painted up. Not a lot of detail, but enough for a bare bones plane like the Spit prototype.

Then I glued the forward part of the fuselage together. The fuselage halves are a bit warped due to being so thin, but by gluing in stages, that will all go away. I then glued a portion of the upper fuselage behind the cockpit. When that had dried, I installed the cockpit from the underside and then continued to glue the fuselage halves in steps working to the rear. This allowed me to keep things aligned during the glue.

The wings have some air pockets to fill where it attached to the pour stub. This took several applications of Mr. Surfacer 500. During this, I test fit the wing to the fuselage. I hate to say it, but the wing is broader than the root area on the fuselage. It seems that the best way to tackle this is to remove material from the lower front cowling and fill in the overhang on the upper wing root. This is because the rear fits very well and were I to trim the back of the wing, I'd have a larger mismatched area on the long sweep of the wing filet.

Well, I found out that the reason for some of the over/undersize parts is that the RTV molds used are prone to temperature/humidity changes and so they expand and shrink, sometimes quite a bit. I had not known this facet and it does explain things. Even more reason why some of these kits are recommended for experienced builders. Anyway, I removed the area marked in blue in the image above and sanded down the forward wing root area a tad on the fuselage to get a good fit. The usual filler was needed to take care of the gaps once I glued the wing in place. I left the rear section uncemented for the time being as I found that I'd somehow glued the tail in such a manner as it was not straight. This wasn't apparent until I glued on the wing.

Fixing this took about 30 seconds after I heated up the water in a kettle to near boiling. Pouring the hot water over the tail allowed me to move it into position and dousing it in cold tap water fixed it in place. Easy and the best way to fix bent resin.  I then proceeded to glue the rear wing. After the usual filler, the tail planes were attached. These are keyed (assuming you don't cut off the keys) so you won't get them installed upside down. I then started on trimming the vac canopy.

Folks, I really don't like vac canopies as I have trouble getting them to fit and often have trouble masking them properly. This one was no different and I'm glad a spare was included as I used it. The canopy was then attached to the fuselage using white glue. I then used Mr. Surfacer to fill in the gaps (which were many).

The oil cooler and radiator were glued to the underside of the wings and gaps were handled with a couple of Mr Surfacer applications. The rudder was then glued on and it was a bit oversize as you can see. This was sanded down without any problem. With the airframe complete, it was time for paint.

I first gave the airframe a coat of primer to help spot any areas that I missed. Lucked out this time and used a fresh bottle of Alclad II primer. Unlike the earlier bottle, this went on smoothly without any of the roughness I experienced before. I then painted the flight control surfaces with Alcald II Aluminum. When dry, these were masked off. The nose was painted with Polished Aluminum, though it may end up getting the Bare Metal Foil treatment if it doesn't seem shiny enough. This was also masked off.

The color of the airframe is described as being a yellow green zinc chromate. The box art looks almost light grey with a tinge of yellow while other artwork I've seen tends toward a more yellow color. Since there are no color photos, I decided to mix up my own color on this and ended up with a yellow green shade that seems about right to me. You may think it too intense a color and perhaps it is, but it is what I'm going with. This was sprayed over the entire airframe and later the trim tabs were brush painted with this shade.  I also painted the prop this color, leaving the spinner in aluminum. I did this because on the drawings that came with the kit, this was shown as the same shade as the rest of the plane. There is a nose panel that is 'red primer'. I used a reddish brown paint I had mixed up for this area. When dry, the airframe was given a coat of gloss acrylic clear (Future).

Next the landing gear, which had been painted aluminum and had the oleos wrapped with Chrome Bare Metal Foil, were glued in place. The hole for the tail skid was opened up and this part installed. Then the main wheels were attached with the top of them leaning outboard as shown in the instructions.

Then it was time to do something about the decals. These took a bit to slide off the backing when using cold water. They stuck well but were unresponsive to Microscale's setting solution, resulting in some silvering. I then applied some Solvaset to see if that would help. Help it did so I suggest using something a tad strong on these. The next thing I did was to brush paint on a matte clear. Yep, brush paint. Vallejo's matte clear goes on superbly and I had no problems with it. I basically did this as I'd stupidly removed the masking from the cowling and canopy and didn't want to put it all back on just to spray on the clear matte.

The last steps were quite simple. The wing had holes drilled in the leading edge for the two pitot tubes. These were glued in place, as was the prop. That was basically it. As the engine had not been run that much, I left off any exhaust staining, nor did I do oil flow stains from the oil cooler.

This is a very nice kit and a must for those who are really into Spitfires. I wholeheartedly agree with the commentary on the box that this kit is for experienced builders as there were some areas that needed more than just gluing and filler. However, it isn't beyond the realm of most of you and even a beginner into resin kits can do a good job as long as they take their time and think things through. I'm sure my choice of colors will bring some commentary and that is fine. It is my interpretation of things and since there are no color photos of the prototype, then as long as one chooses something reasonable, then that should work fine.