Although the Me 509 is often included on a list with “Luftwaffe ’46” subjects, that is truly inappropriate. Its more of a “Alt Luft ’43” subject.

As World War II was getting started, Willy Messerschmitt recognized his Bf 109 as an aging design.
Such was the pace of aircraft development at the time, that several projects were started to find a more advanced replacement.

Starting as early as 1940 Messerschmitt started plans on a new generation fighter to take advantage of the latest in airfoils, harnessing engine output, and lessons learned from combat. This first took shape as the Me 309. Approval was granted to start work on four Me 309 prototypes, but much to Messerschmitt’s frustration the project was never allocated high priority by the Air Ministry (RLM).
A cheaper, quicker to build alternate was also sought. So Messerschmitt also started work on an Me 209, that was sort of a half way point between Bf 109 and Me 309. This can be a source of some confusion, since Messerschmitt had previously built an air speed record machine in the late 1930s that was known as the Me 209. THAT machine set the airspeed record, was enshrined in the Berlin air museum, and was definitely NOT a fighter. (Press at the time claimed the Me 209 was a next gen fighter, so making a fighter under that designation preserved the fiction).

The Me 209 and Me 309 prototypes were both designed to use the Daimler-Benz DB 603 engine, which was slightly bigger and more powerful than the DB 605 used on the Bf 109G. When the prototypes were finished in 1943 the Bf 109G and Fw 190D are truly what they were competing against. Both new types were faster, especially the Me 309 that came in at 455 mph; fully 50 mph faster than the 109. The Me 209 was also faster than the Bf 109, but slower than the Fw 190D so its story ends there.
The Me 309 was enough faster to get a full flight test program, but this revealed several handling and stability problems. These likely could have been fixed, but the Me 262 was clearly the path to the future and there was no enthusiasm for further work on a piston engine fighter. When one of the prototypes suffered a nose wheel failure that totaled the airframe the program came to an end.

Which brings us to the Me 509. In concept it is the same aircraft as the Me 309 but with the engine and cockpit switching places. This offers two advantages, the first is just visibility. The pilot can see forward and below much better than on most other fighters of the era. The second advantage is it takes a lot of weight off the nose wheel. I’m not sure how deliberate this was on Messerschmitt’s part, but given that an Me 309 was lost due to nose gear failure, and many Me 262s were lost to the same issue, it seems Messerschmitt had a problem building very solid nose gear!
It does seem odd to me that no armament was intended for the nose. Admittedly its a much tighter space than in the most famous mid-engine design, the P-39 Airacobra. But a cannon through the propeller boss seems like an obvious fitting.
I’d also add that this configuration is highly speculative. It is based on engineering drawings that no metal was ever cut for. Undoubtedly there would have been changes made during construction of a prototype, and far more made to an actual production type. If the somewhat less imaginative Me 309 needed more work to be ready for production, something much more “out there” like the Me 509 would have certainly needed much more. I’m almost certain the type would have had serious stability and center-of-gravity issues.

The burning question is, could this type ever have been built? My knee jerk answer is no. But with a few qualifications. The biggest being, if the RLM had shared Messerschmitt’s enthusiasm for an improved piston engine fighter all the way back to 1940 and made adequate resources available (engineering personnel and manufacturing) some form of the fighter might have happened. It probably would have appeared in place of, or alongside the later Bf 109G series. This likely would have meant some drop in production for a very slightly better airplane. Probably not an advantageous situation for the Nazi cause.

This the Trumpeter kit. Its a simple kit but nicely molded and fits pretty well. Of course it just begs the question, why? Seriously, the Me 309 would have been far more interesting historically but they never kitted one.
The decals are Eagle Editions. The markings are for a Bf 109G-6 flown by Alfred Grislawski, an ace with 133 kills. The time is September 1943. It would have taken a truly heroic effort for Germany to have put a capable Bf 109G replacement into service at such an early date.