|A model of the RMI-8|
The final result of a development project (1943-1945) running under the codename X/V. The fast fighter was designed by Vilmos Marton, Dezső Marton and László Varga as a high-speed, heavily armed replacement for both the Bf 109G and the Me 210Ca, two aircraft then being produced under licence in Hungary by Rába and MÁVAG from 1943 onwards. This RMI-8 project was the peak of Hungarian aircraft development during World War II.
Design and development
RMI-8 was designed to be a pure interceptor in order to defend Hungary from terror-bombings. This demanding role needed a very capable fighter that could fight against the numerical superiority of Allied and Soviet fighters (manoeuvring dogfight) while able to protect the cities from bombers (high-speed striking) simultaneously.
In order to attack the Allied and Soviet bomber groups accompanied by numerous fighters the designers planned a relatively small, fast airplane using the best existing elements of types produced in Hungary (mainly the Bf 109 G-6 version). Hungary had no engine powerful enough by the standards of 1944, thus they chose to use two Daimler-Benz DB 605A-1 in a push-pull configuration in order to minimize drag. Unlike the German Do 335 the propeller was not driven by shaft, it was directly behind the engine, so the control surfaces were carried by twin booms, as on the SAAB 21 or de Havilland Vampire.
With two engines the RMI-8 would have been able to achieve a fairly high speed; according to theoretical calculations 800 km/h vmax would have been possible even without MW 50 boost in clean level flight. This aircraft was a pure interceptor (maneuvering aerial combat), thus it was designed to be relatively small in size (only 15% bigger than a Bf 109G-6) in order to achieve as good manoeuvrability as possible. X/V carried a relatively small amount of fuel and weaponry, which means two 8 or 13 mm machine guns (cowling) and two 30 mm autocannons (wing/boom hubs), and not more than 500 kg external load. As the type was not designed for bombing, only drop tanks would have been carried in practice.
Due to the rear propeller, the pilot could not leave the airplane in a conventional manner, so a spring-driven catapult was designed for the prototype. The rear engine also functioned as "armor", because it would have provided some protection for the pilot and the first engine, so the survival of the type could have been quite high despite the lack of real armor (RMI-8 could fly with a single working DB 605 like a Bf 109).
The prototype (XV+01 callsign) was destroyed during a bombing raid on April 13, 1944 before its maiden flight; due to the deteriorating war situation there was no possibility to build a second prototype.
Data from A Magyar Királyi Honvédség fegyverzete 
- Crew: 1
- Length: 10.2 m (33 ft 6 in)
- Wingspan: 11.8 m (38 ft 9 in)
- Height: 3.5 m (11 ft 6 in)
- Gross weight: 4,000 kg (8,818 lb)
- Powerplant: 2 × Daimler-Benz DB 605A-1 V-12 inverted liquid-cooled piston engines 1,475 PS (1,454.82 hp; 1,084.86 kW)
- Maximum speed: 800 km/h (500 mph, 430 kn)
- Ferry range: 1,000 km (620 mi, 540 nmi) with drop tank
- Service ceiling: 11,500 m (37,700 ft)
- 2 × 30 mm (1.18 in) MK 103 cannon (in wing)
- 2 × 13 mm (0.51 in) MG 131 machine gun or 2x 8 mm (0.315 in) Gebauer machine guns, cowl-mount and synchronized.
- 1x drop tank (normally RMI-8 would not have carried any external load, because speed and maneuverability were priority)
- "Marton X/V". airwar.ru.
- "Dr. Hegedűs, Ernő - Ozsváth, Sándor: Többfeladatú harci repülőgépek rendszeresítésének hatása a német és magyar repülőipari kapacitások kihasználtságára a második világháborúban" (PDF). Katonai Logisztika. 21/II.: 149-177. 2013.
- Bonhardt, Attila - Sárhidai, Gyula - Winkler, László: A Magyar Királyi Honvédség fegyverzete. Budapest, hungary: Zrínyi. 1992. ISBN 963-327-182-7.
- "Marton X/V". ru-wunderluft.livejournal.com/.
- "RS Models 1/72 Marton X/V Heavy Fighter". internetmodeler.
- "RMI-8 X/V". Balaton Modell.