The "parasite" fighter had long held an interest within the minds of aircraft engineers, particularly as new methods of propulsion were being investigated and formally tested. The concept of the parasite fighter was simple enough in theory, but - time and again - proved near impossible in practice. The general idea behind it was to supply those lumbering bomber formations with a capable fighter design by allowing these bombers to "carry" their own fighter defense wherever they went. Once enemy fighters were spotted, the parasite fighters would be unleashed from their host aircraft to engage the enemy. From there, the parasite fighter could either be recovered by the host aircraft (using some elaborate and often times dangerous retrieval scheme) or the fighter pilot could simply bail out of his aircraft over friendly territory, ready to be picked up by friendlies. The Messerschmitt 328 was intended as such a parasite contraption and was envisioned as part of the inherent defense system of the optimistic German "super bombers" being planned. However, the smallish Me 328 languished through an unexpectedly long development period that ultimately saw itself produced in a few workable prototypes. Early forms were engine-less gliders while later forms were trialled with "pulse jet" engines. A third design even fitted a single turbojet engine. Needless to say, the Me 328 failed to materialized into any serious production form prior to the end of the war, this mostly being due to the insufficient mix of airframe with the aforementioned pulse jet engines. Despite the projects cancellation, the Me 328 was seriously considered to fulfill an array of roles being considered by German High Command - it being thought as a good candidate to fulfill a larger body of roles other than that of parasite fighter.
The Me 328 began as project "P.1073" for the Messerschmitt firm sometime in 1941. Messerschmitt had solidified its name in the war up to this point thanks to their excellent Messerschmitt BF 109 fighter design - a single-seat, single-engine airframe that gave even the spectacular Supermarine Spitfire and North American P-51 Mustang a run for their money. The BF 109 went on to become one of the most produced fighters of the war. Messerschmitt was also responsible for the design and ultimately production of what is hailed as the world's first jet-powered fighter in the Me 262 "Schwalbe". Like many of the other well-known German aviation firms during the war, Messerschmitt did not shy away from expanding its horizon when it came to new aircraft designs that would be powered in a myriad of ways.
In her original guise, the P.1073 was to fulfill the role of bomber escort. German bombers would have had to fit some modifications to their airframe to make this happen, either launching their parasite fighter defense by tow lines or launch rails. To keep production costs down, the design was to be constructed of wood wherever possible, a practice still common throughout World War 2 despite the heavy use of metal-skinned aircraft. Three major base forms were conceived with the first expected to be a powerless glider. The second was to feature a pair of pulsejet engines for its propulsion. The third design was of particular note in its intended use of a Junkers Jumo 004 series turbojet engine.
The Me P.1073 project was delivered for further research to the German Research Institute for Sailplane Flight to which two competent variants ultimately arose - the Messerschmitt fighter-minded "Me 328A" and the bomber-minded "Me 328B" - this by 1942. Since the idea was to provide the Luftwaffe with a cost-effective solution, the Me 328 airframe would be only slightly modified between the two forms and the designw as small enough to still be considered for the parasite fighter role. It was estimated that the production of one Me 328 would come in at only a fraction of what it cost to produce just one of the two main German fighters of the time - the BF 109 and Focke-Wulf Fw 190.
Two workable prototype glider aircraft were completed and tested at altitudes between 10,000 and 20,000 feet, this accomplished using a Dornier Do 217 series twin-engine, medium bomber. Additional testing included fitting the airframe with rockets for ground-based self-launching under its own power and not having to rely on a host aircraft to get aloft. Progress was deemed promising and seven more prototypes - these fitted with 2 x Argus As 014 series pulsejet engines each - soon joined the original prototype pair. Several static tests ensued with these pulsejet-powered airframes but excessive vibration soon grounded the lot. Vibrations were a cause of concern and generally put the pilot at risk of losing control of his mount or having his aircraft fall apart altogether. This effect was also noted in the development of the V-1 rocket which used the same propulsion method. The vibration issue was never fully solved for the Me 328 and the program was more or less ended by the middle of 1944. The proposed 2 x 20mm MG 151/20 cannon armament was never fitted.
Despite the project's "no-go", work still progressed to a limited extent. A four-engine, pulsejet-powered bomber variant was brainstormed but, like the parasite fighter before it, never realized. Like most other outlandish super weapon ideas, Adolf Hitler himself endorsed the Messerschmitt project but much stood in the way of realization for the diminutive Me 328. War materials and manpower were of short supply as Germany now fought a defensive war along multiple fronts and not everyone in power shared Hitler's enthusiasm on such schemes, believing resources could be best served elsewhere.
The Me 328 was later conceived for role such as that of a navalized fighter being launched by a U-Boat submarine. In a ground-launched form, the Me 328 would have been a cheap point defense interceptor to be used in much the same way as the rocket-powered Me 163 "Komet". The Me 328 was also to have fulfilled the role of ground attack fighter. Alas, as with the previously defined roles, all these visions proved equally fruitless.
In her completed forms, the Me 328 took the appearance of a conventional aircraft design. She was smaller in size when compared to the jet-powered Heinkel He 162 "Volksjager" ("People's Fighter"). The He 162 was built in some number by the end of the war and intended to defend Germany proper to the last man, built along the cheap and expected to be flown by German youth with little training. Likewise, the Me 328 was a relatively simple little beast with a stubby forward nose cone followed by a multi-piece canopy with framing. The aircraft was to be crewed by a single personnel and controls would have most likely been rudimentary. A raised "spine" along the fuselage top made views to the rear rather poor but other views could generally be considered good. There was a short empennage featuring a rounded vertical tailfin with smallish horizontal planes offset to either fin side. The vertical tail fin sported sweep only along the leading edge. The base of the empennage swept upwards towards the tail fin. The main wing assemblies were high-mounted affairs fitted to either side of the cockpit walls. There was some sweep on both the leading and trailing edges giving a tapered look. Each wing sported dihedral (upward angle) away from the fuselage. The pulsejet engines were underslung along each wing, extended out passed the wing trailing edges. These engines were relatively featureless, sporting a bulbous forward compartment and a smooth tubular rear housing.
The Me 328 measured in at 27 feet, 7 inches in length with a 20 foot, 6 inch wingspan. She measured 7 feet in height. Weights were listed at 4,056lbs empty and 5,896lbs when fully loaded. Power was to be supplied from a pair of Argus As 014 series pulsejets delivering up to 1,320lbf of total thrust. Maximum speed would have topped 375 miles per hour with a service ceiling of 30,500 feet - certainly on par with Allied fighters of the time. Range was restricted to just 352 miles but that was negligible considering the nature of the aircraft.
As a finale stroke, the Me 328 was once again envisioned to fulfill yet another role - this time that of a manned flying bomb. In this macabre role, the German pilot would be ferrying a 2,000lb warhead to the designated target and drive his entire aircraft - payload and all - into said target. In its original form, the design was to be based on the ill-fated Me 328B proposed bomber model. The paper design was refined with a Junkers Jumo 004 series turbojet engine to become the Me 328C. As can be surmised, even the promising jet-powered Me 328C was not to be. The manned flying bomb project did progress, however, with the focus falling to the Fieseler Fi 103R ("Reichenberg") design - a manned version of the V-1 terror weapon. These were to be used by the suicidal "Leonidas" Squadron (ala the Japanese "kamikaze"). The Leonidas Squadron operated from April 17th to April 20th in 1945 with some thirty-five German pilots committing suicide for the Fatherland against Russian foes at the Oder River. Little impact (other than psychological) of these efforts was noted.
Like many of the German wonder projects of World War 2, the Me 328 went down as a footnote in Luftwaffe lore. The pulse engine technology as it stood was never fully capable for the particular Me 328 airframe. As before - and well after - the parasite concept proved too complicated to ever become a serious battlefield component and Germany's war machine was slowly grounded to a halt from all angles until its eventual capitulation in May of 1945.