Lippisch P.13A Ramjet-Powered Interceptor Proposal
One of the most fascinating and unorthodox of all the viable German jet-powered designs was the coal-burning Lippisch P.13A delta-winged interceptor.
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Alexander Lippisch (1894-1976) became an important figure in aviation research, having earned his "wings" as an aerial photographer during World War 1 (1914-1918). Lippisch's greatest claim to fame would become the famous Messerschmitt Me 163 "Komet" rocket-powered interceptor which entered operational service with the German Luftwaffe in World War 2 (1939-1945). Throughout the war, Lippisch continued his ground-breaking work and developed some of the more fantastical of the German "paper airplane" designs - holding a strong belief in his creations to the end and delving ever-deeper into the world of delta- and flying-winged flight. Lippisch would eventually come to work for the United States in the post-war world and develop his concepts even further before passing away in Iowa at the age of 81.
The Lippisch Li P.13A was a project centered around supersonic flight through a unique airframe shape and ramjet-provided thrust. Lippisch set to work on a peculiar model that was unlike any of the war, an airframe whose general shape was akin to a diamond or triangle intended to incorporate the swept-back wing surfaces and low aspect ratio needed for supersonic travel at speeds beyond Mach 1.0. The P.13A was the embodiment of his thinking, situating the single-seat cockpit at the center of the design and as part of the frontal face of a large dorsal rudder. The fuselage was flat from a side profile and triangular from the overhead perspective, essentially a tailless "flying wing" had the dorsal rudder been removed. Wings were swept-back at an angle of 60-degrees to provide the best balance of high-speed flight and stability at those speeds. The engine would be buried in the fuselage under the cockpit floor and the installation would run with ductwork from nose to tail. The nose was a cylindrical intake port with the engine exhausting through a conventional nozzle at the base of the rudder. The fuselage would house the needed avionics and fuel stores. Developed from the outset as a technology demonstrator intending to prove the viability of several qualities (supersonic flight, excellent operational ranges through a streamlined design and low-cost operation), the P.13A surely looked to become one of the more important aviation products in history.
However, the situation heading into 1944 presented a different sort of Germany, one embroiled in a war along two fronts against multiple enemies. The Allied bombing campaign in the West was taking its toll on German infrastructure and its positions in German-held territories. In the East, the Soviet Union was amassing greater forces on a seemingly daily basis to enact thunderous offensives against battle-weary German Army troops. It would seem, from this point forward, that a defensive stand was the growing call of the day for Germany. Add to this that resources were proving scarce and talent was committed to critical projects that could be put to use immediately for the Reich, there proved little time for fanciful innovation.
With the current state of things as they were, Lippisch moved his P.13A along project under the guise of it being an interceptor project. The program suffered an early setback when the model was destroyed in an Allied air raid over Vienna. Regardless, enough of the program survived to keep the P.13A initiative alive for the interim. To power the airframe - and due to strict resources control of conventional fuels - Lippisch decided upon a coal-burning ramjet engine by Kronach to power his triangular fighter. Take-off would have been assisted by jettisonable rockets, allowing the vehicle to reach the minimum required 150mph speed before committing to the ascend. From there, Lippisch reasoned his creation could advance to 400 miles per hour as its maximum speed. Range would be 1,000 miles on one ton of coal fuel, utilizing the special airframe in conjunction with its ramjet propulsion for maximum efficiency. Tests were undertaken through a powerless research glider known as the "DM-1".