| DM-1 | |
|---|---|
 | |
| The DM-1 at Munich Prien airport after the war | |
| Role | Full-scale research glider |
| National origin | Germany |
| Manufacturer | Akaflieg Darmstadt & Akaflieg München |
| Designer | Alexander Lippisch |
| First flight | Not flown |
| Number built | 1 |
| Developed into | Lippisch P.13a |
The Lippisch DM-1 was a single-seat research glider that was designed and built in Germany from 1944. [1]
During World War II, Dr. Alexander Lippisch proposed a ramjet propelled point defence fighter, the Lippisch P.12/13a. It was a sharply-swept delta flying wing with the engine buried in a thick, blunt-nosed wing. The pilot was accommodated in the forward section of the tail fin, which was as thick as the wings and almost as large. A scale model of the P.12/13a was successfully flown at Spitzerberg, near Vienna. [2] [3]
Lippisch himself lost interest in the design and began work on the P.13b with a different wing, but he was approached by students of Akaflieg Darmstadt and Akaflieg München, who asked for vital war work so that they would not be drafted. By this time in 1944 Lippisch realised that the war was hopeless and was happy to oblige, arranging for them to build a full-scale aerodynamic test glider for the P.12/13a project. [2]
Construction was begun at the workshop of the Akaflieg Darmstadt, as the Darmstadt D-33. The workshop was bombed in September 1944, so the part-built airframe was moved to the Akaflieg München workshops at Prien am Chiemsee, where it was redesignated the DM-1 (for Darmstadt-München 1). At Prien, Wolfgang Heinemann and Hans Zacher from Darmstadt, with Klaus Metzner and Hermann Nenninger from Munich, continued the work.
The DM-1 was a single-seat glider made from steel tubing, plywood and bakelite impregnated plywood. The cockpit canopy was integrated into the fin leading edge. Launching the DM-1 was to be by piggy-back or aero-tow.
After occupation by U.S. troops in May 1945, work continued at the DM-1 on behalf of the U.S. military government, with General Patton and Charles Lindbergh visiting Prien to see the project. Completed in early November 1945, the DM-1 was shipped in a wooden box to Langley Field in Virginia where the flow behaviour of the DM-1 was examined in the NACA (National Advisory Committee for Aeronautics, forerunner of today's NASA) full-size wind tunnel.
When tested at Langley, the DM-1 was found to perform poorly. It generated significantly less lift at low speeds than small-scale models had suggested. The cause proved to be vortex lift generated by the models which, due to its much higher Reynolds number, the full-size aircraft did not produce. [4]
As a consequence it underwent a programme of modifications. Like all Lippisch deltas it had a thick wing with a blunt leading edge. A strip was fixed along the leading edge to simulate a sharp profile. This created the vortices seen on the model and greatly increased the lift. The origin of modern vortex lift theory (as seen most famously on Concorde) may thus be traced to the NACA study and the modified DM-1. [4]
The large and even thicker vertical stabilizer was removed and replaced with one of much smaller size, along with a cockpit canopy from a Lockheed P-80 Shooting Star in a more conventional position. Together with improvements to the elevon hinges, this significantly reduced overall drag. [5] [4]
After completion of testing the DM-1 was retired to the National Air and Space Museum, Smithsonian Institution in Washington, D.C. for storage at the Paul E. Garber Preservation, Restoration, and Storage Facility.[ citation needed ]
It has been suggested that the DM-1 influenced design of the Convair delta-wing jets, beginning with the XF-92A. Convair engineers are known to have examined the DM-1 and interviewed Lippisch. This has led historians to assume his technical influence, however there is no direct evidence to support this assumption. [6] On the contrary, Convair had independently discovered the thin delta wing, while the DM-1 had a thick wing and its aerodynamic behaviour is very different. They knew of Lippisch and at least one engineer met him, but his contribution was more in the nature of "moral support" than anything technical. [4]
Besides the NASA modifications, the Akafliege Darmstadt and München defined some powered designs for a development programme derived from the DM-1. [1]
Data from DM1 bis DM4 [1]
General characteristics
Performance
Related development
Aircraft of comparable role, configuration, and era
A delta wing is a wing shaped in the form of a triangle. It is named for its similarity in shape to the Greek uppercase letter delta (Δ).
The Convair XF-92 was an American, delta wing, first-generation jet prototype. Originally conceived as a point-defence interceptor, the design was later used purely for experimental purposes and only one was built. However, it led Convair to use the delta-wing on a number of designs, including the F-102 Delta Dagger, F-106 Delta Dart, B-58 Hustler, the US Navy's F2Y Sea Dart as well as the VTOL FY Pogo.
The Lippisch P.12, P.13a and P.13b were related design projects for a ramjet-powered delta wing interceptor aircraft studied in 1944 by German designer Alexander Lippisch. The P.12 and P.13a were unarmed, relying on reinforced wings to ram its opponent. The P.13a and b were to be powered by powdered coal. The DM-1 was a full-size glider, flown to test the P.12/13a low-speed aerodynamics. The design series were unrelated to the earlier P.13 produced by Messerschmitt's Lippisch design office.
The Akaflieg Stuttgart fs18a was a glider designed and built in Germany from 1938. It was characterized by a gull wing and was the first glider to have a retractable undercarriage. Only one example of the design was constructed.
The Akaflieg München Mü10 Milan is a two-seat glider aircraft that was designed in Germany in 1934. Only one copy of the design was built.
The Akaflieg München Mü22 is a single-seat research glider designed and built in Germany from 1953.
The Akaflieg München Mü26 is a high performance single-seat glider designed and built in Germany starting in 1970.
Akaflieg Darmstadt is one of approximately twenty aviation groups attached to German universities. Akaflieg is an abbreviation for Akademische Fliegergruppe, an academic group of students and faculty from a German University.
The NRC tailless glider, also called the NRL tailless glider, was a two-seat tailless research glider designed by the National Research Council of Canada and built by the National Research Laboratories, at the instigation of G.T.R. Hill who had previously designed the British Westland-Hill Pterodactyl series of tailless aircraft.
The Akaflieg Darmstadt D-6 Geheimrat, often shortened to Darmstadt D-6 Geheimrat, was an early competition glider with a single seat and high cantilever wing, designed and built by German University students in 1922.
The Akaflieg Darmstadt D-7 Margarete, often shortened to Darmstadt D-7 Margarete, was one of the earliest two seat monoplane gliders, designed and built by German university students in 1923.
The Akaflieg Darmstadt D-9 Konsul, often shortened to Darmstadt D-9 Konsul, was a high performance, single seat, cantilever monoplane sailplane, designed and built by a German University student group in 1923 for hill soaring.
The Akaflieg Darmstadt D-17 Darmstadt, also called the Darmstadt D-17 and Darmstadt I, was a high performance, single seat, cantilever monoplane sailplane, designed and built by a German University student design group in 1927. It was followed in 1928 by the Akaflieg Darmstadt D-19 Darmstadt 2, a similar aircraft with a new profile, longer span wing.
The Akaflieg Darmstadt D-28 Windspiel was a single-seat, high-performance sailplane designed in Germany in the early 1930s. Intended to exploit a growing understanding of thermal soaring, it was small and manoeuvrable, with a 12 m span; silk-covered for lightness, it weighed less (empty) than its pilots. It held the world straight-line distance record for a time in 1934.
The Akaflieg Darmstadt D-34 sailplanes were a series of experimental single seat sailplanes, designed at the University of Darmstadt in the 1950s and early 1960s to explore the structural and aerodynamic advantages of the then emerging plastics and composite materials.
The Akaflieg Darmstadt D-40 is an experimental variable geometry single seat sailplane, fitted with almost full span, camber changing flaps for optimum aerodynamics in weak thermals and integrated into the wing so as to minimise flap tip drag. One flew successfully but the D-40, like other variable geometry sailplanes, was not commercialised.
The Teichfuss Cicogna was an Italian tailless single-seat motor glider designed by Luigi Teichfuss and flown in 1936.
The RRG Fafnir, named after the legendary dragon, was a single seat German high performance glider designed by Alexander Lippisch. It won the Rhön competition in 1931 and made several outstanding flights as well as setting a fashion for gull wings.
Lore and a copy, Musterle, were high performance sailplanes designed at Darmstadt by Paul Laubenthal. Lore was flown successfully by the well known glider pilot Wolf Hirth at the 1929 Rhön (Wasserkuppe) glider competition. Musterle was used by Hirth used to demonstrate the possibilities of "blue sky" thermalling for the first time.
The Der Dessauer, later Der alte Dessauer, was a German single-seat glider built in the early 1920s. It took part in all the Rhön gliding contests on the Wasserkuppe between 1923 and 1928, flew in the Alps, and made a long-duration flight along the German sea shore.
