| DM-1 | |
|---|---|
 The DM-1 at Munich Prien airport after the war | |
| General information | |
| Type | Full-scaleresearch glider |
| National origin | Germany |
| Manufacturer | Akaflieg Darmstadt &Akaflieg München |
| Designer | |
| Number built | 1 |
| History | |
| First flight | Not flown |
| Developed into | Lippisch P.13a |
TheLippisch DM-1 is a single-seatresearch glider that was designed and built in Germany from 1944.[1]
DuringWorld War II,Dr. Alexander Lippisch proposed aramjet propelled point defense fighter, theLippisch P.12/13a. It was a sharply-swept deltaflying 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 theP.13b with a different wing, but he was approached by students ofAkaflieg Darmstadt andAkaflieg 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 theAkaflieg Darmstadt, as the Darmstadt D-33. The workshop wasbombed in September 1944, so the part-built airframe was moved to theAkaflieg München workshops atPrien am Chiemsee, where it was redesignated the DM-1 (for Darmstadt-München 1). At Prien,Wolfgang Heinemann and Hans Zacher from Darmstadt, withKlaus Metzner andHermann 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, withGeneral Patton andCharles Lindbergh visiting Prien to see the project. Completed in early November 1945, the DM-1 was shipped in a wooden box toLangley Field inVirginia where the flow behaviour of the DM-1 was examined in theNACA (National Advisory Committee for Aeronautics, forerunner of today'sNASA) 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 higherReynolds 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 modernvortex lift theory (as seen most famously onConcorde) 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 aLockheed P-80 Shooting Star in a more conventional position. Together with improvements to theelevon hinges, this significantly reduced overall drag.[5][4]
After completion of testing the DM-1 was retired to theNational Air and Space Museum,Smithsonian Institution inWashington, D.C. for storage at thePaul E. Garber Preservation, Restoration, and Storage Facility.[citation needed]
It has been suggested that the DM-1 influenced design of theConvair delta-wing jets, beginning with theXF-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
