Nimbus 3 DM engine fades at 40-50 m AGL, wingtip strike on emergency turn

On a self-launch from Dahlemer Binz, the pilot of a Nimbus 3 DM was seriously injured and the aircraft destroyed. The first takeoff had been aborted with low engine power suspected of vapor lock; a follow-up ground run was normal. On the second attempt the climb was normal to about 40-50 m AGL when engine power dropped again. With forest east of the field the pilot turned left near the RWY 23 threshold toward the glider area; the left wingtip touched in the turn, the aircraft rotated left, and the fuselage buckled as it slid about 87 m sideways.

1. Self-launch attempt at Dahlemer Binz: Schempp-Hirth Nimbus 3 DM (1991 build, SN 18, two-seat motorglider with Solo 2625-2 engine and BM-G1-160-R-120-1 propeller, retractable). 6,265 h total / 1,359 landings; total payload on the flight ~165 kg (within limits). Pilot 46 yo, EU SPL with TMG + Sailplane + Powered Sailplane and Winch/Aero Tow/COM-OPS endorsements; 994 h total, 350 h / 85 starts on type, 60 h / 13 starts in last 90 days; medical class 2 valid. Person on rear seat held SPL with instructor rating, formally on board as passenger. Weather: VMC, visibility >10 km, cloudless, E wind 8 kt, ~24 °C.
2. First takeoff aborted, low engine power: BFU 'additional information': a first takeoff attempt was aborted earlier because of insufficient engine power. The pilot suspected vapor lock (Dampfblasenbildung) as the cause. A subsequent ground run was carried out and the engine functioned normally — the pilot then attempted the takeoff again.
3. Forest to east, no outlanding option: The airfield at Dahlemer Binz (EDKV, 1,896 ft AMSL, 1,070×30 m asphalt rwy 053°/233°; with parallel grass winch strip and 700 m glider landing strip) is framed to the north and east by dense forest. East of the field there were no suitable outlanding options.
4. Engine power drops at ~40-50 m AGL: On the second takeoff attempt the takeoff roll and initial climb on RWY 05 were unremarkable per crew + ground witnesses. At 40-50 m above ground the engine power decreased such that further climb was no longer possible.
5. Left turn toward glider area: Given the forest to the east, the pilot decided to perform an emergency landing on the airfield grounds. Near the threshold marking of RWY 23 (opposite end of the asphalt), the pilot turned left toward the glider operations area to set up the landing.
6. Left wingtip strikes ground in turn: During the left turn toward the glider area, the left wingtip touched the ground, which rotated the aircraft further to the left.
7. Fuselage buckled, slides 87 m sideways: The rear fuselage tube bent in front of the empennage; the aircraft then slid approximately 87 m sideways across the glider operations area on heading 350°, leaving a straight slide mark. Final resting position 5.6 m southwest of a glider launch winch, longitudinal axis pointing 232°.
8. Aircraft destroyed near winch: Cockpit destroyed back to the seat-back; rear fuselage tube buckled; left wingtip cap ~0.70 m delaminated, aileron and flap torn off; right wing damaged at wingtip cap and aileron; nose with scratches and dents. Airbrakes retracted. Pilot seriously injured. Post-accident engine examination showed no anomalies. Wreckage analysis did not identify technical defects. BFU concluded the investigation as a facts-only summary report (per § 18 FlUUG); no analysis or conclusions.