The pilot attempted a short field takeoff from a grass airstrip at the time of the accident. During the airplane’s takeoff roll, the passenger, who was seated in the left pilot seat, said that the windsock was “inconsistent.” At an airplane speed of 45-50 mph, the pilot applied control back pressure to ease the airplane into ground effect. The airplane became airborne but quickly settled back onto the runway and became airborne again. The airplane airspeed did not increase and remained at 40 mph. The pilot asked the passenger to continue to read the airspeed indications as the pilot realized that they were running out of remaining runway. The pilot reduced some of the control back pressure and pushed the airplane nose down out of fear of an aerodynamic stall and in hopes of increasing airspeed. The airplane descended and impacted the ground about 100 yds south of the departure runway and nosed over. The airplane sustained substantial damage that included damage to the right wing, aileron, and empennage. The pilot stated there was no mechanical malfunction or failure of the airplane that would have precluded normal operations. Recorded weather observations, north and northeast and 15-16 nm from the airport, indicated a quartering tailwind relative to the runway direction prevailed at the time of the accident.