Question: What date did the aircraft fly four times that had a power to weight ratio of 33 W/kg / 50 lb/hp ?

text: Power-to-weight ratio
Examples -- Vehicles
Most vehicles are designed to meet passenger comfort and cargo carrying requirements . Different designs trade off power-to-weight ratio to increase comfort , cargo space , fuel economy , emissions control , energy security and endurance . Reduced drag and lower rolling resistance in a vehicle design can facilitate increased cargo space without increase in the ( zero cargo ) power-to-weight ratio . This increases the role flexibility of the vehicle . Energy security considerations can trade off power ( typically decreased ) and weight ( typically increased ) , and therefore power-to-weight ratio , for fuel flexibility or drive-train hybridisation . Some utility and practical vehicle variants such as hot hatches and sports-utility vehicles reconfigure power ( typically increased ) and weight to provide the perception of sports car like performance or for other psychological benefit . A locomotive generally must be very heavy in order to develop enough adhesion on the rails to start a train . As the coefficient of friction between steel wheels and rails seldom exceeds 0.25 in most cases , improving a locomotive 's power-to-weight ratio is often counterproductive . However , the choice of power transmission system , such as variable-frequency drive versus direct current drive , may support a higher power-to-weight ratio by better managing propulsion power . Notable low ratio [ edit ]
Power-to-weight ratio (or specific power or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power source. It is also used as a measurement of performance of a vehicle as a whole, with the engine's power output being divided by the weight (or mass) of the vehicle, to give a metric that is independent of the vehicle's size. Power-to-weight is often quoted by manufacturers at the peak value, but the actual value may vary in use and variations will affect performance. The inverse of power-to-weight, weight-to-power ratio (power loading) is a calculation commonly applied to aircraft, cars, and vehicles in general, to enable the comparison of one vehicle's performance to another. Power-to-weight ratio is equal to thrust per unit mass multiplied by the velocity of any vehicle.
Vehicle Power Vehicle Weight Power to Weight ratio
Benz Patent Motorwagen 954 cc 1886 560 W / 0.75 bhp 265 kg / 584 lb 2.1 W/kg / 779 lb/hp
Stephenson 's Rocket 0-2-2 steam locomotive with tender 1829 15 kW / 20 bhp 4,320 kg / 9524 lb 3.5 W/kg / 476 lb/hp
CBQ Zephyr streamliner diesel locomotive with railcars 1934 492 kW / 660 bhp 94 t / 208,000 lb 5.21 W/kg / 315 lb/hp
Alberto Contador 's Verbier climb 2009 Tour de France on Specialized bike 420 W / 0.56 bhp 62 kg / 137 lb 6.7 W/kg / 245 lb/hp
Force Motors Minidor Diesel 499 cc auto rickshaw 6.6 kW / 8.8 bhp 700 kg / 1543 lb 9 W/kg / 175 lb/hp
PRR Q2 4-4-6-4 steam locomotive with tender 1944 5,956 kW / 7,987 bhp 475.9 t / 1,049,100 lb 12.5 W/kg / 131 lb/hp
Mercedes-Benz Citaro O530BZ H 2 fuel cell bus 2002 205 kW / 275 bhp 14,500 kg / 32,000 lb 14.1 W/kg / 116 lb/hp
TGV BR Class 373 high-speed Eurostar Trainset 1993 12,240 kW / 16,414 bhp 816 t / 1,798,972 lb 15 W/kg / 110 lb/hp
General Dynamics M1 Abrams Main battle tank 1980 1,119 kW / 1500 bhp 55.7 t / 122,800 lb 20.1 W/kg / 81.9 lb/hp
BR Class 43 high-speed diesel electric locomotive 1975 1,678 kW / 2,250 bhp 70.25 t / 154,875 lb 23.9 W/kg / 69 lb/hp
GE AC6000CW diesel electric locomotive 1996 4,660 kW / 6,250 bhp 192 t / 423,000 lb 24.3 W/kg / 68 lb/hp
BR Class 55 Napier Deltic diesel electric locomotive 1961 2,460 kW / 3,300 bhp 101 t / 222,667 lb 24.4 W/kg / 68 lb/hp
International CXT 2004 164 kW / 220 bhp 6,577 kg / 14500 lb 25 W/kg / 66 lb/hp
Ford Model T 2.9 L flex-fuel 1908 15 kW / 20 bhp 540 kg / 1,200 lb 28 W/kg / 60 lb/hp
TH ! NK City 2008 30 kW / 40 bhp 1038 kg / 2,288 lb 28.9 W/kg / 56.9 lb/hp
Messerschmitt KR200 Kabinenroller 191 cc 1955 6 kW / 8.2 bhp 230 kg / 506 lb 30 W/kg / 50 lb/hp
Wright Flyer 1903 9 kW / 12 bhp 274 kg / 605 lb 33 W/kg / 50 lb/hp
Tata Nano 624 cc 2008 26 kW / 35 bhp 635 kg / 1,400 lb 41.0 W/kg / 40 lb/hp
Bombardier JetTrain high-speed gas turbine-electric locomotive 2000 3,750 kW / 5,029 bhp 90,750 kg / 200,000 lb 41.2 W/kg / 39.8 lb/hp
Suzuki MightyBoy 543 cc 1988 23 kW / 31 bhp 550 kg / 1,213 lb 42 W/kg / 39 lb/hp