Scorpion MK2 assembly day 9: flight test.
Here is my report after the test flight period.
A previously explained, I went through a complete routine of system tests with the Scorpion before doing the test flight.
The first round consisted of ground range tests with the engine OFF then with the engine running. Once I was satisfied with the performance of the Weatronic system, I went for a taxi test.
I started with the brakes system power reduced to 70% and did some high speed rejected takeoffs. Ended up reducing the brakes power to 50% to avoid locking the wheels.
All the other controls performed as expected during this test, so I went ahead for a first flight.
The program of the first flight was as followed:
takeoff, climb with gear down and takeoff flap setting, stall, recovery from stall, second pass at high altitude with landing flaps, stall, recovery from stall, descend to circuit altitude, trimming, one touch and go and flap retraction to takeoff flaps, one full stop landing with landing flaps.
The stall speeds from this first test flight were: Vsf15= 62 kph,
The readout of the stall speed at flaps 15: 47 km/h + 15 kts head winds.
Vsf30= 54 kph.
The readout of the stall test flaps 30. 44 km/h + 10 km/h of head winds.
This enabled me to set the approach speed at 1.3Vs as followed: 70 km/h
This is the speed that I have entered as min speed in the Weatronic voice system as min warning.
Top speed test was done later on flight 5 with several passes head wind and down wind. The average of two consecutive passes gave me 248 km/h or 154 mph.
Here is the data readout of these two passes:
Down wind pass at 262 km/h:
Next head wind pass at 234 km/h
The Merlin VT-80 does a perfect job on this airframe by keeping it light and efficient. Don't forget that the VT-80 features the best power-to-weight-to-price ratio of the market and is incredibly reliable and extremely well built. The engine specific consumption is so low that I recommend using our 2.2 l kevlar tank.
This saves another 2 lbs at takeoff weight.
I have done all the Test flights in Dubai by 110 F temperature and with a pressure of 995 Hpa. This gives an density altitude of about 4000 ft and the thrust available is 70N/ 14 lbs in these conditions.
However, takeoff occurs within 50 meters with flaps 15. Aerobatics capability and performance is excellent with this combo.
The plane is very easy to land as one can see on the numerous videos I posted recently.
Overall it is a great looking airframe, featuring a manufacturing quality among the best in the world, very easy to fly and able to perform most aerobatics maneuvers, including snap rolls. The VT-80 combo is fantastic, giving a very light weight and making the plane very easy to setup and maintain.