Registered by FAI makes sense to show the world an incontestable performance.the speed must be measured under the conditions set by the FAI. It is not a direct indication of the maximum cruising speed of the aircraft.
To give you more accurate numbers: my average cruising speed was more like 200 km/h. The difference is for wind, turning and accounting for the climb. My take-off weight was 500 kg.At this speed parasitic drag appears more clearly.
Therefore, now we best can clarify it.
I guess the speed was 185 km/h to account for the time lost in the half turn.
I also assume that the mass was 440 kg with only the pilot and 14 kg of gasoline.
In this case the drag of the rotor 8.6 x 0.2 m and 3 degrees was 420 N
I guess still the propeller thrust was 1150 N ie 100hp at 0.79 efficiency
Therefore the parasitic drag is 730 N and the parasitical drag coefficient of ArrowCopter C20 is 0.45 m2
It is only half of old Bensen without any fairing (0.9 m2) Yet the dress is nice.
The flight manual said empty weight 342 kg and fuel capacity 76 litersMy take-off weight was 500 kg.
You said 25 km/h headwind on the way. Therefore back with 25 km/h on back. This has altered than 3.5 km/h your average speed back and forth.My average cruising speed was more like 200 km/h. The difference is for wind, turning and accounting for the climb.
That is not symmetric because my best rate of climb speed is about 105 km/h and my average cruise speed is 198 km/h. I cannot go that much faster on descent as I can go slower on the climb.At last, taking in account the climb, you must also takes in account the temporary advantage of the two descents before the line.
From your text, Chris: " I emptied the left tank and about half of the right one to be as light as possible." For me this gives 14 Kg, not 35 kgWeight is higher because I carried more fuel than you assume.
If 200 km/h at weight 500 kg, ie 4900 N, then I find a parasitical drag = 0.33m2What Cd do you get with the numbers I gave you?
Computational Fluid Dynamics is very reliable when the flow is not separated from the walls. Unfortunately, on the ass of the pod the flow is largely separed.A while ago we did a state-of-the-art CFD calculation of drag at 150 km/h cruise. I must see if I can get these data. Alternatively we can do a dedicated test flight.
Seeing is believing, Alex. With this lightweight Rotax and 500 kg total weight for that flight I was able to cruise at 200 km/h.BTW, Chris (sorry, cannot resist), do you really believe that 370 kg empty weight isn't a shame for a 2-seat gyro powered by a respectively lightweight Rotax?
OK, here are the numbers hot off the press:I would be grateful