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Thursday, November 27, 2014

Flying the Rotmilan Midi

Read also:
Part 1: Kit overview
Part 2: Assembly

After testing many many F3F sailplanes over the last 20 years, I can say that I can split them in 2 main families: the "Slippy" and the "Grippy". The Slippy includes planes having a fast natural speed, even with low ballast. The grippy are  planes providing lots of lift in the turn and that can carry lots of ballast, and most of the time need a minimum weight to fly fast. The Rotmilan is part of the Slippy family, that is to say using a section which is more naturaly fast.

In small condition, the Rotmilan is fine but cannot do tight turns with low lift. It starts to breath in medium condition and is an easy and well mannered plane. In stonger condition, it doesn't need too much ballast, and can manage the crossed wind good.  The Rotmilan is also doing excellent bank and yank turns, very aggressively, where some other place doesn't like it. Energy management turns or half roll half loop turn are also possible. The turn technique will of course give different result depending of the slope, the edge, the wind speed, etc ...

In medium to strong condition, as soon as it reach it's flight regime, the Rotmilan retains its energy very well, and can bank and yank hardly with an excellent exit speed. HN sections are know to be optimized without the extensive use of flap to change the camber. Therefore the amount of snapflap must be low otherwise the plane slow down in turn. I found a good compromise with a CoG at 106mm.

Compared to his larger brother the standard Rotmilan, the Rotmilan Midi is more agile and can be flown more aggressively. I also found that it turns better with a bit more grip, thanks to the equivalent tail for a shorter wingspan and shorter fuselage.

My Settings
  • CoG: 106 mm from the leading edge
  • Elevator: 6 mm Up / 6mm Down
  • Rudder: 10 mm Up / 10 mm Down
  • Ailerons (measured at the intersection between flaps and ailerons)
- Ailerons: 30 mm Up / 15mm Down
        - Flaps: 15 mm Up / 5mm Down
  • Snapflaps(measured at the intersection between flaps and ailerons)
- Ailerons: 6mm Down
        - Flaps: Aligned
  • Camber -  thermal position (measured at root)
- Flaps: 5 mm Down
- Ailerons: aligned
  •    Camber - speed position (measured at root)
        - Flaps: 1mm Up
- Ailerons: aligned
  • Butterfly  (measured at the intersection between flaps and ailerons)
- Ailerons: 10 mm Up
        - Flaps: 40mm Down
- Elevator compensation: 4mm down

To conclude, The Rotmilan Midi bring some improvements compared to the standard version, mainly agility at the ailerons and a bit more grip in turn. It remains a very affordable and still competitive F3F plane, with a superb moulding quality.

Hereafter are 2 videos I did in October and November:

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