Profile image

XC-204 Grasshopper

8,548 Synthex4060  5.4 years ago
392 downloads

Don't know if you feel like driving or flying ? Here is the vehicle you need !ù This little guy is a car and a plane !
Controls :
-AG1: Headlights / Landing lights
-AG2: Signal lights / Navigation lights
-AG4: Left turning light
-AG5: Right turning light
-AG6: Stabilizator gyro
-AG7: Jet engines (0 when de-activated)
-AG8: Combustion engine (FWD - 0 when de-activated)

The pitch inertia of this plane is of course higher than normal so prolonged pitch action can result in a spin. Go easy on the elevators when near the ground, and use the gyro (AG6) to recover after a spin).

General Characteristics

  • Created On Windows
  • Wingspan 24.6ft (7.5m)
  • Length 31.8ft (9.7m)
  • Height 7.8ft (2.4m)
  • Empty Weight 4,456lbs (2,021kg)
  • Loaded Weight 6,571lbs (2,980kg)

Performance

  • Power/Weight Ratio 1.025
  • Wing Loading 27.9lbs/ft2 (136.5kg/m2)
  • Wing Area 235.1ft2 (21.8m2)
  • Drag Points 3923

Parts

  • Number of Parts 158
  • Control Surfaces 14
  • Performance Cost 607
  • Log in to leave a comment
  • Profile image
    8,548 Synthex4060

    @Giggitymerf
    I could shift the CoG forward, but then the CoL is too far back. The idea here was to have a CoG roughly in the middle of 4 equally loaded wheels as well as 4 equally loaded wings, so the CoG/CoL location is pretty much determined by that. Such a design is automatically pitch-heavy because of the weight distribution. And because of the 2 set of wings, the pitch control is less stable (hard to explain without schematics).

    The pitch surfaces I set just so that you can maneuver confortably but not too sensitive so you don't get into spins too easily. You can fully pull the yoke for a short moment, it will still be stable enough, but if you do so too long then it might lose control. The gyro is just here to recover from that.

    If you think about it, most subsonic planes have wings that have a long span but are not very long. In terms of load-spreading this is far from ideal. A long wingspan means a big bending moment on the wing-fuselage connection, and only the middle of the fuselage is well supported. So all the heavy stuff is put in the middle.

    In that regard a longer wing with less wingspan would be better. But that would lead to more turbulent airflow on the wings, so less efficiency. Then why not 4 or even 6 smaller wings instead of 2 ?
    Now you can spread the weight of your cargo and engines over a longer span. Better for the structure ! But now your pitch inertia get's quite high.

    And there is also the unstability effect. You're not just pitching about a songle Col/CoG but it's more like have 2 CoL's and one CoG, and you get higher pitch moment's beyond a certain angle of attack.

    TL:DR
    The unstability is inherent to the design. The plane behaves just fine if you don't do anything too crazy, the gyro is just here to recover from spins if you do go over the line.

    5.4 years ago