What does it feel like to handle?
Fly it
The project’s own 6-DOF solver at 100 Hz, with the full added-mass tensor. Slow to respond, slow to stop, and overdamped at cruise where it wallows at rest.
Fly it
This runs the project's own 6-DOF solver at 100 Hz, not a simplified version for the browser. The same step function the validation gates exercise is called here, so if the vehicle feels wrong there is no second implementation to blame. Expect it to be slow to respond and slow to stop: the displaced air nearly doubles the effective mass in sway and heave.
Click the view, then W and S for thrust, arrow keys for elevator and rudder, Q and E to drop and take on ballast. Loading.
Two things it does that an aeroplane does not
It wallows when stopped and is dead-beat under way. The pitch pendulum has a period around thirty seconds and no aerodynamic damping at zero airspeed, because the fins have no dynamic pressure to work with. Above about 10 m/s the same mode is overdamped. Both are correct, the difference is large, and a control law tuned at one end will misbehave at the other.
The fins are enormous, and they have to be. Setting the fin restoring moment against the Munk moment, the dynamic pressure and the incidence both cancel, leaving a minimum area that is independent of speed and altitude. For this hull it is about 174 m². A first guess of 60 m² diverged just as surely as no fins at all: below the minimum there is no partial credit.
Move a parameter and watch what breaks
Every figure here is recomputed by the same solvers the tests and the reports use. Infeasible regions are shown as infeasible rather than as a small number: a hull that cannot lift its own structure says so, and a wind the vehicle cannot hold against turns the verdict red.
Every figure recomputed by the same solvers the tests and the reports use. A hull length change costs about 300 ms because the solar year is integrated again from scratch, so the panel dims while a result is stale rather than showing a number that is no longer current.