arduplane auto takeoff problem

[nabakou]

hello guys,

i have a Skyfun mounted with HK red board / arduplane 2.76 , with pitot tube it flies very well : stabilise/loiter/rtl/auto/cruise/acro/fbwb

i've done a flight plan with first step :takeoff to 30 m and then waypoints

let's the plane on the ground ready to takeoff with bungee: when i put "auto mode" on the radio, after 5-6 seconds, the motor starts full throttle even i set some values to "tkoff_thr_minspd" or "tkoff_thr_acc" ....and even the throttle is on zero on the emitter...

[smurfy]

I think what you are seeing is the intended behavior. Have a look:

http://plane.ardupilot.com/wiki/flying/automatic-takeoff-and-landing/

[nabakou]

hello Andreas,

i've seen that page before but it doesn't help me all works as the TKoff parameters are not taken into account

[smurfy]

To quote the offical site:

The basic idea of automatic takeoff is for the APM to set the throttle to maximum and climb until a designated altitude is reached.

Also based on a quick look at the code there is no paramter to restrict the max throttle for takeoff. Only the following parameters exists:

// @Param: TKOFF_THR_MINSPD
// @DisplayName: Takeoff throttle min speed
// @Description: Minimum GPS ground speed in m/s used by the speed check that un-suppresses throttle in auto-takeoff. This can be be used for catapult launches where you want the motor to engage only after the plane leaves the catapult, but it is preferable to use the TKOFF_THR_MINACC and TKOFF_THR_DELAY parameters for cvatapult launches due to the errors associated with GPS measurements. For hand launches with a pusher prop it is strongly advised that this parameter be set to a value no less than 4 m/s to provide additional protection against premature motor start. Note that the GPS velocity will lag the real velocity by about 0.5 seconds. The ground speed check is delayed by the TKOFF_THR_DELAY parameter.
// @Units: m/s
// @Range: 0 30
// @Increment: 0.1
// @User: User
GSCALAR(takeoff_throttle_min_speed, "TKOFF_THR_MINSPD", 0),

// @Param: TKOFF_THR_MINACC
// @DisplayName: Takeoff throttle min acceleration
// @Description: Minimum forward acceleration in m/s/s before arming the ground speed check in auto-takeoff. This is meant to be used for hand launches. Setting this value to 0 disables the acceleration test which means the ground speed check will always be armed which could allow GPS velocity jumps to start the engine. For hand launches this should be set to 15.
// @Units: m/s/s
// @Range: 0 30
// @Increment: 0.1
// @User: User
GSCALAR(takeoff_throttle_min_accel, "TKOFF_THR_MINACC", 0),

// @Param: TKOFF_THR_DELAY
// @DisplayName: Takeoff throttle delay
// @Description: This parameter sets the time delay (in 1/10ths of a second) that the ground speed check is delayed after the forward acceleration check controlled by TKOFF_THR_MINACC has passed. For hand launches with pusher propellers it is essential that this is set to a value of no less than 2 (0.2 seconds) to ensure that the aircraft is safely clear of the throwers arm before the motor can start.
// @Units: 0.1 seconds
// @Range: 0 15
// @Increment: 1
// @User: User
GSCALAR(takeoff_throttle_delay, "TKOFF_THR_DELAY", 2),

In auto takeoff it sets the throttle to max. You can restrict the max throttle value, but it will apply to everything not just the takeoff.

// @Param: THR_MAX
// @DisplayName: Maximum Throttle
// @Description: The maximum throttle setting to which the autopilot will apply.
// @Units: Percent
// @Range: 0 100
// @Increment: 1
// @User: Standard
ASCALAR(throttle_max, "THR_MAX", THROTTLE_MAX),

Hope this helps. Also it seams this is an ardupilot "issue" not an mpng one :D

[nabakou]

:oP

thank You for answer it's not very important for me if auto takeoff doesn't work, i'll try another time at the field for auto-landing Anyway, the plane flies very well, even with windy conditions, just a technologic miracle !