An apogee event can be programmed on any of the Marsa33LHD 4 channels (8 if including the MarsaNet expansion).

The Marsa33 utilizes the barometric sensor and accelerometer depending on the mode selected to determine apogee.  Apogee event programming is easy as all you need to do is to select one of the robust apogee detection modes.  No need to define timing, rising pressure, speed and so on.

Each of the apogee detection modes are described below.


Apogee Detection Modes

Baro Only

Apogee detection is determine by a drop in altitude from the peak altitude reached during the flight. The amount of drop necessary is determined statistically so that the confidence of apogee detection is 95%.

Baro only apogee is mach immune as the Marsa33 uses the accelerometer to lock out baro events when vertical speed is above 300 feet/sec.

The barometric sensor is not reliable above 45Kft MSL so do not select this mode for flights that are near or above 45Kft MSL

 Accel Only

Apogee detection is determined by determining the point where vertical velocity is zero from integrating the acceleration from launch during flight.  Use this apogee mode when the expected altitude is greater than 45Kft MSL.  Also this mode can be selected if the avionics bay of the rocket cannot be reliability vented to provide a good pressure reading during flight.


 Baro OR Accel

Apogee detection will be either barometric or Accelerometer which evers occurs first. This is the recommended apogee mode for most situations where the altitude of the rocket will not exceed 45Kft.



Apogee will be determined by a Kalman filter processing of both the barometric pressure and accelerometer readings during flight.  This mode is recommended for flights below 45K MSL where an early apogee must be avoided.  Example record altitude attempts.


In addition a delay can be programmed for up to 25.6 seconds in 0.1s increments for any apogee event.