RPM sensor output

                rpm1                      : RPM Sensor1 (float)
                rpm2                      : RPM Sensor2 (float)

def rpm_send(self, rpm1, rpm2, force_mavlink1=False):
                '''
                RPM sensor output

                rpm1                      : RPM Sensor1 (float)
                rpm2                      : RPM Sensor2 (float)

                '''
                return self.send(self.rpm_encode(rpm1, rpm2), force_mavlink1=force_mavlink1)