Altimeter cloud: Flight 2621

Paramètres généraux

Pression prévue

Set this to your local forecast pressure at sea level. This will offer you slightly improved accuracty for your flight, although it's not 100% essential every little helps!

Xcweather.co.uk is a decent place to grab pressures from for your location and time.

1026 mbar

Détection lancement

This is the altitude above the launch pad altitude where the altimeter will trigger itself into recording / flight mode.

The altimeter keeps a constant average of the pressure while waiting for launch, it uses a simple algorithm and the pre-flight buffers to do this. The most recent 120 samples (~4 seconds) are ignored so your pre-trigger altitude won't effect the ground baseline.

For almost all uses we suggest keeping this on the 25 Meter (~82 feet) default settings. If you want to test your altimeter by throwing it in the air, or are planning a very low flight you may want to lower the setting.

35 meters

Ratio échantillonnage

The altimeter runs at 50Hz however you can record every sample or every X samples in order to extend the log time. For example if you set the ratio to 1 it will save 1:1 samples, or if you set it to 3 it will save 1 in 3 samples.

1:5 (hybrid, reduces after apogee)

Max. échantillons

This is the maximum samples the altimeter will log per flight. When it reaches this amount it will stop and save the recording.

18000

Arrêt enregistrement

This setting is how the altimeter decides to stop recording. You can choose either 450 (~9s) or 900 (~18s) samples stable or it will record until the max samples limit unless you press the BUTTON in Manual stop mode.

The samples stable method waits for the devices altitude not to change for the set number of samples. This is defined by not changing by more than +/- 1.0 meters for 98% of the samples, it's a reliable method to stop the recording after landing within 8-10 seconds (300 sample) or 16-20 seconds (600 sample).

Auto: 450 samples stable (~9s)

Suréchantillonnage

Oversampling is a internal setting of the BMP 390 pressure sensor. It is how many samples are taken for each reading. By taking multiple samples for each pressure reading the altimeter reduces noise and increases the resolution of the output.

The sensor can run at 50 samples per second in 4X mode, so we suggest leaving it in this mode as it will offer the highest accuracy.

8x Oversampling

Filtre IIR

The IIR filter is another internal sensor for the BMP390 pressure sensor. It is a Infinite impulse response filter used to enhance pressure measurement accuracy by reducing noise. It's primarily for smoothing out rapid pressure changes.

We suggest not setting this too high as it will cause delay to changes in altitude if set very high.

COEFF 7

Filtre pression

This filter is a software Kalman filter that runs on the altimeters processor.

The Kalman filter uses a prediction step based on a system model and then a correction step using new measurements to refine its estimate, it creates accurate most certain results from data with noise in it.

Kalman 2 (default)

Changement verrouillage

This is how we detect a lockout. If the pressure changes by this much in a single sample downwards (pressure increase, lower altitude) then it's likely to be a false reading. Multiply the setting by 32 to get the speed in meters per second that it will trigger at.

0.5 meters

Synchro capteurs

The filters on the pressure sensor can cause it to lag very slightly behind the Accelerometer and Gyroscope data. The Sync sensors option detects how far out of sync these sensors are. It then corrects the Acceleration and Gyroscope readings to match the pressure sensor.

ACTIVÉ (75 samples / 300.00ms)

Orientation

This is the orientation you intend to install the Altimeter in your rocket. It's needed to ensure completly accurate angles and orientation charts and reports. Check out the Manual for more information on this.

Upwards (text up)

Filtre IMU

The IMU filter, or fusion filter takes the data from each axis of the Gyroscope and Accelerometer to calculate the Pitch, Roll, Yaw and tilt angle from vertical. These filters can build up some discrepency over time so it's important to calibrate your sensors to minimise this.

Madgwick 6-Axis

ALP lancement

This is prevention against accidental launch detection.

With this disabled the launch is based only on pressure and something that creates a low pressure can trigger the flight by accident. For example pulling your nose cone off can even trigger it.

With this enabled the rocket also needs to have seen 8 samples (0.25 seconds) of acceleration above this setting in the last 3 seconds as well as the pressure drop to trigger. There is a backup trigger of 1.05 seconds of altitude being above the launch detect setting too.

There are very few situations where this option would cause issues, so we suggest leaving it on.

1.4G

Verrouillage lancement

When enabled, the altimeter locks out recording for a set period after power on to prevent false triggering during setup.

DISABLED

Température statique

A fixed temperature value used for altitude calculation when the external temperature sensor is disabled or not connected.

15 °C

Capteur temp.

If an external MT1 temperature sensor is connected, this controls whether it is used for logging only or also for altitude calculations.

DISABLED

Paramètres de sortie

Arm switch

When enabled, GP6 is a hardware arm switch — outputs and rules are held off until the switch is closed to ground.

DISABLED

Startup lockout

Outputs and rules are blocked for this many seconds after power-on while sensors settle. 0 = off.

None

Launch confirm delay

After launch is detected, outputs and rules won't fire until this many seconds have passed.

2 s

Altitude floor

Outputs and rules are blocked until the rocket is at least this height above the launch pad.

50 m

Custom dataset 1

User-defined expression evaluated per sample, available for charting.

—

Custom dataset 2

—

Étalonnage capteurs

Décalages de calibration utilisés pour ce vol.

Gyroscope⚠ Le gyroscope n’a pas été calibré

X0.000°

Y0.000°

Z0.000°

Accéléromètre⚠ L’accéléromètre n’a pas été calibré

X0.000 mG

Y0.000 mG

Z0.000 mG

Paramètres appareil

TAG appareil

A custom name or tag assigned to this device for easy identification.

Merc9448

Langue

The language setting configured on the device.

🇬🇧 English

Mode arrêt

Controls what happens after recording. Standard shuts down normally, Delayed keeps WiFi on for 30 seconds after landing, Stay on keeps the device powered on.

Standard

Luminosité LED

The brightness level of the LED indicators on the Mercury. Lower values save battery.

20%

Puissance WiFi TX

WiFi transmit power level. Higher gives better range but uses more battery.

2 dBm (low)

Mode veille

Controls whether the device enters low-power sleep when idle.

Normal (sleep when idle)

Surveillance batterie

Monitors battery voltage during the flight.

DISABLED

Groupe cloud

The cloud group / category this flight is assigned to.

General use

Ports GP6 / GP7

Configuration des ports GP6 et GP7 pour canaux pyro, servos ou autres appareils.

Mode canal 6

ON = HIGH

Ch6 min pulse (µs)

Ch6 max pulse (µs)

Ch6 frequency

0 Hz

Ch6 angle ON

0°

Ch6 angle OFF

0°

Ch6 on time

Mode canal 7

ON = HIGH

Ch7 min pulse (µs)

Ch7 max pulse (µs)

Ch7 frequency

0 Hz

Ch7 angle ON

0°

Ch7 angle OFF

0°

Ch7 on time

Carte servo I2C PCA9685

Configuration de la carte servo externe I2C PCA9685 avec jusqu’à 6 canaux servo supplémentaires.

Aucune carte servo I2C n’était connectée pour ce vol.

Prédiction et aérofreins

Le Mercury peut prédire l’apogée pendant la phase de vol libre. Ces paramètres contrôlent le calcul et le système d’aérofrein.

Masse sèche

The total mass of the rocket after motor burnout (dry mass). This is used for the ballistic prediction of apogee altitude. Enter the mass without the motor propellant, or the mass at burnout.

0.15 kg

Coefficient Cx

The aerodynamic drag coefficient (Cd) of the rocket. This is used with the rocket area to calculate aerodynamic drag during coast. A typical model rocket has a Cd of 0.4 to 0.8. You can find this value from OpenRocket or RockSim simulations.

0.75

Surface référence

The cross-sectional reference area of the rocket in square meters. This is typically the area of a circle with the body tube diameter. For example a 38mm tube has an area of approximately 0.00113 m².

0.001 m²

Gas constant

The specific gas constant for dry air, used in the atmospheric model for altitude and density calculations. The standard value is 287.05 J/(kg·K). You shouldn't need to change this unless you know what you're doing.

287.05 J/(kg·K)

Les paramètres suivants configurent le système d’aérofrein.

Aérofrein activé

Enables or disables the active air braking system. When enabled, the Mercury will deploy air brakes via the configured servo channel to try and reach the target altitude. Firmware 2.1+ required.

OFF (default)

Servo channel

Which servo output channel the air brake mechanism is connected to. GP6 and GP7 are the two onboard servo headers, I2C channels are for an external servo expander board.

GP6

Deploy speed

The speed at which the air brakes deploy. The Mercury gradually increases the servo angle until the predicted apogee matches the target rather than going full on/off. This setting controls how quickly it ramps up to full braking.

Medium (default)

Altitude cible

The target apogee altitude in meters. The air brake system will try to slow the rocket so it reaches this altitude.

300 m

Over shoot %

The percentage over the target altitude to aim for until within 15% of the target. This helps prevent undershooting if the prediction is slightly off early in the coast. For example, with a 1000m target and 5% early adjustment, the Mercury will aim for 1050m until it passes 850m.

Activation altitude

The air brake system activates after burnout, but won't engage until the rocket has reached this percentage of the target altitude. This prevents the brakes from deploying too early when predictions may be less accurate.

20% (default)

Iris Flight 3

The flight, moment by moment

Stabilité68.8%Modéré

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Apogee, adjusted for conditions

FLIGHT 2621

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Apogee, adjusted for conditions

FLIGHT 2621

BURNOUT

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