Lift Calculation

Quick Release automatically calculates whether your balloon has enough lift to fly safely, replacing the need for traditional paper load charts. The calculation is based on the Archimedes principle and the ideal gas law — the same physics behind traditional load charts, but computed precisely for your specific flight conditions.

Feature location#

The lift calculation is displayed in the Lift panel on the flight detail page:

1. Navigate to Flights.
2. Open a flight.
3. Expand the Lift panel.

The panel header shows a quick summary with the spare lift in kg and a scale badge whose colour tells you the warning zone (see below). The same badge appears on the flight card and on the pilot’s mobile view.

How it works#

The Physics#

A hot air balloon flies because heated air inside the envelope is less dense than the cooler air outside. The difference in density creates buoyancy — this is Archimedes’ principle. The lift force equals:

Lift = (ρ_cold − ρ_hot) × Volume × g

Where ρ is air density, Volume is the envelope volume, and g is gravitational acceleration.

Using the ideal gas law (P × V = n × R × T), air density can be expressed as:

ρ = (M × P) / (R × T)

Where M is the molar mass of air, P is atmospheric pressure, R is the universal gas constant, and T is temperature in Kelvin.

Since pressure and molar mass are the same inside and outside the balloon, the formula simplifies to:

Lift = (M / R) × Volume × P × (1/T_cold − 1/T_hot)

This shows that lift depends primarily on:

• The temperature difference between outside air and heated air inside the envelope
• The atmospheric pressure at flight altitude
• The volume of the balloon envelope

Why altitude matters#

Both pressure and temperature decrease with altitude:

• Temperature drops at approximately 6.5 °C per 1000 m (the standard tropospheric lapse rate)
• Pressure decreases following the barometric formula: P_altitude = P_ground × e^(−Mgh / RT)

Since lift depends on pressure and temperature at your maximum flight altitude, Quick Release calculates these values from ground-level conditions and your planned maximum height.

Lift Panel Fields#

The Lift panel is divided into three sections: results, parameters (inputs you can adjust), and calculations (derived values).

Results#

These read-only fields show the outcome of the lift calculation:

Parameters#

These are the input fields you can adjust to match actual flight conditions:

Tip: If weather forecast data is available for the flight, a button is shown with the forecasted temperature and pressure. Click it to copy those values into the parameters.

Calculations#

These read-only fields show intermediate values derived from the parameters:

Location Elevation#

The takeoff height is not entered manually — it is automatically determined when a location is created or geocoded in Quick Release. When an operator enters an address for a location, the system:

1. Calls the Google Maps Geocoding API to resolve the address into GPS coordinates (latitude and longitude).
2. Calls the Google Maps Elevation API with those coordinates to obtain the ground elevation in meters.
3. Converts the elevation from meters to feet and stores it on the location record.

This ensures the elevation used in the lift calculation is accurate and consistent, without relying on manual input.

Lift warning zones#

The scale badge next to the spare lift shows one of four zones:

The zones are informational — the pilot always decides.

Configuring the limits#

The right limits depend on the balloon, so they are set per balloon: go to Resources → Balloons, open a balloon and find the lift warning zones section. A coloured bar previews your red, orange and green ranges while you enter the two limits:

• doubtful (orange) from — below this value the flight shows red
• good (green) from — from this value the flight shows green (a common choice is one passenger weight, 75 kg, above the orange limit)

Both limits start at 0, which reproduces the old behaviour: only a negative spare lift shows red. The blue zone needs no limit — it activates as soon as the balloon has an MLM filled in, and compares it against the worst-case landing mass (takeoff mass minus the full gas weight of the cylinders).

Freshness#

For upcoming flights on automatic Meteoblue weather, the lift calculation uses the latest forecast values for takeoff temperature and pressure whenever it is displayed — the flight no longer has to be opened first. A manually entered takeoff temperature keeps priority; completed flights keep their recorded weather.

What counts as “Needed Lift”#

The needed lift is the sum of everything the balloon must carry:

Note: Only passengers with booking status Confirmed are included in the weight calculation.

Passenger Weight#

Each passenger’s weight is provided by the booking contact when making or updating their booking. If the contact has not yet entered a weight, the system assigns a default weight of 75 kg per passenger.

When any passenger on a flight is still using the default weight, a warning icon (⚖️ scale icon in orange) is shown in the Passengers panel header. This alerts the operator that the lift calculation may not be accurate and that actual weights should be collected before the flight.

The lift calculation always adds 4 kg for clothing and 3 kg for luggage on top of each passenger’s weight (whether actual or default).

Data Validation#

The Lift panel will show a warning and list missing data if any required information is not available:

• No launch location assigned to the flight
• No balloon volume configured (or volume is 0)
• No balloon weight configured (envelope + basket + burner must have weights)
• No pilot assigned, or pilot has no medical weight recorded

Resolve these issues in the respective resource records (balloon, location, crew) to enable the lift calculation.

Operational Flight Plan (Manifest)#

The lift calculation results are not only displayed in the application — they are also printed on the Operational Flight Plan (manifest), the official document the pilot carries on board. The manifest includes a Load Chart section and a Passenger List with weight details.

Load Chart#

The Load Chart on the manifest contains the following fields:

Below the load chart, a weight breakdown shows the individual equipment weights:

Passenger List#

The passenger list on the manifest shows each confirmed passenger with their individual weight followed by (+7kg) — representing the combined clothing (4 kg) and luggage (3 kg) allowance.

At the bottom, a Totals row shows the combined weight of all passengers plus the pilot, which corresponds to the people portion of the “Lift Needed” value.

Prerequisites#

For accurate lift calculations, ensure the following records are properly configured:

1. Balloon — envelope volume, envelope weight, basket weight, burner weight, and cylinder full weights (see Add a Balloon)
2. Location — elevation in feet (see Add a Location)
3. Pilot — medical weight (see Add Crew)
4. Passengers — individual weights for each confirmed booking