CALCULATORS / AERODYNAMICS AND FLIGHT SCREENING

Glide ratio and descent calculator

Steady still-air glide from supplied lift/drag ratio.

aerodynamics-glide.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	anglerad	rangem	sinkRatem/s
	0.0996687	1000	1.19404
	0.0996687	800	1.19404

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

glide range target1000.00 m✓ passes

BASELINE INPUTS

altitude100 mliftDrag10 airspeed12 m/s

CALCULATED

angle0.099669 rad

range1000 m

sinkRate1.194 m/s

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Glide ratio and descent
# Scope: Steady still-air glide from supplied lift/drag ratio.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

altitude = 100 m
liftDrag = 10
airspeed = 12 m/s

angle := atan(1/liftDrag) [rad]
range := altitude*liftDrag [m]
sinkRate := airspeed*sin(angle) [m/s]

check glide range target: range >= 800 m

scenario alternative: altitude = 80 m

Calculated from your source · not saved

Baseline · Baseline

glide range target1000.00 m ✓ passes

alternative · alternative

glide range target800.00 m ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

angle: angle = atan(1/liftDrag) [rad]
range: range = altitude*liftDrag [m]
sink rate: sinkRate = airspeed*sin(angle) [m/s]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

altitude: 100 m
lift drag: 10
airspeed: 12 m/s

Calculated

angle: 0.0996687 rad
range: 1000 m
sink rate: 1.19404 m/s

Assumptions and limits

Steady still-air glide from supplied lift/drag ratio.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Glide ratio and descent. Inputs: lift-to-drag ratio; altitude; airspeed. Outputs: glide distance; descent rate. Model scope: Coefficient-based models over an explicitly limited flight regime. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: lift-to-drag ratio, altitude, airspeed
Outputs: glide distance, descent rate
Modes: calculate, compare, sweep
Drawing: Force and flight-envelope plots

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS