How do I install the Breguet Endurance skill?

Run npx skillmds@latest add ashfordeou/breguet-endurance in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Which AI agents work with Breguet Endurance?

This skill is tagged as working with Claude Code, Claude.ai, OpenAI Codex. SKILL.md is an open format, so most agents that read a skills directory can load it too.

Is Breguet Endurance free to use?

Yes. Installing skills from SkillMD is free. This skill is licensed under Apache-2.

Who published Breguet Endurance?

ashfordeOU (@ashfordeou) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Breguet Endurance by ashfordeou — Agent Skill

Name: Breguet Endurance
Author: ashfordeOU

Breguet Endurance

Use when you must compute the loiter endurance time of an aircraft with the Breguet endurance equation: combine the specific fuel consumption and the lift to drag ratio with the initial and final weights to produce the holding endurance in seconds, the final weight after an endurance segment, and the fuel burn for the loiter requirement. Produces the endurance time, final weight, and fuel burn that gate the holding performance check. Trigger: loiter endurance, endurance equation, holding time, specific fuel consumption, lift to drag ratio, fuel burn, maximum endurance.

ashfordeOU Updated Sep 17, 2026

File contents

Breguet Endurance (flight-mechanics/performance/breguet-endurance)

Use when the task is loiter endurance (holding time) estimation from the Breguet endurance equation: specific fuel consumption, lift-to-drag, and the initial and final weights, plus the final weight after an endurance segment and the fuel burn for the loiter requirement.

Domain quick reference

The Breguet endurance equation computes loiter endurance (holding time) E from the specific fuel consumption sfc, the lift to drag ratio L/D, and the initial and final weights W0 and W1: E = (1 / sfc) * (L/D) * ln(W0 / W1).
Units: sfc in 1/s (kg of fuel per newton of thrust per second for a jet, kg of fuel per watt of shaft power per second for a propeller), weights in newtons, endurance in seconds. All SI.
Final weight after an endurance segment at constant L/D: W1 = W0 * exp(-E * sfc / (L/D)).
Fuel burn for the segment: W0 - W1.
Endurance is maximized at the maximum lift to drag ratio (L/D)max, the minimum-thrust condition; the loiter performance check compares the achievable endurance against the required holding time.
Endurance analysis sits in the FAR-25 / CS-25 transport performance context for holding fuel planning.

Workflow

Collect the specific fuel consumption, the lift to drag ratio, and the initial and final weights.
Compute the endurance with jet_endurance (or prop_endurance for a propeller aircraft).
Compute the final weight after the holding segment with final_weight_after_endurance.
Compute the fuel burn with endurance_fuel_burn.
Check the loiter requirement with loiter_check before gating.

Pitfalls

Confusing the SFC basis: jet endurance needs thrust specific fuel consumption in kg/(N s) (1/s), propeller endurance needs the consumption referred to shaft power in kg/(W s), also 1/s. Mixing the bases misstates the endurance.
Using SFC in 1/h or lb/(lbf h); the equation needs per-second units, so convert before computing.
Confusing endurance with range: endurance is a loiter (holding) time problem, E = (1/sfc) * (L/D) * ln(W0/W1), while the Breguet range equation adds speed and a gravity conversion for cruise distance. Do not apply the range equation to holding.
Flipping the weight ratio: endurance requires burning fuel, so W1 must stay below W0; W1 >= W0 makes ln(W0/W1) undefined or negative.
Assuming endurance grows with speed: holding time depends on L/D and SFC only, not on speed; (L/D)max is the maximum-endurance condition.

Behavior contract (gate 3)

The loiter endurance logic is exercised by the gate 3 contract test: scripts/test_breguet_endurance_logic.py against scripts/breguet_endurance_logic.py (stdlib unittest, offline). Run:

python3 scripts/test_breguet_endurance_logic.py

Compliance

Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the Breguet endurance equation is common endurance methodology, summary-only per standards-map.yaml.
compliance: STANDARDS-REF, gated: false.

---name: breguet-endurancedescription: Use when you must compute the loiter endurance time of an aircraft with the Breguet endurance equation: combine the specific fuel consumption and the lift to drag ratio with the initial and final weights to produce the holding endurance in seconds, the final weight after an endurance segment, and the fuel burn for the loiter requirement. Produces the endurance time, final weight, and fuel burn that gate the holding performance check. Trigger: loiter endurance, endurance equation, holding time, specific fuel consumption, lift to drag ratio, fuel burn, maximum endurance.license: Apache-2.0---# Breguet Endurance (flight-mechanics/performance/breguet-endurance)Use when the task is loiter endurance (holding time) estimation fromthe Breguet endurance equation: specific fuel consumption,lift-to-drag, and the initial and final weights, plus the finalweight after an endurance segment and the fuel burn for the loiterrequirement.## Domain quick reference- The Breguet endurance equation computes loiter endurance (holding time) E from the specific fuel consumption sfc, the lift to drag ratio L/D, and the initial and final weights W0 and W1: E = (1 / sfc) * (L/D) * ln(W0 / W1).- Units: sfc in 1/s (kg of fuel per newton of thrust per second for a jet, kg of fuel per watt of shaft power per second for a propeller), weights in newtons, endurance in seconds. All SI.- Final weight after an endurance segment at constant L/D: W1 = W0 * exp(-E * sfc / (L/D)).- Fuel burn for the segment: W0 - W1.- Endurance is maximized at the maximum lift to drag ratio (L/D)max, the minimum-thrust condition; the loiter performance check compares the achievable endurance against the required holding time.- Endurance analysis sits in the FAR-25 / CS-25 transport performance context for holding fuel planning.## Workflow1. Collect the specific fuel consumption, the lift to drag ratio, and the initial and final weights.2. Compute the endurance with jet_endurance (or prop_endurance for a propeller aircraft).3. Compute the final weight after the holding segment with final_weight_after_endurance.4. Compute the fuel burn with endurance_fuel_burn.5. Check the loiter requirement with loiter_check before gating.## Pitfalls- Confusing the SFC basis: jet endurance needs thrust specific fuel consumption in kg/(N s) (1/s), propeller endurance needs the consumption referred to shaft power in kg/(W s), also 1/s. Mixing the bases misstates the endurance.- Using SFC in 1/h or lb/(lbf h); the equation needs per-second units, so convert before computing.- Confusing endurance with range: endurance is a loiter (holding) time problem, E = (1/sfc) * (L/D) * ln(W0/W1), while the Breguet range equation adds speed and a gravity conversion for cruise distance. Do not apply the range equation to holding.- Flipping the weight ratio: endurance requires burning fuel, so W1 must stay below W0; W1 >= W0 makes ln(W0/W1) undefined or negative.- Assuming endurance grows with speed: holding time depends on L/D and SFC only, not on speed; (L/D)max is the maximum-endurance condition.## Behavior contract (gate 3)The loiter endurance logic is exercised by the gate 3 contract test:scripts/test_breguet_endurance_logic.py againstscripts/breguet_endurance_logic.py (stdlib unittest, offline). Run:python3 scripts/test_breguet_endurance_logic.py## Compliance- Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the Breguet endurance equation is common endurance methodology, summary-only per standards-map.yaml.- compliance: STANDARDS-REF, gated: false.

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