How do I install the Fuel Tank Sizing skill?

Run npx skillmds@latest add ashfordeou/fuel-tank-sizing 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.

Is Fuel Tank Sizing safe to use?

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Which AI agents work with Fuel Tank Sizing?

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 Fuel Tank Sizing free to use?

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

Who published Fuel Tank Sizing?

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

Fuel Tank Sizing by ashfordeou — Agent Skill

Name: Fuel Tank Sizing
Author: ashfordeOU

Fuel Tank Sizing

Use when you must size the fuel tanks for the aircraft: convert the fuel mass to the fuel volume with the fuel density, add the ullage allowance to get the required tank volume, and check it against the available volume in the wing and fuselage tanks. Produces the usable fuel volume, the required tank volume with ullage, and the fits verdict that gate the fuel system sizing. Trigger: fuel tank sizing, ullage, fuel volume, usable fuel, tank capacity.

ashfordeOU Updated Sep 17, 2026

File contents

Fuel Tank Sizing (vehicle-design/sizing/fuel-tank-sizing)

Use when the task is sizing the fuel tanks at the conceptual level: converting the fuel mass into a fuel volume with the fuel density, adding the ullage allowance to get the required tank volume, and checking that volume against the volume available in the wing and fuselage tanks.

Domain quick reference

Fuel volume is the fuel mass divided by the fuel density; jet fuel density is commonly about 0.8 kg per liter, or 800 kg per cubic meter.
Volume units: liters for tank bookkeeping, cubic meters for the wing box and fuselage volume checks; one cubic meter is 1000 liters.
Ullage is the allowance for fuel expansion and tank venting space, added on top of the usable fuel volume; typical values are a few percent of the usable volume.
Required tank volume: usable fuel volume times (1 + ullage fraction).
The fits verdict subtracts the required tank volume from the available volume; a non-negative margin fits, and the margin percent is relative to the required volume.
Fuel tank sizing sits in the FAR-25 / CS-25 fuel system context (fuel quantity, unusable fuel, and expansion space for the tank).

Workflow

Collect the fuel mass in kg, the fuel density in kg per liter, the ullage fraction, and the available tank volume in liters.
Compute the usable fuel volume with fuel_volume_liters (and the cubic meter value with fuel_volume_m3 for the structure check).
Add the ullage allowance with tank_volume_with_ullage, or use required_tank_volume directly.
Check the required volume against the available volume with check_available_volume and read the fits verdict.

Pitfalls

Mixing density units: 0.8 kg per liter is 800 kg per cubic meter; using the wrong one changes the volume by a factor of 1000.
Forgetting the ullage allowance: the tank must hold the fuel plus the expansion and venting space, not the fuel alone.
Checking against the total aircraft volume instead of the volume actually available in the wing box and fuselage tanks.
Passing a zero fuel mass or a negative ullage; the module raises ValueError instead of guessing.

Behavior contract (gate 3)

The volume conversion, ullage, required tank volume, and fits verdict logic are exercised by the gate 3 contract test: scripts/test_fuel_tank_sizing.py against scripts/fuel_tank_sizing_logic.py (stdlib unittest, offline). Run: python3 scripts/test_fuel_tank_sizing.py

Compliance

Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the volume and ullage calculations are common fuel system sizing methodology, summary-only per standards-map.yaml.
compliance: STANDARDS-REF, gated: false.

---name: fuel-tank-sizingdescription: Use when you must size the fuel tanks for the aircraft: convert the fuel mass to the fuel volume with the fuel density, add the ullage allowance to get the required tank volume, and check it against the available volume in the wing and fuselage tanks. Produces the usable fuel volume, the required tank volume with ullage, and the fits verdict that gate the fuel system sizing. Trigger: fuel tank sizing, ullage, fuel volume, usable fuel, tank capacity.license: Apache-2.0---# Fuel Tank Sizing (vehicle-design/sizing/fuel-tank-sizing)Use when the task is sizing the fuel tanks at the conceptual level:converting the fuel mass into a fuel volume with the fuel density,adding the ullage allowance to get the required tank volume, andchecking that volume against the volume available in the wing andfuselage tanks.## Domain quick reference- Fuel volume is the fuel mass divided by the fuel density; jet fuel density is commonly about 0.8 kg per liter, or 800 kg per cubic meter.- Volume units: liters for tank bookkeeping, cubic meters for the wing box and fuselage volume checks; one cubic meter is 1000 liters.- Ullage is the allowance for fuel expansion and tank venting space, added on top of the usable fuel volume; typical values are a few percent of the usable volume.- Required tank volume: usable fuel volume times (1 + ullage fraction).- The fits verdict subtracts the required tank volume from the available volume; a non-negative margin fits, and the margin percent is relative to the required volume.- Fuel tank sizing sits in the FAR-25 / CS-25 fuel system context (fuel quantity, unusable fuel, and expansion space for the tank).## Workflow1. Collect the fuel mass in kg, the fuel density in kg per liter, the ullage fraction, and the available tank volume in liters.2. Compute the usable fuel volume with fuel_volume_liters (and the cubic meter value with fuel_volume_m3 for the structure check).3. Add the ullage allowance with tank_volume_with_ullage, or use required_tank_volume directly.4. Check the required volume against the available volume with check_available_volume and read the fits verdict.## Pitfalls- Mixing density units: 0.8 kg per liter is 800 kg per cubic meter; using the wrong one changes the volume by a factor of 1000.- Forgetting the ullage allowance: the tank must hold the fuel plus the expansion and venting space, not the fuel alone.- Checking against the total aircraft volume instead of the volume actually available in the wing box and fuselage tanks.- Passing a zero fuel mass or a negative ullage; the module raises ValueError instead of guessing.## Behavior contract (gate 3)The volume conversion, ullage, required tank volume, and fits verdictlogic are exercised by the gate 3 contract test:scripts/test_fuel_tank_sizing.py againstscripts/fuel_tank_sizing_logic.py (stdlib unittest, offline). Run:python3 scripts/test_fuel_tank_sizing.py## Compliance- Standards referenced, not reproduced: FAR-25 is US government work (public domain) and CS-25 is a free EASA download; the volume and ullage calculations are common fuel system sizing methodology, summary-only per standards-map.yaml.- compliance: STANDARDS-REF, gated: false.

Frequently asked questions