Xem Studiomeasured geometry

Library › Aircraft design › Wing features ·

Fowler flap

What makes a Fowler flap different? · Standard part · basis: Design rules and figures from the cited sources; example geometry by Xem Studio

Also called: fowler flaps, fowler flap rc, sliding flap, extending flap, fowler flap mechanism, fowler vs slotted flap, track flap

Exact dimensions. True size, with no printing tolerance added.

sizes
5 in table

Notes

  • A Fowler flap slides aft on tracks before drooping, increasing both wing area and camber; early extension adds lift with little drag, late extension adds drag with little lift (FAA PHAK ch.6).
  • Its section CLmax increment is 1.3 x c'/c, where c' is the extended chord; double-slotted Fowler reaches 1.6 x c'/c and triple-slotted 1.9 x c'/c (Arnedo, Franchini data).
  • The file is a reference example built by Xem Studio from the numbers above. Sizes the sources do not fix are illustrative; scale the example to your own vehicle.

Fowler flap size chart

parametervalue or rangesource
Section delta-CLmax1.3 c'/cArnedo (Franchini)
Double slotted Fowler1.6 c'/cArnedo
Triple slotted Fowler1.9 c'/cArnedo
Typical CLmax/cos(sweep), Fowler flap2.0-2.2 takeoff (15 deg) / 2.5-2.9 landing (40 deg)Arnedo
Reference buildchord 100, 30% flap, 40 degillustrative

Where the files are

Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.

FAAPilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25), Ch. 6 Flight ControlswebPublisher's page; dimensions are facts
LibreTexts (Arnedo, Fundamentals of Aerospace Engineering; data from Franchini et al.)3.4.3 Increase in CLmax (high-lift devices)webPublisher's page; dimensions are facts

Free files

★ Free files 1 parts. Xem Studio design: free to use, print and sell things from; not to be republished as files. Xem Studio Design License. index.json

fowler-flap-wing-segmentfowler flap: wing segment 100 mm chord × 300 mm, 30 % chord surface deflected 40°STEP · STL
Let your AI pull this. Add https://xemstudio.com/mcp to Claude, ChatGPT, Cursor or any MCP client (free, no account, one minute) and it can look up exact sizes, mating fits and free STEP/STL from every chat.
Set it up →

Plain text: sheet.txt · JSON: /api/geometry?object=fowler-flap

Fowler flap, isometric render of a generated part
Render of fowler-flap-wing-segment from the free STEP; not to scale.

Fits with

Plain flap, isometric render of a generated part
Plain flap6 sizes★ 1 file
Split flap, isometric render of a generated part
Split flap3 sizes★ 1 file
Slotted flap, isometric render of a generated part
Slotted flap5 sizes★ 1 file
Leading-edge slat and fixed slot, isometric render of a generated part
Leading-edge slat and fixed slot5 sizes★ 1 file
Gurney flap, isometric render of a generated part
Gurney flap5 sizes★ 1 file
Leading-edge cuff (drooped leading edge), isometric render of a generated part
Leading-edge cuff (drooped leading edge)4 sizes★ 1 file

Questions

Why do airliners use Fowler flaps?

They add area and camber, giving the highest CLmax of common flaps (Arnedo).