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Open design plane

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Open Design Aircraft, From Homebuilt Planes to Open Source Flight

This page is a general overview and not engineering, legal, or safety advice. Building or flying aircraft involves serious risk, and regulations differ by country and change over time, so check with your aviation authority and qualified people before acting.

What does it take to design an aircraft that is open, and can one person do it? This page works through both questions in plain terms.

An open aircraft design is one where the plans, the tools, and the test records are published so that other people can study them, copy them, check them, and improve them. This page serves several goals of this wiki at once:

  • Abundance and post-scarcity. Flying remains out of reach for many people. Shared designs and free tools are one way to push toward lower cost and falling prices, though this page makes no promise that any particular project will get there. See post-scarcity economy for the wider idea.
  • Learning, teaching, and research. Aircraft design joins aerodynamics, structures, controls, and materials. Open plans and open software let students and hobbyists learn by doing, in the spirit of why open design.
  • Freedom tech and decentralization. When plans and tools live in many hands, no single company or agency has to be the only source of knowledge. See mesh networks as freedom infrastructure and local-first software and data ownership for related ideas.
  • Verifiable engineering. Published calculations, build logs, and flight test data can be checked by anyone, which is a different kind of trust than a brand name.
  • Problems in living. Mobility, access, and the cost of getting from place to place are everyday problems in living. See solving problems in living.

What open design means for an aircraft

The general idea is described on the open design page of this wiki. For an aircraft, a useful test has four parts:

  • Published plans. Drawings, dimensions, materials lists, and build steps that another person can follow.
  • Open licenses. Terms that say what others may copy, change, and share. Examples seen in projects below include the GNU General Public License for software and the CERN Open Hardware Licence for physical designs.
  • Open tools. Design and analysis software whose source code can be read and changed.
  • Documented tests. Records of what was measured, what failed, and what was fixed.

A design that has all four is rare. Most real projects are partly open. A published plan is not the same as an open license, and an open license is not the same as a safe airframe. Keep those three ideas apart as you read.

The plans-built tradition

Homebuilt aircraft, also called amateur-built aircraft or kit planes, are made by people for whom this is not a profession. They may be built from scratch, from plans, or from kits. Plans-built flying is the closest historical cousin of open design.

  • One overview says Alberto Santos-Dumont published construction drawings of his Demoiselle for free in the June 1910 issue of Popular Mechanics, and that the first aircraft sold as plans rather than as a completed airframe was the Baby Ace in the late 1920s.
  • Bernard Pietenpol built and flew the prototype that became the Air Camper in 1928. The design used spruce and plywood, needed basic woodworking skills, and its plans were first published as a four-part serial in 1932 and 1933. More than 30 different engines have flown in it, and plans were still available in 2015.
  • The Bensen B-8 gyrocopter first flew in 1955. Thousands of sets of plans were sold over about thirty years, and plans for homebuilders were still available as of 2025.
  • Burt Rutan brought the canard layout and moldless composite construction to homebuilders. The first VariEze prototype flew on 21 May 1975 after four months of construction, and the design was then reworked so that it could be sold as plans. About 2000 were under construction by 1980, and the sale of plans ended in 1985.
  • The same overview credits Richard VanGrunsven with taking metal kit construction to a new level in his RV series, and lists the Zenith CH 601 and CH 701 families of two-seat kit planes designed by Chris Heintz among metal homebuilt designs.
  • The Experimental Aircraft Association was founded in 1953. Its founder, Paul Poberezny, wrote magazine articles in the mid-1950s explaining how a person could buy plans and build an airplane at home.

This page has not checked the license terms of each set of plans named above. Sharing plans with builders is a long tradition, but it is not automatically open design in the sense of a license that lets anyone copy and modify.

The one person question

Can one person design and build an aircraft? In a narrow sense, yes. The history above includes designers who flew their own prototypes, and rules in several countries explicitly allow people to build for their own education or recreation. In a wider sense, the honest answer is that one person depends on many others: the authors of open tools, the designers of proven engines and propellers, the owners of test sites, the inspectors, and the community of builders who found the mistakes of earlier aircraft.

It helps to separate four jobs that sound like one:

  • Designing the shape, structure, and systems.
  • Building the parts and assembling them with good workmanship.
  • Testing the finished aircraft, first on the ground and then in the air.
  • Flying it, which needs training, currency, and good judgment.

A single person can do each job, but doing all four, for a new design, with no review, is where the risk piles up. A better model for one person is to build a proven design, document everything, and contribute improvements back to a group.

Rules that shape what one person can build

United States

The regulation for experimental certificates, 14 CFR 21.191(g), covers aircraft the major portion of which has been fabricated and assembled by persons who undertook the project solely for their own education or recreation. The Federal Aviation Administration describes the major portion as more than fifty percent, commonly called the 51 percent rule. Builders must show evidence to the agency, keep a builder log, and fly under operating limitations. The agency page describes a first flight test phase with specific limits, followed by more liberal limits after successful flight testing.

Rules also change. The same section sets dates after which some experimental light-sport certificates are no longer issued, including 22 October 2025 for certain categories.

For the smallest aircraft, 14 CFR Part 103 defines an ultralight vehicle. It must be used by a single occupant for recreation or sport only and carry no airworthiness certificate. An unpowered one must weigh less than 155 pounds. A powered one must weigh less than 254 pounds empty, carry no more than 5 gallons of fuel, not exceed 55 knots at full power in level flight, and have a power-off stall speed of 24 knots or less.

Europe and other countries

Annex I of Regulation (EU) 2018/1139 lists categories of aircraft outside the direct scope of the European regulation, including aircraft, with kits included, where at least 51 percent of the fabrication and assembly tasks are done by an amateur or a non-profit association of amateurs for their own purposes and without a commercial objective. A recital of the regulation explains that home-built aircraft are among those that remain under the regulatory control of the member states. So the details depend on the country.

Ultralight and microlight definitions differ widely. One overview lists a single-seat European limit of 300 kilograms maximum take-off mass for land planes, while the United States uses an empty weight of less than 254 pounds. Whether a flying machine counts as an ultralight depends on where it is registered and flown.

Drones and model aircraft

Uncrewed aircraft have their own rules. The European regulation covers unmanned aircraft regardless of operating mass and calls for registration, and its recitals note that model aircraft flown through clubs have had a good safety record. Check the national rules where you live before flying any model or drone.

Open tools for aircraft design

Each tool below is described only as far as its own project documents say.

  • OpenVSP. A parametric aircraft geometry tool. Its README says predecessors were developed for NASA since the early 1990s, and that it was released as open source in January 2012 under the NASA Open Source Agreement version 1.3. Its site showed release announcements in October 2026.
  • AVL. An aerodynamic and flight dynamics program from Mark Drela and Harold Youngren, using an extended vortex lattice model, with trim and eigenmode analysis. It is released under the GNU General Public License.
  • XFLR5. An analysis tool for airfoils, wings, and planes at low Reynolds numbers, listed on SourceForge under GPL version 3, with the status shown there as abandoned. Its own guidelines say it was written for model sailplanes and strongly disapprove of use for real size aircraft.
  • OpenFOAM. A free, open source computational fluid dynamics toolbox, distributed under the GNU General Public Licence by the OpenFOAM Foundation.
  • SU2. An open source suite for analysis and design optimization of problems governed by partial differential equations, released under the LGPL 2.1 and used in aeronautical work among other fields.
  • OpenAeroStruct. A lightweight tool for aerostructural optimization built on OpenMDAO, coupling a vortex lattice method with a beam model. The repository carries the Apache License 2.0 and says it is provided as is, with no guaranteed support.
  • FreeCAD. An open source parametric 3D modeler that reads and writes open formats such as STEP, IGES, and STL.

These tools can teach aerodynamics and structures very well. They do not replace test data, and the next sections explain why.

Open flight control and drones

Two open autopilot projects dominate this area.

  • ArduPilot describes itself as an open source autopilot system supporting multicopters, helicopters, fixed-wing aircraft, boats, submarines, and rovers. It is licensed under the GNU General Public License version 3.
  • PX4 is an open source autopilot for drones and autonomous vehicles that runs on multirotors, fixed-wing aircraft, VTOL, and more. Its code uses the BSD 3-clause license and it is hosted by the Dronecode Foundation. Its guide lets you run it in simulation with no hardware, and warns that securing a deployment is the responsibility of the integrator.

Simulation is a good low-risk classroom for control ideas. See also open design autonomous vehicle navigation and robotics on this wiki.

Open aircraft projects that exist

Several efforts publish aircraft or aircraft subsystems in the open. Their maturity varies, and a published design is not a flight-tested aircraft.

  • MakerPlane describes itself as a volunteer-driven open source aviation organization focused on avionics and resources for the experimental aviation community, with free open source hardware plans for avionics and software on GitHub.
  • AeroCommons describes itself as a non-profit community advancing open source general aviation. Its listed aircraft project, a four-seat series-hybrid design called MAOS, was shown at the preliminary design phase, along with subsystem repositories for flight control, motors, and landing gear.
  • FreeFlight is a hub started in January 2024 by Robert Osfield for sharing knowledge about light soaring and powered aircraft. Its README adopts open licensing and states that knowledge is shared on the basis that no liability is conferred. Its list of sub-projects is described as examples of what could be hosted.
  • Sky Tribe is a repository describing an open single-seat amphibious electric VTOL aimed at the US Part 103 category, with CAD, a parts list, and research notes under CERN-OHL-S, GPL-3.0, and CC-BY-SA licenses. This page found no flight test record in the material read, so treat it as a design, not a proven aircraft.
  • FVS60 is a repository of design files for a 3D printed 60 inch class flying wing model for slope flying, an example of open sharing at model scale.

Related pages here include open design engine, open design flying car, and open design electronics.

Why a one person effort is hard

A United Consultants UC-1 Twin Bee amphibian at the Winter Haven seaplane base, Florida, photographed in 2007.

Certified aircraft show how much effort sits behind a flying design. The UC-1 Twin Bee, a twin-engine conversion of the Republic Seabee, first flew in 1962 and received its type certificate on 25 June 1965, and only 23 production examples were delivered between 1965 and 1987. Even a small certified conversion took years and a company.

A Dash 8 Q300 of Air Nippon Network, part of All Nippon Airways, photographed in 2009. Registration JA805K.

At the other end, the Dash 8 regional airliner rolled out on 19 April 1983 after more than 3,800 hours of testing on five engines over two years, and first flew on 20 June 1983. The photograph here shows a Q300 variant of that family. One person cannot repeat that scale, and does not need to for a small amateur-built aircraft, but the comparison shows what testing means.

The main difficulties for one person are:

  • Testing. A review of homebuilt safety in the United States by the National Transportation Safety Board, as summarized in one overview, found an accident rate three to four times higher than the rest of general aviation, with almost 10 percent of accidents on the first flight and a further 9 percent on the first flight after a sale. The same overview notes that the stall-resistant VariEze did not show a lower accident rate than other homebuilts, and that comparing accident data is difficult.
  • Engines. Homebuilt engines are most often the same as, or similar to, engines used in certified aircraft, and a minority use converted automobile engines. An engine is a safety system in its own right, and a new engine design takes years of testing.
  • Materials and workmanship. Wood and fabric need common tools and basic woodworking skills. Composite construction offers smooth surfaces and strength, but involves chemicals and has low strength across the fibers.
  • Flight test. The first flights are the highest risk part. A regulator may require limited operating phases for good reason.
  • Insurance and liability. This page cannot settle either. Ask insurers and legal advisers in your country. Note that open licenses and the ArduPilot license text disclaim warranty, so a free design does not shift responsibility away from the builder and pilot.

A practical staged path

A learner who wants to move toward open aircraft can climb in stages. Each stage ends with written records, which is the habit that makes design verifiable.

  1. Study and simulate. Learn the basics, try AVL or OpenVSP on small configurations, and run PX4 in simulation. No aircraft is at risk.
  2. Model aircraft and small drones. Fly under the rules of your country and join a club if one exists. Log every change and every failure.
  3. Join builders. Associations such as the Experimental Aircraft Association list builder resources, workshops, and local chapters. Work beside experienced builders before starting anything with a person on board.
  4. Single-seat ultralight where legal. Check Part 103 or the local equivalent, get proper training, and prefer proven designs.
  5. Larger amateur-built aircraft. Follow the rules for certification, keep the builder log, and use the first flight test phase as intended.

At every stage, publish what you learn so others can check it.

Honest limits

  • Open tools predict, they do not certify. The XFLR5 guidelines say both of its 3D methods tended to underestimate drag in a model sailplane comparison with wind tunnel data, and that it was not made for real size aircraft.
  • An open license does not make a design airworthy. It only describes copying rights.
  • Most open aircraft projects named above are young. Some are design programs with no flight data.
  • Autopilot software needs security hardening, as the PX4 guide points out.
  • Rules vary by country and change. The details above are a snapshot read in October 2026.
  • Accident data for homebuilts is hard to compare, and the figures quoted here come from a secondary overview.
  • This page cannot say whether any specific plan is safe, legal, or suitable for you.

How this connects to this wiki

See also

References

Last checked: October 2026.

Discussion questions

  • What would a fully open aircraft need, beyond published plans, before you would trust it with a passenger?
  • Is a plans-built aircraft from the twentieth century open design, or only open sharing? Where would you draw the line?
  • Which jobs in the design, build, test, and fly chain can one person do well alone, and which need other people?
  • How should a community record failures so that the next builder can learn from them?
  • What is the right balance between freedom to build and the safety of people on the ground?
  • How might lower costs for models and drones change who learns aerodynamics?

Essay ideas

  • Compare the plans-built tradition with open source software, and explain what transfers and what does not.
  • Argue for or against a rule that open aircraft designs must publish test data before a license is granted.
  • Write a staged learning plan for a student with no budget for aircraft, using only simulation and model flying.
  • Explain why a design tool that is accurate for a model glider can mislead when used for a full size aircraft.
  • Ask an AI system to explain the difference between lift, drag, and stability for a beginner, and to suggest three safe simulation exercises.
  • Ask an AI system to compare the licensing ideas behind the GNU General Public License and the CERN Open Hardware Licence for a physical design.
  • Ask an AI system to build a checklist of records a builder should keep to make a project verifiable by others.
  • Ask an AI system to list questions to ask a local aviation authority before building an amateur-built aircraft, without giving legal advice.
  • Ask an AI system to quiz me on the stages of the practical path described on this page.
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