How to Select an Airfoil for Electric Aircraft and eVTOL Applications

The energy budget changes the weighting

A battery carries far less energy per kilogram than fuel, and it does not get lighter as you fly. Profile drag and induced drag are paid for the whole mission out of a fixed energy store. For a wing-borne electric aircraft the section question is still the airplane question: L/D of the aircraft at the cruise CL, of which the section L/D is one piece, plus a stall margin for landing when you cannot go around forever. Chasing a tiny clean-section drag gain that costs spar depth, and therefore wing weight, and therefore induced drag, is a good way to lose range.

Compute the Reynolds number from the real chord and the real cruise speed. Many training and light electric aircraft sit at modest Re compared with a turboprop of the same drawing. Many small eVTOL lifting surfaces sit lower still. Use that Re. A section selected at transport-aircraft Reynolds number is a different object.

Three aerodynamic jobs on an eVTOL

Noise and the neighbour

eVTOL sections and rotor blades are chosen in public. Tip speed, blade loading, trailing-edge thickness and whether the blade is separated in climb all show up in noise. A quiet rotor is mostly a slower tip and a careful planform. The airfoil still has to support that operating point with an attached boundary layer and a thin trailing edge. Quote noise from an acoustic calculation or a test. Quote the section from its polar. Keep the two sentences separate so a low CD is not mistaken for a certificate of quiet.

A practical short list

• Freeze cruise CL, Re and Mach for the wing. Freeze local Re and Mach for the rotor stations. They are different sheets of paper.
• Demand a thickness the structure can use. Electric wings still have spars; electric rotors still have to hold a blade.
• Score clean and tripped polars. Urban operations are dirty, wet and full of insects.
• Score CM. Distributed propulsion does not delete trim, and a canard or a tandem wing has its own moment balance.
• For the rotor, look at the high-Re tip and the low-Re root separately, and look at trailing-edge thickness on purpose.
• Leave transition-flight loads as a labelled gap unless you have a method that covers them.

HENFOIL is the section screen for that short list: geometry, VIC polars, compare, and a record of Re, Mach and transition. The vehicle energy model and the acoustic model sit downstream of those polars and should cite them.

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Where this sits in the series

In simple words: what this page is for

Battery energy makes cruise L/D expensive to waste. eVTOL adds a second problem: sections and rotors that must behave in hover, in transition and in wing-borne flight.

This lesson exists because section decisions fail when geometry, method labels and selection reasons are scattered. How to Select an Airfoil for Electric Aircraft and eVTOL Applications helps you keep a clean trail from shape to polar to choice.

Why the topic matters

Engineers lose time when a title sounds clear but the page only sketches the idea. This article expands How to Select an Airfoil for Electric Aircraft and eVTOL Applications so you can answer three questions without jargon: what is the idea, when do you use it, and how do you check it in a HENDOI product.

Read the sections above for the core definitions. Use the steps below to move from reading into a real project trail you can share with a teammate.

How to apply this in HENDOI

In practice: create a HENDOI account or log in, open HENFOIL, bring a section in (create, import DAT, or digitize), pass the geometry gate, climb the analysis ladder only as far as the decision needs, then compare and archive. Every calculated number should keep its method label.

When the section choice is ready for the aircraft, continue in HENSYNTH for mission, compliance and trades. Same account. Same plans.

What this page will not claim: a teaching polar or geometry note is not a flight-Re certificate. HENFOIL labels methods so you know what you bought. Tunnel data and professional judgement still sit outside any single software run.

Checklist before you leave this page

• Can you state the idea of How to Select an Airfoil for Electric Aircraft and eVTOL Applications in one sentence?
• Do you know which product owns the next action — HENFOIL or HENSYNTH?
• Will every number you keep carry a method label or a stored-run source?
• If you are new here, have you opened Register or Login?

Related reading on this site

• HENSYNTH range and endurance screening for electric cruise
• HENSYNTH electric UAV mission screening loop
• How to Evaluate Airfoils for Small Electric Propeller Aircraft
• All HENDOI blog articles
• HENFOIL product page
• HENSYNTH product page
• Pricing — Student, Professional & Team
• FAQ
• Login · Register now

• Previous: Airfoil selection for wind turbine blades
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• Index: all HENFOIL airfoil lessons

These pages teach the ideas. They are not wind-tunnel data and not a certification analysis. When a number matters, compute it at a stated Reynolds number, Mach number and transition setting, and keep the method label on the result. In HENFOIL that production polar is a VIC polar — see the analysis ladder and the polar field guide.