airfoiltools.com

Open the Airfoil search page on Airfoil Tools, set your thickness and camber ranges, browse the matching sections with their preview images, then open an airfoil's details page to download its DAT file. This works when you already know roughly how thick and how cambered a section you want; if you only have a name in mind, the A-to-Z index or the category searches (symmetrical, NACA 4/5/6 series) are faster.

Before you start

Airfoil Tools reports a database of 1638 airfoils, and the search page shows your current Reynolds number range (the default is 50,000 to 1,000,000) with a link to change it. That range matters later, because the polar diagrams on each airfoil's details page are plotted for a range of Reynolds numbers — set it to match your application before you compare candidates.

You don't need an account to search or download. The site's pricing signals show no paid tiers or payment platforms, so the search, plotter, comparison, and generator tools are presented as freely usable. Note that "My airfoils" is session-only: anything you add there lives in your browser session and must be re-added after you reopen the browser.

Step 1: Set thickness and camber filters

On the Airfoil search page you filter the database by thickness and camber, and the results come back with preview images of the airfoil sections so you can judge shape before clicking anything.

• Thickness is expressed as a percentage of chord. A 12% section is a common starting point for general work; thinner sections reduce drag but carry less internal volume for a spar.
• Camber is also a percentage of chord. Zero camber means a symmetrical section (good for tails and fins); positive camber generates lift at zero angle of attack.
• Preview images let you reject obviously wrong shapes — a highly cambered, thin section looks very different from a thick, near-symmetrical one at a glance.

If your filter returns nothing, widen one range at a time rather than both. Thickness and camber are independent filters, so a narrow window on each can empty the list even though plenty of sections exist.

Alternative entry points

If filtering by numbers isn't what you need, the site also exposes:

• Symmetrical airfoils — a dedicated list for zero-camber sections.
• NACA 4 digit / 5 digit / 6 series airfoils — grouped by family.
• Airfoils A to Z — an alphabetical index, broken into letter groups with counts (for example, G spans 419 entries, E spans 209, N spans 174). Use this when you know the designation.

Step 2: Open the airfoil details page

Clicking a result takes you to that airfoil's details page. The key thing to check here is the polar diagrams across a range of Reynolds numbers — lift and drag polars. This is where you decide between two candidates that both passed your thickness and camber filter: a section that looks right in cross-section may have a drag rise or a stall characteristic that doesn't suit your Reynolds number.

Match the polar you read to the Reynolds number range you set earlier. A section that behaves well at 1,000,000 may not at 50,000.

Step 3: Download the DAT file

From the airfoil's page you can download the DAT file data in various formats, or feed that same data directly into the site's other tools. The details page also links back to the original data source, which is worth following if you need provenance or a coordinate set the site reformatted.

A DAT file is the standard plain-text container for airfoil coordinates — typically a name line followed by x/y coordinate pairs. Once downloaded, it's the input for the plotter, the comparison tool, or your own CAD and analysis software.

Step 4: Use the DAT file in the other tools

• Airfoil plotter — plots a full-size plan at your chord width. You can adjust camber and thickness, and set pitch to account for wing angle of attack, washout, or wind turbine blade angle. The SVG plan prints full size or tiled across multiple pages for large sections.
• Airfoil comparison — overlays two or more airfoils on one plan for shape comparison, and compares lift and drag polars across Reynolds numbers. Download or print full size for better resolution.
• My airfoils — paste DAT file data into a form to make a custom section available in the tools' drop-down menus. Remember this is session-only.

Step 5: Generate a section if nothing fits

If the search returns nothing close enough, the NACA 4 digit generator (and the 5 digit generator) produces sections directly. Generate, then treat the result like any other airfoil — plot it, compare it, or export the coordinates.

Common snags

• Empty results — your thickness and camber windows are too tight together; loosen one.
• Wrong polars — you're reading a Reynolds number range that doesn't match your application; reset it from the search page.
• Custom airfoil vanished — My airfoils doesn't persist across browser sessions; re-paste the DAT data.
• Print scale wrong — the plotter's SVG prints full size or over multiple pages; check your printer isn't scaling to fit before you cut material.

An airfoil .dat file is a plain-text file that lists the x/y coordinates of an airfoil section, usually with a short header line giving the airfoil's name. You use it by downloading it from an airfoil database or pasting its contents into a tool such as Airfoil Tools, where it becomes the geometry that the plotter, comparison, and polar tools operate on. The format is simple enough to check by eye, which is also why most problems with .dat files are formatting problems rather than software problems.

What an airfoil .dat file contains

A .dat file holds nothing but a name and a set of points. The typical structure is:

• A header line, often the airfoil designation (for example, a NACA number or a named section), sometimes preceded by a comment marker.
• One coordinate pair per line, x first and y second, separated by whitespace.
• Points ordered around the contour, normally starting at the trailing edge, running along the upper surface to the leading edge, then back along the lower surface to the trailing edge.

The coordinates are almost always normalized to a chord of 1, so x runs from 0 at the leading edge to 1 at the trailing edge, and y is the thickness or camber offset at that station. Because the file is just text, you can open it in any editor and confirm the point count and ordering before feeding it to a tool.

Where to get airfoil .dat files

Airfoil Tools indexes a large searchable database — the site states it covers 1638 airfoils — and its airfoil search lets you filter by thickness and camber, with preview images of each section. From a search result you can download the dat file data in various formats, or use that data directly in the site's tools, and each airfoil has a details page with polar diagrams across a range of Reynolds numbers. The site also links back to the original data source for each airfoil, which matters if you need to cite or verify the geometry.

If the section you want does not exist yet, the site provides a NACA 4 digit airfoil generator (and a NACA 5 digit generator) to produce sections, and the search index is also browsable by family — symmetrical airfoils, NACA 4/5/6 series, and an A-to-Z list.

Loading a .dat file into a plotter or comparison tool

Once you have the coordinates, the workflow on Airfoil Tools is:

1. Find the airfoil through the airfoil search, filtering by thickness and camber if you are narrowing down candidates.
2. Open it in the airfoil plotter to view and plot a full-size plan at your chord width. The camber and thickness can be adjusted, and the pitch can be set to account for wing angle of attack, washout, or wind turbine blade angle.
3. Print or export the plan. The output is an SVG (Scalar Vector Graphics) plan that can be printed full size, or split over multiple pages for large sections.
4. Compare sections with the airfoil comparison tool, which plots two or more airfoils on the same plan for shape comparison and can also compare lift and drag polar diagrams across Reynolds numbers. The comparison plan can be downloaded or printed full size for better resolution.

The same dat file data feeds all of these tools, so a section you download for plotting is the same geometry you compare and print.

Adding your own .dat file data

If your airfoil is not in the database, the "My airfoils" feature lets you add it: paste the dat file data into a form and the airfoil becomes available in the tool drop-down menus. Two practical points from the site's own description:

• The airfoils you add are stored only in your browser session, so they need to be added again when the browser is reopened.
• You can source the data from other airfoil databases, or generate the section with a generator tool and paste the result.

This is the route to take when you have measured coordinates, a section from a report, or a custom design that no public database carries.

Common .dat file problems and how to fix them

Because the format is minimal, failures are usually visible in the file itself:

A quick sanity check before using any file: the x values should span roughly 0 to 1, the point count should be consistent with the resolution you expect, and plotting the raw points should trace a closed, smooth contour.

Choosing the right route for your task

• You just need a standard section — search the database, download the dat file, and plot or compare it directly.
• You need a NACA section that is not listed — generate it with the NACA 4 or 5 digit generator and use the result in the tools.
• You have your own coordinates — paste them into "My airfoils" and remember they live only for the browser session.
• You need a physical template — use the plotter's SVG output, printed full size or tiled across pages, rather than trying to reconstruct the shape from a coordinate table by hand.

Airfoil coordinates are the ordered x/y point pairs that define an airfoil section's outline: x runs along the chord and y gives the surface offset, so the same list of points describes both the upper and lower surface of the shape. On Airfoil Tools you can find coordinates by searching a database of 1,638 airfoils, download them as a dat file, or paste your own points into the tools to plot, compare, or generate sections. The main practical limit is that airfoils you add yourself are stored only in your browser session, so they must be re-added after the browser is reopened.

What the coordinates actually describe

A dat file is a plain list of points, normally ordered from the trailing edge along one surface to the leading edge and back along the other. Each line is an x value and a y value. Because the points trace the section outline, they carry the two properties most searches filter on:

• Thickness — the maximum distance between the upper and lower surface, usually expressed as a percentage of chord.
• Camber — the curvature of the mean line between the surfaces, also as a percentage of chord.

A symmetrical section has zero camber, so its upper and lower coordinates mirror each other. Changing chord length scales the coordinates; it does not change the shape.

Finding coordinates in the database

The Airfoil search lets you filter by thickness and camber and shows preview images of the sections, so you can narrow the list before downloading anything. You can also browse by name through the A-to-Z index, which is grouped by first letter (for example, the N entries run from n0009sm to nplx, and the S entries from s1010 to supermarine371ii).

A workable sequence:

1. Set a thickness and camber range that matches your requirement, or search by airfoil name if you already know it.
2. Check the preview image to confirm the shape looks like what you expect.
3. Open the airfoil details page to see polar diagrams across a range of Reynolds numbers.
4. Download the dat file data in the format you need, or use it directly in the tools.
5. Follow the link to the original data source if you need more information about where the section came from.

The site notes a Reynolds number range of 50,000 to 1,000,000, which you can set; that range is the context for the polar data shown on the details pages.

Using coordinates in the tools

Once you have coordinate data, three tools consume it directly:

The plotter output is an SVG plan, which can be printed full size or across multiple pages for large sections. The comparison plan can also be downloaded or printed full size for better resolution.

Adding your own coordinates

If your section is not in the database, use My airfoils: paste the dat file data into the form and the airfoil becomes available in the drop-down menus used by the other tools. This is the route for data from other sources or for sections you generated yourself.

The constraint to plan around: custom airfoils are stored only in your browser session. Close the browser and they are gone, so you need to paste the data again next time. Keep the original dat file somewhere outside the browser so re-adding is a copy-and-paste rather than a re-download.

Choosing between the routes

• Known, standard section — search the database by name, check the preview, download the dat file.
• Section defined by thickness and camber targets — filter the search by those two values, then compare candidates with the comparison tool before committing.
• Section you already have data for — paste it into My airfoils and use it in the plotter or comparison tool.
• Section you want to create from a formula — use the NACA 4 digit or 5 digit generator instead of searching.

Airfoil Tools' plotter generates a full-size SVG plan of an airfoil at your chosen chord width, with adjustable camber, thickness, and pitch, and it can be printed on a single page or tiled across multiple pages for large sections. Use it when you need a 1:1 paper template for cutting ribs, foam cores, or templates, or when you want to compare shapes before committing to a design. You need a browser session and either an airfoil from the site's database (1,638 airfoils listed) or your own coordinate data.

Before you start

• Airfoil source: pick one from the database, or add your own via My airfoils by pasting dat file coordinate data into the form. Note that custom airfoils are stored only in your browser session and must be re-added when the browser is reopened.
• Chord width: decide the actual chord of the section you are building, since the plan is plotted to that width.
• Printer: know your printer's maximum paper size and whether it supports borderless or scaled printing, because tiled output depends on consistent page handling.
• Reynolds number context: the site shows a Reynolds number range (default 50,000 to 1,000,000, adjustable via set). This affects the polar data shown for the airfoil, not the plotted geometry, but set it if you also want to compare performance.

Plotting the airfoil

1. Open the Airfoil plotter application.
2. Select the airfoil you want from the drop-down menus. Airfoils you added under My airfoils appear in these menus during the same browser session.
3. Set the chord width to your target dimension. The plan is plotted full size at this chord.
4. Adjust camber and thickness if you need a modified section rather than the stock shape.
5. Set the pitch to account for wing angle of attack, washout, or wind turbine blade angle. This rotates the section in the plan so the printed template matches the installed orientation.
6. Generate the plan. The output is an SVG (Scalar Vector Graphics) file, which stays sharp at any scale.

Expected result: a full-size plan of the airfoil at your chord, with the camber, thickness, and pitch you specified.

Printing full size

• The SVG plan can be printed full size on a single page if it fits your paper.
• For large sections, print it over multiple pages. The plotter tiles the plan so you can assemble the sheets into a full-size template.
• Print at 100% scale (no "fit to page" or "shrink to fit"), or the chord will come out smaller than specified.
• After printing, measure a known dimension — for example the chord line — against your intended value before cutting anything.

Comparing multiple airfoils

Use Airfoil comparison to plot two or more airfoils on the same plan for shape comparison. The combined plan can be downloaded or printed full size for better resolution. The same tool also compares lift and drag polar diagrams across a range of Reynolds numbers, so you can check both geometry and performance side by side.

Common problems and fixes

Related tools on the same site

• Airfoil search: filter the database by thickness and camber, with preview images, and download dat file data in various formats.
• NACA 4 digit and NACA 5 digit generators: create sections if you don't have coordinate data.
• Reynolds number calc: work out the Reynolds number for your conditions before reading polars.

If your goal is a physical template, the plotter plus multi-page printing covers it. If your goal is shape selection, start with search and comparison, then plot only the finalist.

Use Airfoil Tools' Airfoil comparison application to plot two or more airfoils on the same plan for shape comparison, and to compare lift and drag polar diagrams across a range of Reynolds numbers. The plan can be downloaded or printed full size for better resolution. This works when the airfoils you want to compare are already available in the site's database (1,638 airfoils listed) or have been added to "My airfoils" for the current browser session.

Loading airfoils for comparison

The site tracks how many airfoils you have loaded — the homepage shows a counter such as "You have 0 airfoils loaded." Before comparing, you need to bring the airfoils you care about into that loaded set.

• From the database: Use Airfoil search to find candidates, filtering by thickness and camber, with preview images of the sections. From a result you can open the airfoil details page, which includes polar diagrams for a range of Reynolds numbers.
• From your own data: Use My airfoils to paste DAT file data into a form. The airfoil then appears in the drop-down menus used by the tools. Note that these custom airfoils are only stored in your browser session and must be re-added when the browser is reopened.
• Generated sections: The NACA 4 digit airfoil generator (and a 5 digit generator) can produce sections to compare against database airfoils.

Comparing shapes on one plan

The Airfoil comparison tool plots two or more airfoils on the same plan. This is the core of shape comparison: differences in camber line, thickness distribution, and leading-edge radius become visible when the sections are overlaid at the same chord.

To keep the comparison meaningful, hold the reference conditions constant:

• Chord width — plot all sections at the same chord so thickness and camber differences are not confused with scale.
• Camber and thickness adjustments — the plotter allows these to be adjusted; if you modify one airfoil, apply the same treatment to the others or note the change.
• Pitch — the plotter can set pitch to account for wing angle of attack, wash out, or wind turbine blade angle. Use the same pitch setting across airfoils unless pitch itself is the variable you are studying.

Exporting and printing

The plan can be downloaded or printed full size for better resolution. The plotter produces an SVG (Scalar Vector Graphics) plan that can be printed full size or across multiple pages for large sections — useful when you want to check the overlay at full scale rather than on screen.

Comparing lift and drag polars

Shape similarity does not guarantee similar performance. The comparison tool also lets you compare lift and drag polar diagrams for a range of Reynolds numbers, so you can judge candidates on aerodynamic behavior rather than outline alone.

Practical points:

• The site's default Reynolds number range is shown as 50,000 to 1,000,000, and this can be changed via the "( set )" control. Set the range to match your application before reading the polars.
• Use the Reynolds number calc application if you need to work out the value for your chord and speed.
• Compare polars at the same Reynolds number across airfoils; a polar at Re = 100,000 is not comparable to one at Re = 1,000,000.

Reading the comparison against your design goal

Combine the two views — shape overlay and polars — with the numeric parameters:

If two airfoils look nearly identical on the plan but diverge in the polars, the polar comparison is the deciding evidence. If they perform similarly in the polars but differ in thickness, the thicker section may offer more structural depth for the same aerodynamic result.

Common snags

• Custom airfoils disappear. Airfoils added via "My airfoils" live only in the browser session; reopening the browser clears them. Re-paste the DAT data before starting a new comparison.
• Mismatched Reynolds numbers. Polars are only comparable at the same Re — check the range setting before drawing conclusions.
• Scale confusion on the plan. If airfoils are plotted at different chords, thickness differences are exaggerated or hidden. Match chord first.
• Screen resolution limits. For fine differences in leading-edge shape, download or print the plan full size rather than judging from the on-screen plot.