Real polars, side by side
26 configurations across 16 types, every one transcribed from a flight manual or a published flight test, and every one carrying the wing loading its numbers apply at. That last part is why most polar comparisons on the internet are meaningless.
Overlay
Solid inside each source's data range, dashed outside it. Filled dots are the source's own tabulated points where it published them; the open ring is the speed to fly at the settings below.
The numbers
| Glider | W/S | Best glide | at | Min sink | Speed to fly | Source |
|---|---|---|---|---|---|---|
Where the curve and its own source disagree
- : the fitted curve gives where the document prints ().
The curve is built from each source's minimum sink and best-glide speed, which leaves its printed glide ratio as an independent check. A few percent of disagreement is normal and is the manufacturer's own arithmetic, not ours.
Pick up to three
of configurations. Several types appear more than once because a polar is only meaningful at a stated wing loading.
What this assumes, and what it can't know
Almost all of these are calculated, not measured. Manufacturers publish polars derived from their own aerodynamic work, and this library contains one pair that shows what that is worth: the Grob G103 Twin II reads 37.0 in the factory manual and 33 in Richard Johnson's flight test, at wing loadings half a kilogram per square metre apart. The factory is optimistic by 12% — larger than the difference between many of the aircraft here. Every curve is labelled with which kind of source it came from, and the page warns you when you mix them.
Every curve is a quadratic fitted to two points, and the fit range says so. Each is built from the source's own minimum sink and best-glide speed, which reproduces those figures exactly and leaves the printed glide ratio as a check. Outside the range between them the curve is dashed and it is extrapolation — which includes every speed-to-fly answer, because speed to fly is always faster than best glide. Fitting instead through the tabulated tables that four of these types publish was tried and was worse: one parabola cannot describe a glider from 62 to 180 km/h, and the attempt threw the minimum-sink speed out by up to 23 km/h. Where a source publishes a table, its points are plotted so you can see the departure for yourself.
A wing loading without which none of this means anything. Every entry carries the loading its figures apply at, and several types appear more than once for that reason. A comparison between two polars at different wing loadings is not a comparison between two aircraft. Types whose source omitted the reference loading were left out rather than guessed — the SZD-50-3 Puchacz has a complete, cross-validated speed table in two languages and is absent for exactly this reason.
This library holds no airworthiness or operating limits — no never-exceed speed, no manoeuvring speed, no maximum mass, no placarded anything. That is deliberate and it is enforced by the loader rather than by memory. Those numbers are specific to your airframe and its modification state, and they belong on your placard and in your flight manual.
Not yet reviewed by anyone but us. If you run a club's books and one of these assumptions is wrong, we would genuinely rather hear it than not — tell us and we'll credit you here. This is a budgeting estimate, not a quote. Every club sets its own rates and they change; check with the club before relying on a number.
Your aircraft is not here
Thirteen types is a library, not a database, and it will stay that way — every entry costs an afternoon of finding a manual and checking it. The interactive polar takes your own figures instead, and tells you whether they are self-consistent.