What’s the speed for lowest sink rate on a DA20? In the DA20, the POH lists for glide speed (flaps up) only one speed giving the best glide angle / furthest distance (73 KIAS).

But what about, if I don’t need that much distance to glide (e.g. because I’m high above an airport) and rather want to optimize for the maximum time airborne, i.e. the lowest sink rate. Which speed would I need to fly for that? I couldn’t find any L/D diagram in the POH either where I could find it from.
Admittedly, my prop performance theory is a tad rusty, so maybe someone else can provide proof here.

I seem to recall that - assuming a quadratic drag polar which might not hold true for your aircraft - minimum sink speed has a theoretical value of .76 x best glide speed, so in your case that would be around 56 KIAS.

If you’re comfortable and consider it safe to do so, why don’t you (at a safe training altitude) trim for 73 KIAS and establish a stable idle descent, note vertical speed descending through a predetermined altitude, reposition to initial altitude and repeat in maybe 5kts decrements down to stall speed or some safe margin above - the former of course only if flying right down to stall is still trained and allowed in small aircraft. This will give you at least a rough idea of where minimum sink speed lies and what rates to expect.

The DA 20 Approved Flight Manual doesn’t help much, by the way.