My design has full-span flaperons and one of the drawbacks is a very low maximum drag in landing configuration. Because of that I've always seen some kind of drag brakes unavoidable, especially since my induced drag won't be very high during landing. My design has a CS prop, but I don't want to rely on that for decent landing qualities... because you need them most when the engine quits.
So, what is a desirable L/D in landing configuration at for example 1.3 times stall speed, ignoring engine influences?
I've tried to find some hard data on this, but I can't find much more than this, which only shows an unflapped L/D of 12.8. On gliders there is some hard data though. The (old) Duo Discus has an L/D with full drag brakes of 1:9.9 and indeed approaches far too shallow. The Club Libelle on the other hand does around 1:3, which makes for a slam-dunk approach that would make the average chopper pilot jealous.
So it's clear that for a "Cessna-like" landing I need to be somewhere between 3 and 10. But where?
So, what is a desirable L/D in landing configuration at for example 1.3 times stall speed, ignoring engine influences?
I've tried to find some hard data on this, but I can't find much more than this, which only shows an unflapped L/D of 12.8. On gliders there is some hard data though. The (old) Duo Discus has an L/D with full drag brakes of 1:9.9 and indeed approaches far too shallow. The Club Libelle on the other hand does around 1:3, which makes for a slam-dunk approach that would make the average chopper pilot jealous.
So it's clear that for a "Cessna-like" landing I need to be somewhere between 3 and 10. But where?
