The question: Is there a way to figure out if an increase in wingspan is likely to decrease the drag of a particular design, and at what altitude that might happen?
The background: The Vision design can be built in two versions: a shorter-wing "SP" and a longer wing "XP". The designer, Steve Rahm, noted that the SP would be faster at lower altitudes, but that the XP would be faster at higher altitudes. I don't know the reasons, my guess would be that in denser air the decreased wetted area/form drag of the short wing would win out, but at higher altitudes the increased AoA needed by this shorter wing would result in higher induced drag than the long-wing version would have.
Would a design like the Sonex or even an RV have less drag in cruise flight at altitude (say 10K ft) if the wing were a few feet longer (same chord, still no taper, but higher AR due to longer wing)?
Opinions are solicited!
The background: The Vision design can be built in two versions: a shorter-wing "SP" and a longer wing "XP". The designer, Steve Rahm, noted that the SP would be faster at lower altitudes, but that the XP would be faster at higher altitudes. I don't know the reasons, my guess would be that in denser air the decreased wetted area/form drag of the short wing would win out, but at higher altitudes the increased AoA needed by this shorter wing would result in higher induced drag than the long-wing version would have.
Would a design like the Sonex or even an RV have less drag in cruise flight at altitude (say 10K ft) if the wing were a few feet longer (same chord, still no taper, but higher AR due to longer wing)?
Opinions are solicited!
