Which part of a straight wing stalls first
 

Hey guys
I have come arcoss with the stalling of a st. Wing
.i have read in my textbook that st wing stalls at root first. Is it because the spanwise flow of the st wing flows towards to the root which gives rise to the above phenomenon?!

Also for the sweptback wing, as for the tips stall can I explain it as " the accumulation of spanwise flow at the tips has given rise to a lower energy boundary layer over the tip, and therefore stalls first before the root"

Thanks guys!

The inboard part, because of "washout": the wing is twisted so the tips have less AoA; they therefore stall last. It means as you start stalling, you retain roll control. This also feature also occurs on swept wings. Also, on a swept wing, if the tips stalled first, you'd get a pitchup (centre of lift effectively moved forward) which would completely ruin your day!

Do your own coursework! :p

OK, some things to think about:

Look at what the spanwise flow does for the local flow direction, the local effective chord and this the local effective Re - it all flows [sic] from that.

With the swept wing it's more involved because the upper surface spanwise flow component towards the root is opposed by the spanwise component of airspeed. This produces a stagnation point somewhere along the span which is where the stall will commence. Precisely where this point isn't very well defined, so swept wings are prone to dangerously asymmetric stalls - most of the early swept jets were known for nasty low-speed wing-dropping tendencies. The cures for this involved trying to nail the stagnation point to a location - saw/dogtooth leading edges, notches, LE camber-changes etc.

Funny stuff happens with spanwise pressure distributions on swept wings, especially if the AR isn't small. Follow those thoughts to their conclusions and you find the reason for Horten's "bat-tail" feature and the unswept centre-section TE on many/most large jet transports.

€0.12 supplied,

PDR

Phew!
Thanks for that, PDR.
So that's where I went wrong, eh?
I hadn't given much thought to how a dog-tooth and bat-tail might have helped on a Traumahawk.
Anyway, as it turned out, the aircraft was usable again.
Respect, bro.