Russian not Luftwaffe

I have checked and checked –

I can now say definitively that this is from a Russian Yak lower wing…..

Now the difficult bit – is it from a Yak 1, 7 or 9 ?

Are there any differences between them ?

Edit – Yak 9

http://mig3.sovietwarplanes.com/yak179/yaks-matvienko/wing.gif

Drawing here

http://mkmagazin.almanacwhf.ru/mkmagazin/avia/yak_9_mk7605_4.gif