You can spell anything any way that you want, but if you want someone else to understand what you are trying to say, it helps to spell correctly. You may also insult someone by incorrect spelling. Foker was a Dutch company -- they didn't build any "Wulf" types at all. During WWII, the Dutch were conquered, starved & generally brutallized by the Germans & they don't appreciate anyone suggesting that they contributed to their own downfall by building combat planes for Germany.

Focke Wulf was the German company that built the FW 190 (among other things).