Preheat oven to 350°F.
Sift flour, salt, cream of tartar and Splenda together.
In a separate bowl, beat egg whites, water, and vanilla until soft peaks form.
Gently fold dry ingredients into whipped egg whites. Fold until just incorporated.
Carefully pour batter into an un-greased 10 inch tube pan.
Bake for 35 to 40 minutes.
