Patriotic Socks (Stars on calf), Schuss-Plus yarn, medium size adult  (adjust pattern accordingly), 60 needle cylinder, no ribbing

Use either a hem-top of 15 rounds in BLUE or a straight-up selvege hanging round one on round two.  Continue for four more rounds raising all needles after passing the beginning needle at the right side hash mark.  (You need to do this every time you start or end the stars.) 

"Stars": push down every other pair of needles ahead of the yarn carrier starting at the hash mark.  With WHITE yarn go around the cylinder twice, raising the needles up out of work after the hash mark on the second round.  Bring yarn carrier to front again and switch back to BLUE.  Knit three rounds ending with all needles raised.  Repeat star pattern in WHITE.  I offset these so that the opposite pairs will be white on the middle row of stars.   Knit three rounds in BLUE.  Repeat star pattern in WHITE using the same pairs as for the first set.  Knit four rounds in BLUE.

About ten needles before the side hash mark, terminate blue yarn with 2" tail and attach RED.  Knit two together to graft.  (Repeat all remaining grafts in this same way.)  On the row after the first graft, pick up the tail and knit it in with whatever color you are using so you don't have ends to work in when you are finished.  These grafts will not come apart.

Knit six rounds in the red, six white, six red, six white, six red.  After the next stripe of six white, continue with heel formation.  At final row taking needles out of work, graft into red yarn again.  finish heel.  Continue with six red, six white, six red, six white, six red, six white, six red finishing in the center front and grafting on white to do the toe.

Kitchener toes closed.  Work in yarn ends of white stars on back of sock.  Blue yarns can be worked back on the outside of the sock as usual.  Wash 5 minutes in washer to full the wool and block on sock stretchers for a perfect finish.

A slotted yarn carrier enables you to make the star rows without cutting your blue yarn which saves lots of handwork.  Let your blue yarn dangle down the center from your topper with a clothespin to hold it in place.  Your white yarn will wind around it once or twice, but it will still knit okay.  Cut the white yarn after each row of stars and simply re-thread the blue.

You may want to make each stripe 7 or 8 rounds to enlarge, make more rows of stars, or add an additional set of stripes.  However, knitting the sock as above will give you 7 red stripes and six white ones plus a white toe.  That's about as close to a real "flag" as you can get, though it has 45 stars.