The Fleegle heel is a bit different from a straight-up flap. Instead of having the "eating line" go straight up the heel to create a rectangular flap, the "eating line" goes on a diagonal. As a result, it's harder to do reinforcement sts on this type of heel. It also fits a little differently - it's more elastic because of that diagonal line.
I present here a slightly modified Fleegle, which incorporates a lot of the standard toe-up-flap recipe I presented a while back...
1. knit sock to gusset line on your template
2. start increasing for gussets, 2 sts every other row. The traditional gusset increases are on either side of the sole. I usually do:
R1: K1, KTBL, K to 2nd last st on sole, KTBL, K1
While you are doing this, continue the instep sts in pattern.
Alternate R1 and R2 until you reach the "flap line". For fingering-weight socks, I usually find I increase about 14 sts, give or take a couple, on each side for my own feet (ladies' medium). Don't sweat this too much - socks are elastic.
3. when you reach the flap line, stop increasing. Now, knit to the center of your sole stitches and place a marker.
4. You are going to knit a little wedge around that center stitch, to round out the back of the heel. This you do as follows:
R1: K to center marker, K4, wrap and turn (or do whatever hole-hiding technique is your current fave)
R2: P to 4 beyond center marker, wrap and turn
R3: K to 8 beyond center marker, dealing with that wrap (or whatever) as you knit over it, wrap and turn.
R4: P to 8 beyond center marker, dealing with the wrap you encounter, wrap and turn.
R5: K to 12 beyond center marker, dealing with wrap, wrap and turn.
R6: P to 12 beyond center marker, deal with wrap, wrap and turn.
Knit across the sole and then across the front of the sock, maintaining any pattern on the front as set.
You've now added 6 rows (which works out to about 1/2" with fingering weight yarn) to the back of the sock. If you're knitting with sport or DK yarn, you'll have to adjust this because 6 rows will probably be too much, and make the sock too long. So do fewer short-rows. When you slip the template into the sock, the sock should not extend longer than the template.
Recognize these instructions? Up to this point, the construction has been identical to the "traditional" toe-up flap heel I blogged about here. And again, now you are going to consume the gusset stitches in turning the heel...but in a slightly different manner.
5. R1: K to 1 past the center marker, taking care to deal with that last wrap&turn (or whatever hole-hiding thing you did) on the way. SSK, K1. Turn. (note: DO NOT WRAP or bother with hiding holes).
R2: sl 1 pw wyif, P to 1 past the center marker, P2tog, p1. Turn. (again: do not wrap or anything. Just turn.) At this point, you can lose the marker - you won't need it anymore.
R3: sl 1 kw wyib, knit to 1 st before gap, SSK the next two stitches (bridge the gap), K1 and turn.
R4: sl 1 pw wyif, purl to 1 st before gap, P2tog the next two stitches (bridge the gap), P1 and turn.
Repeat R3 and R4 until you hit the sides of the sock, and the number of sts you have left is equal to the number of sts on the instep side.
You are done. Those extra stitches that you knit/purl after the ssk/p2tog ensure that the decrease line forms a diagonal.
As you start knitting all around the sock again, you might find you need to close holes at the sides of the heel. Do this by picking up an extra stitch from the front of the sock (I usually pick up the arm of a stitch from 1 row lower down) and knit it together with the stitch from the heel side.
Note: You can make a more traditional Fleegle heel by continuing with step 2 (gusset increases) until you get to 1/4" before the end of the template (ie. 1/2" beyond my flap line). Place marker as per step 3, skip step 4 and go straight to step 5. You will have more stitches to decrease, and hence you will end up with a higher flap. Personally, I do not like the fit of this heel as I find the flap too high.
[completed Fleegle heel]