Hmmm,
I have repaired maybe 15 broken booms including 3 that I have cardinal
knowledge of and it is my humble opinion that the tail wheel dragging
sideways has little to do with snapping the boom. In all 3 of my
personal recollections, the tail was off the ground during the event
(2 had wheels, 1 had a skid). I watched a Discus come as close as it
could to breaking its boom when it landed beside me, only a bit deeper
into the barley field at Camby, Ca The left wing tip caught a clump of
barley and around it came, tail off the ground, spun 180, T-tail laid
over a good 30 degrees, then the boom came down and she just sat there
and shook for a moment. What determines weather you break the boom or
not is speed, ground loop below 40 knots and you will probably come
out unscathed, do it above 40 and she's likely to break (Libells
reduce by 10 knots). What's really going on is simply this, The wing
can take it quite well because it has a spar, the boom doesn't and
one side goes into compression while the other is held in tension,
compression looses and buckles inward, do it hard enough (speed) and
she snaps off, tail wheel had very little to do with it.
As always, just my humble opinion,
JJ