It looks like FAR 61.69 and 91.309 as of 1 Sep 04 have now added the
words "unpowered ultralight vehicle", which in FAR 103 are hang gliders.

I don't know how this pertains to a Sparrowhawk, but if an FBO can tow
gliders heavier than a Sparrowhawk, and lighter than a Sparrowhawk, then
they ought to be to tow an actual Sparrowhawk.

I also read that in denying exemption 6024 in 1995 the FAA explicitly
said that certificated aircraft were the preferred tow vehicles for
unpowered ultralight vehicles, but I haven't been able to find that
statement using Google.

Ken (who did several auto payout winch tows at New Jerusalem on Sunday)
San Jose, CA