rise quickly. During this condition, it creates tremendous turbulence, and is very dangerous. During "thermals" the balloonist cannot control the balloon.

How does a pilot land a balloon?The pilot controls the balloon's descent by opening small vents near the top of the balloon and occasionally giving the burner a blast to keep the descent slow and gradual. As the air inside the envelop cools, the balloon descends. The pilot may drop a safety line for crew members to slow down the lateral movement of the balloon and "walk" it to a safe landing area. Upon landing the balloon is deflated by pulling a valve line which opens the parachute valve atop the balloon. The hot air escapes rapidly.

What does it take to become a licensed balloon pilot?A licensed pilotRepublican candidates have rolled out formal tax plans, but only seven had enough details for the Tax Foundation to model, said foundation president Scott Hodge. (The others belong to Ohio Gov. John Kasich and former Arkansas Gov. Mike Huckabee .)

As the field narrows, the plans could become more substantive or disappear into the ether.

"The interesting question is when we boil down to fewer candidates whether candidates will refine their plans further," said Williams, of the Tax Policy Center. "Some have lots of detail already. But others, particularly Carson, have only dim outlines and some — (Carly) Fiorina, (Lindsey) Graham — have offered nothing beyond the broadest of platitudes."

Williams and Thorndike, the tax historian, both see a divide between the mainstream plans that retain most of the current tax