Contra Gravity ??

With the change in traveller of gravity = contra gravity, how effective
would these 'fusion' rockets be in atmosphere. I'm not a science type person
or anything, but wouldn't air resistance and stuff like that cut into
speed ????

Does this mean we will see combination prop/contra gravity vehicles ???

In H. Beam Pipers novels (where I assume de old contra grav thing
came from), what did he use as the 'thruster' units on vehicles he
described.

Also, doesn't the 'grav hours' thing seem a bit limited ?? Actually, since
I havn't got the book, what is the average number of 'manuever hours' the
traveller vehicles have now ????

I can remember (murkily) that in 4 day planet (Piper), a submarine/space
craft could go about a week or something like that . . . . .

Michael (C/O Sean Maguire)