In article ,
says...
Will the landing area be at the Pepperell DZ? If so, how much alt.
AGL do you expect out of an 8mi straight climb? ...Or will the plane
still be able to fly a pattern to get some alt before jumprun?

With a 15 minute flight as specified and a rate of climb of 500-750 feet
per minute, that should get you reasonably high.

http://www.dropzone.com/columns/B17atQuincy.shtml

I got that RoC off the net, and though one wouldn't expect a 60 year old
bomber to have as good a performance as a new bird, it's also not carrying
a full load of bombs, fuel, machineguns and other gear needed for a long
mission over Germany.

You could always plug in the aircraft, the airfield and the DZ into Flight
Stimulator and see for yourself...