FWIW - I took the following measurements of tapered (conical) tubing from my horns:
Trumpet: Leadpipe - 8-1/2" + Bell - 22" = 30-1/2"
Cornet: Leadpipe - 13-1/4" + Bell - 21" = 34-1/4"
Flugelhorn: Bell - 39-3/4"
The proportion of conical to cylindrical tubing is different among the three horns. It also appears that the distinct disparity among the leadpipe taper lengths (or lack of taper whatsoever) in relation to the various lengths of bell taper contribute to the differing timbres of the instruments.