I have just received the following information by
e-mail from Joshua about the WW2 US T-5 and
T-7 parachute and harness, and because I feel that it is so informative. I have
posted it here on this page to hopefully help my fellow modellers. Plus, I would
like to thank Joshua for taking the time to share this detailed information with
I have studied the T-5/T-7 parachute for years
and just thought I would give you a little information. The belly band isn't
there to support weight. It's purpose was for keeping the reserve from flapping
around, and also worked great to secure equipment. Its attaching seams will not
hold very much weight-its sewn with the regular parachute pack thread, about 8
lb. tensile strength. The two reserve hooks/d-rings are plenty strong. They were
rated at 5000 pounds. (the original ones were the reg. harness hooks, rated at
2500, but by D-day just about all were the 5000 type).
The hooks will go 8420 pounds to the maximum
bend. That's when the hooks would bend far enough for them to come off the ring.
The rings have a much high bending strength. That means it can safely take an
opening shock of 10,000 lbs, or approx 40 opening g's (at about 40 g's your
probably dead). Even in the worst conditions- the reserve opening at 250 feet,
300 lb weight, 1.5 second inflation time, and at terminal velocity the opening
shock would only be about 2400 lbs. Normal opening shock would be in the
vicinity of 1300 lbs for the reserve, and that's probably a slightly high
number. Some troopers on combat jumps cut off the belly band to be able to shed
the harness faster.
Also, when the reserve opens, it doesn't
suspend the jumper at that much of an angle. Though he isn't suspended
vertically like when the main is open, he is still close to vertical, though it
isn't very comfortable. This is especially true when there is a heavy load of
combat equipment; it pulls the jumper slightly more vertical with all the weight
at the bottom. Hope this helps.
Realize though that the opening shock forces have so many variables, so the
numbers are not extremely accurate.