My conclusion is in capitals at the bottom.
From web source:
"The parachute types specified by D.B. Cooper, according to author Gunther, were acquired from a sport parachute center in Issaquah, Washington-two standard emergency back-type and two chest-type auxiliary parachutes (the latter generally termed reserve chutes, for back-up emergency use if the main chute should malfunction when a sport parachutist was making a jump). The parachute center in Issaquah provided the two chest packs and Earl Cossey, a parachuting instructor at the Issaquah drop zone as well as an FAA Master Parachute Rigger, contacted at his nearby home, brought two back-type rigs from his parachute workshop there and delivered them to the parachute school."
Other sources indicate that military parachutes were first delivered, then refused by Cooper who asked for sport parachutes. Supposedly he even specified the name of a parachute school where they could get them. Unclear if this is true. Maybe the refused military chutes were just repacked in new rigs so they didn't automatically deploy. Cooper supposedly wanted a ripcord.
In any case, now the FBI has revealed that the main parachute, at least, was a "Navy NB6" or "Navy Backpack 6". This is the wrong acronym.
NB-6 is the correct acronym.
The FBI have said Cooper jumped with a chute with a 26 ft canopy. The NB-6 has a 26 foot conical canopy. It is easily identified because of 22 gores/lines. (which give it the conical shape)
The FBI has not said anything about the reserve chutes. It would be typical for the reserve chute to be like a T-7 or T-10. T-7's were 24 ft canopies.
While dated 1946 would imply the found canopy was old, it's possible a 1946 canopy was still being used as a reserve chute in the '70s.
Interestingly Cossey says that one of the reserve chutes was marked X because it was sewn shut as a classroom training aid. It probably had a real chute in it. It probably was an old chute.
So the found chute could have been Cooper's "sewn shut" reserve chute.
They'll quickly be able to say it wasn't the 26 ft NB-6 canopy. The 24 ft nylon canopies were quite common in 1946.
That 1946 parachute is likely a 42G2001, 24' canopy, made of nylon.
see:
http://books.google.com/books?id=BK...nAr1S2n&sig=5PscLGmKPBSjRJAoCKY2ykA8Ow0&hl=en
also see:
http://books.google.com/books?id=yd...IcxKeGl&sig=k5J63jZrHUlgC7UtygqDCnl8CgA&hl=en
the 42G2001 was the drawing number for the 24' canopy, in a number of backpack parachute assemblies from the time period. There was a 28' canopy also, but 24' was more common.
detailed specs on NB-6 are here
http://books.google.com/books?id=BKTuTXrXQu0C&pg=PA245&lpg=PA245&dq=%22nb+6%22+canopy&source=web&ots=n_mnAr7M4m&sig=IVVzc847PilsMBckDYH32xIAyjw&hl=en
note the NB-6 assembly has a 26' canopy as FBI says, but it has 22 gores. Makes it easy to identify. (22 lines)
The 26' canopy was conical rather than flat, because of the removal of the 4 gores.
AAF regulation 65-35 dated Aug 10, 1943 required all AAF canopies to be stamped with the fiscal year and a serial number. Which is why there is a date and serial number on the found canopy.
Apparently many of the canopies were made by a company called Pioneer Parachute Company or maybe Joe Smith Parachute Co.
Here's details on the NB-6 parachute system (page 176)
http://books.google.com/books?id=BK...rch_r&cad=1_1&sig=XgP4copzFp_5vR3tNv2IL8ChmZA
Interestingly, the FBI Agent Carr has shown in a recent video that the parachute left behind with cut strings, had a red canopy. (I believe it was the 2nd, functional reserve, that he cut the strings on)
Evidently they believe the canopy of the main one he jumped with (the NB-6) was white. But they've not said anything about the color of the reserve chute he jumped with.
WHY: BECAUSE IT WAS SEWN SHUT. PROBABLY NO ONE KNOWS THE COLOR OF THE RESERVE CHUTE HE JUMPED WITH, IT'S SIZE, OR ANYTHING ABOUT IT!
There are some mistaken web pages that say the main chute he jumped with was the "marked X" "training" "sewn shut"
canopy. But it seems clear that Earl Cossey said it was a reserve, and not the reserve that was left behind. i.e. the one
Cooper jumped with.