B-70 SAC

[MKSheppard]

Okay guys; here's the information on the planned PRODUCTION model B-70A Valkyrie.

See; there were to be three aircraft built originally for the program, plus production models.

Air Vehicle #1; whi ;Dch became the XB-70A.
Air Vehicle #2; which became the XB-70B.
Air Vehicle #3; which was to be the YB-70, and would carry a sort of early bomb nav system and have a four man crew -- basically to test out the early prototypes of the radar etc and to do bomb drop tests.

However, A/V 3 was cancelled, and errors in the construction of air vehicle #1, caused one of the fuel tanks to be permanently sealed off (it leaked like crazy); and a speed/altitude limit to be imposed (due to it using early production honeycomb skin); meaning it was restricted from sustained Mach 3 flight (it could hit it for short bursts), due to skin problems.

A/V #2, being built later in the program, benefited from the mistakes made in A/V #1's construction, and was significantly better performing due to the problems with the stainless steel honeycomb construction being corrected. It proved that the B-70 as designed could cruise indefinitely at Mach 3 as long as it had fuel by doing a 30 minute flight at Mach 3 (which was when the engineers calculated maximum skin expansion and heating would occur). However, before we could fully explore the envelope of Mach 3 flight, A/V #2 was lost in a mid-air collision.

A/V#1 went on to do some research for NASA before being flown to the USAF Museum.

So. Enough talking. Here's the Statistics for the XB-70A, which you see most commonly quoted (the specs are from Baugher).

Maximum speed 1982 mph at 75,550 feet, 1254 mph at 35,000 feet. Landing speed 184 mph.
Service ceiling 75, 500 feet. Initial climb rate 27,450 feet per minute.
Combat range 3419 miles, maximum range 4290 miles.
Dimensions: Wingspan 105 feet, Length 196 feet 6 inches, Height 30 feet 8 inches, wing area 6297.15 square feet.
Weights: Empty weight 231,215 pounds, 521,056 pounds gross weight, 534,792 pounds maximum.

You can compare them with the B-70A model shown here.

EDIT: By the way, don't be disturbed by the 10,000 lb load for the "Design mission". That's a common "special weapons" load for nuclear armed aircraft; the B-52's "design mission load" is also 10,000 lbs.

B-70 SAC Page 1
B-70 SAC Page 2
B-70 SAC Page 3
B-70 SAC Page 4
B-70 SAC Page 5
B-70 SAC Page 6
B-70 SAC Page 7

[Sidewinder]

To reflect change from J93-GE-5 engines to J93-GE-3 engines. Air vehicle performance data are predicated on the J93-GE-5 engines. However, installation of the J93-GE-3 engines and the associated weight and fuel capacity changes will result in less than 1% variation from the quoted performance.

The engine ratings for the -3 is lower than those of what I presume to be the -5, as listed on page 03. Why were less powerful engines to be used on production models of the B-70? GE encountered technical difficulties in developing the -5? Cost?