Delta

The Delta launch vehicle has been continually upgraded through the years in response to the need for increased payload capability. The most advanced Delta configuration preceding Delta II was the Delta 3920/PAM which had a 100% success rate. This design was upgraded in two phases to provide Delta II performance capabilities: Delta II 6925, with a 14% increase in geosynchronous transfer orbit (GTO) capability, and Delta II 7925, with a further 26% increase.

Delta 2914 - The model DSV-2W was produced by McDonnell Douglas as the first stage of a Model 2000 series Straight Eight Delta Launch Vehicle. The "Straight Eight" designation referred to the vehicle's constant 8-foot diameter from base to nose curvature. The Straight Eight vehicle provided a much expanded spacecraft fairing envelope and a sizeable increase in payload weight, utilizing previously flight-proven components. With versions developed for both two- and three-stage requirements, it offered choice of vehicle for each specific mission, placing spacecraft into low earth orbits, by either a direct ascent single-burn or Hohmann transfer dual-burn flight mode.

The three-stage configuration was suited for missions that placed spacecraft into highly elliptical earth orbits or for high-energy missions involving synchronous satellites. The Straight Eight launch vehicle was first used on 9 November 1973 by NASA to launch Telesat, Canada's Anik-l TV-telephone relay satellite. The DSV-2W first stage included a repackaged Rocketdyne H-l single-start, liquid bipropellant main engine, designated a Model RS-27, two vernier engines, and the attach fittings for either three, six, or nine Castor II strap-on solid propellant motors. The interstage assembly extended from the top of the first stage to the second stage mini-skirt and encapsulated a portion of the second stage. The second stage included an Aerojet AJ10-118F liquid bipropellant engine with fixed calibrated thrust and multiple restart capability, and a digital inertial guidance system. The third stage used either a Thiokol TE 364-3 or TE 364-4 solid propellant rocket motor.

Delta 3920 - The Delta 3900 series replaced the Castor II motors with larger and more powerful Castor IV motors. A typical 3900 series Delta weighed 193,233 kilograms at lift-off and developed 2,807 kilonewtons of thrust.

In 1972, a four-digit number replaced the alpha-numerical designations previously used. The numbers in the four-digit code designator for Delta are:

1st Digit: Type of Augmentation/First Stage

2 - Castor II Augmentation, Extended Long Tank

3 - Castor IV Augmentation, Extended Long Tank

6 - Castor IVA augmentation, extra extended long tank, RS-27 engine, 8:1 ratio

7 - GEM solid motor augmentation, extra extended long tank, modified RS-27 engine, 12:1 ratio

2nd Digit: Quantity of Augmentation Motors

3 - Three Motors

9 - Nine Motors

3rd Digit: Type of Second Stage

1 - Standard Second Stage (10,000-pound propellant, TRW LEM-D engine)

2 - Uprated Second Stage (13,200-pound propellant, AJ10-110K / AJC ITIP engine)

4th Digit: Type of Third Stage

0 - No Third Stage

3 - TE-364-3 third stage (1,440-pound propellant)

4 - TE-364-4 third stage (2,300-pound propellant)

5 - PAM STAR 48B third stage (4,430 Ib propellant maximum)

PAM - Initially when PAM was used, the fourth digit was zero and "/PAM" was added to the designator - for example, 3910/PAM.

Suffix: Fairing

None - Standard 9.5-ft diameter, 27-ft 10-in. long fairing

-8 - 8-ft dia, 26-ft long fairing

-10 - 10-ft dia, 26-ft long fairing