LR-87

LR87

XLR87 Rocket Engine
Country of origin	United States
Manufacturer	Aerojet
Application	Titan Main engine
Liquid-fuel engine
Propellant	LR87-3: RP-1/LOX LR87-5, LR87-7, LR87-9, LR87-11: Aerozine 50/N2O4 LR87 LH2: LH2/LOX
Cycle	Gas-generator
Performance
Thrust (vac.)	733 kN
Thrust (SL)	LR87-3:647 kN
Chamber pressure	40 to 59 bar
Isp (vac.)	2,840 N‑s/kg (290 s)
Isp (SL)	2,510 N‑s/kg (256 s)
Dimensions
Length	3.13 to 3.84 -LR87 LH2: 4.00 m
Diameter	1.14 m
Dry weight	839 kg

The LR87 was an American liquid-propellant rocket engine, which was used on the first stages of Titan intercontinental ballistic missiles and launch vehicles. Composed of twin motors with separate combustion chambers and turbopump machinery, it is considered a single unit. The LR87 first flew in 1959.

The LR87 was developed in the late 1950s by Aerojet. It was the first production rocket engine capable (in its various models) of burning the three most common liquid rocket propellant combinations: liquid oxygen/RP-1, nitrogen tetroxide/Aerozine 50 (a 50/50 mixture by mass of hydrazine and UDMH), and liquid oxygen/liquid hydrogen. The engine operated on an open gas-generator cycle and utilized a regenerative cooled nozzle and combustion chamber. Later versions had additional ablative-cooled flanges. The LR87 served as a template for the LR-91, which was used in the second stage of the Titan missile.

It was a fixed-thrust engine, which could not be throttled or restarted in flight. The LR87 delivered approximately 1,900 kilonewtons (430,000 pounds) of thrust. Early LR87 engines used on the Titan I burned RP-1 and liquid oxygen. Because liquid oxygen is cryogenic, it could not be stored in the missile for long periods of time, and had to be loaded before the missile could be launched. For the Titan II, the engine was converted to use Aerozine-50 and nitrogen tetroxide, which are hypergolic and storable at room temperature. This allowed Titan II missiles to be kept fully fueled and ready to launch on short notice.