Method of fabricating a rocket engine nozzle using pressure brazing

1. A method of fabricating a rocket engine nozzle comprising:

assembling a nozzle jacket and a nozzle liner to provide a rocket engine nozzle assembly, the nozzle liner having a plurality of channels, the space between each channel defining a land, and the nozzle liner having at least a pair of endlands disposed at each end thereof;

sealing the nozzle assembly at a forward end and an aft end of the rocket engine nozzle assembly with a plurality of seals, wherein the seals are provided between the nozzle jacket and the endlands of the nozzle liner; and

bonding the nozzle liner to the nozzle jacket by pressure brazing the rocket engine nozzle assembly using a single pressure brazing operation after said sealing step.

2. The method of claim 1 , wherein the bonding of the nozzle jacket to the nozzle liner by pressure brazing comprises:

evacuating the rocket engine nozzle assembly;

placing the rocket engine nozzle in a furnace;

pressurizing the furnace to a brazing pressure;

increasing a temperature in the furnace to a brazing temperature;

holding the brazing pressure and the brazing temperature for a brazing period; and

decreasing the temperature in the furnace while holding the furnace pressurized at the brazing pressure.

3. The method of claim 2 , further comprising determining a brazing pressure range, a brazing temperature range, and a brazing period range, wherein the brazing pressure is within the brazing pressure range, the brazing temperature is within the brazing temperature range, and the brazing period is within the brazing period range.

4. The method of claim 3 , wherein the determining is performed by a finite element analysis.

5. The method of claim 1 , wherein the assembling comprises placing a brazing alloy between the nozzle jacket and the nozzle liner, the brazing alloy bonding the nozzle jacket to the nozzle liner during pressure brazing of the rocket engine nozzle assembly.

6. The method of claim 1 , wherein said seals are formed by brazing the nozzle jacket and the nozzle liner at a forward end and an aft end of the rocket engine nozzle assembly.

7. The method of claim 1 , wherein said seals are formed by welding the nozzle jacket and the nozzle liner at a forward end and an aft end of the rocket engine nozzle assembly.

8. The method of claim 1 , further including that said seals remain in place after said bonding step.

9. The method claim 1 , further including that said endlands remain associated with said rocket engine nozzle assembly after said bonding step.

10. The method of claim 1 , further including that said seals sealably enclose any space between said nozzle jacket and said nozzle liner.

11. The method of claim 10 , wherein said seals form closeout bonds.

12. A method of fabricating a rocket engine nozzle by pressure brazing comprising:

determining a brazing pressure range, a brazing temperature range, and a brazing period range based, at least in part, on a finite element analysis;

assembling a rocket engine nozzle jacket and a rocket engine nozzle liner to provide a rocket engine nozzle assembly, the rocket engine nozzle liner having a plurality of channels, the space between each channel defining a land, the rocket engine nozzle liner having at least a pair of endlands disposed at each end thereof; and

sealing the rocket engine nozzle assembly with a plurality of seals, the seals provided between the rocket engine nozzle jacket and the endlands of the rocket engine nozzle liner; and

pressure brazing the entire rocket engine nozzle assembly using a single pressure brazing operation after said sealing step, the pressure brazing operation using a brazing pressure from the brazing pressure range, a brazing temperature from the brazing temperature range, and a brazing period from the brazing period range.

13. The method of claim 12 , wherein the determining comprises:

performing a finite element analysis to determine an estimate of the brazing pressure range, an estimate of the brazing temperature range, and an estimate of the brazing period range; and

performing a pressure brazing on at least one subscale model of the rocket engine nozzle assembly with the estimate of the brazing pressure range, the estimate of the brazing temperature range, and the estimate of the brazing period range to determine the brazing pressure range, the brazing temperature range, and the brazing period range.

14. The method of claim 12 , wherein the sealing comprises brazing the nozzle jacket and the nozzle liner at a forward end and an aft end of the rocket engine nozzle assembly.

15. The method of claim 12 , wherein the sealing comprises welding the nozzle jacket and the nozzle liner at a forward end and an aft end of the rocket engine nozzle assembly.

16. The method of claim 12 , wherein the single pressure brazing operation comprises:

evacuating the rocket engine nozzle assembly;

placing the rocket engine nozzle in a furnace;

pressurizing the furnace to the brazing pressure;

ramping up a temperature in the furnace to the brazing temperature;

holding the brazing pressure and the brazing temperature for the brazing period; and

ramping down the temperature in the furnace while holding the furnace pressurized at the brazing pressure.