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J-58 Engine of the SR-71 Aircraft

ClammyBozeman
Education>Engineering
IP Report

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J-58 Engine Profile
J-58 Engine Profile
Designer
30.7 h
15 plates
4.8(6)
Open in Bambu Studio
Boost
340
772
23
26
354
45
Released 

Bill of Materials

List other parts
  • Super Glue x 1: Super Thin
  • 608 2RS Ball Bearings x 2:
  • M3 x 8 hex socket head cap screws x 8: black-oxide
  • M3 Hex Nuts x 8: black-oxide
  • M2 x 6 hex socket head cap screws x 7: black-oxide
  • M2 Hex Nuts x 1: black-oxide
  • M5 Hex Nuts x 1: Stainless Steel
  • M5 x (12 or 15) button head screw x 1: Stainless Steel (Depends on my adjustments to the model)
  • M5 Washers x 1: Stainless Steel

Description

 

The Pratt and Whitney J-58 engine is the engine of the SR-71 Blackbird, a strategic reconnaissance aircraft used by the United States Military. This is known amongst engineers as one of the greatest engine planes ever made due to its unique engine.

 

Usually, there are three types of engines: turbojet, ramjet, and scramjet. Most planes use a turbojet engine as ramjets, and scramjets rely on the forward motion of the plane to generate thrust and, therefore, need to be moving at least Mach 2 (for ramjet) or Mach 5 (for scramjet). The SR-71's engine is unique in that it combines the concepts of the turbojet and ramjet, making a turbo-ramjet engine. The plane used the turbojet to fly off the ground and then switched to ramjet mode once it reached Mach 2. The plane reached a max speed of Mach 3.2, 2455 mph or 3951 kph, essentially flying a mile in under a second.

 

There are many videos explaining the J-58 engine, so I'll put links below.

 

There are five main sections to my model, which contain the housing shell of the engine, the compressor, the combustion chamber, the afterburner, and the iconic bypass tubes. Due to running out of time for the engine competition, I could not design the afterburner's variable propelling nozzle (the flap-thingy at the end of the engine). At some point, I will add this and other parts of the engine, but I need more time. I may remix Linus3d's variable propelling nozzle as it looks quite good, or I may design my own, but this feature will be added. After I add this feature, I intend to add LED lights, design the inlet spike, and maybe the SR-71's start cart that was used to start the engine on the ground.

 

Bill of Materials:

 

Superglue (Thin works best)

8x M3 x 8 hex socket head cap screws

8x M3 hex nuts

7x M2 x 6 hex socket head cap screws

7x hex nuts

2x 608-2RS ball bearings

2x M5 x 12 button head screw

2x M5 hex nuts

 

 

Supply Links:

 

 

Printing Instructions: 

Unfortunately, I don't own a Bambu Labs printer, I have a Creality printer. That being said, the printing tolerances are undoubtedly going to be better and different on any Bambu Lab printer. I tried to adjust the tolerances as best for everyone, but please contact me if there is a problem with the tolerances on a Bambu Lab printer.

 

The model contains very few supports. I set the print profile to the standard 15%, but I used 5 to 10% infill on some prints to save filament. Please feel free to adjust the infill, but do so at your own risk. The only tricky section to print is the front housing unit of the engine; the very top has a slight overhang that may turn out rough. I turned off supports for this, but you may want to turn them on as the tolerances of this section are important. However, a Bambu lab printer might be able to accomplish the task without support, I am unsure. Please feel free to ask questions. Use supports for the flame ring, torch igniters, and the combustion canister(the very small spot where one of the cans is cut in half, you'll see it).

 

And for the love of everything, please print the bypass tubes. It doesn't seem like much, but the tubes are the key feature of the engine.

 

 

Assembly:

Start by attaching the inter-connector tubes to the combustion canisters. They should snap in place. Then, apply glue to lock it in place.
Snap in the bearing. (If too loose very carefully apply glue to the outside of the bearing)

 

Snap in the bearing, same as the previous step
Insert the M3 nuts into the slots. Because I did not use supports, I needed to soften the part with a heat gun so the nuts could sink in, it depends on the quality of your printer.
Attach the 7 M2 nuts to the end of the midsection housing (if needed apply a drop or two of super glue around the nuts).
Next, attach the front housing to the Midsection housing with the combustion chamber in between using the 8 M3 screws.
Do the same with the Midsection and Rear Housing with the M2 screws.
Snap in the support struts. It's tricky, but you have to then wedge the support struts into its resting place. The best solution I found was to put it in at an angle and then twist it until it was forced into place.
Snap the Support Struts to the flame rings; it's a tight fit, but it snaps together. Use glue if necessary. (***It's much easier to do this step after the previous step)
You can now attach the CC support struts. They slide through the hole and snap in place. Glue is optional.
Very similar to the CC struts, slide in the fuel injectors.
Attach the connectors to one half of a bypass tube, then apply glue and squeeze together. Do the same for all tubes and then mount to the outside of the engine's housing. Again, apply glue as needed.
Maker sure the order of the stators is correct. They will hit the rotors if not in the correct order. 
You can attach the stators, but do not glue them. You want to be sure that the ordering of the stators is right. Make sure they don't come into contact with the rotors before gluing into place. 
Same with the stators, mount the Nozzle Guide Vanes.
The rotors are much easier to assemble. Just slide and glue them onto the main mount. Make sure they are fully flush and positioned to the bottom of their resting place. 
Next, assemble the inner shaft or axle. Glue is optional. Be sure to place one M5 hex nut at the top and bottom of the axle. 
Insert the axle into the main mount. 
Then add the turbines, similar to how you mounted the rotors
Screw the M5 bolts into the front and back of the compressor. Make sure to have a hand on the axle and screw in until finger tip tight. You don't want to it be too loose are too tight. Also, try to center the bolt as best as possible. 
After you've screwed in everything. Make sure nothing hits or prevents the compressor from spinning freely. If everything seems fine, glue the rotor mount to the axle to lock it in place. 
For the last detail, add the igniter plug. There are two parts, just fit the long part through the engine's shell and snap it into the smaller piece of the part. (With Glue)

 

sr71
engine
engineering
aerospace
mechanical

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