The Fairchild J44 Project: Restoring a J44-R-24 turbojet!

[duncan]

October, 2019

Greetings all, I am starting this new thread in the new "section", "Projects and Ideas", to cover my circa 1955 Fairchild J44 turbojet engine.  I have been posting about this project on JATO since I first started with it over 5 years ago, as you may know.  It has gone from a tired old engine to a restored shining gem that runs once again!  The engine ran after getting it on a stand & connecting it to power & fuel; however, it had internal hot section damage & that desperately needed to be addressed before a catastrophic failure occurred.  At that point, I decided to disassemble the engine & replace the bad parts, if possible.  Parts are nearly impossible to find for these obscure engines but coincidentally, the fellow that I bought this engine from had a 'parts engine' laying around, so I bought it.  It was apparently in good shape upon disassembly & inspection,  so it was a great source of replacement parts for my hot section!  Thanks to Agent JayZ of Jet City Turbines for balancing the rotating assembly & to Mark of BoMar Industries for his talents in design & fabrication of the stand, 'special tools' & the like.

I was able to find brand new ball bearings & seals for this engine, due to its simplistic design & standard sizing!  They are a bit costly but they are high precision, 18,000 RPM rated, so expect to pay for these!  Most casings & castings were glass bead blasted & then either powder coated (electrostatically painted), painted with glyptal type paint or just polished.  Please see all of my videos on my You Tube channel, "Darren Duncan" for all of the details.  I videoed just about everything, so, lots of dry & boring material, if you are interested.

The engine was started for the first time after restoration this Spring, May of 2019.  There are 2 'new' videos posted covering these latest runs, including the 'stand cam' GoPro in its water tight case, revealing the nice, smooth rotor, gears & bearings sounds otherwise masked & covered by the loud exhaust & air rushing through the engine!  You can see the tree limbs blowing in the jet wash 70+ feet away, with only a low power setting of 40%!

There is more to come, including some electrical system modifications & a larger fuel boost pump for the stand.  I will post videos on You Tube & try to post some photos here on JATO, as I can.  Check back once in a while.  Thanks for everyone's interest & support.

Cheers,

Darren Duncan

[duncan]

The very beginning: Picking up the engine at Paul's, building the stand, making a 28 VDC supply, making an electrical control box & console, plumbing & wiring the engine on the stand & then testing the systems before trying to start the engine.

[duncan]

This is my original J44-R-24, disassembled after verifying that it ran, which was really depending upon the fuel control system being operational.  It seemed to function OK so I went ahead with the idea of restoring the engine.  You can see the badly damaged turbine stator (nozzle), which was disintegrating!  If your stator looks like that, you want to replace the turbine too, which then requires a balancing procedure be performed on the rotating assembly!  The combustion chamber looked bad as well, so I used the parts engine combustor, to go along with the turbine & stator.  You can see the crust & carbon accumulated inside of the original.

[duncan]

Here are most of the parts & assemblies, after clean-up & paint!  Lots of detail, some of which is not necessary, like painting the screw heads, etc. but it adds a nice touch!  I used original fasteners everywhere except some external locations, where I used stainless steel fasteners.  I tested the original oil mist lubricator assembly before installing it in the diffuser housing.  Once inside the engine, it is not accessible so be sure it works before closing her up or you may not have lubrication for the 2 rotor bearings!  The 12 original fuel nozzles were reused, after cleaning & spray pattern testing.  I did not bead blast the compressor rotor or the main shaft, which are coated with an anti-oxidant.  The original accessory drive gear box had been damaged by a rusted/frozen bearing so I used the parts engine gear box.  I replaced all bearing & seals then had it painted to match the intake housing powder coat color.  I have a couple of friends in the automotive paint business!  You don't have to paint any of this but it is made of aluminum, so a coating or anodizing is needed to prevent oxidation!  The factory coatings, if good, are probably better, & definitely cheaper!

[duncan]

Here we see the final assembly, putting the sub-assemblies together starting with the intake housing & rotor, working towards the exhaust nozzle housing, 'stacking' them one then the other.  Notice that the engine must be in a vertical orientation to assemble the 'core' containing the rotating assembly, suspended by the 2 bearings.  Once the screws fastening the intake & exhaust housings to the cowl are installed & torqued, the engine may then be rotated to horizontal & mounted on a stand for installing accessories.  Mark of BoMar Industries had to fab a tool to hold the large spanner nut at the front (compressor) end so it may be tightened, securing the rotor shaft in place.  Lastly, the exhaust nozzle extension & 'air ejector' are installed.

Thanks to another Mark, of Earl's Indy Serviceshop, located in Speedway, Indiana, who was patient with me & supplied miscellaneous fittings & lines, including those beautiful stainless oil & air lines for the turbine bearing!  I bent them to match the originals.

[duncan]

These pics show the completed engine & in action at a buddy's farm!  Power was never increased above 50% RPM so no restraints required to keep it in place.  Since these runs, I have replaced the fuel line from the fuel valve to the fuel manifold, which was leaking.  Check out the start sequence of pics, showing the inevitable torching of these single stage turbine jet engines.  EGT rises but never to maximum temp, then quickly drops to about 500 C & the whole process lasts about 3 - 4 seconds.  I am experimenting with a couple of different types of spark plugs to try & improve starts.

See video of this day on my You Tube channel, "Darren Duncan".  Thanks to Fran for posing with the engine & photographing the runs; thanks to Agent JayZ for his support & inspiration as well.  Please see his many, many instructional videos about gas turbine engines, on his You Tube channel, "Agent JayZ"!  More to come as the project progresses!  Thanks again for your interest & following.

Cheers,

Darren Duncan

PS:  Don't forget your fire extinguisher(s)!  I have 2, one is a CO2 (carbon dioxide) & the other is a foam for liquid fuel  fires!  Dry chemical is corrosive to aluminum!!!

[racket]

A beautifully restored engine , you should be very proud of her :-)

Hopefully many years of fun to be had .

Looking forward to hearing more

Cheers
John

[duncan]

Oct 28, 2019 19:43:00 GMT -5 racket said:

A beautifully restored engine , you should be very proud of her :-)

Hopefully many years of fun to be had .

Looking forward to hearing more

Cheers
John

Thank you, sir!  It has been fun.... and rewarding!  There is satisfaction in pulling this off but designing your own combustor (combuster?) is way deeper!  You seem to know your way around them so kudos.  If you look at the J44 combustion chamber, you can see it is annular & has a simple circular fuel manifold using oil furnace fuel nozzles.  This is such a simple engine, so it is a good beginner's project candidate.  I am interested in something a bit newer but still affordable, such as a GE CJ610 or similar (outdated) small business jet engine.  As for overhauling something that complex, I won't make any promises.  Maybe a good 'runner' that is near its life hours, no longer certified for air use.  Thanks again for your interest.

DD

[racket]

Yep, I was very interested in the flametube , especially the colouration pattern

The Fairchild was a bit of an oversized RC micro engine , low compression at 2.7:1 and a specific thrust of only ~40 lbs/lb of air flow , similar to what we can get from a DIY turbo based turbine engine , it was an engine that gave me inspiration when first playing with my TV84 engine .

Cheers
John