My J69-T-25A Turbojet Project

This is my latest project. It is a turbojet engine
from the early 60's. It is called a J69-T-25A.
These engines were used in Cessna T-37 trainer
planes. The planes were nicknamed "Tweety
Birds" not because they were gentle little birds,
but because of the noise of the engines. The planes
were origianlly nicknamed "Screamin Eagles" due
to the J69 being one of the noisiest engines around.
Somehow, the name got changed to the Tweety
Bird as it didn't seem fitting for a trainer.
The J69 being an older design from France has
a centrifugal compressor unlike modern jet engines
which have axial flow compressors. That may have
some reason for the extreme noise that it makes.
The engine sat at a university in Michigan for many
years. I bought it from Bruce at Avon Aero Supply
in Danville, Indiana with the knowledge that I may
never get it running. Needless to say, I spent two
months replacing rotted fuel lines and finally got
the ignition system to work. But, it would still not
fire off.
Here is the busines end. I spent several days
going through the fuel control trying to figure
why it would not start. Finally, I found one valve
basically rusted closed. I removed it, polished
the surfaces and put it all back together. To my
excitement, it fired right off. Two times during the
time spent, I had given up, thinking I had what we
call a "wall hanger" for show only.
Here is a video capture of my second test run.
My first was a bit of a failure as I didn't expect
my camera to get blown over. This time I had the
camera staked down at 55 feet from the exhaust.
You can see the starting flames which goes away
once the engine spools up. I did spool the engine up
to 100% and the poor camera, even at 55 feet took
a terrible beating.
So, what to do with a 1,000 pound thrust engine?
I could just run it on a test stand or mount it in
the back of "Big Red". I decided to put it in old
"Big Red". "Red" has a survivor history of going
through a serious Indiana hail storm several years
ago. About all of her had to replaced other than the
bed and doors. Even the wheel covers on the wind
side were replaced due to denting. Being a one ton
dually with a V10 engine and adding the turbojet, I
decided to call the project, a "gas/turbojet lobrid".
Unlike a hybrid, this rig does not get good economy
from the gas engine and certainly not from the jet
which burns 3 gallons of JP 4 per minute at 100%.
I did not want to ruin the integrity of the truck, so
all can be removed with only 4 bolts. The controls
are run through the sliding rear window, so are also
easily removed. I added plywood heat shields to the
rear hoping that the paint will blister on that before
the truck. One weird feature, so as not to add the
the temperature and tach displays in the cab, I have
of all things a "Fish TV" monitor in the cab to view
the gauges. I found it at a flea market and is used to
view fish under water. Well, it is now viewing my
important gauges for me. At full 100% the J69 spins
at 21,700 rpm and produces 1,000 pounds of thrust.


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