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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. |
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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. |
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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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