Project Jet Kart

building and testing the engine

Work has progressed further now! We have the engine now mounted on a test stand for testing purposes. This allows us to run up the engine and try new things throughout the after burner development. The engine test went very well. Engine starts up and idles smooth. We are currently using a 15gph fuel nozzle, however, this will need to be changed out to a 20-25gph nozzle. Because of the fuel nozzle limitation we are limited to running the engine at 1/2 throttle. However, at half throttle here are some figures;

Engine Idle - 23,000 RPM

Engine 1/2 throttle - 38,000 RPM

Fuel Consumption at 1/2 throttle - 15gph

Compressor Pressure - 13psi

EGT (exhaust gas temp.) - 780 F

Fuel - Kerosene






We also have a new video of the engine on its first run. I apologize for the quality of video, it was at night, and with a digital camera that does video, but we will have some high quality video up soon of the engine. You can view the video by clicking HERE (54MB download)

Two new video's have been added to the multimedia page! Click HERE to check them out!


Time for another update! This update is pretty big, so make sure you check out all the great pictures.

After several good runs on the engine, a problem had started to develop. During combustion, flame tube expansion was creating pressure on the top combustor lid causing the lid to warp. A new flame tube and lid had to be constructed. Thanks to russ over at www.badbros.net we will be using a "free float" design. This allows the flame tube to expand and to be changed if needed.







So as you can see, this was quite a bit of work making a new lid that was thicker (3/16") and centering everything so that it would line up correctly. If you haven't figured out how it works yet, the flame tube "necks down" to fit into a coupler fixed to the bottom of the combustor. The top of the flame tube then sits in to the top coupler on the lid. In a sense the flame tube is "sandwiched" between to the lid and the bottom of the combustor.

When together you can actually hear the flame tube rattle a bit in inside the combustion chamber, until it heats up. Once hot, the flame tube expands and fits tight in the couplers. Clearances are less than 1/32".

After running the engine for the first time after the rebuild of the combustor, we suffered some major problems. The engine was flaming out every time on spool up. We tried several different methods of starting but could not get the engine to start. Every attempt ended with a couple loud bangs and some vaporized kero exiting.

After some inspection it was found that the source of the problem was the coupler around the top of the flame tube was not tight enough, allowing in extra air. This was fixed and a successful run on the engine was performed. The kart is really wanting to take off now! A long day in the garaged proved to be very productive. New motor mounts have been installed and the engine now sits neatly on the kart.









Its obvious how much cleaner these new motor mounts are and how much stronger as well. We were able to reuse the old go-kart fuel tank for our oil tank (blue tank under engine).

After a couple days with no sleep, it was now time to venture into the afterburner construction. We have discussed a couple different design ideas, but decided to stick with our original idea for the main reason that it was a tried and true design that worked on our previous engine, though much, much bigger. Afterburner construction took just about all day, with several problems that we had to work through, in the end it came out very nice.





The design is actually fairly simple. We go from a 5" to 8" step up pipe. Overall afterburner length is 24" long. We are using a fuel ring with 6 1mm holes that will flow approx. 40gal/hr. The vapor gutter is visible behind the fuel ring, and a spark plug is located about half way down the pipe. I hope to have the new video up soon of this beast in action!

 

Once again, we are back at the table for another update! Testing of the afterburner failed. We were unable to get ignition using a spark plug. We tried several different spark plug positions but were unable to achieve ignition.

After some brainstorming I came up with the idea to use a system that most modern jet aircraft use on their afterburners. This system is a torch system. You can almost think of it as a mini-flame tube. A small amount of fuel is ignited by a spark which jets out a "torch" into the afterburner.

The Parts that will be used to make the torch system.

A hole was cut to accept the threaded piece in which the whole system will screw into the afterburner. You can see where the torch will sit on the afterburner, just behind the vapor gutter.

Threads welded to the afterburner.

Here is the completed torch.



Torch installed into the afterburner.

Please go to the multimedia page to see more pictures and video's

 

BAD NEWS!

Well, the kart engine suffered turbine failure. The bad part is, this A/R turbine is no longer available so the jet kart is sitting at the moment while I work on a solution to this problem.

 

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