I welded some motor mounts to the combustor as the turbo flange can support the engine from there. I bolted the combustor to the frame and built everything else around the basic placement of the combustor. I offset the turbo to the rear of the frame so the heat from the engine would not damage other parts of the system.

The motor mounts can be seen on the combustor. The mounts bolt right to the frame.

The engine is starting to look good!

       I needed an exhaust nozzle/tail pipe for the engine. The purpose for the nozzle is to accelerate the exhaust gas to provide more thrust. I decided to use 2-1/2 EMT to make the nozzle. I cut the pipe so I could taper the end and figured that a 30% decrease in size would not create too much back pressure but would have a lot of thrust. The ID of the pipe is 68 mm and the tapered end is 48 mm with an overall length of 225 mm.

The exhaust nozzle has a pyrometer sensor fitting welded into the side of the exhaust. The pyrometer will show me the exhaust gas temperature real time so I don’t risk a melt down.

       I had thought of ways to reduce my oil temperature and had remembered that the expanding LP gas (the fuel I am using) through a heat exchanger could help cool the oil. The system would probably work fine without the exchanger but I wanted to take advantage of the situation. The oil tank that I purchased was a after market radiator coolant catch tank for automotive racing use. I modified the tank by adding a 5/8” hose barb in the top for my turbo drain. The aluminum tank is perfect for wrapping copper line around as to make a heat exchanger. As the LP gas is routed through the coils, it expands and absorbs heat from the oil in the tank. I am not sure how well it will work but I am optimistic.

I wrapped the copper coils with sheet aluminum to give the unit a professional appearance

       I had one more system to hammer out, the ignition system. I had chosen to use an automotive ignition coil to ignite the combustor. I needed to figure out a way to run the coil as it needed a driver to operate. I purchased a set of points and condenser for a 65’ Chevy truck. I used a 12V DC motor from a tape recorder to drive a cam that opens and closes the ignition points. This system works awesome as I could draw almost a 25 mm spark from the coil. When I hooked it up to the spark plug in the combustor you could hear the spark inside loud and clear. See the newer solid state coil driver circuit!!!

       I now had the task of mounting my components inside the frame while making sure they would not interfere with each others operation. I had to make room for my oil pump, oil filter, oil cooler, oil tank/heat exchanger, fuel solenoid, pressure sensor, ignition system, gauges,  power panel and battery.

I welded cross members where I needed to support things. This is the main advantage of cube style framework.

I needed a place for a battery so I left room at the top for a battery tray.

       My steel fabricated parts were ready for final paint. I purchased some high temp (1200 deg.) paint for the combustor and tailpipe. I used automotive spray paint for the frame. This part of the project was exciting for me as the moment of truth was soon at hand. I just have to bolt on the parts, plumb the system and work out the control panel.

Freshly painted engine parts and frame.

       With most of the systems complete, I can start with final assembly of the engine. My hopes are that it will function correctly and I will not melt down my turbocharger before I get it running. Well, wish me luck!

Until next time.

Don Giandomenico

[Home] [What's New At RCDON] [Articles] [Aircraft Projects] [Aircraft Videos] [Aircraft Videos II] [Experimental Projects] [GR-1 Turbojet Engine Project] [GR-5 Turboshaft Engine Project] [GR-5A Turboshaft Engine] [GRV-1 Turbotug Project] [GR-7 Turbojet Engine Project] [GRV-2 Jet Bike Project] [GR Engine Series Q&A] [Readers Projects] [Experimental Projects II] [My Collection] [M.A.R.K.S. Club] [RC Links] [About Myself] [Contact RCDON]