Well, I decided I wanted to make an automatic start for the HR-1A engine. It had to be capable of starting the engine up quickly, and it had to be really cool. Cool is what I got as you will see later! I still have a ways to go to make sure everything is working, but I did get a lot done so far. Although I was originally looking at making a starting system that would attach to the compressor nut, I decided to try compressed gas and air impingement first to see how it would work out.

CO2 tanks for the air start

The idea behind my crazy scheme is to impinge air directly on the turbine blades. Actually, I plan on using compressed CO2, as it has a lot more punch to it and can easily fit into small bottle. I started by pickup up some small 20oz capacity CO2 cylinders that are used for paintball. I picked up the tanks from Wayne at Morgan's Furniture in Okeechobee, Florida. He has a side business of filling paint ball tanks and has a line of paintball supplies as well.

Duckbills and expansion tank

The fittings on the top of the CO2 tanks are specialized valves for use in paintball, called pin valves. The valves automatically open as you screw the tank into the adapter on the paintball gun. The adapters are called "duck bills" as they resemble the bill of a duck. They have a fitting to screw on the tank on one end, and a 1/8th inch pipe thread output fitting. The CO2 is stored in the tanks as a liquid and turns into a gas as it leaves the tanks. Because of this, it gets very cold as the expansion of the gas causes an evaporative effect. To help with that I purchased an expansion tank which can bee seen with the blue duck bill attached to it. The expansion tank has a 1/8th inch threaded input, and the output looks just like the valve on a CO2 tank, so a duck bill can be used to connect plumbing to the output. The final piece in the photo above is another expansion tank, just in case I need one!!

Lots of fittings

To make sure that I had more than enough fittings for the job, I made a trip to the hardware store and picked up a few!! I didn't want to have to make a second trip so I bought way more than enough, but I will probably still run out as this always seems to be the case. No matter how many you buy, you still need more of the little buggers!

Solenoid valves

I also picked up some 12 volt solenoid valves off of Ebay so that I could make the whole system operate via the computer later. These valves will hopefully work with the high pressure CO2, but if they don't I will find another use for them somewhere.

Solenoid close up

The valves use a 1/8th inch pipe thread, so I can keep everything standard with the air start system. I will have one of these on the output of every CO2 tank in the system so I can change from one bottle to another quickly. If I just opened up one bottle, then another was added to the system, there would be a loss as pressure flowed from the full bottle to the empty one. By only having one CO2 bottle on at a time, I can get the maximum expansion of the gas and get more power. More power is always a good thing!!

Parts all connected

I started by connecting the basic CO2 components together. The bottle will attach the the duck bill on the far right in the picture above. I am using a ball valve for the initial test to make sure the system works before adding a solenoid valve which could add to the complexity. If I get this part to work first, then I can add the solenoid valve knowing that everything else is already working OK. The CO2 will leave the tank and go through the first duck bill, and then to the valve (either manual or solenoid). From the valve it will go to the expansion chamber and convert fully from liquid to gas, before being sent on to the engine.

Connection to the engine

I had wanted to be able to just drill a hole in the turbine housing for the CO2 to impinge on the turbine, but it did not work well. I decided instead to get it as close to the turbine wheel as I could. I started by using a brass compression fitting for 1/4 inch tube, and drilled it out so that the tube could pass all the way through the fitting. Normally the tube would only go about half way in to the fitting and sit against a small seat there. I then used some stainless tubing I had laying around the shop to make the air impingement nozzle which goes through the fitting in the turbine housing and situates the nozzle right near the turbine blade tips. Since I wasn't willing to risk damage to my good turbine housing, I used my old one which had seen some melting to the divider in the turbine scroll. It will be just fine for the tests. If the system works well, then I'll just make the same modifications to the good turbine housing I have.

The turbine impingement nozzle

The nozzle comes to rest inside of the turbine housing right near the blade tips. You can just barely make it out here as it peeks through the opening in the housing where the engine gasses normally make their way through to the turbine blades. I will have to experiment with the nozzle to see if it needs to be made any smaller for better pressure.

I am impinging the start air on the turbine side of the turbo so that I do not starve the engine of oxygen during starting. Since CO2 would act as a fire suppressant, impinging on the compressor side was out of the question. As it turns out, the system works better on the turbine side anyway. It is nice to see something go in my favor once in a while.

Rpm computer

When I spin up the turbo for the tests I need to get a good ideal of how fast it will actually go. Since I recently received my RPM computer, I mounted it on the test stand and hooked up the fiber optics to the engine.

RPM computer in the new housing

I wanted to be sure the computer was shielded from debris and well protected, so I made an enclosure for it first. I took a small box and milled out the panels on the mill for the screen and also for the programming connector, power, and sensor wires. I then used rubber grommets to seal and protect all the wires coming out of the enclosure. What I ended up with is a very nice little computer that does a great job of reading the RPM.

Installing the CO2 tank

If you look carefully you will see me installing the CO2 tank in an upside down position on to the duck bill at the right. With everything connected, I am ready for the first test!

This thing is cool!

I told you this thing would be cool! The parts of the system get so cold so fast, that a frost layer forms on everything near the CO2 tank. By the time the CO2 gets to the turbine it is still cold, but not so bad. It makes the turbine whine as it winds up to a fast speed, and gave me a bit of a shock the first time I fired it up! I did try to use the solenoid valves at this point, but they would not operate at the high pressure the CO2 is stored at in the tanks. Just my luck that the inexpensive valves don't work! I will have to pick up some cryo valves from Ebay, and it was suggested to me to try the ones from Design Engineering for their CryO2 systems. Those valves had better work for this!

So the question is, how does it work? Very well so far! And it sounds great. Fortunately for my readers, I have put up a video below of the system so far. There are still some bugs to work out, but things should start to shape up quickly. Check out the videos and don't be surprised too much by the sound of the engine whining as it spins up! You will notice that the combustor has been removed for these tests to make it easier to change things around while I develop the air start system.

The next step is to see if I can get it to spin up fast enough to start. Using the normal starting method of the shop vac, I could only get the turbo to spin up to about 3000 RPM. Using the CO2, I have gotten it to spin up to 6600 RPM so far. Only further tests will show if this is fast enough or not. The engine has proven to be hard to start with the shop vac in the past, requiring long spool up times anyway, so hopefully this can be overcome with the faster starting RPMs. To see what I mean, check out the video of me starting up the original HR-1 engine on the jet kart by clicking here.

Air start testing

I will be adding a fire suppression system to the jet kart later using this same type of setup. The suppression system will spray CO2 into the motor area to contain any fires that may break out, although I certainly hope that I never have to use it!!

I hope you've enjoyed following along so far. I will continue testing the starting system until I get it working properly and can fire the engine with it consistently. Keep checking in, and remember to support the site with your donations or through sponsorship!! Thanks!

Gary Richards

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