Project Sidewinder

[racket]

You might be pushing a HX82 to get 200 lbs with A/B unless you fit a larger comp that will flow ~3 lbs/sec at good efficiency , a couple of truck turbos with inducers of 88mm might be a better solution

[rocketman_mike]

In a very interesting turn of events, someone at work saw the kart in the back of the truck and revealed that he has built several of these turbojet engines and a couple of pulsejets. His name is Adam and he's built a pulse-jet powered ice speeder.


heres a link to his youtube. He's got some really cool projects and he's itching to start building another turbojet. www.youtube.com/@adamberdan14/videos 

Adam came over we combed through what I have built so far. I'm so glad to have recruited some more brains and experience to give me a second set of eyes. He noticed some hot spots on the flame tube, which we determined had to be a result of having three fuel spray nozzles most likely spraying fuel onto the inside walls of the flame tube. He convinced me that we need to just have a single fuel nozzle in the center, which there's already a hole in the end plate for what I believed was probably a propane injector at some point. He strongly urged to use propane to start the engine, then switch to the kero or diesel. So, we will do just that. We'll use single fuel nozzle in the center of the flame tube and use one of the three existing nozzles to inject propane and just cap off the other two existing nozzles.









We also noticed that the intake from the compressor into the combustion chamber is centered and not offset to induce a swirl around the flame tube. I think what we'll do is weld some small deflector inside the chamber at the intake to help induce a swirl flow around the flame tube. Also, I think we're going to open some more holes in the convergent end of the flame tube, right before turbine inlet to hopefully allow more oxygen into the turbine and into the afterburner. The logic being, the more available oxygen in the afterburner, plus more fuel should equal more available thrust, right? Oh, one more thing, we are adding a check valve in the fuel line before the nozzle and might be adding a pressure regulator in the fuel system. He said from his experience, just having a needle valve in the return line wasn't the best way to control pressure to the nozzles, so we'll go back to the drawing board.

On a side note, Adam was concerned that the oil temps might run really high. I wasn't sure what to expect. I have a 1 gallon oil tank plus all the oil in the lines running to the 10 row cooler in the front of the kart is at least another two quarts of oil.
My current oil flow goes: turbo outlet->tank->pump->filter->cooler->turbo inlet. Adam suggested having the pump pull oil from the cooler instead of straight from the hot tank. So the new flow will be: turbo outlet->tank->filter->cooler->pump->turbo inlet. This will help keep the pump at a cooler temp, but also reduce any pressure loss between pump and turbo inlet. Should be a pretty easy fix just to move some hoses around.

Something really exciting happening: Rocketman Robert Maddox has offered to help fabricate my afterburner nozzle since I've had some difficulty sourcing a stainless cone in the size I need. I'm a huge fan and have been watching his builds for a long time now, so it's so cool to have him help me with this project. His pulse-jet projects are not only functional and impressively powerful, they are works of art.



Im also revisiting the ignition system...again. Im almost certain I burned up the HV generator after feeding it direct 12V. The cheap HV generator didn't like that much sauce. So I tried wiring a voltage step-down to 6V but havent tested it yet. This time, I'm using three HV generators, each powered by a 9v battery and triggered with one of the momentary switches on the steering wheel. Im not entirely sure why there's two spark plugs inside the flame tube, but since they're there, might as well use both of them.

Meanwhile, Adam is laser cutting some gaskets to seal up the combustion chamber end caps and we're designing brackets to mount the throttle valve and digging up the single fuel nozzle.

[racket]

Nice PJ sled :-)

Yep , a single spray nozzle is preferable , BUT , the atomisation from the larger nozzle will be poorer than from the 3 smaller ones unless the fuel pressure drop across the nozzle is increased , perhaps combustion issues necessitated the 3 nozzles .

With your delivery tube to combustor orientation is concerned , a tangential delivery isn't always a good idea , it can create problems , the best setup is to have the delivery tube empty into a funnel plenum on the outside of the combustor can , the larger flow area from the plenum into and around the flametube in both directions is less likely to cause combustion problems , if possible fit the delivery tube to the bottom of the combustor jetandturbineowners.proboards.com/thread/78/garrett-gt6041-powered-kart?page=6 this allows air time to sort itself out as it travels up the outside of the flametube to the primary holes

Adding extra holes at the outlet end of the flametube isn't a good idea , you need to have both the total area of the holes and their division within fairly tight limits , extra holes at the outlet can starve the Primary holes with combustion problems resulting , stick to the standard design , we need to burn a certain percentage of the air to produce the temperatures required to power the turbine to drive the comp , we can't fudge the numbers , it doesn't work that way :-(

Bob Maddox certainly makes some nice machines :-)

The HV generators have pretty limited duty cycles , maybe have it on a press button to get the propane alight .

Cheers
John

[rocketman_mike]

Just a little update on the kart. I've been just combing through and fixing some little things, but I've been having an issue with the oil pump. Just days before I was going to attempt a first official start, the oil pressure just died and the pump sounded horrible. I took the pump apart for inspection. Found some junk caught in the diaphragms, but nothing really hindering the pumps operation. There was a load of oil pouring from the motor itself. I disassembled the entire pump, cleaned it all out and cleaned the commutator and brushes. It ran like brand new until I start feeding oil back to it. As soon as it began building pressure, it died again and oil feeding back into the motor. So, I've ordered a new pump for now and will rebuild this one as a backup if I ever need it. Fuel system seems to be working as designed. I have several spray nozzle options to experiment with. Added an oil breather/expansion overflow tank. We now have a 3D printed ignition box with HV ignitors for each spark plug. I the kart configured to start on propane then we can switch to diesel. Depending how soon the new oil pump arrives, I'm shooting for first start next weekend.

[rocketman_mike]

[racket]

Lookin'good :-)

[rocketman_mike]

Ok, so after a crazy couple of weeks between dookie weather, tornado warnings, and hail, I finally got the new oil pump installed with a regulated return back to the tank. As soon as I fired it up, the pressure readings were all over the place. I reverted back to the analog pressure gauge and that seemed to fix that problem. Now, we have consistent and controllable oil pressure. All that's left is to install and wire up this sweet 3d printed ignition box that Adam designed for me and fabricate some gaskets to seal up the combustion chamber. Someday real soon, I will muster up the courage to light this candle. Meanwhile, the deathtrap seems to get a lot of attention everywhere I go. To add to my current distractions and work loads at the rocket ranch, I was also accepted to Embry-Riddle Aeronautical University in Daytona. So, in the coming months, Im going to be busier than a squirrel in a nut factory.

[racket]

Congratulations on your Uni posting :-)

Yep , the locals are "interested" , I've often wondered what they're actually thinking ;-)

[rocketman_mike]

We were so close to getting it to fire up for the first time. Had the turbo spooled up, propane flowing.......and then the cheap amazon HV generators burned up. No spark. So, Im going to build the ignition the way it should. Im going to use a coil pack from a V6 mustang, feed 12V to the input and trigger it with a flasher relay. In theory, it should work.

[racket]

Yep , thats what I built for my bike 30 years ago , I think I also had to add a light globe somewhere .................LOL, just checked my "drawing??", it also had a relay that was operated by the flasher , the relay was in the earthing of the spark coil and the light globe was in the earthing of the relay .

Positive from battery to #49 on flasher unit and positive on coil .

#31 on flasher to earth negative .

#49A om flasher to #85 on relay .

#86 on relay to globe then earth negative

Negative on coil to #87 on relay

#30 on relay to negative earth

It worked for years :-)

Cheers
John

[rocketman_mike]

ok, so when it comes to electricity and ignition systems, Im apparently stupid. Now that's established, let's begin. I'm giving the cheap HV generators the boot and wanting to use an automotive coil pack because it's robust, relatively weather resistant and I can feed it the 12V juice with no issues. I found this coil pack from a ford v6 mustang. It's a wasted spark system, using three coils which I thought would be ideal for my three spark plug system (2 in the flame tube and 1 in the afterburner). I begin looking into the wiring schematic for this system and now Im lost. I originally thought it would be 12V going in on the primary circuit and the other 3 pins would be grounds for each coil. Thats apparently not the case. Now, I have no idea how to trigger this coil pack without all the other EDIS control module and crankshaft sensors and everything else this system normally uses. Im reaching out to the big brains in the forum for help. I found an article that goes into depth how this system works assuming it's installed in a car for its intended purpose, but Im still lost

www.fordforumsonline.com/threads/dis-edis-ignition-systems.265/ 

[rocketman_mike]

so, after doing some more digging on this rainy day, I've come to the conclusion that the Electronic Distributorless Ignition System (EDIS) module has the actual ignition coil driver built-in - the driver is not part of the Ford wasted-spark coil pack. The coil packs are just standard ignition coils, and could in theory be substituted with other coil-only packs. So, I have the EDIS-6 (for 6 cylinder, 3 coils) module ordered. The 4-pins from the coil pack are wired to the module as such:



The module will still trigger the coil without the SAW and PIP signals. Those signals would be used for timing purposes from a Megasguirt controller to advance timing if used on an internal combustion engine. The only thing I'm focused on is the trigger signal from the "VR" or variable-reluctor sensor (crankshaft position sensor). It sends a square-wave signal to the module which I believe the module uses to make the trigger signal to the coil pack. So, I have to generate the square-wave or basically trick the module into triggering. I think the signal is most likely low-voltage, 2.5-5V. I'm thinking using a flasher relay with an adjustable buck converter. I can set the buck converter to 2.5V and trigger that with the flasher relay.

[rocketman_mike]

alright, now that birthday weekend is over, I can get focused on the task at hand: ignition system. I scrapped the Ford EDIS coil ignition idea as that was turning into a headache trying to trigger the control module to fire the coil. Instead, I revert back to a simple ignition coil x3, in this case some coils from a general motors LS engine like a corvette. These coils are used on a wide variety of their cars and are easily picked up at any local parts store. Im still using a buck converter to take 12v down to 5v and use an NE555 timer to trigger these coils. It surprisingly works. I assembled everything on a backing panel and verified everything works. I now have to move the assembly to the kart which required some modifications to the box containing the converter and timer, but it would seem everything will now fit where I want them. The only thing standing in my way is some miserably hot Florida weather mixed with some random torrential downpours sprinkled with lots of lightning. 

[rocketman_mike]

HUGE MILESTONE!!!! WE ARE RUNNING!!!!! Don't quite have the full ignition system wired up, but we temporarily wired up a taser to the spark plugs to todays test. We had to modify some of the plumbing to allow more propane flow during start, but other than those two trivial issues, it fired up and idles beautifully. The little battery powered leaf blower we were using didnt quite have the ass to spool it up, but once I plugged in the compressed air, BOOM! She lit off. During the chaos, I forgot to hit the record on my phone, so the gauge readings i was trying to collect are gone, but one thing I did see was that I lost one of my EGT gauges, I'll be digging into that problem and see whats up with that. I didnt get a chance to see what kind of P2 pressures at idle. So, moving on, I will finish wiring up the ignition system, I have some leaks around the CC end caps to seal up and I need to make some gaskets for the fuel nozzle as I saw some leaks around that as well. I can see that the toroidal effect inside the afterburner is working and is exactly where the spark plug location will be, so that looks very promising. Didnt really get out of idle, but I can hear the rpms pick up when I started feeding the diesel into it, I just dont think I had enough diesel pressure before I killed the propane and the whole engine shut down.
www.youtube.com/watch?v=uBAZjQvIplM

[racket]

Congratulations :-)

Yep , those axial blowers don't produce "pressure" , pressure is needed during a start , radial comp blower required.

Now comes the fun part :-)