The One Man Turbofan

[pitciblackscotland]

That's not a bad casting there mate Have you seen 2STROKE STUFFING videos on casting www.youtube.com/watch?v=vYtX8zRqqpg

Cheers,
Mark.

[monty]

Dec 25, 2021 16:11:47 GMT -5 pitciblackscotland said:

That's not a bad casting there mate Have you seen 2STROKE STUFFING videos on casting www.youtube.com/watch?v=vYtX8zRqqpg

Cheers,
Mark.

Hi Mark,

I love that guy's channel!

I think I'm going to switch to ceramic shell for these parts. Dealing with a delicate 30 lb 500 degree investment is not my idea of a good time. Mixing that much investment is no fun either. I have to burnout, and then pour sequentially. I can't let the investment cool off and use it later. It will absorb moisture from the air and require re-heating. That causes it to shrink twice!!

With the ceramic shell, I can let it cool off after firing. Wash it out with water. Re-heat it later and pour all the shells the same day. Requires a much shorter weather window...which around here means something! And the higher burnout means no problems with incomplete burnout!

Monty

[pitciblackscotland]

Hi Monty,
Yeah if you are a 2 stroke fan it's insteting to watch. sounds like what you are doing is not easy to do, keep up the good work

Cheers,
Mark.

[monty]

Hi guys,

I've been working on the new mold. If the aluminum will show up, I might get to cast later this week. Weather looks like it might cooperate. I've been fighting with the 3D printer, and I've been down an upgrade rabbit hole. I'm pushing the thing pretty hard, and it's finally begun to complain! I've upgraded the extruder and nozzle. But all this involves firmware and bunch of stuff I diddn't want to get into...but...oh well. Shipping delays have slowed me down considerably. Amazon has been flaky lately. I have nice new kitchen rug instead of the teflon tubing I ordered!! At first I thought my girlfriend ordered it for me as part of the ongoing (mostly unsuccessful) domestication efforts . I'm sure someone is wondering what the heck is this tubing stuff!! I finally built a proper enclosure for the printer. I got tired of stooping down to work on it, and running all over my shop looking for parts and tools for it. Now it's all in one place with its own dedicated bench and enclosure.

I've been working on my ignition (seems premature!!). It isn't though. I'm going to make a combustion chamber test rig. I want to be able to test things where I can see what's going on, without risking the whole engine. After looking for a tubular piece of quartz or pyrex the size needed, I've given up due to sticker shock! So I'm going to use a flat borosilicate glass printer bed instead. I'll only have a flat window to look at one side of the combustor. Should be fine, and it will avoid trying to put a spark plug through the glass.

So far I have a capacitor and a 12V HV generator. 

I am planning to use regular automotive plugs. Aviation stuff is just too hard to get and too expensive. Do you guys see any reason why a surface gap plug like this wouldn't work?? NKG has a wide selection. If not, where can I get an actual turbine type plug?

I'm also trying to get a currently manufactured spark gap. Not some old Soviet stuff off ebay. Do you guys know of any sources for this kind of thing?

This looks like it will do the task, and one of the applications listed is "turbine engine ignition systems" The 10KV one is what I was planning to use.

What type of connectors and wiring are you using between the CAP and the spark gap? I would think it needs to be spark plug high tension wire type stuff. What about radio interference? If I use non-shielded wire will the resistor type stop the noise? Since I will be using a micro-controller for the engine I don't want a bunch of high voltage noise banging about everywhere.

Monty

[pitciblackscotland]

Hi Monty,
there are some cheap turbine engine igniter plugs on the market, like this one www.ebay.com/itm/164539560648?hash=item264f5272c8:g:ETAAAOSwtEpfHezi
Might be a bit big for what you want

Cheers,
Mark.

[stevie]

I haven't tested this yet at all on a runner but there is an incredible spark:
jetandturbineowners.proboards.com/thread/1450/st-50-build?page=3

I completely removed the ground electrode of a non resistor spark plug down to the face of the plug. The spark is insane.
From the notes:
Buck - set to 12.65-12.8 v input, output current put a jumper wire on outputs and set to 2.3-2.4A per buck instruction manual. Output V 4.0v. 1000 uF cap on buck output.

-edit - I may have to slip some braid over the wire if there is too much noise we will see.

--and edit again
Cool castings. We are casting all kinds of stuff here! Recently we have all these 3d printers running as well! Some of our stuff:

www.mesple.com/sculpture
www.mesple.com/mesple-technology-art

My shopmate does all this welding and casting and whatnot. I do the embedded systems/power/interactive etc.

Steve

[slittlewing]

Hi Steve,

I have done countless tests with different ignition modules and managed to make a really good working circuit without a spark gap, and I can also vouch for the NGK surface discharge plugs which work well and are inexpensive. I think these are the closest thing to engine ignitor plugs but much more friendly thanks to their standard HT lead connection and M14 thread.

The circuit I made worked perfectly on the bench but blew up the Hv module as soon as it was placed in a housing with close proximity to the capacitor! Must be down to EMI. I also back up Ben’s comment about using copper core wire.

Would be interesting to know how much those e2v gaps are if you buy one.

Cheers
Scott

[stevie]

Yeah my room mate made these we probably have some spark gaps around to try out. We are crazy here.
I showed him the little buck and transformer he kinda just raised his eyebrows smirked and walked away.

[monty]

Jan 29, 2022 21:33:21 GMT -5 stevie said:

I haven't tested this yet at all on a runner but there is an incredible spark:
jetandturbineowners.proboards.com/thread/1450/st-50-build?page=3

I completely removed the ground electrode of a non resistor spark plug down to the face of the plug. The spark is insane.
From the notes:
Buck - set to 12.65-12.8 v input, output current put a jumper wire on outputs and set to 2.3-2.4A per buck instruction manual. Output V 4.0v. 1000 uF cap on buck output.

-edit - I may have to slip some braid over the wire if there is too much noise we will see.

--and edit again
Cool castings. We are casting all kinds of stuff here! Recently we have all these 3d printers running as well! Some of our stuff:

www.mesple.com/sculpture
www.mesple.com/mesple-technology-art

My shopmate does all this welding and casting and whatnot. I do the embedded systems/power/interactive etc.

Steve

Hi Steve,

Cool stuff going on!

I've been in 3D printer upgrade hell. I've learned that I can do all the mechanical and wiring work in much less time than it takes to get the software configured! Good that you have someone to do that for you. Eventually I figured out that the code is open source, I am the quality control, the Chinese companies that make the boards randomly change chip sets, and there is NO version control and horrible documentation!! Once I figured that out I could get to the oh.....this is development not just buying a product that works state of mind. Got disgusted with the downloaded firmware (supposedly for my combo, which is pretty rare). Reasoned there would be less bugs in a more popular printer firmware. Downloaded that, and modified it for my printer. Eventually found a bunch of typos in the code. Found this just by looking at it long enough to understand the syntax and realize hey....why is that colon there? Finally got the darn thing working like it was supposed to and talking to the new touch screen (had to update that firmware too). Then I got disgusted with every single case for the control board I downloaded and printed (I've had it with "makers") They don't seem to understand maintenance, assembly or anything really. So I've been re-making everything in aluminum and bought a proper enclosure with a back plate to mount all the controls, adding cable chain so the the wires and leads aren't trying to destroy themselves. Nearing the end of this fiasco.

Not that it really matters, because the weather has not been suitable for casting anyway. I've got some other ideas for the ignition I'm working on. I should be able to try that out soon.

Monty

[monty]

Hi guys,

Finally got to do something related to the engine today. I tested out my new ignition idea. It's a Chevy LS2 truck ignition coil. These coils have an integral igniter. You just power it with 12-14V supply a 5ms square wave and it fires. Very compact, affordable, nice package. It already has high voltage and automotive grade terminals. Spark energy is about 50 mJ. If I had it to do over, I would use the IGN1A coil. They have about 100mJ of spark energy, and a more common spark plug terminal. But this is sufficient for now. I tried different firing frequencies from 1-70Hz. I think higher works better. I plan to use about 50 Hz (equivalent to 6000rpm). My test procedure was to completely wet the surface gap of the plug with WD40. Turn on the ignition, and spray directly with a stream of WD40. Not only did the plug fire right through the liquid, it would light the solid stream. I think that qualifies! Then I let it run for a couple min, until the plug was all covered with carbon and tried again. No problem blowing through the fouling.

Plug is a NGK BU8H surface gap. About $4.

The ECU can supply the square wave on the engine. For the combustion test rig I'll use a 555 timer circuit.

Monty

[andym]

Happy to help you with one of my ignition boxs, you can ask John about how good they are

[monty]

Mar 5, 2022 12:38:02 GMT -5 andym said:

Happy to help you with one of my ignition boxs, you can ask John about how good they are

Hi Andy!

I do appreciate the offer. I've been looking at other things. I have one of the HV generators and a microwave oven cap. I've also ordered the other bits I need. The only thing I can't seem to get my hands on is a spark gap tube. They are around $200 even from alibaba. I'm trying to put something repeatable and available together, not a one off. The turbine ignitors are also hard to come by, as are all the ignition wire bits for the shielded ignitor and wire.

I'm going to build one of the CDI boxes to test, but I plan on using this spark plug (if the testing goes well). It has a similar action to some of the turbine ignitors.

Stay tuned!

Monty

[slittlewing]

Hi Monty,

I have done a large amount of testing with different spark plugs and “voltage generators” and I can confirm there is no need to use spark gaps.

If you use a surface discharge plug (such as NGK BUE which are £2 each) you will have equivalent performance to an aircraft plug that is much more difficult and expensive to get hold of.

Using just a microwave cap and (optional) Diode, you can put considerable energy through these plugs. The addition of a spark gap is effectively just increasing the breakdown voltage and therefore energy, it is equivalent to putting two spark plugs in series.

Cheers

Scott

[monty]

Mar 9, 2022 17:40:54 GMT -5 slittlewing said:

Hi Monty,

I have done a large amount of testing with different spark plugs and “voltage generators” and I can confirm there is no need to use spark gaps.

If you use a surface discharge plug (such as NGK BUE which are £2 each) you will have equivalent performance to an aircraft plug that is much more difficult and expensive to get hold of.

Using just a microwave cap and (optional) Diode, you can put considerable energy through these plugs. The addition of a spark gap is effectively just increasing the breakdown voltage and therefore energy, it is equivalent to putting two spark plugs in series.

Cheers

Scott

Scott,

That's good to know. The inquiry I sent to a tube manufacturer here in the states resulted in a big long form stating that the tubes are ITAR restricted......never mind I can order them on Alibaba or buy them on Ebay! I guess the darn thing was used in some super secret radar back in the '50s and nobody bothered to change the status....good grief! There's nothing secret about a couple spheres in a glass tube!

Looks like I killed my first HV module. It started arcing internally.....I'd gladly pay more than $10 for one that would last a while. I guess there is a reason they come in packs of 5!

Monty

[monty]

Just a quick update on the spark gap. I received a quote today. $1275 set up fee and $875 per unit. This for a 2 in long glass tube with a couple metal spheres and an alpha source.....Available from Alibaba for less than $200.

I don't think I'll be using a spark gap! The rest of the components will be here Sunday.

I did do some more testing. With the truck ignition coil, the best results are had by using a regular spark plug with the electrode cut off. The specialty plug looks impressive with sparks flying everywhere, but it doesn't ignite the WD40 as reliably. Surface gap seems to need more umph.

I'll try to post some video of the plug testing when I get the new box put together and have some time.

Monty