# Gas Turbine build, pictorial build log.



## rythmnbls

I thought the membership here might be interested in a pictorial build log of my current gas turbine project. The turbine is a 180N/40lbs thrust design by Gerald Rutten. Plans can be downloaded here http://members.tele2.nl/geraldensuzanne/turbines.htm . 

The engine presented here has some changes from the original design, the turbine wheel is larger, 75mm instead of 70mm, and the compressor wheel is a Garrett TO4E-54 instead of the Schwitzer 316954. 

Here is the link to the album on photobucket http://s87.photobucket.com/albums/k142/madluther/Turbine 2/

Slideshow of the above http://s87.photobucket.com/albums/k142/madluther/Turbine 2/?albumview=slideshow

Thanks for reading.

Steve.


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## blighty

40lb'er what are you putting that in? or are you just going to bug the neighbours with it ;D

interesting build, i wouldn't mind having a go at one my self, just need to find some inconel.

what ecu are you running with it and how is the NGV holding up? as in, are you getting any warping with the fins?


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## Swede

Lovely build, Gerald! I'm kind of surprised that gas turbines don't receive more attention than they do from "traditional" model engineers. They are absolutely fascinating to build and operate, and the power to weight is frightening... in fact, I've always found operating them a bit intimidating. You've certainly got to respect them.

They are a bit unique vs. any reciprocating engine in that if you give the latter more fuel and air, they accelerate, up to a point, but in the end, friction and forces win out and it becomes difficult to get more power out of them. Gas turbines, OTOH, give them more fuel, they suck their own air, keep accelerating, and the limiting factor usually becomes heat. 

Some of these smaller turbines turn at 160,000 RPM or more, and they'd happily turn 250,000 if they didn't get so hot they lose integrity under the immense forces at play. For all this, the fuel controller becomes a crucial component of any successful build.

Again, nice work!


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## rythmnbls

Thanks for the comments.



> 40lb'er what are you putting that in?



With the addition of a free power turbine stage it looks like (on paper) it will produce in excess of 40hp, so a lightweight motorcycle frame is the the most likely destination. Something like an RGV250 frame.



> what ecu are you running with it and how is the NGV holding up? as in, are you getting any warping with the fins?



This engine is yet to run although a similar NGV I have in another turbine doesn't warp at all, these NGV's are heated to red heat after welding and prior to final machining for stress relief.




> I've always found operating them a bit intimidating.



I agree, especially the first time I ran one on kerosene, the most stressed component of that event was me ;D

Steve.


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## petertha

Look forward to your build & lots of pictures. I think miniature turbines are an incredible feat of engineering effort. Ive been involved in RC a long time & I'm just blown away at how far commercial turbines have advanced - jets, heli's, turbo-props, boats & everything in between. But to make it yourself, and strap it to a bike, well thats just too cool!

I just finished reading 2 books, more history orientated: "Genesis of the Jet Engine" (Frank Whittle & the Invention of the Jet Engine) by John Golley. And "Not Much of an Enginee" (Sir Stanley Hooker Autobiography). Fascinating stuff.


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## blighty

> the most stressed component of that event was me Grin



with you there ;D

the first time i started my home build up i was jumping around like a little girl. think it was a case of OMG it works..... OMG!!! how big are those flames!!!

there is a guy doing what your doing on the GTBA, but as i haven't rejoined i don't know hows he getting on. any how worth a look if you a member.


Petertha.

just to let you know, Wren turbines are now given the plans for there MW54 away for free. i would post a link, but for some reason i cant get on the site. if you build it or not, it's still worth a look see.


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## gmac

http://www.wrenturbines.co.uk/mw54-turbo-jet-and-turbo-prop-second-stage-plans

 thanks blighty, I've been looking for a set of turbine plans! And thanks for posting Steve, I'll be following your progress with interest.

Cheers Garry


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## rythmnbls

> there is a guy doing what your doing on the GTBA



That's me ;D same engine.

There isn't much activity on the GTBA these days so I thought I would post the links here. Hopefully the photos will show that the more difficult parts, ie the turbine wheel and NGV, are quite manageable in a home shop. The material costs for those parts were less than $50, much less than the commercially available parts. Hopefully that will inspire a few more HSM'ers to give it a try 

Steve.


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## blighty

that's you is it on the GBTA? as i said i was following you then my member ship run out (don't think i will rejoin). i remember thinking when you announced what you was going to do with it..... i thought you bloody nutter!! (that's in good way )

yes, turbine parts are very expensive. i looked in to making another MW54 and just to buy the parts you cant make would of cost £800. i mean £112 for a fuel pump. really, what is it? a 280 motor and 2 little gears. 

i don't think it will encourage more home builders until the stigma of turbines dies down and people begin to realise there not all that.


flame suit on for my last comment.


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## Tony B

I love the sound of a turbine, 

Nice work on yours,amazing what you can do in your shed


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## Swede

The big money items for a home-built GT are the bearings, the compressor, and the turbine wheel. The latter two for a beginner are best purchased at least as a casting for the turbine, as materials and geometry make or break a design in many cases. Anyone who creates their own turbine wheel, compressor, or guide vanes, certainly has my respect.

I agree that the fuel pump costs are a bit silly. The pump head can be machined by anyone with decent tools and hands, and the motor itself only costs a few $$.

A gas turbine project deviates from steam or IC in that it generally has a LOT more sheet metal work, welding, and soldering, vs the latter. Sheet metal work can be intimidating... it did me, until I found it really wan't all that tough. When my first MW-54 ran, it was exhilarating, and also a bit scary, as mentioned.

TORCHING is never fun. Torching is the burning off of excess fuel during a start, a very fuel rich mixture. This really doesn't hurt so long as a lot of air is kept moving through the engine, but 2 meter roaring flames don't look really good. One problem I have had is torching from my turboprop. Because the engine is "backwards" relative to the intake (the intake is at the rear of the engine), it torches towards the operator during a wet start. Trying to remain calm while pinned in place by two roaring jets of flame is tricky!  ;D


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## blighty

> it torches towards the operator during a wet start. Trying to remain calm while pinned in place by two roaring jets of flame is tricky



i can see how that could put a downer on your day.

not doing the one up bit, but i had flames coming out both ends of my turbine once. that was definitely a "WTF" moment. i think that's what melted the inlet cone :


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## Swede

blighty  said:
			
		

> i can see how that could put a downer on your day.
> 
> not doing the one up bit, but i had flames coming out both ends of my turbine once. that was definitely a "WTF" moment. i think that's what melted the inlet cone :



Oooooh, that's bad.   Obviously you had some sort of compressor stall. Did the compressor wheel survive?


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## blighty

i'll try and make this short ;D

 the starting instruction in the building notes for the '54 are a bit vague. it basically says, turn the glow on then the gas, spin the turbine up to about 9000 rpm. when the turbine slows down you should here a popping noise. at this point give it some with the starter. (well that's how i interpreted it anyway)

this i did, but when ever i gave it some it blow the flame out, so the temp would never get to the point where the ecu would kick in (@102deg) and start the fuel pump. so when the flame blow out i would take the start motor away and the turbine would slow down. when it got to the 800rpm mark it would then relight, i would then think "we're off" so i would put the motor back on and it would all happen again...... every time i did this the temp was slowly increasing, until the point where i had the flame out at about 98deg. i then took the starter motor away, like i had before, but this time when it lite the temp went above 102deg and the fuel pump kicked in. i now have a turbine at 800rpm,ecu chucking more fuel in and the turbine slowing down. flames then shot out the back of it and when the turbine got to 0rpm flames started to come out the front as well. i shut the turbine off with the Tx and turned off the fuel valve, flames then stopped coming out the front so i could spin it up and blow the flames out........ i should of used the fire extinguisher, but Oh Well never mind.

only damage was the rear of the inlet cone, that was made out of nylon. when i spoke to wren about it they said why did you make it out of nylon? 'cos it says so on the plans. no no says wren, you should make it out of ali, 'cos the nylon one melts and goes out of shape........... well i know that now : any thing else i should know that you haven't put in the plans????


well it all works now and the eurofighter its going in will be here any day soon ;D ;D ;D


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## Swede

I can see it all in my mind...  

I built an early MW-54 from plans, and my cone was turned from delrin - I haven't had any problems like yours, but such things are ECU related as much as anything else.

Back then, there were few electric starters. Guys would start turbines with air, lots of it. I took an old leaf blower and turned it into a "GSU", a ground start unit, by adding a flexible duct, and a piece of 3" PVC with a 90 degree el, and the face that mates with the engine, I shaped so as to fit well and deliver a lot of air. I noticed I could very reliably start the engine and the temps were low, nice and low.

Then I fitted an electric motor start, and went through a period of time trying to make it work. It did, but the temps were always 300+ degrees higher than the air start. I took the electric start off and revived the GSU, and have never gone back. Being able to control and deliver, as needed, huge volumes of cold air, has saved my butt more than once.

I'd say more than 50% of the jet engines out there, full scale, use air for start, not electric motors. Usually it's an internal APU blowing air, sometimes it's an external cart. I'll admit a hand's-off electric start is cool, but I do prefer air. Even if you do electric starts, it might be a good idea to have air on hand for problems like torching, or hot starts.


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## doubleboost

Hi
Steve.
That is some fantastic work you are doing there.
I have built a few gas turbines (using turbochargers)as the core
Not quite modells but small scale
This is how we start them
[ame]http://www.youtube.com/watch?v=IND3eAI3YZk[/ame]
[ame]http://www.youtube.com/watch?v=am8P-OleztQ[/ame]


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## blighty

bloody ruddy hell and holy crap to boot. that was brill!!!

any tips on how to that with my eurofighter ;D ;D ;D


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## rythmnbls

Minor update.

There are a few more photos that have been uploaded to the Photobucket site.

Here is a sample.

Rolling flanges on one of the CC rings.









> I have built a few gas turbines (using turbochargers)as the core



I love that AB, it looks like it lights fairly reliably, thats an achievement in itself.


Steve.


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## doubleboost

Thanks steve
After burners are fun
I am just modding turbos
What you are doing is simply amazing :bow: :bow: :bow:
John


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## rythmnbls

Work on the combustion chamber is progressing, I still need to finish welding the front CC ring to the outer wrapper, and make up the spacers that fasten the CC to the diffuser.

A shot of the parts prior to welding.





A shot of a test assembly, here I am checking the clearance between the diffuser and the combustion chamber in order to get the sizing for the spacers that mount between these components.





There are more photos showing details of building the CC uploaded to the Photobucket site.

Thanks for reading.

Steve.


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## doubleboost

Very nice
Steve
A bit of a black art hole patterns on flame tubes :bow: :bow: :bow:
Watching this thread with great interest
John


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## Sparticusrye

Very nice progress, I'll be watching this post with interest. I wanted to build one but haven't got to it yet. Seeing your progress has renewed my interest.

James


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## rythmnbls

Update.

The combustion chamber welding is done. The vaporiser tubes are done and installed. 

Photo here.






A start has been made on the plumbing, the lube line is done. 

Photo here. 





Photo of the major parts so far ..





Next up are the fuel supplies and the outer case. Then it will be time to start thinking about a test stand.  ;D

As always, there are a many more photos at the photobucket site.
http://s87.photobucket.com/albums/k142/madluther/Turbine 2/


Steve.


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## Herbiev

Great build log Steve. Lots of pictures. Definately worth a karma point


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## blighty

it's coming along 8)


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## rythmnbls

Thanks for the karma point Herbie, I'll put a Coopers in the fridge for you 

Today saw the fuel ring completed, not my favorite part to make, very fiddly plus the engines performance can be greatly affected by a bad ring.

Photo of punching holes for the injector needles, the holes are punched rather than drilled to avoid filling the ring with swarf. The ring is supported by the grooved tool to stop it flattening out during the punching.







Testing the fuel ring after brazing the needles.







Photo of the fuel ring installed on the combustion chamber showing the routing of the feed pipe. It is important that the feed pipe avoid covering any air holes. I still have to make the clips that secure the fuel ring to the combustion chamber, the ring also needs to be cleaned of brazing residues. 






Thanks for reading.

Steve.


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## Herbiev

Hi Steve. I do love a cold Coopers. Will save it for the christening of the engine which doesn't seem too far off now.


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## rythmnbls

The outer case is done, it is made from 316 stainless sheet 0.5mm / 0.020" thick. Its basically a flange and an outer wrapper spot welded together.

Here's a photo of the parts.





Photo of the setup used to hold it together for welding.





The case after welding





Photos of the case fitted to the engine.











I still have to make the pre-heat gas line, the front compressor spinner with an embedded magnet and drill and tap the case securing holes. After that I need to think about balancing in preparation for some test runs.

Thanks for reading.

Steve.


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## blighty

still looking good, neat job with the case.

what balancing method are you using?


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## Herbiev

Steve. Superb bit of workmanship there. Can you tell us a bit about your spotwelder please. :bow:


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## steamer

Nice build!

I don't mind saying I love the sound of a turbine, but frankly scared of the top speed....Lots of forces in a very small package!

Thanks for taking us along!

Dave


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## rythmnbls

Herbie,
 The spot welder is a commercially made unit from Hobart model # HSW-15.

Blighty,

 Up until now I have only statically balanced my turbines, but this one will need something better, I'm looking at a few designs published by the GTBA at the moment, no firm plans yet.

Regards.

Steve


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## blighty

statically balanced... as in "the wren way"?

i to was looking for balancing stuff on the GBTA, that's why i joined. the only thing i could really find was plans for the frame/mechanics, but not much on the electronic side of thing. plus there was nothing about the software needed to run the thing. i was a bit miffed at this as the GBTA have a nice balancing machine on there bench at all the engineering shows they go to, with a sign that says "you can make this, details on the GBTA web site" don't know if its me or not, but i cant find a single all in one build thread.... i.e build the frame with these drawings, make the electronics here's the schematics and download the software to run it here.

when i balanced my turbine i went the wren way. tried and tested method i'm sure, but i'm not 100% convinced in it. not so much the idea, but me doing it..... yes, it now stays put when you rock it, but is it REALLY balanced?


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## mu38&Bg#

There should be some mention of the Dynams balancing software on GTBA. I used it when building my spindle and can say that it's worth buying. It's not exactly cheap, but if you intend to use it more than once, it's doesn't really cost much.


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## blighty

the only software i did see was about £200, ok if your doing more than one, but not if your just doing one.


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## blighty

just been doing a search for Dynams balancing software..... and i found this http://users.atw.hu/aerotarget/Balancing/Balancing.html

looks good, but unless i missed something, nothing about pricing :-(


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## H Pearce

Hi all, i don't post here much.....ever, never seem to have any thing to add till now!
I came across this site some time ago.
Free plans for a dynamic balancer..... and no software required, not quite as flash as the last link but should work fine for just the rotor.

http://www.technologie-entwicklung.de/Gasturbines/Balancing_Tool/balancing_tool.html

Hope it is of some help

H


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## mu38&Bg#

Dynams doesn't need a frame, but can be used with one. You just mount accelerometer sensors to your engine or whatever. That's why I decided on the software. By the time I made the balancing rig, the circuitry, with a motor to drive it, it would have cost much the same. I've had Thomas's design saved on my computer for a decade and never built it. I probably would have if I was more involved in electronics. Thomas's pages on the little KP-31 turbine got my gears turning and I bought the compressor wheels long before I had any machining tools. now I just have to get around to building it. He was involved in the Lambert Kolibri design using this compressor.

Just send. Mr. Koncz an email for Dynams pricing. There are two options.

Greg


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## AdShea

What are you doing for bearings, lube, and cooling? I see three notches at the front of the shaft tunnel and you've got one lube line coming in. Are the others for bleed air cooling? Where does the oil return?


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## rythmnbls

> I see three notches at the front of the shaft tunnel and you've got one lube line coming in. Are the others for bleed air cooling?



Yes, this is standard practice these days.



> Where does the oil return?



The lube system is like a 2 stroke engine, the fuel consists of a mixture of kerosene and 3-5% of a synthetic two stroke oil. The bleed air and fuel mix create a lube mist which cools and lubricates both bearings, the mist exits the rear bearing and is lost. There is no return. Lube rate is very low, one or two drops per second.

The bearings are preloaded full complement hybrid ceramic ball bearings.

Regards.

Steve.


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## AdShea

Thanks Steve for the info. I've been trying to read up on these and there's some info that's hard to find in the gap between the "slap a combustion chamber on a turbocharger" crowd and the "build a real one" crowd. Your build looks amazing and has awesome fit and finish.


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## rythmnbls

The photo below shows the final machining operations on the case, and the diffuser. Although it's just a simple drilling job, the setup is not.







The diffuser has 13 wedges so a dividing head is needed to space the holes accurately, additionally only 6 of the wedges are used for the retaining bolts. The result is a fairly odd drill pattern. The masking tape was used to mark the wedges to be drilled, as drilling the wrong wedge would scrap parts that take many hours to make. So, after about 3 hours of fiddly setup the holes have been drilled ;D

Regards,

Steve.


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## rythmnbls

A minor update.

The glow plug mounting boss has been machined and welded to the combustion chamber. A start has been made on getting the test stand ready.

Photo of the test stand.






I still need to make the gas pre-heat supply line, the compressor spinner / nut needs to be replaced with a unit that has an embedded magnet and the rotor still needs to be balanced.

Thanks for reading

Steve.


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## rythmnbls

Apart from balancing, the engine is finished.

Photo of the all the parts.





Photos of the assembled turbine.









It looks like I will have to build a dynamic balancer next, until that is complete the engine will be statically balanced for initial ( low speed ) test runs. The plan is to run it next weekend, and take some video 

Steve.


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## Herbiev

Looking great Steve. Cant wait for the videos


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## JorgensenSteam

I think I would wrap it in about 6 layers of Kevlar.
If one blade lets go, or the bearings give out, then it will all go, and those blades will go through anything and everything.

Just a thought.


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## rythmnbls

I ran the engine for the first time today, not a lot to report as this was just a propane run.

The engine self sustained at 10K rpm, which I'm happy with. Unfortunately my propane regulator wont allow higher speeds so faster runs will have to wait till I'm ready for a kerosene fueled run.  

Here is a very brief clip of the run, you can hear the engine flame out when I accidentally cut off the propane. You can see the NGV is glowing a bit, I'm guessing at 10K rpm there's probably not enough airflow to cool it adequately. Normal idle speed is 33k.





There was some slight distortion of the NGV during cool-down which caused the turbine wheel to rub, a couple of minutes in the lathe took care of it.

Photo of the combustion chamber after the run.





A photo of the rear end after reassembly





Mechanically it looks good so I hope to post a video of it running on kerosene soon.

Regards.

Steve.


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## doubleboost

Hi
Steve
Looking good
The burn pattern is in the correct place on the flame tube
More gas and it would have been away
John


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## blighty

she's alive ;D ;D


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## steamer

Nice one Steve!  keep at it!

Dave


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## steamer

Nice one Steve!  keep at it!

Dave


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## Herbiev

Very impressive Steve. I love it :bow:


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## Boxfordian

Hi Steve

Good work ! Am following on the GTBA site anyway, but thought I'd say 'Hi' here too, small world aye ! 

Ray ;-)


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## ozzie46

That is just way to cool!!! Thm: Thm: Thm: Thm: Thm:

  Ron


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## rythmnbls

Thank you all for the kind words.

Hi Ray !, small world indeed 

The first run on kerosene was attempted today, the result of which I would call a partial success. The attempt was aborted just as the turbine was coming up to speed due to a tachometer failure, it seems to be getting interference and giving lower than normal readings. I need an accurate tach for testing, so for safety's sake I shutdown when I realized the readings weren't accurate.

On the plus side the turbine itself seems good.

Here's a video of the run, at 1:15 was when it was decided to shutdown, I'm estimating RPM at this point is about 15-20k (the tacho is reading 7k), the flames are normal and usually disappear as rpm increase and approach idle speed.





Thanks for reading.

Steve.


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## rythmnbls

There were some discussions earlier in this thread regarding balancing and balancers, I ended up building the balancer published by the GTBA. If you have access to the site and the GTBA CD, you can find the schematics in newsletter 34 published in 2001. This is a standalone device, no computer or software needed.

Photo of the balancer electrics.





Photo of one of the sensor arms. The red material is 1.6 mm fiberglass. The piezo sensor is 20mm in dia.





Photo of the setup, visible on one of the blades is a small piece of rubber hose used to create an imbalance point for calibration.





Rather than build a dedicated frame for balancing, I used the lathe. The thinking is the balancer hardware needs to be rigid, be able to absorb vibrations and be level. The lathe fits that bill better than anything I could build, so it got the job, plus I would only have to make the sensor arms.

Hopefully this answers some of the questions raised earlier.

Regards.

Steve.


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## rythmnbls

Been a while since I've updated this due to an unexpected health problem that laid me up for a month.

Engine testing is progressing, initially I've been concentrating on getting exhaust gas temps (EGT) down to reasonable levels. The first couple of runs EGTs were around 720 degrees C which is at least 100 degrees too high. The cause was traced to case leaks and a rubbing compressor wheel both of which have been addressed.  

Testing methodology has been to run the engine at a set speed starting at 35k rpm, burn a full tank of fuel ( 500ml ), shutdown and inspect critical parts, increase speed by 5K rpm and repeat the entire test. Maximum speed attained so far is 50K rpm.

Here's a video clip of the test at 45K rpm.
[ame]http://youtu.be/fUZqlS1nt_w[/ame]

The start was a bit hot as the starter, a dremel, was removed too early forcing the turbine to work harder than necessary to get up to speed, plus I was a bit heavy handed on the fuel control. 

Another ( very blurry ) clip showing the arduino displaying RPM and EGT for the 50K run. The temps displayed here are about where they should be, so I'm pleased with progress so far.



 

Thanks for reading. 

Steve.


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## rythmnbls

Here's a clip of another test run, top speed was 55K RPM, this clip will give interested viewers an idea of fuel consumption of these engines. They are very thirsty.

[ame]http://youtu.be/C6BHWNTmCd0[/ame]

Regards,

Steve.


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## rkepler

Impressive work.  What do you intend to take the top speed to?


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## rythmnbls

Thanks for the comment.

Top speed with the existing turbine wheel is about 60K, this wheel is made of inconel 625 and isn't strong enough for a full speed run which is about 115K, I have a slug of inconel 718 and plan to use that for a replacement wheel, but I don't have the tooling to slice it up yet, plus I need a temp controlled oven to heat treat it. The tooling and the oven are side projects that are in the works, but finding the time is always the challenge 

Regards,

Steve.


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## petertha

rythmnbls said:


> I ended up building the balancer published by the GTBA. ...This is a standalone device, no computer or software needed... Steve.


 
First off, what a great accomplishment on the turbine!

Re dynamic balancers, Ive looked at some web links & aside from the basic mechanics of how the shaft is spun & sensors mounted, almost all the rest is above my head! 

- when you detect an imbalance, how do you then go back to the appropriate (radial) position in order to alter the mass at the right spot? Do you orient or register the shaft assembly in some manner beforehand somehow?

- how do you determine the amount of mass change to 'fix' it into balance?

- would this balancer be confined to reletively small amounts of imbalance like your turbine & teeny manufacturing differences, or could it somehow be adapted to typical combustion engines to tune crankshaft counterweight running assemblies?

- is the rpm level itself somthing that factors into correcting balance, or do you arrive at the same correction recipie by just spinning it at some safe, arbitray rotation amount?

fascinating stuff!


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## rythmnbls

> First off, what a great accomplishment on the turbine!


Thanks Peter, much appreciated.



> - when you detect an imbalance, how do you then go back to the  appropriate (radial) position in order to alter the mass at the right  spot? Do you orient or register the shaft assembly in some manner  beforehand somehow?


I will attempt to explain how this is done.

As you probably can see from the photos previously posted, the balancing rig consists of two fiberglass arms one of which has a piezo sensor attached. The electronics consists of a piezo signal amplifier with 6 sensitivity settings, a zero crossing detector, and a strobe circuit. There is also a variable DC power supply used as a speed control for the motor that spins the rotor under test. The balancer is equipped with a meter that measures the amount of imbalance detected by the sensor.

A typical balancing session session starts by spinning the rotor in the rig, increasing the speed of rotation until a resonance point is reached, the resonance point is indicated by a peaking of the signal observed on the meter and the stability of the static image of the rotor created by the strobe. The wheel to be balanced will have previously been marked at regular intervals around its circumference. Here is a photo of the compressor wheel with a set of markings.







Once the resonance speed has been determined, the speed of the rotor is not changed for the rest of the procedure.

At this point we don't know where the imbalance point is. In order to locate it an additional weight is introduced, usually by adding a small amount of putty or plasticine to the wheel in an arbitrary location. If the position of the additional weight does not coincide with the imbalance point the static image generated by the strobe will shift either to the left or the right. The number at the top of the wheel is noted, the test weight is moved 90 degrees and the test repeated and the new number at the top of the wheel noted. This test is repeated twice more so that the test weight has been tried at 4 cardinal points around the wheel and the four resulting strobe numbers noted. These four strobe points will typically all be on one side of the wheel, the center of these strobe points will be very close to the actual imbalance in the wheel. The test weight is now placed at this center point and the strobe image shift is compared to the strobe image when the weight is removed, by moving the test weight left or right in small increments it should be possible to find a location where the strobe image no longer shifts when the weight is added or removed, this is the imbalance point.

To determine how much material to remove the test weight is moved 180 degrees from the heavy point, more putty is added (or removed) until the signal strength on the meter drops to zero.  Material can now be ground off the heavy point in very small increments, and a corresponding amount of putty removed to re-balance, this is repeated till no putty remains and the wheel should theoretically be in balance. All of the above assumes that there is only one heavy point on the wheel, this is often not the case, smaller imbalance points often exist, if so, the whole procedure is repeated at a higher sensitivity setting on the piezo amplifier.



> - would this balancer be confined to reletively small amounts of  imbalance like your turbine & teeny manufacturing differences, or  could it somehow be adapted to typical combustion engines to tune  crankshaft counterweight running assemblies?


It might be possible to adapt it to crankshaft balancing, I think it would be a matter of setting the right amount of sensitivity in the amplifier and finding an appropriate resonance speed. 



> - is the rpm level itself somthing that factors into correcting balance,  or do you arrive at the same correction recipie by just spinning it at  some safe, arbitray rotation amount?


The rpm used on the balancer is determined by the natural resonance of the rotor and the sensor arms. This is the point that the rig produces the best signal for the balancer electronics.

Disclaimer ! 
There are probably other and better ways to balance these rotors, I'm no expert, this is just one method. ;D

Again, thanks to everyone for all the kind words and hopefully my explanations are clear enough to understand.

Regards,

Steve.


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## Noitoen

:idea:  I would imagine that, if you connect a 2 channel oscilloscope with one channel to the piezzo amplifier and the other to reference point, you could pinpoint the unbalance location much faster. It may just be my imaginationscratch.gif


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## rythmnbls

Oscilloscopes have been used to balance these rotors but they suffer from the same limitations as the dedicated balance detector, i.e. the signal from the piezo does not directly match the imbalance point of the rotor. The reason is the the signal generated is not just from the rotor alone, but is the resonance from the spinning rotor and the sensor arms combined, this is why the procedure outlined above is used.

Regards,

Steve.


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## starnovice

Steve, this is awesome!!!  Your machining is also very neat and well done.  I noticed the web page that has the plans for this turbine says it is not a beginner project.  Do you have suggestions for how to get started in building turbines?

If there were still karma points I would sure give you one so please accept a virtual karma point.  th_wav

Thank you
Pat


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## rythmnbls

Thanks for the comments Pat, very much appreciated.

To get started there are a couple of books I'd recommend, the first is "Model Jet Engines" by Thomas Kamps, the second is "Gas Turbine Theory" by   H. I. H. Saravanamuttoo, G.F.C. Rogers, H. Cohen and Paul Straznicky. Both can usually be found on Amazon, the second book is expensive, but is very detailed.

The Kamps book includes plans and instructions for an engine that these days is considered outdated, a good starter engine is the KJ-66, a forgiving and well tested design, you can find plans here. http://www.pulse-jets.com/phpbb3/viewtopic.php?f=6&t=1179

Regards,

Steve.


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## builderofstuff

I'm new to the group and this is my first post, but I just wanted to take a second to say thanks for posting the links to the plans as well as your build pictures. I've had an interest in homebuilt turbines since about 1996 and that interest was what first inspired me to buy my lathe. Seeing how you approached some of the construction steps was really informative. I used to be a member of the GTBA myself, but let my membership lapse a number of years ago. 

Chris


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## rythmnbls

Hi Chris,
 Welcome to the forum and thank you for your kind comments. Seems we both got into machining for similar reasons 

Most of the construction techniques I used were pioneered by GTBA members so I cant take full credit for all of them, but, if I can be of any help if you are building a turbine just let me know.

Regards.

Steve.


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## builderofstuff

Thank you very much for the offer. I currently have the FD 3/64 book, the Kamps book which I think is the first edition, the gt2000 plans, the mw54 and turboprop plans which I bought as soon as they became available, the wasp h20 plans, the kj66 plans, and now the two you linked to. 

One of the things about your build that I was really excited to see was the turbine wheel you made. It was really nice to see a built wheel rather than the cast inconel wheels that most folks use. Ive always wanted to make a turbine without having to use cast parts.

Chris


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## rythmnbls

> One of the things about your build that I was really excited to see was  the turbine wheel you made. It was really nice to see a built wheel  rather than the cast inconel wheels that most folks use. Ive always  wanted to make a turbine without having to use cast parts.


One of the goals of this build was to take a cheap compressor wheel bought on ebay and adapt the GR180 design to suit. That entailed re-designing the diffuser and designing and building the NGV and turbine wheel to match. This also meant that the engine could be built for very little cost. I bought a 6"x6"x.08" sheet of inconel from McMaster for around $45
 and was able to make two wheels from it, one for my Kamps and one for this project. Unfortunately that same sheet is now about $60, but that is a lot cheaper than a cast wheel. On the plus side, McMaster now stocks Inconel 718 sheet in that same size which is a much better choice should anyone consider making a wheel. 

I have the first two books you mention but I would recommend getting a copy of Gas Turbine Theory by Cohen and co if you really want to understand the design process. Its the reference I used to do most of the design work for this project.

Regards,

Steve.


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## builderofstuff

Have you ever compared the basic design outlines in the Kamps book with other sources? There's a section in the book where he gives some basic equations to use to modify his design to use different compressor wheels. Just wondered if you had ever checked any of those. 

Chris


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## rythmnbls

> Have you ever compared the basic design outlines in the Kamps book with other sources?


Yes, I compared it with the Gas Turbine Theory I mentioned earlier. The Kamps book will allow you to scale his design to suit other comp wheels but it does lack in detail in some areas, although, plenty of successful homebuilt engines have been based on his book. Personally, I prefer the Gas Turbine Theory book.

Another good resource is this forum. http://jetandturbineowners.proboards.com

Regards.

Steve


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## builderofstuff

Thanks. I appreciate the info.

Chris


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## builderofstuff

Speaking of the Kamps book. I used to have a spreadsheet that I think came on the gtba CD that had the design formulas. Wish I knew what happened to that CD.

Chris


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## builderofstuff

I found it. Whew, figured I had it backed up somewhere. 

Chris


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## fabinho

Hello Steve I've downloaded your design and I've already begun to build the GR180 is already very advanced, now I would like to know if you can provide me with the project and condigo source of fadec with Arduino?


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## rythmnbls

> Hello Steve I've downloaded your design and I've already begun to build  the GR180 is already very advanced, now I would like to know if you can  provide me with the project and condigo source of fadec with Arduino?


Hi fabinho, Thanks for your comment. The GR180 was not designed by me, the original designer is Gerald Rutten.

The arduino project I used with my GR180 is not a FADEC, it is a combined tachometer, temperature guage and glowplug driver. I'd be happy to post schematics and the code if you're still interested.

Regards,

Steve.


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## fabinho

Hello Steve I'm interested to know if you could post I really appreciate. [email protected]


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## rythmnbls

Hi fabinho,

Here are the schematics for the arduino board and for the RPM sensor.

The arduino board




The RPM Sensor board




I'm not sure if the max6675 module is still available, but this is a replacement http://www.adafruit.com/products/269

The arduino code...



		Code:
	

//--------------------------------------------------------------
//
// Interrupt driven sketch to measure RPM, and Temps
// it expects a suitable signal on pin digital 2 / external int0
// Display is via LCD.
//
//--------------------------------------------------------------
#include <LiquidCrystal.h>
#include <max6675.h>
#include <Wire.h>

int thermoDO = 3;
int thermoCS = 4;
int thermoCLK = 7;

MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);

LiquidCrystal lcd(13, 12, 11, 10, 9, 8);

uint8_t degree[8]  = {140,146,146,140,128,128,128,128};

int pwmPin5 = 5;    // 976hz signal on pin 5, connected to a mosfet to drive a glowplug.
int dutycycle = 80;    // 25 = 10% duty cycle

volatile  word rpmcount;

unsigned long rpm;

unsigned long timeold;

void setup()
{
  pinMode(pwmPin5, OUTPUT);
  analogWrite(pwmPin5, dutycycle);    //turn on the glowplug output. 
  
  
  lcd.begin(20,4);              // Setup the LCD, use 16,2 for a 16x2 LCD, etc.
  lcd.clear();                  // start with a blank screen
  lcd.createChar(0, degree);
  
  attachInterrupt(0, rpm_fun, RISING);  //enable int0

  rpmcount = 0;
  rpm = 0;
  timeold = 0;
  
  delay(500);
}

void loop()
{
  lcd.setCursor(0,0);
  lcd.print("RPM: ");
  
  lcd.setCursor(0, 2);
  lcd.print("EGT:");
  
  lcd.setCursor(5,2);
  lcd.print(thermocouple.readCelsius());
  lcd.write((byte)0);
  lcd.print("C ");
  
  if (rpmcount >= 100)
  {
    //Update RPM every 100 counts, increase this for better RPM resolution,
    //decrease for faster update

    rpm = 1000000*60/(micros() - timeold)*rpmcount;
    //rpm = (micros() - timeold);
    timeold = micros();
    rpmcount = 0;
    lcd.setCursor(5,0);
    lcd.print("      ");
    lcd.setCursor(5,0);
    lcd.print(rpm);
  }
  delay (500);
}

void rpm_fun()
{
  rpmcount++;
  //Each rotation, this interrupt function is run
}

//-----------------------------------------------


If there are any questions, let me know

Regards,

Steve.


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## fabinho

Hey thanks Steve, my good friend, I am very grateful to you.


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## fabinho

le capteur de régime est optiques ou magnétiques ? a comme poster ce détail dans spiner ?


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## fabinho

the RPM sensor is magnetic? How is the built-in magnet have any specifics?


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## rythmnbls

Yes, the RPM sensor is magnetic.

The spinner nut has 2 rare earth magnets like these, http://www.kjmagnetics.com/proddetail.asp?prod=D31 

The spinner nut was built using this as a guide. http://www.5bears.com/magnut.htm

Regards,

Steve.


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## fabinho

Once again many thanks Steve.


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## jimjam66

doubleboost said:


> I have built a few gas turbines (using turbochargers)as the core
> Not quite modells but small scale
> This is how we start them



Words fail me!  It's one of those points in life where your brain says "run away from those scary insane people" while your heart says "God, what I'd give for a few laps of Brands on that thing with the afterburner howling".


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## fabinho

Hi Steve, I have a doubt on a circuit of componeten RPM. It is unclear what would qualify that called the 5v line to ground? and the 10uF tantalum capacitors can be replaced by other types of capacitors?
att.


----------



## rythmnbls

Hi fabinho,



> Hi Steve, I have a doubt on a circuit of componeten RPM. It is unclear what would qualify that called the 5v line to ground?


Are you referring to the SS495 hall effect device ? If so perhaps this link will clear things up.  http://www.digikey.com/catalog/en/partgroup/ss495-series/12446 My circuit uses the SS495A device.


> and the 10uF tantalum capacitors can be replaced by other types of capacitors?


Any 10uf capacitor can be used, they are just bypass caps. I just prefer tantalum caps.

Regards,

Steve.


----------



## fabinho

Not Steve mean that circulated


----------



## rythmnbls

That's just another bypass cap, 0.1uf, preferably a monolithic ceramic, but any cap will do.

Regards,

Steve.


----------



## fabinho

Thank you for the clarification Steve.


----------



## fabinho

Goodnight Steve. I chose to buy a Linear Magnetic Sensor Module For Arduino (LM393 Hall Sensor Module for Arduino ). I would like to know if you help me in the program by changing it to use with this sensor? and in which the Arduino pin should I use?


----------



## rythmnbls

fabinho,

Do you have a link  to schematics and specifications of this sensor board ?

There should not be any changes needed to the arduino side if this sensor board produces a TTL compatible +5v signal and has the equivolent magnetic sensitivity of the the original design.

Regards,

Steve.


----------



## fabinho

OK Steve. I managed to make the change. Thanks for the attention.


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## fabinho

good afternoon Steve in the search I did not find succeeding and stuff that you used to make the nozzles have you tell me what material used and what are the measures?


----------



## rythmnbls

Fabinho,

The reason there are no nozzle drawings is I never drew them. There didn't seem much point in making nozzles until testing of the turbine section was completed.
When I get the new turbine wheel and NGV completed I will start on the nozzles.

Regards,

Steve.


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## fabinho

Good morning Steve as the load balancer that you did, it worked well. I'm thinking of building a, too, would like to know from you if he needs some specific program if you have with you send me more details. grateful Fábio


----------



## hvirtane

This thing looks really amazing. 

There are a couple of really basic things I wanted to know. 

1) 
Could methane used as the fuel to run this engine? 

2)
Are there any plans available how to build gas turbines to run with much slower rpm and still get an affordable efficiency?


----------



## rythmnbls

hvirtane said:


> This thing looks really amazing.
> 
> There are a couple of really basic things I wanted to know.
> 
> 1)
> Could methane used as the fuel to run this engine?
> 
> 2)
> Are there any plans available how to build gas turbines to run with much slower rpm and still get an affordable efficiency?



Sorry for the late reply, I'm just home from a sudden 10 day hospital stay.

I don't see any reason to not use methane as a fuel. Gas turbines run on just about any hydrocarbon. The appropriate precautions for containing the methane would be the biggest drawback.

I've seen a build of a 2:1 scale up of an FD3/64 on the GTBA forum. This engine self sustained at about 1800 rpm and last I heard had been test run up to ~22k rpm.

Regards,

Steve.


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## fabinho

good afternoon Steve. right where you live the inconel is facio acquisition? because where I live I couldn't still find so I had to do my all stainless turbine.


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## rythmnbls

I buy inconel 718 from http://www.onlinemetals.com Look under the Nickel / round rod section.

Regards,

Steve.


----------



## fabinho

rythmnbls said:


> Hi fabinho,
> 
> Here are the schematics for the arduino board and for the RPM sensor.
> 
> The arduino board
> 
> 
> 
> 
> The RPM Sensor board
> 
> 
> 
> 
> I'm not sure if the max6675 module is still available, but this is a replacement http://www.adafruit.com/products/269
> 
> The arduino code...
> 
> 
> 
> Code:
> 
> 
> //--------------------------------------------------------------
> //
> // Interrupt driven sketch to measure RPM, and Temps
> // it expects a suitable signal on pin digital 2 / external int0
> // Display is via LCD.
> //
> //--------------------------------------------------------------
> #include <LiquidCrystal.h>
> #include <max6675.h>
> #include <Wire.h>
> 
> int thermoDO = 3;
> int thermoCS = 4;
> int thermoCLK = 7;
> 
> MAX6675 thermocouple(thermoCLK, thermoCS, thermoDO);
> 
> LiquidCrystal lcd(13, 12, 11, 10, 9, 8);
> 
> uint8_t degree[8]  = {140,146,146,140,128,128,128,128};
> 
> int pwmPin5 = 5;    // 976hz signal on pin 5, connected to a mosfet to drive a glowplug.
> int dutycycle = 80;    // 25 = 10% duty cycle
> 
> volatile  word rpmcount;
> 
> unsigned long rpm;
> 
> unsigned long timeold;
> 
> void setup()
> {
> pinMode(pwmPin5, OUTPUT);
> analogWrite(pwmPin5, dutycycle);    //turn on the glowplug output.
> 
> 
> lcd.begin(20,4);              // Setup the LCD, use 16,2 for a 16x2 LCD, etc.
> lcd.clear();                  // start with a blank screen
> lcd.createChar(0, degree);
> 
> attachInterrupt(0, rpm_fun, RISING);  //enable int0
> 
> rpmcount = 0;
> rpm = 0;
> timeold = 0;
> 
> delay(500);
> }
> 
> void loop()
> {
> lcd.setCursor(0,0);
> lcd.print("RPM: ");
> 
> lcd.setCursor(0, 2);
> lcd.print("EGT:");
> 
> lcd.setCursor(5,2);
> lcd.print(thermocouple.readCelsius());
> lcd.write((byte)0);
> lcd.print("C ");
> 
> if (rpmcount >= 100)
> {
> //Update RPM every 100 counts, increase this for better RPM resolution,
> //decrease for faster update
> 
> rpm = 1000000*60/(micros() - timeold)*rpmcount;
> //rpm = (micros() - timeold);
> timeold = micros();
> rpmcount = 0;
> lcd.setCursor(5,0);
> lcd.print("      ");
> lcd.setCursor(5,0);
> lcd.print(rpm);
> }
> delay (500);
> }
> 
> void rpm_fun()
> {
> rpmcount++;
> //Each rotation, this interrupt function is run
> }
> 
> //-----------------------------------------------
> 
> 
> If there are any questions, let me know
> 
> Regards,
> 
> Steve.



Good afternoon Steve, I made here a circuit as shown in your drawing to the glow plug more when I turn on the 12v Battery candle call and is still making connected do you have any idea what it could be?


----------



## bpd115

It is with a heavy heart that I must say my friend Steve passed away last week.  He was unlike anyone I have ever met and I am blessed to have worked with him for a number of years. 

I would often show others this thread and videos of the turbine he built as a testament to his brilliance.  I remember when he told me he was undertaking this project I didn't even think things like this were possible to do, let alone in the shed in your backyard.

When I first met Steve I asked him what flavor of Linux he ran.  His answer, "My own". I knew at that moment I had a ton to learn from him, and I did.

So tonight let's have a shot of Wild Turkey and raise our glass to a hell of a guy.

RIP my friend.


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## fabinho

My GOD. too bad I'm sorry from the bottom of my heart. Is a not telo between us grief. Can you tell us how this tragendia happen?


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## bpd115

Unfortunately he had been battling cancer for a bit.


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