# Gas turbine



## geoff_h (Feb 12, 2012)

Hello, this is my latest project after the opposed 4 cyl 4 stroke. Its a small gas turbine based on a design called a Kj66. The bearings, compressor, turbine wheel and starter motor where purchased everything else was made. The compressor is 66mm diameter. It self sustains at 22000rpm idles at 34000rpm and tops out at 120000rpm. The normal exhaust temps are 450-650c. There is about 17lbs of thrust at full power. It starts on propane using a regular rc glowplug. This is used to heat the combustion chamber so it can vaporise and run on kersoene or Jet A mixed with oil. There is a tee in the fuel line that feeds oil to the bearing tunnel at a ration of about 30:1. Full power it burns 10oz/min. The starter is a 400 size brushed motor with a custom made bendix.The first runs where done using a homeade hall effect tach and ran directly from a 30lb propane tank. Kerosene was added with a simple speed controller running a fuel pump. It is now running on a Fadec system that monitors the temp, speed and controlls the fuel pump, gas solenoid and starter motor. It controls everything from startup to cool down and only requires a throttle signal. This system is needed so I could install it into a rc plane. It has almost 6 hours runtime now.

This is a video showing the autostart sequence. There are other videos from the first runs showing airstarts on my youtube account.

[ame]http://www.youtube.com/watch?v=9uwnrapNFs8[/ame]

Geoff


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## geoff_h (Feb 12, 2012)

The combustion chamber is made from 0.015" 316 ss. The end caps are spun on the lathe then spot welded to the inner and outer wrappers. A spot welder was made using a transformer from a microwave that had the secondary winding replaced with 6ga battery cable. Most of the parts are 6061. The fuel lines and distrbution ring are 2.5 and 4mm brass. The fuel is injected into the chamber through ss tubess that have a .023" ID. They are all silver solidered. The two bearing are ceramic ball full compliment angular contact. I first tried preloading the bearings using a coil spring and a bushing in the back of the tunnel. This system proved insufficent as there was enough forward force on the rotor to cause the front bearing to unload and cause damage. This was replaced with wave washers behind the front bearing. The last pic shows a download from the fadec.


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## hi speed scrap (Feb 12, 2012)

Well done! I have often been tempted to build one myself, only as an engineering challenge, as I dont fly r/c planes. only heli's.
And the kits are a fair cost as well.

Congratulations


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## Harold Lee (Feb 12, 2012)

Geoff - Looks like you have an Arduino Mega as the controller. I have used Arduinos in a number of designs from a model enterprise bookshelf for my grandson to an automation of a small home brewery but NEVER to control a jet engine!!! Great job!! Keep us posted on your progress...

Harold


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## jpeter (Feb 12, 2012)

Nice stuff. Did you buy the compressor wheel? If you did, what is it?


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## geoff_h (Feb 12, 2012)

jpeter  said:
			
		

> Nice stuff. Did you buy the compressor wheel? If you did, what is it?



I bought the compressor. The plans call for a KKK5326 2019, The one I used is the same size but has a differnt radius on the blade shape not sure what the part number is though. 

Geoff


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## agmachado (Feb 12, 2012)

Hi Geoff,

Very nice job !!!

Cheers,

Alexandre


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## Billzilla (Feb 13, 2012)

Very nice job.
Have you ever built a jet engine out of a turbo? I've thought about it but the problem of getting an old & big turbo at the right price hasn't happened yet and I'm not sure how to design the combustion chamber.

That FADEC would make life a lot easier for you as well. Auto-start and monitoring the EGT during acceleration & deceleration, etc.


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## geoff_h (Feb 14, 2012)

Billzilla  said:
			
		

> Very nice job.
> Have you ever built a jet engine out of a turbo? I've thought about it but the problem of getting an old & big turbo at the right price hasn't happened yet and I'm not sure how to design the combustion chamber.
> 
> That FADEC would make life a lot easier for you as well. Auto-start and monitoring the EGT during acceleration & deceleration, etc.



I have never built one from a turbo. The combustion chamber design is what makes the engine. I have never designed my own but from what I have read getting a stable flame that burns evenly without overheating the chamber is very tricky and every small detail plays into how it burns.

Harold it is a Mega. I built the tach using it. It was my first attempt using such a device but has alot of possibility. I have another project started with it that can measure airspeed, alt, battery voltage underload and g force. I just have it made up on a board and have not made a propper circuit. One day like to finish it.

Have it installed in a plane now. With a little luck I can run it for a while without having to do any work on it. Although I have never left anything alone for that long without modifying somthing.

Geoff


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## vcutajar (Feb 14, 2012)

Geoff

Very nice model of a gas turbine. And it also sounds like the real thing. What sort of combustion chamber are you using, annular or canannular?

Vince

p.s. Just had a look a the pictures again and it looks like an annular combustion chamber.


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## geoff_h (Feb 14, 2012)

It is a annular chamber. As far as I know these are the only type that have successfully been used on this size of an engine. It has 6 injectors and the air flows into the combustion chamber though the inner diameter as well as the outer diameter. The picture show the chamber from the rear looking foward. The fuel is injected from the rear into 6 sticks that run lengthwise towards the front of the chamber

Geoff


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## vcutajar (Feb 14, 2012)

Thanks Geoff for the info.

You said in your first post that the EGT is 450 - 650 C. Is it 450c at idle thrust and 650c at full thrust? Excuse my curiosity, but I am just comparing figures with the commercial jet engines.

Vince


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## geoff_h (Feb 14, 2012)

The highest temps are normally during startup and acceleration. Startup will see 550 -590, accel can be 600 or higher depending on the current rpms, Idle is about 500, full rpm is 570 and in the mid range rpms the temps are the lowest arround 450. When I was playing with the tailcone my first attempt had an opening of about 48mm and the temps where in excess of 700. I opened the cone in stages and got to 52mm and the temp was 550-570.

Geoff


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## Soldier9 (Mar 7, 2017)

Hi Geoff. Am new here. Am interested  in building a rc turbine ecu using the arduino. I already have  and arduino kit uno. Can you send me close or pictures  of your ecu so I can see how to wire mi we up. Or send me a drawing  or something  of that nature to help  me make my connections.thanks in advance. Or if anybody here can help me.


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