New to jet building, not new to jets. :D

[brady93]

Hey guys

I've been scrolling through this forum lately, so i thought i would sign up.

First off, i would like to introduce myself. My name is Brady, i am 19, and i am from Tasmania, Australia. I am currently a first year apprentice as an aircraft maintenence technician, specifically helicopter turboshaft engines. I have been involved with RC airplanes and boats for as long as i can remember, and love to tinker with engines.

Just recently i've started thinking about building my own turbine. My goal is to build an axial turbofan engine with 200lb of thrust (obviously that will not be my first project).

I've bout myself a lathe and a mill, i have only basic lathe and mill skills that i learn't in grade 12. I built a double acting steam engine, as well as some other bits and pieces.

I intend on buying some books in the next couple of weeks to start my reasearch before i start building. I am fully aware of the risks involved with such a dangerous hobby.

I have sourced a Rajay turbo from work for my first project. I have the dimentions here i will post them up when i have more time. the bearings and seals are stuffed, so i intend on only using the compressor and turbine wheel.

I signed up to source and share information with other enthusiasts.

So my first question to start off with:

Are there any rules of thumb that go with building a turbine? I know this is a broad question, and any information or links would be great.

I look forward to following the active projects on this forum, and learning as much as i can.

Regards
Brady

PS: I am aware it could take me years and years to reach my goal.

[brady93]

So here are some dimentions of the turbine and compressor wheel i have.

Compressor:

76mm diameter (larger end)
56mm diameter (smaller end)
22mm depth

The turbo houseing says 0.63 in large text on the front.

Turbine:

79mm diameter (larger end)
62mm diameter (small end)
21mm depth

I've got other measurements of the wheels and shaft.. etc.. But thought there was no point posting them at this stage.

I've spent some time looking over some plans, like the K66 etc.. I am interested in building a turbine of my own design for a first project, but plan on using some of the key fundamental sections from existing and proven designs (such as the K66), to increase the likelyhood of it self sustaining.

Can i do this without too much trouble?

I've noticed in some of the threads that people have mentioned formula's and other rules of thumb for building combustion chambers... etc... Does anyone have any they can post up?

Also, for my axial research i've seen someone mention blade angles, can anyone link me to some more information on this?

I've been sifting through the threads on here most of the week extracting information.

Cheers
Brady

[brady93]

This section of the forum seems a bit quiet???

Nevertheless, at work we have an Allison 250 turboshaft engine that is pulled down. I am planning on taking some measurements of the combuster and scaling it down. If my small copy of the combuster is successful, i will post the dimentions on here incase someone wants them for there own project. The turbine this combuster is out of is found in the Bell 207 Jetranger.

The combuster is mentioned here:
http://www.users.zetnet.co.uk/gas/combust.htm

Cheers
Brady

[metiz]

Hey Brady

Yes, this forum has been dying a slow death for a while now, which is unfortunate. If you want some help with your turbine, go to http://jetandturbineowners.proboards.com/index.cgi

[Bounce]

Hi Brady,
as Metiz said, you should check out the JATO-Forum, you will recognise many threads there

Also you can check out the DIY-Turbines mailing list on yahoo:
http://tech.groups.yahoo.com/group/DIYGasTurbines/

The layout is a little bit oldish, but there is an incredible amount of info on that group. They also have a rules of thumb section and so on (most notably a great tool called JetSpec).
Most members seem to focus on the "easier" route to just hook a CC to a turbo but really all sorts of engine can be found there...

The two books about homemade model turbines by Kurt Schreckling might be worth a look too (especially the first one, the second one about freepower turbines, while still worth reading, is not as good in my opinion)
Also there is a book about homemade turbines by Thomas Kamps with a good amount of formulas, pics of commercial units, rules of thumb etc.
And last but not least google should turn up a lot of university or research papers on different subjects if you search for the right thing...

Your compressor wheel is around the size of Ash's T04 build and my current build, so you might get some 110-130N (25-30lbs) out of your turbine

Do you plan on using a radial or an axial turbine in your build?

Of course the exact data of your compressor wheel would be needed, but this might give you a rough direction of what to expect for your diffusor plate:



cheers,
Dennis

[brady93]

Hi Dennis!

Thanks very much for the info. I will sift through it and get back to this forum when i have more questions, or when i start building.

Cheers
Brady

[racketmotorman]

Hi Brady

I just sent you a PM about us Aussie builders ................all the best with your project

We'll help out where we can

Cheers
John

[brady93]

Got your PM, thanks John.

[brady93]

Unfortunately, i will need to get a bigger lathe before i can start building. I've ordered Thomas Kamp's book, so i will read through that and start designing my turbine.

My lathe at the moment is only very small, for very small scale stuff etc... So i will be upgrading shortly. And recommended lathes available here in Aus?

Cheers
Brady

[racketmotorman]

Hi Brady

For turbine work we need a large diametric swing on our lathes for machining flanges etc , we don't need large centre distances , 900mm is adequate , I've found the 15 inch -375mm swing on my lathe is big enough for what I've been making
Theres some very good lathes available at very reasonable prices , check Ebay .

Cheers
John

[brady93]

Hi John

I've been digging through Ebay regulary to see what's available. Thanks John!
15 inch? Thanks, that gives me an idea as to what size i need.

Cheers
Brady

[racketmotorman]

Hi Brady

A 15 inch diameter swing will allow construction of 12 inch diameter cased engines without too many problems , I've even turned up the 14 inch dia wooden pattern for the front cover over a Garrett TPE 331 comp wheel thats ~10 inch diameter

Cheers
John

[brady93]

Perfect!!! Thanks John!!!

Cheers
Brady