VT-50 Jr. Dragster (kindof)

[Feathers]

Hey Everyone,

Feathers Here, Just wanted to start a thread folowing the build of my Holset VT-50 based afterburning jet dragster.

The engine is nearing an operational state, with the basic subsystems being polished, and an evaporative fuel system underway.

I am 17, which means that school is out in 3 days, and I can REALLY start cranking away at this project ;D. 17 also means that I'm relatively naiive, which is why I'm posting on this forum!

All you DIYGT guys have been a huge help to the development of this project, and I'm sure that your top-notch advice will help me make the most of this project!

Heres a link to my Build Blog:
workshopchronicles.blogspot.com

And a link to my youtube channel:
www.youtube.com/highvoltagefeathers

Take a look, the blog will be kept current, and I'll post pictures and updates, and questions on this thread as well.

Here goes something...

[Johansson]

Welcome to the forum!

The engine is coming together nicely, are you going to buy a JR dragster frame for it or build one yourself?

That mill you bought will sure come in handy for many years to come, I went the same route myself when I was just above 20 (I am 30 now) and bought a lathe, mill and tigwelder instead of spending the pile of cash on a car or snowmobile. Never regretted that decision.

The best part is, when you are tired of the jet thrust you can build a power turbine for it and get some serious HP!

Cheers!
/Anders

PS. It would be easier to follow the thread if you pasted the blog posts here so everyone can easily see what has been done up until now. DS.

[racket]

Hi Feather

Welcome to JATO ....................keep building the Thread , summer holidays should provide time for some serious construction .

Yep , we'll be here if you need a bit of advice and encouragement :-)

Cheers
John

[Feathers]

Heres a video of my progress with the engine so far.



I've also updated my blog, as I'm begining work on the evap system, so take a look!

www.workshopchronicles.blogspot.com

Any criticism welcome, I need input!

Thanks everyone.

Feathers

[Johansson]

Really nice time lapse video Feathers! I see you got your long sleeved shirt on half way through the welding, got a nice tan on the left arm the next day? ;D

I did that myself once, mag welded a turbo manifold for my brother in a t-shirt for an hour and could peel the skin off my arms a couple of days later...

Nothing to say about the engine except that it looks sweet!

[Feathers]

I suppose that little news is good news from the expert! ;D

[Johansson]

I noticed one thing on your youtue video of the old turbine, you say that you had a bearing failure on it and I think I know why.

The oil outlet port must be pointing towards the ground and not angled like in the video, oil pools up inside the housing and that ruins the function of the journal bearings.

[Feathers]

That would be part of the problem, but most of the problem was the fact that there was no oil pressure from my agricultural pump, and it was actually gear lube, because thats all I had at the time I was 14, and EXTREMELY eager to get it running! The flame tube only ran half the length of the combustor, there was no lubricant cooling whatsoever, and the flexible exhaust tubing I used as a combustor air line leaked about half the output of the compressor.

Feathers

[Johansson]

Ok, that might explain the bearing failure.

When I built my first gas turbine I didn´t know that a turbo actually needed oil pressure, I thought the bearings were similar to the brass bearings in my fathers lathe where a drip of oil now and then would be enough.

Good thing I never got that engine up to idle revs. ;D

[Feathers]

Hey everyone!

I'm about to start on my flametube!

How do I decide on total hole area, (factoring in the main evap tube area) and how large/where the holes go? any input is welcome!!

Feathers

[racket]

Hi Feathers

Use the Jetspecs programme on DIY , the evaporator tube crossectional flow area is counted as part of primary air hole area .

Checkout the RoTs on DIY for more info .

Cheers
John

[wolfdragon]

the jetspecs program from www.ivcity.com/turbosoft/ will help you figure that out

the positions are .25-.33%, 50%, 75% of flametube length (rough locations, like with grenades - close is good enough)

play around with hole sizes to get nice numbers of holes, and deburr the edges for better flow characteristics

[Feathers]

I've used jetspecs, but say I wanted to go with a tried and proven "area", and layout.

The guys at badbros racing, and several others I've seen used a fairly short, fat combustor. Mine is much more slender, and the flow characteristics (because of a direct, rather than tangential allignment of the combustor inlet, meaning that the air is not going to be spinning in my combustor) will be rather different.

However, The hole pattern of these short, fat combustors (the hole pattern on the badbros site) is already fairly "optimized" as far as organization, and the area matches up exactly with the inducer area on my VT-50.

If I were to adapt this pattern to my longer, skinnier 4" flame tube, would it be sufficient?

Thanks!

Feathers

[racket]

Hi Feathers

4 inch flametube .................OH !!!!

What is your inducer size ??

What fuel will you be using??

What fuel distribution method will you use ??

Evaporators or spray nozzle if kero/diesel ??

Skinny flametubes give problems due to high axial air speeds in the primary zone .

Cheers
John

[Feathers]

Hey John!

3 inch inducer size (7.01" inducer area)

Diesel, Kerosene, Jet-A, even vegetable oil if I am confident eanough to try it .

One 1" evap tube, 6" in length, which trees into three 3/4" tubes that turn 180* twoards the front of the combustor.

Evaporators with a holow-cone type spray nozzle

Ooh.......... Could I do anything as far as arranging the holes in the primary zone, or moving some of the primary hole area to the secondary and tertiary zones to slow things down?

Thanks!

Feathers