HX 82 102/255 " Money Pit "

[Deleted]

Hi Guys

Mock up of oil pump and motor.... for scale the bolt at the side is M8 x 40

[elventu]

I have a question about the shaft tunnel, not only this but all of the ones I see in the last days (I'm silently reading a lot of threads of the forum, since I can't walk, at now) are made of aluminum.
Why?

It seems to me more obvious that materials with less heat expansion coefficient are the best to use, you have a long shaft made of a material with little heat expansion in a long tube with high temperature, there isn't the risk that the shaft tube expands more than the shaft, locking it?
Why not using cast iron or steel for the tube?
They can have even the same mechanical strenght with a lighter design...?
Ehere I'm wrong?

Davide

[stoffe64]

Hello Davide
No risk of that,because you have oil flowing thrue it taking the heat away and if it would expand it expand from the shaft mostly.
Cheers/Stephan

[Deleted]

Nov 11, 2018 12:36:49 GMT -5 elventu said:

I have a question about the shaft tunnel, not only this but all of the ones I see in the last days (I'm silently reading a lot of threads of the forum, since I can't walk, at now) are made of aluminum.
Why?

It seems to me more obvious that materials with less heat expansion coefficient are the best to use, you have a long shaft made of a material with little heat expansion in a long tube with high temperature, there isn't the risk that the shaft tube expands more than the shaft, locking it?
Why not using cast iron or steel for the tube?
They can have even the same mechanical strenght with a lighter design...?
Ehere I'm wrong?

Davide

Its not some thing i have given much or any thought, but I am not aware of any one having issues with locking up engine because of expansion. Issues like this would engineered out :-)

Aluminium is easier to work with, easy for some to cast, mine is all billet CNC. Not sure how cast iron machines, and perhaps if we used steel for shaft tunnel,
there could be issues with aluminium ( perhaps 80% ) of the engine expanding at different rates to the steel shaft tunnel.

Good question, others mite have a different view

All the Best
Andy

[elventu]

It was only a doubt I had.
Thank you!

[slittlewing]

Good video on the flame tube size for people wanting to make one!! Can we see a cad render/cutaway of the complete new engine?

Cheers

Scott

[racket]

Hi Davide

As Andy said , alloy is easier for us to make the part from , but if we wanted an engine that was expected to last for tens of thousands of hours, then a cast iron/steel shaft tunnel would be "better" as it'd cope with wear from rotating bushes , though with pinned non rotating bushes an alloy shaft tunnel would be OK .

Our shaft tunnels are only ~80 mm long , even with a 100 C degree difference between shaft material and tunnel material there'd only be ~0.08 mm of length to be concerned about , the only place where that would affect axial clearances is at the turbine wheel where it'd increase our shroud clearance by a tad , all turbines run very generous clearances because the wheel always expands faster than the surrounding material during spoolup , so that 0.08 mm would be very easily taken care of as it only represents maybe 12-15% of the design clearances at the hot end , both front and back of the wheel need enough axial clearance to cope with all eventualities.

Cheers
John

[elventu]

Thank you John!
It's only a doubt, being a lathe machinist maybe I'm used to work with steel without seeing problems working with it.
To me it seem "strange" the choice of aluminum because I don't love machining it (but I'm used to work anticorodal alloys, ergal and avional are much better to machine), and I was thinking why not on steel.
But now I understood that there's no problems with it!

Thank you!

[elventu]

Sorry for my english, I know it is bad. 😑

[racket]

Hi Davide

I did make a steel shaft tunnel for my FM-1 engine jetandturbineowners.proboards.com/thread/576/fat-lady-fm-1?page=1 , but for following engines I went to alloy to not only make construction easier but to save a little bit of weight as well .

Cheers
John

[Deleted]

Nov 11, 2018 15:24:49 GMT -5 slittlewing said:

Good video on the flame tube size for people wanting to make one!! Can we see a cad render/cutaway of the complete new engine?

Cheers

Scott

Hi Scott they are already up, earlier in the tread and a animation of the engine

Here

jetandturbineowners.proboards.com/thread/1025/hx-102-255-money-pit?page=3

And Video



All the best
Andy

[monty]

Andy,

Been following your updates. Great work!...keeps me going. Soon, I'll start on my flame tube..

Monty

[slittlewing]

Nice one cheers mate, forgot about that!! What holds the flame tube in situ?

Bet you cant wait to get assembling!!

Cheers

Scott

[Deleted]

Nov 12, 2018 8:28:11 GMT -5 slittlewing said:

Nice one cheers mate, forgot about that!! What holds the flame tube in situ?

Bet you cant wait to get assembling!!

Cheers

Scott

I will post a picture, but there a 9 bolt in tabs one the end of the NGV...

So the oil system.... AS a ESC for the brushless motor it ahve been suggested i use one of these. Not your standard ESC



Link to the site

vesc-project.com/Hardware

Not this version but an earlier type..... the thing can be programmed its self, ports on board for expansion, so much.
Perhaps some of you guys that are good with all this stuff mite like a look.
I am hoping we can use it to some how help maintain a self controlling oil system, as the oil thins it will ramp up it speed ?
I am not over keen on micro thing on my build, hard to fix at the side of the track. But I am getting some help from guys that build battle bots using these
If they can with stand impacts the deal with, they should be OK for my project

[enginewhisperer]

I have used VESCs in a couple of things, and they're a vast improvement over the usual RC brushless controllers.