"Fat Boy" 12/118 thrust engine

[turboron]

John, I received my YM5135FR Tachometer today. This is the one that Smithy sent you with the proximity probes. There were no instructions on how to set it up for a particular impeller. Do you or Smithy have any instructions or information?

Thanks, Ron

[racket]

Hi Ron












Cheers
John

[ripp]

Hello John,

Sorry for the late answer.

My thoughts are the following.

A turbo turbine wheel is not optimal for our turbines (Are also your words).

The turbine wheel TV94 is too small in diameter and flow range. The compressor wheel requires more power than the turbine wheel can deliver.

A jet engine is an open system and the constriction for the mass flow starts at the inlet to the turbine wheel. Because it helps little to clipping turbine wheel.

www.turbobygarrett.com/turbobygarrett/terminology

My preference is to keep the NGV Bladwinkel flat (for the force as the JU 2 has it) and also Use The back Side of the turbine wheel to increase the mass flow.





Maybe this will help

Cheers
Ralph

translate.google

[turboron]

John, thanks for the tach instructions. Please post your experience with the tach when you use it.

On Ralph's point, good practice to avoid flow separation when turning a flow path is to have an acceleration of the flow. In other words, a steady reduction of flow area throughout the turn.

Thanks, Ron

[racket]

Hi Ralph

Your turbine entry suggestion is like the mixed flow design , .................if only I had the space to experiment , but every millimetre of change at the turb wheel entry shortens my flametube by a millimetre.............compromises :-(

The Garrett document referencing clipping does only change flow area by 5-7% generally , the original Garrett turb wheel we use has a clipped exducer, its outflow angle is ~10 degrees greater than an unclipped wheel , this reduces gas deflection and horsepower produced , whether it actually reduces "efficiency" in the thermodynamic sense is debatable , I feel they are referring more to the efficiency in producing horsepower to drive the comp from a given pressure drop.

Most turbocharger turbine stages have too "efficient" a wheel for a jet engine , in that there is more gas deflection than is necessary resulting in swirl in the jetpipe .

Cheers
John

[nersut]

Hi John, it's very nice to read your & others builds. I have "secretly" (not logged in) visited this site frequently & read all the good progress in here
BIG thumbs up to you guys & good luck with the Fat Boy!

[racket]

Thanks :-)

[stoffe64]

Keep your head and your family in The shelter John, i understood that it passes a cyclone there which makes as much wind as your engine...

[racket]

Hi Stephan

Thankfully the cyclone is ~1,500 km further up the coast from me , we'll find out in the morning whether its a Cat 5 which will devastate huge areas with 240 kph winds or just a Cat 3 which won't be too bad other than dumping of 300-450mm of rain , that combined with very high tides at this time of the month and a 3 meter storm surge from the low pressure in the cyclone it'll create some severe flooding

Summer was a bit strange here , its was dry when it should have been wet , then as soon as March arrived we've had ~350 mm of rain in a week with horrendous humidity, I look rather enviously at you guys with your cold weather .

Finally got the last couple of bits for the 12/118 so should be ready for another test run soon :-)

Cheers
John

[bournaVee]

hi John,
i remember you mentioning trimming of the turbine wheel blades to "Chuks" when he was building his own engine. dont you think that might help you as well?

[racket]

It was severely clipped right from the start postimg.cc/image/4bmdneu9p/ , can't take much more off and still have some gas deflection through the exducer

[racket]

Hi Guys

Well I spent all weekend trying to get this new tach to work without success :-(

LOL,...... half a day trying to understand the chinese/english instructions on getting the 8 blade setting into its "brain" , that done, it was time to give the comp a flick around with the finger which resulted in the sensor flashing and some numbers coming up on the gauge ...........I was getting excited .............but it was short lived ...........as soon as the starter motor was fitted to its "spider" , the numbers stopped appearing, even without the starter being activated .

I kept fiddling around for the rest of the day without success , first trying one thing , then another and another etc etc etc.............:-(

Sunday came and I decided to power it up with 24 Volts instead of the previous 12 V to see if this improved things ................the only improvement was the lighting strength , finger flicking produced good results with a nice flash from the sensor as each blade passed by and numbers coming up on the gauge , but nothing once the starter was engaged and some serious rpm obtained .

The sensor was then screwed in a tad further so that it was within 0.010"- 0.25 mm of the blades , this didn't change things unfortunately .

I've ordered another gauge just in case my stumbling efforts to get this one going has damaged its "brain" ...............to be continued :-)

Cheers
John

[enginewhisperer]

Could there be an issue with the sensor body being grounded or something?

It might be shorting out via the starter wiring.

[racket]

I thought about that happening when on 12 Volts , but the 12 volt battery is separate to the 24 volt starter pack , I've got 3 X 12V batteries on the test stand because some things need different power levels and amounts of power , the 12V one only has "light duty", whereas the 2 X 12 V car batteries supply the starter on 24V , the oil pump on 12V from one of them and the fuel pump PWM on 24 V , LOL............its a "dogs breakfast " :-)

[enginewhisperer]

Have those sensors been used for turbo rpm before?

They might not be able to register at high enough rpm.