"Fat Boy" 12/118 thrust engine

[racket]

Hi Stephan

At the moment I don't know what P2 I will have at what RPM , but once the engine is running at its full potential I can do a set of P2 vs RPM numbers and check if they are "ballpark" with my assumptions as to how I hope it will perform .

Using a hand held tach is awkward , so once those numbers are taken I won't need to use the tach anymore , I'll simply refer to the P2 and keep max power below a certain P2 point.

Theres no way I'll be overspeeding the engine as both the comp and turb are capable of another 20% rpm without compromising safety.

Cheers
John

[racket]

Hi Patty

LOL......I'm working as fast as I can whilst still maintaining my usual standard of attention to detail , nobody wants to see this engine fire up more than me :-)

Cheers
John

[racket]

Hi Patty

Starter motor all wired up and tested today , ~17,000 starter rpm on 12 volts , just need to finish connecting the lube supply to the engine and I can do a trial spoolup to see how many engine rotor rpm the starter can produce once the air loads are applied.

And just because I wanted to , I activated the ignition and fed a bit of start gas into the engine to check if it'd catch fire , it did in the normal way , so thats another things ticked off the list ..........heh heh , then I repeated the process just to make sure , it was nice to hear and smell some fire in her belly :-)

Its looking good for first spoolup sometime next week .

Cheers
John

[smithy1]

Mar 18, 2016 2:42:39 GMT -5 racket said:

Hi Patty

Starter motor all wired up and tested today , ~17,000 starter rpm on 12 volts , just need to finish connecting the lube supply to the engine and I can do a trial spoolup to see how many engine rotor rpm the starter can produce once the air loads are applied.

And just because I wanted to , I activated the ignition and fed a bit of start gas into the engine to check if it'd catch fire , it did in the normal way , so thats another things ticked off the list ..........heh heh , then I repeated the process just to make sure , it was nice to hear and smell some fire in her belly :-)

Its looking good for first spoolup sometime next week .

Cheers
John

That free-running 17k rpm should equate to ~10k under a bit of load....should be fine.

I'm excited for you John..!

Cheers,
Smithy.

[racket]

Hi Smithy

Did some starter testing today.

Oil pressure 70 psi .

12 volts with nil oil pressure produced ~7,000 rpm , with oil pressure ~6,000, good airflow from the exhaust .

Finger flick with full oil pressure produced several revolutions so none of the 10/98 engine's stiffness.

Will need 24 volts , so off to get another battery tomorrow .

Cheers
John

[smithy1]

John,
You may well find the rpm will increase with a bit of help from the engine itself, as soon as she lights off, you'll get plenty of turbine assistance. I know the 6041 does, with just the blower and 70psi oil pressure, I'm lucky to see 6,000rpm....but as soon as the fire is going, the rpm's come up real quick. I'd give it a try with the 12v first and you may well be surprised.

Cheers,
Smithy.

[racket]

Hi Smithy

Heh heh , already purchased the new battery by the time I read your email, so now with 24 volts I've got ~10,500 rpm with full oil pressure , and a very good breeze exiting the engine from the extra pressure buildup from the 75% increase in rpm , now at 17.5% N1 , a bit of fuel should push it up to 25-30% and over the hump to a successful spoolup :-)

Got all the batteries , 3 of now ,on their respective chargers to top up ready for more testing , 2 car batteries in series for just the starter motor and another dry cell job for all the ancillories so theres no worry about voltage drop affecting them.

I'll keep you posted

Cheers
John

[smithy1]

Mar 22, 2016 2:58:34 GMT -5 racket said:

Hi Smithy

Heh heh , already purchased the new battery by the time I read your email, so now with 24 volts I've got ~10,500 rpm with full oil pressure , and a very good breeze exiting the engine from the extra pressure buildup from the 75% increase in rpm , now at 17.5% N1 , a bit of fuel should push it up to 25-30% and over the hump to a successful spoolup :-)

Got all the batteries , 3 of now ,on their respective chargers to top up ready for more testing , 2 car batteries in series for just the starter motor and another dry cell job for all the ancillories so theres no worry about voltage drop affecting them.

I'll keep you posted

Cheers
John

Yep...That'll work for sure. 30% should see it way over the hump for sure...assuming ~60k-ish maximum..?

When I ran the 6041 last weekend and she "flamed-out", it dropped down to ~14-15K rpm....After she "re-lit" and with me watching the EGT....I let her go and she was still able to recover to 23k without getting hot, only went to an indicated ~680c during this time and then settled to the normal high 400's at idle like normal....I was actually quite surprised at that.

I would've though she would just bog down and get hot....your flame tube must be real good then..!

Cheers,
Smithy.

[racket]

Hi Smithy

Yep , 60K max ................heh heh , until I want to explore the "envelope"

LOL, you really know how to get the GT6041 to work , the atomisation at idling settings must be pretty good for her to accelerate away from such low rpm without help from a starter, always nice to hear about "abberant" running conditions that workout well , it expands the knowledge base .

An update on the 12/118 with fully charged batteries ...............another 1,700 rpm from previous best to 12,200 rpm with 70 psi oil pressure , the 10/98 engine achieved ~13,000 rpm under similar conditions , the slightly lower rpm is easily accounted for by the 40% bigger inducer area of the 12/118 flowing a lot more air that is sucking power from the starter .

As a direct comparison I'd say the 12/118 is in a better position than the 10/98 engine for a successful spoolup , the 12/118 comp is ~16% bigger in the exducer diameter so more tip speed as well which would be sucking power .

Yeh , she's ready

A few pics










And the camera battery is being charged up

Cheers
John

[smithy1]

Excellent work John....I'm sure it'll work fine....as usual.

That battery charger you have on the left is "exactly" the same as one I have at home..go figure..!

I have a spare 044 pump at home, do you need one for this engine in the future??

Cheers,
Smithy.

[racket]

Hi Smithy

First spoolup attempts ended without success :-(

It sounded like it was "there" , but on removal of the starter, rpm decayed, it wasn't "over the hump" , might need more starter power.

Video is "piss poor" , just my arse and some flames coming out the engines exhaust , it doesn't show anything .

I checked rpm of the engaged starter at end of start attempts and only ~9,500 rpm , so batteries starting to fade after a few attempts , starter very hot to the touch , its been working hard.

OK , time to put it away in the shed and think on it , no more attempts until after Easter , got too much to do .

Cheers
John

[ripp]

Hi John

great work of mechanical Engineering but

Turbine wheel too small for the large compressor wheel (45% more compressors opening opposite TV94)and...

my modest opinion

I am very curious about your next steps

Cheers
Ralph

translate.google.at

[racket]

Hi Ralph

Yep ,she looks good , BUT , theres issue with the turbine wheel being mutilated making it less efficient at power production , and the fact its a bit marginal with its inducer diameter compared to the comp , but I feel its more to do with starter power , the engine did accelerate nicely once the kero was fed in , but not enough rpm to get over the hump to self sustain .

I've been doing some research on starters and it appears from the graphs I've looked at that power starts to drop off badly when they're "over revved", theres a "sweet spot" where revs are at say 50% whilst Amps are high .

I don't know a lot about starters so it looks like I'm in for some tuition if I want to sort this out ............where are the electrical engineers when you need them :-).

My initial thinking is a speed up gearbox on the starter to increase the coupling speed whilst keeping the starter rotor at modest rpm .

I'd like to be able to produce a 30,000 rpm output shaft to the starter whilst keeping its rotor to ~6-8,000 rpm , so a 4 or 5 :1 stepup gear, I might go and have a chat to my local auto electrician to checkout his thoughts.

Just a minor hiccup ............not the first , I'll get it going hopefully ;-)

Cheers
John

[pitciblackscotland]

Hi John,
Bugger I was at Andrews place on Sun we done some test starts on the bike, that stater you sent down works out you think one of those motors would do the job ?

Cheers,
Mark.

[Johansson]

Bugger about the starter problem, but I know that you will overcome it.