"Fat Boy" 12/118 thrust engine

[enginewhisperer]

yep, even though a nicely running engine is a great stress reducer - it's no good if you overdo it getting to that point.

Fingers crossed for some good test results

[azwood]

Nice work hmmmm that would fit in a bike frame

[azwood]

Sept 1, 2019 17:53:36 GMT -5 enginewhisperer said:

that looks excellent

Stainless can certainly be a bit of a pain to weld. It helps to back purge it all with argon, but it's tricky on a part like that and uses a lot of gas.


Will you pipe fresh air into the gap on the other side of the "screw" panel to help cool the bearing tunnel?

Tig welding stainless is that way to go can't beat it purging is nice too makes it flow much nicer inside I did work on a milk plant we had to purge every pipe to prevent contamination inside.

[racket]

Hi Aaron

Sure would with a bit of a stretch .

The interstage ducting could be shortened a few inches by moving the slipjoint closer to the gas producer and having the thermocouples and P4t pickup in the freepower section rather than the "jetpipe" as they are at present .

Cheers
John

[racket]

Hi Guys

The freepower mounting for the stalled torque testing is progressing , just about got it finished , a couple more support stays and a bit of exhaust pipe to add .

A few progress pics









Cheers
John

[azwood]

Is that a load cell of some kind at the end of the arm kant tell.its great to see the fb is getting there what power figure do you think you'll get lol that has to go in something for sure.ill be keeping a close watch for inspration.

[racket]

Hi Aaron

LOL.......yep, a low tech spring balance, the 2 foot long arm simply pulls down on the spring balance , its a ~25 kg balance , so if I can see 20 kgs on it I'll be happy , thats 44 lbs at 2 feet , so 88 ft lbs of torque , mutiplied through a 4.36:1 gearbox gives me ~384 ft lbs of torque at the output sprocket , with a 1:1 ratio to the axle and an 11 inch dia kart tyre ( 5.5 inch radius ) it'll produce , 384 X 12 div 5.5 = 838 lbs of "thrust" between tyre and road , with a slightly larger axial sprocket it'd be very easy to get the magical 1,000 lbs of "thrust" :-)

We should be getting twice max rpm torque when stalled , so 44 ft lbs at 30,000 rpm , 44 X 30,000 div 5252 = 251 HP

With a 30,000 rpm on the pinion theres a 6,880 rpm output potential , a 1:1 chain ratio would give a 225 MPH speed , this is way unrealistic , so probably a 1.5 :1 ratio would be better , theres a 21 tooth on the gearbox so a ~30-32 tooth axle would be good , that'd increase stalled "thrust" to ~1,250 lbs ..................LOL, I won't be driving it .

I haven't the faintest idea what the stalled torque will be , we'll see what the test produces :-)

Cheers
John

[turboron]

John, in the beginning when men were men and engineers were engineers they solved their problems with this "hands on" method. Good luck with the test.

Thanks, Ron

[azwood]

Wow those are some impressive numbers I'd drive it for sure but I'm far from you.guess I'll have to wait for my Kart to to run

[azwood]

Sept 13, 2019 6:44:30 GMT -5 turboron said:

John, in the beginning when men were men and engineers were engineers they solved their problems with this "hands on" method. Good luck with the test.

Thanks, Ron

Necessity is the mother if invention

[Johansson]

A very interesting test!

I don´t think that 225mph is unrealistic, with a low drag vehicle and a long enough track I´d say you would be running well above 200mph. My old JU-01 did 306km/h and still accelerating over the one mile finish line and it had perhaps a bit more than half the power of this engine.

[racket]

Hi Ron

Yep , I like "simple" , its easy to calibrate and doesn't suffer from "gremlins" in the electrics ;-)

Cheers
John

[racket]

Hi Anders

Yeh , in the right vehicle it'd certainly have the potential for >200 mph , something like a junior dragster chassis maybe , and a couple of miles of old airstrip .

Good to see you back in your workshop , all fresh and rearing to get back into the bike after a summer break .

Cheers
John

[Johansson]

I wonder how an engine like this would perform in a thai longboat?



Thanks John, I have missed the late winter nights in the workshop. Not as fun to be there when it is hot and nice outside, I don´t understand how you guys can do what you do in the Australian furnace heat.

Cheers!
/Anders

[racket]

Hi Anders

I think it'd be pretty good , only a fraction of the weight of an IC engine .

Yep , hoping to get the 12/118 development finished before it gets much hotter , its gunna be 31 C tomorrow , time to start thinking about sitting under a shady tree fishing rather than sweating it out in my shed.

I can sit back in the aircon and enjoy watching what you snow bound guys get up to over winter :-)

Cheers
John