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Author Topic: APS/Ω Gas turbine bike build  (Read 393794 times)
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wobblywalrus
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« Reply #225 on: August 17, 2013, 11:16:41 PM »

That weld is in a place where it will get a lot of stress.  The method I use is a bit different.  Circumferential welds bother me a lot so I avoid them on the outer sleeve, too.  The outer sleeve is a saddle that covers 1/2 to 3/4 of the tube.  A fracture in the circumferential weld needs to travel around the edge of the saddle before the tube breaks.  This is something I almost always see in time to make a repair.  I am tired now and will send a picture tomorrow.     
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Grandpa Jones
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« Reply #226 on: August 18, 2013, 12:03:20 AM »

Hi Anders,

In the USA, the FAA publishes a manual called:

AC 43.13, Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair

http://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/99861

Check Chapter 4, starting at page 67. Some good info there on welded tubing repairs. In fact, that
book is a wealth of info for us garage fabricators. It is kind of a throwback book, covering a lot of
"old-school" aircraft repair, but still a solid resource.

I'm enjoying your build, looking forward to seeing it run.

Cheers, Dave
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manta22
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« Reply #227 on: August 18, 2013, 11:31:59 AM »

That weld is in a place where it will get a lot of stress.  The method I use is a bit different.  Circumferential welds bother me a lot so I avoid them on the outer sleeve, too.  The outer sleeve is a saddle that covers 1/2 to 3/4 of the tube.  A fracture in the circumferential weld needs to travel around the edge of the saddle before the tube breaks.  This is something I almost always see in time to make a repair.  I am tired now and will send a picture tomorrow.     

I agree with your comments about circumferential welds; that's why I recommended angle-cut ends or fish mouth ends on the outer sleeve.

Regards, Neil
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Regards, Neil  Tucson, AZ
wobblywalrus
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« Reply #228 on: August 18, 2013, 12:19:51 PM »

Neil is correct about this. 

Highway bridges and other structures take a real beating and modern trucks carry a lot more weight than the truck loads used in those old designs.  Fatigue cracks at butt welds happen.  Most of the time the metal alongside the bead cracks and the weld does not.  Sometimes on round members we would slide a sleeve over the tube near the fracture, butt weld the fracture as best as we could, slide the sleeve down over the weld, and weld the circumference of the sleeve ends to the old tube.  Eventually the old tube would crack at the edge of a circumferential weld where sleeve was attached.  More about this later.

I-beams and W-beams crack too.  Sometimes at butt welds and often in the middle of the beam where it is heavily loaded and there are no welds.  We can't take the bridge apart to replace the beam in most cases.  We jack the beam up so it is sorta straight and butt weld the crack.  Then we weld fish plates across the butt weld where we can.  The plates add strength.  Also, the fracture path needs to make a bunch of 90 degree bends before the member breaks in half.  This is like Neil's fish mouth.  Fractures do not like to turn corners.

The swingarm in the photo is lengthened 3 inches by adding a section.  There might be a sleeve inside.  I do not remember.  Fish plates are welded on on both sides.  The fracture path is very long when this is done.  Also, a fracture would need to make eight 90 degree bends before the arm broke.  A joint with fish plates will not fracture to begin with is my experience. 


* Fish Plate.JPG (189.53 KB, 800x533 - viewed 186 times.)
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Mobacken Racing
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« Reply #229 on: August 19, 2013, 04:01:33 PM »

Thank you very much guys for the insight in this, I will get back to this during the winter when I strip the frame for the final welding and will make sure you think the sleeves look ok before I paint the frame.

I will read that paper you linked to Dave, and thanks for the praise! smiley

Thanks to some internet access problems I haven´t been able to post this until now, I got this done two days ago.



The suction line from the oil tank to the pump needed to be secured somehow, and I came up with these little buggers.



The oil tank ready to go, only the fuel tank left.



I am not sure if cable ties are the fastener of choice of you ask the safety crew at Speed Week so I will wire lock it later.



For this test I´ve decided to use the wooden seat to save some manifacturing time, I don´t want to rush that build since I really want the seat to be both comfortable and decent looking.



Cheers!
/Anders
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Mobacken Racing
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« Reply #230 on: August 20, 2013, 01:05:23 PM »

I made a trip into town today and bought a bag full of couplings and a hydraulic hose so I could hook the air starter and propane preheat up with quick release couplings, this way it will be very easy to disconnect the bike from the starting gear once the engine is up and running.



Cheers!
/Anders
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« Reply #231 on: August 22, 2013, 11:52:59 AM »

Last night I built the rear brake caliper "rod" or what it is called, the brake torsion restrainer perhaps? Smiley



I don´t dare to ride the bike without a rear brake since I have no idea how high the idle torque will be, not fun if the rear wheel starts eating itself into the gravel road outside my house...



The rod is made out of chromemoly tubing so even if it looks a bit thin it is more than strong enough.



After that I started to fit all the stuff I removed earlier from the frame, this time with locking nuts and bolts that aren´t twice the lenght needed...



The other side.



Today I found an hour while the little girl was sleeping and assembled the gearbox with the set of SKF bearings with C3 play I ordered a week ago, later I will fit cheramic hybrids to cope with the revs but according to my jet mentor and friend John Wallis these ones should be ok as long as I keep the revs below 10.000rpm.



Fitting the bearings.



The bearings and the gland in place, a snug but still loose enough fit against the shaft so it shouldn´t leak much exhaust gasses into the bearings.



6 bolts cut to lenght and drilled for locking thread, they will be used to bolt the freepower housing and shaft tunnel together.



Bolts torqued down and lock wiring almost done!



No advanced lock wiring, just to make sure the bolts won´t come completely lose.



With that done I could fit the turbine wheel and thread lock the bolt, I wouldn´t want to drop the turbine wheel at 33.000rpm...



Cheers!
/Anders
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manta22
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« Reply #232 on: August 22, 2013, 11:59:15 AM »

Anders;

A beautiful job!

In the second photo the open end of a round frame tube is visible. It would be better to weld a cap on to close the end of the tubing wherever possible. It not only keeps the salt out but it increases the stiffness and strength of the tube where other tubes intersect closely.

Regards, Neil  Tucson, AZ
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Regards, Neil  Tucson, AZ
Mobacken Racing
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« Reply #233 on: August 22, 2013, 12:27:33 PM »

Anders;

A beautiful job!

In the second photo the open end of a round frame tube is visible. It would be better to weld a cap on to close the end of the tubing wherever possible. It not only keeps the salt out but it increases the stiffness and strength of the tube where other tubes intersect closely.

Regards, Neil  Tucson, AZ

I have planned to do that later when I have the frame back in the jig to finish welding it up, but thanks anyway for pointing it out. There is lots I don´t know about frame construction (sleeving butt welds for example) so keep the hints coming! smiley
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Mobacken Racing
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« Reply #234 on: August 23, 2013, 01:05:34 PM »

The weather was fine today so I decided to take the bike outside to take some pics, but first I had to fit the gearbox. To do that I had to mill away some material from the rear gearbox mount to make room for the brake caliper mount that was a bit in the way.



Plenty of room! Smiley



It wasn´t very easy to get the bike outdoors, I had to use all of the scrap wood laying around to get enough clearance for the tanks so they wouldn´t hit the doorway.



Here is a bunch of pics, no need to comment them so I´ll keep quiet. Smiley















Cheers!
/Anders
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manta22
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« Reply #235 on: August 23, 2013, 01:10:12 PM »

Anders, I can hardly wait to see you run this jewel!

Regards, Neil   Tucson, AZ
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Regards, Neil  Tucson, AZ
Mobacken Racing
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« Reply #236 on: August 23, 2013, 04:13:03 PM »

Thank you Neil, I am very close now to the first test run. Mostly some wiring and brake hoses left to do and then a check of the fuel and oil control.
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« Reply #237 on: August 26, 2013, 03:12:30 PM »

I've said it before, and I'll say it again... This thing is amazing!! Anders, you are doing a great job!  cheers

Looks fast just sitting there!
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Maybe there is no Heaven. Or maybe this is all pure gibberish. The product of a demented hill billy who has found a way to live out where the winds blow. To sleep late, have fun, drink whiskey, and drive fast on empty streets with nothing in mind except falling in love or getting arrested.    H.S. Thompson
Mobacken Racing
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« Reply #238 on: August 26, 2013, 03:57:51 PM »

I've said it before, and I'll say it again... This thing is amazing!! Anders, you are doing a great job!  cheers

Looks fast just sitting there!

Thank you very much!

I start to feel a little nervous about the first run, I really have no idea what to expect since this is the first time I run a turboshaft engine. Pure jet engines I am used to but with this one the energy release is put to good use instead of just making noice. smiley

Cheers!
/Anders
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« Reply #239 on: August 27, 2013, 04:02:03 PM »

Some days are just better than others, today I could write off two of the larger things on my to-do-list without any effort at all!  cool



I took the bike into town to a company that could make steel braided brake hoses, a couple of hours later I returned home with a bag of hoses and no idea what they would charge me for it.  smiley



Later tonight a blog reader dropped by with a set of five industrial sprockets ranging from 18-22 teeths, not only did he order the blanks for me but he drilled, reamed and made the key slot in all five for me! Needless to say we have the greatest blog followers on planet earth!



A perfect fit. All I need to do is to make some shims to get the right alignment with the rear sprocket and make a steel "hat" that fits on the drive shaft and locks the sprocket in place.



Cheers!
/Anders
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