Author Topic: APS/Ω Gas turbine bike build  (Read 931034 times)

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Offline wobblywalrus

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Re: APS/Ω Gas turbine bike build
« Reply #75 on: April 11, 2013, 01:21:14 AM »
An airplane mechanic friend told me that jet engines are simpler than piston driven ones.  Now I see why.

Offline Mobacken Racing

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Re: APS/Ω Gas turbine bike build
« Reply #76 on: April 11, 2013, 03:27:53 AM »
AH-Ha now I get it. It can't run away if it ain't got no fuel :cheers:

Exactly, as simple as that on a gas turbine. On a piston engine you would melt the pistons if you leaned the AFR out but a turbine simply loses revs if it gets less fuel.

An airplane mechanic friend told me that jet engines are simpler than piston driven ones.  Now I see why.

Many people don´t understand this and think building a model gas turbine is waaaay more difficult than say a model v-twin glowplug engine, nothing could be further from the truth. Tolerances are sloppier and there is only one moving part in the engine. Didn´t say that they are easy to build though, just not as difficult as most seem to believe.

Offline gidge348

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Re: APS/Ω Gas turbine bike build
« Reply #77 on: April 11, 2013, 09:39:22 PM »
An airplane mechanic friend told me that jet engines are simpler than piston driven ones.  Now I see why.
Yep,
   That’s right, think of a turbocharged piston engine, turbo compressor, inlet valves, pistons, cams, crank, suck, squish, bang and push, exhaust valves, exhaust turbine.

   Now throw away everything between the turbo compressor and exhaust turbine and just put in a burner can...... hey presto.... jet engine.

   The only down side is takes longer than a piston engine to reach full revs and uses mucho fuel. Not really a problem in aircraft or land speed racing.

Offline Frank06

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Re: APS/Ω Gas turbine bike build
« Reply #78 on: April 13, 2013, 10:22:32 PM »
What are you using for oil pumps?
E-Racer

Offline Mobacken Racing

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Re: APS/Ω Gas turbine bike build
« Reply #79 on: April 14, 2013, 03:13:15 PM »
I use a Marco UP12 gear pump for oil pressure and two universal gear pumps (used for pumping diesel etc) capable of 15L/min to suck the oil out of the engine.

The reason I use two scavenge pumps is because the oil gets mixed with air in the engine and froths badly so I need an overcapacity to avoid filling the shaft tunnel with oil, another benefit is that if one pump stops for some reason the other one should keep the oil from flooding the bearings until the run is over. There is no practical way of monitoring if the pumps are working or not so two pumps gives a measure of security.

I´ve spent four hours this weekend on the throttle regulator, now I need to buy some fittings and stop bolts before I can do anything more.



I made a lid for the needle valve and grided the o-ring spacer so the rings got a perfect fit around the needle valve shaft when the lid was in place.



The hole for the pressure relief valve got M12 threads so a bolt can be used to adjust the spring pressure, this way I can adjust the max fuel pressure.



Risking ten of my fingers I freehanded a throttle lever on the circular table saw, the last touch was done with a flap disc on the angle grinder.



After some fine tuning I got a throttle wire play of 22mm between idle and full throttle, should be enough since I shouldn´t need any finer control of the revs.

Cheers!
/Anders

Offline salt27

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Re: APS/Ω Gas turbine bike build
« Reply #80 on: April 14, 2013, 05:07:54 PM »
Anders,
Just is case you were not aware and you do make it to Bonneville the SCTA rules state "control levers shall have at least a 1/2 in. diameter round ball end". (7.B.4)

Very impressive machine work.

 Don

Offline 38flattie

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Re: APS/Ω Gas turbine bike build
« Reply #81 on: April 14, 2013, 05:43:34 PM »
Amazing!

Keep up the great work, Anders!
With sufficient thrust, pigs fly just fine. However, this is not necessarily a good idea. It is hard to be sure where they are going to land, and it could be dangerous sitting under them as they fly overhead. -- RFC 1925

You can't make a race horse out of a pig. But if you work hard enough at it you can make a mighty fast pig. - Bob Akin

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Offline Mobacken Racing

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Re: APS/Ω Gas turbine bike build
« Reply #82 on: April 15, 2013, 02:44:13 AM »
Anders,
Just is case you were not aware and you do make it to Bonneville the SCTA rules state "control levers shall have at least a 1/2 in. diameter round ball end". (7.B.4)

Very impressive machine work.

 Don

Thanks! :-)

No worry about the 1/2" ball ends, this is no hand lever but a throttle wire lever, the end of the arm will be drilled for the throttle wire and I will use a regular twist throttle on the handlebars.

Cheers!
/Anders

Offline Mobacken Racing

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Re: APS/Ω Gas turbine bike build
« Reply #83 on: April 15, 2013, 02:44:40 AM »
Amazing!

Keep up the great work, Anders!

Will do! :-)

Offline Mobacken Racing

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Re: APS/Ω Gas turbine bike build
« Reply #84 on: April 16, 2013, 05:23:40 PM »
Today I finished most of the throttle regulator except for the wire mount and some drilled holes for fitting the regulator to the air box, that will have to wait until I get the throttle grip I ordered a couple of days ago.



The holes for the fuel ports were drilled and threaded with R1/4" and the holes in the end were threaded to be blanked off.



With the holes blanked off and JIC 7/16" couplings fitted (same as AN4) the regulator looks like this. I will probably do something about the finish later when I know that it works like it should, until then it is a waste of time to do any polishing.



The next project for the evening was to continue building the air intake for the engine, I rolled an aluminum plate into the right shape and fixed it to the frame.



Then I split an aluminum tube to get a radius for the front wall of the air intake, this should make the ram air enter the air box a little bit better. :-)



With those parts tacked together I could make a template of the side walls.



I only had enough aluminum for one side at home so I will have to go get the rest of my stash later.



This is what it will look like anyway, the engine looks smaller and smaller as the air intake grows but it is needed if the engine is to get particle free air. The Y2K bike at Bonneville hadn´t room for more than a crude screen and it hardly made it out of the pits despite its 400hp Allison 250 C18 engine.



One last thing I did before I called it a night was to sketch a bit more on the ram air intake on the fairing, I can sacrifice some intake area to get the looks right since the space between the fender and fairing lets lots of air through so the engine should get more than enough air anyway.



Cheers!
/Anders

Offline Mobacken Racing

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Re: APS/Ω Gas turbine bike build
« Reply #85 on: April 18, 2013, 07:52:48 AM »
Got the throttle grip today, a very compact one so even with the front brake in place it doesen´t stick far outside the fairings.



As Salt27 stated there is a rule that the levers must have a 1/2" ball at the end, but is there any rule how long/short the grip can be? Can I shorten the original brake grips so they don´t stick outside the fairings and weld an aluminum ball at the end or do they need to have a certain minimum length?

Cheers!
/Anders

Offline Stainless1

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Re: APS/Ω Gas turbine bike build
« Reply #86 on: April 18, 2013, 03:09:58 PM »
10 inches between your thumbs I think... other than that they can be as short as your hands can fit. 
Stainless
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Offline Mobacken Racing

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Re: APS/Ω Gas turbine bike build
« Reply #87 on: April 18, 2013, 05:14:21 PM »
Thanks for that, no problems with the thumbs since I use standard forks so it´s all good then! :-)

Offline Mobacken Racing

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Re: APS/Ω Gas turbine bike build
« Reply #88 on: April 21, 2013, 02:10:30 AM »
I had a beer, rum and workshop evening last night, it was badly needed for a modern man at home with the youngest kid all week long. :-)



Two holes for M6 insex bolts were drilled in the throttle regulator and a throttle wire mount was made and welded to the regulator, now it is ready to be fitted to the bike for good.

Cheers!
/Anders

Offline tauruck

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Re: APS/Ω Gas turbine bike build
« Reply #89 on: April 21, 2013, 02:47:52 AM »
My best friend Guido is a Dane and he also loves Rum after work. What is it with you guys? :cheers: Nice work man.