(Note: Donations are not tax deductible)

This is a public forum. The opinions expressed here don't
necessarily reflect the feelings of The Folks That Run The Site (that's us)
unless we explicitly say so, ok?


Forum's been "upgraded".
Things will look a bit different.
A *few* posts might have gotten lost in the crossover.
PM bobc with problems, or post in "Website Suggestions".

Author Topic: APS/Ω Gas turbine bike build  (Read 595113 times)

0 Members and 2 Guests are viewing this topic.

Offline wobblywalrus

  • Hero Member
  • *****
  • Posts: 4940
  • Age: 65
  • Location: backwoods Oregon
Re: APS/Ω Gas turbine bike build
« Reply #1110 on: October 19, 2015, 08:58:46 PM »
Aerodynamic symmetry is not as important if flow is detached and turbulent around the tail.  It becomes a bigger issue if the streamlining is developed to the degree that flow is attached to the tail.  Flow will attach to one side and be prevented from attaching to the other 'cause of the exhaust plume.  The pressure differential between attached flow on one side and detached on the other plus the sideways thrust of the exhaust might become an issue.  Splitting the flow so it goes out both sides might help. 

It takes a lot of time and thinking to figure out solutions.  It might be similar to the problem I had with the frame flexing due to the added wind loads and weight of the fairing.  Finally, after years mentally and physically wrestling with the problem, the solution was to add some strength to the fairing and its anchor points so it gives the chassis the needed rigidity.  Some fixes are not obvious.  it just takes time to figure them out.

Offline Mobacken Racing

  • Sr. Member
  • ****
  • Posts: 848
  • Age: 37
  • Location: Östersund - Sweden
  • Turbine junkie
    • Mobacken Racing
Re: APS/Ω Gas turbine bike build
« Reply #1111 on: October 21, 2015, 05:16:23 AM »
At which speeds will side winds and assymetrical fairings start to become a problem with full fairing bikes? 300++km/h or can it happen at such low speeds as 200km/h if the conditions are severe enough?

The bike ran straight as a train at 275km/h but it might very well develop an instability once I get it past 300, no way of knowing before I have tried it I guess.

Offline gidge348

  • Jr. Member
  • **
  • Posts: 41
Re: APS/Ω Gas turbine bike build
« Reply #1112 on: October 21, 2015, 07:18:47 AM »
At which speeds will side winds and assymetrical fairings start to become a problem with full fairing bikes? 300++km/h or can it happen at such low speeds as 200km/h if the conditions are severe enough?

The bike ran straight as a train at 275km/h but it might very well develop an instability once I get it past 300, no way of knowing before I have tried it I guess.

Hi Anders, I don't think there is any easy way to tell what speed you may get a problem without a lot of calculations, but you will know if it happens. One manifestation would be setting up Karman Vortices.
https://en.wikipedia.org/wiki/K%C3%A1rm%C3%A1n_vortex_street
You probably would have felt these when you travel close behind a semi truck on the freeway.

Cheers
Ian...
 
« Last Edit: October 21, 2015, 07:24:23 AM by gidge348 »

Offline Mobacken Racing

  • Sr. Member
  • ****
  • Posts: 848
  • Age: 37
  • Location: Östersund - Sweden
  • Turbine junkie
    • Mobacken Racing
Re: APS/Ω Gas turbine bike build
« Reply #1113 on: October 23, 2015, 10:54:29 PM »
Hi Ian,

Then I´ll stop worrying about the aerodynamics for now and focus on getting the water injection built and tested before next summer, I have made a few changes to the fairings and driving position so I am looking forward to run the bike and find out how fast it will go on the mile.

Cheers!
/Anders

Offline Mobacken Racing

  • Sr. Member
  • ****
  • Posts: 848
  • Age: 37
  • Location: Östersund - Sweden
  • Turbine junkie
    • Mobacken Racing
Re: APS/Ω Gas turbine bike build
« Reply #1114 on: October 24, 2015, 12:58:54 PM »
I ran the bike this afternoon to test the bearing modification, the rotor spins up much easier now and the engine runs smoother somehow. Earlier it had a grumph to it like it was struggling to keep the revs up but now it just whistles along at 700°C exhaust temp which is 100°C colder than before.

I still haven´t checked the thermocouple for faulty temp readings so it might run even colder than that, I could feel a significant drop in rear wheel torque at idle when I applied the rear brake which isn´t very strange since the exhaust temps were much higher before.

https://youtu.be/YcqlQdS-u_M

Cheers!
/Anders

Offline Mobacken Racing

  • Sr. Member
  • ****
  • Posts: 848
  • Age: 37
  • Location: Östersund - Sweden
  • Turbine junkie
    • Mobacken Racing
Re: APS/Ω Gas turbine bike build
« Reply #1115 on: October 26, 2015, 05:20:59 PM »
To help the air enter the engine I added a pair of radiuses to the air box entry tonight.



Hopefully they will reduce some of the supposed turbulence when the air passes the sharp corners and into the air box.



I also made a radiant heat shield for the thermocouple, you can see that slots are cut in the pipe so the exhaust can pass over the thermocouple for faster response.



I´ve also figured out a way to lock the rear brake so I won´t have to start the bike with the rear wheel in the air, a small washer can be fitted behind the brake grip to lock it in place. I´ve just made cad drawings of it and will 3D print it tomorrow in nylon.



Cheers!
/Anders

Offline bbarn

  • Sr. Member
  • ****
  • Posts: 618
  • Age: 49
  • Location: Harmony, PA
Re: APS/Ω Gas turbine bike build
« Reply #1116 on: October 27, 2015, 07:56:45 AM »
Just because I have seen these before Anders:

Not sure the price on this one is the best, was just showing a sample of what you can get off the shelf or if you were so inclined to make one of your own from this idea.

http://shop.terratrike.com/Locking-Brake-Lever-Set-p/tt600178.htm

The elegance of this one is the simplicity of the design. It's one of those "Why didn't I think of that" type of solutions...someone is getting good money for a simple device...
http://kiwavmotors.com/en/hand-tools/magazi-motorcycle-brake-lever-lock-detail
I almost never wake up cranky, I usually just let her sleep in.

Offline Queeziryder

  • Full Member
  • ***
  • Posts: 140
  • Age: 52
  • Location: Royston UK
  • Former funnybike racer now Salt crew
    • G&N Racing
Re: APS/Ω Gas turbine bike build
« Reply #1117 on: October 27, 2015, 01:42:39 PM »
Hi Anders
Whatever you use to lock the rear brake, attach a large streamer/remove before flight tag so you don't forget to remove it
DAMHIK  :-D  :-o

Neil
Old enough to know better, but too interested in speed to care

Offline Mobacken Racing

  • Sr. Member
  • ****
  • Posts: 848
  • Age: 37
  • Location: Östersund - Sweden
  • Turbine junkie
    • Mobacken Racing
Re: APS/Ω Gas turbine bike build
« Reply #1118 on: October 27, 2015, 04:42:24 PM »
bbarn: Thanks for the hint, that is a clever way of locking the brake. My version turned out even smaller in size so think I´ll go for that design.

I printed the rear brake lock wedge today.



It seems to stay in place as well, good thing so I won´t have to buy a snowmobile brake caliper which has an extra lever for locking the brake in place.



As you suggested Neil I have the wedge fitted to the safety cord so I cannot lose it or forget to remove it, that is good since I tend to forget everything once the bike is running. :)



Cheers!
/Anders

Offline Glen

  • Global Moderator
  • Hero Member
  • ***
  • Posts: 7007
  • Age: 84
  • Location: South West Utah
  • SCTA/BNI timer 1983 to 2004, Retired,. Crew on Tur
Re: APS/Ω Gas turbine bike build
« Reply #1119 on: October 27, 2015, 06:02:00 PM »
Anders on the new intake be sure to cut the sharp corners off at the top and bottom of the new addition. :cheers:
« Last Edit: October 27, 2015, 07:18:35 PM by Glen »
Glen
Crew on Turbinator II

South West, Utah

Offline Old Scrambler

  • Sr. Member
  • ****
  • Posts: 689
  • Age: 72
  • Location: Wherever I park the RV
  • Going Fast - Slowly
Re: APS/Ω Gas turbine bike build
« Reply #1120 on: October 27, 2015, 07:14:53 PM »
Anders.............regarding the air-intake...........speed causes a lot of crazy things to happen to the air behind a fairing. I have no idea how much air you need. At some unknown speed you may have somewhat of a vacuum :-o  What is the possibility of extending the air-intake to the inlet in your fairing?  Take a look at the intake-ducts on an F-15 or newer USAF fighter-plane.  Also..............do you need clean air?  What would happen to your turbo-vanes if some SALT was ingested?   
2011 AMA Record - 250cc M-PG TRIUMPH Tiger Cub - 82.5 mph
2013 AMA Record - 250cc MPS-PG TRIUMPH Tiger Cub - 88.7 mph
2018 AMA Record - 750cc M-CG HONDA CB750 sohc - 136.6 mph
2018 AMA Record - 750cc MPS-CG HONDA CB750 sohc - 143.005 mph
2018 AMA Record - 750cc M-CF HONDA CB750 sohc - 139.85 mph
2018 AMA Record - 750cc MPS-CF HONDA CB750 sohc - 144.2025 mph

Chassis Builder / Tuner: Dave Murre

Offline Mobacken Racing

  • Sr. Member
  • ****
  • Posts: 848
  • Age: 37
  • Location: Östersund - Sweden
  • Turbine junkie
    • Mobacken Racing
Re: APS/Ω Gas turbine bike build
« Reply #1121 on: November 01, 2015, 01:57:17 PM »
Anders on the new intake be sure to cut the sharp corners off at the top and bottom of the new addition. :cheers:

I just went out and filed them down a bit to avoid the risk of cutting up my arms while working on the bike, it felt wrong somehow since my father used to tell me never to cut corners... :-)

Anders.............regarding the air-intake...........speed causes a lot of crazy things to happen to the air behind a fairing. I have no idea how much air you need. At some unknown speed you may have somewhat of a vacuum :-o  What is the possibility of extending the air-intake to the inlet in your fairing?  Take a look at the intake-ducts on an F-15 or newer USAF fighter-plane.  Also..............do you need clean air?  What would happen to your turbo-vanes if some SALT was ingested?  

The engine needs roughly one cubik meter of air per second, and as you say it is impossible to estimate by the looks of the bike how the air is passing through the fairing and into the engine.

I really need clean air, any salt or sand particles will wear the compressor wings down in no time at all. If it wasn´t for that I could have made a simple ram air scope that takes in air from the sides behind the front wheel, much easier and much better air flow.

I heard a rumor about the Y2K gas turbine bike trying for the land speed record but it didn´t even make it out of the pits before the engine intake screen was clogged with salt.

There is another difficulty involved as well, the intake duct needs to work in both low and high speeds. At stationary/low speed the engine must be able to suck air through it without restrictions, so a long and tapered ram air intake that works perfect at high speeds would choke the engine.
« Last Edit: November 01, 2015, 03:10:56 PM by Mobacken Racing »

Offline Old Scrambler

  • Sr. Member
  • ****
  • Posts: 689
  • Age: 72
  • Location: Wherever I park the RV
  • Going Fast - Slowly
Re: APS/Ω Gas turbine bike build
« Reply #1122 on: November 02, 2015, 12:21:40 PM »
I am trying to design a Ram-Air intake system for my NA bike with carbs..................I don't know if your turbine needs ram-air......or a duct through which it SUCKS air.....but I know it needs CLEAN air and possibly QUIET air.  Your speed alone could move INTO the air at better than a cubic meter per second. Could you build a box (horseshoe around the frame just aft of the steering stem) with a sizable intake duct (split around the the stem) to the relatively clean air above your front fender?  The bottom ends of the box would feed the turbine. You may be able to install some type of high-flow filter in the box. I don't know if that type of intake should be sealed or if some amount of open-air could be available for slow-speeds without filter restriction. This would allow you to close-off more of the DIRTY air from the front wheel.

The top of the box would be directly below the chin of your helmet..............and quite wide to hold more air..............think about the 'dead' space between your forearms........or maybe I'm dreaming and should take a professional class :-D   
2011 AMA Record - 250cc M-PG TRIUMPH Tiger Cub - 82.5 mph
2013 AMA Record - 250cc MPS-PG TRIUMPH Tiger Cub - 88.7 mph
2018 AMA Record - 750cc M-CG HONDA CB750 sohc - 136.6 mph
2018 AMA Record - 750cc MPS-CG HONDA CB750 sohc - 143.005 mph
2018 AMA Record - 750cc M-CF HONDA CB750 sohc - 139.85 mph
2018 AMA Record - 750cc MPS-CF HONDA CB750 sohc - 144.2025 mph

Chassis Builder / Tuner: Dave Murre

Offline Mobacken Racing

  • Sr. Member
  • ****
  • Posts: 848
  • Age: 37
  • Location: Östersund - Sweden
  • Turbine junkie
    • Mobacken Racing
Re: APS/Ω Gas turbine bike build
« Reply #1123 on: November 04, 2015, 04:44:02 PM »
I am not sure if having the air intake sticking out the sides is a good idea, it will add lots of drag and in case I tip the bike with the engine running it will ingest lots of dirt.

A quick peek at what I am cooking up at the moment, I have started to design a new 300hp gas turbine for the bike which should be ready to install in the frame in a year or two. I might have written something about it earlier but here is the story so far.

I have 3D printed out a split pattern for the compressor backplate that I need to get the build going, on the old engine I spent roughly 100 hours manually milling it from a solid chunk of aluminum so if this work it will save me lots of time.





I printed a 3D scanned version of the compressor wheel for comparation.



Here is the rear part of the pattern fitted with dowels.



Last night I made a pair of suitable sized flasks and tonight I made the sand pattern.



I sifted the sand closest to the pattern to get a smooth surface finish for the casting.



I used copper tubing to form the downpour and the vents, the downpour fits to the thickest part of the pattern that solidifies last.



Baby powder is brushed on the surface so the sand won´t stick together when I ram the sand in the second flask.



Looking really good! A couple of minor cracks on the diffusor wedges but that can easily be fixed on the cast part. Time to pull the second pattern from the sand.



I am very pleased with how easy the 3D printed PLA patterns release the sand, I haven´t even bothered to smooth out the raw printed surface with sand paper.



The plan is to cast the part on Friday, keep your fingers crossed! :)

Cheers!
/Anders

Offline manta22

  • Hero Member
  • *****
  • Posts: 3386
  • Age: 80
  • Location: Tucson, AZ
  • What, me worry?
Re: APS/Ω Gas turbine bike build
« Reply #1124 on: November 05, 2015, 09:48:04 AM »
Very impressive work, Anders!

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ