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Author Topic: APS/Ω Gas turbine bike build  (Read 404924 times)
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wobblywalrus
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« Reply #60 on: April 03, 2013, 10:21:17 PM »

Every now and then someone will take a photo of a bike running through the timed mile when the light angle is just right and the salt halo is seen.  It is a very fine dispersion of salt around the vehicle and rider.  Pretty much everything down low and to the rear is in it.  The only places where it is not are the front upper quarter of the bike.  This would be the rider's helmet, upper shoulders, windshield, and the upper front of the fairing.   
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Mobacken Racing
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« Reply #61 on: April 03, 2013, 10:36:43 PM »

I don't have any fairing experience, yet.
I have researched it from from Diff'rent fairing manufacturers.
and this has to do with stock fairings also.
      the fairing needs to be level with the bike and the ground.
      not pointed up - lift
      not pointed down - it will compress the front forks

when you get up to speed the bike should level out.

that weight@ the rear is good for traction. it's better to keep the weight as low as possible.
I wouldn't put much weight on a motorcycle front end.

I´ll note this, thanks for the info!

Your front fairing looks to me like it will give downforce, there is no large frontal area for radiator and it does not curve around the wheel
 but rather diverts the air to the sides , and your underside will be turbulant so its not like your making a wing

another option for fairing strength is  few more layers of fibreglass inside the body will increase rigidity and reduce the need for extra bracing

Then I am on the right track at least, good to hear. The fairings will eventually be used as a plug to make a new and considerably stronger fairing later when I have given it the shape I want, so no reason to strenghten it in any fancier way than aluminum struts and rivets at this point. smiley
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Mobacken Racing
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« Reply #62 on: April 03, 2013, 11:02:38 PM »

Every now and then someone will take a photo of a bike running through the timed mile when the light angle is just right and the salt halo is seen.  It is a very fine dispersion of salt around the vehicle and rider.  Pretty much everything down low and to the rear is in it.  The only places where it is not are the front upper quarter of the bike.  This would be the rider's helmet, upper shoulders, windshield, and the upper front of the fairing.   

That is exactly what I wanted to hear, thank you! smiley
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Mobacken Racing
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« Reply #63 on: April 05, 2013, 04:22:25 PM »

With the kids asleep and the feancee out on a party I had the evening for myself, and the result was that I headed out to the workshop. Smiley



I got a package with a bunch of nice small aluminum weld lids for the fuel and oil tanks today, I can´t remember how I ever got anything done before I discovered Ebay...



A couple of hours more on the brackets for the fairings, now they stay in place enough so I can strenghten the sides and make brackets there as well.



I have decided to skip the PWM controller and use my old trusty needle valve I made for my turbine pocketbike years ago, a very simple design that regulates the fuel pressure by choking the internal fuel return flow.



This is exactly in line with my goal to have the bike as field repairable as possible, if it starts to leak or jam I only have to fit new needle seals and then it is as new again. No bloody PWM controller that burns out in the middle of nowhere, been there done that with the jet sled we´ve been racing at the Swedish Ice landspeed event...Angry



After testing different needle profiles I found one that produced a decent flow curve.



I even made a test rig for it, hard facts tends to beat guessing sometimes. Smiley



Right now is it under a thick layer of dust in my friends barn, I will go get it this weekend and clean it up some.

Cheers!
/Anders
« Last Edit: April 05, 2013, 04:27:21 PM by Mobacken Racing » Logged
Buickguy3
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« Reply #64 on: April 05, 2013, 09:39:45 PM »

  There is so much satisfaction in doing things yourself. If it works, pat yourself on the back. If it doesn't. Do it over and improve on your design. Doesn't get much better than this.
   Doug  cheers cheers cheers
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I keep going faster and faster and I don't know why. All I have to do is live and die.
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Mobacken Racing
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« Reply #65 on: April 06, 2013, 02:41:09 AM »

Exactly, knowing that you are building something from scratch that might become the fastest on earth some day is very satisfying. If it takes 40 years to get there doesen´t matter since it is the way there that matters. smiley

By the way I will most likely build a new throttle block so I can integrate a max pressure relief valve to it, it will be used as a throttle stop so I can´t rev the engine past what is healthy.

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Buickguy3
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« Reply #66 on: April 06, 2013, 09:30:10 PM »

  Sort of a turbine waste gate.
  Doug  cheers cheers cheers
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I keep going faster and faster and I don't know why. All I have to do is live and die.
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Mobacken Racing
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« Reply #67 on: April 09, 2013, 02:59:18 AM »

 Sort of a turbine waste gate.
  Doug  cheers cheers cheers

Kind of. smiley

I´ve finished the bracket manufacturing for now, the fairings are firmly fixed and will be even more so later when I have made the transition pieces down to the aluminum tanks.



I adjusted the clearance between fender and fairing so it is as tight as possible without them touching while turning or braking hard. An extra high windscreen is ordered from England specially made for these kind of fairings so as soon as it arrives I will see if I can tuck myself in completely behind the fairings.



After that I started building a new throttle valve with an integrated pressure release valve for extra safety against over revs, the old one was a bit bulky and lacked the safety valve so I figured it was best to make one that fits the bike.



I didn´t take much photos but here I am milling out the slot for the throttle arm.



Drilled, tapped and soon countersunk for an M6 insex bolt.



I got this far last night before it was time to go to bed, 30 minutes past midnight. It´s a good thing that I don´t need very much sleep, frees up many extra workshop hours each week! Smiley



Cheers!
/Anders
« Last Edit: April 09, 2013, 03:01:43 AM by Mobacken Racing » Logged
gidge348
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« Reply #68 on: April 09, 2013, 08:52:08 PM »

Top build Anders love what you are doing.
Just a quick question, would it not be better to have the start battery on your support vehicle as once the engine is lit you don’t need all that cranking power anymore?
 Then you only have to carry a small battery to run gauges, data logging etc?
Save a lot of weight in places you may not want it and make packaging a whole lot easier. 
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Mobacken Racing
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« Reply #69 on: April 09, 2013, 11:06:51 PM »

Top build Anders love what you are doing.
Just a quick question, would it not be better to have the start battery on your support vehicle as once the engine is lit you don’t need all that cranking power anymore?
 Then you only have to carry a small battery to run gauges, data logging etc?
Save a lot of weight in places you may not want it and make packaging a whole lot easier. 


The battery is actually the heart of the bike, the gas turbine engine has journal bearings just like a turbocharger that needs 3-5 kg of oil pressure to survive. Since I cannot fit a gravity drain for the oil I use two scavenge pumps that sucks the oil out of the bearing tunnel after it has passed through the bearings. That makes three large oil pumps that runs on 12V.

In addition to that I need a fuel pump capable of 5 bar and some other stuff that runs on battery as well so the bike consumes a lot of energy, I measured the total amperage draw on the pumps with 10°C oil and found that it was in the region of 50A so I need one hefty battery. smiley

As if that wasn´t enough I need some overcapacity to make sure that the battery lasts longer than the fuel, if I lose oil pressure the engine runs dry and destroys itself in seconds... undecided
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Crackerman
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« Reply #70 on: April 10, 2013, 10:08:35 AM »

Would yoube able to run an alternator off of the output shaft of the gear box? It will get you extra run time and voltage will deteriorate much less at the end of the run.
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Mobacken Racing
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« Reply #71 on: April 10, 2013, 11:18:23 AM »

I´ve given the idea some thought during the frame design phase but there is simply not enough room, plus it is one more thing that can cause trouble during a run. sad

The battery would still have to be quite large since it has to be able to cope with a generator failure, I´ve invested way to much work and money in the engine to risk it just to be able to use a smaller battery...
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Seldom Seen Slim
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« Reply #72 on: April 10, 2013, 01:08:23 PM »

A big battery is an asset in most land speed racing where traction is needed to gain speed.  Don't worry about reducing weight unless you've got plenty of good traction.  On ice I'd expect you'll want all the help you can get to hook up.
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Jon E. Wennerberg
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bbarn
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« Reply #73 on: April 10, 2013, 03:30:56 PM »

Look at some of the lithium ion batteries that are available. There are some high amp batteries that are incredibly small and they have a discharge rate that is steady until they are dead. You can get an 18v that weighs a few pounds and is roughly 3 inches thick by 6 inches tall and maybe 8 inches long.

They are pricey especially your first one because the charger is almost as expensive as the battery. Recharge time is way faster than a lead/acid battery too.
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« Reply #74 on: April 10, 2013, 05:53:55 PM »

I totally agree Jon, weight is my friend as long as it is in the right place like it will be here.

I did some research on lithium batteries but the ones I could afford were too cheesy to be trusted. When I found that I could get a higher quality battery for like 1/5th of the price it was an easy choice to pick the lead gel battery instead.

Tonight I continued working on the thottle regulator, I had big plans to draw everything up very professionally in a CAD program instead of the ususal figuring out the design while I build with drawings made on some greasy cardboard piece. It didn´t work out... rolleyes



Testing the fit of the needle valve, a snug fit.



Threading the bolt circle that will hold the needle valve O-ring cover in place.



Here I am about to drill the seat for the fuel pressure safety valve, a spring loaded 10mm steel ball will be set to open slightly above the full throttle fuel pressure to make sure I can´t over fuel the engine.



Not very easy for you to follow all the drilling and milling so I made some kind of explanation how the channels are routed. The fuel enters from the pump and leaves to the injectors from the lower fuel line, and the upper line is the bleed return line to the tank that both the throttle needle valve and the safety valve dumps fuel into.

The needle valve regulates the fuel flow through the bleed line thus regulating the fuel pressure to the engine. Simple and bullet proof. smiley



Cheers!
/Anders
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