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Author Topic: APS/Ω Gas turbine bike build  (Read 393160 times)
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Seldom Seen Slim
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« Reply #390 on: March 27, 2014, 08:08:54 AM »

Speaking of runs in ever increasing speeds, I'm positive that SCTA/BNI inspectors will REQUIRE you to do just that because not only of the newness of the bike -- but because of the non-traditional engine.  They'll want you to run, no problem there, but they also want proof that it'll be a safe run for you. grin
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Jon E. Wennerberg
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« Reply #391 on: March 27, 2014, 08:48:13 AM »

a shrug and a "oh well", in my experience, usually costs a lot more financially the second time. moreso, if your wife is raising your baby by herself.


Just what are you getting at here? I can spend countless hours twisting soldered together copper wires without having a clue if that result has anything to do with my frame integrity, are you suggesting that if it folds in some particular way I should deem my bike frame unsafe and build a new one?

I┤ve had this thread going for quite a while now and people have given me plenty of good advice which I have heeded (more or less), and experienced builders have had all the time in the world to tell me that I am on the wrong track with the frame build. Never heard anything so far.

If you are a tech inspector telling me straight out that this frame will never pass inspection for this and that reason, why then I would thank you, bow to your wisdom and follow your every lead. If a complete stranger insinuates that my frame will make my children fatherless without any explanation whatsoever I get rather pissed off for obvious reasons.

/Anders
I apologize. That did come out the wrong way.

Merely stating that any time i have left something at a shrug and a "oh well" it didnt come out as expected( i dont trust bikes, all my stuff has 4 wheels) I love the build and would love to see it run fast and hard. I was merely meaning, if you can do anything to avoid the shrug and "oh well", please do it. I have a baby girl too, and shudder at the thought of me not seeing her grow up. So i did sell my projects and am working on something cooler and slower.
I do know that speed is the ultimate test of a build, and i guess i misinterpreted the shrug and oh well as choosing to leave something to chance. Something that could be very important.

I have several lengths of 3/8" stainless tubing (or use brake line tubing) Something like that could better replicate a scale frame and maybe give you results you can see easier than with hard wire, and even be tig welded together.

Keep up the hard work! I am currently a keyboard racer and live vicariously through projects like this.
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Mobacken Racing
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« Reply #392 on: March 27, 2014, 01:54:09 PM »

Hi Jon,

You are probably right about that, I would only appreciate a couple of slow runs to get the feel of the salt track before going for a record. The engine will be tested and modified until it can be reliably do full throttle runs all day long as long as it has enough time to cool down between runs.

I will probably plan to stay for both BUB and Speed Week when I take the bike to the US so there should be plenty of opportunities to run it. smiley

I apologize. That did come out the wrong way.

Merely stating that any time i have left something at a shrug and a "oh well" it didnt come out as expected( i dont trust bikes, all my stuff has 4 wheels) I love the build and would love to see it run fast and hard. I was merely meaning, if you can do anything to avoid the shrug and "oh well", please do it. I have a baby girl too, and shudder at the thought of me not seeing her grow up. So i did sell my projects and am working on something cooler and slower.
I do know that speed is the ultimate test of a build, and i guess i misinterpreted the shrug and oh well as choosing to leave something to chance. Something that could be very important.

I have several lengths of 3/8" stainless tubing (or use brake line tubing) Something like that could better replicate a scale frame and maybe give you results you can see easier than with hard wire, and even be tig welded together.

Keep up the hard work! I am currently a keyboard racer and live vicariously through projects like this.


Hi Crackerman,

I sort of guessed that I misread your post, that is the biggest downside of internet communication. I can see now that my "shrug and oh well" statement sounds like I don┤t give a Dodge but that is far from the truth, trying to break a land speed record is only fun if you live to brag about it in the pub afterwards.  smiley

Thanks for the encouraging words!

Cheers!
/Anders
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Mobacken Racing
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« Reply #393 on: March 30, 2014, 02:49:58 PM »

I┤ve been welding the frame from time to time during the weekend so now it is only a couple of welds left, the rear fairing mounts and seat mounts are left to do but they don┤t affect the frame stability.



I┤ve also finished the winter mods on the daily driver, my Triumph Bonneville -67 that I┤ve modified a tad. smiley



I weighed the frame to see how heavy it has become, 16.5kg with the triple tree still in place in the steering head. Not bad. The scale is a bit funny since it begins at 80kg, that is why it looks like it weighs almost 100kg...



Cheers!
/Anders
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wobblywalrus
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« Reply #394 on: March 30, 2014, 11:14:43 PM »

Weight is not as big of a factor for land speed racing as it is for the other forms of bike competition.  That is not really heavy for a frame of its length.
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Mobacken Racing
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« Reply #395 on: March 31, 2014, 05:17:31 AM »

I know, it is just that I really would like to get a 1:1 power to weight factor or better. Looking good so far as long as I can get the calculated power out the engine. smiley
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Mobacken Racing
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« Reply #396 on: April 01, 2014, 03:35:58 PM »



Got some photos taken today so I can see how I need to make the rear fairings, I┤ll make a fairing plug out of styrofoam next.



Cheers!
/Anders
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saltwheels262
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« Reply #397 on: April 01, 2014, 03:58:35 PM »

 you may not like decelerating with all your weight so far forward.

any way to stretch out on the frame with your feet by the rear axle ?

Bf262
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bub '07 - 140.293 a/pg   120" crate street mill  
bub '10 - 158.100  sweetooth gear
lta  7/11 -163.389  7/17/11; 3 run avg.-162.450
ohio -    - 185.076 w/#684      
lta 8/14  - 169.xxx. w/sw2           
'16 -- 0 runs ; 0 events -- made a 2 state change in ZIP codes

" it's not as easy as it looks. "
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« Reply #398 on: April 01, 2014, 10:09:46 PM »

Those forks look a lot better than the original ones you had.  The forks can be shortened by using a shorter top spring and putting a second spring on the damper rod so they do not extend all of the way out.  An advantage of this method is it increases the overlap between the top and bottom tubes and as a consequence, the fork rigidity.

 
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Mobacken Racing
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« Reply #399 on: April 02, 2014, 11:02:16 AM »

you may not like decelerating with all your weight so far forward.

any way to stretch out on the frame with your feet by the rear axle ?

Bf262

Unfortunately not, the jet exhaust is right behind where my feet are placed.
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Mobacken Racing
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« Reply #400 on: April 02, 2014, 11:04:25 AM »

Those forks look a lot better than the original ones you had.  The forks can be shortened by using a shorter top spring and putting a second spring on the damper rod so they do not extend all of the way out.  An advantage of this method is it increases the overlap between the top and bottom tubes and as a consequence, the fork rigidity.

I found this walkthrough on how to shorten a Hayabusa fork, fit a sleeve under the piston and cut the spring spacer almost as much.

http://www.suzukihayabusa.org/forum/index.php?topic=135724.0
« Last Edit: April 02, 2014, 02:18:53 PM by Mobacken Racing » Logged
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« Reply #401 on: April 02, 2014, 03:24:22 PM »

Very simple and effective method , you can tailor it with preload from either direction esp to reduce lift under load or speed
I have restricted my travel to 50mm , 35 left in compression and 15 for lift,
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Mobacken Racing
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« Reply #402 on: April 04, 2014, 03:43:54 PM »

The GSXR SRAD fork is a bit different from the hayabusa fork, found that out last night when I took it apart. I have to cut the inner tube and rethread it apparently.

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JimL
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« Reply #403 on: April 05, 2014, 07:09:16 PM »

Weight forward is good, and we are learning to put that weight a little higher, closer to the steering stem (must be the opposite at the rear of the bike).  I am moving my forward ballast higher, to try to reduce a very small "weave".  There is some good info out there that indicates 'too low' center of gravity forward reduces the inverted-pendulum effect that dampens weave at higher speeds.

The riders weight is not a good cantilever for this effect, because we are not very solid through our shoulders.  Back when I was racing sailboards, I learned the hard way that using your arms and shoulders to power the rig was much slower than "hooking in" to a harness that put the load through your lower back or hips.  Once I learned to "hook in" I quit losing so many races.  That effect is why my fixed ballast and components weights will be moved higher in the forward area of my bike.

Food for thought...I run very similar front forks but a different approach.  I use external stops on the lower legs.  They are set where there is contact (stopped) at rest, with me on the bike.  By the time my speed is above 100 or so, there is a little travel available (due to aero drag lifting the nose of the bike) and my forks are soft enough to absorb the ruts, holes, and the "river crossing" without kicking the front end.

I have tried running a front end with reduced length from shortening the extension (with the spring more preloaded).  I didnt like the feel of it....a lot of chatter in the front end.

With my current setup, when I roll off throttle at 150-160 the front end doesnt settle back onto the stops until about my turnout point.  It is very easy to feel when the bike settles back down.  The aero lift at top speed does not go away when you close the throttle....only when you get slower ( even when the throttle is off.)

I suspect you will have no engine braking.  I prevent engine braking by staying in top gear until very low rpm, before shifting down for a turnout.  It feels more stable to let aero drag do all of the high speed deceleration, and save the engine braking for later.  My son and I have both found this a comfortable way to run the bike.

We all love following your project and really appreciate the time you put into sharing it with us.

Thank you,
JimL
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Mobacken Racing
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« Reply #404 on: April 06, 2014, 05:58:58 AM »

Weight forward is good, and we are learning to put that weight a little higher, closer to the steering stem (must be the opposite at the rear of the bike).  I am moving my forward ballast higher, to try to reduce a very small "weave".  There is some good info out there that indicates 'too low' center of gravity forward reduces the inverted-pendulum effect that dampens weave at higher speeds.

The riders weight is not a good cantilever for this effect, because we are not very solid through our shoulders.  Back when I was racing sailboards, I learned the hard way that using your arms and shoulders to power the rig was much slower than "hooking in" to a harness that put the load through your lower back or hips.  Once I learned to "hook in" I quit losing so many races.  That effect is why my fixed ballast and components weights will be moved higher in the forward area of my bike.

Food for thought...I run very similar front forks but a different approach.  I use external stops on the lower legs.  They are set where there is contact (stopped) at rest, with me on the bike.  By the time my speed is above 100 or so, there is a little travel available (due to aero drag lifting the nose of the bike) and my forks are soft enough to absorb the ruts, holes, and the "river crossing" without kicking the front end.

I have tried running a front end with reduced length from shortening the extension (with the spring more preloaded).  I didnt like the feel of it....a lot of chatter in the front end.

With my current setup, when I roll off throttle at 150-160 the front end doesnt settle back onto the stops until about my turnout point.  It is very easy to feel when the bike settles back down.  The aero lift at top speed does not go away when you close the throttle....only when you get slower ( even when the throttle is off.)

I suspect you will have no engine braking.  I prevent engine braking by staying in top gear until very low rpm, before shifting down for a turnout.  It feels more stable to let aero drag do all of the high speed deceleration, and save the engine braking for later.  My son and I have both found this a comfortable way to run the bike.

We all love following your project and really appreciate the time you put into sharing it with us.

Thank you,
JimL

Hi JimL,

I┤ve been thinking about adding mounts for lead weights but decided that it is easy to make aluminum tube clamps if I find that I need to add weight somewhere on the bike.

I am not sure I follow you about your fork modification, are you strapping them down like the dragracers do?

I don┤t know how much engine brake I will have, I suspect that at higher speeds it will be similar to the top gear in a normal motorcycle.

Thank you for your support! I am constantly humbled by the wealth of knowledge gathered here and can┤t wait to become a fellow land racer instead of just another foreign wannabe with an unbloodied nose. smiley

Cheers!
/Anders
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