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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 1017886 times)

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Offline THRUXTONERICH

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1335 on: September 07, 2013, 04:11:39 AM »
Freud made a recent post in which he lamented the attempts at replacing the camshaft with more modern ideas.  He had a link to a Swedish company.  I have been trying to find that post with no luck.  Any clues to where it is?

This one??? http://www.agap.se/home.htm

Offline JimL

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1336 on: September 07, 2013, 11:24:29 AM »
About 20 years ago I saw a small twin set up to run solenoid controlled valves (no cams).  In addition to the reliability problems  with the solenoids, there was trouble finding a way to ramp open and closed to "chase the piston" or "be chased" in the case of exhaust valves.  The solenoids werent working in the overlap region if they were fast and strong enough.  That takes out scavenging, for sure.

The builder and I brainstormed a while about "over amp/frequency drive" techniques.  That is the cause of a type of automobile speaker damage where we'd find the ceramic magnets had hyper-extended and held at a flutter point.  The clue was erroded areas on the cone magnets and corner chipping.  The kids would put big amps against stock speakers and that condition was the result found in warranty examinations.

The right frequency, at the right amps, and you can partial, near full, or over extend and then hold at a chosen position....but with damage accumulating.

We thought that method might be a way to induce variable rates of "hold positions" for computer control of finite valve/time lift/close rates.  How to actually write that kind of code, and make it work, was mind numbing to think about!  Plus....all those broken engines in the development phase while a fellow learns how much he really dont know! :-P

I suppose somebody has figured it out, by now.  I gave up contemplating the whole deal a long time ago.  There is only so much brain damage you can stand, after all. :-D

Regards, JimL

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1337 on: September 07, 2013, 11:39:03 PM »
There are two forms of drag we usually look at, rolling resistance and aero drag.  Rolling resistance drag is pretty much the same regardless of altitude.  Aero drag, in the simplified way we usually look at it, has the air density as a component in the numerator to the first power.  In other words, aero drag is proportional to are density.  There is less aero drag at B'ville than Lake Gairdner most of the time 'cause the Utah salt flats are at a higher altitude with thinner air.

Thinner air has less oxygen and it produces less compression in naturally aspirated engines.  NA engines produce less power at higher altitude places like B'ville than at lower venues such as Gairdner.  Some folks claim the power loss at higher altitudes is evenly compensated by the ease of pushing the thinner air.

The consequence of all of this is that the horsepower needed to overcome rolling resistance is a greater proportion of the total available power at higher altitudes for NA engines.  NA engines have an advantage at lower altitudes.

What I am getting from calcs is the opposite of what folks are saying, Jon.

This picture shows the front of the bike when it was being weighed.  The best way to get good photos for fronat area measuring is to take them from far away and then to crop and enlarge them on the computer.

The distance between the center of the roundels on the fairing sides is 25.5 inches.  This is 4.8 inches when the picture is measured with a scale.  25.5 / 4.8 = 5.31 to 1.  This is the reduction ratio for the photo.  The area inside the black lines is the frontal area and it is 7.64 square feet.  The maximum width is 28 inches.  I am about as low as I can get in the photo and still see straight ahead.
 

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1338 on: September 08, 2013, 12:17:17 AM »
Thanks for all of the info, Jim.  My bike is wider than yours.

My first exposure to the von Karman street was racing a bike having a big wide handlebar mounted windshield.  The windshield, I figured, was more aerodynamic than me, and using it would reduce the aero drag.  The harmonic frequency of the vortex shedding was nearly the same as the natural frequency of the bike rotating around the steering head at high speed.  A big speed wobble resulted. 

My old college textbook has a picture of a von Karman street, an equation and a few paragraphs, and that is all.  I did not know much about it when I designed the tail.  I did consider it, though.  The primary purpose of the shallow angle of convergence from front to back, along the sides, is to keep the flow attached to the sides in moderate side winds.  I did not want to have the pressure difference that comes with detached flow on one side and attached on the other.

The open tail end with lots of room for air to flow up under the tail and out the back is an attempt at eliminating the low pressure area that occurs behind a walled off tail.  I am hoping this will reduce turbulence behind the tail and the chance to form a von Karman street.  So far, at speeds up to the 140 mph the bike has gone, it is working.

Offline JimL

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1339 on: September 08, 2013, 08:56:35 AM »
That makes sense.  I'm sure the tail could be better on my bike.  I suspect the drag is jumping up at my historic top speeds (160-165 range).  Its probably because of too short and pinched in the tail.  If I get to continue this game, I will certainly try to work on that idea.

I keep looking at current production car aero around the wheel openings.  The engineers are doing those slight flare and flatten shapes for a reason, and I'd like to understand it.  Of course, I know it is something for the highway speed range...but still curious.

Fun stuff!

JimL

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1340 on: September 09, 2013, 12:27:15 AM »
Yea, Jim, there are some different things happening with cars.  The new Prius roof is slightly higher on the sides over the doors than it is in the middle of the roof.  I know that Toyota pays a lot of attention to aero on those little things.  Is that a styling exercise or does it help?




Offline JimL

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1341 on: September 10, 2013, 12:38:34 AM »
I am guessing it is for the designed cruise speed aero, and so would be wrong for very high speeds.  Keep in mind that the roof shape must have changed to accept the available built in solar charging system (used for parked vehicle ventilation to reduce air conditioner load at startup in hot weather). 

The rear corners are the biggest point to pay attention to.  That is a hard, sharp break to get the Kamm effect for the body side wrap around.  In the world of metal stamping, that type of draw is a mighty tough job to keep correct.  The clamp force in the dies must occur just right to accept the sharp crease.  If you get it wrong, it pulls ridge lines lengthwise through a very visible area of the panel. 

You see this especially around the front and rear door handle reliefs on many cars.  Slight distortion in nearby panel area is a sure sign that the dies are worn and need rework and replating.  That skilled die work is the last realm of the true artisans of auto manufacturing.  I wonder if it has been turned over to computers? 

Those dies take a lot of maintenance, and their last home is often South America where your following years of crash parts may be stamped.  A friend in the trade once said that all the dies to make a brand new '65 Mustang Fastback are still sitting in some South American warehouse!  I don't know if thats really true, but its cool to consider.

Knowing that much, those sharp rear corners have really got to be worth it, to make the stamping line work so hard!  Also, a good friend was US1 for many years in his boat racing class.  The fastest boats had a very sharp corner at the hull bottom-to-transom line.  The sharper the corner, the less the water drag.  I have every intention of paying attention to that effect as I go forward with my reconfiguration of my big orange whale.

JimL

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1342 on: September 11, 2013, 01:47:10 AM »
The Triumph is supposed to be my street bike.  It spends most of its time being worked on for LSR.  My buddies don't bother to ask me if I want to ride somewhere with them.  The bike is always apart.  Rose wants to go out for a ride.  I can't.  The bike is in pieces.  It is a nice day, which does not happen here all that much.  I want to go out for a blast around the hills.  No way.  The bike is being worked on.  It got to be too much so I went up to the Triumph shop today and bought another scoot.

One thing I wanted to do was put on my old racing pipes.  They actually are a street legal Arrow setup that Triumph sells.  Legal with the baffles in them, anyway.  Triumph has a map for them according to the dealer.  They loaded it for free.  They plugged the bike into a laptop and the bike and the computer talked to each other for half an hour.  They said it was done and showed me all sorts of colorful graphs and tables with throttle openings, rpm's, and mixtures.  Then they asked me a few questions.  I made some chimp grunts and squeals to tell them how I totally comprehend all of this new stuff.

Offline generatorshovel

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1343 on: September 11, 2013, 05:56:37 AM »
MMMMMM ?
I see a twin engined Triumph streamliner coming up soon ? :?
Tiny
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I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline Old Scrambler

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1344 on: September 11, 2013, 08:27:27 PM »
Before the streamliner..........there will be a garage addition :lol:

I ride an Aprilia Pegasso almost daily.........but occasionally take my '73 Honda CB750 or my '67 Triumph T100C for a run just to keep them happy.  Welcome to the world of the multi-bike garage and a well used battery tender.
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 tauruck

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1345 on: September 11, 2013, 11:32:25 PM »
Nice one Bo. I hope you have miles of fun on the new one. :-D

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1346 on: September 12, 2013, 12:25:42 AM »
Thanks, Rich and Jim, about info on the valve actuation method.  It is interesting and I will post what I find out. 

Mike, Tiny, and Dennis, race bikes are like wives.  One is more than the average guy can take care of.  These Triumphs are pretty plain vanilla when they are standard.  The gas mileage is real good, however.  Other than the pipes, and a swap to a 790 intake cam, I will leave it alone.

The drag horsepower formula in Bradley's "The Racing Motorcycle" is rearranged to give me the drag coefficient.  First, I calculate the rpm I was running through the mile, I get the horsepower at that rpm from the dyno chart, and I read the speed through the mile from my timing slip.  Second, I subtract the rolling resistance power loss from the total power to get the aero power loss.  Then I figure out the aero drag coefficient.  Years of dinking around with the fairing and tail has reduced the coefficient by half.

The fellow who did my valves, guides, springs, and seat work at Kibblewhite offered to flow test the head.  This info I can pass along to Triumph Performance to get a new set of cams or to have some ground.  This data will be a big help.

Offline JimL

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1347 on: September 12, 2013, 10:39:51 PM »
Neat formula, Bo.  It shows my cd must be about .41.  There's no way my little 650 has more than about 75hp, so that makes me think my aero problem will be more difficult than I thought. :|

Thanks for that,
JimL

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1348 on: September 13, 2013, 12:24:37 AM »
Cascade Moto Classics gave me a Triumph shipping crate.  It was used to move a Trophy triple from the midlands to Oregon.  The Bonnie just fits with the tail removed and set forward and up on the bike.  Custom fitting the bike to the crate, and the crate to the bike, will be a winter job.   

Offline Peter Jack

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1349 on: September 13, 2013, 12:33:33 AM »
Nice score Bo. That'll make things a lot easier when you go to ship it "Down Under".  :-D :-D :-D

Pete