Team Go Dog, Go! Modified Partial Streamliners

[Seldom Seen Slim]

Yes -- no question (from me, at least) about tire growth at higher speeds.  I was talking about (and so were the others, I think) the reduction in overall height due to the load.  I expect that there's a point/speed where the two cancel out one another, meaning the torque bonus given when the tire is spinning slowly and squished down - goes away as the squish goes away when the spinning makes it grow.

But tire circumference wasn't WW's topic - the Partial Streamliner is -=- so I'll return control of the thread to him.

[wobblywalrus]

The Triumph runs relatively narrow v-rated steel belted Metzeler radials.  Not much growth expected with these and a slow bike.  On a big fast bike like the 1400 cc Kawasaki with wider tires it might be a different story.  All of my old data is based on tire circumference.  One of my winter projects will be to calculate a conversion factor between tractive force calculated using tire circumference and the torque method to tractive force figured out by the horsepower and speed method.

Does anyone have a good tire rolling resistance equations or coefficients of rolling friction for radial motorcycle tires?  My equations from Hoerner and Cooper are based on the older bias ply tires.   

[wobblywalrus]

The Triumph will be raced until Spring 2015.  That year I will race in Australia with the big valve head.  Probably that will be my lifetime fastest speed.  Bonnie and I will both retire in August 2015.

A guy like me needs a retirement project to keep busy and out of trouble.  My sister inherited my father's Toyota truck.  It is a four cylinder with the last version of a carbureted engine.  As much as possible of that truck will be my power train for project "Model B Roadster."  Right now I am trying to talk her into selling me the truck and I will stash the engine, trans, diff, etc. away until 2015 when I start the build.   

[JimL]

PM me with an address....I've got a useful little book that may help with your 22R project.....I'll mail one to you.

Regards, JimL

[wobblywalrus]

Thanks, Jim.  I will PM you with my address.  Today I was going to talk to my wife about this project.  I did not.  Some inner voice tells me I need to think this one through before I commit.  Cars are far more complicated than bikes and there are so many more parts.  I will build a roadster.  I need to figure out what I want vs what I can afford, etc. 

[wobblywalrus]

Project "Model B Roadster" is moving along.  There is a 1990 Toyota Tacoma sitting out in the driveway.  It has a 22RE engine and I take good care of it.  It is my wife's truck.  Lately we are discussing a new vehicle for her.  This old truck will be part of the roadster.  The decision was easy.  The government is a little out of control here.  This project is five to seven years down the road.  Who knows how hard it will be to register and license a special construction vehicle?  It will be easier if I have the vehicle and I am simply modifying it.

The big job was talking to Rose.  This donor vehicle is her truck and it will be another project.  We have been married 32 years and she knows my weakness for collecting and hoarding rusty junk I never use.  I showed her the roadsters in The Rodders Journal, the hot rod kits, and the pictures of the new body parts being made in Ohio.  I told her I would use new stuff as much as possible.  She gave the OK.  Now I will spend five years collecting all the info I can about mating a Toyota Truck with a Ford Model B.

The magazine The Rodders Journal deserves a lot of credit.  It is a classy publication that presents hot rodding in a format I can show and discuss with my wife and daughters.       

[wobblywalrus]

These next posts are about aero.  "The Racing Motorcycle" by John Bradley will be the primary reference.  He has a lot of information on partial streamlining in Volume 1.  A reference to "Bradley" will be to this book.  These posts will illustrate, without a doubt, that I am not a rocket scientist.  Hey, we all cannot be Miss America.  Someone has to be at the lower end of the bell curve.

The 2007 configuration is shown in the photo.  Aero changes are the fairing, the low seat, and the little tail section behind the seat.  The speed I obtained with the horsepower available is plotted on the graph by the circle with the dot in the middle.  This is part of Bradley's graph on page 67.  Properly designed racing bikes are near the lower line and road bikes with lousy aero are near the upper line.

My bike had horrible aero in 2007.  I would have gone faster naked.  The cross-sectional area at the fairing trailing edge is the base area.  It is very large.  I could fit almost entirely within this base area with only my hands and helmet top projecting.  To quote Bradley "Shapes like this, which many people think of as low drag, are not.  They suffer from high base drag because the pressure is still very low when the flow separates at the large base area."  In other words, where the air passes the trailing fairing edge there is a large low pressure zone at the edge of, and behind, the fairing.  Air is sucked into a large turbulent wake behind the fairing.  This creates base drag.

There were some naked Triumphs similar to mine at the 2007 meet.  We discussed the horsepower and speeds of our bikes.  It was obvious to me that something was very wrong.  I had a lot of work to do.  The next post will discuss the 2008 changes and show that year's dot.

 

[debgeo]

WOW that book is pricey!!! Looks like good info .Will watch with interest. I have been using info provided to me by Bob Bakker. Like you some of the info challenges my IQ.   ps From listening to some of the beauty pageant contestant's talk I think they may be at bottom of bell curve.

Disclaimer I not saying they all fit this description as my daughters best friend went to college on a full scholarship. She almost won in her state.

[Dr Goggles]

   ps From listening to some of the beauty pageant contestant's talk I think they may be at bottom of bell curve.

What?...that's outrageous!

http://www.youtube.com/watch?v=lj3iNxZ8Dww

[4-barrel Mike]

Dr. G:  That should be in the Blonde joke thread!   

Mike

[55chevr]

Dunno why it was posted here but that is funny ... you can't make this subaru up.

[debgeo]

Dunno why it was posted here but that is funny ... you can't make this subaru up.

  Read post 308 & 309 and you will understand. Just having a little fun with WW

[wobblywalrus]

Deb, Bradley's main expertise is with smaller displacement road race bikes.  He emphasizes proper setup, the shape of the engine power curve, gearing, aero, etc.  Racing success with those little buggers depends on mastering these things.  Right now I am limited to what I can achieve with a 70 to 80 horsepower engine in a big heavy bike.  Like Bradley, horsepower is limited and I need to work with setup, engine power curve, gearing, aero etc. to get speed.  Fortunately, the LSR partial streamliner is similar to a road race bike from an aero viewpoint and Bradley's advice applies.  My guess is, if you are in a similar situation, the book's cost is worth it.

It is 2008.  This is my first experience with salt termites.  What awful creatures they are!  My bike is being eaten alive.  The fairing lower is changed so it covers the engine crankcases and a belly pan is installed.  This will keep the salt out of the undercarriage and it will help aero.  It is visible in the picture.  A 6-inch shorter rear fender is installed to reduce drag at the back end.  This is hidden in the photo.

The front fender is a harder decision.  There were, and are, many record holding Triumphs with naked front wheels.  The disadvantage of a naked wheel is the rotating atmosphere that surrounds it.  The rotating air around the top of the wheel is traveling in the opposite direction of the prevailing airflow.  This creates turbulence and drag.  Also, the naked wheel sprays salt all over everything.  I made a front fender and shaped it to help aero.  The flared sides direct the air around the boxy lower fairing.  Other changes are a non-o-ring chain and removing the front brake.  This will slightly reduce rolling friction drag.

The horsepower vs speed graph is shown with the 2008 runs.  They are the two dots in the 115 to 120 mph range.  My other two 2007 runs are plotted, too.  They are in the 90 to 100 mph area.  Speed is greater and this is mainly due to some engine work.  Note how the resistance to motion is dropping.  The aero and other little changes are helping.  I have a long way to go, but I am going in the right direction.   

[wobblywalrus]

The 2007 bike photo is courtesy of Michael Cole.  He was a volunteer working in the timing tower at BUB.  He has set records on a Suzuki rotary.  This 2009 bike photo is taken by Corey Levenson.  This was one of his first attempts at professional photography.

Now it is 2009.  The engine is the same build as in 2008 and it is getting tired.  A set of Nology coils and wires perks it up.  Now it performs the same as it did a year earlier.  A radial front tire is installed and this lowers rolling resistance.  This is the first year I run lower 36# front and 38# rear tire pressures.  Before I used the maximum that was printed on the sidewall.  This probably cancels out and advantages of the radial.  Any differences between 2009 and 2008 will be from aero.

The fairing corners below the headlight, and the corners at the bottom of the lower section, are boxy.  They are smoothed out using larger radius corners.  A tail section is fabricated.  It meets AMA modified partial streamliner standards.  These are the aero changes.

The 2009 dots are shown on the graph.  Note how I am going faster with the same horsepower.  This is due to better aero.  Also, I am getting closer to the lower line.  The resistance to motion is getting closer to a race bike's.

[wobblywalrus]

2010, it is.  The engine year.  Aero work is taking the flare out of the lower fairing trailing edges.  This is done to keep the flow attached as far along the motorcycle sides as possible.  The photo by Ray the Rat shows this.  Also, the crash bars are removed.  I figure out how to tie the motorcycle down on the trailer without using them.  These are small aero changes.

The graph shows that these small changes do not help much.  The 2010 dots are not any closer to the lower line than the 2009 dots.  The 2010 dots are farther to the right and higher than those in 2009.  This shows that more horsepower, rather than aerodynamics, is making me go faster.

Rear sprockets need to be cut for this bike.  I cannot buy ready-made sprockets in the size that I need.  The next posts will show how I use this graph to determine the sprocket size.