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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 532018 times)
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fredvance
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« Reply #315 on: November 17, 2010, 10:33:58 AM »

I would be looking at trying to get as much air around/past your arms and shoulders. IMHO

  Fred
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WORLDS FASTEST PRODUCTION MOTORCYCLE 213.470
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WOS 2011 235+MPH
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Sponsers Catalyst Composites, Johnny Cheese Perf, Knecum Racing Engines, Murray Headers, Carpenter Racing
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« Reply #316 on: November 17, 2010, 11:23:09 PM »

Thanks for the advice.  The body work is being redone.  The back half this year and the front half the next year.

The speed vs power chart is one of my best tuning tools.  It will be used to figure out the rear sprocket size I will need next year.  It is also used to figure all sorts of other useful stuff, like how much power I will need to reach a certain speed.

This winter's aero work will add 5 mph, as my best guess.  This speed increase will not require any more power.  It is drawn as a horizontal dashed line on the chart.  Hopefully the intake tuning and jetting this winter will produce 75 horsepower on the dyno in Beaverton.  This will be 65.4 horsepower on the salt.  A horizontal line is drawn across the graph at this horsepower.  Another dashed line is drawn, parallel to Bradley's lower curve, upward from the right end of the dashed line.  This represents the speed increase due to more power.  This dashed line intersects the horsepower line.  This intersection point is estimated to be as fast as I will go, 136 mph.  The sprocket size will be calculated in the next post.


* Speed Estimate.jpg (148.17 KB, 629x480 - viewed 203 times.)
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wobblywalrus
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« Reply #317 on: November 19, 2010, 10:11:38 PM »

More figuring...

The sprocket I will have made must be large enough to assure that the chain does not rub on the hub.  About 3/16 of an inch clearance between the bottom of the sprocket teeth and the hub is enough.  This will provide room for the chain.

The first step is to lay a sprocket on a piece of paper and to trace its shape, including the teeth and the mounting holes.  Also, I draw in the parts of the hub that are closest to the sprocket teeth.  The "C" shaped lines on the drawing show the sprocket mounting flanges.  The number of teeth on the traced sprocket is not an issue, although the sprocket must fit on the hub.  This is a 42-tooth Sunstar sprocket from Triumph.  Next, I fugure out the exact center of the sprocket.

Next, I measure the traced sprocket radius to the bottom of the teeth.  Also, I figure out the sprocket radius with 3/16 inch clearance between the teeth bottoms and the hub.  This is the smallest radius the new sprocket can have.  Some simple multiplication and division tells me the minimum number of teeth on a rear wheel sprocket.  It is usually a fractional number.  I round it to the highest whole number.  The smallest sprocket I can use on this hub has 36 teeth.

A roadster question.  I can get an older 22R Toyota engine with a carb or a newer 22R four cylinder engine in a lot better condition with fuel injection.  The injectors are screwed into the intake manifold just upstream from where the manifold bolts onto the head.  It will be difficult to fit this massive, ugly as Medusa, system under a Model B hood.  Is there a simple way to toss the system and to mount a carb setup?

In this part of Oregon we do not have the periodic smog system checks like they do in California.  We mail in our registration fee every two years and no one in the govt knows what we do to the car.


* Sprocket Worksheet.jpg (114.4 KB, 627x480 - viewed 194 times.)
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wobblywalrus
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« Reply #318 on: November 21, 2010, 01:36:43 AM »

All of these graphs and formulae are used to make everyday decisions.  The first one I do is to calculate the sprocket size I need to go 136 mph.  A 40 tooth one will be OK.  I order one.  Then, I think about ordering a 36 tooth one, too.  Over 90 horsepower will be needed for me to go the 150 mph that sprocket will allow.  There are no plans to build the engine to make that power.  I will order a 38 tooth sprocket.  That will work good with the big valve head and I should get into the lower 140's.

This is the last post on this subject.  These are the most complex calculations I do.  I am not a mental kinda guy.


* Even More Sprocket Calcs.jpg (116.61 KB, 480x625 - viewed 199 times.)
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« Reply #319 on: November 23, 2010, 09:15:53 PM »

The streamlining will be redone during the next two years.  The rear section will be redone this year.  The front fender will be remade, too, if I have time.   This is a tall bike with a short wheelbase and I am a big guy that does not fold into a tight tuck very well.  Miracles will not happen.  I will be happy to drop down to Bradley's lower line on the horsepower vs speed graph.

It is important to plan the streamlining.  The front and rear sections must compliment each other, fit the bike, and cover the rider.  The first step is to draw up the bike dimensions.  The pegs and handlebar grips are shown.  This tells me where my hands and feet will be.  Two lines mark my shoulder width and two more mark the width of my bum.  A line perpendicular to the bike center line shows the back of the seat.  All is drawn to scale.

About the roadster.  The Model B Ford is a rare car, I thought.  I was wrong.  They are popular for making hot rods and there are all sorts of parts and a lot of Model A items will fit.  This is great.  It seems that the car will need to be inspected at the department of motor vehicles.  I will keep the fuel injection on the 22R engine until I get the thing registered.  A forum member sent me a nice book and a lot of hints on how to make the injection system work in a Model B.  Thanks, JimL.  This summer I will start to build the roadster shed.


* Bike and Rider Dimensions.jpg (131.55 KB, 777x600 - viewed 209 times.)
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« Reply #320 on: November 24, 2010, 10:53:12 PM »

Usually I write up these graphs and charts during my work lunch time.  The figuring for this streamlining shape got me so engrossed that I worked on it for most of the afternoon.

The sketch shows the plan view of the widest part of the streamlined shape.  The 25-inch width gives coverage for my hands, legs, chest, and arms.  My shoulders are marked with lines behind the hand grips.  The shape appears to be wider than my shoulders.  It is not.  My shoulders are higher than the widest part of the shape and they are at the edge of the shape at that height.

The width is figured, now it is time to calculate the length.  The rules say "Any aerodynamic aid on any section behind the rider and his seat shall only exceed the rear edge of the tyre up to a distance equal to half of the rear wheel rim diameter."   An easy to understand rule!  This is 17 / 2 = 8.5 inches.  I will use 7.5 inches to be safe.  The front of the streamlining will be above the front axle.  This gives me an 83 inch total length.

Ideally, the widest part of the shape is at 25 percent of the untruncated shape length.  This is too far back on this bike.  I want the widest part to be in front of my widest part, my hands and shoulders.  The widest part at 25 percent of the truncated length fits better.  The widest part is 62.25 inches in front of the back end.

It is important that the air flow near the streamlined skin stay attached to the shape.  I do not want the rear section included angle to be more than 10 degrees in order to keep the flow attached.  Trial and error is used to figure out the best rear shape.  The one shown has a 10 degree included angle and no more.

The back end is truncated to a 9 inch wide flat section with this shape.  This is not ideal.  This increases drag 15 to 20 percent according to Bradley's data.  It is the best I can do with this short wheelbase bike.  There are some things I will do to address this problem.


* Streamling Plan View.jpg (134.33 KB, 795x600 - viewed 216 times.)
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WhizzbangK.C.
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« Reply #321 on: November 25, 2010, 03:15:29 AM »

The rules say "Any aerodynamic aid on any section behind the rider and his seat shall only exceed the rear edge of the tyre up to a distance equal to half of the rear wheel rim diameter."

Are you not running Bub's next year? That doesn't look like anything in their rule book. Just asking is all.

Have you considered extending the swing arm to allow you a longer rear fairing to minimize the truncated area?
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« Reply #322 on: November 25, 2010, 09:52:20 PM »

This is a 2010 FIM rule.  Yes, I will be at BUB.

The wheelbase is extended now, but not by much.  Somewhere between 1.5 to 3 inches, as I recall.  The bike seems to be well balanced now.  It has a good drift in the corners.  A bit more drift in the rear than the front and the handling is slow and steady but tolerable.  I am afraid that with a longer wheel base there will be too much weight on the front tire and it will drift more than the rear.  That would be really spooky.  I do not want to permanently extend the swing arm for this reason.

I thought more about your idea.  A fellow on this forum knows about some swing arm extensions made by Harris in England.  That concept might be the answer.  I could extend the arm for racing on the salt and shorten it back for the street.  Then I could get rid of the truncated end.

This Christmas I am buying a welding set for Werner.  Maybe some bolt on extensions can be a future project.  The young guy needs something useful to do. 
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« Reply #323 on: November 26, 2010, 12:24:22 PM »

The BUB bike #240, a Triumph, is one of the best partially streamlined bikes based on my miniscule knowledge of aero.  This is Tom Mellor's bike.  It is a very good example of how a longer wheelbase can be used to give more length.  Tom's approach to streamlining is best.  Mine is compromised.  My bike is like a street rod and it must be a daily driver, too.

The Triumph is measured up in side view as shown on the sketch.  Gretchen took some measurements with me on it.  It is very important to include the rider in the overall design.  Look at Scooter Grubb's website, 2010 BUB meet, Day 3, Page 2.  A big fellow or lass is on Tom's #240.  Note the fit.  Another picture is in the 2009 BUB meet photos, Day 2, Page 1.  Tom is on Tom's #240.  See the perfect fit.  This makes a big difference in aero.


* Streamlining Side View.jpg (167.51 KB, 782x600 - viewed 276 times.)
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« Reply #324 on: November 26, 2010, 03:34:42 PM »

You're going through a lot of the same process that we've used to determine the aero shapes on our bikes. What we've found to work well is to make full size templates of side profiles and frontal areas with the rider in riding position on the bike. We used large cardboard boxes, like a water heater or refrigerator carton, flattened out and propped up beside the bike. Have an accomplice (it's always good to have accomplices, or even minions, that way you have someone else to pass the blame onto if it doesn't work out exactly right), trace your outline on the bike in full riding apparel and position, and the bike outline onto it in plan view.Top, side, and frontal views. That way you can draw out the shapes that you think may work on the cardboard to really visualize them fully. I don't know about you but my mind works best in full scale and 3 dimensions.

 That's the process that we used to develop the shape on the 7419 bike. It seemed to work well for us anyway. Here's a picture of it right before we loaded up to leave this year.





Of course, as everyone knows this body is wood. We were running out of time and I wanted to at least prove the concept for the bike, this year with the chassis and engine mostly done I'll be starting early in the spring to make a real body for it, more in line with the original concept of some sexy fiberglass, like so.



I kind of went to extremes to minimize frontal area and maximize the tail length, and was concerned that the large slab sides would make it uncontrollable in cross-winds, but it turned out to be a complete non issue and rode very well through some side gusts over 10mph, so I feel comfortable putting the effort into a more complex streamlining setup.

And yes, Tom Mellor's bike is a very nice piece of kit. I told him personally that his body work was a great inspiration to me in the design of the rear end of mine. I don't know if he took that as a compliment though, LOL.
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« Reply #325 on: November 28, 2010, 09:31:05 PM »

Ed, did the streamlinined rear section work as intended?  It sure looks like it would.  I am using your idea of drawing things.  It helps.

The English road racer, Peter Williams, has written about his career.  He helped to develop the John Player Norton road race bikes in the 1970's.  They did a lot of wind tunnel testing and they experimented with lowering the windshield.  One time they lowered it enough to greatly improve aero.  Peter says he could feel the air rushing across his back when the screen height was correct.

The windshield on the Triumph was lowered 3 inches this fall.  This will let me tuck down lower toward the tank.  Hopefully the air will flow over me rather than around me.  Also, my lower stance will reduce the large gap between the back of the windshield and the front of me.  My upright position and the air gap are seen on photos of the bike, on Scooter's 2010 BUB website, 2010 BUB Photos, Day 3, Pages 8 and 9.

It took two tries.  It is important to have a rounded front.  The first time I did it I did not get the shape right.  The second time it came out OK. 

     


* First Time.JPG (102.65 KB, 640x427 - viewed 195 times.)

* Second Time.JPG (119.77 KB, 640x427 - viewed 195 times.)
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WhizzbangK.C.
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« Reply #326 on: November 28, 2010, 10:35:49 PM »

"Ed, did the streamlined rear section work as intended?  It sure looks like it would." 

I believe that it did help. If you look at the frame I ran the last 2 years and the bike this year, my overall height is about the same, width is slightly narrower now because I don't have to hang my legs outside the frame and mechanical parts. I made no changes to the engine that would have an affect on power. I've never been able to get acceleration in 4th gear with the old configuration, in fact it would always slow down. This year it was gaining speed in 4th gear for a bit, with a sprocket combo that I tried last year without success. I was feeling really good on that run until the engine locked up again, right in the middle of the trap, LOL. I now have a collection of toasted pistons all pointing to the fact that I need more clearance between the cylinder wall and the piston. That will be remedied next year for sure.
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« Reply #327 on: November 29, 2010, 01:18:54 AM »

My first and last attempt at web journalism.  http:www.motorcycleclassics.com/restoration-technical/sidewalk-motorcycle-tire-repair.aspx
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« Reply #328 on: November 29, 2010, 09:24:18 AM »

 cheers cheers cheers cheers cheers cheers cheers
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George---Sidecar in progress
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« Reply #329 on: November 30, 2010, 10:14:08 PM »

Thanks, Deb.  That article was fun to make.  It was done in 2008.  Heidi Rose was in a photography class and this was a good way to show her the practical uses of photography.  She was interested in professional picture taking.  The whole experience taught her to concentrate her efforts on finding another way to make a living.  Photography is a nice hobby or a way to supplement your income from a steady day job.

The side view shows me tucked down behind the windshield that was lowered three inches this winter.  This is the higher position and I stick up into the air.  I am too high.  The lower position shows me tucked down behind a windshield that is lowered another 3 inches.  This tuck will be just about right.  I will lower the windshield when I rebuild the front fairing.

The old tail section is shown by dashed lines and the new by solid.  The new wide truncated end creates excess drag and this is reduced, somewhat, by reducing the truncated end height.  This excercise shows the value of using photographs as a design tool.     

 


* Rear Section Side View.jpg (74.93 KB, 629x480 - viewed 238 times.)
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