Team Go Dog, Go! Modified Partial Streamliners

[manta22]

Thanks for the advice.  I will look for some of that oil when I go up to Portland today.  It was my father's favorite gun oil.

If you are going to Portland maybe it would be a good idea to take the gun along with you. 

[wobblywalrus]

Today I rode all around the northside, the eastside, the west side, and the southside on a big shopping trip.  Most of the immature idiocy is confined to a fourteen square block downtown, according to the locals I talked to.  It still is a safe city to go to if you avoid the city center.

Nitromethane is available by the gallon from the race fuel suppliers.  That is too much of a quantity for this job.  Nitro is mixed with methanol in model airplane race gas.  I got a bottle and used some to clean the oil passages.  It does a good job.

On the way home I stopped at the newsstand and bought the latest "Cycle World."  The Triumph competes in the 1,000cc class.  Hopefully, after 14 or 15 years of working on the thing, I can get 115 hp at 9,500 rpm.  This new Honda, which anyone can buy who has the money, gets a claimed 214 hp at 13,000 rpm.  It is time to take up a new hobby, like golf.     

[manta22]

It's a safe place to go if you avoid the crime area? O..K..

When I was a kid most everyone mixed their own model airplane fuel which we called "bug juice". Methanol, nitromethane, toluene, oil, and whatever else and in whatever ratio anyone thought best. Those Dooling and McCoy engines put out power!

I'll have to get some model airplane gas to mix with Hoppe's Number Nine. Good idea, WW.

[wobblywalrus]

Model airplane fuel was my introduction to the wonders of castor oil.

A 0.0020 bearing clearance is what I want on the rod big ends.  The crank is outside of the manufacturer's specified tolerances as per journal diameter.  The maximum allowed production diameter is 1.6126 inches.  Mine are 1.6130 to 1.6131 inches.  They are too big.  The thinnest shells available, the white coded ones with no polymer coating, were fitted in 2017 with the old connecting rods.  They gave 0.0017 clearance, which is the minimum for racing.

Last year the journals were polished by an expert.  I figured there would be some diameter reduction and there was.  Maybe a couple of tenths.  New rods were fitted.  The clearance is 0.0015 with white uncoated shells.  The new rods have a smaller bore diameter is my best guess.  The old rods had over a decade of racing and several hundred dyno pulls.  This probably enlarged them a few tenths so they put less crush on the shells.

The journals need some diameter reduction.  An e-mail was sent to Winberg crankshafts in Colorado.  Maybe they can help with this.

     

[ggl205]

Honing a couple of tenths out of your new rod big ends shouldn?t reduce crush much but could get you to the minimum racing clearance of .0017?. I worry about taking any more diameter out of the crank journals by polishing. Kind of an uncontrolled machining process.

John

[wobblywalrus]

Good idea.  I will take the rods to the machinist today and get his opinion about honing them.

[wobblywalrus]

Paul, the machinist, looked at the crank and rods.  Plastigage measurements are what I did.  They are not the most accurate method to measure clearances, he said.  He measured the journals with a micrometer.  Then he put the rods in his Sunnen rod honing machine.  Then he zeroed a dial gage between the micrometer jaws with "0" at the journal diameter.  Then he put the dial gage into the honing machine and he measured the clearances.  Clearance was 0.0022 on one rod and 0.0018 on the other.  What I want is 0.0020 on each so a simple rod swap will make it happen.  He told me to adjust my clearances, if I want to, by changing the shells to ones with different thicknesses.

There were uncoated shells in the rods.  Coated shells can be used and the decrease in clearance due to the coating can be ignored, according to Clevite.  The Clevite coating typically reduces the rod big end inner diameter 0.0005 inches according to their literature.  The Polydyn coating is twice that thick and it would reduce the inner diameter 0.0010 inches.   This seems like too much, so a coated shell will be used on the top, only.   This was discussed with Paul and he said it should work OK.

The final setup is a white coded shell with coating on top and a white coded shell with no coating on the bottom.  Clearance is 0.0015 with 0.0005 being considered sacrificial for a "run-in" clearance of 0.0020.

The main journal clearances were measured with plastigage.  The clearance is 0.0015 on all with uncoated white coded shells.  Coated shells will be used on the bottom, only.  This will give 0.0010 clearance with 0.0005 being sacrificial for a 0.0015 "run-in" clearance. 
   

[wobblywalrus]

We started lockdown on the last day in February.  The confinement got to be more than I could handle...so I left town a couple of weeks ago and disappeared with Gypsy into the stix.  This is the first day I have i-net coverage so it is time to see how speedweek went.  The fotos show a typical view through the windshield and Gypsy.   

[wobblywalrus]

Two pix from the trip.  Sheep on Steens Mountain and a nighthawk perched on the windowsill at the field station.

[Stainless1]

Welcome back to the world... unfortunately it's still a mess

[wobblywalrus]

Sometimes it is best to follow the example of the great 20th century philosopher Alfred E. Neumann.

[manta22]

Sometimes it is best to follow the example of the great 20th century philosopher Alfred E. Neumann.

What, me worry?

[wobblywalrus]

This is a link to good info about the situation here.  https://www.opb.org/article/2020/09/14/live-updates-oregon-northwest-wildfires/

[wobblywalrus]

This is the first of three long-winded posts.  It is about the support for steering loads provided by a surface.  The second will be about the vehicle steering dynamics.  The third will be to tie the two together with insight about how it affects the bike's build.

This summer I crossed a big lake in my little boat.  It was a windy day.  The boat was aimed at a point on the shore about a mile upwind from the marina where I wanted to go.  The boat was cocked aside from its direction of travel.  This cannot be done on a land speed bike.  The cycle must be oriented straight down the course.  The side force to keep the bike on the track is provided by the front wheel.  It is slightly cocked so it pulls the front of the bike against the wind so it will stay on the track.  This works if there is sufficient friction between the wheel and the salt surface.

Imagine a 10 pound block resting on a surface.  A 10 pound side load is needed to slide the block.  The frictional coefficient is 1.00  Lets say a five pound load is all it takes.  The friction coefficient is 0.5  This is the static coefficient to friction.  It takes force to keep the block moving across the surface.  This is the dynamic friction coefficient.  It is often less than the static coefficient.

The friction coefficient between steel and ice is large at low pressure loads where the ice is solid under the block.  Higher loads cause the ice to liquify into water.  The friction coefficient between steel and water is low.  This makes ice skating possible.  The skater putting a concentrated load onto the small area under the blades, this liquifies the ice, and the the person is floating across the ice on a film of water.

The above demonstrates why surface friction in dynamic conditions is most important for the racer.  There must be enough friction between the wheel and the surface to provide steering.  The water film under the skater is very thin yet it makes all the difference on whether or not the skates work.  This is the boundary layer and it is the critical factor.

In engineering we look at the loads that cause failure.  Then we compare this to the expected loads.  A factor of safety is figgured.  It is one if the loads to fail the thing are the same as the loads it is designed to withstand.  It is two if the expected loads are half of those that cause failure.

Water in the boundary layer drastically reduces frictional coefficients.  The water must be squeezed out from under the tire in order to provide adequate tire to surface friction.  Major factors are water depth with deep water being the worst.  Velocity is another factor with high speeds the worst.  The water does not have enough time to get squeezed out from under the tire.  Distance is the third.  The water stays under the tire longer if it needs to travel farther to get out from under the tire.  This is why rain grooves are used.  They give escaping water a shorter path to freedom.  Pressure is another factor.  It takes force to squeeze the water out from under the tire.  Dry tire to surface friction is another variable.  Water under the tire, often called hydroplaning, can reduce the contact patch.  Good adhesion within the remaining dry patch is critical.  This is why many racing rain tires have a combination of grooves and softer rubber. 

A spinning wheel drags an atmosphere with it along its surface.  Also, an object traveling through air near, at, or above the speed of sound produces a shock wave ahead of it.  This can affect the surface.  This may have created a dust/air layer ahead of the Bloodhound wheels on the Haskeen pan dust and drastically reduced the coefficient of friction, is my personal opinion.

Management of the tire to surface boundary layer is critical for a wheel steered vehicle.  There is some data about the above between tires and asphalt or concrete surfaces.  There is less about other surfaces and especially if the dynamic aspects are considered, and none I could find when pondering the rotating atmosphere and shock wave effects.
       

      .     

[wobblywalrus]

The tire to surface interface needs to resist forces from the engine powering the bike, braking, cornering, and wind.  Cornering and braking loads are minimal at the salt flats.  The resistance to sliding is provided by a combination of vertical load multiplied by the friction coefficient.

Tire selection.  Tires need to be up to correct operating temperature to provide grip.  The salt is a relatively cool surface compared to pavement.  Most DOT street tires, flat track tires, and road racing rain tires, and soft slicks grip at these temperatures.  Some street tires, and intermediate or hard race tires will not get hot enough to grip unless spun.

The salt surface is more like a flat track than it resembles pavement.  Some grooving is beneficial.

As per the Triumph.  One piece wheels were fitted this year with a 19-inch front and 17-inch diameter rear.  Bridgestone Battleaxe DOT tires with (W) ratings are fitted.  They grip well at salt flat surface temps and have some tread grooves to provide grip and to evacuate water.

Another tire combination that provides more open tread area and grips at salt flat surface temperature is a flat track front tire with a racing rain rear tire.  They are available in the 19 front and 17 rear sizes.  That is probably a better combo than the battleaxes for anything but the smoothest and hardest salt.

Friction coefficient and speed rating are the primary things I look at during tire selection.