Landracing Forum Home
November 19, 2018, 05:23:51 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with username, password and session length
News:
BACK TO LANDRACING.COM HOMEPAGE
 
   Home   Help Search Calendar Login Register  


(Note: Donations are not tax deductible)







Live Audio Streaming and Archives of Past Events
Next Live Event: TBD
Pages: 1 ... 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 [53] 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 ... 215   Go Down
  Print  
Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 703562 times)
0 Members and 1 Guest are viewing this topic.
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #780 on: May 31, 2012, 12:03:12 AM »

The tach is installed in the very front of the fairing just under the windshield.  A better location than before.  Maybe I will read it now.  The fairing is done except for cleaning it up and sanding and polishing the windshield.

The drag that keeps me from getting that red hat is a combination of friction and aerodynamic resistance.  The aero drag can be expressed as frontal area x coefficient of drag.  The new fairing has much more frontal area than me sitting on the bike or the old fairing.  The only way I can compensate for this is to drastically reduce my coefficient of drag.  Metal mutilation starts on the bike's back end now.  I need to get this right in order for everything to work.

 


* Fairing Rebuild 152.JPG (233.73 KB, 800x535 - viewed 179 times.)

* Fairing Rebuild 153.JPG (205.2 KB, 600x731 - viewed 181 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #781 on: May 31, 2012, 09:56:26 PM »

The task now is to examine the bike sides and to remove anything extraneous that hangs out into the wind.  The goal is to minimize the separation of airflow from the fuselage and consequently, to lessen the turbulent wake.

Somewhere in the FIM regulations I read about the number plates being made from unbreakable plastic.  I made some with the thought it was required.  Lots of FIM racers, including the one that beat my old record, simply paste the numbers onto the fairing or tail sides.  I am clearly guilty of excessive thinking.  The plastic number plates went into the recycle bin and I will paste everything onto the sheet metal.  There is no shortage of that, as shown in the pix.   


* Fairing Rebuild 154.JPG (179.81 KB, 800x533 - viewed 236 times.)

* Fairing Rebuild 155.JPG (176.94 KB, 800x533 - viewed 229 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #782 on: June 05, 2012, 11:49:24 PM »

Sparky, the gearing statistics for the Triumph.  Hopefully this is what you need.

Tire slip is 2% for dry tight salt, 5% for damp tight salt, 7% for wet loose salt, tire circumference is 79 inches (steel belted radial, hardly any growth), final drive is 19 tooth drive sprocket with 40 or 38 tooth driven sprockets, fifth gear ratio is 1.07 to 1, fourth gear ratio is 1.29 to 1, primary drive ratio is 1.74 to 1, target rpm is 7,500, redline is 8,400. 
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #783 on: June 07, 2012, 12:02:50 AM »

The rules for AMA and BUB require that I run AMA streamlining regardless of whether or not I am running for a record.  The big reason for running this year is to try out the streamlining for the Australia trip.  I need to make sure everything works OK, figure out suspension settings and gearing, and get data to calculate the drag coefficient.  The AMA tail skirting is minimal and running AMA will not give me the experience and data I need.  Running FIM would work.  It is a lot of money and I do not have it.  RWB, run-watcha-brung, will be my class.  It is a short course class.  One mile to get up to speed, one mile timed, and one mile to shut down.  This is enough length for what I need to do.

Any streamlining work requires the rules to be handy along with tin snips, hammers, coffee, etc.  The future for me is RWB, DLRA, FIM, and maybe USFRA.  The DLRA and FIM rules are what I am building for now.

The Arrow pipes I was using had large megaphone shaped silencers that stuck up and out.  They were bad for aero.  Some smaller and more streamlined silencers will be fitted.  The shiny and triangular lower sheet on the skirting is added.  This area was occupied by the bulky Arrow mufflers.  This added skirting should be a big help.

This is an FIM tail.  It does not project more than 1/2 the rim diameter past the rear tire.  At least 135 degrees of the rear wheel is visible from the side. 


* Fairing Rebuild 156.JPG (162.21 KB, 601x451 - viewed 152 times.)

* Fairing Rebuild 157.JPG (239.74 KB, 800x584 - viewed 178 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #784 on: June 10, 2012, 11:19:28 PM »

Cooler air in the intakes make more power.  The air filters are inside of the seat tail unit and there is hot air in there during runs.  Some cutouts and slots let cool air into the filters.  The back end is braced to prevent fluttering.


* Fairing Rebuild 158.JPG (233.76 KB, 794x600 - viewed 155 times.)

* Fairing Rebuild 159.JPG (196.74 KB, 639x600 - viewed 136 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #785 on: June 10, 2012, 11:32:52 PM »

The DLRA allows the tail to extend up to 10 inches beyond the rear tire.  This is 1.5 inches more that the FIM limit.  The tail is extended this amount.  It is made so the 1.5 inch extension can be quickly removed when I run FIM.

The tail can extend down to four inches above the salt with the rider seated according to DLRA rules.  It seems to be a good idea to have the tail this low if the bike has low streamlining ahead of it.  Mine does not.  The shrouding for a low tail would catch a lot of wind and it might affect the handling.  I kept the tail shrouding above the rear axle.

The entire tail section including the seat pad weighs 20 pounds.  It weighs much less than all of the touring gear that is removed when it is fitted.  This has been a lot of work.  The tail is done.  Exhaust tuning is next.     


* Fairing Rebuild 160.JPG (239.34 KB, 800x533 - viewed 155 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #786 on: June 13, 2012, 12:25:31 AM »

Exhaust tuning is the last task of the year - except for putting everything together, going to the salt, racing, and squeaking past the 140 mph barrier.  This build diary addresses basic stuff.  This theme is followed for exhaust tuning.  "Performance Automotive Engine Math" by John Baechtel is used as a reference.

Two of many things to worry about in exhaust tuning are flow and sonics.  A big river is an analogy.  We watch if flow by us from the shore.  The water always goes in the same direction.  Its speed and flow are governed by channel characteristics such as size, gradient, and smoothness.  There are waves on the river.  Wind waves going one way, boat wake waves another, and waves from a tossed rock following a different path than any.  The waves travel quickly in any and all directions regardless of flow direction.  This is like the sonic waves in the exhaust system.

First, is the header I am using is the right size?  It worked good on the 790 cc engine.  Will it be OK for the 865 and 994 cc motors?  The procedure is to analyze it using three methods that were developed independently from each other:  Baechetl's formula, A. Graham Bell's method, and Meaux Racing's PipeMax program.  (Baechtel Chapter 8.)

Baechtel's relationship says that primary pipe diameter is related to the amount of exhaust that must pass through it, and this depends on cylinder volume and rpm.  This makes sense.  The attached pages show the calcs for the three motors.  The pipes I have are 1.40 inches diameter, the 790cc engine needs 1.50 inch pipes, the 865 cc one requires 1.57 inch ones, and the 994 cc needs 1.68 diameter tubes.  Clearly, the headers I am using are too small.

How much too small?  Looking at diameter and comparing the standard Triumph pipes to the ones needed for an 865 cc engine:
[(1.57 - 1.40) / 1.40] x 100 = 12%, not much smaller.  This is misleading.  Flow capacity is related to cross-sectional area.  Looking at area and comparing the standard pipes to the ones needed for an 865 cc engine:  [(1.95 - 1.58) / 1.58] x 100 = 23%.  The pipes I am using are 23% too small when looking at area.  Sometimes it is a good idea to take a good look at how things are compared to each other.  The next post will be about Bell's method.

       



 


* Exhaust Tuning 16.jpg (221.46 KB, 768x1009 - viewed 173 times.)

* Exhaust Tuning 17.jpg (222.75 KB, 768x1011 - viewed 163 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #787 on: June 13, 2012, 10:21:17 PM »

The A. Graham Bell equations as presented in Baechtel's book were problematic.  The Bell formulae I used were from some old notes and they are shown on the calculation sheets.  The answers from the note equations are more consistent with the PipeMax results and Baechtel's equations.  The Bell equations also show that I need bigger diameter headers.

The Bell formulae are familiar.  Baechtel's equations and PipeMax are not.  My usual method is to use both the old stuff I am used to, alongside the newer methods, until I am comfortable with the new.  Another thing I do is analyze my last good engine as well as the motor I am working on.  The old engine is a good reference point.  All of this is extra work and it pays off in the long run.  It helps me to spot errors and mistakes and to recognize useful trends.  The PipeMax analysis is next.   


* Exhaust Tuning 18.jpg (222.75 KB, 768x1011 - viewed 170 times.)

* Exhaust Tuning 19.jpg (265.69 KB, 768x1009 - viewed 150 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #788 on: June 14, 2012, 11:41:01 PM »

The March dyno work was to sort out the spark advance curve and the intake and exhaust systems.  A slipping clutch stopped everything before the exhaust could be done.  The jetting curves for the selected advance curve and intake system are shown.  The # 145 jets were chosen with 72.56 hp at 6800 rpm and 60.37 lb-ft torque at 5,500 rpm.

This dyno session was set up to be as close as possible to the March one.  The same dyno, operator, tire, tire pressure, chain, sprockets, etc.  Neither time was the bike cinched down on the roller.  The fuel was premium non-ethanol unleaded purchased from the same pump at the Lincoln country store.  We forgot to set the correction factor to SAE on today's work.  It is SAE on the March pulls and Standard on today's.  The big difference was the exhaust system.  A set of Arrow 2 into 2 pipes with no baffles was the March setup.  Today's setup was some old stuff from my bone pile.  All of the mufflers in my junk heap are rusted out so I had to buy a new pair.  Oh the agony.. I had to purchase something.

Jetting pulls are shown.  We chose the #135 jets with the brown curve.   84.83 hp at 8,400 rpm and 60.52 lb-ft torque at 6,500 rpm.  The engine wanted to pull higher than 8,400 rpm.  The rev limiter prevented this.  I am sure glad there are Arias pistons and Carillo rods in this thing.

Posting attachments is troublesome this evening.  The charts will be on the next post or on a post tomorrow.     
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #789 on: June 14, 2012, 11:41:38 PM »

The dyno graphs.
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #790 on: June 14, 2012, 11:46:05 PM »

Another attempt at posting the graphs.


* 2012 Dyno Session 112.jpg (154.95 KB, 768x1002 - viewed 163 times.)

* 2012 Dyno Session 113.jpg (152.38 KB, 768x969 - viewed 158 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #791 on: June 16, 2012, 06:39:37 PM »

The data is collected for PipeMax.  The preliminary volumetric efficiency estimate is 100%.  The Triumph cam data was at 1 mm lift.  I had to plot out the lift vs duration curves on graph paper and figure out what they would be at .050 inch lift.  It is very important to do this.  The lobe center angle is in cam degrees.  See the camshaft chapter in Baechtel's book and he will explain this.

Calculating the volumeteric efficiency to match the dyno'ed horsepower is the first task.  My readings are from a chassis dyno.  A common assumption for bikes is a 10% loss in engine horsepower for the drive train loss and the tire to dyno roller loss.  The chassis dyno hp is multiplied by 1.1 to estimate engine dyno results.  I need to do this.  The data used to develop PipeMax is from engine dynos and I need to enter engine dyno hp to get the program to work right.

The data sheet for the 790cc engine is shown.


* Exhaust tuning 20.jpg (284.93 KB, 768x1009 - viewed 143 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #792 on: June 16, 2012, 06:47:07 PM »

The "calculate torque and horsepower" option is chosen in PipeMax.  The volumetric efficiency (VE) reading is changed a percent at a time and the program is rerun.  When the horsepower calculated by PipeMax matches what I got on the dyno (corrected to engine dyno) readings, I am done and ready for the next step.  The little motor is estimated to have had 108 percent VE.  This is a reasonable value considering its state of tune.


* Exhaust Tuning 21.jpg (245.83 KB, 768x901 - viewed 152 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #793 on: June 16, 2012, 11:55:47 PM »

The Triumph uses a single pipe with a muffler for each cylinder.  This most closely resembles a primary pipe for a header.  The PipeMax recommendations are shown.  Note the recommended pipe size and the harmonic lengths.


* Exhaust Tuning 22.jpg (244.72 KB, 768x840 - viewed 145 times.)
Logged
wobblywalrus
Hero Member
*****
Offline Offline

Age: 65
Location: backwoods Oregon
Posts: 4755





Ignore
« Reply #794 on: June 16, 2012, 11:59:54 PM »

The pipe and the harmonic lengths are plotted on this graph.  Note that the cross-pipe between the headers is located very close to the most desired harmonic length.  Also, the headers are a bit large for the little 790 cc motor.  This system worked very well for that engine.


* Exhaust Tuning 23.jpg (297.15 KB, 1024x766 - viewed 164 times.)
Logged
Pages: 1 ... 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 [53] 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 ... 215   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines
Simple Audio Video Embedder
Valid XHTML 1.0! Valid CSS!


Google visited last this page July 28, 2018, 03:06:34 PM