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It's a Drag #545037 05/24/14 12:12 pm
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Ron - in California R.I.P. Offline OP
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OK, one important aspect of going fast (in some kinds of racing) is the aerodynamics - drag. And on an LSR, this is possibly far more important than getting a few extra H.P. This is a subject I have limited knowledge on.. but my dyno guy even mentioned it to me.

So, in LSR you have different classes, which dictateds what you can and can not do. But even in a production class, I bet there are things you can do... I suspect even a slight change in a headlight angle can bring more speed.

For me, my main goal for this August is to get above the 100 MPH lap speed on the IOM. When I think of all the turns and spots where it is not possible to go 100 MPH, this has to be offset with spots above 100 MPH to get to that average. ore power helps, better handling helps, better brakes help.. but if I can reduce the drag a little bit, then a few more MPH can be had in the fast spots.

Here is a good essay from pal Tony Foale. http://www.tonyfoale.com/Articles/Aerodynamics/AERO.htm

Here is another article.. http://www.yamaha-motor.eu/designca...es/index.aspx?view=article&id=442628

So using a true wind tunnel is not within my budget.. maybe next year (also out of time anyway). Yesterday I was taking my new front wheel to a pal to do some work on it.. On the way, there was a pick up truck. In the bed was a 50 gallon trash can, the plastic kind with a hinged lid. The lid opening was facing backwards yet the air was lifting it about 4 inches. Aha.. we all know that the wind currents form a negative pressure zone. And that causes drag in a pick up truck, It is old knowledge that even opening the tail gate will increase the fuel economy a little bit. Drag gets reduced.

I am wondering what I can do to simulate wind drag on my bike..? Perhaps I can rent a large commerical fan for a few days and play with it.. who knows..? I can tape some bits of paper to spots on the bike and see how even a smallish fan can show me what is going on. Obviously having a rider sitting on the bike is part of the equation.

H.B, not sure if you have gone down this road.. but.. there may be a lot of speed with reduced drag..! Heck even narrowing the handle bars (or clip ons) can reduce drag..

Ron

Last edited by Ron - in California; 05/24/14 12:15 pm.
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Re: It's a Drag [Re: Ron - in California R.I.P.] #545054 05/24/14 3:40 pm
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Yes, the air is your enemy.... My bike is in Modified Production where no aerodynamic aids are allowed except for front fender design.Experienced guys say messing with a fender is for much higher speeds then us..The class rules allow a headlight but I have no idea if it really helps or not other than the bike's fastest time was with a small headlight...But there's many other factors...
The clip on grips are just above a front tire as is the seat just above the rear tire right on the class rule low limit.The bars are pulled back so they just clear the small fuel tank with the lock reduced to 1/2 of normal.The bike is lowered about 2 inches,the rear set pegs with in a few inches of the rule limitations.
The biggest lump in the wind is the rider. He's 6 foot with an athletic build,maybe 185 pounds. I'm much older ,6 foot about 165 pounds. On the bike he's gotten pretty good at making himself smaller than I can.
A 5 foot 3 inch 120 pound rider is probable the best improvement.AKA a woman grin
A Brit racer told me to have the rider on the machine in front of a white wall or sheet.Then use a bright light to cast a shadow . The rider can practice moving around to minimise his profile.


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: It's a Drag [Re: Ron - in California R.I.P.] #545107 05/25/14 12:31 am
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noisy norton Offline
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Hi Ron, Happy to hear you are headed for the Island again. I've been harping for years about drag. Running small capacity engines mean quite simply that you have a limited amount of power. And a machine will produce a certain amount of drag. Which in turn gives a finite amount of speed. The only way to go faster is to reduce drag or try and squeeze more power out of the engine which can reduce reliability. In land speed racing there is a genius named Jack Costello. His favorite phrase is "Its not as important how you open the air as it is important how you close it behind you". But you already know that after watching the trash bin. Jack doesn't have a wind tunnel but he does have a leaf blower. The tried and true bits of wool thread taped to his vehicle and he observes how the wind flows across his cars. Seems to be very effective. He has a ton of hidiously fast records at El Mirage and Bonneville. Tape some long wool thread on your riders back and butt. And when he is tucked in hit him with the leaf blower and observe how the wool tufts behaves.

Getting the air off the rider as cleanly as possible on what is basically an open machine is difficult. One of the things that can help is a larger streamlined seat hump. It may not look pretty but pretty doesn't win races. It all depends n what the rules allow. The SCTA rules, with the exception of the streamliner classes tend to be very specific. One of the things that have stuck in my mind is what Fergus Anderson said many years ago when racing Guzzis. He said once you get tucked in don't move about. It disturbs the air. Finding the ultimate tuck for your rider is important.

Sidecar streamlining rules for LSR are fairly loose in spots and very tight in other spots. I've been trying to stretch them as much as I can. The Weslake is only 540cc with a couple of pushrods. Not being in the Francis Beart league of tuning I have to try and work in other ways.

[Linked Image]



God rides a Triumph but wishes it was a Norton.
Re: It's a Drag [Re: noisy norton] #545123 05/25/14 6:50 am
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Here's a typical high record speed naked frame modified production bike built to ECTA/SCTA/LTR rules. 1000 cc Moto Guzzi.Basic rule is stock based frame and engine. The front fender is the limit of the rules for aerodynamics..Not a small rider,not a small bike,lot of pushrod power, 158 MPH record holder.


[Linked Image]

This is the late Bill Warner's bike that is/was the world's fastest true motorcycle anywhere.True bike is one that the rider sits on not inside and has traditional motorcycle controls and layout. Standing start 1-1/2 mile on pavement, 311 MPH. He had gone about 280 MPH in the one mile and was trying to exceed 300 MPH when he suffered a fatal crash last year.
Besides the full streamlining,the Hayabusa turbocharged/exotic fuel engine has 1000 hp, think of it being powered by twenty 650 Triumph or BSA engines grin ...No doubt that power can Trump the wind.

[Linked Image]

This is a late model sport bike record holder LSR machine in modified production. 1000 cc ,182 MPH. Looks like very little was done to cheat the wind other than good engine tuning. It seems on naked frame bikes the rider's position is the most important.

[Linked Image]

This is what my Triumph shows to the wind. Considering the supposed power and the low riding postion, it's not all that much faster than more stock appearing bikes with similar power.I even adapted a folding Yamaha 650 kick lever so the riders can tuck in better.So I'm thinking my rider needs to improve his style....My bike has the record at 120 mph into a mild headwind...At the time it had 50 rear wheel HP on a eddy current dyno...I think it should be a bit faster at that power level...Or the dyno reading is bogus or I'm underestimating the power needed to push it through the air..

[Linked Image]


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: It's a Drag [Re: Ron - in California R.I.P.] #545184 05/25/14 4:05 pm
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noisy norton Offline
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The Guzzi belongs to good friend Bill Ross. 158 naked. He added an Airtech "Charlie Toy" fairing and seat and ran 170 with the same bike.

[Linked Image]

Alp Sungertekin brought out his new A/VG 650 Triumph. The frame is very compact. Beautifully done. He ran 139.22 for a new El Mirage record. Alp spent a lot of time figuring how much he could get out of the wind.

[Linked Image]


God rides a Triumph but wishes it was a Norton.
Re: It's a Drag [Re: Hillbilly bike] #577974 12/25/14 1:03 am
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kevin roberts Offline
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Originally Posted by Hillbilly bike

[Linked Image]


okay.

you're not running a front brake.

what do you do with that brake lever up on the right handlebar?

is this a dumb question?


every day you do not take a chance is a day of your life that you will never get back.
Re: It's a Drag [Re: Ron - in California R.I.P.] #578007 12/25/14 11:12 am
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David Dunfey Offline
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Kevin,

It is not unusual to run a cable operated rear brake.

David

Re: It's a Drag [Re: David Dunfey] #578013 12/25/14 12:14 pm
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Ron,

It is not easy to streamline a road racer. As HB says your best bet is the rider. The smaller the better. With the chosen rider in position on the bike you then have to modify the components that allow the rider to "disappear" on the bike. This means that the elbows, knees and feet are tucked in so that the widest components are the those of the bike. The helmet would be all that is seen on top, maybe some shoulder line. The smaller the helmet the better. I believe it is worth looking at the rider in position and examining the leathers for smoothness and it may be necessary to have some purpose made or altered for the task.

You can calculate the frontal area either by computer or the garage door method. Use a camera for the computer or for the garage door method, set up a spotlight at night pointing at the bike with the garage door behind. The light and/or the camera have to be positioned to minimize the parallax, so a good distance away. The rider must be in place with gear on. With the photo put a gridline on based on a known measurement. With the garage door trace the outline, then do the same with a grid. You can then look at each square and do an area calculation.

I am not sure that the yarn and fan will help you. Some say it does not work at all, but I would guess that it works best with faired surfaces. The jagged surface of a bike and rider would just yield a lot of turbulent tufts.

If you want to measure you progress I would consider a coast down test. There are formulas that will convert the data to CD. There are also data loggers that do the same thing, although I have never used one.

http://www.veypor.com/veypor.html

On the mechanicals:
If you are going for top end, the flywheels should be as heavy as possible. If they have been lightened or they are stock they may not be heavy enough to get maximum top end.

Gearing is crucial. If you have not done cascading torque graphs you will be loosing time. I think that John mentioned this in another thread.

David

Re: It's a Drag [Re: David Dunfey] #578015 12/25/14 1:24 pm
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kevin roberts Offline
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Originally Posted by David Dunfey
Kevin,

It is not unusual to run a cable operated rear brake.

David


yes, i thought of that, but i don't think tony has ever posted a photograph of this machine from the left side, so i couldn't tell.

very narrow silhouette, as it is.

Quote
If you want to measure you progress I would consider a coast down test. There are formulas that will convert the data to CD. There are also data loggers that do the same thing, although I have never used one.

http://www.veypor.com/veypor.html


veypor is out of business, and will only support previous customers. no new units.

Last edited by kevin; 12/25/14 1:27 pm.

every day you do not take a chance is a day of your life that you will never get back.
Re: It's a Drag [Re: David Dunfey] #578020 12/25/14 2:10 pm
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Kevin,

Thanks. I did not follow Vepor's business. I would just use the formula, but there are lots of other data loggers and spread sheets to help out:

http://www.precisionautoresearch.com/RDP/PAR37.htm

These guys provide work books.

David

Re: It's a Drag [Re: David Dunfey] #578021 12/25/14 2:11 pm
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Pete Suchawreck Offline
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Yup, that is a cable operated brake

Last edited by Pete Suchawreck; 12/25/14 2:13 pm.
Re: It's a Drag [Re: Ron - in California R.I.P.] #578032 12/25/14 3:29 pm
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kevin roberts Offline
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david, thank you for that. i'm going through them now.

there's another possible data logger that can provide the raw numbers to use in spreadsheets like the one you suggested:

http://www.gtechpro.com/rr_fanatic.html

they make a street and a road race unit, but only the road race version will download data to a PC.



every day you do not take a chance is a day of your life that you will never get back.
Re: It's a Drag [Re: Pete Suchawreck] #578033 12/25/14 3:31 pm
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Originally Posted by Pete Suchawreck
Yup, that is a cable operated brake


what's the advantage of going that way, pete? seems like it might weigh about the same as a pedal-and-rod, and the levers poke right out into the airstream.


every day you do not take a chance is a day of your life that you will never get back.
Re: It's a Drag [Re: kevin roberts] #578055 12/25/14 8:08 pm
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Kevin,

I know in my case I added a brake lever above the clutch lever on the road racer. I only had 11" between the pegs and the top of the seat. This meant I could not flex my ankle far enough to get sufficient pressure on the foot pedal, which as already low because of the primary cover. It all worked fine, but I eventually increased the seat height and I could go to a pedal.

On the Bonneville bike I think it is a safety issue. Make it the way the rider is most comfortable or likely to react in an emergency situation. It is difficult to know the aerodynamic impact. No one documents naked bikes in various configurations in the wind tunnel. I think you just have to go with common sense by tucking the bars in as much as possible and keeping the cable runs clean.

David

Re: It's a Drag [Re: Ron - in California R.I.P.] #578076 12/25/14 11:01 pm
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that all makes sense to me, david. i'm trying hard to visualize me folding myself up into an 11-inch hairpin, though. i'm running clubman rearsets, with clipons set as high as i can get them on my bonneville, and i already run into interference between my thighs and (overlarge) middle when i ride it. i'm going to try to keep the clip ons but come up with rear sets that keep me as low as i am now but let me extend my legs a bit farther back.

on the brakes it seems like installing a cable setup would likely be easier than a foot pedal. i once constructed a throttle assembly for a hot rod hudson out of bicycle brake components, and there were lots of cable configurations available.


every day you do not take a chance is a day of your life that you will never get back.
Re: It's a Drag [Re: kevin roberts] #578116 12/26/14 10:11 am
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Originally Posted by kevin
Originally Posted by Pete Suchawreck
Yup, that is a cable operated brake


what's the advantage of going that way, pete? seems like it might weigh about the same as a pedal-and-rod, and the levers poke right out into the airstream.


The hand operated rear brake gives readily available braking control when loading or unloading the bike from a truck with a ramp. I believe the riders gloved hand is more wind drag than a lever...
The brake isn't normally used during the LSR racing, the rider just sits up into the wind and engine braking.
I have since reevaluated my riders ability and now think he does just a great job. I mean the bike has only made a total of 10 runs on the track so he has learned.
I've shown this video before but just watch how easy the rider and machine gets up to 125 mph.I believe 130 MPH is within reach without touching the engine

https://www.flickr.com/photos/[email protected]/15430128095/





79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: It's a Drag [Re: Hillbilly bike] #578126 12/26/14 11:22 am
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HB,
All that gets me, is to an ad about flickr...

Re: It's a Drag [Re: Rickman] #578141 12/26/14 1:26 pm
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Should be ok now..


79 T140D, 96 900M Ducati ,2001 Sportster....On a bike you can out run the demons..
Re: It's a Drag [Re: Ron - in California R.I.P.] #578143 12/26/14 1:44 pm
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Ron,

I think Noisy Norton aside from providing a great photo of his rig, has an important point with the mention of Fergus Anderson. I know that Dave Mattson mentioned that he practiced his tuck in full gear in front of a mirror. He would examine everything and make adjustments: toes in, shoulders down, knees tight to the bike, etc. He would practice the tuck until he felt he had good muscle memory and repeat it on the salt. This also involves checking for comfort which is critical for stamina.

I think he is also right about the seat hump and front fender, but it will be up to the rules as to what you can run. In general, it seems that the rider's back slopes too much to the seat hump. The flatter the back the better it is in the wind. This may be an area where a taller seat can help. If you look at the video, even though this is a faired bike you can see that most of the disruption occurs around the rider's back and the flat panel (and air intake). The flow also separates at the tail. You cans see the tight plume of smoke as the wand is raised high and how chaotic it gets as it is lowered. You can't get good laminar flow over a naked bike (like you see on the front of the 125), but you can visualize what will help it out considerably.

https://www.youtube.com/watch?v=zG8Htax6_Og&feature=youtu.be


David

Re: It's a Drag [Re: Hillbilly bike] #578173 12/26/14 7:06 pm
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kevin roberts Offline
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Originally Posted by Hillbilly bike

The hand operated rear brake gives readily available braking control when loading or unloading the bike from a truck with a ramp. I believe the riders gloved hand is more wind drag than a lever...


that is a good idea.


every day you do not take a chance is a day of your life that you will never get back.
Re: It's a Drag [Re: Ron - in California R.I.P.] #578189 12/26/14 9:31 pm
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I've been trying to reduce drag as much as I can. As I've said before, you can only get so much power out of an engine. Reducing drag, for me, is the only alternative. I don't have a wind tunnel. I use the photos from El Mirage to see what is going on behind the sidecar. Looking at the video David posted I was fascinated by the smoke when he held it behind the bike. Amazing to see so much disruption of the smoke.

The original body I built seemed to work good. Not a lot of dust behind.

[Linked Image]

Thinking if I stretched the body to cover the rear wheel and extend it, it would smooth out the air flow. Instead I found myself towing a big ball of dust right behind the back wheel. I cut a lot of the body away and it seems to have helped.

[Linked Image]

It would be interesting to get into a wind tunnel and see what is really going on.


God rides a Triumph but wishes it was a Norton.
Re: It's a Drag [Re: noisy norton] #578279 12/27/14 8:26 pm
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Some more ideas for you to contemplate. Naked and fully faired. Covering the rear wheel was allowed for the first time in 2014 at AMA/Bonneville Motorcycle Speed Trials. The bottom line - - get down and make yourself small!
[Linked Image]
[Linked Image]
[Linked Image]
[Linked Image]


Life's uncertain - go fast now!
Re: It's a Drag [Re: Ron - in California R.I.P.] #778676 07/15/19 12:49 am
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kevin roberts Offline
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snippets in no particular order

Exhaust should be directed as aft as possible and into a "low pressure"
region if possible (such as the wake of the vehicle)....


If your going to modify the hand-fore-arm part of the fairing...........think about turning the 'grips' downward which will rotate the riders elbows and shoulders to a much more narrow profile.

Temp goes up, density goes down and so does drag.

However if pressure goes up it increases density and drag.


Last edited by kevin roberts; 07/15/19 12:54 am.

every day you do not take a chance is a day of your life that you will never get back.

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