Author Topic: Lakester axle farings:  (Read 12120 times)

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Offline Rex Schimmer

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Lakester axle farings:
« on: September 17, 2016, 04:15:57 PM »
I am attaching a couple of pics of the axle fairings on Steve Nelson, F/Fl lakester. These were fabricated by the guys at New Metal Customs in Santa Rosa and are based upon the original ones that I did for the car in 2014, which were on the car when it reset the 4V/FL record at the WOS in 2014 at 202 mph and put Steve in the 200 mph club. The new fairings are some what different but extremely well made and the only issue I have with them is that the leading edge is to sharp for this application.

Before our only run in 2016 (195 mph) I put drops of gear oil mixed with carbon powder along the leading edge on the top of the fairing and also along the transition area where the fairing goes over the rear axle. I also put drops of oil along the bottom side of the fairing starting from the area where the fairing has the largest section going over (under?) the axle. Regretfully Steve turned out to the left and the front wheel threw a considerable amount of salt on the top of the fairing but you can still see the oil tracks. Basically I am pretty happy with what appears the be the path of the air flow. There are no indications of turbulence or separation on either the top of bottom and I am sure compared to the drag of a round axle housing these are much better aerodynamically. In 2014 I did some quick calculations of the drag of the open axle housing vs the faired housing and the reduction in drag pretty much equaled the required hp increase required to make the speed increase from the former 197 mph to the new 202 mph record. Note that other than the axle fairings there were no other changes to the car or engine so the speed increase (I would like to think anyway) could be entirely contributed to the axle fairings.

Rex
Rex

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Offline SPARKY

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Re: Lakester axle farings:
« Reply #1 on: September 17, 2016, 05:24:10 PM »
Rex,  on the underside?   (where we see feet)  are we looking toward the rear
Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

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Offline Rex Schimmer

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Re: Lakester axle farings:
« Reply #2 on: September 17, 2016, 06:38:54 PM »
Sparky,
The second pic is the bottom rear of the fairing looking foward toward the front of the car.

Rex
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Offline SPARKY

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Re: Lakester axle farings:
« Reply #3 on: September 17, 2016, 11:40:33 PM »
hmm looks like the 'Bow Wave" off the tire is pushing the air toward the body instead of the "wackum" of the tire sucking it to the outside!
Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

We are going to explore the racing N words NITROUS & NITRO!

Offline oj

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Re: Lakester axle farings:
« Reply #4 on: November 22, 2016, 02:31:59 PM »
How about a crossectional of what a fairing should look like? 

Offline SPARKY

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Re: Lakester axle farings:
« Reply #5 on: November 22, 2016, 03:55:57 PM »
minds need to know  :-D
Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

We are going to explore the racing N words NITROUS & NITRO!

Offline oj

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Re: Lakester axle farings:
« Reply #6 on: November 22, 2016, 05:03:46 PM »
minds need to know  :-D

Seems if the leading edge were below the middle the air would either try to lift or try to push down, right?

Offline Rex Schimmer

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Re: Lakester axle farings:
« Reply #7 on: November 23, 2016, 02:01:31 PM »
Regarding the fairings shown in the pics of Steve Nelson's lakester, these were fabricated by the guys at New Metal Customs in Santa Rosa, CA. They are very well made and the fit is outstanding, the only thing that I did not care for was the leading edge as it is a combination of a sharp edge, that you can see and then a straight angle down that allows the lower skin to go below the radius rod that helps to locate the rear end. The leading edge of an aero foil shape is very important. The "original" fairings, which were on the car when it set the record in 2014 were ones that I fabricated, not nearly as pretty as the New Metal Custom fairings but their general shape was based upon the NACA 66018 air foil section with an extended nose to cover the radius rods. The radius rods are a 1 inch rod that are angled to the center line of the car at approx 30 degrees. This makes the actual shape of the radius rod normal to the direction of motion (hopefully straight ahead!) a 30 degree elliptical shape which is fairly close to the nose radius of a 66018 section of the size required to cover the axle housing. The actual shape that went over the axle housing was a 66018 section, which means that the top of the fairing and the bottom from where it increases in thickness is the 66018 section and I assume that the New Metal Custom fairing is some what the same. As you can see from the oil tracks on both the top and bottom of the fairing it certainly appears that the air is attached and flowing as we would hope that it would. My thinking is that if the axle fairings were needed to provide some aero down force I would attach some small 1/4 to 3/8 inch Gurney strips to the top of the trailing edge to increase their angle of incidence and make some down force or at least cancel any lift with minimum drag increase. I tried to get Steve to completely remove the radius rods but he was not in agreement so we integrated their shape into the fairing. I would personally not run a radius rod on the rear end as there are other ways to make it stiff enough to carry the acceleration and braking loads and this would allow the fabrication of a true air foil to cover the axle which then should be the optimal aero shape and also possibly be used to generate some down force as per what the Rob Freyvogle is doing on his streamliner.

Rex
Rex

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Offline ggl205

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Re: Lakester axle farings:
« Reply #8 on: November 23, 2016, 04:22:29 PM »
Rex, did the lakester go faster with axle fairings than it did without them?

John

Offline SPARKY

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Re: Lakester axle farings:
« Reply #9 on: November 23, 2016, 04:42:49 PM »
yes  Nelson finally got in the 2 club with them if my sr memory has crossed the border between short term to long term  8-)
Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

We are going to explore the racing N words NITROUS & NITRO!

Offline Rex Schimmer

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Re: Lakester axle farings:
« Reply #10 on: November 24, 2016, 12:07:49 AM »
ggl205,
I wrote in my first post: " In 2014 I did some quick calculations of the drag of the open axle housing vs the faired housing and the reduction in drag pretty much equaled the required hp increase required to make the speed increase from the former 197 mph to the new 202 mph record. Note that other than the axle fairings there were no other changes to the car or engine so the speed increase (I would like to think anyway) could be entirely contributed to the axle fairings."

Rex
Rex

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Offline Jim Phelps

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Re: Lakester axle farings:
« Reply #11 on: December 12, 2016, 09:23:51 PM »
It looks like a NACA 66018 air foil section, but it is put on backwards with the section trailing edge as the leading edge and the rounded front is used as the trailing surface on the vehicle.

The flow seems to be attached past the point of maximum thickness, so there should be significant drag reduction. But there is separation where the streak lines stop on the surface.