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Between 265 & 485 SQ/FT The 12-Gauge Garage

Workspaces sized between 265 and 485 squarefeet.

Zengineer

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Apr 10, 2010
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British Columbia, Canada
Yes, it's a diffuser on the rear end of the underside of the car. I was experimenting with a design that generates a lot of downforce for prototype race cars. Unfortunately, production cars are sprung too softly for it to work consistently -- especially in corners, which is where you'd need it.

Jack, Jack, Jack! Attach it to the suspension, not the body. ;) Who cares about spring rates!
 
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Omphaloskeptic

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Ultima Ratio, Wa.
Dang, I was just kidding about the wind tunnel. You really have done your homework on airflow; and I'll bet you really did wax the underside! LOL
Next, Jack will be fitting up wheel well spats and using flush rivets on the under body.

:bounce:
 

couchmechanic

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Bakersfield
Nice aluminum work, I like the looks of the underside. Can you feel a difference when you get into dirty air? Say like when your behind another carfor example.
 
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Jack Olsen

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Jack, Jack, Jack! Attach it to the suspension, not the body. ;) Who cares about spring rates!
Chaparral designer Jim Hall would agree. Unfortunately, with a 911's semi trailing arm suspension, that's easier said than done. But I've tested some crazy stuff.

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Dang, I was just kidding about the wind tunnel. You really have done your homework on airflow; and I'll bet you really did wax the underside! LOL
Next, Jack will be fitting up wheel well spats and using flush rivets on the under body.

I've tried a lot, including front canards -- and even winglets instead of traditional end plates.

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The front wing didn't work. The canards did. The winglets might have reduced drag, but I couldn't get any numbers to show any benefit in testing.

Nice aluminum work, I like the looks of the underside. Can you feel a difference when you get into dirty air? Say like when your behind another carfor example.

That's a good question. I haven't noticed it. Maybe because the parts of the track where aero is doing the most good (high speed sweepers) is also where you tend not to be following in really close formation. But it probably also has to do with the fact that aero on a production car is not effective in the same way it is on F1 cars or race prototypes.

My home-made diffuser worked in a straight line -- I got ride height data that proved it. But it would lose its effectiveness when the body of the car rolled in a corner. That sort of underbody aero is very sensitive to its relative position to the track surface. In the first day of testing it, this happened:

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That looks pretty bad. In fact, it was just a quick spin. Here's a video clip of what it looked like from the driver's seat.
 
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Dennis Cavallino

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The Netherlands
The combination of the huge rear wing, loose-911-front and diffuser will always generate a lot of understeer I assume, especially when you have too much entry speed.

To drive with real downforce you must drive faster around corners than you are used when to not driving a car with downforce. Otherwise it doesn't work. A 935 RSR front will help a bit probably? Although I think it didn't run with a diffuser ever, because the engine compartment was open to mount/cool the turbo's at the rear. A diffuser makes a huge different.

Downforce = way beyond most people's skills, especially when it comes down to racecars with too many parameters that makes most of us confused. Corners, hills, bodyroll, drag from the cars in front, wind, etc. all have to be tested irl instead of a windtunnel or computersimulator. It's funny to see our Jack does just that, just because it can be done by doing it. :)
 
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Jack Olsen

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Here's today's wing work. This is a test mule to see if the foam cores used by RC aircraft enthusiasts would work as a rear wing on my track car. A lot of what you're going to see is ugly, so be prepared. :)

Here's my old wing in use. It comes apart into two pieces to fit in the car, but over the course of five years the junction point got too stressed and was no longer perfectly straight.

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Here's the five-years-used wing sitting next to the test core. I will use a different airfoil profile for the final wing. This is one they had ready on the shelf.

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My quick way to cut the support pieces is to draw them on a piece of paper, cut them out with scissors, and then lay them flat on the final material -- and spray paint a silhouette to transfer the pattern.

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There's an aluminum tube that I'm running the length of the wing, for strength. One of these two L-pieces will connect to it. The other will be sttached to the wing, and also to a sheet of aluminum that is also attached (with structural adhesive) to the foam.

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I had to set threaded sleeves into the pieces at the end so I can attach end plates later.

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Anything and everything gets used for clamping the material while the adhesive sets.

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Did I mention it's a test mule? The cutting here is very crude. But you can see where that L-shaped piece went. It also gets a rivet to connect it physically to the tube. But the adhesive I'm using (3M Scotch-Weld DP-110) is stronger than the material it's connecting.

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I still need to skin it -- maybe with thin aluminum, I'm doing some tests for that overnight. But here it is test-fitted on the supports. I hit the aluminum parts with spray paint. There are no end plates on in the picture, but you get the idea.

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Jack Olsen

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Ha!

I'll tell you, working with this foam insulation stuff is a LOT easier than what I did with the previous wing. It was my first metal fabrication ever, pretty much. I was in way over my head, without any kind of model or instructions. But finally got it finished -- and it still works, five years later.

I started with a wooden buck I made from a print-out of the airfoil I wanted to use.

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On the topic of garages, you'll see that five years ago I just had to set up a little temporary bench next to the car under its canopy. At the time, the garage was so stuffed with storage and other **** that there was no room at all to work in it (much less park a car).
 
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onewaydave

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Sep 28, 2009
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Down the road from Dorothy and Toto
Very interesting stuff here, Jack. Your sheet fab with the aluminum foil is cool. I also like the nostalgia of hearing Hall's name mentioned. But...

I came to ask an off the track question about the garage. I saw in another thread the rotary phone on the wall. Is it functional, rebuilt for digital or decoration?

Dave.
 

J.Lind

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Sep 14, 2011
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Everett, WA, USA
I quite love your lack of fear when it comes to trying something new with the car. A dedication to the scientific method in a very low-budget kind of way. The metal work on your rear tray looks great. You may consider ignoring an entire flat bottom, as you'll likely get just as much performance with just a front and rear tray (leaving the middle somewhat exposed) as is found on the Nissan GTRs from the factory.

You'd also gain a noticeable amount of down force in the front by extending the front tray out a couple inches as a splitter. (Kind of like this but without the brake duct holes). Oddly enough, plywood actually works really good as a front tray/splitter.

Enough thread jacking from me, but soon we'll get one of these on your car ;)
uppes.jpg
 
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flybefree

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May 18, 2008
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Ohio/Kentucky
Jack,

I'm just glad you use your gifts for the forces of good and not evil!

How did you pick the specific cross section for your airfoil?

Shaun
 
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Jack Olsen

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I came to ask an off the track question about the garage. I saw in another thread the rotary phone on the wall. Is it functional, rebuilt for digital or decoration?
It's functional. It's a 1951 Western Electric 354 that I got on Ebay. They built those things like tanks. The odd thing was plugging it in (I had to wire a plug) and calling my cell phone with it. Imagine trying to connect with your current cell phone in 6 years from now, let alone 60. But the rotary dial still works on the phone network. I had to open it to slightly mute the bell, since the neighbors' bedroom is about 30 feet from where it sits, and I don't always remember to close the garage door.

I quite love your lack of fear when it comes to trying something new with the car. A dedication to the scientific method in a very low-budget kind of way. The metal work on your rear tray looks great. You may consider ignoring an entire flat bottom, as you'll likely get just as much performance with just a front and rear tray (leaving the middle somewhat exposed) as is found on the Nissan GTRs from the factory.

You'd also gain a noticeable amount of down force in the front by extending the front tray out a couple inches as a splitter. (Kind of like this but without the brake duct holes). Oddly enough, plywood actually works really good as a front tray/splitter.

Enough thread jacking from me, but soon we'll get one of these on your car ;)
uppes.jpg

Cool. The over-the-top supports is a good illustration of how much more important the bottom of the wing's surface is on an automotive wing than the top. Are the round lumps there to function like a sawtooth gurney flap?

I do run a front splitter. And the nice thing is that it fits inside the car for the drive to the track. So this is a stop on the long drive from Los Angeles to Laguna Seca (it's at the memorial at the intersection where James Dean was killed).

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And these are at the track, where you can see the home-made splitter in action.

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I'm just glad you use your gifts for the forces of good and not evil!

How did you pick the specific cross section for your airfoil?
An aerodynamics guy from Sweden helped me choose it. The important factors were how it behaved at driving speeds, how it behaved when it went into stall, and also if it was fat enough for my clumsy hands to reproduce the shape in a home-made wing.
 
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Jack Olsen

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Skinned and finished the 'test mule' wing today. My conclusion is that I have to learn to vacuum bag carbon fiber for the finished product. The thin aluminum kinks and stretches too easily. Still, it'll work.

Size: 72" span, 10" chord
Weight: 4 lbs 12 oz.
Cost: $85, although I had the skin on hand (it's roofing flashing)

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Jack Olsen

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Are you saying you are going to put a 6 ft wide wing on your car?

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Yes. At my home track, aero plays a big role (about 1.5 seconds) in my lap times. For most newer tracks, that isn't the case. Liability concerns are the reason. But if you have sweepers or kinks that are 90+ mph corners, aero can be a big help. Especially in an early 911, which generates a lot of lift above 100 mph with nothing to stop it.

Willow Springs has a 95-mph sweeper, a 130-mph sweeper, and a couple of other fast corners (one about 85 the, other about 100). A wing helps in all four of these turns.
 

matty d

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Aug 27, 2010
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Yolo County, California
wow. thats a cool pic of your car, and nice pics of you using your famous garage!

I was flipping through magazines at the supermarket...I said to myself 'Hey that garage is the one on GarageJournal!!!' :beer:
 
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Jack Olsen

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OMG! - LOOK! - Up in the air...
It's a bird!
It's a plane!

Naaah - It's just Jack Olsen trying out his new wing!:bounce:
There was one day of testing when I was using the wool tufts and stuff. I wanted to see how the air was moving over the top and underside of the wing. So I rigged up a can of pressurized air and got some sparkly glitter stuff from an art supply store. I was so wrapped up in the testing I was doing that I never gave a thought to how crazy it must have looked on the 10 freeway in Los Angeles to see a 40-year-old car suddenly shoot out a bunch of glitter into its wake. :)

But I have very little shame when it comes to that sort of thing. For years, this is how I got extra tires to the track.

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Red Leader

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Jack,

In every single post you make, you should just throw in a random picture of a Porsche. Preferably yours. They are just such a good looking car, I never get tired of seeing pictures of them.
 

Squankum

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There was one day of testing when I was using the wool tufts and stuff. I wanted to see how the air was moving over the top and underside of the wing. So I rigged up a can of pressurized air and got some sparkly glitter stuff from an art supply store. I was so wrapped up in the testing I was doing that I never gave a thought to how crazy it must have looked on the 10 freeway in Los Angeles to see a 40-year-old car suddenly shoot out a bunch of glitter into its wake. :)


Meh. This is LA. They probably just thought, "Oh look, there goes Rip Taylor. I didn't know he had a Porsche."
 
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Jack Olsen

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How often do you get a Rip Taylor reference anymore, anyways? :)

Got to track the car today. Rebuilt motor ran great. New wing didn't fly apart, clearing the way for a 'final' (and slightly smaller) version.

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Trackside burnout.

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(Full disclosure: the photographer just happened to snap that as I drove over some old tire marks. But it kind of looks like I was acting like a teenager, doesn't it?)
 
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Jack Olsen

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I doubt it. A lot of the more sophisticated aero stuff like you see on prototypes or in F1 cars isn't useful with production cars. The shell of a street car doesn't usually manage air very effectively, so most of everything downstream of the nose tends to be somewhat turbulent. Also, underbody stuff (in spite of how often it's used as decoration) is very sensitive to its height relative to the road surface. So when the car turns (which is when you need the downforce) the body roll ruins the aero effect.

That said, you'll see I have crude vortex generators on the forward corners. The idea is to create a cyclone of air downstream which acts like those 'air walls' you see at the entrance to a grocery store. The moving wall of air keeps some of the air from migrating laterally under the car. It's like having side curtains without the risk of scraping the pavement every time you turn. And the more air you can keep form getting under the car, the better.
 

Squankum

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How often do you get a Rip Taylor reference anymore, anyways? :)

It's just how my brain works. You want dated? I bet that glitter from your car messed up the windshield of an orange 914 1.7L driven by Charles Nelson Riley as you passed him. His passenger, Harvey Korman, was equally miffed. (Imagine all the ascots or turtlenecks you need for this one.)
 

NUTTSGT

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Jack, if you had a bigger garage, I'd expect you to start building airplane kits. The amount of work you get done in a small garage is amazing.
 

hobie1dog

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Cornelius,NC
sometimes I look at your garage and just think...I give up, Jacks already set the standard, everything else will be a cheap copy, but then I get planning on getting mine just a tad closer with each new built-in cabinet, or more efficient use of workbench tops. The fun part is dreaming about coming into some serious money and just duplicating the damned place...lol

I put in another vote for Max....he NEEDS a kart, as it's the most fun he'll ever have with his clothes on.
 

Rich H.

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Nov 30, 2010
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SE Michigan
I've watched this thread for a long time, it's definitely a classic. Seems to be quite influential too, and shows such a high level of smarts and creativity.

I'm also a sucker for deals on pre-owned industrial cabinets, so that aspect of Jack's shop has hit home. Keep up the good work Jack.
 
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