[dbostrom]

The employment of wheel "pants" on light aircraft with fixed gear and varying levels of performance might be a helpful indicator here. As well, it's maybe relevant that some larger aircraft (737 for instance) have main gear that are exposed and only semi-flush when retracted; air carriers are rather obsessed with fuel economy yet apparently the engineering trade on exposed wheels is still worth it.

For light aircraft many owners report a 4-5 kt increase in speed for a given manifold pressure when equipped w pants, but that's at speeds of significantly more than 100+ kts.

Brake cooling I suppose could be a factor in choice, although it's unlikely to be an issue with the Bolt.

It's a shame that there's really no way to get the kind of numerical data that would be useful in edge cases like this, without aggregating data from say 100 owners with the exact same treatment over a long period of time. Anything short is anecdote because of variability in the environment experienced by individual vehicles.

What we need is an old dirigible hanger with a track. That would make single-vehicle testing more possible. Drive round and round with cruise control, following a painted line. But maybe that's unhealthy.

 

[DaV8or]

I'm sure the people who drive the speed limit in the left lane tell themselves the same thing.

One problem is that speed limits here in the U.S. are rarely based on what's safe for any given stretch of road, most of the time it's an arbitrary limit that might be safe on one road but might be 20-30MPH slower than safe on another.

Human nature shows that most people drive at the speed that they feel is safe, referencing the speed limit only so far as the potential to get a speeding ticket. If I-15 between L.A. and Vegas was guaranteed to be free of speed enforcement you'd see average speeds close to 100MPH on that road (most of it is posted at 70 with some sections at 75). Of course you'd also see more accidents because you have the wildcard of a tiny number of people driving 130-140 weaving in and out of traffic.

I don't understand why people think driving at 100mph is perfectly safe. Its not. Physics are a *****.

Here's a super safe Volvo-

 

[dbostrom]

Physics are a *****.

Indeed. KE=1/2mv2

Speedometers might do better to read in units of how many ounces of water could be boiled using current kinetic energy of the vehicle. The current presentation is actually critically deceptive in terms of the important information contained in the number.

And, why it's good not to speed where you cannot guarantee you'll not hit a pedestrian. "Oh, I'm only going 5 over 25." Big difference.

 

[Packard V8]

I don't understand why people think driving at 100mph is perfectly safe. Its not. Physics are a *****. Here's a super safe Volvo-

Yabbut being in or near moving vehicles is inherently unsafe. The photo isn't readily available, but I just saw three cars damaged that badly, all hit by a truck while they were sitting at a traffic light. There are 40,000 traffic deaths a year and most happen under 60 MPH.

Yes, physics is a ***** when 80,000# trucks are on the move. Self-driving trucks will be the first on the road. A computer on it's worst day is infinitely safer than the average trucker on an average day.

jack vines

 

[dbostrom]

Self-driving trucks will be the first on the road. A computer on it's worst day is infinitely safer than the average trucker on an average day.

It's interesting that in the general aviation world of rich dentists etc. aircraft have for some time been capable of handling nearly all phases of flight by themselves, technically speaking (and with the addition of some interconnects), but even while the problem of safe aircraft navigation is vastly simpler than that of an automobile we don't see any movement toward mandated operational exploitation of automation potential in GA. Rich dentists etc. continue to spread themselves, their aircraft and whomever is unlucky enough to accompany chronically rusty pilots all over the landscape, by managing to fly into terrain while having perfect information as to their whereabouts literally straight in front of their faces.

And that's in a market entirely accustomed to regulation that is extraordinarily rigid compared to the automotive world.

We like doing things the hard way. I'm not at all confident that motivated reasoning over anecdotes with no statistical significance won't result in permanent freedumb of operation of our vehicles.

 

[PhilR]

I don't understand why people think driving at 100mph is perfectly safe. Its not. Physics are a *****.

Here's a super safe Volvo-...

While I empathize with the people involved in that pic, my sick brain reminds me of an editorial I read in a car magazine years ago. The author was trying to understand why Volvo drivers were always driving so slowly. His theory: Do suppose people purchase Volvos because they feel they NEED to be driving the "safest" car???

Full disclosure: my wife drives a Volvo C30 coupe and, although it's a sporty little car, she surely does not drive it that way!

 

[dbostrom]

I dunno. On longish (190 mile) round trips w/close to nameplate weight in the car, 4% would give back about a third or maybe even half of the range loss I've observed w/that scenario, those trips being 90% 60-74mph. Another way of looking at it.

Hubcaps don't do much for the gap between the tire and the body, and a **** of a lot of air is being accelerated there, with hideous pressure drop/rise meaning equally horrible separation and turbulence.

I suppose windage in the wheel structure would be another thing to think about, at higher speeds. But that would come into play (yet again) at relatively high speeds, considering that Bolt wheels are spinning at about 1,400 rpm at 100MPH. In electric motors (where windage very much is a thing) rotational drag (windage) is considered to become a notable factor at maybe 1,000 rpm (significant if motor power is low or ultimate efficiency is at a premium).

There are some ancient papers describing empirical measurements of windage on automotive wheels but these days a lot of the research seems concentrated on the bulk contribution of wheels and wheelhouses as opposed to windage.

Some numbers and theory:

Investigation of Simple Possibilities for Reduction of Drag due to the Wheels of Road Vehicles

Aerodynamics Around Wheels and Wheelhouses

The Aerodynamic Influence of Rim Design on a Sports Car and its Interaction with the Wing and Diffuser Flow

(the latter two are particularly nice master thesis work and as such automatically useful literature reviews in themselves.

 

[ai4px]

Where's around here? Are these actual local laws, or just perceptions of local customs, or behavior?

“Here” is the middle of South Carolina. In the words of Foghorn Leghorn... It’s a joke boy... a jooookkkkkeeee.....

 

[DaV8or]

Aerodynamics Around Wheels and Wheelhouses

Sounds like people wanting to reduce drag and increase range, should be thinking about designing rear fender skirts in addition to the aero covers.

 

[Packard V8]

Sounds like people wanting to reduce drag and increase range, should be thinking about designing rear fender skirts in addition to the aero covers.

What goes around comes around. Everything old is new again.

jack vines

 

[GregBrew]

What goes around comes around. Everything old is new again.

jack vines

Ahhhh...memories! Heck of a car.

 

[Packard V8]

Ahhhh...memories! Heck of a car.

If only we could buy one today with the Bolt drivetrain.

jack vines

 

[DaV8or]

What goes around comes around. Everything old is new again.

jack vines

That's what's funny. Those thesis papers written fairly recently linked above, went to great lengths to prove what GM had already proven back in the '90s. Funny what you can find out with engineers and an actual wind tunnel. :laugh:

 

[DaV8or]

If only we could buy one today with the Bolt drivetrain.

jack vines

I guess for some. For me that car was almost useless back when it was new and it's almost useless to me now with the Bolt platform. If it were available with the Bolt platform I certainly would not be buying it unless it were ridiculously inexpensive.

 

[Packard V8]

I guess for some. For me that car was almost useless back when it was new and it's almost useless to me now with the Bolt platform. If it were available with the Bolt platform I certainly would not be buying it unless it were ridiculously inexpensive.

Define "almost useless" ?

jack vines

 

[redpoint5]

If you are caught going 25mph over the posted speed limit in Switzerland, they arrest you, suspend your license and then fine you based on your tax return and personal wealth.

Seems like more motivation to not pull over for the cops. While I don't drive more than 10% over the limit when around others, I certainly go 25+ over on the motorcycle on backcountry roads.

I'm all for reasonable enforcement of reasonable laws. A fine adjusted to income is a great method of applying disincentive evenly to the population. A year in prison isn't good for the individual or society though.

Of course I've been on roads in the U.S. where driving 65 even in the right lane was dangerous. Granted it's not common because trucks usually bring the right lane down to 55-60 but on a smaller highway without much truck traffic the flow of traffic could be 80 in the left lane and 75 in the right.

Actually the last time I drove down the 5 from Northern California I was driving a large step van (basically a UPS truck minus the brown), I was doing 70 in the right lane which was flat out for this van and was getting passed by semi trucks (not all of them obviously).

In my youth I did 85 down the Grapevine and was passed on the right like I was standing still by a double-trailer. He must have been doing 100 MPH. His brakes weren't burning, so I assume he just wanted to go fast.

It's a shame that there's really no way to get the kind of numerical data that would be useful in edge cases like this, without aggregating data from say 100 owners with the exact same treatment over a long period of time. Anything short is anecdote because of variability in the environment experienced by individual vehicles.

A coast down test is pretty darn reliable at testing aerodynamic treatments. You take a flat section of road and accelerate up to a given speed. At a marked spot on the road you go to neutral and allow the vehicle to coast until it drops to a predetermined speed, and you time how long it takes. Several runs must be done in both directions. Improvements in aerodynamics will increase the amount of time it takes to coast down to that speed. Testing should be A-B-A at minimum (stock measurements, aerodynamic measurements, stock measurements) to minimize the chance that other variables are at play such as warming tires, warmer air temperature, or changing wind speed. If the average of all A tests are close, that gives a high degree of confidence that B tests were performed under similar enough conditions to draw conclusions.

You can roughly calculate the improvement in aerodynamics based on this info if you already know the vehicle weight, frontal area, and starting coefficient of drag (which we should be able to obtain). Since the weight and frontal area aren't being modified, all improvements are in the coefficient of drag (the efficiency of the shape).

 

[DaV8or]

Define "almost useless" ?

jack vines

Well, it's a car and in some circumstances when I'm by myself, or possibly one other person, don't need to drive a long distance and don't want to carry anything, I could use this car. It would still be of use. Since I carry stuff a lot, sometimes even use my back seat and I don't have loads of money to spend on specialized equipment, the car is mostly useless to me and I wouldn't buy it.

Having said that, I like fast two seat convertibles that are mostly useless to me as well and I keep one of those for fun because I like cars. So if someone wants to buy an EV-1 2.0, more power to them! Have at it. I just would never buy one. I also forgot to mention that looks are important to me as well. I like my two seat convertibles to be sexy looking too. I find little sexy, or attractive about the EV-1. It is pure function and little form.

 

[beeguz]

The spun aluminum hubcaps were the rage when I was in my early teens, back in the late 50's.


I should have kept the spun aluminum caps I got when I bought my older brothers 48 chevy.

 

[raitchison]

Sounds like people wanting to reduce drag and increase range, should be thinking about designing rear fender skirts in addition to the aero covers.

I am no aerodynamics expert but I have an interest in it. I do think there's some (relatively) easy gains to be found in the Bolt as far as aerodynamics improvements, whether there would be enough benefit to justify the cost for anyone who doesn't spend a lot of time at highway speeds (or even for them) is another question.

Personally I'm keen to lower my car by ~1", I suspect that this will provide some aerodynamic benefit for relatively low cost (should be under $350 once lowering springs are released for our cars).

I think that aero hub caps can help but to really improve your wheels aero properties you'd likely need to replace your wheels. The cost of this would be very high and probably not worth it.

Likewise with under-car aero kits or side skirts, again significant gains will come at a cost that most won't be willing to pay.

Really we're limited by the shape of the car, it's too tall and not long enough. If it were 2" shorter (height wise) and 6" longer it would likely provide more favorable aerodynamics than everything we're talking about combined. But then GM couldn't sell it as a "crossover" it would be *gasp* a wagon.

 

[Packard V8]

Well, it's a car and in some circumstances when I'm by myself, or possibly one other person, don't need to drive a long distance and don't want to carry anything, I could use this car. It would still be of use. Since I carry stuff a lot, sometimes even use my back seat and I don't have loads of money to spend on specialized equipment, the car is mostly useless to me and I wouldn't buy it.

Having said that, I like fast two seat convertibles that are mostly useless to me as well and I keep one of those for fun because I like cars. So if someone wants to buy an EV-1 2.0, more power to them! Have at it. I just would never buy one. I also forgot to mention that looks are important to me as well. I like my two seat convertibles to be sexy looking too. I find little sexy, or attractive about the EV-1. It is pure function and little form.

That's as interesting a circular argument as I've ever seen presented here.

Agree, aesthetics are not absolute, but an individual perception. I've owned many two-seat convertibles and coupes and do find the EV1 attractive. It's the ultimate expression of "form follows function." It would be hoped the version 2.0 with Bolt drivetrain would have a different style face.

FWIW, when we were in the Chevrolet dealer showroom buying our Bolt, there were seven Corvettes in and around the immediate area, from $55,000 to $115,000. I calculated we could probably get a deal on the base model Corvette for very little more than the sticker price of the Bolt, on which there were no deals to be had.

Of course, then the income tax and sales tax deductions changed the equation by $10,000, so no longer apples to apples. However, fantastic car for the money the base Corvettes are, a Corvette just no longer does anything we need done. I wouldn't trade the Bolt straight across for the 'Vette if I had to use it for everyday errand running.

Your opinions and results may differ.

jack vines