Wing mirrors on cars

[rbowman]

I could totally do that.

[NY]

Interesting how different English-speaking countries devise different terms for the same thing. In the UK, it's called "surface dressing". And it's a

*terrible* way of surfacing a road. To my way of thinking, if they have to put up signs after they've resurfaced a road, saying "SLOW - 20 mph - Loose Chippings" it means that they haven't done the job properly: either they should roll the chippings into the layer of tar that they've sprayed on the road, or else they should go along with a massive Hoover and suck up any loose chippings that have escaped being rolled into the tar. Relying on cars to roll in the stones is very hit-and-miss, and leaves loose chippings which are a skid hazard.

Much better is to pre-mix the tar and the stones, and to tip this this sticky substance onto the road and then roll it flat. That lasts a lot longer (*) and doesn't go "bald" as the stones of surface dressing / chipseal gradually wear off and leave bare tar in areas of heavy usage (eg on corners).

(*) Always assuming that it doesn't crack and let water in that the freezes in winter.

[sam]

Approximately .000861% of car windshields are damaged by fresh chip-n-seal.

[rbowman]

Proving once again that no matter what you call a bad idea it ermains a bad idea. Since the projects occur in the summer months when I'm usually riding a bike rather than driving the car I really detest the process. Luckily one of my bikes is a street-legal enduro so I can treat it as another off-road segment.

Rain is another problem. The surface compacts under the travel path of the tires so they become two water filled ditches.

[James Wilkinson Sword]

the dishwasher perhaps, but the microwave would burn the tracks.

[James Wilkinson Sword]

There is no way anyone would have that data. Most won't report it.

[James Wilkinson Sword]

I assume it's a very cheap way of doing it. Not sure why around here it's done on 10% of resurfaced roads, and none of the others. It doesn't seem to follow any pattern of how heavily the road is used either.

[Vir Campestris]

They changed the rules. Not pleasure boats IIRC, but commercial is OK. But I won't swear to that.

Andy

[Vir Campestris]

Let's try this slowly.

You're cruising down the freeway, engine not working very hard. As it's a piston engine it's sucking in a volume of air (restricted by the throttle butterfly, if it's not diesel) heating it then letting it expand. When the piston reaches bottom there's still a fairly high pressure in the cylinder, and you let all that heat and pressure go to waste out of the exhaust.

Or you could stick a turbocharger in the way, which will increase back pressure slightly and put a higher pressure up against that butterfly for no good use.

OR you could put a turbo generator in the exhaust. That'll raise the back pressure slightly, but generate a LOT of electricity. tens of kW. A significant proportion of the engine output at cruise. And which with the right powertrain you can do something useful with.

There's a reason why turbochargers are more efficient than superchargers, and it's because they recover energy from the exhaust that would otherwise be lost. This has been known since WW2, when turbosuperchargers (sic) were first fitted to aircraft.

Andy

[Vir Campestris]

Google "berlin beer bike". No quotes.

Andy

[TMS320]

"Heat recovery" in formula 1

It was turbo compound. The exhaust turbine was connected to the crank not a compressor.

[rbowman]

Cheap in the short term. They do it in the city but it seems like they're redoing it every five or ten years. Last summer they laid real pavement almost all the way to my house. That's after 30 years of doing nothing but ineffective pothole repair so maybe they felt they'd saved enough money to do it right.

You're right though. It's a lightly used road that in fact turns to dirt about about a quarter mile down. I'm not complaining though even if the huge potholes used to let me practice my hazard avoidance skills on the bike.

[rbowman]

Another good idea stolen from the Germans :) Of course, the largest ancestry group in this state is Germans so maybe it was just a parallel development. The Irish are the second largest group and they know a thing or two about beer also. St. Patrick's Day in Butte is something to be remembered -- or not remembered depending on how much you get into it.

[Vir Campestris]

How sure are you of that?

This 1943 pamphlet

thinks one of the great things about a turbo is better flexibility. But they aren't linked to the crank. I've never seen such a thing, and I've looked at enough aircraft to bore you.

Andy

[boltar]

10s of Kw? Maybe if its some massive tuned V8, otherwise fat chance.

Not this myth again. They don't "recover" any energy from the exhaust, what they do is use it to compress incoming air. That compression in itself does nothing, its only when combined with more fuel you get the extra energy which comes entirely from the fuel.

Put your hand over the end of the exhaust pipe of a running engine. You think thats a lot of energy? Its little more pressure than your average hairdryer

[The Natural Philosopher]

A high performance turbo can pull a fair bit from the exhaust. IIRC thats one of the energy recovery systems in this years F1 engines.

But you are essntially correct: the aim of a turbo charger is primarily to get more air into an engine without having to go mad on valve sizes.

Theor use in aircraft was primarly to maintain performance at altitude, not a ground level power increase per se.

And turbo lag is not an issue on aircraft engines really.

[boltar]

Sure, but those engines are some way removed from your average 1.6 :) No doubt at max rpm your average car engine is sending multiple horse powers out the pipe as pressure and heat, but thats when you need the turbo the least. Its down low where not much is happening exhaust wise that they're most useful and its taken car manufacturers years to get them to work well at low rpm.

Indeed.

[TMS320]

It isn't a myth.

The development for aircraft was turbo*compound*, not *charger*. Probably similar to the principles of double or triple expansion steam engines.

"generating 20 percent additional take-off power without increasing fuel consumption."

[TMS320]

If 1943, probably got nowhere because they quickly developed it to make the reciprocating bits redundant.

It wouldn't bore me.

[boltar]

It is. None of the energy the turbo gets from the exhaust directly gives the engine any more power. Any extra shove the pressured air gives to the pistons on the intake offset by the pistons on the compression having to work harder to compress the greater volume of air. As I said , the extra energy due to turbo charging comes entirely from the fuel.

They're not turbo chargers so irrelevant.