Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 



Forgot your password?
typodupeerror
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 Internet speed test! ×

Comment Re:The problem (Score 1) 143

Quads can't, no variable pitch blades.

And you don't see the solution to that?

It's really simple. Regulators mandate safety standards so that - in real world conditions - you don't have cars constantly falling out of the sky due to failures or running into buildings. Engineers determine the designs to meet those standards. If they can't, they don't get to sell it.

Comment Moving the congestion around- not new congestion (Score 5, Insightful) 131

When retail stores were in downtown areas, there was tremendous congestion when people went to shop.

When they moved around to different malls, there was still a lot of congestion around the strip centers and malls (as recently as the 90s, I remember waiting thru 15-20 minutes of traffic to get into the parking lot.

Now, I bought and paid for 5 products on amazon- I didn't drive- I didn't consume gas- I didn't contribute to congestion on the roads- I didn't get into a car accident, and my car wasn't damaged in the parking lot.

Say 20 consumers shopping personally consume 400 minutes of road time-- 20 shoppers delivery shopping consume 40 minutes of road time.

The problem is the parking infrastructure will need to adapt.

There was a time when we had a mail box at every house. Now, a lot of places have 1 mail box.

Perhaps we'll end up with a big centralized delivery hub for each block. Perhaps a designated parking area for delivery vehicles.

Amazon is looking into drones.

In any case, it's not a problem in my neighborhood yet. They pull up, drop off stuff. The road is constricted but not blockded at any time. Then they leave within 2-3 minutes. This may be more of a problem for high rise condos or apartment buildings than residential neighborhoods.
 

Comment What computer? (Score 1) 106

When I got to college I was able to sneak into a lab and use an ASR33 teletype on the Telex network to remotely log on to Dartmouth to use BASIC.

At my own school it was cards in a window, come back later for the printed output. And you'd better have an account that paid for it.

Didn't really get to 'cut my hacker teeth' until my sophomore year, when some oddball ins-and-outs of contract financing left me with a student job where I had, a couple times a day, the remainder of a one-hour time slot with my work on the machine done, blocked waiting for the other department to do my output's tape-to-print, and a mainframe computer all to my self, on which I could do what I wanted while waiting for the results of the real work (or compile attempt) to be printed.

(What I did with it was talk the hardware tech into getting the paper tape I/O working, then bootstrap up a card-image editor, from scratch, on paper tape, to where it could emulate the Dartmouth BASIC environment - with Fortan on card-deck images in RAM or on a tape library - including the RUN command; Once that was working I'd get one compile/debug turnaround per three-to-five minutes, for a couple hours rather than two per day. This ended up with the lab management impressed and me reassigned to be in charge of the OS, library, and doing much of the lab's software.)

Comment Re:I agree, but not for the same reasons as Musk (Score 1) 143

Congratulations, you have it entirely backwards.

The maximum efficiency of a prop, in newtons per watt, is 1 / (v_wake + v_freestream), where velocity is in meters per second. The faster you're moving (the freestream velocity), the less thrust you get per watt. Which is why large props are more efficient (more air moved at a lower wake speed), particularly at low speeds, and same for high bypass jet engines.

Now, in terms of "energy per 100km" or "miles per unit energy", obviously a hover yields "infinite joules per 100km" and "0 miles per joule", because you're not going anywhere. But that's an entirely different situation than propulsive efficiency. If you want to start factoring in motion, then your cross section / drag coefficient / L:D ratio / altitude (and thus density) and so forth come into play, and the optimum speed comes down to a balance between a wide range of factors - the faster you go, the less time you spend flying, but your drag increases quadratically, and your prop efficiency drops (the rate of drop relative to the difference between the freestream and wake velocities). Airplanes maximize this balancing point by having extremely low drag coefficients (Cd), far less than cars tend to have.

Comment Re:Really? (Score 1) 143

The assumption is that if flying cars were common, there would be vastly more locations. As they basically function like helicopters (in most conceptions - VTOL), they need only something equivalent to a helipad, not an airport. Which is much cheaper and smaller footprint than an airport.

To get to the point of allowing takeoff and landing from, say, a driveway, you'd have to have a long track record of excellent proven safety, and levels of noise reduction that current technology doesn't yet support. It's certainly conceivable in the future, but is anything but a first step for companies working on flying cars today.

I personally view flying cars as pretty much inevitable (although not around the corner) regardless of whether or not they're pursued directly at present. Namely because of delivery drones. Businesses are not going to stop pushing for them because there's such an economic case for them (not having to drive a big truck around city streets, pairing trucks with drones to not have to go down each sidestreet or stop at each location, etc), and they'll advance the technology as needed to get approval - starting small. But economics will continually push them toward making larger and larger models, and the technology to get approval for those. And eventually you'll have models large enough to carry people around, wherein the question will inherently arise, "Why, exactly, aren't they carrying people?"

Comment Re:Really? (Score 1) 143

So your concept is that something statistically likely to crash and injure people would be approved by regulators, rather than manufacturers being forced to prove reliability in real-world usage conditions before being granted approval?

Comment Re:Really? (Score 1) 143

The assumptions involved in your post:

1) Flying cars would be allowed to just take off and land wherever they want.
2) People would be manually piloting them.

I don't know where you're getting your concept of flying cars, but none of the flying car advocates I've ever heard from advocate for either of those things.

Comment Re:The problem with flying cars is... (Score 2) 143

I don't want to think of what they would be like as pilots

Yes, because when people talk about flying cars, they totally mean manual piloting.

I don't even want to consider those traffic jams.

Um...

Waterfall Sr.: Our peace ring has 'em trapped like a tiger in a washing machine!
[The engine of the Planet Express ship flares up.]
Leela: Get ready!
Protestor #1: Look out!
Protestor #2: Hold on!
Waterfall Sr.: Here they come!
[The ship rises up from the middle of the peace ring and tows the tanker over the top of the protestors. It flies away.]
Leela: When you were planning this peace ring, didn't you realise spaceships can move in three dimensions?
Waterfall Sr.: No, I did not.

Slashdot Top Deals

"They that can give up essential liberty to obtain a little temporary saftey deserve neither liberty not saftey." -- Benjamin Franklin, 1759

Working...