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Comment Re:We've been over this (Score 4, Informative) 55

The issues with electric planes have been beat to death here

Where? Slashdot? I can't recall ever reading about electric flight beyond drones, though I'm sure there has to have been some in the past.

What issues?

The main problems are batteries, not electric propulsion itself. That batteries are far heavier that fuel on a lbs/kw basis, plus you don't get the bonus of the plane getting lighter the longer it flies. And high bypass turbines on planes aren't as inefficient in use as the ICE in cars (and planes are much more weight sensitive than cars) so you can't trade weight and drivetrain efficiency for useful range like you can in electric cars.

Also, for commercial planes they spend very little time on the ground between flights; so you don't have time to recharge batteries. So you're looking at a battery swap technology as well to keep the turnaround time comparable to refueling.

That said, if the distributed electric propulsion is as efficient as NASA thinks it might still be a net win even if you have to pair up the electric motor and prop placement of this X-57 with an onboard electric generator. In which case all the downsides of batteries are irrelevant. (Then you could look into whether a hybrid design with a some batteries and a smaller generator made sense)

Comment Re:Question for you... (Score 1) 149

I'm not a petroleum engineer, but I'm familiar with the industry and I can find no process known for manufacturing petroleum products from raw materials. You can find processes for converting one form of fossil fuel from another (ie petrol from coal) or for extracting petroleum from tar sands. None of these processes actually create petroleum from raw materials.

I guess it depends on how you define "raw materials" but my understanding is that the old Fischer Tropsch process can produce petroleum products from carbon monoxide and hydrogen. This was invented in the '20s and was used by the Germans in WWII to produce something like 1/4 of their automobile fuels.

Now admittedly for economic reasons the raw materials tend to be derived from coal and/or natural gas; the later often in places where it's not economical to distributed that gas directly into the marketplace. But there's nothing, AFAIK, in the chemistry to prevent you from using other raw sources - they'd just take more energy to process and generate the petroleum.
Of course there is a net energy loss in this process, but it would let you use fixed power generated by other sources, plus raw feedstocks, to generate synthetic petroleum for mobile applications. However there's little economic point at this time given that it costs more than even shale oil.

Comment Re:User error (Score 1) 567

Locking Torque converters have been the rule for a LONG time, like since the 70's... With all due respect for the guys from Car Talk, this *helps* with the efficiency, but there still is some energy losses due to the necessity of running the automatic part of the transmission. You have to keep the shift clutches engaged, that takes hydraulic pressure which implies a pump is running someplace. You also must circulate the transmission fluid to keep the various things lubricated and cool, which takes some power too. Power consumption in the transmission means less power for driving getting to the wheels.

I'm not saying the differential between the automatic and the manual is all that much these days, it's not, but if you are on the highway the manual is going to be better. Now if you want to argue that it's unlikely that your average skilled driver would be able to achieve better gas mileage in a mixed environment of city and highway driving on their manual, that for 99.9% of drivers would do better on an automatic, I can only agree with you. However, just straight out driving down the road at highway speed, not shifting, that manual is going to be hard to beat, all things being equal.

Of course things are rarely equal. For example (outside of big rig trucks) manual transmissions seem to top out at 6 gears, while most automatics are now at least 7 with some having 8, or even 9 gears. (A far cry from the old 3 speed automatics).

That gives a better chance that the automatic can select a more ideal gear ratio for your speed than the manual. Potentially having the engine at a better RPM could more than offset the parasitic losses of the automatic transmission.

Comment Re:The technical problems with this are immense. (Score 1) 346

Here's the real answer:

A typical gas-powered sedan's fuel tank may hold around 15 U.S. gallons of gasoline, which weighs about 40 kg. The tank itself may add another 10 or 20 kg, for a total of ~55 kg. In contrast, the battery pack of the Tesla model S weighs 540 kg! - even though its range is still a bit less.

This 10x weight increase is acceptable in a sedan, because the gas-powered sedan already weighed about 1400 kg; adding another ~500 kg is significant, but not overwhelming.

Also the electric motors and associated fixed gearboxes probably weight significantly less than the ICE engine, transmission, and associated hardware. So the net weight increase for switching to electric propulsion is probably noticably less than the 10x increase you ballparked.

Comment Re:Obama, Champion of the Firearms Industry (Score 1) 555

If criminals didn't frequently obtain their firearms by stealing them from legitimate users I might buy your argument a little more.

A smartgun should be able to prevent a criminal from immediately using a stolen gun; in other words they can grab it away from you and then shoot you with it.

But bullets and guns are ultimately too simple of devices to keep people from being able to strip off the "smarts" and render a stolen smart gun usable again. Ultimately all the smarts are doing is deciding whether or not the firing pin get to strike the primer in the base of the bullet. It seems there's only a couple ways the smarts can control that; one is to disrupt the mechanical linkage between the trigger, the firing pin, and the bullet and the other is to replace that with an electronic path where you use a servo or something activate the firing pin.
The first type you remove the ability to disrupt the mechanical path and the second type you replace the smart electronics with a simple connection from the trigger switch to the electronic firing pin activator.

Smart guns, if they have sufficiently lower failure rates solve a number of problems; but criminal stealing a gun and making it usable for a later crime really isn't one of them.

Comment Re: Smartphones have problems too (Score 1) 417

This is not true. Assisted GPS doesn't rely on cell networks, it makes use of cell networks for faster fixes. They still work fine without service, but they do take much longer to get a fix. This is evidenced by the fact that you can put your phone in airplane mode and hold it near the window of an airliner and still get a 10-satellite fix.

Now, that said, you may be able to have maps downloaded for offline use, but in Google Maps searching and route-finding still require a data connection, limiting its usefulness.

Some people may have been confused on this point because Apple, up until iOS 8.3 (released less than 5 months ago), would also turn off iPhone GPS receivers when you put them into airplane mode.

Comment Re: Most unlikely technology in 1981: Handheld GPS (Score 1) 276

always thought the most unlikely technological development in my lifetime was the handheld GPS device. It would be "most unlikely" because it required tremendous, simultaneous, and largely unforeseen advances in several different technologies, each of which was hard to predict in 1981. The list is at least:

1. Low power, low voltage, low noise L-band receivers, sensitive enough to be compatible with the weak signal coming from the internal antenna of a handheld device;
2. Stupendous amounts of digital signal processing, also at low power and low voltage;
3. Digital map databases of (substantially) every road in the world, accurate to a few meters;
4. A substantially world-wide, wideband wireless data link to get the digital map into the handheld device in the first place;
5. Low power, low voltage, high resolution, multicolor flat panel displays;
6. Gigabytes of low power, low voltage data storage memory; and
7. High energy density, high power density batteries capable of supplying the whole thing.

And, perhaps most impressive of all, the manufacturing technology to make all of the above small enough to fit in a handheld device, at a price low enough to sell by the zillions.

Of the list above, probably only #2 could have been predicted, and then only if one were willing to extrapolate the then-relatively-new Moore's Law by a very large amount. (Recall that Mead and Conway had only written their Introduction to VLSI systems the previous year; until then it was not clear that such complex chips could even be designed on human time scales, let alone built for a profit.)

The fact that a handheld GPS device is now an anachronism, since the technology is now small enough and low-power enough to be integrated into other handheld devices, like smart phones, pleases me no end.

Add to that list an item 0:
That a satellite cluster deigned, paid for, and deployed for military use would be freely available for civilian use. (President Regan's decision to allow that, in the wake of the Korean Air flight 007 wasn't made until 1983 and the satellites weren't launched until 1989).

Without the military necessity and funding behind it there's basically no chance that the GPS satellites would have been deployed, and without Regan's decision there's no reason they would necessarily have supported unencrypted civilian use.

But yeah, I like your unlikely technology prediction. Although certainly much less capable handheld GPS units existed long before the map based raod navigation one's you were primarily referring to.

Comment Re:Germany lost the BoB because of Hitler's stupid (Score 1) 353

it would still have the option of training new pilots in Canada

Which they were already doing (Which you probably knew or you wouldn't have mentioned it.)

Yes. I should have used "ability to train", or "ability to continue to train", instead of "option of training".

I did know they did flight training in Canada, and didn't mean to imply otherwise.

Comment Re:Germany lost the BoB because of Hitler's stupid (Score 2) 353

The Germans lost the battle for many reasons. They were losing aircraft fast, not just in combat but due to maintenance needed. Planes have to be pulled out of the line and refurbished every so often. They can't fight forever. Unknown to the Germans, the British were far out producing them in fighter aircraft. Almost double the production. The problem the British faced was a lack of pilots to man those aircraft, and a degradation of the support infrastructure. Same as pilots, the ground crew, maintenance and airfield engineers were wearing out. But, so were the German ones. It turned into a battle of attrition. The Germans were deeper to begin with, but the British were losing less over time. The Germans eventually broke first. Their change in tactics was to cover the wearing out of their air force.

And don't forget the limited range of the German fighters.

The Battle of Britain was more the battle for southeast Britain. Unless RAF Fighter Command cooperated, by staying in a losing fight, there was basically no way for the Luftwaffe to seize and maintain air superiority in support of a seaborne invasion.

The RAF had plenty of bases north or west of the Luftwaffe fighter's effective range; so if the attrition started going too badly against the RAF they had the option of temporarily pulling back to train up additional units, but could still surge forward if / when the invasion began. And Luftwaffe bombers would get shredded trying daylight unescorted raids against those more distant airbases.

Ultimately, as painful as it might have been to people on the ground in that southwest portion of Britain, the Luftwaffe could only inflict a level of attrition that the RAF was willing to accept. It would be quite different if the Luftwaffe had the range to put fighters over any part of the UK, because then the RAF has to come up and fight, or its units get destroyed on the ground by fighter sweeps or escorted tactical bombing missions; though at least it would still have the option of training new pilots in Canada - so it wouldn't be quite as bad off as the Luftwaffe was by the end of the war where there was a good chance a trainee pilot would be shot down by Allied fighters before finishing flight training.

Comment Re:Wake up SAE. Standardize TREs now. (Score 2) 191

I like the idea of towable range extenders, but if you're renting one, what are the advantages over automated battery swapping instead?

I can see a couple advantages to towable range extenders.

Probably the biggest one is that once you've rented it you can continue to extend the range indefinitely by utilizing existing widely deployed infrastructure (stopping at a gas station to top up the generator's tank). So you can use to for trips into areas where the charging or battery swap stations haven't reached yet.

It also sidesteps the issue or concern about people swapping out, or receiving, an old reduced effective capacity battery pack at a swap station.

And the rental place needs less infrastructure than a battery swap place. To do battery swap you need the tools (or automated machines) and access to pull the existing pack and install a new one. For a towable rental you barely need more than an empty lot to park them until they've been rented.

And when a battery swap place gets a battery back they need a pretty hefty electrical connection to charge it back up for the next use. The towable rental place needs a gas can (or to take the returned genset by a gas station to top it up); plus they could use the rental car style gas fees to encourage people to return the range extender with a full tank - no practical way to do the same for battery swap.

Comment Re:The fog of time (Score 1) 160

You could just wander into the stars, get lost, run out of gas, or fall afoul of an enemy you weren't prepared to defeat, lose the game and have to find a 20-gameplay-hour-old savegame to usefully recover.

You could certainly get taken out by an enemy you couldn't defeat; wander into Ur-Quan space with too slow a main ship, or those damned slylandro probes. (Doesn't do much good to emergency escape if you can't run clear in hyper)

But short of providing a fight with the traders, or in the very near end game (after they fled), it was virtually impossible to permanently run out of gas. The traders always come alone eventually and give you more. I once got bored and pushed it and I think I ran out my ship out of fuel five or six times in a row and they kept showing up like AAA (even if you have no resources or info to trade them you still get gas to get back to Earth)

Comment Re:Japanese Military (Score 1) 282

The new USS America [] has a flight deck of the same size. France's (only) aircraft carrier is about ten meters longer. The gigantic Nimitz-class supercarriers are the exception to the rule.

Just using flight deck length is misleading.
While the French Charles de Gaulle carrier is only 13 meters longer, it's almost 70% wider and and overall it's twice as big (displacement).

Here's a bit more detailed listing,
name (year launched)
tonnage (standard), length x beam (flight deck)

Izumo (2013)
19,500 tons, 248 x 38 m

HMS Invincible (1980)
22,000 tons, 209 x 36 m

HMS Ark Royal (1955)
36,800 tons, 245 x 52 m

Charles de Gaulle (2001)
37,085 tons, 245 x 52 m

USS America (2012)
45,000 tons, 257 x 32 m

USS Midway (1945)
45,000 tons, 295 x 34 m

HMS Queen Elizabeth (2016, planned)
70,6000 tons, 284 x 70 m

USS Nimitz (1975)
100,000 tons, 332 x 77 m

The Izumo is less than half the displacement of a late-war WWII design, and lacks the flight deck area of more modern carriers (which due to their angled flight deck are substantially wider at the flight deck than at the waterline). Unsurprisingly it's closest to the displacement to the Royal Navy's old through-deck cruisers (aka 'Harrier carriers') which had the similar mission of supporting helicopters for anti-submarine patrol.

Comment Re:Valet Key (Score 1) 453

Does the valet key somehow negate the manual trunk release? Honest question, as I own a hatchback.

Not automatically, but (most?) cars have a disable switch you can throw to disconnect the trunk release button/lever. It's always behind a lockable area that the valet key can't open - I've seen them in the trunk itself (often a lever on the side of the lock mechanism) or in the glove compartment.

Hit that disconnect, lock the trunk and glove compartment with the normal key and then the valet key won't be able to access the trunk. (My old car you also had to lock the folding rear seats with the normal key; those weren't linked to the trunk release button, so it was more of a pain)

Comment Re:Harrier? (Score 1) 86

een done. S-72 and X-50 prototypes. Its very unstable. The bring a rotor to a controlled stop thing is easy, existing rotor brakes can be geared to align it fairly precisely when it comes to a stop. The lift transition is the issue. It's not just that lift is basically 0. It's that one half of the rotor disc (the theoretical abstract describing the lift forces) has to completely reverse the airflow of the lifting surface.

Its essentially an expanded case of the Retreating Blade Stall problem.

But the retreating half of the rotor disc has to, as some point, go from generating lift from a retreating motion through the air (moving backwards relative to airframe, due to rotation) to generating lift from an advancing motion through the air (moving forwards, relative to airframem though no longer rotating). The easiest way to think about it isnt to think of it as going from rotating to fixed, but rather think about a rotor that is simply being reversed in direction (simplfies a lot of math).

So at some point in the middle there, half the rotor disc will fall below stall speed, and experience a stall similar to the effect of a Retreating Blade Stall. Worse, won't regain sufficient lift until its now going ~100 KIAS in the opposite direction. Think of it as stalling between -100 and +100 KIAS (example number) as it crosses the transition.

The only craft I can see being able to cross that boundary zone would be a very small, very lightweight rotor that is able to make extremely fast accelerations, and thus cross the zone before it's able to affect the craft much. A full scale craft would simply have too much inertia/momentum to be able to make the transition fast enough, without tearing itself to pieces. Likewise for any craft trying to stop the rotor and use forward motion to generate the lift.

Theoretically couldn't it work if the craft had enough sufficient fixed wings to provide most of the lift necessary for level flight at transition speed?

Then you should be able to trim the rotor disk to near zero lift (beginning a relatively mild decent) before braking it to a stop. Once stopped, retrim it for forward lift and level off.

Mind you those big wings would likely do ugly thing to the airflow in vertical lift mode...

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