184 posts • joined 28 Apr 2008
Delta-V is a bitch too.
Re: What happens?...
Up at the launch altitude, I would think any control surface deflection would have little to no impact until the craft reaches quite a high velocity. In fact, I wonder if you'll have any real control authority until it descends a fair way.
USian lawyers obviously don't take that to heart. Even a cursory analysis by a competent engineer would have told them to lay it down carefully & walk away quickly. But then when have the hot-to-invest types listened to anyone?
For us formerly teenage pyromaniacs, this is a classic text on how it *should* be done...
Not really true. The annuity can fail to be paid if the provider goes bust, as can a pension - many company pension schemes are under-funded because they took pension contribution holidays inadvisedly in the past. Similarly government could elect not to continue to pay benefits/pension etc. The issue here in judging the value of a future stream of income is the risk that it will stop or vary at some future point. You could argue that an annuity has less risk of stopping than a state benefit, but I could equally argue the opposite, based on market conditions, political commitments and a whole raft of other factors. That makes valuing the benefit income stream as an asset somewhat more problematical, but it doesn't completely destroy its value.
Re: The ultimate question of life the universe and everything.
"Ah, but what number base was '42' in ?"
13 AFAIR. Find the question.
Re: Synthetic LPG
And just complexify the reactions a bit & you can go up the list of aliphatics & aromatics. Next stop gasoline, then kero, then diesel/gasoil. It's all rather energy-intensive but we've got all sorts of non-fossil energy technologies working their way up the inventiveness & optimisation slopes.
Let's hope the winner fares better than Harrison
He never got the full prize due to the same kind of political scheming that goes on to this day:(
The big problem with air travel is matching the energy density of kerosene and the power to weight ratio of modern jet engines. I suspect the future solution will be to manufacture synthetic kero from atmospheric CO2 and water, and forget about the energy inefficiencies of such a process.
Alternatively, we return to the age of the Titanic...
Re: 700,000 miles
No, it just has to be 2 or 3 times better than the average competent driver. And the more self-driving cars there are, which will presumably behave more predictably than the average punter, the easier self-driving cars will find it to drive amongst them. Us hangout meatbag controllers will also find the predictability something of a bonus.
Now Sergei, come and test it in the West End during rush-morning or rush-evening.
Re: Why do they always blame enterprise for slow adoption?
You've got a problem that's going to hit you where it hurts sometime down the road then. I'm assuming that people in your organisation use the WWW, so you need internal hosts to connect to external hosts using NAT, yes? Now, consider the case where some new company springs up (e.g. like Facebook) providing a service that becomes absolutely essential to your staff. But, they can't get any v4 addresses and have to go v6 only. Now, you could put in some kind of reverse NAT64 proxy that mapped internal rfc1918 address(es) to its v6 server addresses and faked up DNS to make it work internally. That would work, but you've now given yourself an almighty admin problem of keeping this stuff up to date, especially when more v6 only sites come online.
How close are you to retirement? Do you want to gamble?
Re: is this what.....
"but there's a lot of IPv4 network between me and other IPv6 islands"
If you use a tunnel broker, perhaps. Most of the Internet backbone carries IPv6. The BGP routing protocol anounces v6 prefixes. I have no problem getting to v6 hosts all around the world, and only a small fraction, if any, goes over v4 tunnels.
"Which is also one of the main flaws in IPv6 reasoning; the illusion that these addresses wouldn't matter (too much) because of DNS and ARP / DHCP. But if you're fixing network related problems then the last thing you want to do is rely on "automagically" assigned addresses and the likes."
IPv6 went to a lot of trouble to make this work well, and the link-local stuff in ICMPv6 for neighbour and router discovery 'just works'. In my internal network inter-machine connections such as ssh use a range out of my allocated prefix plus the automagic bottom 64, and the link-local stuff just carries ICMPv6. The default route automagically appears as the link-local address of my firewall/gateway. It'll be a bit more complex for bigger networks but all the router manufacturers have screeds of info on how to configure it, either statically or via v6-aware routing protocols. And it's all readily Googleable!
There won't be one. There is enough v6 expertise around that the v4 crunch will (eventually) be solved by moving to v6, despite the grumblings, and probably with some extreme tantrums along the way, judging by the comments on here.
I've had v6 for years courtesy of Entanet, though I had to build my own firewall/gateway router.
Sadly many manufacturers are still in ostrich mode though. I recently bought a TP-Link TL-WA901ND access point to replace a venerable WAP54G. It worked fine for both v4 and v6 in a basic config, but when I wanted to set up a guest SSID the problems started. SSIDs on a VLAN didn't support v6 at all and the v6 router announcements on the default (untagged) VLAN1 leaked into the guest SSID(!). In correspondence with TP-Link they said this device would never support v6. Luckily there is a OpenWRT build for this device, so reflashing and configuring and I now have fully working v4 and v6 on both main SSID and guest SSID. Thanks OpenWRT and a raspberry to TP-Link!
Re: just a thought
It would need a retro rocket motor to cancel enough of the ISS delta-V - essentially changing the orbit so that it intersects the atmosphere at some point. It would be an interesting targeting problem to hit the atmosphere high enough to give it a gentle enough deceleration. However I suspect that friction would still do for it as it got lower.
Re: Missing a servo????
Will the canards give you enough roll control, being close in to the fuselage? Are you expecting to have any aerodynamic control at launch altitude?
AFAIK a fatwa is just an instruction. The famous one regarding Salman Rusdie was an instruction for the faithful to kill him, but this one is apparently just an instruction not to go to Mars.
"in their defence the GPS manufacturers were apparently a little lazy, and didn't keep within their band - hence the interference"
That's a fundamental misunderstanding of the situation. GPS is a weak signal that transmits *within* it's alloted band. The receivers have to be sensitive, so can't use very selective front-end filters. That's OK because the bands either side were *supposed* to be space to earth bands for other services, therefore they wouldn't interfere with GPS receivers. Now, along comes Lightsquared trying to bounce the FCC into allowing them to run earth-based transmitters in the adjacent band with *much* higher local signal levels. The GPS manufactuers worked within the parameters they were given, and it has become a supremely successful service on that basis. I don't see how you can fault them. It's all on Lightsquared's crazy business plan, which should have been strangled at birth.
Re: 5 minutes to midnight?
I think I'll opt for sex with the barmaid instead. It'll definitely be a case of coitus interruptus a bit later though!
The going rate for scapegoats is quite good now!
I doubt even he could rescue the timescales, as they will be driven by physical limits, such as duct space, fibre supplies, staff who know what they are doing, etc, etc. Therefore when he fails he will be ceremonially slaughtered at some future time, given a quiet slide into some sinecure and a decent pension wedge. Meanwhile he has a nice salary to ease the pain of attempting to do an impossible job with a government minister sniping at him.
The service offering appears to be similar to that from XM Radio in the US, but that is delivered by satellite. I guess no-one was able to put together a viable business plan for a Euro-wide XM lookalike. Even the US one has had its problems. Nevetheless I've used XM in hire cars & with friends on one or two US trips, and it works well, even in the middle of Yellowstone Park where mobile coverage is all but nonexistent. Perhaps the dense mobile coverage in Europe makes it more viable, but it really needs a good multicast infrastructure over 3G/4G to make the economics work.
Sounds like he's decided to pull out his last few remaining teeth:(
ESA TV vs NASA TV style
I watched the launch on the net, plus some of the canned guff they showed beforehand. I must confess I far prefer the rather more minimalist NASA TV style, with a "just the facts, Ma'am" approach. The ESA commentators felt they had to fill the silence all the time, and the beforehand guff looked rather like the work of a wannabe Jean-Luc Godard. A bit like 'Noddy launches a Satellite' instead of an Open University production.
CCTV was much more impressive covering the Chinese moon landing too.
Re: If the rollout down here is anything to go by
"No, down here they're rolling out to random villages and ignoring the towns with businesses crying out for it"
?? Isn't this supposed to be support for *rural* broadband? Having said that, around here BT seem to be upgrading the cabinets in our small towns that they weren't prepared to pay to do themselves, rather than concentrating on the villages which is what I naïvely supposed was the point of the exercise.
Governments will never take a financial risk that is obvious as such to the electorate, and, as taxpayers, should we really expect anything different? The best way government can help is to set the legislative & policy landscape such that private capital finds it easier to support innovation like this, and for innovators to find the private capital. But Labour really doesn't like that idea. There is a reason why VCs in the UK (if there are any that really deserve the term) are so much less obvious than VCs in the US.
Re: 80k km apogee?
For info, NASA's GMAT mission planning program suite has this exact GEO mission as one of its included example scripts. http://gmat.gsfc.nasa.gov/
80k km apogee?
GEO is about 42k km radius, so I wonder why they overshoot it like that. Perhaps it means less delta-V requirement on the satellite motor to raise perigee.
GTO is highly ellptical with the apogee up close to the GEO altitude and the perigee only around the altitude of Low Earth Orbit. An extra motor on the satellite fires around apogee to bring the perigee up and circularise the orbit. It also often changes the inclination by a few degrees to bring it right over the equator.
Wintel irrelevance == x86 irrelevance
The domination of the Wintel desktop is the only thing that's keeping x86 alive. It was a crap architecture from the off, and all the hoops Intel have jumped through to try to improve it would have been better spent by junking it early and coming up with something new. The problem with that was - they came up with Itanium...
That could have been an interesting idea but the execution was terrible.
IMHO it was very sad that DEC came up with one of the best CPU architectures ever (Alpha) just at the point when they were going bust for other reasons. Intel should have bought the IP and the designers from DEC and run with that but by that time they were far too heavily invested in x86 both financially and intellectually.
Re: What a silly thing to do
Exactly. NASA get far more bang for the buck with the unmanned probe programme they already have. Tito ought to go & read Cervantes instead of Robert Heinlein.
It looks like the first part of the flight is a full-on spin. I wonder if it comes out of that automatically or whether a spin recovery action is required (AFAIR full opposite rudder, elevators forward until spin stops then centre rudder & pull out of dive). Fortunately it's not a flat spin...
Judean Peoples' Front
Internecine warfare is always more satisfying than confronting the common foe. Because it's usually easier.
"Currently, it seems that Thorium Molten Salt reactors are the way to go".
Definitely, but it's going to be several years before practical & economic designs for both large & small Thorium reactors are available. So we're stuck with a generation of PWRs to be built. As a stopgap we also need enough gas-fired plant on stream to get us through the next decade.
Colour me unimpressed
In the average, they might just have a point, but for some of us it's just a complete wind-up. I've got ADSL2, not even 2+. Until recently it was over 4Mbit/sec mostly, but it's recently dropped to about half that, as the SNR margin has vastly increased - not sure why yet. Our line is direct off the exchange 2.5km away so 'superfast' fibre kit is pointless over that distance. There is a cabinet 150m away but there seems to be zero chance of getting connected to it, even if they ever put a fibre cabinet there. Our County Council has a deal with BT using the Govt's (our!) cash, but the first results seem to be fibreing up the remaining cabinets in the local towns where it really ought to be BT funding that, rather than sorting out the really rural parts.
Re: Don't worry!
I can tell you exactly where it'll hit - not NY or DC, but Yellowstone Lake. 2 Ameriapocalyptos for the price of one. Those survivalists in Idaho will definitely be in the wrong place!
Viscous gloop isn't going to be that great as a coolant. The viscosity just slows down the convection needed to carry the heat away. You need a thin liquid, or even better, a thin low boiling point liquid with a large latent heat of vaporisation. In that case the liquid boils on the hot components. That technology has been used for decades for high-power thermionic valves.
Cisco would probably want some control over that, since it's the base OS of their big routers.
Re: Not unlike real gold
"It's the best heat conductor/diffuser around too. Apparently a solid gold frying pan is the best way to fry an egg"
Copper is better (~400 W/m.K versus 318 W/m.K) and silver is even better than that (~430). However, for real egg-frying goodness, you need the ACME *Diamond* pan (>1000 W/m.K).
Google/Wikipedia is your/my friend here.
Flight profile after release?
Have you designed this yet or is it still a secret?
Re: The UK's position
One of the problems is that, over decades, leap seconds will need to be added more often as the earth is slowly slowing, and the standard second is actually derived from the earth rotation rate sometime in the 19th century. However I think it is stupid to address this problem now. We can leave it to the boffins a century or so hence. Meantme there is Y2038 to get through...
Re: For a few dollars more....
A Fistful of Travellers Cheques is the training video...
Same launch point?
Or is that a function of the wind forecast on the day?
Looks like the ghost of James Jesus Angleton stalks the halls of Langley again, and Ft Meade.
Re: Clever or stupid?
There are written down procedures for destroying classified stuff, which is presumably what the Govt would treat it as. Those are effectively written on Tablets of Stone with the Blood of Sacrificed Virgins, so have to be observed TO THE LETTER, however stupid this is in a particular case.
Re: The physics of lava lamps are complex
That's probably why, in a General Studies session at my old school (back in the 60s), the art teacher made some irritatingly dismissive remarks about lava lamps. That's probably the point when I decided that arty people have nothing useful to say and subsequent experience has only reinforced that view.
Yes, but your absolute position could be anywhere within the ~10m GPS error ellipsoid if INS slaves off GPS initially. INS systems on aircraft can be initialised on the ground to the exact aircraft location, which is painted on the hard stand or a signpost where it parks.
The clue is in the K
Kinematic. It works on the move. Standard surveying techniques using GPS work best with fixed stations occupying a site for a while. You can get millimetre accuracy doing that & track continental plate movement. RTK, as has been said, has been around for a long time but at silly prices. Some early 'Consumer' GPS receivers would give raw carrier phase output and, with the right software, would give quite good results. I played around with a Garmin receiver and RINEX files from the Ordnance Some years ago. Unfortunately most consumer GPSs have now lost that facility, probably for market differentiation reasons. However, RTK needs better receivers to allow to track the carrier phase without phase slips whilst on the move. If this crew have cracked the cost issues for doing that then this could be quite interesting. It still needs a local fixed reference station on a known site (to the millimetre) to work properly though.
Companies have a fiduciary duty to endeavour to maximise return to shareholders, so it makes sense for them to spend some effort on minimising (legally) their tax liabilities. In this case company law and the aspirations of government to maximise tax revenue are in conflict.
As Eric Schmidt said, if legislators don't like the current legal tax arrangements it's within their remit to change the law. And to do that rather than posturing and grandstanding in parliamentary committees.
2 spaces per level for me. Tabs mean any significantly nested code just disappears off the RHS of my screen or, worse, gets wrapped by the editor. I put the opening curly on the same line as the 'if' and the closing curly in the column below the 'i'. 1-statement blocks don't need curlys. Statements in the block are indented. Works for me, but feel free to flame or downvote.
I was sceptical at first, but reading the article, this looks very interesting. An antenna noise temp of 40 millikelvins is not to be sniffed at!
Subeditor, hallo?! yoo-hoo!
GPS transmitters? They are way above us, and in the spoofers' kit, not in the ship's kit. I read El Reg for *accurate* reportage & interesting comment. Please maintain standards.
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