* Posts by Tim 49

24 posts • joined 11 Jun 2009

Let's go space truckin': 1970s probe Voyager 1 is now 14 billion miles from home

Tim 49

Gladdens my jaded heart to find fellow DP aficionados in places such as these.

UK lockdown easing heralds the return of burgers... and bork

Tim 49

Re: Fast food and IT just don't mix

"Chick-fil-A, which will any day build the promised location within 5 miles of home instead of 25".

Colo(u)r me perochial, but Chick-fil-A NO! we will not make you throw! (rinse, repeat).

Microsoft drops a little surprise thank-you gift for sitting through Build: The source for GW-BASIC

Tim 49

Re: Not bad for the year -- but they may not be telling us everything

My first job in '86 as a new graduate was programming in PL/M on a huge, heavy blue MDS - double 8-inch floppy drives, with one disk for the system & the other for the code. Loved the clunk...clunk noises as the heads banged about during compilation. IIRC, we had an extension card so we could compile for the 8086-family in addition to the native 8085. They were on the way out when I joined, but still required for those working on System-X networking kit, which was being rolled out.

The MDS was networked to (I think) an NRM - a white really expensive server, about the size of a chest freezer, which also allowed serial-port-networked MS-DOS PCs to access the file system. It came with a multiplayer maze/shooter game called Snipes which ran on the client MS-DOS PCs, & the office used to ring with the yells of the slaughtered.

We subsequently bought two Intel ICEs to do embedded 80188 development - these were the beasts with the great spider cables, which as the OP states, were plugged into the target system, having removed the target's actual CPU. I was working down in the bowels of our team-written embedded OS, writing C in MS C 5.0 (which had a preprocessor bug that couldn't correctly expand our huge macros, themselves auto-generated via Intel's AEDIT scriptable editor, run as part of the build process). Code had to be compiled, cross-linked, burnt to EEPROM, walked down the corridor, plugged in, powered up etc. in an endless cycle of fun, with much staring at oscilloscopes and HDLC protocol analysers. Strange what you remember - happy days.

'That's here. That's home. That's us': It's 30 years since Voyager 1 looked back and squinted at a 'Pale Blue Dot'

Tim 49

Is there much matter in Uranus?

(sorry, briefly thought i was 30 years younger).

50 years ago today Apollo 11 slipped the surly bonds of Earth to put peeps on the Moon

Tim 49

Omega Tau podcasts

Worth listening to several of the Omega Tau podcasts https://omegataupodcast.net/83-how-apollo-flew-to-the-moon/ for the interviews with David Woods & others. Useful in case you ever need to tell someone how to start an F1 rocket engine.

Take-off crash 'n' burn didn't kill the Concorde, it was just too bloody expensive to maintain

Tim 49

Re: Supre Cruise

Yes, SR-71 was a bit different though, because they could exceed M3. At those speeds, the compressor of a jet is almost becoming a drag item, & SR-71 bypassed most of the air directly through some big 'drainpipes' along the outside of the casing. They were essentially running almost like a ramjet at those speeds, with little compression & just igniting fuel in the airstream, running on reheat (afterburner for our left-pondian friends).

The big spiky-things at the front of the Blackbird engines moved forward & rearwards to manage the shockwaves. Unstarts in the intake could be extreme in the Blackbird, and at least one was lost because of this. A pilot's helmet was cracked by the force of his head hitting the side as the aircraft as it yawed during an unstart.

Concorde got the sweet spot of speed & performance. Trying to go faster would require more exotic fuselage materials & getting certification for safe operation faster than M2.abit with paying passengers rather than steely-eyed fighter jonnies would, I suspect, have been too difficult & costly - the Americans spent 1BN USD developing a faster passenger jet than Concorde & gave up.

As someone else says, there's tons of info on pprune, & there's also the heritageconcorde site, & several really good books, & the itvv.com Concorde flightdeck DVDs, which after many years are about to stop being made. If you're going to buy anything, get the itvv dvs.

Tim 49

Re: Supre Cruise

Bit of background, & a quick ramble. Jets work by ingesting air, compressing it, lighting it & shoving the expanding gas out the back, in a continuous process (unlike pistons, which are discrete such, squeeze, bang & blow of course). You can either accelerate lots of air a bit (modern high-bypass turbofans), or less air a lot (very noisy, uneconomical turbojets). However as you go faster, the efficiency of fans drops, & that of the pure jets increases, in simple terms because you need less 'compression' the faster you go. Also as you go faster, you need faster air coming out the back, & jets push the air out faster than fans (huge simplification here, please accept that!).

So for supersonic, you either need low-bypass fans, or pure jets. You also need loads of thrust. One way to get this big thrust is to use reheat, where you squirt neat fuel into the exhaust, downstream of the turbine, & light it, adjusting the nozzles at the back of the engine to compensate for the pressure changes at the back when you start this additional generation. You also want to keep some lower-speed & higher-pressure air coming out the back as well, in a 'cylinder' around the higher-speed supersonic air, in order to (a) make it quieter, & more importantly (b) to stop the cone of supersonic air expanding (diverging); you want the thrust to go straight back & not be wasted as the air expands in all directions.

Using reheat is horribly thirsty, but it means that you can have a lighter, "less powerful" engine for the majority of time when you don't need it. Generally, engines big enough to sustain supersonic flight would be massively overpowered for other times (and remember twin-engine airlines have loads of excess power too, since they must be able to get off the ground if one fails).

However, with careful magic in the intake & exhaust (and clever wings & fuselage to reduce drag), you can do away with reheat, & 'supercruise' on 'dry' power. There's a lot of extra drag when transitioning through M1.0, but it reduced again by M1.7 in Concorde's case, & she could then supercruise, on full dry power, with no reheat. Reheat all the time would use about 4x more fuel.

Concorde was unique here, with about 8% of the thrust coming from the engine itself, 63% from the intake, & the rest from the convergent-divergent nozzle system at the back. So supercruise is just very clever optimisation of the intake/engine/exhaust system to optimise power & efficiency at supersonic parts of flight.

The really clever thing is the intake on Concorde, where you're slowing the air down by 1500MPH in a length of 15 feet, without expelling a shock wave out of the front of the intake, since to do so would multiply drag, & bad things would happen (this is termed an Unstart). Managing this shock front an the multiple shock waves dynamically is an amazing thing.

Tim 49

The most amazing engineering

When the project was cancelled, the very next airframe would have been the 'B' model, with wings that were more optimised for low-speed operation, & more powerful engines that no longer required reheat, which even though it was only used for takeoff & for about 13 minutes from M0.95 to M1.7 was very thirsty. This would have enhanced efficiency, but none were built.

The engineering, particularly for the engine intakes, ramps & spill doors & their control was staggering for the 1960s. at M2.0, more than 60% of the thrust was generated from the intake, from energy recovered from the pressure changes, with vary rapid adaptations for temperature, air pressure, demanded power etc. Concorde could lose two engines at M2.0 on the same side with no fuss, other than very rapid deceleration.

Even things like the tyres were radical, since the delta produces no lift until rotation, unlike conventional wings that start to reduce the tyre loads as speed increases. So you have an aircraft with a much higher take-off speed (1/2mv^^2 & all that), with all its weight on the wheels, requiring new tyre technology. And the main gear legs are too long to fit in the bays, so they have to shorten as they retract. Amazing, wonderful white bird, the like of which we'll never see again.

Details of 600,000 foreign visitors to UK go up in smoke thanks to shonky border database

Tim 49

Re: Problems

Fortunately I was also able to get an Irish passport. It'll help avoid the embarassment of people assuming I'm a "Little Englander" once the UK ones go blue again.

Three certainties in life: Death, taxes and the speed of light – wait no, maybe not that last one

Tim 49

As the late, great Mr Ian Dury succinctly put it: "There ain't 'arf been some clever bastards."

"Einstein can't be classed as witless,

He claimed atoms were the littlest.

And when you did a bit of splitliness,

It frightened everybody shitless".

Death of 747 now 'reasonably possible' says Boeing

Tim 49

Re: Last Chance To See

The only time I've ever flown in a 747 me & the missus got upgraded to Thai's "Royal Executive" class on the way out to Delhi in '92 - very nice start to a holiday. Would happily not have got off at the other end. Spent the holiday wondering whether it'd happen on the way back, but no such luck.

If you're into technology, https://www.itvv.com/ do really good cockpit DVDs & I've bought most of 'em: the Virgin Atlantic 747-400 is excellent, and the Virgin 747-200 shows how it was done in the days of steam. The Cathy 747's not so good, but has an interesting section in the simulator. Best of the lot is, of course, Concorde, on two DVDs.

The A320 simulator DVD's also good, with Alan Dix demonstrating rejected takeoffs & colourful ties.

We're doing SETI the wrong and long way around, say boffins

Tim 49

Re: Smarter than us

"...He sprang to his feet and saw to starboard, and not a hundred yards from their heeling, pitching boat, a vast iron bulk like the blade of a plough tearing through the water, tossing it on either side in huge waves of foam that leaped towards the steamer, flinging her paddles helplessly in the air, and then sucking her deck down almost to the waterline.

A douche of spray blinded my brother for a moment. When his eyes were clear again he saw the monster had passed and was rushing landward. Big iron upperworks rose out of this headlong structure, and from that twin funnels projected and spat a smoking blast shot with fire. It was the torpedo ram, Thunder Child, steaming headlong, coming to the rescue of the threatened shipping."

It didn't end well for poor old Thunder Child.

NASA's Orion: 100,000 parts riding 8 million pounds of thrust

Tim 49

Re: Bleedin' Dangerous

Commercial aircraft are squillions of times safer, and the degree of volunteeriness required to ride in them is different. It's not a fair comparison.

Tim 49

Bleedin' Dangerous

Just finished Mike Mullane's "Riding Rockets" about his jaunts in the Shuttle, and it's jolly unsafe, this space malarkey. At least Apollo had launch-escape systems, but for phases of the Shuttle launch, you were stuffed. Mullane states that the "Contingency Abort" checklist, to cover 'landing' in the Atlantic was there to "give you something to read while you died". If you got beyond that gate, the next was a landing in Africa or Spain, seventeen minutes after lift off, although they didn't carry their passports.

I never realised that you could get woken up by cosmic rays hitting the optic nerve, & appearing as a bright flash.

Bill Bailey: The man, the musician, the comic, the troll, the legend

Tim 49

"prostrate cancer"

It's a bugger when you lack the get up & go.

Last flying Avro Vulcan, XH558, prepares for her swan song

Tim 49

Re: It's wonderful, but...

It's not just the people. The rules around 'complex'-class aircraft are akin to modern airliners: there must be a full paper audit trail of every nut, bolt & widget, bonded-warehouses etc. There are no more zero-hour Olympyses, and RR no longer have the tooling or the processes to make them. As a commercial organisation, you can imagine the publicity if anything did happen to these 30+ year-old engines. Then there's the other critical systems and airframe fatigue - same applies.

People cite the marine Olympus, but it's a different beast: similar design, but non-aerospace components (weight doesn't matter in a ship, and aircraft generally don't eat salty air). 558's restoration only flew (ahem) because there were 8 zero-timed, bagged & audited Olympus 201s available from the old stock. Similar story with Concorde: without the approval of the Design Authority organisations, there would be no hope whatsoever of return to flight.

Tim 49

Re: Seen it a few times

Minor nitpick, but the Vulcan didn't have afterburners (reheat). It used either Olympus 201 (the ones in XH558, & the ones that can make the howl), and the more powerful 301 (which seemed never to howl), and were used in the Falklands missions. The two types were not interchangeable.

It's mostly lack of available engine hours that's going to ground 558, however like the other two live vulcans (and the two live Victors), she'll still be able to do fast taxi ground runs.

NotW accused of hacking Milly Dowler's voicemail

Tim 49

Don't buy the bl00dy paper.

If the general public are offended by the paper's deplorable behaviour, they'll stop buying the wretched thing. Anyone care to speculate whether in fact this'll happen?

Women would rather be on Facebook than on the toilet

Tim 49

"They also seem unconcerned about flashing their location".

Especially after six pints of Babycham.

BT boss brands Britain illiterate

Tim 49

I thought it was all scaremongering until...

I was tagged along with some others in a group in a facebook picture at the weekend , & the following day received this comment:

"wow piccys are good x mum looks well better now xx u with your friends look like u r at home xx "

What more can you say?

Vulcan kept airborne by £400k refuel

Tim 49

Please donate!

If everyone who saw 558 fly last year had coughed up a quid, there'd be no money worries. Sadly, most people don't. Airshows don't pay for the aircraft.

Head over to the VulcanToTheSky website & do the decent thing. You know you want to.


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