Comments by "Keit Hammleter" (@keithammleter3824) on "Found And Explained" channel.

@bradywomack9751 : Bearing mind this was supposed to be a one-time-use ramjet (disposable) I don't see why a coal engine couldn't be made to work. A friend of mine, on discovering that local sawmills had huge piles of sawdust that they couldn't give away and just burnt, decided to make a sawdust fuel turbine engine. He set it up in his backyard with the exhaust pointing straight up. He got it working (inefficiently), but combustion within the engine was nowhere near complete, and huge flames came out the exhaust. The neighbors seeing the flames phoned the fire brigade, who were not amused, and stopped the work. If one can make a sawdust engine work, one could certainly make a coal dust engine work, since coal, unlike sawdust, has less ash and negligible water content.
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@dannydaw59 : Yes. The energy density of lithium ion batteries is 0.3 MJ/Kg and lithium ion powered toy planes do fly. Lithum polymer batters can be as good as 0.9 MJ/Kg and have made all sorts of battery UAV planes practical and manned battery planes are being investigated. But batteries pale in comparison to coal, which gives 33 MJ/Kg - not as good as gasoline at 45 MJ/Kg but still vastly better than any battery, even after losses in converting to mechanical energy - about 90% for electric motors and about 47% for aircraft gasoline engines and around 55% for ramjets at the likely speed. Weight for weight we can expect a range around 60% of what you would get with gasoline engines.
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At 2:51 the narrator says airlines couldn't understand the need for jets. Not true. By then they were getting pretty sick of the high maintenance costs and frequent failures inherent in a large 4-engine piston engine airliner. E.g., 4 engines each 28 cylinders means 224 spark plugs to fowl up. Given a typical plug MTBF of around 1000 - 2000 hours that means an engine miss-firing and a fire risk every few flights. The USAF had the same problem, driving them to jets. Changing all plugs after every flight was acceptable in wartime, but not in peace time. Also, jets are smoother and quieter. Aircraft are noisy things, but if you have never flown on a large multiengine piston engine aircraft, you don't know what noise is.
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6 engines x 28 cylinders x 2 plugs per cylinder = 336 plugs. That's one of the factors that led to the B36 being withdrawn very early - it just took too much labour to keep flight ready. See my first post.
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@Sacto1654 : Utter nonsense. rounded windows had been standard on Boeing pressurised transports for years before the 707 or the Comet disasters. And on the wartime Lockheed Constellation. And the reason is that for sufficient strength the weight is less. There is nothing inherently bad about squared off windows - its a matter of competent engineering. All doors on pressurised airliners are square and they do not fail. This business about Comets and square windows was fluff put out by technically ignorant journalists who figured it was a good story they could sell to equally ignorant public. The Comet 1 had several crashes until permanently grounded for various reasons - faulty engine air intake design, incorrectly specified radio antenna that couldn't take the pressure differential, an inadequate riveting method, etc. All these fatal flaws were due to it being designed and engineered by incompetent inexperienced fools. It wasn't a case of other manufacturers benefitting from the Comet mistakes, it was a case of the Comet designers being too dumb and stupid to use what was already known by others. Finally, there was not A Comet crash investigation, there were about 10 of them (a couple of crashes reinvestigated when more debris was found), with some key findings kept secret until 2015.
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@markfrost8745 : Quite so. In the military, you follow orders. If it catches fire, execute the fire check list and hope. If you survive, well, you get ordered to fly again. In civilian use, after 2 or three fires reported in the news media no one would fly in the thing. No one wanted to fly in a Comet long after they fixed the design flaws. Anybody who thought it was reasonable to convert the B36 into a civilian airliner must have been smoking really good weed.
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@vincentmaddux2302 The Nimrod looked like a Comet 1, but was completely re-engineered. The Comet actually went through 4 major revisions but of course the Comet 1 crashes made it unsaleable to the public, and thus only the RAAF could be persuaded to take it.
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@GreenBlueWalkthrough : That was the root of all the Comet problems - incorrect rivetting, bad engine air intake design, radio antenna not specified for pressure differential, etc etc, all of which led to the crashes. They were competent to design & engineer unpressurised wooden aircraft, but not large pressurised metal aircraft. It was a bit like someone who built a nice model aircraft out of balsa wood and a 1 cc model engine thinking he now has the experience to build a Cessna 150. One would think that DeHavilland engineers should have had enough ethics to say to management, "Hey, this is above us, you better poach someone from a company that has built pressurised metal aircraft."
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I went to an airshow over 50 years ago, organised by a glider club. There were lots of gliders, Cessnas, and other small single prop aircraft on display, a helicopter giving rides etc. The local airline based at the capital city 150 km away sent over a Fokker F28 (mid sized T-jet airliner) - a brand new one they had recently purchased. It amazed the crowd - pilot threw it around the sky like a dog-fighting fighter jet, though he didn't quite get it upside down. I remember the commentator saying something like "Captain so and so and his co are enjoying themselves with this one-time opportunity - they can't do this with passengers on board - the passengers would vomit and/or black out."
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@josega6338 : The pulse jet engines, as devised by the Germans for the V-1, were not self-starting - they required launching from a powerful catapult. It would make the thing too complex and costly anyway. The idea was to have a dirt cheap disposable / one-time use machine that could be used by crews with minimal training.
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@colinpowell4788 : The V-2 was not a ramjet craft, and not a flying bomb. It was a ballistic missile powered by a rocket engine using alcohol (with water to reduce peak combustion temperature to manageble levels) and oxygen stored in onboard tanks. A ramjet would be useless in a V-2 as it flew far too high to get sufficient atmospheric oxygen, and also useless because the V-2 accelerated from rest on the launch pad under its's own power, which a ramjet cannot do.
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@williamzk9083 : Presumably you meant Walter Kaaden, who had nothing to do with V-1's or V-2's and barely out of college in WW2. He did his thing on 2-stroke piston engines in 1961, long after World War 2 had ended. I would be surprised if Suzuki used any industrial espionage of German innovation in their 2-stroke engines, as they developed their Posi-drive engines in the 1960's, which were disk valved, forced lubricated, used straight gasoline, and were unique. Perhaps you have come across a Facebook myth.
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@Trollwatch : Interesting. Wood flour could be air-injected as was Diesel's original idea, but would not be a clean fuel. The ash would cause severe wear. I take it that it wasn't based on burning wood in an air-starved external combustor, thereby producing carbon monoxide, which burns cleanly and effectively in a spark-ignition engine? This method is unsuitable for aircraft as the wood combustor was very large - typically the size of a large fridge when supplying a car engine. This method was not unusual in sawmills in the 1920's., and widely used to run cars on wood in Australia during World War 2. Gasoline was tightly rationed and effectively not available for non-work related use. Car owners either bolted the combustor on the back or towed it on a trailer. A trailer was preferable as it gave a longer range and the combustors were often home made and sometimes exploded.
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@obelic71 : You are not wrong re political interference. The Brabazon prototype reportedly flew quite well but it was an aircraft that no airline wanted, due to it being specified by an incompetent government committee led by politician Lord Brabazon who thought air travel was only for the rich and famous who would pay lots of money for luxury and privilige. All governments must appoint committees from time to time to solve problems or recommend decisions, as elected politicians cannot be everywhere and cannot know everything. But post-war British governments seem to have excelled in appointing unnecessary committees (eg Brabazon - the aircraft makers if left to themselves would no doubt had focused on actual market needs as you alluded to) or stuffing committees with people least likely to understand the issues. However, I disagree that British aircraft engineering was world class. Pre-war aircraft were simple and not very large, so British firms could keep up. But during the war, the US developed advanced very large transports and bombers and this experience and funding gave them immense advantages that only very large firms could leverage. The Comet turned out to be a disaster due to bad design and engineering by an incompetent team, pure and simple. They were like an ordinary nurse suddenly taking on brain surgery. It wasn't a disaster because it was the first jet airliner, it wasn't really a disaster due to bringing to market in haste (though a bit less haste might have helped), it was a disaster because multiple fatal defects were built in from the start through sheer ignorance.
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Did the script writer make this nonsense up as he went along? Dropping bombs on the USSR? Nope, they were not at war with the Soviets Needing a twin tail for low altitude flying? Nope - there is only one reason for twin or triple tails - reducing the height of hangars. Using it as 300-troop invasion transport? Nope - to invade the USA they would need somewhere around a million paratroopers - so 3,000 planes - no possible way could Japan make that many. The G10N only existed on paper as a concept and was just the head honcho of Nakajima smoking too much weed. Flying over thousands of miles of enemy territory, it would be shot down and never reach target. In any case, 3000 planes would require 18,000 engines imported from Germany - fat chance of that happening. The narrator claimed this plane could have worked with wartime German jet engine technology. That's pure fantasy. The German jeet engines consumed far far too much fuel, and couldn't last the duration of an intercontinental flight anyway.
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The only thing amazing about the Comet is the multiple fatal flaws designed into it by a totally incompetent set of designers working in a company with zero relevant experience. Boeing learnt nothing from it - they had heaps of relevant experience to draw upon and used quite different construction methods and design features.
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@williamzk9083 : It didn't actually work at zero speed. Actually, iwhen the fuel was ignited, pulsing would usually start with a lowish fuel flow without any forward movement of the V-1. But it was not proper pulsing and the thrust was minimal, well under that required for the V-1 to fly (well below the thrust required to achieve aerodynamic stall speed). On launch, V-1's were accelerated to over 300 km/hr by a catapult device, essentially a piston in a very long cylinder driven by a huge volume of steam created by reacting hydrogen peroxide with sodium permanganate. At nearly 300 km/hr the pulse jet began to work properly and produced full thrust, continuing the flight. You can watch a German training film on how a V-1 launch works at https://www.youtube.com/watch?v=YJ-dAFQ6Jzo. The catapult system was quite elaborate. The link you provided is not valid.
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@williamzk9083 : A water/coal slurry will not work in a diesel engine, as atomisation is critical to ignition and burst combustion, which must occur with a few degrees (10 or 15 at most) of top dead centre, or efficiency will be low. For the same reason, particle size would need to be well under 0.1 mm or the engine may not even fire. Remember - combustion is two processes - pyrolysis followed by oxidation. Oxidation cannot occur until pyrolysis has started - in a diesel engine this must be fast, so requiring particle surface area to be large compared to diameter. It should be fine in a turbine though - since combustion is continuous and can occur in as much volume as needed. The L13a (not L13) was meant to be simple and cheap, so pellet by pellet dispensing is no good. It was essentially a pre-loaded fuel cartridge system
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Well, at least the Model 37 wasn't as completely stupid as the British Bristol Brabazon - a monster prop airliner designed by a government committee (who thought that only rich people flew) that no airline was remotely interested in. But .... On of the factors in driving the USAF away from piston engine large bombers like the B36 and on to large jet bombers like the B52 came from when the B36 was deployed to an Alaskan air base. The general commanding the base wrote a blistering report saying it was just about impossible to keep the B36 flight ready. One problem: 6 engines each of 28 cylinders = 336 spark plugs. You could expect at least one random plug failure per flight, as each flight meant a total of over 3000 spark plug hours, and it just took way too long to change them all before each flight. To get the same overall reliability as say a B17, spark plug life would need to be 5 times longer - not possible. Similar reasoning applies to other components. The pusher configuration and misfiring led to serious fires. And it flew too slow to ever get to enemy targets before being shot down anyway. If maintenance cost is too high, and reliability too low, for military use, it is most definitely no good for civilian use. A few fires in the news and nobody would fly in the thing.
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"Many considered its design was weak." That is an enormous understatement. It was designed by an incompetent team and had multiple fatal flaws, as shown by eventual ground testing of a Comet donated by an airline.
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@williamzk9083 : I'll rely on the original German training films and manuals. They say that the engine cannot accelerate a V-1 from rest and make it fly. They ought to know. If the engine was good at zero speed as you claim, why on earth did they need the expensive catapult running on a very dangerous but dramatically effective propellant? Incidentally, in the metric system, jet engine thrust is measured in newtons. Thrust is a force, not a mass. The V-1 engine had maximum output of 3.53 kN at 750 km/hr, equivalent to 360 kgf. However, V-1's had a speed regulator that throttled the engine so as to run the craft at 550 to 600 km/hr air speed. It so happens that the speed achieved by the catapult was 320 km/hr. Did you mis-read your reference?
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@williamzk9083 : I told you - the link you provided is invalid. Provide a working link to a valid webpage and I may then be able to view it. Kaaden worked as some kind of assistant to the designer of the Hs-293 glide bomb, and later was flight engineer during testing the Hs-293. The Hs-293 was a radio controlled glider bomb, not a missile. Kaaden never had anything to do with missiles, and certainly had nothing to do with the V-1. It's no good you, without any backup, just repeating your implausible and unlikely claim that Suzuki copied or used industrial espionage to design their engines. What is your source? I note that Suzuki was by no means the only 2-stroke motor cycle manufacturer to use rotary disc valves in the 1960's. E.g., Kawasaki's 2-stroke was also disc valved. Same with Bridgestone. But Suzuki's motorcycle engine was unique in its lubrication system. It was also high revving with (by 2-stroke standards) a wide power band. It was unlike a tuned racing engine that really only functioned well within a narrow rev range - it was designed to compete with the Honda 4-strokes. Kaaden didn't invent rotary disc valves - Daniel Zimmerman did. Nor was Kaaden the first to think of or understand resonant exhaust tuning - an Erich Rolfe did that for m/c 2-strokes, 10 years before Kaaden worked on it. So, basically, rotary disc valves and exhaust tuning was just something the Kaaden and lots of others were working on in the 1960's - refining it, not devising it. You claim is implausible.
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@bradywomack9751 : I agree with you, although what the Germans were trying to do was significantly eased by intending it for a one-time use for a very short flight time. All the early workers in jets had their biggest difficulties with combustion temperatures too high for the available engine construction materials, causing rapid failure, or using ways of keeping teemperature so low efficiency was so low as to be useless. This problem does not occur to anywhere near the same degree in a piston engine because combustion is not continuous - it only occurs within a few degrees of top dead centre every second crank turn. The other 700-odd degrees of crank turn are available for heat to flow out of the cylinder head walls etc. If the P13a engine came apart from heat after 15-20 minutes it would not have mattered - its' job was done. Solving the heat problem in jets for Britain was Rolls-Royce's brilliant innovation, having an inner and outer combustion chamber with holes in the inner where the air goes in. This meant the inner chamber could be made of an alloy that withstands heat but needs no mechanical strength, while the outer chamber needs an alloy with strength to withstand combustion pressure, but is not subjected to heat. I think this thread was on the question "Could a coal fueled jet engine have worked?" The answer is clearly yes. On the question "Could it have been useful for normal aviation?" I very much doubt it. There is one very good reason why nobody has made a coal powered rocket engine - in most applications of rockets (as distinct from applications of jets), the weight of fuel at launch is the limiting factor. The energy content per unit mass of coal is much less than other fuels such as kerosene, hydrogen, etc. Coal could work but not very well.
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@Thinkle911 : I think you have overlooked a couple of things:- 1. The P13a engine design called for the coal to be in the form of small granules. How small is small? Unfortunately I don't know. 2. The design separated the locations of pyrolysis and combustion. The coal granules were to be heated in an air-starved "basket" thus producing carbon monoxide. Additional air was to be downstream mixed with the carbon monoxide and burnt. By separating pyrolysis and combustion in this way, the pyrolysis part does not require much air and can be a "slow" process in a large volume. This is essentially the same idea that enabled people to run cars on wood during World War 2. According to Wikipedia, a preliminary design was built and tested, and found to work but not very well. A better pyrolyser design involving a rotating basket was proposed as a result. However, no reference is given, so the Wiki author might be wrong.
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@Thinkle911 The wood burning gas generators used for cars were roughly about the size of a kitchen fridge. But there was no need to think of ways to make them small. One of the reasons for the size was so the driver didn't have to stop extra times just to stoke it with more wood. The energy density by volume of wood depends on the wood but for hard woods it is usually about 0.5 to 0.75 of the energy density of coal. So it seems feasible that a gas generator fueled by coal could be half the size or less, perhaps quite a bit smaller. The power output of a car engine running on carbon monoxide was reduced to about 70% of that with gasoline. Overall, I still think a coal fueled airplane for a short flight is doable, but it wouldn't be very good. I think you are right in believing it a gigantic waste of material. Only for if you are desperate, which in the later part of the War the Germans certainly were. They would have needed to get the thing good and hot before a flight. This could take sufficiently long such that the Allies could have defeated it by randomising their bomb run directions and times. The various sorts of Messerschmitts could be scrambled in a few minutes, as could Spitfires etc.
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@josega6338 : A model constructed in 1993 has no relevance to what the V-1 engine could do. It indicates self-take-off is possible in a light aircraft with 2 engines, but it wasn't in the case of the V-1 fully loaded with explosive (~2 tonnes total mass), even though the V-1 flew pretty fast for its' day. The video does clearly show that engine operation at zero airspeed is problematic - he had a lot of trouble getting the engines to pulse, although this could have been due to some fault in his set-up or design. The main purpose of the V-1 catapult was to accelerate the V-1 to a speed at which the pulse jet engine could operate properly and develop enough thrust to take over and continue the flight. That's what the original German training materials state. A secondary but still important function of the catapult/ramp was to point the V-1 towards the target (London), as the onboard flight control (compass and autopilot) was designed for a simple straight line flight. According to the German documentation, the stall speed of the loaded V-1 was 240 km/hr. The catapult accelerated it to 320 km/hr, considerably above the stall speed but sufficient for the engine to be certain to develop enough power to maintain the speed and accelerate as fuel mass was consumed. All types of jet engines, including pulse jets, essentially produce a thrust that increases with aircraft airspeed, as with increased airspeed, a given mass of air is forced in in less time, permitting a greater fuel flow for stochiometric operation. (In practice, modern jets may be restricted at high speed by the engine management computer in order to stay withing design stress limits at high speed but retain good take-off performance.) But with pulse jets there is an additional problem - at low speeds the pressure and flow conditions are not right for proper resonance, and while it may pulse, it won't pulse properly. You can watch a German training film on how a V-1 launch works at https://www.youtube.com/watch?v=YJ-dAFQ6Jzo. The catapult system was quite elaborate.
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@josega6338 : Actually, I'm none too good at following spoken German either, despite German parentage - not enough practice. But I can read German ok. You've got an extra f in stuffung. Aircraft carrier catapults are primarily for getting enough airspeed to be above stall in a short distance, and the relatively heavy weight of typical fighter planes (eg Crusader 15 tonnes take off mass) or observation planes requires an impressive catapult, even with propellers, which work just as good at zero airspeed. But the V-1 catapult was designed to impart a much greater speed to 2-tonnes of V-1 + fuel + warhead to get the pulse jet engine up to flying thrust, well above stall as I described.
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@josega6338 : You have ignored the point I made (true, repeatedly) - yes, the engine RUNS at zero airspeed, but it doesn't generate enough thrust for flight at zero airspeed. It has to be accelerated to near 320 km/hr before it can develop enough thrust to sustain flight. Unlike a normal airplane, a V-1 could not take off on its' own. It could not accelerate from a standing start to a speed sufficient for take-off, no matter what sort of runway was provided. or how long it might be.
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@josega6338 : I told you - how a modern day light weight model, probably 50 kg or so, with 2 engines of unknown design performs has absolutely nothing to do with how a wartime single engine that had to shift 2 tonnes performs. The original German training materials for the V-1 state that the aircraft has to be accelerated WELL OVER the stall speed in order for the engine to take over - they should know. Modern fighter jets can reach Mach 2 routine. By your reasoning that means any jet fighter can reach Mach 2, including the wartime Me-262 (which could barely reach Mach 0.8).
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@josega6338 : You claimed in your last post that the Me-328 model contradicts me. It does nothing of the kind, so I responded explaining why. You are being silly now. You can go imagine a MiG-25 with an engine from the Enterprise NX-01 if you like. Should get a speed of Warp 10, whatever that may mean. A pulse jet is the last choice you would want for a take-off engine. I told you, go back and read it again - jets of all kinds inherently produce thrust that increases with airspeed, so they are relatively weak at take-off, unlike propellors driven by piston engines or turbines. In addition to that basic weakness of all jets, pulse jets have an additional problem - as they are a resonant system (tuned for cruise airspeed), the pressure and flow conditions at zero airspeed are not as designed, and thrust is even weaker still - in fact they can be difficult to start, tending to blow flame instead of pulsing. A rough analogy is a racing bike 2-stroke engine - they are also a tuned i.e., resonant system and at RPM lower than intended produce little power and run audibly very rough, erratically misfiring.
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Found and Explained said that the Soviet Bison jet bomber was thought in the US to be able to bomb at supersonic speed. Highly unlikely - the Soviets would have to defy the laws of physics to achieve that. Perhaps he confused it with the much later M-50 Bounder, which could fly supersonically but most likely had to drop below Mach 1 to drop bombs (and never entered service except as a test bed).
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@obelic71 Bad rivetting was not the only problem. They ordered things like radio antennae from the usual supplier but didn't think to specify that they had to withstand pressurisation. So they didn't withstand pressurisation. Two Comets were lost because defective engine air intake design caused unexpected sudden loss of power on climb out.
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@alexander1485 : Much the same thing as far as stresses go - in fact stress is a little bit higher with sides different length to top and bottom. The term "square" in engineering means "at right angles" or "squared up in shape", not always "all sides straight and equal length.".
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@77ice11 : The second part of which of my various posts here? You are repeating a urban myth started by sloppy British journalists writing before all the various reports into the various Comet accidents were made publicly available. I suggest you read up on each of the Comet 1 accidents - each was due to a different cause. Of the 13 Comet 1 accidents, metal fatigue was identified as a factor in only 2. If you check the various large pressurised transports that Boeing and other US manufacturers had sold and were in use before the first Comet was even built, you should quickly realise you have it completely wrong. This urban myth that Boeing learnt from the Comet is based in part that the 707 came several years after the Comet. However, Boeing had pressurised all-metal experience going back to the B-29 bomber, in service during WW2, and with pressurised all metal large airliners in service before the Comet. Boeing did put out marketing that wing-root mounted engines was a bad idea (and it is, from both a structural failure mode and air intake points of view, but has handling advantages), but since they had never ever done such a thing, that in no way implies Boeing learnt from the Comet. Fatal Comet accidents include ADF antenna not specified for pressure and blew out in flight, sudden unexpected loss of power during climb out due to faulty engine air intake design.
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I certainly do not work for Boeing. I am a retired large diesel engine dealer engineer, and before that an electronics engineer based in Australia
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@77ice11 : Your descent into personal terms shows that you are incapable of contributing relevant facts. This was never about British people, nor about British engineers in general. My posts are about specific design flaws in the Comet, and the fact there were multiple and different fatal flaws in the Comet is proof that the particular engineers involved were incompetent. You cannot argue that they were breaking new ground in these flaws, as most related to pressurisation, and pressurisation was not new. ADF antenna (which necessarily must penetrate the hull = they ordered them from their usual supplier but didn't think to specify that they were for a pressurised aircraft; a riveting process unsuitable for a pressurised aircraft was used. Etc etc. Rather than being a case of other manufacturers benefiting from Comet experience, it was a case of the specific Comet designers being ignorant of what was by then well known in the industry, as the company had until then only made unpressurised wooden aircraft, even though such aircraft were by then standard elsewhere. Apart from the lessons learnt by British investigation authorities to lift their game (later investigations changed the findings of the first investigations), there is another important lesson in the Comet for all engineers, British and others - it is unethical to take on a task for which you have no relevant qualifications or experience. people can die if you do.
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@77ice11 It's not disputed that Boeing slipped up badly on 737 MAX - a failure of FMEA. However even the 737 MAX looks very safe compared to the Comet. There have been only 2 fatal losses of 737 MAX compared to 13 fatal losses of the Comet 1. The 737 MAX had a single fatal flaw. The Comet had multiple fatal flaws. The 737 MAX was grounded temporarily and then cleared for further use, and is to continue manufacture, as only a very minor change to airspeed detection was required - the aircraft structure is fundamentally safe. The Comet 1 was ordered permanently grounded and manufacture ceased, as the structure and fittings were not safe - the aircraft needed a complete redesign and a major change in manufacturing process. I don't doubt that less Boeings will be sold to airlines now, as Boeing have damaged their reputation, but that is another issue. You are the one with bad manners and the first and only one to descend into personal terms in this thread. You continue to imply that the Comet designers had no prior knowhow available to them - that was the case only within De Haviland. Your comment about CAD/CAM is irrelevant, as even where it was identified that metal was overstressed in the Comet, it was found to be stressed well beyond limits accepted as standard in the British aircraft industry at the time the Comet was designed. In other words, they failed to correctly apply what was already known. The ADF antenna blow out is not in any way imaginable to be due to not having CAD/CAM, or even someone counting on their fingers. It was simply due to someone in De Haviland ordering antennas from their usual supplier without telling the supplier it was for a pressurised aircraft. If De Haviland had requested pressure withstand capability, their supplier would no doubt have supplied a compliant antenna (probably at extra cost), or informed De Haviland they should go to someone who can. Pressurised aircraft were nothing new at the time.
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@77ice11 : If I am so unconvincing, why are you so upset about it? You can't give facts and just make stuff up. An interesting comparison between the Comet 1 and the 707:- Comet 1: 12 placed in service averaging 40 seats each and killed 411 people. Boeing 707: 865 built averaging 170 seats and killed 3039 people, Thus a seat the Comet 1 was likely to kill 0.85 people. A seat on a 707 was likely to kill 0.02 people. The Comet 1 was41 times as lethal. Actually, its much worse, because each Comet 1 was in service for only a year or 2. Boeing 707's remained in service for up to 20 years or more. No wonder the Comet 1 was the ONLY airliner type to be ordered permanently grounded. With each different Comet crash due to a different cause (one was lost due to tail spar failure, nothing to do with windows, metal fatigue) it is abundently clear the designers were incompetent.
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@77ice11 Of course there were more 707 incidents/accidents. THERE WERE VASTLY MORE 707's IN USE. You are like saying a GM Chevrolet car is mare dangerous than the Rambler, because there are far more Chevys in accidents, ignoring that Chevys outnumber Ramblers by huge numbers. The B707 WAS a far better plane. Another factor is that 707's lasted long enough to be operated by less ideal airlines as second and third hand planes. The Comet 1 operation life was so short and in so few numbers is was never anything than a new aircraft operated by premium airlines with an otherwise excellent safety record. If you are a potential passenger, what matters too you is the probability of the aircraft you fly on killing you, not how many others get killed in the same accident. So what matters to you is deaths per passenger kilometer. On that basis, the lethality of the Comet is stark - it stands alone. If the Comet 1 was any good, any good at all, how come the British government (which had a vested interest in keeping it flying) permanently banned it from passenger service? The Comet 1 is the only western airliner so banned, ever. Even the Douglas DC-10 was allowed to fly after the doors and a couple of minor issues were fixed. As far as I know, there was only one other airliner banned forever from passenger service - that was the Russian "Concordski" TU-144, though it was allowed to operate as a freighter for urgent freight, and it was apparently regarded as too expensive to operate in passenger service anyway, limiting its passenger application to heads of state and top government officials.
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@77ice11 : You are the one who just doesn't get the point. You talk about public data, but you don't understand the data. Sure, various western airliners have been grounded - until the problems were identified and corrected. Then they were cleared to fly again. Of all western airliners, only the Comet 1 was permanently grounded. For instance the Concorde, although another British design aircraft with safety standards well below things like Boeing 747, is not permanently grounded - but it doesn't fly because the 2 airlines that flew it no longer see it as profitable. The Yak-42 was indeed grounded due to a single flaw, but later returned to service. The problems with 737 MAX are clearly embarrassing for Boeing as it is a clear failure of FMEA as I previously wrote, but only one fatal flaw has been identified - that is far and away better than the Comet 1's multiple fatal flaws. The Comet 2, 3, and 4 don't count as no airline put them into wide use, and they had a lot of changes wrt Comet 1. The Nimrod doesn't count - it is a military plane (actually a Comet 4), and the military do lots of things that are necessary but too risky for airlines. It's choice was influenced by political considerations, and using up Comet 4 hulls that could not be sold to any airline. The 737 Deamliner doesn't count because no hull losses or fatalities occurred. This idea that other manufacturers learnt from the Comet 1 mistakes is an urban myth, propagated by sloppy journalism. For the facts, go back and read my previous posts. Boeing 737MAX - returned to service 9 December 2020. Boeing 787 - no fatalities and no losses. The 787's problem were batteries and engines supplied by others - nothing made by Boeing was defective. production limited by the impact of COVID. Concorde - cleared to fly again in 2003 but the operators decided to retire it for commercial reasons. Yak-42 - cleared to fly again October 1984. Still in service. Most Yak-42 incidents not due to any defect in the plane. DC-10 - cleared to flay again 1980, production continued until 1989. DC-6 - grounded 1947 but cleared to fly again 4 months later. Remained in service in small numbers until 1990! Constellation - cleared to fly again, in widespread airline use from 1949 and production continued until 1958. Made obsolete by the 707. It is worth noting that the Constellation, designed in 1943 and used as a military transport during WW2, was the first high altitude (and thus fully pressurised) airliner - giving lie to the urban myth that the much later Comet 1 provided new knowledge against American knowhow.
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@77ice11 : It would be difficult for me to be interviewed for a job at DeHavilland, given I was born in Australia, and have remained there ever since. You live in fantasy land. Various Comet 1's crashed for different reasons: Incorrect radio antenna not designed for pressurisation, engine air intake design faulty leading to sudden unexpected loss of power, faulty riveting, etc. etc. Look it up. None of these design errors have anything to do with American practice before or since. You can't even get your facts right. Comet 4 came out in 1958. The B707 first flew 1957 and its design goes back to 1954. The permanent grounding of the Comet 1 by the British Govt is important - it signifies they had no faith in it. No faith that there were not other as yet undiscovered faults in this aircraft clearly produced by a company incompetent to do so. And they had a huge political and financial incentive to give it every chance they could. Britain was broke then, they were desperate to get export income. Your equating the safety of the 707 with the Comet is utterly ridiculous. In a sense, the Comet 1 was a lesson in how to make a better aircraft - in the limited sense that it told the British authorities that jet transports were beyond DeHavilland and they needed to be watched VERY carefully. More importantly, it taught the British accident investigation authority that they needed to get far more thorough and professional than they were. Indeed, they initially blamed a couple of Comet crashed on pilot error, and later were forced to realise it was not pilot error at all. Claiming pilot error was a cop-out that never solved anything. The forced improvement in British accident investigation, and the lesson taken on in other countries, is the single important lesson from the Comet 1 disaster, applicable to all aircraft types. Perhaps this distinction between poor aircraft and poor accident investigation is too subtle for you. I suggest you thoroughly read and seen to understand sources before you post again. You have plenty of sources and search terms in my previous posts.
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