Maybe this project won't count since it was technically successful before it was cancelled, but the project was originally supposed to be much much bigger than it became.

Now, in recent years, a billion dollar project isn't that rare. Even a billion dollars for a single plane is not unheard of. But the Valkyrie bomber project cost 1.5 billion dollars--in 1950's and 60's money--and delivered two aircraft. Two. And then one got ran into by a friendly aircraft during a photo opportunity, and it was "the good one."

I first ran into the Valkyrie as a child. The museum now known as the National Museum of the U.S. Air Force is located in Dayton, Ohio. This put it on the route between my home and a set of relatives, and my dad indulged my budding love of history by stopping off. I was amazed by the biplanes, and entranced by the WWII warbirds. The jet fighters were pretty neat, too. But then we ended up in the big hangar. I went from plane to plane, making my way around the displays. I eventually ran out of hangar to explore, and was next to a wall. I looked up. I was staring into six of the biggest engines i had ever seen. I scampered around to find more information.

As it turns out, I was looking at the only surviving example of a heck of a plane. It was designed to fly at Mach 3 at over 70,000 feet to strike targets in the Soviet Union. The fact that it could achieve those feats starting in 1964 was astonishing. High and fast seemed to be the answer as it would take the plane well outside the range of antiaircraft fire and discourage fighter attacks at the same time.

But, those same figures were its downfall. Designed as a high-altitude penetrator, it was supposed to fly higher than anything that could bring it down. However, developments in anti-aircraft missiles meant that the Valkyrie was quite within range from the ground. And when you tried to go in low--like the B-52 was able to do--the tradeoffs necessary to achieve those lofty figures quoted above were just too drastic. The Valkyrie was barely faster than a B-52 on the deck, and its fuel economy left a good deal to be desired. Also, the bomb bay was limited in relation to the Stratofortress. The Valkyrie was an engineering marvel, but it was made obsolete before it was even built by the engineering marvel of the anti-aircraft missile.

There was just enough momentum in the program to get two examples built. The first one had some problems in its construction, as there were some new processes being used. The second example righted many of these problems. Then there was a request for a photoshoot. Sadly, one of the pilots flying an F-104 fighter in formation with the larger bomber got too close, and the wings of the two planes made contact. The F-104 pilot and one of the two pilots of the Valkyrie were killed. That happened in 1966, and the remaining plane was retired in 1969. That is when it was flown to Dayton, there to wait until it astonished a young kid with six huge engines. It's still there, in the R&D gallery. Admission is free, and I could easily be talked into a meetup since i'm in the area.

I've got a whole bunch of material stocked up, and ready on cancelled RN design projects. This answer's just going to cover capital ships cancelled before the end of WW2, but if people are interested, I can post more on smaller ships, and post-war projects.

Post WW1 Capital Ships:

After the First World War, the Royal Navy took stock, and realised it had a challenge to meet. While on paper, it was the most powerful navy in the world, this ignored many of its weaknesses. Most of its battlecruisers and battleships were armed with 12 inch guns, and had been worn out by the stresses of wartime. The US and Japan were both planning ships armed with 16in guns, and larger weapons were expected. Even the latest generation of British ships, armed with 15in guns, would be outmatched by such ships. New capital ships were badly needed.

The design process for the armament of these ships began in March 1920, with an 18in 45cal gun (with a length 45 times its bore) being developed from the 18in 40cal designed for HMS Furious. Design work was started on a 16.5in gun for the battlecruisers, but this would later be changed to a 16in. Experiments on triple mounts were carried out using the monitor Lord Clive with an improvised mounting for three 15in guns. These showed no interference between shells, and so triple mounts would be accepted in designs, though twin mounts were still preferred. Tests suggested, erroneously, that lighter shells would be preferable for these guns.

In June of 1920, the first design studies were produced. A standard naming scheme would be used for these studies, with battleship designs receiving letters from L forwards, while battlecruisers* would start with K and move backwards. The number 2 was used to denote twin turrets, whilst 3 meant triple turrets. A set of baseline L designs were produced, one with four twin turrets and one with three triples. The designs had their turrets on the centreline as usual, but oddly, they were all on the same deck. This was likely an attempt to lower the centre of gravity, and increase the stability of the ships. They were limited to a length of roughly 850ft and a beam of 106ft by dockyard infrastructure. Armour protection consisted of a 13in deck, an 18in belt, with a 12ft torpedo protection system and a 7ft double bottom against mines. The design progressed, with the ships losing their long sterns after research showed they had little benefit. The baseline 'L' design was developed into the L2 and L3 designs, and the corresponding K2 and K3 battlecruisers, all mounting 18inch guns. These designs returned to the usual scheme of superfiring turrets, but omitted the traditional armoured conning tower. The L2s and L3s had a 15inch belt, sloped at 25^o to the vertical, and were designed for a speed of 25 knots. The K2 and K3 were designed for 30 knots, and so had much thinner armour, with only a 12inch belt and 6inch deck. They had two funnels instead of the one found on the Ls. Once the designs were produced and assessed, it was thought that both sets were too big. The belt on the Ls was too short to sufficiently protect the ship, while the Ks needed more armour period. The Ks also needed to be faster, to match the American Lexington design.

The next set of battleship designs displayed a major change of style. Instead of having the engines in the centre of the ship, and guns fore and aft as was typical, the Ms moved the engines aft and the guns forward. This allowed a drastic reduction in the length of the main armoured citadel, decreasing the amount of armour needed. This gave rise to some problems – the after turret had a very restricted firing arc due to blast effect. In addition, the shorter belt meant that major losses of stability would result from damage to the unarmoured parts of the ship as only a small proportion of the waterline was protected. This was counterbalanced by the significant weight savings; the Ms saved 1500-1800 tons over the Ls. They had two shafts, and were expected to make 23 knots. The M2 and M3 designs, mounting 18in guns, were selected as the basis for further battleship designs.

Battlecruisers followed a slightly different trajectory. The J3 design was conventional, mounting three triple 15in turrets, two forward and one aft. The I3 design had the same layout as the M3, with 9 18in guns. She was, however, a long design at 915 ft, making her unable to dock at the major naval dockyards of Portsmouth or Rosyth. The I3 design was decided to be too big, and the smaller H3 designs produced. The H3a design was basically an I3 with the midships turret deleted, giving her only two triple turrets forward. H3b lost the forward, A turret, with raised turrets in the B and X position, while H3c was similar but with lowered turrets. Some of the weight saved by losing the turret was used to add armour, increasing the belt to a thickness of 14in.

The next set of revisions produced the ultimate battlecruiser design, the G3. This carried three triple turrets, in the same plan as the M3. It was originally designed with the 16.5in gun referred to earlier, but this was changed to the 16in in January 1921. The first design, with the 16.5in, had only a 3in deck over the machinery. Later designs increased this to 4in, with 8in over the magazines and half of the boiler rooms, and 7in over the secondary magazines and engine rooms. While this added weight, this was compensated for by losing part of the secondary armament (taking it from 16 6in to 12) and savings elsewhere. However, in the final design, the secondary armament was returned to its original strength. It had a strong AA armament for the time, mounting six single 4.7in guns and four 8-barrel 40mm 'pom-pom' guns. The design had two torpedo tubes mounted, over the complaints of the design teams. They would have been fast ships, despite cramped machinery spaces. A bet between members of the design team is preserved in the Ship's Cover for the G3s:

'Speed expected at full power. If any of these ships obtain an official mean speed of 32 knots over the measured mile – no matter what the shp developed – I will pay DNC £1. If none of these ships obtain this speed DNC will pay me £5.' Signed S V Goodall, witnessed C M Carter.

Similar developments to the M3 design led to the N3 design. This was 50ft longer than the M3, but generally similar in armament, speed and armour.

Four ships to the G3 design were ordered in October 1921. They would be suspended in November, and cancelled in February 1922. This was a result of the Washington Naval Treaty, negotiations for which began in November 1921. A limit on future capital ships of 35,000 tons per ship was put in place, despite British arguments for the limit to be put at 43,000 tons in the hope of saving at least two G3s. As the final design for the G3s put their displacement at 48,400 tons, new designs were required. These ended up producing the Nelson-Class battleships, which mounted nine 16in in three triple turrets. Unlike the G3s, these were all in front of the bridge. The Nelsons were heavily armoured, with a 14in belt and 6.75in deck, but could only make 23 knots. Due to the all-forward design, and excessive weigh saving, blast effects from the 16in guns were severe.

Had they been produced, the G3s would have been an excellent design. They were faster than many contemporary designs, and much more heavily armoured. They mounted a heavy anti-aircraft armament and extensive anti-torpedo protection and had taken to heart many of the lessons of the First World War. They compared well to WW2-era designs, with thicker armour than the American Iowa class battleships. The only ships built that definitely outclassed them were the Japanese Yamatos, with their 18in guns and much thicker armour. However, they had some issues. Their 6in secondary armament was mostly useless deadweight. Blast effects from the 16in guns would have made it difficult to fit and operate the masses of light AA guns that ended up festooning battleships towards the end of WW2.

* After WW1, the RN began to use battlecruiser to describe any fast capital ship, not just those with little armour. The Hood, despite her poor deck armour, had a belt sufficient to give a reasonable zone of immunity against her own armament, while the King George V class battleships would be referred to as battlecruisers during the early stages of their development.

Oh God yes I've been waiting for a topic like this. The amount of projects that Michelangelo could have done if he lived to be 300... one can only dream.

The most prominent project that Michelangelo never really finished was the Tomb of Pope Julius II, also known as the Warrior Pope to those of you more inclined to the many wars between the various Italian city-states. Amusingly enough, this commission was made in the midst of a host of other outstanding commissions that were promptly dropped by the newly-famous sculptor since, hey, when the Pope calls for you, you obey.

The original design was to be an eighth wonder of the world. Three levels of over 40 tragic figures each coming together to honor the life of the former cardinal Guiliano Della Rovere and his conquests. Michelangelo is estatic to have the opportunity to not only serve the most eminent patron in all of Christendom, but also to let his imagination run wild. He spent an eternity compared to his contemporaries in the depths of the quarries at Carrara, searching for the right blocks and imagining what could be carved from them. Unlike many of his contemporaries, Michelangelo throughout his life was inclined to spend large amounts of time within the marble quarries at Carrara. There he lived for 5 months inspecting and selecting marble blocks to be shipped (a costly and dangerous task) all the way back to Rome. Fortunately or unfortunately depending on your preference, three years later the Pope instead has Michelangelo switch projects from the tomb to the Ceiling Fresco of the Sistine Chapel, which will consume, and I mean consume the next four years of his life. Personally, I would think something else would arise that would make Michelangelo fall short of his ideal work somewhere along the world, but another part of me wants to seem what he could have done with a real stretch of time and a full arrangement of sculptures. A year after finishing the Sistine Chapel and resuming work on the tomb, Pope Julius dies, after which the contract for the tomb is taken up by Julius II's grand-nephew, Roberto de Nobili, a notably less appreciative man. The unfinished commission for the tomb would be a thorn in Michelangelo's side for decades afterwards until the commission was finally reduced to a more manageable size, especially since the succeeding Pope Leo X wanted his own commissions for Michelangelo to complete, and he was formerly Giovanni di Lorenzo of the Medici family and bitter rivals to the Della Roveres.

After which, Leo X would start Michelangelo on another one sadly unfinished masterpieces -- The facade for the Church of San Lorenzo. Michelangelo, as ambitious as ever, wanted to construct an all-marble facade for the church. Sadly, this project was also cancelled.

These aborted projects and potential masterpieces of Michelangelo go on and on. If only there were fifty of him! For example he had a standing invitation with letters of credit from the current Ottoman Sultan to construct a bridge in Constantinople. Michelangelo probably briefly considered taking up the offer after rather rudely turning his back upon the Medici Pope Clement VII in favor for the short-lived republican Florence, but instead chose to remain in Florence, where his whole family lived, and Clement, living up to his name, somewhat generously let Michelangelo off the hook after taking Florence, and allowed him to return to his dear commissions.

Perhaps the most amusing aborted project was one that Clement had been pushing for, and one that Michelangelo dismissed. It was to be a collosus, 25 braccia high, nearly fifty feet. After the Pope sent three letters to his childhood friend with no reponse, (they most certainly had known each other when they were young in the Medici palace at Florence) Michelangelo responded with biting wit-- that instead, the collosus be seated, at 40 braccia high (80 feet), with a dove-house in his head, bells ringing from his gaping mouth, a cornucopia for a chimney and to top it all all, a barbershop set up in its rump.

Some of the water projects that Marc Reisner describes in Cadillac Desert were pants-on-head bonkers. One of them even proposed to damn rivers in Alaska to create a reservoir the size of Lake Erie and then transport the water to the American Southwest. It went nowhere for obvious reasons, including the fact that the transmission cost of the water alone was something like three times the contemporary cost of water. It also would have generated enormous amounts of hydroelectric power for a population that had no use for it. But, while it's easy to dismiss this as pure fantasy, he makes a pretty compelling case that such projects were the natural extension the ideologies shared by and the competition between the two agencies responsible for water management, the Bureau of Reclamation and the Army Corps of Engineers. Both were obsessed with building the biggest dams they could, and both were more than willing to construct environmentally and economically ridiculous projects for the sake of it.

Finally a topic I can wedge myself into! How about some scrapped operas?

There are of course no doubt an unknowable pile of operas that were started and later thrown in the fire, never to make a blip on the historic record, but for the Big Wigs of Opera Composing, we have two examples of dropped operas that tease us all with what might have been.

From about 1778 to 1780 Mozart tried to write an untitled comic opera about a super-hot-and-sexy topic at that time: white people being enslaved in Arabian harems. He got about 2 acts written, but gave up on it before doing the third act and the overture. Around this time he was looking to impress the Emperor Joseph II and land himself a comfortable gig as Kapellmeister, so someone suggested he send the Emperor a German comic opera for his new National Singspiel to get in his good graces. Mozart was a bit fussy about that because he had wanted to get out of the comic opera business and write serious stuff, as he complained to his father:

You should not have sent me the letter from Heufeld, it made me more annoyed than glad. The fool thinks I'll write a comic opera.

Mozart doesn’t mention this scheme again, but it’s likely this opera was intended for this use, as his father in another letter makes mention of preparing it for Vienna, where the Emperor had his Singspiel. In April 1781 he makes his final reference to the opera, to mention that it has been scrapped:

Concerning Schachtner's operetta, nothing can be done because of the same reason that I have so often mentioned. The younger Stephanie is going to give me a new piece - as he says, a good piece - and if I am not here, he will send it. I couldn't disagree with Stephanie. I only said that besides the long dialogues, which could easily be changed, the piece is very good - but not for Vienna where they would rather watch comic pieces.

The “new piece” he was given was very thematically similar though: Die Entfuehrung aus dem Serail, which was completed and was highly successful. The scraps of the earlier harem opera were found by Frau Mozart in his papers after he died, and it was named Zaide in the 1830s. It’s also been performed, with a few additions, since that time.

Zaide does represent a time of some significant developments in Mozart’s style however: it shows a more collaborative relationship between him and his librettist; experimentation with aria forms, and also some early experimentation with mixing comic and serious registers, which he would use to great effect in later operas. And of course, despite his efforts to get out of the comedy business around 1779, that is where he knows his greatest historic success in opera.

(written based on “'Zaide' in the Development of Mozart's Operatic Language” by Linda L. Tyler

For Rossini we have an unfinished opera that is also lost: Ugo, re d'Italia (Hugo, King of Italy), which I don’t think he had any intention of finishing.

In 1823 Rossini, at the height of his fame, was brought to London to compose an Italian opera (and perform in it). He also had 6 of his older operas staged this season, which he conducted. He maybe wrote the first act of it, and it was maybe deposited with King’s Theater, or the bankers, as The King’s went bankrupt that year (they did that a lot), after which Rossini, not being stupid, presumably didn’t work on the opera any further. Not to worry though, he and his wife (at that time, the legendary Isabella Colbran) were popular as heck in England and made out like bandits with money from fans for appearances and singing lessons, then went straight to a lucrative contract in Paris. Rossini looked out for Rossini, rest assured.

“2 packets of score” ended up in the hands of the bankers, and Rossini attempted to get it back in 1830. This indicates to me that it might have had some decent original work represented, as Rossini was a notorious recycler and maybe he wanted to recycle something from it. In 1831, determining they had no use for the opera, the creditors signed it back over to Rossini, and deposited it with an English law firm working for him, and that is our last record of the documents.

(written based on “A Lost Opera by Rossini” by Andrew Porter)

Keeping it short:

Chairman Mao and the end of Chinese characters

In the early 1950s Mao Zedong wanted to move the Chinese writing system to an alphabetic one. This became a major push, and also caught up in the alphabet fever was a large number of minority languages spoken in China, for which alphabetic orthographies were developed. Some of these took heavy influence from the Soviet linguists working in the regions.

As for Chinese itself, multiple drafts were created, including 4 based off Western writing systems (cyrillic included) as well as of native Chinese strokes. Eventually in 1957 the currently used hanyu pinyin system was adopted officially (though few — even among those working in the Academy of Social Sciences and Ministry of Education — actually bother to mark tone like they're supposed to).

Despite adoption the writing system in 1957 and it's later adoption in Taiwan in recent years, what didn't come to fruition was Mao's desire to have Chinese characters replaced entirely by the alphabet.

Ironically, Mao's calligraphy is now quite well known. Go figure.

My MA thesis concerns a few of the figures involved in Operation Paperclip, so here goes:

Everyone knows about the famous German V-2 rocket. What they don't know about is all the rockets that the German rocket engineers planned later. Now, you might say that their work in the US and the USSR were the fulfillment of these ideas, but these were the rockets they had planned to make in Hitler's Germany.

A note on terminology: the V-2 was called the A-4 by the engineers who designed and built it (A for Aggregat, which means "assembly"). The A-4 was a natural development from its predecessors, the A-1, A-2, and A-3. The A-1 was Wernher von Braun's first attempt at a liquid-fueled rocket and was quickly redesigned into the A-2, which first flew in December 1934. The A-2 was 1.61 meters long (5.3 feet) and weighed 107kg (235lb) with fuel. Next, they scaled up to the A-3 between 1935 and 1937. It was 6.5 meters long (22 feet) and weighed 750kg (1,650lb) with fuel. The A-3's engines worked well, but there were no truly successful flights due to guidance system issues and the rocket team moved on to the A-4/V-2. The A-4 was 14 meters long (46 feet) and weighed 12.8 metric tons (28,200lb) with fuel. It was designed between 1939 and 1941 and first flew in 1942.

Less well-known is the A-5, which was an improvement of the A-3 used as a guidance system test bed. About three dozen flew between 1938 and 1943.

The A-1 through A-5 were all the rockets that were actually built in Germany, but the rocket engineers actually had designs or theoretical designs for an A-6 through an A-12.

The A-6 was an improvement on the A-5 with a shortened engine. It was cancelled in September 1939 to focus all efforts on the A-4.

The A-7 was an A-5 with wings, the hope being that the missile could glide to extend its range. The project was canceled in October 1942, but two engineless prototypes were dropped from aircraft in late 1942.

The A-8 was the first true intended successor to the A-4, the main difference being a new type of fuel that could extend the missile's range (the production A-4 had a range of 270km/156 miles, the A-8 was theorized to be able to fly 450km/280 miles. The concept was dropped in mid-1942.

The A-9 was an A-4 with wings, with the hope that the gliding wings could extend the range of the missile to 5,000km/3,000 miles. After a suspension of research from October 1942 to June 1944, it was re-designated the A-4b in October 1944 so it could use resources from the A-4 project. Two A-4b/A-9 rockets were launched in the winter of 1944-5, but with a different tail than was planned.

The A-10 was another proposed A-4 successor with a much larger engine. The rocket team began seriously allocating resources for the A-10 as early as 1939, but it was dropped when the war started. It then came back in 1941 as a booster rocket for the proposed A-9 that would allow the rocket to hit the United States from across the Atlantic, but the A-9/10 was dropped in 1942.

The A-11 was a concept for a three-stage rocket using the engines from the A-9, A-10, and A-11 to launch a large warhead or a satellite. Theorized in 1940-1941, it never even made it to the drawing board.

Finally, the A-12 was a theorized at the same time (1940-1941) as another three-stage rocket using engines from the A-10, A-11, and A-12 to launch even heavier payloads.

So there you have it, the plans of the German rocket engineers for their future projects in Nazi Germany. As we all know, their dreams were realized through their participation in the American and Soviet space programs from the 1950s through the 1970s.

All info from The Rocket and the Reich: Peenemunde and the Coming of the Ballistic Missile Era by Michael J. Neufeld. Neufeld is a curator of WWII and Space Age history at the National Air and Space Museum.