Bespoke Planes designed for airline
Some work; some do not
Brequet 941 and Convair 990 Coronado NOT
Sometimes an aircraft design is driven by the needs of major customer, bespoke design and/or by technology advances developed by the aerospace industry. Oddly, not all of the bespoke models became market successes and others thrive. Above are four airplanes which demonstrate this divide:
- Breguet 941-designed to provide takeoffs and landings in tiny spaces;
- Boeing 727– a jet airliner to serve smaller cities with shorter runways (as short as 4,500 feet) and high-altitude airports;
- Convair 990 Coronado—designed to cruise faster than any other airliner-Mach .89;
- Boeing 747-400 –the fastest commercial airliner at Mach 0.855.
The Boeing aircraft were two of the most successful airliners in the marketplace. The stories of why these two models were so well received are well known. The Breguet and Convair did not have great sales.
Here are two informative articles about their histories:
During the 1960s, the incredible French turboprop was able to land on runways just 150 meters
Instead of spending hours on the way to the airport, you board an aircraft a few meters from your job and which is capable of taking off in less than 300 meters. It sounds like fiction but that aircraft existed, the Breguet 941.
Designed by the French planemaker created by Louis Breguet (and who would later join Dassault), the four-engine turboprop was designed to provide takeoffs and landings in tiny spaces. To achieve this capacity, the aircraft used a concept of large diameter propellers that covered practically the entire length of the wings with large deflection flaps (up to 100º) that directed part of the air flow to the ground, creating the effect that maximized its support at low speeds.
The result of this combination was an airplane that could take off in just 300 meters and land in an unbelievable 150 meters, or something like two football fields. And the Breguet 941 was not exactly a small aircraft since it could carry up to 64 passengers.
To put the concept into practice, Breguet built the experimental model 940, smaller and that flew for the first time in 1958. After proving its viability, the French manufacturer then went on to the most capable 941, whose inaugural flight took place on June 1, 1961.
The prototype of the Breguet 941: only customer was the French Air Force
The curious aircraft caught the attention of Americans, who were studying several STOL (Short Take-off and Landing) proposals, and in 1962 McDonnell entered into a cooperation agreement with Breguet to study the concept in depth.
At the same time, the US Air Force sent representatives to Toulouse, the company’s headquarters, to visit the Breguet 941 and assess whether it would be an alternative for the country. Until now, the turboprop was seen as a military transport aircraft, so McDonnell decided to take it to the United States for a series of demonstrations.
Renamed McDonnell 188, the French plane flew to America in 1964 and made aerial presentations at Andrews, Eglin and Wright-Patterson air bases, accumulating over 100 flight hours and 312 landings. However, when under the command of an experienced American test pilot, the Breguet 941 was damaged after an abrupt landing.
After repairs carried out by McDonnell, the turboprop resumed its flights in 1965, being presented to NASA and FAA, the US civil aviation agency. In April of that year, the aircraft returned to France with the impression that the tour had been successful.
The FAA even studied the rules for STOL operations at small airports within American cities
The McDonell 188 on a demonstration flight in New York in the 1960s
The passenger cabin of the Breguet 941 could accommodate up to 64 passengers (McDonnell)
In American and Eastern Airlines liveries
On its return to France, Breguet received the news that the government of the country had ordered four aircraft, but of the 941 S version, with a fuselage lengthened by 1.52 m, and that it flew for the first time in April 1967.
However, the US government, despite the good impression during its visit, showed no interest in the project, which made Breguet and McDonnell turn their eyes to the civilian market. After all, its peculiar characteristics would make it a great alternative for short flights operated from small central airports. The idea was carried forward and in July 1968 the Breguet 941 was back in the USA, now sporting the liveries of American Airlines and Eastern Airlines.
For four months, McDonnell 188 carried out 350 flight hours and made impressive demonstrations on small improvised runways. The turboprop became the subject of reputable magazines such as Popular Mechanics that highlighted the proposal to create airports in the downtown areas. According to the publication, the FAA even prepared some rules for this type of operation, which would require runways with a minimum length of 1,500 feet (458 meters) and the capacity to support a maximum weight of 150,000 pounds (68,000 kg).
By the end of the 1960s, jets were beginning to dominate air passenger transport and their operational requirements made airports too large. For this reason, the idea of a STOL plane departing from these small airfields seemed a very sensible proposition.
The defunct Eastern Airlines also evaluated the French turboprop
However, the Breguet 941 was an aircraft of a certain complexity and high maintenance cost. Its powertrain, for example, used propellers that were not directly connected to their respective engines in order to prevent a failure in one of them that could put the aircraft at risk. In its place, the manufacturer developed a system in which all the power generated was distributed equally to all propellers, something seen in helicopters, for example.
At a cruise level at 10,000 meters above sea level, the Breguet 941 reached 450 km/h, but its passenger cabin, which was quite spacious, was not pressurized. Breguet was even studying the creation of a circular fuselage version, the 942, but it did not leave the paper.
Inspiration for other planes
Videos at the time revealed that the Breguet 941 was really impressive. In a few meters, the plane left the ground slowly and landed in a peculiar way, with the nose lowered as if it were hanging on some “invisible hook”.
Despite the successful demonstrations, Breguet and McDonnell were never able to find a customer for the unusual plane. Only the four series airplanes were produced for the French Air Force that used them until 1974, proving that their concept was viable.
The American company, however, participated in a new competition from the USAF for a jet freighter with STOL characteristics. Its concept aircraft, the YC-15 used a flap system similar to the Breguet 941, and later became the well-known C-17 Globemaster III.
Interestingly, the problem that the French turboprop proposed to solve until today remains unsolved, the time and distance needed to board a plane. The most recent technologies, however, are betting on vertical takeoff and landing operations of points within cities. In a way, it can be said that 60 years ago, the Breguet 941, anticipated a future that we will soon see turning into reality.
The History Of The Convair 990 Coronado
- byMark Finlay
- July 5, 2020
Before the British/French-built Concorde defined what it was like to fly fast, another plane tried to push the limits of speed. This aircraft was the Convair 990 Coronado. Outside of the box engineering allowed it to cruise faster than any other airliner that came before it and quicker than any plane we have today.
The Convair 990 was the fastest subsonic airliner. Photo: Getty Images
All of this is amazing when you consider it was developed in the early 1960s for transcontinental flights. While it might have been busy breaking speed records, it was also breaking the bank.
The 990 was built following a request from American Airlines
Built by a division of General Dynamics in response to a request from American Airlines, the Convair 990 Coronado was a stretched version of the company’s earlier Convair 880.
The Convair 990 Coronado was 10 feet longer than the 880 allowing for between eight and eleven more passengers, which equated to between 96 and 121.
Despite the increase in passenger numbers, the plane was still unable to match the capacity of the Boeing 707 (110-189) or the Douglas DC-8 (105 to 173). The one advantage the Convair 990 had over its rivals was speed being 25 to 35 mph faster while cruising.
Coffee service on a SAS DC-8 in 1960. Photo: SAS
Speed, luxury, and sky lounges defined flying in the late 1950s and early 1960s. These factors are something that General Dynamics thought it had in abundance with the four-engine Convair 990. Looking to get a step up on its competitors, American Airlines asked planemakers if it could build a plane capable of flying from New York to Los Angeles 45 minutes quicker than was available at the time.
Boeing was not interested in building a plane faster than the 707
Boeing immediately refused with its engineers saying that it was already pushing the limits of subsonic speed with the 707. Convair, however, differed. It told American Airlines that it could build a plane that was capable of cruising at 635 mph (1,022 km/h). Convair even backed their new jet with guarantees to pay American Airlines millions of dollars in penalties if the Convair 990 was not as fast as it promised it would be.
Boeing was not interested in building a fast plane with the 707 filling its order book. Photo: Getty
To understand why Convair was prepared to take on such a challenge, you must realize what it was competing against. The Boeing 707 and the Douglas DC8 were the first American built commercial jetliners. Moreover, virtually overnight, they transformed the way people traveled with their larger size, higher efficiency, and increased range. Additionally, at the same time, they were making huge profits.
Seating inside a Swiss Air Convair 990. Photo: James Petts via Flickr
The two big boys were not alone with Convair introducing the 880 after having success with propeller-driven planes and military aircraft. The 880 looked very similar to the 707 and DC8. However, Convair went after a different market segment touting the 880 as being a faster, more luxurious medium-range jet. While this market existed, it was minuscule compared to the market Boeing and Douglas were after.
Convair was convinced it could build a plane capable of cruising at 635 mph
Even before the first 880 rolled off the production line in San Diego, Convair knew it was destined to fail. While orders for the Boeing 707 and DC8 started to fill the books, Convair struggled to sell its smaller jet.
Having spent millions in the 880s development, Convair jumped at the opportunity when American Airlines asked for a fast airliner. the firm was convinced that it would be able to make the 880 larger and faster despite Boeing’s misgivings.
American Airlines wanted a faster plane for transcontinental flights. Photo: San Diego Air and Space Museum Archive via Flickr
Boeing engineers already knew that the 707 was at or near the limit of subsonic speed. Therefore, it did not want to push the envelope further. Before subsonic becomes sonic, you must first pass through what is known as transonic.
This is a speed regime which dramatically increases the drag on an aircraft. With increased drag comes less efficiency and a loss of range. Therefore, Convair needed to put its thinking cap on. The new plane would not only need to be fast; it would also have to be able to fly further than the 880.
For this to happen, the 990 was given more powerful engines by adding a separate fan system into the engine’s exhaust. This move created the world’s first turbofan airliner. To counter transonic drag, the aircraft had a new 39 degree swept wing and large anti-shock bodies that would be used for additional fuel storage.
Flaws started to appear
On paper, it appeared as though Convair had designed the world’s fastest airliner.
When the 990 first took to the skies in January of 1961, problems started to appear with the plane unable to cruise at 635mph. This was due to turbulence around the inboard engines that interfered with the effectiveness of the elevators.
Together with this, numerous flaws started to appear with excessive drag occurring in all areas all around the aircraft. As Convair was busy trying to resolve the plane’s problems, American Airlines were desperate for aircraft, calling the company back to the negotiating table to reduce its order.
Additionally, the airline said that the first 15 of its order did not need to fly at 635 mph. The remaining five aircraft would still need to be fast but with a lower speed of 620mph. Convair, however, did not give up on its promise producing the 990A, which was capable of meeting the speed it had initially promised.
The Convair 990 was the worlds fastest airliner
While Convair had now built the world’s fastest airliner, it did not matter so much. Altogether, Boeing and Douglas had established themselves as the major players. After losing half a billion dollars in the development of the 880 and 990, it turned out that the plane’s speed and comfort were not enough.
Airlines wanted a fuel-efficient long-range capable jet that could carry hundreds of passengers thousands of miles. Following the disaster of the Convair commercial airliner program, the company never produced another civilian passenger plane. Despite this, the 880 and especially the 990 went on to earn legendary status. This was partly because they were rare and not in operation long.
The Convair 990 was the end of an era
A bit like what we are seeing with the Airbus A340 today, the oil crisis in the early 1970s had airlines desperate to get rid of their gas-guzzling Convairs. These jets effectively marked the end of an era when flying was restricted mainly to the wealthy and when airlines were more interested in speed than efficiency.
Swiss Air was the only airline to dub the 990 the “Coronado.” Photo: San Diego Air & Space Museum Archives via Wikimedia
The Convair 990 assembly line shut down in 1963, with only 37 aircraft built. American Airlines and Swiss Air were the primary purchasers of these planes. TWA and Delta Air Lines meanwhile operated the smaller 880 version. Swiss Air purchased eight 990s and was the only airline to call it “Coronado.”
Perhaps the most successful bespoke plane
Share this article: