Wednesday, September 26, 2018

The stubby, short-lived 747SP

As I've been melancholically following the gradual demise of the Boeing 747 (see here and here and here), I've been meaning to write about an fascinating variant of the original Jumbo Jet: the 747SP. The SP (for "Special Performance") was a shorter, longer-range version of the original 747; the story behind it is extremely interesting.
The 747SP is a brief, and largely forgotten page in the 747's proud history.  Not many books or articles have been written about this fascinating aircraft, largely because it never realized the commercial success of its larger siblings.  This stubby 747 model was by many measures a commercial failure, with Boeing only managing to sell 45 during the aircraft's eight year production run from 1976 to 1982, 1987.  The line did reopen again briefly in 1987 so that Boeing could produce one final aircraft.
Yet despite its lackluster sales the aircraft filled a very important niche market for Boeing at the time and pioneered the concept of ultra long range flights, paving the way for the 400 series that followed.  The SP's exceptional performance and long range opened up new routes, making nonstop flights between city pairs like Sydney-Los Angeles, Johannesburg-London and New York-Tokyo a practical reality for the first time. The 747SP over the course of its airline career set many performance benchmarks for its class including the fastest round the world flight from pole to pole.  Unfortunately the airplane never truly found widespread acceptance in the market outside of its ultra long range niche.  So just how did this curious aircraft come to be and what were the market factors that led Boeing to design this unusual aircraft in the first place?
The first Boeing 747 entered service in 1970; however, within a couple of years McDonnell Douglas and Lockheed were offering wide-body aircraft of their own - the DC-10 and L-1011, respectively - and Boeing realized it was at a competitive disadvantage.
Meanwhile in Seattle Boeing had been closely following the development of the DC-10 and L-1011 and soon realized that the new tri-jets exposed a large hole in the company's product line between the aging 169 seat 707-300 and the much larger 380 seat 747-200B.  Boeing had no effective product in the long range, mid capacity segment of the market. The DC-10 and L-1011 had carved out a niche that was costing Boeing potential customers.  Not only were new customers flocking to order the new tri-jets but existing 747 operators were placing orders as well.  The initial models of both the L-1011 and DC-10 didn't have intercontinental reach but both manufactures were hard at work developing long range derivatives which would hit the market in a few short years. 
Since the late 1960's Boeing had been studying various concepts involving shortened and modified two and three engine 747 designs to match the capacity requirements of the DC-10 and L-1011 proposals.  The major problem with any four engine 747 derivative was overcoming the 33% fuel burn deficit a four engine airplane would have when compared to a three engine jet.  Very simply the more engines an aircraft has the heavier the airplane is, the more fuel it burns and correspondingly the more costly it is for an airline to fly and maintain.
However, a two- or three-engined version of the 747 would have required so much redesign that it would have been, essentially, a completely different aircraft.
No one in Everett was interested in building an all new aircraft.  That would simply take too much time and cost too much money to develop and would place Boeing well behind Lockheed and McDonnell-Douglas in the market. Boeing didn't have six or seven years to launch a competitive answer they need something that could be built cheaply and be brought to market quickly.  Eventually led by Joe Sutter, the father of the 747, it was agreed that the best course of action was to shorten the existing 747 fuselage and retain the aircraft's existing wing and four engine arrangement.  Sutter reasoned that while the shortened 747 might not be able to match the DC-10 or L-1011's fuel burn or operating costs it would retain commonality with existing 747's which would reduce manufacturing and production costs for the company.  The parts and systems commonality with existing 747's would also save current 747 operators considerable money in training and maintenance expenses and this just might be enough to sway them from purchasing the DC-10 or L-1011.
With a concept in place Boeing set about optimizing and tweaking the design of the 747SB or "Short Body" as it was then called.  The existing 747 fuselage was shortened by 48 feet to accommodate around 280 passengers in a two class arrangement which closely matched the competing DC-10 and L-1011's capacity and placed it 100 seats under the existing 747-200B. The new aircraft retained the standard 747 wing, in combination with a 2 ft. taller tail and 10 ft. longer horizontal stabilizer span.  The shortened aircraft, with its reduced structure and components enabled Boeing to lighten the airplane's gross weight by 125,000 lbs when compared to the standard 747 air frame.   
A lighter airplane led to a 20% reduction in fuel burn, which in combination with the 747's speed and the projected 4,000-6,000 foot higher cruise altitude gave it the exceptional capability to fly 270 passengers and cargo almost 7,000 miles!  A distance well beyond the reach of the DC-10 or L-1011.  The aircraft's performance if it penciled out would give it the lowest seat mile costs of any aircraft of its size class, besting both its tri-jet competitors.
Despite the aircraft's promise on paper the Boeing board was not entirely convinced of its commercial potential, giving the project only incremental approval in June, 1973.  Around that same time Pan Am issued a firm requirement for an aircraft to deploy on long range routes with demand too thin to support a full size 747.  Both Lockheed and McDonnell-Douglas pitched long range derivatives of the DC-10 and L-1011. 
To highlight the new 747's performance advantage over the competition Boeing re-designated the aircraft as the 747SP for Special Performance.  Two months later in August of 1973 the Boeing board formally approved the aircraft launch, believing that a launch order from Pan Am was inevitable.  The company took a substantial risk by green lighting the SP before receiving a minimum order commitment, but by this time most inside the company had been won over by the SP's impressive economics.  Furthermore Joe Sutter had thrown his full support behind the project and that was enough to convince most skeptics that the aircraft would be embraced by airline customers around the world. 
The SP entered service with Pan Am three years later, in April of 1976. Pan Am would eventually purchase 10 of the aircraft. The second launch customer, South African Airways, would purchase 6. The 747SP's range was especially useful for SAA because other African nations would not grant airspace to the Apartheid government's flag carrier, meaning that the airline was forced to fly longer, more circuitous routes around the continent (SAA 747SPs even briefly served Houston, before anti-Apartheid legislation prevented South African Airways from flying to the United States at all).

Pan Am and SAA were both pleased with the aircraft, and Boeing hoped to sell 200 of them. However, in spite of the SP's impressive range and performance, Boeing never made it past the model's break-even point of 45 aircraft. It turned out the the 747SP was simply too much of a "niche" aircraft; most carriers just didn't have a network full of long-range routes suited to the 747SP's specifications and were looking for wide-body aircraft with more flexibility.
Despite all of the data and statistics that validated the superiority of Boeing's 747SP the DC-10  proved a tough competitor to best.  Unlike the 747SP which had been specifically designed and optimized for very long range routes with limited demand, the DC-10 platform had been designed from the outset with flexibility in mind.  McDonnell-Douglas was able to optimize the aircraft to a variety of routes and mission requirements. The short range 10 series was an ideal aircraft for U.S. domestic trunk routes for airlines like United and American.  While the longer range 30 series had the endurance to fly trans-oceanic routes as well as intercontinental flights between Africa, Asia and Europe.  In all McDonnell-Douglas produced 446 aircraft across 9 different variants of the DC-10 through out its 18 year production run from 1971 to 1989.
It didn't help that the 747SP's $28 million price tag was a full $1.5 million more than that of the DC-10. The advent of the twin-engined Airbus A300, as well as the ETOPS program allowing twin-engined aircraft to fly longer distances over water, further put the 747SP at a disadvantage, and Boeing pulled the plug on the program in the early 1980s.

The 747SP's production might have been short-lived, but was it a failure?
It is easy to say given the 747SP's less than stellar sales that it was a failure, after all both McDonnell-Douglas and Lockheed sold far more trj-jets.  But from a cost perspective the derivative aircraft was relatively cheap for Boeing to design and build and it ended up just about breaking even for the company. The SP also allowed Boeing to retain key 747 customers and thwarted a number of potential sales of the DC-10 and L-1011.  
For the small niche market that the aircraft was designed and built for there was no equal. You either had to buy a 747SP or lose high yield customers to your competitor who could get there faster and nonstop. Ultimately neither the DC-10 or L-1011 came close to matching the 747SP's incredible top end range and payload uplift.
The 747SP has long since been removed from commercial service. There are still, however, ten of these unique aircraft currently in active service. Most are used as VIP transports, but Pratt and Whitney Canada uses two of them as flying testbeds and one of them is used by NASA as the flying observatory SOFIA. The 747SP also remains popular among aviation enthusiasts. There is an entire website and a Facebook page devoted to the airplane.

It's also worth noting that the 747SP has a better survival record than one of its competitors, the Lockheed L-1011. 250 of the iconic three-engined aircraft were built, but only two are currently airworthy. Dozens of DC-10s (and its successor MD-11s), meanwhile, are still in active service as freighters with companies such as UPS and FedEx.

In the passenger realm, however, these aircraft have long since been superseded by twin-engined aircraft such as the Boeing 777 and 787 or the Airbus A330 and A350. Case in point: while the 747SP's 7,000-mile range was impressive for its time and made the concept of ultra-long-haul routes viable, Singapore Airlines just took delivery of its first Airbus A350-900ULR. This airplane has a range of about 11,000 miles and which will be put to use on a 9,500-mile, 19-hour flight between Singapore and New York-Newark.

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