Part of 6 B-707 articles series
Rafiq Jan
Variants and derivatives of 707 family
Major variants of B707 were; Boeing 720, Boeing C-137 Stratoliner, Boeing E-3 Sentry, Boeing E-6 Mercury, Northrop Grumman E-8 Joint STARS.
Different models
Boeing 707-120
Boeing 707-120B
Boeing 707-320
Boeing 707-320B
Boeing 707-420
Boeing 707-320C
Boeing 707-379C
Boeing 720
Boeing 707-436. This series had the option of Rolls Royce Conway Turbojet engines.
Boeing 707 with the letter “C” on its type was a designator for its convertibility from passenger to freighter use. It had a big built-in main deck cargo door already incorporated during its production process to give flexibility to the operators for conversion between passenger and freighter.
Military specific versions of Boeing 707
Boeing 707 had this unique status of the only commercial jetliner that was adapted to many different versions of the military, navy, air force, and many other special uses like research and special pieces of training. The birth of Boeing 707s was indeed the tipping point in the unstoppable progress of the U.S plane-making brand called the Boeing company.
The legendary 707 may be all but gone and dead, but the KC-135 will be with us for a while longer. The U.S.A.F wants to keep the KC-135 flying for the next 100 years. A credit that no other plane earned in the history of aviation.
Accidents and Hull-Losses
Boeing 707 has been involved in 261 occurrences out of which 174 Hull-losses with over 3000 casualties. But compared to its rivals, it was regarded as the safest jetliner of its time by aviation safety experts. Not only a favorite of travelers, but it was loved by the pilots too, due to her better handling and flying prowess.
The downsides
Despite a huge number of design innovations, it had few downsides too. But given the drastic development in air travel that it brought, all those drawbacks were of not much significance to the operators. Its popularity had already won the hearts of nations across the globe.
Extremely noisy engines at takeoff thrust.
It had many deadly crashes, most of them with no survivors.
Prodigious fuel guzzler jet engine airplane of its time. Four engines with high fuel consumption were still not biting the operators due to their monopoly in the market. There were hardly any competitors to this already dominant turbo-jetliner that won the hearts of the head of the states at its very launch. Hence this millstone of 60z successfully reigned the skies of the entire globe more than others for almost two decades.
Environmentally unfriendly engines.
The early series of 707 with JT-3C turbojet engines used water injection at take-off thrust to enhance the thrust at take-off on shorter runways and hot OAT airports. But it had its downsides despite the power augmentation. It had added weight that was compromised on load-carrying capacity. Moreover, the water injection operation at take-off power generated a characteristic black smoke and gases which was an environmental hazard.
This system was eliminated in the later versions of JT-3D engines.
End of part 5
The author is Aircraft Engineer, Author & Planes enthusiast
