I researched but all I could find was that the KC-135s were initially the "Boeing 717s" originally (Model 717). What I couldn't find is why exactly Boeing decided to not call them 717s in the end.

Apologies if this has been asked/answered before, but I really couldn't find anything. All I could find was just that the KC-135s were originally called 717s.

Thanks

Surely KC-135 is just the USAF designation for them?

Bhoy wrote:

Surely KC-135 is just the USAF designation for them?

This is correct

Boeing didn't decide to call them KC-135, the Air Force did. The US military has their own designations for aircraft that are completely separate from what their manufacturers call them. At Boeing I believe it was always the 717 internally; that's just not what the public knows them as. Since the 717/KC-135 had been out of production for decades I believe that was why they were able to reuse that model number on what was formerly the MD-95.

Bhoy wrote:

Surely KC-135 is just the USAF designation for them?

It's also the Military designation for the 707, not the 717.

Ah, apologies!

So would it be accurate to call the KC-135s as 717-100s?

The marketing department decided that "Model 700" did not have a good ring to it for the company's first commercial jet. So they decided to skip ahead to Model 707 because that reiteration seemed a bit catchier. Following that pattern, the other offspring of the Dash 80, the Air Force tanker, was given the model number 717. Since it was an Air Force plane, it was also given a military designation of KC-135.

The KC-135 was never sold as a commercial plane, so only the military designation KC-135 is needed.

https://www.boeing.com/news/frontiers/archive/2004/february/i_history.html

citationjet wrote:

The marketing department decided that "Model 700" did not have a good ring to it for the company's first commercial jet. So they decided to skip ahead to Model 707 because that reiteration seemed a bit catchier. Following that pattern, the other offspring of the Dash 80, the Air Force tanker, was given the model number 717. Since it was an Air Force plane, it was also given a military designation of KC-135.

The KC-135 was never sold as a commercial plane, so only the military designation KC-135 is needed.

https://www.boeing.com/news/frontiers/archive/2004/february/i_history.html

According to that article..

"Air Force tanker, was given the model number 717. Since it was an Air Force plane, it was also given a military designation of KC-135."

So it is still technically accurate to call the KC-135s as Boeing 717s. Quite a neat thing I've learned today! Thanks for linking this.

Veigar wrote:

So would it be accurate to call the KC-135s as 717-100s?

Maybe technically it would be accurate, but it would cause confusion, because it was reused later. After the Boeing-McDonnell Douglas merger in the late 1990s, the model number 717 was reused to identify the MD-95 as part of the Boeing commercial jet family. Most people associate the 717 with the twin engine commercial product.

Perhaps it explains why the MD-95 became the 717-*200*!

Also, thanks to whoever moved this topic. Still a bit of a noob to this forum.

vtchaz78 wrote:

Bhoy wrote:

Surely KC-135 is just the USAF designation for them?

It's also the Military designation for the 707, not the 717.

Wrong, the 707 is a 6 abreast aircraft while the 717/KC135, while having a similar appearance, is a 5 abreast aircraft (if fitted with seats).

And both the 707 and 717 are wider than the 367-80 (aka 707 prototype).

There is also the Boeing 739 (RC135), which is based off the 717.

The non tanker version is a C-135

Veigar wrote:

Perhaps it explains why the MD-95 became the 717-*200*!

Not necessarily. The -100 designation was used early on, but eventually got dropped, with more recent models starting at -200. The 707, 727, and 747 all have -100 variants, but the 757, 767, and 777 (and later still the 717) started at -200. Obviously the 787 took an entirely different approach, starting with the -8 (and a proposed -3 which never came to be built).

vtchaz78 wrote:

Bhoy wrote:

Surely KC-135 is just the USAF designation for them?

It's also the Military designation for the 707, not the 717.

No, the Boeing model 717 (Original Recipe) is the C-135 (KC/EC/RC etc.) The Boeing 707 has the USAF designation of C-137, one notable example being the VC-137 used for Air Force 1 duties for many years.

dgbinpc wrote:

The non tanker version is a C-135

To be totally Aviation nerdy: the Boeing 717 is in US military uniform the C-135. It has a narrower fuselage and is shorter than the 707.

It has a number of different variants for different missions, the tanker derivative is one of them:
Boeing C-135 Stratolifter
Boeing KC-135 Stratotanker
Boeing EC-135
Boeing NC-135
Boeing RC-135
OC-135B Open Skies
WC-135 Constant Phoenix

The Boeing 707 also has many variants in [ US ] military service:
Boeing CC-137
Boeing E-3 Sentry
Boeing E-6 Mercury
Northrop Grumman E-8 Joint STARS
VC-137C SAM 26000 / SAM 27000 (Air Force One)
CT-49A (NATO crew trainer)
CC-137 Husky
KC-137 Brazilian Air Force
707T/T (Italian Air Force, refueling a/c)
KE-3A (Saudi Airforce, refueling a/c)
Condor (Airborne Early Warning, Command and Control, IAI development)

Dutchy wrote:

dgbinpc wrote:

The non tanker version is a C-135

To be totally Aviation nerdy: the Boeing 717 is in US military uniform the C-135. It has a narrower fuselage and is shorter than the 707.

It has a number of different variants for different missions, the tanker derivative is one of them:
Boeing C-135 Stratolifter
Boeing KC-135 Stratotanker
Boeing EC-135
Boeing NC-135
Boeing RC-135
OC-135B Open Skies
WC-135 Constant Phoenix

The Boeing 707 also has many variants in [ US ] military service:
Boeing CC-137
Boeing E-3 Sentry
Boeing E-6 Mercury
Northrop Grumman E-8 Joint STARS
VC-137C SAM 26000 / SAM 27000 (Air Force One)
CT-49A (NATO crew trainer)
CC-137 Husky
KC-137 Brazilian Air Force
707T/T (Italian Air Force, refueling a/c)
KE-3A (Saudi Airforce, refueling a/c)
Condor (Airborne Early Warning, Command and Control, IAI development)

There was also the USAF TC-18 as well, used for pilot training instead of risking someone pranging a nice E-3

Spacepope wrote:

There was also the USAF TC-18 as well, used for pilot training instead of risking someone pranging a nice E-3

And don’t forget C-18A & EC-18B.... C-18 variants were all based on the 707-320

Spacepope wrote:

There was also the USAF TC-18 as well, used for pilot training instead of risking someone pranging a nice E-3

Forgot about the C-18. Why did NATO call them CT-49A as there was a USAF destination of TC-18, or should they be called: TE-3?

Veigar wrote:

Ah, apologies!

So would it be accurate to call the KC-135s as 717-100s?

Yes, specifically 717-148, with "48" representing one of several USAF "customer codes", although in this case those digits (48) were also used at one time for Aer Lingus.

Click on all three of these data base photos (one at a time!), so that you can read the full description for each.
On the left; a Boeing KC-135R Stratotanker (717-148)
In the middle, a Boeing VC-137B (707-153B)
On the right; a Boeing 717-231

Or just do your own photo search for "Boeing 717" and watch how many KC-135s turn up.

Heritage/configuration-wise the KC-135 [717] and the B720 are as close as they come.

Primary difference is obvious interior configuration, mission and engines [-135 started life with J-57s turbojet engines and the 720 went straight to the early JT3D fan engine].

NOTE. The 767 tanker adopted by early FMS customers is the KC767A... which is distinctly different from the USAF configuration tanker... KC-46A.

Boeing "names" or numbers were originally entirely sequential starting with number 1. Few will remember the Boeing 200 Monomail mail plane which was later converted into Boeing 221, an eight passenger airliner. Better known is Boeing 247, sort of DC-3 clone.

Boeing 299 is best known as the B-17 bomber. The B-52 bomber went through many Boeing numbers until Boeing number 454 was finally approved by the Air Force.

Shortly after the war Pan Am was in talks with Boeing about a jet powered airliner. Basis of the talks happened to be the military transport plane C-97, as the Air Force was also whishing a pure jet powered KC-97 for its B-47 bomber. The C-97 happened to be Boeing number 367. It wasn't easy. Many proposals later it became apparent that it would be a clean sheet design based very little on the 367, which itself was based on the B-29 (B-50) bomber. But the 80th proposal was approved to be built and tested, therefore the prototype became 367-80.

Pan Am had - as a stop gap - to get more modern airliners before a jet plane could be ready. A much updated C-97 or 367 became the 377 Stratocruiser.

Now at some time roughly 70 years ago Boeing planned to widen their business, and they decided to name their products in blocks of 100 according to product category. 3xx and 4xx would continue to be "normal" aircraft, while 5xx would be turbine engines, and 6xx would be rocket engines and missiles. And then jet transport planes would be 7xx.

Now the 367-80 gets ready for first flight, and gets the FAA registration N70700. We can guess that 70700 is no coincidence. But some people around it called it the 707 (others called it Dash-80). Maybe because they read 70700 as 707 dollars and zero cent? In any case, what should have been the 700, if the rules had been followed, became the 707. It may have influenced that the digit 7 was present in several earlier successful Boeing designs such as 247, 307, 367 (C-97) and 377.

WKTaylor wrote:

Heritage/configuration-wise the KC-135 [717] and the B720 are as close as they come.

Primary difference is obvious interior configuration, mission and engines [-135 started life with J-57s turbojet engines and the 720 went straight to the early JT3D fan engine].

No. 65 first 720 were made with JT3C (J57) engines. 10 of them (American Airlines) were later converted to JT3D. 89 were built new with JT3D fan engines, named 720B.

Four 720 non-B with JT3C engines flew here in Denmark with charter airline Conair of Scandinavia in the early 70'es - ex UA planes. They were replaced with five 720B planes, also ex UA.

The old 720s with the weak JT3C engines were often quite troublesome as many charter destinations at that time didn't have 10,000+ ft runways. So back home from sunny places it was zig-zagging to fueling stops.

prebennorholm... DANG... Good history lesson!

The 'JT3' led me assume fan engine... Never realized JT3C was a TJE that evolved to the JT3D TFE.