KC-135 / C-135
 

I'm seeking opinions about a small disagreement we are having regarding the previous NASA 'Vomit Comet' aircraft.

These aircraft were originally manufactured as KC-135A tankers but later had the refueling capability removed to support the 'reduced gravity' training operations for the Apollo astronauts.

I maintain that with the removal of the tanking capability, under the US military designation system, the aircraft became C-135As - or perhaps NKC-135As - but others say it is still KC-135.

I know this is such a minor point but interested to hear opinions.

NASA refers to it as a KC-135.

https://www.nasa.gov/vision/space/pr...35onfinal.html

NASA always referred to them as KC-135s, and their FAA registrations were as KC-135As
https://registry.faa.gov/aircraftinq...mbertxt=N931NA

Being pseudo-civillian aircraft, they would possibly be outside the US Mil designation system

The NASA "Vomit Comet" was a KC-135A - 5 different aircraft were used - 1967 to 2004 - replaced by the C-9.

The NC-135As and NKC-135A were various test aircraft for EW, reconnaissance systems, airborne laser lab etc
https://en.wikipedia.org/wiki/Boeing_NC-135

And I always thought they were Comets :O

Absolutely I know that NASA et al refer to it as a KC-135A, and perhaps saying it is pseudo civilian removes the requirements from changing it from a KC-135 to a C-135 but then why not call it a Boeing Model 717? And other KC-135As were modified and received new designations (e.g. EC-135 and RC-135).

I still believe that the 'Modified Mission' prefix should be removed once the tanking capability had been removed.

I suspect that not all EC- and RC-135's were previously KC-135's, they may have started life as C-135's.

A lot did. I'm reading 'Boeing KC-135 Stratotanker- More Than A Tanker' at the moment and the modification/conversion history of some of those aircraft is quite convoluted.

I take comfort that I am not the only one who has pondered the nuances of the KC/C/RC/EC/NKC/ARIA/WC-135 family and designations....and that's not even counting the E-3, E-6, E-8.....

The E-3, E-6 etc. are all based on the 707 rather than the 135 series and the fuselages are 4" wider, 148" not 144".

The original Dash 80 fuselage was only 132" wide, unfortunately when Mr. Boeing went on to build the 135, 707, 727, 737 etc he kept the original Dash 80 nose section dimensions which is why it is so cramped up front.

evilroy, what I managed to find on the book shelf re aircraft used for the "Vomit" flights, you'll note that four were KC's with a lone C. Only 15 C-135A were built (Boeing 717-157) against 732 KC-135A (a mix of 29 717-100A, 68 717-146, 635 717-148). Essentially the C was a KC that had the flight refueling gear removed but still had the boomers station, the other engineering change that prompted the different designation was the beefed up floor and cargo retention points.

55-3129 (Weightless Wonder) KC-135A 1968 converted to NKC-135A testing on board avionics, later winglet tests, 1982 reengined with TF33, 1984 converted to EC-135P for the Commander in Chief Atlantic Forces

62-3536 (weightless Wonder II) KC-135A Zero G 1967-70 converted to EC-135K May 1970 W/O Sep 1977 Crashed in steep terrain during a night time climb out of Kirtland Air Force Base. The aircraft struck a peak in the Manzano Mountains, about 10 meters below the summit. 20 fatal

60-0378 C-135A (Weightless Wonder III) with NASA 07.68-05.73, 11795 parabolas in 1120 hrs, converted to VC-135A late 75

59-1481 (weightless Wonder IV) KC-135A flew more than 58,000 parabolas 1973 - 1995

63-7998 (Weightless Wonder V) KC-135A also used to film weightless scenes in Apollo 13 movie

A full listing of variants and their uses can be found at http://www.uswarplanes.net/kc135.html

"I still believe that the 'Modified Mission' prefix should be removed once the tanking capability had been removed"

You do - they don't :(

as they own and operate the aeroplanes I think that's the end of story

Neither the military nor NASA are in the slightest bit interested in oddities of nomenclature and neither should they be

You can open the SR-71 or F-117 cans of worms if you really like

Perhaps you have the authoritative data. I am surprised that the C- started as a KC- and had refueling gear actually removed. Maybe so. My understanding was that the immediate need for jet transport aircraft, before the C-141 was entered into service, led to the decision to build the C- variant of the KC-, and I would have expected that it to have been built without the refueling gear at all. It may be a false assumption. Having about 1,000 hours in the C-135, out-fitted as a VIP Special Missions transport, I don't recall any mention, ever, of a residual "boomer's station" and certainly no visual sign of it externally. One advantage that the VC-135 had over the VC-137 (modified B707) was extremely long range, and another, for the flight crew, was the spacious flight deck.

And if they were being pedantic, should have been C-137 variants (The E3 originally was EC-137D,) along with the C-18.

Many of the E series were 707's, in as much they are converted ex airline aircraft, E-8C 90-0175 being ex QANTAS for example.The US changed the designation system in 1962, any 707 delivered after that date changed from C-137 to C-18

You and me both. The 135 fleet is largely unsung, but they must be some of the busiest in the US inventory. A casual glance at any of ADS-B sites will reveal all manner of REACH flights etc etc out and about at any one time.

Not strictly true, VC-137 72-27000 was delivered 10 years after that, and a further two C-137s were obtained second hand in the 80s. They adopted C-18 for the second hand 320 series airframes they purchased. If you were strictly following the 'rules' as these were all variants of the original C-137 they should have had C-137 derived designations but there are logical reasons for not doing so. (Upgrade status, fleet management, avoiding confusion!). Same thing goes for the various 737 and 747 military versions, there would be no logic in the Posideon being the PT-43H

What it does show is that the system doesn't always follow strict rules, so even a chang in role may not result in anoevrall change of designation

I saw a NKC-137 (can't remember the suffix) on the line at Miramar in 1995, confusion reigns.

Dave, I wonder if the 1962 change didn't apply to those aircraft because of the use to which they were put, VIP transportation, particularly President and Vice President etc. All went to the 89th Military Airlift Wing which took over from the 1254th ATW in 1966. Logic to me to have the aircraft assigned the same designation for maintenance purposes if nothing else, since except for the two EC, all aircraft were operated by the one unit supplying VIP transportation. There is always an outlier in these things, or "what about". The designation covered nine aircraft

VC-137A 58-6970, 58-6971, 58-6972, re-deseginated VC-137B after re-engining, C-137B following removal from VIP role
VC-137C 62-6000, 72-7000 Presidential aircraft, C-137C when Presidential role removed
C-137C 85-6973, 85-6974 second hand, one ex Buffalo Airways, one that had been seized buy US Customs, one airframe later becoming an E-8C
EC-137D two airframes built as Early Warning and Control System prototypes. Later re-engined and re-designated E-3A.

Thanks, they were fairly common visitors at Heathrow in the 70s/80s and I was trying to recall yesterday if they were VC-135s or VC-137s.

Looking at ADSB, some of the RC-135s visiting the UK have interesting designations and missions, one I noticed recently was an RC-135S Cobra Ball - can't recall if it was an overflight or heading into Mildenhall.