Boeing 707 transition from turbojet to turbofan

[b377]

While I'm sure this topic may have been discussed before can anyone advise if the JT3C turbo-jet to JT3D turbo-fan 707 upgrades were mandatory or descretionary? (the fan's merit being of course lower polution & noise, higher power & efficiency)

Why? Becuase considering that the intoduction of the fan engine was quite early in the 707s career (early 60s) whence all new 707s were pressumably fitted with the better fans, the jet powered 707 remained in service well into the late 70s maybe even 80s. Were those original engines upgraded to see service in parallel with the fan?

The JT3C nacelle and exhaust nozzlse being very distinctive (easy to confuse with the RR Conway, even though the Conway was a fan) and arguably nicer to regard than the later P&W fan version. Photo from 1972 but these engines are seen into late 70s.http://cdn-www.airliners.net/aviation-photos/photos/4/5/5/1278554.jpg

[BelArgUSA]

Hola b377 -
xxx
Doing this from memory.
The JT3D versions appeared quite early in the 707-720 production history.
Quite a few old "straight pipe" JT3C powered were reengined with JT3D.
xxx
If I recall well, American Airlines reengined they entire 707-123 and 720-023 fleet.
These were "converted engines", installing the fan on the core JT3C-6 and 7.
The engine designation became JT3D-1-MC6 or MC7 (MC= Major Change).
These were both 17,000 lbs/thrust engines.
I think TWA converted some 707-131 airplanes. Cannot recall.
Qantas converted all their 707-138 to fans. Travolta's is one of these.
Western Airlines 720-047 all got (I think) converted.
I cannot recall what happened with Northwest and Continental.
xxx
However, quite a few "straight pipe" 707-100 remained with original engines.
United and Aer Lingus 720 remained with their original JT3C-7.
They were first to be retired in the early 1970s.
I do not recall, nor can document any 707-300/400 converted to fans.
They kept their JT4A/Conways for their entire flying history.
The 707-100B and 707-300B started to be delivered in 1961 or 1962.
Most 707-100B had JT3D-1, and 300 were JT3D-3B (or later even -7)
xxx
You better look on the 707-720 production list for accurate details.
Gave all my 707/720 books to wannabees... so cannot help any further.
xxx
:ok:
Happy contrails

P.S.
Sure, the Conways were fans... but the bypass ratio quite low.
Just like the 727-737-DC9 JT8D... I would call them "bypass" instead.

[b377]

Thanks for that !

I pressume the converted -3C engines also got the new fan nacelle?

Ok, so which type were those noisy, smokey jet engines one sees in early DC8 & 707 pics? Was the -3C jet a later cleaner version of the launch engine?

Quite right the Brits do use the term by-pass, it was P&W who introduced the 'fan' adjective for the -3D .

[WHBM]

Hola BelArg (and others)

Continental only bought five of the early 707-124 model. Two of the five were lost by the mid-1960s and the other three were sold in 1967 to TWA. Then Continental came back and bought many of the fan-engined models.

Western only bought two of the early models (originally ordered by Cubana but embargoed before delivery), which they sold on in 1962 to Pan Am, who lost one of them shortly afterwards and converted the other to fan engines. Western then, again, bough many of the later fan-engined models from new. To be precise there was never any 720-047, only 720-047B.

TWA never converted any of their substantial early fleet of the old "straight pipe" 707s, in fact they later bought Continental's fleet, and ran them all on until the early 1970s.

American converted a huge number of both 707s and 720s, some after less than 12 months service.

Northwest never had a straight pipe Boeing, though they again built up a large fan-powered fleet later. Reason for this was that Northwest were originally a DC8 customer (little-remembered nowadays), they bought five DC8-30s (straight pipe in themselves) and operated them to Asia for a few years, and had another five DC8-50s on order, then cancelled the order, sold the older DC8s to National, and changed completely over to Boeing.

United and Eastern both kept their old 720s as they were until retirement.

The Aer Lingus pair didn't do a lot of work once they bought their first 707-320Cs in the mid-60s, they were leased out a lot and I remember seeing one substituting for an Aer Lingus Viscount from Dublin into Bristol, of all places, which must have been hugely unprofitable.

It is correct that no 707-320 was converted to fan engines whereas many of the 707-120 and 720 were. Must have been some good reason for that, I have always suspected that Boeing did not want to offer such a conversion because they figured it was more profitable to Boeing to require operators to buy whole new aircraft, once they saw how extensive a programme American did.

If you want a complete detailed list, it's here :

http://www.planelist.net/boeing-707.zip

(you'll need WinZip to unzip the file)

[BelArgUSA]

The original 707-121 were powered by JT3C-6 - (Water Injection)
The original 720-022 were powered by JT3C-7 - (NO Water Injection)
The original 707-227 were powered by JT4A-3
The original 707-321 were powered by JT4A-9
The original 707-436 were powered by R.Co.12
xxx
The airplanes equipped with fans JT3D all had the same fan cowlings.
One variation - small cowl doors JT3D-1, some JT3D-3B
Large cowl doors on JT3D-3B (most had that option) and JT3D-7
xxx
T/C inlet on top of engine nº 2, 3 and 4 for all 707s.
T/C inlet only on top of engine nº 2 and 3 for all 720s.
Exception: American 707-100/300 only had T/C on nº 2 and 3.
Some of American 707-300 had T/C cowl on nº 4, but T/C NOT installed.
xxx
Smoke on takeoff - the worst were JT3C especially with water injection used.
The runway went below RVR minimums for the next 10 minutes.
xxx
:ok:
Happy contrails

[b377]

What engine would you then say the AF plane above ( in service until late 70s at least) has ,JT4A?

I pressume all -3C engines were the first to be replaced by fans due to the pollution ...

I would love to hear again and compare the sound of -3C, -4A, -3D fitted planes on take off. I do remember the early 707 engines producing a penetrating high pitch whine even in idle something late engines did not have.

RR Darts such as on the Viscount & Andover were never quietened still have that loud whine.

[WHBM]

Air France only had 707-328 of the early models, therefore (according to BelArg's list) JT4A-9.

F-BHSC, the aircraft in the pic, was the 82nd 707 off the line and delivered to Air France in December 1959. It was sold to the Israeli Air Force in 1978 and ultimately scrapped in the early 1990s.

[b377]

An early water injected dc8 ...

http://www.boeing.com/companyoffices/gallery/images/commercial/dc8-05.jpg

[BelArgUSA]

Hola b377 -
xxx
As to which engines on that AF -328, in 1972, it would certainly have the latest dash number (JT4A-11) at that time, these had 17,500 lbs of thrust each, and the maximum gross weight was up to 312,000 lbs. They were guzzlers, but had adequate power. Funny is, their performance was great at higher levels above FL350, whereas the JT3D fans "ran out" of vitamins and ideas above FL350.
xxx
With PanAm, I recall we had fuel flows in cruise close to 16,000 lbs/hr for the 707-321/331, while the 707-321B fuel flows dropped below 13,000 lbs/hr. To my opinion, the 321B were better airplanes especially on takeoff, thanks to their better flaps settings and leading edge devices.
xxx
The 707-100 and 720s, with their JT3C were merely converting fuel into noise and smoke. I never flew the "Water Wagons", I recall that pilots telling me flying them for a "wet takeoff" hated their handling when the water injection quit after takeoff at "uneven times"... making the pilot believe that they had an engine "failure" on the left side, then a few seconds later, on the right side, this repeatedly until the water tanks were all empty.
xxx
All pilots loved the 720B... the race horse, even taking off from La Paz, Bolivia. PanAm inherited some ex-Lufty 720-030B, but did not keep them long in operations.
xxx
Thank you b377, for forcing my old brains to recall these great planes.
:}
Happy contrails

[411A]

As to which engines on that AF -328, in 1972, it would certainly have the latest dash number (JT4A-11) at that time, these had 17,500 lbs of thrust each, and the maximum gross weight was up to 312,000 lbs. They were guzzlers, but had adequate power. Funny is, their performance was great at higher levels above FL350, whereas the JT3D fans "ran out" of vitamins and ideas above FL350.


Yup, quite true.
So much so, in fact, that a few unknowning pilots tried to climb 'em well above their optimum altitude for the weight (mass, for you disadvantaged European folks), and encountered the classic jet upset.

Not good.
Once or twice, engines chucked right off the pylon, on the way down.:uhoh:

[mustafagander]

WHBM,

Don't forget that the 707-120 fan conversion also required the wing glove panel job. This was a big job - trust me, I fitted a few - and hence expensive. For shorter legs it may well have been uneconomical and so certain airlines would opt out.

[b377]

For you guys with first hand savvy I'll start a thread on performance of these first generation engines at high airports like Bogota, Quito, La Paz, etc. I believe there used to be a sacrifice in MTOF ?

Look out for the thread. I in turn will look forward to comments.


Mustafagander:
What was the wing glove panel?

[BelArgUSA]

Hola, compañero b377 -
xxx
The wing glove panel was an aerodynamic improvement that appeared with the 720 initially, and was soon offered to the 707-100. It was a different profile between the leading edge from inner engines, and the junction of the wing to the fuselage.
xxx
Did not apply to the 707-300, having a completely different (larger) wing.
xxx
:ok:
Happy contrails

[Spooky 2]

It is true that all of the Western Airlines B720B-047 were delievered as fan powered aircraft but Western merged with Pacific Northern in 1967 and in that merger acquired three B720A's, I seem to recall that one was a former Braniff -048 and the others were original PNA 062's but I could be wrong about the origin. They operated these aircaft for a number of years in to the early 70's

[mustafagander]

BelArg is correct about glove panels. They weren't just a chunk of Micarta tossed onto the upper inboard surface of the wing, they were contoured and hence the thickness varied all over the panel.

While they did wonders (so we were told!!) for the aerodynamics, there were dozens and dozens of 10-32 screws required to attach them. The problem with these screws is that the anchor nuts were sealed domes in the wing fuel tanks. Guess what happened if you screwed an over length screw in? Push the dome off and voila - a fuel leak, so into the tank and replace the dome nut. Hence every screw hole depth was measured and the correct length screw fitted. Not a quick job, but it did keep the apprentices occupied.

[BelArgUSA]

Hola Spooky -
xxx
I recall these 720-062 from Pacific Northern.
When layoff 1974, PanAm helped to get me with AeroAmerica.
Was a BFI Boeing Field operator with 707/720. Base also TXL West Berlin.
These two 720-062 were "spare parts" for AeroAmerica planes in BFI.
Stole a "720" control wheel emblem (souvenir) from one of their cockpits...!
xxx
:ok:
Happy contrails

[Spooky 2]

Amazing that the control wheel "hub cap" was still left as those things disapeared pretty fast.

[Liffy 1M]

Here's a real rarity - an ex-SABENA 707-329 which was converted to JT3D power in Israel in about 2003.

http://www.airliners.net/photo/Israel-Air-Force/Boeing-707-329%28KC%29-Re-em/1036674

[BelArgUSA]

Hola Liffy -
xxx
Definitely a rarity, a straight 320 converted to JT3D... Would not believe it, although IAI Engineering does at times, incredible things in TLV. It is in effect a straight 329 since it does NOT have the side cargo door, must be OO-SJC, D, E. F or G... I do not know which one of these survived. SJA nose is in the BRU Air Museum, and Sabena lost SJB in an accident.
xxx
A strange fact though, due to the "military" nature of this aircraft, is that IAI did not install a cargo door after all. Ok, then. it might be the only (or very few) 320/JT4A converted to JT3D. Another "exception" in what was, supposedly never done. I knew that Boeing made some tankers out of 320C airplanes (Iranian Air Force, and Spain)...
xxx
Thanks, Liffy
:ok:
Happy contrails

[WHBM]

must be OO-SJC, D, E. F or G... I do not know which one of these survived.
It was SJC. The detail is in the spreadsheet I linked to in post 4 above.