SNECMA TF104/TF106/TF306 Turbofans

overscan (PaulMM)

Administrator
Staff member
Joined
27 December 2005
Messages
16,431
Reaction score
19,060
Some good info here:
In 1959 Pratt & Whitney Aircraft, through the United Aircraft Corporation purchased a minor holding in SNECMA. Two important outcomes of this agreement have been SNECMA's overhaul of P&W engines in Europe, notably the JT3 and JT4, and France's development of the P&W JTF10 turbofan for the Mirage IIIV V/STOL interceptor. This latter work has evolved in two stages, producing first the TF104 and 106, of 10,500lb and 11,210lb thrust, respectively (both of which were closely derived from the original civil JTF10) and secondly the TF306, more closely related to the P&W TF30 powering the General Dynamics F-111.

Read more:

 
Thanks again Overscan ;)

It should be interesting to know the M-45G rate.
 
Ah, but the interesting thing is why P&W was allowed to buy such a holding, 'twas part of the contract to allow French production of the military JT4C (J75) for the proposed Mirage IVB. Personally, I think SNECMA did better with the TF30 than P&W did; much as the Swedes got better performance from an afterburning Avon than RR did, for equivalent marks.
 
TF104

Dry thrust: 3800kg
A/B thrust: 5800-6200kg
SFC: 0.6/2.55
Bypass ratio: 1.5
Weight: 1550kg
length: 5m
Diameter: 1.3m

TF106A2
Dry thrust: 4200kg
A/B thrust: 7500kg (TF106A3, 500kg more thrust)
SFC: 0.66/2.5
Bypass ratio: 1.3
Mass: 1780kg

TF306
Dry thrust: 5210kg (C), 5780kg (D), 5970kg (E), 6550kg (F)
A/B thrust: 9150kg (C), 10000kg (D), 10330kg (E), 11000kg (F)
SFC: 0.65/2.35
Bypass ratio: 1.03
Mass: 1750kg
Length: 5.3m
Diameter: 1.2m

Liebert & Buyck, Mirage F1 et les Mirage de seconde generation
 
Interesting, Snecma worked in 1966/1967 on "ramjet" TF 306 for "high Mach fighter projects" (M 48 and M51) (think it was like the PW J58 on SR-71).
 
Le Fana mention the deal in its 336, October 1997 edition. Think SNECMA gave 10.9% or so.

Well, J.C Carbonel had a nice article on the J-58 at its "aerostories" website.
It briefly mentioned that the J-58 had been considered for Concorde before the Olympus came in, hence the presence of the engine at Le Bourget airshow in 1963...

The Mirage IVB was supposed to be 57 tons, 5000 km range, enlarged variant of the Mirage IVA.
Alas, France didn't have an engine powerfull enough for such a monster. As a consequence, four engines were considered
- RB-142
- Olympus
- Iroquois (damn... the CF-105 engine)
- And the J-75!

But De Gaulle aparently stated that the french nuclear bomber couldn't rely on foreign engines. Hence the return to the IVA.. and buying of KC-135FR in 1964.
 
Re: SNECMA TF-106 experimental afterburning turbofan......

Dear Boys and Girls, here is an article in French about the SNECMA TF-106 experimental afterburning turbofan which was derived from the Pratt & Whitney JTF10 engine. It was flight-tested in the Avions Marcel Dassault Mirage III T test-bed and was also used for the early test-flights of the Avions Marcel Dassault Mirage III V-01 VTOL fighter prototype......

Moderators; this Topic is a suitable candidate for transfer to the new Propulsion forum; these engines were experimental and never made it to full production status……

The article comes from the 16th June 1961 issue of Les Ailes......

Terry (Caravellarella)
 
Were TF306 to find its way in production aircraft would the United States be able to impose export restrictions on say Mirage F3?
 
I wondered what was in te fine print of the deal so to speak. If it was just a license agreement it would had been obvious. But SNECMA had gotten the design as part of the partnership deal with P+W and then went on to modify it a fair deal.
 
I wish I could know when was the TF306 officially abandonned.
- Aviation Magazine says December 1969.
- Both Mirage F2 and G flew until 1971 when the former was retired and the later crashed.
- But the writting was on the wall for TF306 since the Mirage F3 had been scrapped in 1967 and the 9K50, scaled-down F1 chosen instead.

So I still have no idea whether that engine was stopped in 1967 (F3) 1968 (M53 development began) or 1969 (December)

Sweet Jesus. The years 1965-1975 saw a complete mess of prototypes and requirements - between Dassault, the AdA, Aéronavale, and French ministry of Defense.
And SNECMA for the engines: 9K50 and M45 and M53 and TF106 and TF306.
And the Jaguar on top of that.
 
You have cited reliable sources, but there is also the official website of Dassault and Camareo 10 "T2 military aircraft". who knows maybe there is an exact confirmation in the latter.
 
Turbo-Ramjet Combination Engine using a TF106 core:

Very interesting. A long time ago (2006 I think) Le Fana de l'aviation had a monography related to Dassault Mach 3+ projects (MD-750 and countless others). And turboramjet TF306s featured prominently, which makes some sense before 1970 and the M53. TF306 was to be SNECMA entry into the supersonic fighter turbofan area, post- Atar. But it ended too expensive and troubled, and American with that - anatema to De Gaulle and Pompidou policies...
 
Was the TF-106 the same diameter as the tf-30 or was it scaled down, because it would be very impressive if the French were able to put a 49in dimaitor engine into a plane biult for a 39in engine (The Mirage III-T).
 
Ok I don't want to create a new thread so I'm asking the question here.

What was wrong with the TF104 / 106 / 30 / 306 family of Pratt turbofans ? And how did it impacted SNECMA own take at improving that engine ?

I presently have the following (scattered) elements
- TF30 started as the F6D subsonic turbofan
- Trouble started when Pratt made it supersonic for the F-111B and later the Tomcat
- Even subsonic, it wasn't that good, as A-7 got a massive performance boost when USAF, then USN, switched to Allison TF41 / Spey
- SNECMA seemingly made a better job than Pratt on TF306, correcting a turbine blade problem
- Mirage F2 and Mirage G seems to have flown pretty well (1966-69 and 1967-71 respectively)
- So did the TF30s A-7, never heard of deadly compressor stalls issues for A-7s and Mirage F2 / G
- Before that however, TF106 in Mirage III-T and III-V 01 seemingly sucked immensely
- compressor stalls seems to be a common feature between SNECMA issues and the Tomcat own problems
- yet as far as the F-111A was concerned, the intakes were trickier too, so not TF30 fault there

Was there some kind of flaw in the TF30 compressor ? something akin to rampant compressor stalls that could be aggravated by ill-suited intakes - as shown by the Mirage III-T (too small intakes) and F-111 (intakes done wrong) ?
 
Basically, state of the art for fan & compressor design from the late 1950s. The TF30 performed reasonably well for the time, but the fan / compressor were not very tolerant of inlet airflow distortion. Bad inlet design (early F-111) can cause distortion, better inlet design (F-14) can still have high levels of distortion at high AOA and sideslip. The A-7 engines had some problems with steam ingestion on the carrier catapult.

The TF30-P-100/111 engine for the F-111F had a redesigned fan and low compressor with a bulged flow path in the LPC that increases airflow, pressure ratio, and distortion tolerance, which in addition to a higher temperature capable turbine resulted in a big step up in performance, with takeoff max AB thrust going up from the 19k range to 25k lbs thrust. In the mid 1980s, P&W proposed developing a similar fan/LPC design for the F-14 P-414 engine, but the Navy didn’t fund it..

The A-7 performance increase with the TF41 engine was primarily due to it being a bigger engine with higher airflow, pushing the thrust up from 12.5k to the 14.5k lb range. The TF30 was lighter and had better SFC, giving it some performance advantages over the TF41, but it was hard to argue against the increased thrust.
 
The TF30-P-100/111 engine for the F-111F had a redesigned fan and low compressor with a bulged flow path in the LPC that increases airflow, pressure ratio, and distortion tolerance, which in addition to a higher temperature capable turbine resulted in a big step up in performance, with takeoff max AB thrust going up from the 19k range to 25k lbs thrust. In the mid 1980s, P&W proposed developing a similar fan/LPC design for the F-14 P-414 engine, but the Navy didn’t fund it..
By then the F101/110 was well on its way I guess, but I read the P-100 was introduced in 1970 with the 111F so how come P&W offered the design so late for F-14?
 
In 1970, the F-14 was brand new and the TF30 was considered to be an interim engine until the F401 was ready. Then the F401 was cancelled and the F-14 was in full production with the original TF30-P-412. Some fan blade containment issues resulted in the P-414 version that introduced beefed up fan cases and changes to the fan stator inner rub strips to eliminate the possibility of fan blades coming thru the cases and prevent any fan rub titanium fires. The customer was more concerned with safety and durability improvements with their Component Improvement Program dollars than improving performance and operability.

As noted, by the time it was thought that changing the fan / LPC configuration, the F101DFE program was bringing the F110 engine to reality. When the F110-400 was installed in the F-14, the performance that was predicted for the F401 became reality.
 
Thanks you for the explanations. Of course the F-14D (mostly) went by the window, courtesy of the aptly named Dick Cheney - and the Tomcat soldiered on with TF30s until 2006.
 
Interesting technical tidbit regarding the fan containment fix implemented on the TF30-P-414. The relatively obvious action is to beef up the fan cases to be able to take the hit from a released fan blade and keep it inside the engine. This was accomplished with about 200 lbs of additional metal in the cases.

However, with the blade released at high rpm, there is a huge imbalance that deflects the fan rotor off center. Rubbing off the titanium air seals between the fan disks against the the fan stator titanium inner shrouds generated enough heat to start a titanium fire, known in the industry as a “rapid oxidation event”. While they are hard to start, titanium fires very energetic and are as much a risk to airframe integrity as a released fan blade.

The fix was to install a steel rub layer on the fan stator inner shrouds. Heavy rub would still occur during a blade release event, but the melting temperature of the steel was below the ignition temperature of the titanium, acting as a molten metal journal bearing, preventing the titanium fire until the wreaked engine slowed to rotor stop.
 
Last edited:
In 1970, the F-14 was brand new and the TF30 was considered to be an interim engine until the F401 was ready. Then the F401 was cancelled and the F-14 was in full production with the original TF30-P-412. Some fan blade containment issues resulted in the P-414 version that introduced beefed up fan cases and changes to the fan stator inner rub strips to eliminate the possibility of fan blades coming thru the cases and prevent any fan rub titanium fires. The customer was more concerned with safety and durability improvements with their Component Improvement Program dollars than improving performance and operability.

As noted, by the time it was thought that changing the fan / LPC configuration, the F101DFE program was bringing the F110 engine to reality. When the F110-400 was installed in the F-14, the performance that was predicted for the F401 became reality.

Actually, the F-110 never matched the F401's performance. It was 1000 lbs heavier, had 1200 lbs less thrust, and had higher fuel consumption. Also, the F-14D weighed 5000 lbs more than the F401-equipped F-14B. The F-110 was designed to fit both the F-15 and F-14, whereas the F401 with its larger fan/higher BPR could only fit in the F-14; an aircraft designed from the outset to have 10,000 lbs more thrust than the F-15. Instead, the F-15 ended up with more thrust than the F-14. An absolute travesty.
 
The A-7 performance increase with the TF41 engine was primarily due to it being a bigger engine with higher airflow, pushing the thrust up from 12.5k to the 14.5k lb range. The TF30 was lighter and had better SFC, giving it some performance advantages over the TF41, but it was hard to argue against the increased thrust.
I thought the TF30 was larger than the TF41? Did the A-7 use a smaller/cut down version of it?
 
The versions of the TF30 used in the A7 were non-afterburning, which shorted the engine by about half. These TF30s are slightly smaller than the TF41.
 
Ah, that's interesting. Was the TF30 in the A-7 otherwise cut down in core length (or diameter) compared to the "proper" TF30, or was the AB section in the TF30 just so long that a AB-less TF30 ends up smaller than an AB-less Spey despite the fact that the TF30 with AB is a larger engine than an Spey with AB?
 
No, the A7 variants (P-6, P-8, P-408) of the TF30 were virtually the same as the P-3, P-7, and P-9 engines for the F111, and the P-412 engine for the F-14, minus the afterburner and AB fuel control.

The specifications that I have found on Wikipedia and National Aerospace Museum are:

TF30-P-6 11,350 lbs thrust, 233 lbs per second airflow / 2715 lbs, 128.1” long, 42” diameter. Bypass ratio approx 1:1

TF30-P-8 12,200 lbs thrust

TF30-P-408 13,390 lbs thrust

TF41-A-1 14,250 lbs thrust, 258 lbs per second airflow, 3511 lbs, 114.5” long, 40” diameter, bypass ratio 0.78:1

So the TF41 is slightly smaller overall than the TF30, but 800 lbs heavier. You do have to be careful with the dimensional specifications, since it depends on what they are measuring. The quoted number can be the overall diameter including the accessories like gearbox and fuel controls which likely were set by the F111 versions for the TF30, while the TF41 fan inlet diameter may have actually been slightly larger, based on the airflow specs. Similarly, the TF30 length is based on the F111 engine fan duct length for commonality, while the TF41 was built specifically for the A7 installation. Both engines had a long sheet metal exhaust nozzle (unique to each engine) mounted to the rear of the fan ducts that extended to the rear of the airframe.
 
No, the A7 variants (P-6, P-8, P-408) of the TF30 were virtually the same as the P-3, P-7, and P-9 engines for the F111, and the P-412 engine for the F-14, minus the afterburner and AB fuel control.

...

TF30-P-8 12,200 lbs thrust

Per AvWeek 21 Feb 1966, in the original USAF spec for the A-7D its TF30-P-8 was to be fitted with a 'short' afterburner to push take-off thrust to 14,000lb. No designation given for this mongrel.

That's why the Spey 201 had to be pushed to 14,500lb for the A-7.
 

Similar threads

Back
Top Bottom