Breguet 941 STOL and Related Projects

[Archibald]

Re: Breguet 941 VTOL and related projects

IIRC, the end result of all the "Model 188" demos and STOLPort studies was as follows:

Since the STOLPort was likely to be a "brownfield" site on the edge of town, it made sense to make the runway slightly longer and accept somewhat higher T/O and approach speeds. Importantly, this eased the engine-out control case to the point where the cross-shafted engines of the 941 were not needed. However, four engines were still required (for engine-out and flap blowing) together with robust controls (spoilers and a large double-hinged rudder).

This led to a joint US airline spec for a 48-seat STOL transport, and the DH Dash 7 was designed to it.

Vey interesting. And that probably made a huge difference in maintenance costs. The Armée de l'Air actually got four Breguet 941S in 1971, they flew along Transalls at the 62ème escadre de transport but were dropped in 1974 as too expensive in maintenance. I wondered about a DASH-7 connection, so thank you.
For the record, Breguet merged with Dassault in December 1971 and I wondered why Dassault didn't tried to market the 941. The DASH-7 is part of the answer. The failures of both Falcon 30 (regional jet, too early) and the Mercure airliner are the other part.
It is interesting to note that the DASH-7 STOL was relaxed on the DASH-8 because airlines were not really interested. Two engines and better cruise performance, that's what the market really wanted.

Of the four Breguet 941 build, one is at Le Bourget aviation museum and another has recently been saved from scrapping by LEs ailes anciennes de Toulouse, thank to crowdfunding.
http://www.aatlse.org/news611.php

 

[LowObservable]

The Dash 7 competed head-on with the less expensive Fokker F27 and F50. By the late 1970s, after the raising of aircraft size limits on Part 298 operators, and after deregulation made it easier for smaller airlines to compete on short, low-traffic routes (many of them previously owned and inefficiently served by majors), the STOLPort craze had subsided. All that was necessary for the new "supercommuters" - Dash 8, Saab 340 and EMB-120 - was to go anywhere an F27 or a Convair could go but at a lower aircraft-mile cost.

 

[VictorXL188]

Amongst the pics of the Breguet 940/941/941S I never saw any of the tests carried out in central Paris, so I hope these may be of interest to people

 

[VictorXL188]

Apologies missed it in the middle of a bunch of others. :

 

[circle-5]

Amongst the pics of the Breguet 940/941/941S I never saw any of the tests carried out in central Paris, so I hope these may be of interest to people

I suspect this photo was actually taken at the heliport in Issy-les-Moulineaux, which is just outside Paris. The telephoto lens makes the Eiffel Tower appear closer.

 

[Archibald]

and your intuition was right, the Breguet 941 was extensively tested at Issy les moulineaux.

 

[JC Carbonel]

Hello Boys and Girls

you maybe interested to know my book on the Br 94 series is planned for 2018 at Artipresse. I had a mock-up cover at Telford. There will be a lot of new material coming from interview with pilots from CEAM and E.T. 03.062. I have not been able to circonstantiate the floatplane version from original Breguet material so I am still undecided as to wether to include it or not.
Coverage will begins with the Br 940.01 of 1954 to the last flight of the type on 18 july 1974.

JCC

 

[Dynoman]

JC, will you be including the US airline demonstration flights of the MD-188 version?

 

[Archibald]

Excellent !

 

[JC Carbonel]

Both US escapades (Br 941 / Br 941S) are covered. I have a Breguet report dated 1970 which covers the Br 941S trip. The MD 188(S) affair is spread on 5 pages of the word manuscript. I guess it would amount to slightly more pages once the book is layouted.

I also covers various European trips including the "round-Europe" Br 941 campaign , NASA experimentations, flights to Italy and Germany, the aborted flight to Middle East. One of my pilots told me he had done a flight into Africa but I have not been able to substantiate it (and he did not offer to make copy of his logbook so I did not insist). Again I understand some display operation was planned with Short in UK but I have no proof it was actually flown. Often archives are thick with planning memos but light on actual operation reports (and this is no specific of the Breguet research)

JCC

 

[patvig]

There is one (the only remaining ?) Br 941 in Toulouse, in the collection of Ailes Anciennes. Their aircraft list is available at http://www.aatlse.org/?coll=avion

 

[JC Carbonel]

AFAIK the Br 941 did not survive. But two Br 941 S (that's 50% of the production!) survive : one in Toulouse, one in Musée de l'Air (le Bourget)

JCC

 

[Archibald]

There were six of them (I was wrong), the "integral" 940 demonstrator, then a Breguet 941, and then the four Breguet 941S that went to 62ème escadre de transport until 1974.
Of these four, as said above, one is MAE in Le Bourget, another has recently be saved through a kickstarted campaign by Les ailes anciennes de Toulouse.

The two others 941S, the 941, and the 940 were all scrapped.

http://histaero.blogspot.fr/2014/11/breguet-940941-linvention-de-ladac.html

 

[hesham]

From Icare 1969.

 

[Dynoman]

In the NASA Publication, Memoirs of an Aeronautical Engineer: Flight Tests at Ames Research Center 1940-1970, author Seth Anderson recounts the results of the 10 hour test program conducted by NASA at the French Flight Test Center in Istres in 1963 and then a 20 hour program in Toulouse in 1966. The program involved transition from cruise to approach speed; VFR and IFR landing patterns; airspeed and flight path control for these same tasks; landing flare technique and method of control; and takeoff and go-around characteristics. The engineers from Ames found that the aircraft (941S) demonstrated marginal performance in that both heading and flight path control while flying at relatively low altitudes and airspeeds during the ILS approaches. Their recommendations were to develop better displays and controls for arresting the descent rates during IFR operations. Ames engineers were also involved in the MD-188 operational tests at Dulles in Washington, D.C. He cites the added weight and complexity of the interconnect system needed for safe low speed operation as one of the aircraft's failings. He also stated that airspace infrastructural changes were needed for the integration of national STOL operations.

 

[Viper2000]

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030032368.pdf

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19690003921.pdf

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19640007812.pdf

https://apps.dtic.mil/dtic/tr/fulltext/u2/689106.pdf

There are lots of other papers about the aircraft on NTRS, and DTIC; they're not always easy to find, but it's worthwhile. The American reports often refer to it in the most generic terms possible, e.g. "A deflected slipstream STOL transport having four interconnected propellers".

The aircraft also featured as a baseline for many subsequent studies; the relevance of these to this thread depends upon how far you want to stretch "related projects".

 

[hesham]

From Ailes 1/6/1962,

the Breguet 947 & 947R,a small Info.

 

[hesham]

From Krila 4/1957,

that artist drawing shows a double-deck to it.

 

[Tonton-42]

[QUOTE = "Jemiba, message: 88584, membre: 80"]
Re: Breguet 941 VTOL et projets connexes

"..le Br. 941 avec un camouflage militaire français .."

De Jean Cuny "Les Avions Breguet":
[/CITATION]In 1998 september I saw the unique 941 in the MAE storage. It had the coulors of French AA but it was partielly burned in 1989 (if I remember well ...) and stayed out without protection fromthat date ... I was very sad to see that !

 

[Cy-27]

Following on from Archibald's post (#133) the attached photo of Br.341S serial 305 was taken at Les Ailes Anciennes de Toulouse in June 2018. It looked in a sorry state and without a tail fin but I think the kick-start funding may eventually be able to see it restored.

 

[Archibald]

I'm confident Aeroscopia / Airbus money will save that flying wonder...

He cites the added weight and complexity of the interconnect system needed for safe low speed operation as one of the aircraft's failings

Yes, it was really this system weight and complexity that doomed the Breguet. The AdA quited liked the four aircraft it got in 70-74... except for its mechanics. They were gone by 1974.

I'm left wondering if that system was really necessary, considering Turbomeca stellar track record on turbines (helicopters and some aircraft together).

Could the Breguet had bitten the bullet and flown without the interconnecting system ?

My biggest regret with that Breguet - that nobody ever tried a C-130 / Forrestal -like carrier landing, on Foch or Clemenceau. In Issy-les-Moulineaux they managed to land the 941 is 120 m, and this is merely half the length of a Clemenceau deck. What an amazing feat and sight that would have been !!

 

[Dynoman]

In January 1964 the US Army, who completed a Flying Qualities and Performance Evaluation of the Breguet 941, considered a runaway prop or prop failure scenario (i.e. causing asymmetrical thrust). The Army believed that the aircraft was controllable in both asymmetric power and asymmetric thrust configurations for STOL takeoff (ATA-TR-63-6, Flying Qualities and Performance Eval, 1964, p.2).

 

[Archibald]

Fact is that the V-22 Osprey (IMHO) has no interconnecting system between its engines. Of course its safety record is not very good, but that's a different issue.

 

[Dynoman]

It would be fun to see a 'Credible Sport' JATO version of the 941 or a modern composite airframe design of the aircraft using the wing tip vortex influencing props, segmented flaps and shaft interconnect. I believe the 941's original approach speed was approximately 60 kts!

 

[aim9xray]

Fact is that the V-22 Osprey (IMHO) has no interconnecting system between its engines. Of course its safety record is not very good, but that's a different issue.

Umm. No. V-22 does have cross-shafting between engines.
Relative safety of the aircraft is a matter of record.

 

[Caravellarella]

Dear Boys & Girls, just to remind you, if you are on Facebook; I have a Facebook Group dedicated to the Breguet 941 series - https://www.facebook.com/groups/831038880299915/

Terry (Caravellarella)

 

[hesham]

From Aviation magazine 1961.

 

[blackkite]

Hi Br940.
https://modernwartech.blog.hu/2019/06/10/vtol_60_9_resz_a_breguet_br_941_es_tipuscsaladja

 

[uk 75]

Were there any plans to use the Breguet 941 to resupply the 150 Mirage Vstols which France planned to replace its F100 Super Sabres..Would make for some great artwork. The Bundeswehr using Do231s and Vak191s and the RAF 1154 Harriers with HS129s. Would make a great graphic novel.

 

[Archibald]

Who needs Forrestals and C-130 Hercules, really ? Breguet 941 and Clemenceaus could do that, to.

http://a3ba103.free.fr/Cerpa/Guerre_froide_1961_06_premier_vol_breguet_941.pdf

la Marine nationale envisage pendant un temps de l’utiliser sur le porte-avions Clemenceau pour la lutte anti sous-marine.

ASW Breguet 941 out of Clemenceau-class carriers. No need for catapults or arrestor gear: the ships were 260 m long, the Breguet could lift-off in 200 m and land in 120 m.
That would have been completely awesome. And could also have worked as COD, AEW...

COD confirmed here

http://histaero.blogspot.com/2014/11/breguet-940941-linvention-de-ladac.html

Dans le même temps, la Marine Nationale s'intéresse également à l'appareil, en vue d'acquérir une version de liaison pour relier ses porte-avions à la terre, à la manière des C-2 "Greyhound" américains.

I wouldn't be surprised to find an AEW proposal someday. At the exact same time the British had the P.139 (think it was its name) for AEW and the French Navy also studied somewhat similar aircraft (not Breguet 941, admittedly). It wouldn't be too hard to pack the E-1B APS-96 radar into the Breguet airframe.

 

[orlovsky]

I guess this has been linked here before, but just in case: http://aviationarchives.blogspot.com/2019/09/carrier-suitability-of-mcdonnell-model.html

 

[Archibald]

Many thanks ! can't remember how was MD 188E related to the Breguet...

 

[orlovsky]

The McDonnell 188 was to be a license produced Version of the Breguet 941. I think they looked at all kinds of military and civil transport.

 

[Archibald]

Many thanks again. 500 ft is (roughly) 150 m and 700 ft, (approximatively) 213 m.

Basically: could have landed on Audacious, Clemenceau, Essex and Midways "older" carriers, any US super carrier after them. Plus any large US amphibious from Tarawa onwards.
By contrast Iwo Jima, Invincible, Asturias and Garibaldi: not possible. Too short: merely 180 m flight decks.

EDIT: I attach the Pdf just in case the blog vanishes...

 

[apparition13]

I wouldn't be surprised to find an AEW proposal someday. At the exact same time the British had the P.139 (think it was its name) for AEW and the French Navy also studied somewhat similar aircraft (not Breguet 941, admittedly). It wouldn't be too hard to pack the E-1B APS-96 radar into the Breguet airframe.

AEW needs multi-hour loiter time. Do these designs have the fuel capacity to do that? Can they be given that fuel capacity? Most importantly for carrier operations, can the wings fold, what with the cross shafting and all? If yes, then they could have been very useful, and could have replaced the S-2 family on smaller carriers. I'd still rather have CL84-8 for a CSA base aircraft for carrier ops, but the 941 family should have been way more successful. I can see it working in the C-27 role, for starters, with even better STOL performance.

 

[Dynoman]

A four-engine wing mounted propeller driven aircraft with folding wings was designed into a naval variant of the LTV XC-142. The design was a capable aircraft for cargo and troop carriage, however the down wash from the blades while in vertical flight was too much for the Navy (concerns of blowing men overboard and flying debris on a confined deck) and the vibrations experienced from the drive shafts was problematic for the pilots. A STOL design may have been more beneficial, such as in the case of the Breguet 941, when an arresting system or a catapult system has failed and the 'mail' (and cargo) still must get through.

(Below a picture of LTV XC-142 as a naval variant)

https://www.secretprojects.co.uk/threads/vought-xc-142-developments.9009/#lg=thread-9009&slide=5

 

[hesham]

From FR 10/1975.

 

[Archibald]

At this point (1975) the 4 Breguet 941S build had been retired from their Armée de l'Air transport squadron in Evreux - because of maintenance costs... (sad).