Supersonic Etendards instead of Crusaders?

[zen]

What happens if Dassault gets his hands on a jet engine that fits the Etendard and allows it to become a properly supersonic fighter?

Could this tip the balance and see them ordered instead of F8 Crusaders?

 

[overscan (PaulMM)]

They had a suitable engine - the ATAR. If you used the standard version with afterburner, it could have supersonic. They didn't, because it wasn't relevant to its mission.

 

[uk 75]

Etendard is the only European conventional take off carrier aircraft programme that could have been improved to meet the requirement for an RN Sea Vixen replacement.
An RN version might have saved Hermes as a CTOL carrier.

 

[zen]

Uou see.....It struck me reading about the Crusader and Etendard that had the right engine(s) been available. Dassault could have produced a more Fighter optimised version.
That such ought to not breach the operating limits of Clemenceau.

In essence the later Mirage G and even the Jaguar M held such potential.....but at too high a price.

Granted it might not be as capable as the much vaunted F4.....but it might have given the F8 a run for it's money and offered the RN an alternative to the cancelled F.177.
As uk75 says it might have offered an alternative to the lumberung Sea Vixen.

Reheat does seem the logical way forward. For a modest increase in weight....maybe no more thsn 1,000lb a substantial increase in thrust, maybe 5,000lb. Albeit consuming a lot more fuel.

I've often suggested the late 50's to early 60’s RB.153.
Or the later M.45

But even reheated Atar ought to deliver.

 

[Archibald]

Atar 8K50 was a non afterburning 9K50. The former for the S.E the latter for the F1. Check my thread to see what a mixed F1 / S.E might have been.
Of course the J52 of Skyhawk fame had better potential including with an afterburner. Guess what ? the S.E nearly got a Skyhawk engine in '73. The aeronavale wanted it but the french gvt told them to take an Atar 8K50.

 

[H_K]

They had a suitable engine - the ATAR. If you used the standard version with afterburner, it could have supersonic. They didn't, because it wasn't relevant to its mission.

The Atar with reheat would be too long, too heavy, and too thirsty for the Etendard. The CoG implications alone make it a non-starter, even before you start lengthening the rear fuselage, adding fuel tanks etc.

I’ve looked into this and can’t find a way to do it without essentially designing a whole new aircraft. It would look like a Mirage F1, but with an enlarged Etendard wing.

Agree with @zen that the RB.153 is a much better fit… almost a drop-in for the Atar 8. Dry thrust is very low however (6,850lbs)… not sure how to fix that.

Below is a comparison of the engine sizes - Atar 8 vs Atar 9 vs RB.153. And a plan view of the early Etendard IV design (with Atar 101).

 

[Archibald]

I checked dimensions of the Etendard IVM, S.E and Mirage F1. The Etendard are barely shorter than a Mirage F1 : 14.3 m vs 15.3 m. They have larger span, where they really differ indeed is weight: 10 tons for an Etendard IV, 12 tons for a S.E, 16 tons for a Mirage F1.

How can a Mirage F1 then packs 1) a bulky AB plus 2) 4 to 6 mt + of internal fuel - inside a fuselage that is a) very similar and b) "only" 1 meter longer ?
Put otherwise: what, inside an Etendard fuselage, ate 4 to 6 mt of internal fuel, compared to a Mirage F1 ? where have the fuel tanks gone ? middle-mounted wing ? avionics ? undercarriage ? something else ?

 

[Archibald]

Where it gets really interesting (and weird, and ironic altogether) is: the M53-2 (at least) was sold by SNECMA circa 1969 as matching an Atar 9 well enough it could be swapped inside the older Mirages engine bays. and so it was at least, inside the F1-M53.

BUT, the M45 now orphan of the AFVG and essentially unused post 1968, would have actually been a better fit, although it lacked thrust: 5500 kg put it below the older Atar 9 variants (9C: 6000 kg, 9K 6700 kg, 9K50 7200 kg). But it weight 50% less, was merely half the length and Sfc would have dropped to the ground.

Imagine Etendard IVM with M45, with or without afterburner. Unlike a M53 the engine was minuscule, so provided CoG not end very screwed, massive range gains could happen.

Heck, I once dreamed of a Mirage IV upgrade, not with Speys or M53, but M45s. Wouldn't have lost a lot of thrust (and it had huge RATO bottles to help takeoff) but got a big range gain, perhaps 20 or 30%, starting from 4000 km ferry range and 2500 km combat range - 1250 km radius without C-135FR to help.

 

[H_K]

How can a Mirage F1 then packs 1) a bulky AB plus 2) 4 to 6 mt + of internal fuel - inside a fuselage that is a) very similar and b) "only" 1 meter longer ?

Simple answer. The Mirage F1 has a wider fuselage so that the landing gear and fuel tanks wrap around the engine. The Etendard has a very slim fuselage where all these elements are in a row - fuel tanks in front, landing gear middle, engine in the rear.

That’s why you can’t fit an Atar 9 in an Etendard without ending up with something that basically looks like a Mirage F1.

 

[zen]

On a theoretical level RR could increase the bypass ratio and exterior diameter to match the Atar. This would increase thrust for a modest weight increase and only a minor increase in length.
It would mostly be felt in the increased diameter of the reheat chamber.

 

[zen]

If Atar 8 is 0.92m diameter
Therefore 0.6647610055 sqm

And RB.153 is 0.75m diameter Therefore 0.4417864669 sqm

Meaning potential for 0.2229745386 sqm increase.

In theory that might increase dry thrust from 6,850lb (3107.108kg) to 10,307lb (4,679.378kg)

Which since I remember Gunston saying RR were limited to 17,000lb before needing reduction gearing for the fan. Then this might be achievable.

And hypothetically this might translate from 11,250lb (5,107.5kg) reheated to 16,927lb (7,684.858kg).

Will add more to this post later.

 

[H_K]

If Atar 8 is 0.92m diameter
And RB.153 is 0.75m diameter

Careful comparing diameters. The Atar’s inlet diameter is 0.84-0.86m (outside dimensions) or 0.79m (inside dimensions). One of these is the correct number to compare to the RB.153’s 0.75m.

When I overlaid the engine drawings I posted earlier at the same scale, there was no significant difference in diameter… if anything the RB.153 was a little wider aft due to the big reheat section.

 

[zen]

Quite right H_K!
I note the reheat chamber is 0.855m or 33.66" diameter.
Wereas the Atar dry exhaust is 0.761m or 29.69".

 

[zen]

Alternative path forward

The RB.153/17 was the first engine to be built in 1959-60 and was a single shaft turbojet with a 9-stage axial compressor driven by a 2-stage turbine. 65 inches long and 25 in diameter the engine delivered 3934 lb thrust dry and 5463 lbs with afterburner.

Theoretically a pair of these as used in Gnat MkV might suffice in Etendard II?
Length: 65" = 1.651m
Diameter: 25" = 0.635m
Dry: 3,934lb = 1,788kg
Reheat: 5,463lb = 2,483kg

 

[H_K]

@zen Nice! Yes the RB.153-17’s dimensions and weights (388kg with reheat) seem similar to the Gabizo, so that could make for a nice drop-in replacement. Not sure about mass flow… perhaps the air intakes would have to be expanded.

Biggest challenge would be to add area ruling to the Etendard II’s rather “fat” fuselage!

Here’s the Etendard II “Marine” (1956) for reference:

 

[zen]

For comparison sakes and with depictions of the early RB.153 turbojet design. The Folland Gnat thread yields results.
Potentially scale images there.
Link 1 Gnat MkV
Post in thread 'Folland Gnat - Development & Derivatives' https://www.secretprojects.co.uk/threads/folland-gnat-development-derivatives.769/post-8118

Link 2 Fo.147
Post in thread 'Folland Gnat - Development & Derivatives' https://www.secretprojects.co.uk/threads/folland-gnat-development-derivatives.769/post-221608

Additional
Pursuing through the Gnat thread, a picture of the Gnat MkV looking both very grainy and dark but very snazzy as a design and states engine options of RB.153 tirbojets or BS. Viper 20s?

 

[H_K]

Biggest challenge would be to add area ruling to the Etendard II’s rather “fat” fuselage!

Here’s a sectional view of the Etendard II vs Etendard IV… sections D, E, F, G (top) would have to be area ruled. Not easy but perhaps doable if a small loss of internal fuel capacity can be accepted.

(The Etendard II’s internal capacity of 2,700L is actually quite decent - includes 600L in wing tanks and 300L in rocket bay)

 

[Deleted member 2278]

Biggest challenge would be to add area ruling to the Etendard II’s rather “fat” fuselage!

Indeed. I think a Whitcomb Body would be the way to go. I think wasp-waisting in such a limited length would be problematic. For illustrative purposes only!

 

[Archibald]

The Gabizo story remains to be told - and it would be quite interesting. Just like Dassault vs the SNCAs, Turbomeca and SNECMA had some "pact" not to compete with each other on gas turbines.
And just like the airframe duopoly, Turbomeca was the smart private company (with Joseph Szydlowski in the role of Marcel Bloch-Dassault) and SNECMA was the lumbering public company. Not too bright nor inspiring, but filling a nationalistic need so too big to fail.
The third (and sick) man (equal to Breguet) would have been Hispano Suiza, which manufactured RR engines in the 1950's before throwing the towel.

Sooo
-----------------------SMART PRIVATE--------BIG STATE OWNED-------SICK THIRD MAN

AIRFRAMES-----------Dassault----------------SNCAs - SNIAS-------------Breguet

ENGINES---------------Turbomeca------------SNECMA---------------------Hispano-Suiza

Next, and just like the airframe duopoly, at times there were "breaches" into the pact.

Gabizo was one such breach. Adour & Larzac were others. My personal opinion is that Turbomeca exceptional dynamism and success could have been a boost to SNECMA in their looooong quest to replace the Atar.

---------------------

In France Fights On timeline (POD: June 13 1940 in Tours-Cangiers: with Churchill present, Pétain is told to go fuck himself and consequently blow a gasket, dying a vegetable some weeks later. Reynaud grows a spine at least, De Gaulle's faction carries the day and... France fights on, after crossing the sea to Algiers. Vichy happens nonetheless with that dog Pierre Laval as the NEF (Nouvel Etat Français) , but scaled back to insignificance compared to OTL - as they are left only scorched earth, ruins and wrecks, the SOBs).

I had Szydlowski and his pal Planiol jumping from Algiers to exile in the USA; and from D-520 compressor to Lockheed P-38 turbocompressor; and from there, stumbling on the J37 / L-1000 extremely advanced design by Nathan Price (or Pryce, can't remember). Lockheed and Turbomeca then sealed an alliance and the J37 became Turbomeca crown jewel, making SNECMA Atar look a bit... outdated.
Imagine J37 derivatives selling like Turbomeca's OTL helicopter turbines: breaking the bank. SNECMA would have had kittens.

 

[Archibald]

All this to say that Turbomeca's Gabizo was a miserable failure, never worked properly. One of the very few engine Turbomeca ever got wrong.
BUT you could have Hispano Suiza taking a RB-153 licence - they got the Nene and Tay before that.

Rolls-Royce RB.44 Tay - Wikipedia

en.wikipedia.org

Hispano-Suiza - Wikipedia

en.wikipedia.org

the French arm of Hispano-Suiza continued primarily as an independent aerospace firm. Between 1945 and 1955, it was building the Rolls-Royce Nene under license, designing landing gear in 1950 and Martin-Baker ejection seats in 1955. The company's attention turned increasingly to turbine manufacturing and, in 1968, it was taken over and became a division of SNECMA.

 

[zen]

A licensee for early RB.153 has consequences for things like the Gnat MkV and later near complete revision of the RB.153 into a turbofan with MTU.

But a supersonic Etendard II or Gnat MkV results in some significant options to pursue.
Both of which rather act as precursors to the BAC P.45 that showed a lightweight aircraft could do a lot of roles.

We know Gnat MkV was offered with 2 Firestreak and AI.23.
A notional Etendard II-S (supersonic) might mount a Cyrano and a single R.530?
but a UK version might mount the same as Gnat MkV.....

And a variant might offer a CTOL backup to NMBR.3?

 

[Archibald]

and later near complete revision of the RB.153 into a turbofan with MTU.

Ah yes, that one has two lives. And from that RB.153 reworked into a turbofan stemmed the RB.172, also known as M45 (hello, SNECMA and AFVG and Dassault) - and from there, that scaled down variant for Jaguar, called Adour (here we go again, Breguet, ECAT).
And later the RB.199 / XJ-30/40 demonstrators / EJ200 family of engines.

In a sense, the turbofan RB.153 pioneered the "medium size turbofan" of F404/F414 fame that allowed the Hornet to happen at 2/3rd the size, weight and cost of a F-15. Same story later for the M88 and EJ200, Rafale and Typhoon.

I often think Rafale is to Mirage 4000 what the Hornet was to the F-15 for Australia, Spain and canada (among others). "If it is too big and expensive because of its pair of engines, then tries smaller engines, you dummy."

 

[H_K]

But a supersonic Etendard II or Gnat MkV results in some significant options to pursue.
Both of which rather act as precursors to the BAC P.45 that showed a lightweight aircraft could do a lot of roles.

It would have been really interesting to see these conventional swept wing designs evolve over time. Shame everyone declared those designs obsolete and chased after the variable geometry dream, which was great on paper but somewhat disappointing in real life.

 

[Archibald]

But a supersonic Etendard II or Gnat MkV results in some significant options to pursue.
Both of which rather act as precursors to the BAC P.45 that showed a lightweight aircraft could do a lot of roles.

It would have been really interesting to see these conventional swept wing designs evolve over time. Shame everyone declared those designs obsolete and chased after the variable geometry dream, which was great on paper but somewhat disappointing in real life.

Yup - from SMB-2 and Etendard it took Dassault a decade and VSTOL failure to go back to swept wing (F2 - F3 - F1, in THAT order) only to drop it for VG (G G4 G8) and then nearly another decade to return to swept wing (ACF) only to drop it for the "eurocanard" shape, 4000 first then Rafale.

Had things been logical, the ACF should have been called Mirage F8 (first because it was the high end to the F1-M53, and secondly because it was at core a fixed wing G8 - wings fixed at 55 degrees, an angle determined by the second G8 in 1974 - so what's the point of VG in the first place ? d'oh !).

But Dassault sucks at naming conventions and logic - as much as they excel at airframes (which says something !)

 

[zen]

Ok a minor resurrection.
Having looked at the E300, this might have solved the problem. Being roughly the right time.
Being 7,275lb dry and 10,580lb reheated.
Length 169"
Diameter 33"
Weight 1,896lb

 

[H_K]

The Atar with reheat would be too long, too heavy, and too thirsty for the Etendard. The CoG implications alone make it a non-starter, even before you start lengthening the rear fuselage, adding fuel tanks etc.

I’m going to quote myself from a year ago just to say that I’ve changed my mind. Playing around with the Atar 9B vs. Atar 8, I do think a reheated Atar was an option for the Etendard.

It would have been a big change, but the Atar 9B *might* have been moved forward to keep the CoG neutral. With more thrust and a slightly enlarged wing enabling a higher take-off weight, using the larger 1,100L (or even 1,300L) tanks as standard instead of small 600L tanks should have more than offset the extra fuel consumption in reheat and produced a comparable combat radius and performance to the Crusader.
https://www.secretprojects.co.uk/threads/dassault-etendard-prototypes-and-projects.11138/post-605395

Two pics below:
- First pic is the Atar 8 vs Atar 9B installation, keeping the aircraft center of gravity identical.

- Second pic is the original Etendard IV (top) vs. a supersonic Etendard (bottom). Changes include: 1) larger nose (for Cyrano radar), 2) raised canopy and spine to fit the longer Atar 9B with reheat above the main landing gear, and 3) fatter/longer tail to fit the reheat tunnel.

 

[Archibald]

I do think a reheated Atar was an option for the Etendard.

View: https://www.youtube.com/watch?v=NmPhaG1ud38

 

[Archibald]

Ok a minor resurrection.
Having looked at the E300, this might have solved the problem. Being roughly the right time.
Being 7,275lb dry and 10,580lb reheated.
Length 169"
Diameter 33"
Weight 1,896lb

I have big plans for the E-300 in my space TL. It is beyond me the Indians didn't salvaged the engine in June 1969, for the Marut (Kaveri, cough).
More troubling: now that we have the E-300 diameter - 33 inch - we can see it wasn't much wider than the Orpheus 700 series - 32.4 inch. Which is quite logical, as the HA-300 had been designed around an Orpheus. Yet the Marut-E.300, they said the E-300 did not fit: the area rule was botched and it had too much drag. Something is wrong there.
A Marut with two E-300 would have had more power than an Adour Mk.102 Jaguar, and perhaps even a Mk.104.

 

[Archibald]

Let the fun begin... I've put, side by side, specs of a few jet engines.

 

[zen]

H_K looks like the fusilage would have to stretch a little both ahead and astern the wing box.