WesWorld

First, sorry for my intermittent activity. Life has a way of getting crazy sometimes when you work two jobs. Anyhow, Brock's threads got me thinking about how I am thinking of Italian jet fighter (and bomber eventually) development will progress. I'm going to detail some of my thoughts and rough stats for the first few types to see service. As for background, Italy has been extensively testing motorjets for the past three years (give or take a few months) and the first Italian built jet flew in early 1944 on a modified motorjet airframe. I have little details on the engine, but am assuming it and subsequent engines follows the developmental line that would allow the thrusts necessary for the following aircraft.

The first designed from the ground up jet, and jet fighter to see prototype testing. Never enters combat service, tho data gathered during its testing is invaluable going forward. Test fights in early 1945, program officially ends in 1946 but the airframes are used in various testing rolls for longer.

General characteristics
Crew: 1, pilot
Length: 9.5 m
Wingspan: 8.00 m
Height: 2.5 m
Powerplant: Turbojet in the 1600 lbf class

Performance
Maximum speed: 825 km/h
Range: 490 km
Service ceiling: 10,000m

Armament (planed)
4x20mm Cannon

Having much more practical experience, Caproni opts for a twin engine design for its first dedicated jet fighter. Despite its later introduction, this plane wins the approval of both the Italian Air Defense Force and the Marina Militare. It will see mostly land-based service, but it will also be the first Italian jet to land on a carrier. Later variants and developments of the type and design linage will be the first Italian carrier based jet fighters. First flight in mid-late 1945, service adoption in several squadrons early-mid 1946, phased out to training rolls by 1949

General characteristics
Crew: 1, pilot
Length: 9.75 m
Wingspan: 10.50 m
Height: 3 m
Powerplant: Two turbojets in the 1600 lbf class

Performance
Maximum speed: 880 km/h
Range: 825 km
Service ceiling: 12,000m

Armament
2x20mm Cannon
2x250kg hardpoints (plumbed)

With time, more powerful single jet engines surfaced and Fiat would take advantage of there early testing with the Cometa and create the first widely accepted jet fighter. While it was confined manly to interceptor duties, it was the first time a jet would compleatly dislocate the famed G.55 from a service nitch. First flight in early 1947, service adoption later that year. Would remain in service in a variatry of roles until the mid 1950's, with specialized trainer variants lasting much longer.

General characteristics
Crew: 1, pilot
Length: 8.5 m
Wingspan: 9 m
Height: 3 m
Powerplant: Turbojet in the 2400 lbf class (later 2600 lbf)

Performance
Maximum speed: 910 km/h
Range: 600 km
Service ceiling: 12,000m

Armament
2x20mm Cannon (later 4)
2x250kg hardpoints (plumbed, later 4 hardpoints)

The first Italian jet designed from the start as a carrier-based fighter. Built on the Cinghiale's design principals, the basic airframe (inclusive of all upgraded and specialized variants) would see active shipboard service from almost 25 years. As the variants have a clear divider between the strait and swept wing versions, the strait wing variant is detailed here. First flight in early 1948, carrier trials later that year. Service adoption late 1949. Phased out starting in 1955.

General characteristics
Crew: 1, pilot
Length: 10.75 m
Wingspan: 11.5 m
Height: 3.75 m
Powerplant: Two turbojets in the 3000 lbf class

Performance
Maximum speed: 910 km/h
Range: 1800 km
Service ceiling: 13,000m

Armament
4x20mm Cannon
2x500kg hardpoints (plumbed, later 4 hardpoints)

Sucessor to the Fantasma, this is the jet that spells the death knell for the G.55 as the frontline fighter. The Spettro's first flight is in very late 1949, service adoption in mid 1950. The type continues to see service until the 1970s. Note this is a slightly tweaked version of the historicalFiat G.80 series done as a single seat fighter. The historical trainer version will also be built, and will also be the basis for several specialized aircraft.

General characteristics
Crew: 1, pilot
Length: 12 m
Wingspan: 11.8 m
Height: 4 m
Powerplant: Turbojet in the 5000 lbf class

Performance
Maximum speed: 910 km/h
Range: 1250 km
Service ceiling: 13,000m

Armament
4x20mm Cannon
4x500kg hardpoints (plumbed)

General comments:

In outlining the designs, it would be very helpful if the weights were specified as well as dimensions; it would help in forming an opinion whether the aircraft could attain the performance with the engine specified.

The biggest problem to overcome is in terms of backstory - historically Italy has never been successful with indigenous turbojet designs - most of its aircraft used foreign engine designs well into the 1970s. I think you need to demonstrate the progression of engine designs to account for this. The moto-jets are a design dead end, and I know that you have announced the first tests of true turbojets - so a bit more background in this area would be appreciated.


Fiat Cometa

Not an unreasonable design for the information presented; the general caveat of whether the engine has enough thrust applies, so beyond a general - "sounds okay" I cannot say much. Does this aircraft have an OTL counterpart or something you had in mind?


Caproni Cinghiale

Hmm. Just when did development work on this aircraft begin? Obviously some time before 1945 by how long? The development cycle seems as though it could be on the short side, depending on when the work began; first-generation aircraft would be expected to have a lengthy design cycle. The general caveat on weight applies. Likewise, is this designed inspired by anything in particular? Straight-wing or moderate sweep? If the latter, where did you gain the design experience?


Fiat Fantasma

Here I really would like to see more detail before making a definitive statement. The engine seems a bit on the weak side to me, but then, you haven't specified the aircraft's weight.


Caproni Calamaro

Here you have presented a straight-wing version of an aircraft that will eventually morph into a swept-wing variant, rather like the Grumman Panther/Cougar, expect that this design is twin engined. Again, I am having doubts about the thrust-weight ratio.


Fiat Spettro

As a clone of the G.80 series with that type of engine, I think you might actually be understating the performance you could expect.


If you can provide any further information on the designs or historical exemplars, I could speak in more detail.

Aircraft weight is one of those things I am not sure about. I figured it would be possible to figure out weight (or at least a rough approximation of such) from the listed preformance. If this is more trouble, weights in line with compatible historical types can be chosen and the designs tweaked from there.

The engines themselves are another thing I am not so sure about. I know that I want the engines to be home-grown, and RA mentioned in a thread that some work was taking place as far back as 1940, tho I have yet to find any references to early work. (Admittedly, I have not looked much) Part of my feelers here is to get an idea about the characteristics of the engines necessary so I can flush out the development of the engines further. As I said in the OP, "assuming [the 1944 engine] and subsequent engines follows the developmental line that would allow the thrusts necessary for the following aircraft." Aside from that, I can say that these are Fiat designed and built engines, but other companies may be licences to build copies.

Cometa: Glad it looks reasonable. I was thinking about something that could have been an early MiG, LaGG, or YaK prototype, but really any very early single engines jet would do.

Cinghiale: Given Caproni's major role in motorjet and early turbojet testing, it is possible that this aircraft has its roots back in about 1943 or late 1942. I would venture to say the decision to stick with two engines could be from originally thinking that a single engine would not produce sufficient power for a airframe to take flight, therefor requiring a second engine. When flight worthy engines did become available, the airframe was vested in having two engines despite that the all the jets the flew in Italy before this were single engine planes.

Fantasma: This would be a evolution of the Cometa, so the final figures for that aircraft greatly influence this one, as well as typed planed for WW and OTL introduction in the 1946-48 window. Its supose to be a bridge design between the Cometa and the Spettro, and I think the abilities should lie almost even between the two.

Calamaro: The Canadian gave me permission to base the aircraft on the Panther/Cougar. Given the necessary differences between single and twin engine aircraft, I did not think that using the Panther's weight was appropriate, tho it would be a good place to start.

Spettro: There are two reasons I went with depressed preformace figures. The first is that the Spettro carries heaver armament then the historical G.80 Second is that the historical G.80 first flew in 1951 not 1949, therefor I felt is was appropriate for the first version of the aircraft to have lower capabilities.

All of these stats are very preliminary and I am more then happy to adjust them to make the aircraft more realistic.

Thanks for the additional information, but without even approximate weights, it is difficult to even consider if the performance can be attained on the engine thrust specified.

While I do not think that there is a direct and fixed relationship of thrust/weight to speed, it does give an approximate idea of possible/impossible.

Ok, then lets try this. Seeing as I have good historical disigns to draw from for the Spettro (G.80) and Calamaro (F9F Panther), Im going to work backwards from there.

Spettro: 6255kg Gross (4400kg Empty)

Calamaro: 6400kg Gross (4220kg Empty)

Fantasma: 3000kg Gross (2200kg Empty)

Cinghiale: 4900kg Gross (3350kg Empty)

Cometa: 2800kg Gross (2000kg Empty)

I have taken the liberty of making some very rough calculations of the thrust-weight ratios of the Italian jet aircraft set before us, and of their OTL contemporaries. While the thrust-weight ratio is not a be-all-and-end-all, it does give me, at least, a rough order estimate of whether the aircraft's performance is plausible or implausible.



I also compared the gross weights (or closest approximation available to me) of the Italian proposals and their OTL contemporaries; I did this to obtain a rough-order estimate of whether an aircraft of given performance might be reasonably expected to have a particular gross weight.

The Cometa design, with its single engine, has a thrust-weight ratio in the range of the OTL He162 and YaK-15, even if its T/W is 0.26 compared to 0.29 for the He162 (which it matches for weight) and 0.34 for the Yak-15 (which is lighter). The Cometa design features a higher maximum speed with lower engine power, which leads me to conclude that the projected performance is above what one could reasonably expect.

The Fantasma design features a much more powerful engine, and the calculated T/W ratio of 0.36 is impressive. However, when comparing its 3,000 kg gross weight to its OTL contemporaries, it seems quite light, only 200 kg heavier than the Cometa. I think its weight is implausible, and on that count, the thrust-weight ratio obtained would have to be adjusted before a proper assessment of its performance made.

The Cinghiale design, a twin engine aircraft, seems plausible, if one assumes that its engines are carried in the fuselage - which would make it comparable with the OTL MiG-9. In gross weight and in T/W the Cinghiale compares well with the MiG-9, and the projected performance seems plausible. However, if the Cinghiale were laid out like the Gloster Meteor or Me262, its mass is far too low - which would change the assessment of its performance; a better description of the design's layout would help with useful feedback.

The Spettro design, based on configuration of the Fiat G.80, seems much lighter than the comparable F-80C, which is nearly 1,400 kg heavier. I find that implausible, and thus must question the projected performance.

The Calamaro design, which you have indicated is based upon the Grumman F9F, looks plausible except that you have stated that it has two engines, compared to the F9F's single engine; I do not think you have sufficiently allowed for the weight of the second engine and the structure required to support it. The twin-engined McDonnell F2H had a loaded weight of 9,531 kg, compared with the F9F's 6,456 kg, and the Calamaro's 6,400 kg gross weight. I think you need to re-examine the weight of this design and reconsider its probable performance.

First, thanks for doing that table. Very helpful. So adjusting a few things...

Cometa: Thets knock about 50kph of the speed and make it 775kph. That looks to be closer in line with the He162.

Fantasma: On looking, I think this needs both a speed and weight adjustment. I think adding 750kg to bring to gross weight to 3750kg (empty 2950kg) and adjusting the speed to 890kph is more reasonable and brings it closer in line to the Vampire.

Cinghiale: Yes, the layout would have both engines tucked in the fuselage ala the MiG-9 and P-59.

Sperrto: The figures for this aircraft are very close to the historical G.80, going from the stats listed on Wikipedia backed up by stats from the book "Una vita per l'Aviazione" by Giuseppe Gabrielli himself. I feel that given this is a single seat fighter over a two seat trainer that the difference in armament weights are close enough that similar to the histroical G.80 figures can be expected. I would further note that the range of the Sperrto (at least the early version defined here) is less then the G.80 by 250km. I would further note that the F-80C, while heaver, has a more powerful engine and is capable of 55kph faster top speeds by the information in the table you provided.

Calamaro: The F2H is a much better approximation of what I am looking for. An increase in weight to 9500kg gross (6000kg empty) is correct given the F2H's similarities to the intended layout and design choices of the Calamaro. That being said, an increase in range to ~2100km and a increase to 4 500kg hardpoints from the start (with two more added later for 6 in total) is also in order IMO, as those are more in line with the historical F2H which had a first flight a full year earlyer OTL then the Calamaro will have in WW.

Bruce's data certainly is a good starting point and your changes look along the right lines.

It looks like your developing three engines during the 1940s (1,600lb, 2,400-2,600 which might stretch to 3,000lb and the 5,000lb). That seems reasonable given Italy's engine capacity.
Whether these are axial or centrifugal will further alter things. I would say the 2,400, 2,600 and 3,000lb engines would have to be axials to allow twin internal engines and the 5,000lb would also be best as an axial, probably being developed into 6,500-7,000lb and more for the 1950s. The 1,600lb could be centrifugal to make max use of turbocharger know-how and speed development.

Quoted

Originally posted by Hood
Bruce's data certainly is a good starting point and your changes look along the right lines.

It looks like your developing three engines during the 1940s (1,600lb, 2,400-2,600 which might stretch to 3,000lb and the 5,000lb). That seems reasonable given Italy's engine capacity.
Whether these are axial or centrifugal will further alter things. I would say the 2,400, 2,600 and 3,000lb engines would have to be axials to allow twin internal engines and the 5,000lb would also be best as an axial, probably being developed into 6,500-7,000lb and more for the 1950s. The 1,600lb could be centrifugal to make max use of turbocharger know-how and speed development.

I'm not sure the engines would have to be axials in order to fit in a twin internal arrangement: the P-59 shows it can be done with centrifugal turbine engines as well. Though didn't the MiG-9 have centrifugal turbojets, too? (Not presently able to wiki things to check.)

A bit hard to comment given lack of data, or a means to differentiate between what's here. All of the figures posted so far could be done with centrifugal engines, though the final versions, up towards 5000lbf, would be reaching the max end of the scale.

Given the final end-state of the Spettro / G.80, which had a centrifugal Nene engine, I'd almost urge you to develop primarily a centrifugal turbojet in order for that final 5000lbf engine to match the Nene. Axial engines are a lot tougher to get right, and more severely challenge the materials science of the period, particularly in regards to metallurgy. (France is only developing a single axial engine in this decade, and only because they're getting design data from Germany and Atlantis, the design leaders for axial development in Wesworld). I could see Italy understanding that the axial will eventually work better, but accepting the downsides of the centrifugal turbojet engine in order to lower project development times, lower production costs, and get better performance on the front end of the development cycle. (Axial engines take a long time to pan out, as Germany's experience shows.)

Might I make the suggestion to use some designations, even temporary ones? Perhaps this might help (borrowed from what information I can see):
- T1600: Centrifugal/axial turbojet, 1600lbf, used in the Fiat Cometa and the Caproni Cinghiale. First tested late 1943, produced mid 1945.
- T2400: Unknown (centrifugal/axial) turbojet, 2400lbf, used in Fantasma. First run 1945, production mid 1947.
- T3000: Unknown (centrifugal/axial) turbojet, 3000lbf, used in Calamaro. Possible U-2400 upgrade?
- T5000: Unknown (centrifugal/axial) turbojet, 5000lbf, used in Spettro. Possible U-2400 upgrade?

Thanks for the reply Hood. With your suggestions in mind, how does this sound for engine development? Im going to list them by first flight, with the assumption that development took about two years for developmental upgrades and three years for scratch designs (WAGed figures, please correct me if these seam honorably out of line ether way). Designations are preliminary.

1944: Fiat C.1600 Italy's first turbojet, a centrifugal design. Used in the Fiat Cometa, Caproni Cinghiale, and other first generation jet propelled aircraft.

1946: Fiat A.2400, A.2600 and Alfa Romeo A.3000 First Axial turbojet design. Fiat designed and built, licensed production and modification by Alfa Romeo. First flown on a modified Cometa near the end of the program. Variants power the Fiat Fantasma, Caproni Calamaro, and other aircraft of the second generation.

1948: Fiat A.5000 Second generation axial turbojet. Original and upgraded variants used on third generation aircraft such as the Fiat Spettro. Upgraded and more powerful versions of this engine will power fourth generation aircraft (historical G.91 as example) and fly in 1950. Alfa Romeo and Isotta-Fraschini will build licensed copies and own-modification versions of this design, but they will mostly come after 1950.

Edit: Brock posted just before I did. The 2400lbf engine and the 2.6k and 3k modifications could be ether centrifugal or axial. I would like the 5000lbf engine to be an axial however. If it ends up as the only axial, it will fly in test aircraft in 1947 as opposed to 1948 but still not see service on a combat aircraft until 1949 on the Fiat Spettro. This is because I want to do a very very close copy of the historical G.91 (tweeked to follow the Spettro in some aspects) and that used a axial engine.

Edit #2: The MiG-9 used axial flow engines.

The P-59 is the only twin centrifugal jet-fighter I can think of. It had its engines in the wing roots and with the jetpipes behind the wing trailing edge. The F2H mentioned earlier in the thread had axial J34s. The MiG-9 had axial RD-20s (BMW 003). Most large centrifugals like the Nene had widths occupying the full fuselage width, fitting two might be possible with a staggered layout a la early Su-15 (which had large axials). My copy of Tony Buttler's British Secret Projects: Jet Fighters since 1950 has lots of 1946-1947 era twin jets but all have the AJ.65 which became the Avon. I think that's some indication how quickly the centrifugals were dropped and why the Nene and reheated Tay never found use in RAF jets.

I can buy the C.1600 and A.2400, A.600 and A.3000 series snip proposed. The A.5000, as Brock says it is early for such a powerful axial jet but British developments show it is possible. The Rolls-Royce AJ.65 was in development in 1945 and began testing in 1948 rated at 6,000lbs. Not until 1949 was it in production and producing the intended 6,500lbs. Design of the Armstrong-Siddeley Sapphire started in 1943 and entered testing around 1947, developing about 7,500lbs thrust. It took a few years before the production engine appeared. The Lyul'ka TR-3 qualified in January 1950 at 10,141lbs thrust. I'm not so up on US jets but it seems lager axials didn't appear until the early 1950s (one reason why Wright attempted to licence-build the Sapphire as the J-67). So could Fiat do this? If they have built three developed engines sharing many systems in the A.2400-3000 then it might be possible. Snips edited A.5000 timeline might work best.

Also snip, have you looked at the Aerfer Sagittario 2? A lightweight fighter that looked sleek, didn't fly until 1956 but had a Rolls-Royce Derwent but was supersonic. Might be something to look at for the 1950s with an axial jet. The follow-on was a jet-rocket hybrid.

Another solution could be this, make the A.2400 and A.2600 both centrifugal engines (C.2400 and C.2600) and keep the A.3000 as an axial but make it a early version of the A.5000. I would add a prototype engine of ~2000lbf that would fly in 1945, maybe this would be used on late mark Cinghiale fighters. This means that the carrier fighter can keep its axial engines and that the development linage is there to be able to build the A.5000 before 1950. The modified lineup is presented below.

1944: Fiat C.1600 Italy's first turbojet, a centrifugal design. Used in the Fiat Cometa, Caproni Cinghiale, and other first generation jet propelled aircraft.

1945: Fiat A.2200. First generation axial tubojet to see a full flight testing program. Design and development work undertaken starting in 1941. Serves as a jumping off point for the A.3000. Some versions of C.2400/2600 powered aircraft might see later marks with these engines.

1946: Fiat C.2400, Alfa Romeo C.2600 Second centrifugal turbojet design. Fiat designed and built, licensed production and modification by Alfa Romeo. First flown on a modified Cometa near the end of the program. Variants power the Fiat Fantasma and other aircraft of the second generation.

1947: Fiat A.3000 and Isotta-Fraschini A.3250 Second generation axial tubojet. More powerful development of the A.2200. Variants power the Caproni Calamaro and other aircraft of the second generation.

1949*: Fiat A.5000 Third generation axial turbojet. Original and upgraded variants used on third generation aircraft such as the Fiat Spettro. Upgraded and more powerful versions of this engine will power fourth generation aircraft (historical G.91 as example) and fly in 1950. Alfa Romeo and Isotta-Fraschini will build licensed copies and own-modification versions of this design, but they will mostly come after 1950.

1949: Alfa Romeo C.3000 Further development of the centrifugal line, is not adopted in third generation fighters due to the more powerful A.5000 being available. Sees use as a upgrade to centrifugal engined airframes and on use in second-line and civilian aircraft.

*Note this date pushes the Sperrto's first flight back into early 1950 as oppose to late 1949.

Thoughts?

Updated Stat lines for the aircraft in question


General characteristics
Crew: 1, pilot
Length: 9.5 m
Wingspan: 8.00 m
Height: 2.5 m
Powerplant: Fiat C.1600 turbojet (1600 lbf thrust)
Empty Weight: 2000kg
Gross Wieght: 2800kg

Performance
Maximum speed: 775 km/h
Range: 490 km
Service ceiling: 10,000m

Armament (planed)
4x20mm Cannon


General characteristics
Crew: 1, pilot
Length: 9.75 m
Wingspan: 10.50 m
Height: 3 m
Powerplant: Two Fiat C.1600 turbojets (1600 lbf thrust each)
Empty Weight: 3350kg
Gross Wieght: 4900kg

Performance
Maximum speed: 880 km/h
Range: 825 km
Service ceiling: 12,000m

Armament
2x20mm Cannon
2x250kg hardpoints (plumbed)


General characteristics
Crew: 1, pilot
Length: 8.5 m
Wingspan: 9 m
Height: 3 m
Powerplant: 1946: Fiat C.2400 (later Alfa Romeo C.2600, stats TBD)
Empty Weight: 2950kg
Gross Wieght: 3750kg

Performance
Maximum speed: 890 km/h
Range: 600 km
Service ceiling: 12,000m

Armament
2x20mm Cannon (later 4)
2x250kg hardpoints (plumbed, later 4 hardpoints)


General characteristics
Crew: 1, pilot
Length: 10.75 m
Wingspan: 11.5 m
Height: 3.75 m
Powerplant: Two Fiat A.3000
Empty Weight: 6000kg
Gross Wieght: 9500kg

Performance
Maximum speed: 910 km/h
Range: 2100 km
Service ceiling: 13,000m

Armament
4x20mm Cannon
4x500kg hardpoints (plumbed, later 6 hardpoints)


General characteristics
Crew: 1, pilot
Length: 12 m
Wingspan: 11.8 m
Height: 4 m
Powerplant: Fiat A.5000
Empty Weight: 4400kg
Gross Wieght: 6255kg

Performance
Maximum speed: 910 km/h
Range: 1250 km
Service ceiling: 13,000m

Armament
4x20mm Cannon
4x500kg hardpoints (plumbed)

All things considered, this is a far more believable picture than the one originally presented; the performance projections match the engine performance better, and some of the optimistic performance projections have been revised downward; the timeline has also been stretched to match the probable march of engine development.

I agree, these specs look much better now.