Fulmar in 1941/42/43: feasible and/or plausible upgrades?

[RCAFson]

Let's be realistic; even a small increase in speed isn't going to make anything but a negligible difference to the Fulmar's combat capability (no one's doubting the kills made in it, but the Med was swarming with enemy aircraft). The Fulmar can be described as being the Boulton Paul Defiant of the FAA - without any derogatory connotations. Both were well designed and finely finished machines, which were easy to fly, but the concepts they were designed to were flawed in the face of modern combat scenarios. Another thing they both had in common was that there were very few of them in operation at any one time, facing overwhelmingly superior numbers of enemy aircraft. After a less than impressive innings as a day fighter (for which it was not designed - it was a bomber destroyer, not for fighter v fighter combat) The Defiant redeemed itself as a night fighter, but the fundamental problem with both types was that they were too slow, even after refitting with more powerful engines. This meant that both were always going to be replaced by better performing types. Both were also somewhat larger and heavier than their single-seat opposition.

Comparing the two, the Fulmar I was larger, heavier (9,800 lb loaded weight), had a shorter range (800 miles) and lower ceiling (26,000 ft) and was slower (280 mph, 1,200 ft/min rate of climb) than the Defiant I (8,240 lb AUW) (950 miles) (31,000 ft) (304 mph, 1,900 ft/min).

Fulmar figures from Fairey Aircraft since 1915; H.A.Taylor, Defiant figures from The Defiant File; Alec Brew.

Everything I've seen indicates a range of ~465 miles for the Defiant I with 103 gals of internal fuel however the Defiant II NF was modded in Aug 1941 to increase fuel capacity to 162 gals to increase patrol time as a NF.

 

[Shortround6]

I'll again call the Merlin 30 as 'Merlin 20 series with low supercharger gear only ', for the sake of comparison. The Hurricane IIC was making ~305 mph on low gear, ~325 on high gear, all at +9 psi boost. That's 7% increase in speed. 280 mph increased for 7% gives 300 mph, for the 'Fulmar III' (the hypothetical with Merlin 20 series).

And should we average that with the speed increase of the Defiant when it got the Merlin XX?

The Defiant II managed 313mph at 16,500ft, a wopping 9 mph over the MK I with the Merlin III. The Defiant was a smaller airplane than the Fulmar.

First "Protoype" Fulmar (actually first production plane, there was no true prototype, initial "prove of concept" had been done with a modified P.4/34 bomber) managed 230mph with a Merlin III uprated to 1080hp. With a lot of work to clean up the engine installation and the fitting of the Merlin VIII engine they got the speed up to 255mph. Fitting the Merlin 30 got the speed up to about 270mph but the planes also had tropical equipment fitted and extra radio equipment. (antenna's may cause more loss of speed than the weight??).

A Fulmar's "Tare" weight was heavier than a loaded Defiant. You are going to need a LOT of power to get the Fulmar up to even the performance of a Defiant. And that gets you what in 1942/43??

 

[tomo pauk]

I have 155 imp gals of fuel for the Fulmar, plus 60 IG in drop tank ('later aircraft carrying it' - the Fulmar II?), 104 IG for the Defiant F.1 and 159 IG for the Defiant F.2.
Range being 465 miles for the Defiant F.1, 550 miles for the F.2, and 830 miles for the Fulmar (with drop tank?). 'Search radius' for the Fulmar being 250/320 miles (DT absent/present), patrol endurance 4/5.5 hr (ditto).

 

[RCAFson]

For completeness, it was not an open sky encounter. It was an attack on a British convoy of five merchants, two carriers, two cruisers and nine destroyers (Operation Tiger). Due to bad wheater, that the British were taking advantage of, to avoid the chase of the Axis forces, the action of the Regia Aeronautica could begun only at 13:45, a time particularly unfavorable for torpedo bombers, who usually preferred to strike at dawn or dusk, to take advantage of the sun.
Italian records registered two (of six present) SM79 torpedo-bombers lost (Lt. Cappa and Cpt. Boetto), the first credited to the ships' defensive fire, and three Cr.42 for various reasons. In the action was shot down, by a Cr.42, the Fulmar of Lt. Rupert Tillard (Commander of the 808 squadron, fighter ace with 6.5 victories) and Lt. Mark Somerville, observer. Three other Fulmars were also damaged.

Don't know for the Germans, who attacked later, but I tend to believe that, even in this case, the fighters were responsible only for a part of the losses.

It was a confusing action but Shores notes the loss of 4 SM-79s and two Cr-42s and identifies the flight crews. He doesn't state any losses to AA although it does seem likely that one or more of the SM-79s were lost to AA as some did succeed in dropping their torpedoes. However none of the Luftwaffe aircraft made contact with the RN ships.

The engagement with the Me-110 is described as 3 Fulmars versus 6 Me-110s and 4 Fulmars versus 28 Ju-87s.

 

[RCAFson]

And should we average that with the speed increase of the Defiant when it got the Merlin XX?

The Defiant II managed 313mph at 16,500ft, a wopping 9 mph over the MK I with the Merlin III. The Defiant was a smaller airplane than the Fulmar.

First "Protoype" Fulmar (actually first production plane, there was no true prototype, initial "prove of concept" had been done with a modified P.4/34 bomber) managed 230mph with a Merlin III uprated to 1080hp. With a lot of work to clean up the engine installation and the fitting of the Merlin VIII engine they got the speed up to 255mph. Fitting the Merlin 30 got the speed up to about 270mph but the planes also had tropical equipment fitted and extra radio equipment. (antenna's may cause more loss of speed than the weight??).

A Fulmar's "Tare" weight was heavier than a loaded Defiant. You are going to need a LOT of power to get the Fulmar up to even the performance of a Defiant. And that gets you what in 1942/43??

In 1942 the only other folding wing Allied naval fighter was the F4F-4/Martlet/II/IV:
View attachment 231438
View attachment 231439
so I don't understand your fixation on the Defiant. However to be fair the Defiant II added a lot more weight for fuel and radar so an increase in speed is actually quite impressive and proves my point.

A Merlin 45 with 16lb boost should bring the Fulmar well past the Martlet in performance.

 

[tomo pauk]

And should we average that with the speed increase of the Defiant when it got the Merlin XX?

The Defiant II managed 313mph at 16,500ft, a wopping 9 mph over the MK I with the Merlin III. The Defiant was a smaller airplane than the Fulmar.

The Spitfire V earned 25 mph over Spitfire II, Merlin 45 vs. Merlin XII as we know all too well.
The Defiant was also lugging around the turret, unlike the Fulmar.

First "Protoype" Fulmar (actually first production plane, there was no true prototype, initial "prove of concept" had been done with a modified P.4/34 bomber) managed 230mph with a Merlin III uprated to 1080hp. With a lot of work to clean up the engine installation and the fitting of the Merlin VIII engine they got the speed up to 255mph. Fitting the Merlin 30 got the speed up to about 270mph but the planes also had tropical equipment fitted and extra radio equipment. (antenna's may cause more loss of speed than the weight??).

As you can see, I'm advocating the 2-speed Merlin to be installed, so our Fulmar can actually fly at 15-20000 ft, hence taking advantage of thinner air there. The 270 mph speed mark was reached between 5-10 kft?

A Fulmar's "Tare" weight was heavier than a loaded Defiant. You are going to need a LOT of power to get the Fulmar up to even the performance of a Defiant. And that gets you what in 1942/43??

It gets you somewhere in 1941, and certainly gets you more than with historical Fulmar.

 

[nuuumannn]

I agree, Shortround.

a range of ~465 miles for the Defiant I with 103 gals of internal fuel

...at a speed of 259 mph according to Boulton Paul Aircraft since 1915 by Alec Brew - same author as The Defiant File. The Defiant II's range is quoted as being 840 miles in The Defiant File, with a maximum speed of 325 mph, although he quotes 313 in trials with the A&AEE in the text. It'd be interesting to find out where Brew got his figures for the Defiant's range in The Defiant File. Other books I've got also quote 465 miles for the Defiant. (Well spotted) The Secret years; Flight testing at Boscombe Down 1939- 1945 (Tim Mason) quotes the Fulmar II's range as 980 miles, but has no range figure for the Defiant I. The II achieved 450 miles and with a best range speed of 162 mph achieved 5.65 air miles per gallon.

 

[nuuumannn]

The Defiant was also lugging around the turret, unlike the Fulmar.

Yet the Defiant was still faster than the Fulmar.

It gets you somewhere in 1941, and certainly gets you more than with historical Fulmar.

But not of any significance to make any appreciable difference compared to the real thing. Still far too slow and in need of replacement. It would have been a waste of effort to build a 'Fulmar III'.

 

[RCAFson]

But not of any significance to make any appreciable difference compared to the real thing. Still far too slow and in need of replacement. It would have been a waste of effort to build a 'Fulmar III'.

The Fulmar III/Merlin 45 could have been in production from mid 1941 and when approval for 16lb boost happens in Dec 1941 it becomes the best performing Allied folding wing fighter. Again the "competition" in 1942 was the F4F-4 or Martlet II/IV.

 

[tomo pauk]

Yet the Defiant was still faster than the Fulmar.

Of course.
Since the Defiant was not in service with FAA, even if it was making 400 miles it's speed is a moot point.

But not of any significance to make any appreciable difference compared to the real thing.

The real thing was, alas, the historical Fulmar. It was making maybe 250 mph at 15000 ft....

Still far too slow and in need of replacement. It would have been a waste of effort to build a 'Fulmar III'.

You probably weren't around when I started some threads refering to the possible/feasible FAA planes for the pre-1943 time, and I certainly was not sparing Fulmars for it's lack of performance. Unable to relaibly catch those pesky SM.79s and Ju-88s etc.
The Fulmar III should be faster some 50 mph at 15000 ft and above vs. Fulmar I/II, so it would certainly be no waste.

 

[Greyman]

The official 'Data Sheet' says:

permanent tanks (auxiliary tanks)

Fulmar I
Fuel Carried: 155 (215)
Fuel Allowance: 25 (25)
Range: 810 (1124)

Fulmar II
Fuel Carried: 155 (215)
Fuel Allowance: 25 (26)
Range: 795 (1070)

Defiant I
Fuel Carried: 162
Fuel Allowance: 20
Range: 950

Defiant II
Fuel Carried: 162
Fuel Allowance: 29
Range: 840

 

[tomo pauk]

Hello, Greyman, would it be possible to take a more compete look at the data sheets?

 

[FLYBOYJ]

A Merlin 45 with 16lb boost should bring the Fulmar well past the Martlet in performance.

Assuming that's done to a Fulmar II.

The Fulmar I had a Merlin putting out a little over 1000 hp, the II had a 1200 hp Merlin. The 45 Merlin puts out 1500 hp if I remember right. You're not bolting on that much more HP without strengthening the structure = weight. Would the same propeller be run as well?

I don't see getting much more of an improvement that would be cost effective in both manpower and maintenance over the Martlet.

In any recip of the WW2 era, putting an extra crewman on a "fleet fighter" was a waste of time and manpower.

 

[Shortround6]

The Spitfire V earned 25 mph over Spitfire II, Merlin 45 vs. Merlin XII as we know all too well.
The Defiant was also lugging around the turret, unlike the Fulmar.

Defiant with turret was only 15-25mph slower than a Hurricane with the same engine. Speed difference of the prototype Defiant without turret and versions with turret was under 10mph.

As you can see, I'm advocating the 2-speed Merlin to be installed, so our Fulmar can actually fly at 15-20000 ft, hence taking advantage of thinner air there. The 270 mph speed mark was reached between 5-10 kft?

True on were the speed was reached but then most of the attacking aircraft against the fleet/convoys were NOT at 15,00-20,000ft. Granted you can dive but that is only going to work once per attack.

It gets you somewhere in 1941, and certainly gets you more than with historical Fulmar.

Merlin XX is going to get you not much more than the Merlin 30 at low altitudes in 1941. When did the British allow the higher boost settings on the Merlin XX series engines?

The Italian engines had critical altitudes of between 3800-4200 meters for the most part. They were in no hurry to try to fight at 20,000ft.

The Merlin 30 was pretty much a Merlin XII with a cut down impeller ( 9.75in) and using the same supercharger gear as a Merlin III.

Tip speed was almost identical to the tip speed of a Merlin XX in low gear.

It did NOT have the improved Hooker designed supercharger inlet.

Fitting the Hooker designed inlet, some internal strengthening ( you can't just jack the boost on the early engines to what ever you want) and the engine was cleared for 18lbs boost as the Merlin 32 used in the Barracuda. 1640hp at 2000ft is as good as it is going to get for chasing torpedo bombers.

 

[Dogwalker]

It was a confusing action but Shores notes the loss of 4 SM-79s and two Cr-42s and identifies the flight crews.

Who were they?

However, according to the report of "Royal Navy Aces of World War 2", it doesn't seems to me that the Fulmar had a so good day. Against a small group of low flying SM.79s burdened by torpedoes and escorted by Cr.42s (hardly the best escort you can encounter in mid 1941) they had two losses and a badly wounded TAG first to get their first strike.

 

[RCAFson]

The official 'Data Sheet' says:

permanent tanks (auxiliary tanks)

Fulmar I
Fuel Carried: 115 (215)
Fuel Allowance: 25 (25)
Range: 810 (1124)

Fulmar II
Fuel Carried: 115 (215)
Fuel Allowance: 25 (26)
Range: 795 (1070)

Defiant I
Fuel Carried: 162
Fuel Allowance: 20
Range: 950

Defiant II
Fuel Carried: 162
Fuel Allowance: 29
Range: 840

These numbers are wrong for the Fulmar. Numerous sources (including the pilot's notes) state 155 Gals of internal fuel and a 60 gal DT. Defiant I was later modded to carry 162 gals, but this was not on production Defiant Is.

 

[RCAFson]

Who were they?

However, according to the report of "Royal Navy Aces of World War 2", it doesn't seems to me that the Fulmar had a so good day. Against a small group of low flying SM.79s burdened by torpedoes and escorted by Cr.42s (hardly the best escort you can encounter in mid 1941) they had two losses and a badly wounded TAG first to get their first strike.

There was also small numbers of Fulmars. Shores gives the last names of the downed SM-79 pilots as Cappa, Marini, Boetto and Fonseca. Two Cr-42s were lost as well.

 

[tomo pauk]

Defiant with turret was only 15-25mph slower than a Hurricane with the same engine. Speed difference of the prototype Defiant without turret and versions with turret was under 10mph.

Okay; the 1st prototype was not fitted with back-facing exhausts, that should cost some speed. The second prototype received turret?

True on were the speed was reached but then most of the attacking aircraft against the fleet/convoys were NOT at 15,00-20,000ft. Granted you can dive but that is only going to work once per attack.

Fulmar will never be a true performer, so the ability to dive to the prey from 15000 ft, with decent amount of built-up speed will come in handy. One might use up the speed to make a zoom climb, too.

Merlin XX is (NOT) going to get you not much more than the Merlin 30 at low altitudes in 1941. When did the British allow the higher boost settings on the Merlin XX series engines?

My addition in the brackets
Seems the +12 psi was the limit prior late 1942, later increased to +14 in low gear and +16 in high gear.

The Italian engines had critical altitudes of between 3800-4200 meters for the most part. They were in no hurry to try to fight at 20,000ft.

That would mean 13-14000 ft, ie. just down the patrolling 'Fulmar III'?

The Merlin 30 was pretty much a Merlin XII with a cut down impeller ( 9.75in) and using the same supercharger gear as a Merlin III.

Tip speed was almost identical to the tip speed of a Merlin XX in low gear.

It did NOT have the improved Hooker designed supercharger inlet.

Thanks for corrections

Fitting the Hooker designed inlet, some internal strengthening ( you can't just jack the boost on the early engines to what ever you want) and the engine was cleared for 18lbs boost as the Merlin 32 used in the Barracuda. 1640hp at 2000ft is as good as it is going to get for chasing torpedo bombers.

The Merlin 32 should give indeed more oomph, but we still need to wait until 1943/43?

 

[Dogwalker]

Shores gives the last names of the downed SM-79 pilots as Cappa, Marini, Boetto and Fonseca.

This is from the Historical Office of the Aeronautica Militare (in Italian, sorry).

"Missione del 8 maggio 1941 Il 7 maggio 1941 la squadriglia è messa in allarme. Vengono caricati i siluri su tutti gli apparecchi e si rimane pronti a partire. Il giorno successivo a mezzogiorno 5 velivoli partono su allarme all'attacco di una formazione navale inglese composta da una nave portaerei (HMS Ark Royal), 2 navi da battaglia, un numero imprecisato di incrociatori e cacciatorpedinieri e 10 piroscafi. Sul numero 2 il comandante di squadriglia Cap. Mojoli con Bellesia, Bucci, Picco, Monaco e Principe, il numero 3 ha come equipaggio Magagnoli, Santi, Conti, Grassi, Palù e Panato, sul numero 1 Rivoli, Segoni, Cerasa, Becciu e Artoni, sul velivolo 4 Marini, Marengo, Bevacqua, De Nardi e Ruscica. Sul velivolo n. 5 il ten. Cappa con Giovagnoli, Flamini, Scafa e Luciani. L'obiettivo è segnalato in Lat. 35°, 45' N, Long. 7°, 25' E, viaggia a circa 20 miglia orarie in direzione 90°. La testa della formazione navale è avvistata sulla dritta da distanza di 30 km a quota 25-300 metri. Gli aerosiluranti usciti dalla zona temporalesca dei primi 40 minuti di volo a bassissima quota (nubi basse, piovaschi e banchi di nebbia) entrano improvvisamente in zona sgombra con nubi alte copertura parziale e visibilità ottima. Si rileva subito che la rotta della formazione navale non è più di 90° ma di circa 70°. Questa variazione di rotta è certamente stata effettuata dalla formazione navale per portarsi ai margini della zona temporalesca onde avere un'ottimo occultamento ed effettuare il lancio di tutti gli aerei da caccia con vento in prua alla nave portaerei. All'attacco, infatti, le unità del lato opposto (nord) dello schieramento risultano non ben visibili trovandosi già nella zona di foschia. La formazione entra a 10.000 metri su di un beta generale di circa 70° rispetto alla formazione con convergenza sulla portaerei, a volo rasente (metri 3) pronta ad allargarsi alle prime salve in acqua. A 8000 metri inizia da parte delle navi lo sbarramento in acqua che risulta piuttosto corto (colonna d'acqua dei grossi calibri delle corazzate). La formazione si allarga cabrando fino a 200 metri. Lo sbarramento è nutrito e concentrato nel settore di avvicinamento alla portaerei. Tutte le unità, anche dal lato opposto, aprono il fuoco. Gli aerosiluranti sono completamente inviluppati dal fuoco contraereo dei cannoni e delle mitragliere. Il capo formazione giudicato non superabile lo sbarramento per giungere a distanza utile di lancio contro la portaerei trovandosi a quota superiore rispetto ai gregari di sinistra, vira sulla sinistra occupando così la posizione esterna sinistra della formazione attaccante: sicchè detta formazione risulta una leggera "ala destra". La manovra è rapidamente avvertita dagli altri equipaggi come il segnale di attacco al bersaglio immediato più opportuno (come contemplato nel 3° caso di previsione) che automaticamente si determina sulla linea degli incrociatori che dista ormai di circa 2500-3000 metri.Questa manovra porta su un beta ottimo di lancio tre apparecchi: il 1° di sinistra sull'incrociatore arretrato rispetto alla portaerei;i due esterni di destra (Cappa è gregario destro) su due incrociatori avanzati; Dei due interni - in una zona libera nella linea di fila degli incrociatori: Uno decisamente diretto all'attacco della portaerei viene abbattuto. L'altro supera la linea degli incrociatori interni ed attacca il piroscafo in prua alla portaerei. (Secondo gli appunti del comandante della squadriglia, cap. Mojoli, il velivolo di Cappa fu abbattuto dal fuoco della portaerei Ark Royal). La manovra di disimpegno per i tre apparecchi (attaccanti gli incrociatori) si è definita migliore con una controvirata con violenta cabrata sfilando a poppa della formazione navale. L'apparecchio attaccante il piroscafo di prua alla portaerei (e quindi al centro dello schieramento) ha trovato opportuno disimpegnarsi sfilando di prua allo schieramento per evitare di ripassare sulla linea degli incrociatori e dei cacciatorpediniere."

Fonseca is not listed, four SM.79, of five, escaped. Marino Marini came back from that mission, continued to fight throughout the war (became the Commander of the torpedo-bombers group "Buscaglia"), and died in 1959.

As for Armando Boetto:
"L'8 maggio 1941 lo Stormo attaccò, nonostante le pessime condizioni meteo, un grosso convoglio, ... . Un velivolo partì col compito di fare da radiofaro: il capo equipaggio, Cap. Armando Boetto, non rientrò e alla Sua memoria venne conferita la Medaglia d'Oro al Valor Militare "sul campo"."
Probably the lone SM.79 that Lt. Ronnie Hay claimed off Galita Island.

 

[Shortround6]

In any recip of the WW2 era, putting an extra crewman on a "fleet fighter" was a waste of time and manpower.

what is seldom discussed is the 2nd crewman, often called the radio operator, as part of his equipment had a radio receiver that could find a signal transmitted from the carrier and home in on it, guiding the plane back to the carrier. He was NOT a 'navigator'. The British homing system was 'supposed' to be not interceptable by the enemy and give away the carriers location like a normal "homing system".