A WW2 fighter design for rugged areas

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Pasoleati

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A fighter for rough conditions for low and medium altutudes
Specs:
-R-1820 H-series with water injection (1475 hp)
-wing area perhaps around 19-20 sq.m.
-Fowler flaps with a maneouver setting actuaed by a stick switch
-fuel load some 600 litres
-armament 2 x 20 mm cannon
-undercarriage suitable for fields

I began thinking this idea after pondering two issues:
1. The Finnish Myrsky development was hampered by the indecision between speed and turn and in VL's designers' limited minds it was basically a question of wing area, no consideration being given to e.g. efficient manoeuvre flaps.
2. In Finnish service the availability rates of aircraft was much higher with air-cooled radials vs. liquid-cooled ones.
3. Ruggedness of general construction is of great importance. Especially that of the undercarriage.
 
Dilandu said:
Erm, you basically described the Soviet Yak fighters.
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In theory. But they lacked the flaps I mentioned and apparently at least the Yak-3 (which achieved it's performance through small size) had bad stalling characterics in turn.
 
Your suggestions parallel my suggestions about a Grumman Martlet/Wildcat armed with a single 20mm auto-cannon on the RCAF ‘46 thread.
 
Pasoleati said:
Nope, poor range.
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Poor range because of a thirsty M-82?
Encyclopedia of Soviet fighters 1939-1951 by Herbert Leonard, Histoires & Collection 2005 gives 125 gallons as fuel capacity for La-5FN, which had a 1850 hp fuel-injected M-82FN.
The Complete book of Fighters by William Green and Gordon Swanborough, Smithmark/Salamander 1994 gives 765 km range for La-5FN, 990 km range for La-7. What range do you have in mind?
I have to admit the two-row, 14-cylinder M-82 is a different beast than the R-1820.
 
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How much does 'rough/short field' landing gear track carrier aviation needs ??

Bigger wheels, longer 'oleos' etc ?? And, d'uh, preferably a stall speed to rival a briskly pedalled bicycle...
 
Nik said:
How much does 'rough/short field' landing gear track carrier aviation needs ??

Bigger wheels, longer 'oleos' etc ?? And, d'uh, preferably a stall speed to rival a briskly pedalled bicycle...
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There is some overlap between carrier-capable airplanes and airplanes designed for rough fields. They both need to touch down as slow as possible in minimize ground-roll. Carrier-capable landing gear already has long-stroke oleos to absorb high sink-rate touch-downs.
You just need to add wider tires to prevent them from snagging on ruts or sinking into soft sand.
 
Pasoleati said:
A fighter for rough conditions for low and medium altutudes
Specs:
-R-1820 H-series with water injection (1475 hp)
-wing area perhaps around 19-20 sq.m.
-Fowler flaps with a maneouver setting actuaed by a stick switch
-fuel load some 600 litres
-armament 2 x 20 mm cannon
-undercarriage suitable for fields

I began thinking this idea after pondering two issues:
1. The Finnish Myrsky development was hampered by the indecision between speed and turn and in VL's designers' limited minds it was basically a question of wing area, no consideration being given to e.g. efficient manoeuvre flaps.
2. In Finnish service the availability rates of aircraft was much higher with air-cooled radials vs. liquid-cooled ones.
3. Ruggedness of general construction is of great importance. Especially that of the undercarriage.
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If I'm reading this right, we don't have a say about engine choice, application of post-war engines in ww2 time-frame, expected performance once airborne, actual country of manufacture? Or we do?
 
  • SFA DB-605B (1475 hp)
  • wing area 22 sq.m. ish
  • Fairey-Youngman flaps (cuz muh stability)
  • fuel load: 2x 200 liter fuel tank (one per wing), one 100 liter reserve behind cockpit as extra protection
  • armament: 1x engine mounted 30 mm MK 103 or equivelant (23 mm VYa-23) to deal with ground targets and large aircraft, 4x 8 mm machine guns, two above the cowling and one per wing
  • 3 hardpoints, one central point for a 250 kg bomb or drop tank etc, two wing points for a 50 kg bomb or drop tank
  • ability to fit retractable skiis
  • storage room behind reserve fuel tank for cargo, smoke generator or target tug equipment
 
blockhaj said:
  • SFA DB-605B (1475 hp)
  • wing area 22 sq.m. ish
  • Fairey-Youngman flaps (cuz muh stability)
  • fuel load: 2x 200 liter fuel tank (one per wing), one 100 liter reserve behind cockpit as extra protection
  • armament: 1x engine mounted 30 mm MK 103 or equivelant (23 mm VYa-23) to deal with ground targets and large aircraft, 4x 8 mm machine guns, two above the cowling and one per wing
  • 3 hardpoints, one central point for a 250 kg bomb or drop tank etc, two wing points for a 50 kg bomb or drop tank
  • ability to fit retractable skiis
  • storage room behind reserve fuel tank for cargo, smoke generator or target tug equipment
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Skip those entirely, rifle caliber MGs are marginally effective against all-metal construction aircraft. Swap for at least 13-15mm caliber MGs or 20mm cannon.
 
Scott Kenny said:
Skip those entirely, rifle caliber MGs are marginally effective against all-metal construction aircraft. Swap for at least 13-15mm caliber MGs or 20mm cannon.
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they add versatility for their weight, ideal for strafing troops and dealing with other smaller fighters
 
Scott Kenny said:
Not really. Not if those lighter fighters are metal skinned. Swap 4x rifle-caliber MGs for 2x 13-15mm MGs.
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Rifle caliber projectiles can easily penetrate aircraft plate when fitted with a steel core, heavier armament is really just for dealing with armour protection and very sturdy aircraft. For such, there is the engine cannon. Heavier machine guns and cannons, however, are often less effektive when dealing with troops, due to their traditional lower rate of fire and often more limited ammunition load.
 
blockhaj said:
Rifle caliber projectiles can easily penetrate aircraft plate when fitted with a steel core, heavier armament is really just for dealing with armour protection and very sturdy aircraft. For such, there is the engine cannon. Heavier machine guns and cannons, however, are often less effektive when dealing with troops, due to their traditional lower rate of fire and often more limited ammunition load.
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Everyone and his brother replaced RCMGs on their aircraft whenever there was option to upgrade. RCMGs were failing when they were confronted with back armor + aircraft skinning, as well as against the bullet-proof glass. OTOH, the HMGs were dealing a lot of damage even against the sturdy aircraft with protection, talk the 4-gun battery from the P-51B (let alone the 6 gun battery from the P-51D) against the Fw 190s and Bf 110s.
HMGs will have a field day against the infantry behind the brick walls, sandbags, trees/branches, or in lightly armored vehicles like the halftracks that were widely used. Cannons don't require direct hit to make a kill against the troops.

In a more affirmative tone, something for 1939, provided we can get most of the bells and whistles available in that time or earlier, my ideal fighter would've looked like the D.520, He 100 (but with normal cooling), VG-33 or the MC.202. I'd avoid radials of the time, since the extra performance will keep my pilots alive for longer - those take a lot of time and effort to 'produce'. I'd also avoid Bf 109 or Spitfire due to their narrow track undercarriages (thus might be trickier to use on the rugged terrains, at least in theory), and the Hurricane or MS.406 since these were badly behind the curve.
If the mud is problem, remove the main wheel covers.
Fowler flaps are good idea.
Guns - two 20mm Shvaks, or 4 HMGs (Breda 12.7mm is debugged and powerful enough).
 
tomo pauk said:
Everyone and his brother replaced RCMGs on their aircraft whenever there was option to upgrade. RCMGs were failing when they were confronted with back armor + aircraft skinning, as well as against the bullet-proof glass. OTOH, the HMGs were dealing a lot of damage even against the sturdy aircraft with protection, talk the 4-gun battery from the P-51B (let alone the 6 gun battery from the P-51D) against the Fw 190s and Bf 110s.
HMGs will have a field day against the infantry behind the brick walls, sandbags, trees/branches, or in lightly armored vehicles like the halftracks that were widely used. Cannons don't require direct hit to make a kill against the troops.

In a more affirmative tone, something for 1939, provided we can get most of the bells and whistles available in that time or earlier, my ideal fighter would've looked like the D.520, He 100 (but with normal cooling), VG-33 or the MC.202. I'd avoid radials of the time, since the extra performance will keep my pilots alive for longer - those take a lot of time and effort to 'produce'. I'd also avoid Bf 109 or Spitfire due to their narrow track undercarriages (thus might be trickier to use on the rugged terrains, at least in theory), and the Hurricane or MS.406 since these were badly behind the curve.
If the mud is problem, remove the main wheel covers.
Fowler flaps are good idea.
Guns - two 20mm Shvaks, or 4 HMGs (Breda 12.7mm is debugged and powerful enough).
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ShVAKs are cheating. Those are some of the most overpowered weapons of WW2.
 
RCMGs worked fine against 1930s vintage, fabric-covered biplanes, but were not as effective against stressed-skin 1940s airplanes.
Which is why most WW2 combatants converted to 20mm or larger auto-cannons as soon as they could.
Only the USA stuck with .50 calibre HMGs, but that was more a matter of poor quality-control in the American factories that tried to make 20mm cannons.
Can we agree that this fictional fighter needs 1 to 3 auto-cannons in the 20 to 35mm range?

Over on the fictional RCAF ‘46 thread, I speculated about a fictitious variant on the Grumman Wildcat/Martlet powered by a Wright R-1820, single-row, radial engine with a single 20mm Polsten auto-cannon firing through the raised prop hub.
R-1820 had excellent growth potential with the first variant only producing 700 horsepower, but post-war (e.g. Grumman Tracker) variants producing 1500 hp. A tightly-cowled radial engine could be almost as low drag as an inline engine by the time you add a spinner and maybe a cooling fan ala. FW.190. See the much-modified, post-war, Grumman F8F Bearcat racer for details.
 
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Scott Kenny said:
ShVAKs are cheating. Those are some of the most overpowered weapons of WW2.
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Good points were that it was available early enough, it was suitable for synchtonizstion, rate of fire was good, it was belt fed from day one.
Weak point was the very light shell, that carried perhaps half of chemical contents of what 20mm Hispano or Oerlikon had, and even less than what the 20mm 'Mine' shell had.
 
riggerrob said:
R-1820 had excellent growth potential with the first variant only producing 700 horsepower, but post-war (e.g. Grumman Tracker) variants producing 1500 hp. A tightly-cowled radial engine could be almost as low drag as an inline engine by the time you add a spinner and maybe a cooling fan ala. FW.190. See the much-modified, post-war, Grumman F8F Bearcat racer for details.
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The later 1820s have had precoius few parts commonality with the pre-war versions.
If a fighter powered with the 12 cyl engine has just barely lower drag, that means that the designer of that fighter botched the job in the 1st place.
The Fw 190A (radial engine with an exemplary installation) was 10% draggier than the 190D9 (V12 engine with okay-ish installation); the P-51 was even less draggier than 190D.
 
tomo pauk said:
Good points were that it was available early enough, it was suitable for synchtonizstion, rate of fire was good, it was belt fed from day one.
Weak point was the very light shell, that carried perhaps half of chemical contents of what 20mm Hispano or Oerlikon had, and even less than what the 20mm 'Mine' shell had.
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Rate of fire was beyond "good"... ~800rpm is outstanding for a 20mm cannon!
 
One trigger for this project is the FM-2. It has some annoying features. The engine installation is a far cry from an ideal one. To me s proper radial installation must have all the following:
-cooling fan (according to an article by a Wright engineer in SAE Journal a cooling can be used to improve even performance)
-spinner
-sliding cooling gills (outwards opening cowl flaps are extremely draggy; minimum drag vs. maximum cooling easily with a 10 % speed difference plus in many single-engined one affected visibility over the nose)
-cowling designed to provide easy access to engine: perhaps a "banana-peel type"
-internally mounted dust filter (dust kills engines)

As for armament, no chance for rifle-calibre mgs; to give decent firepower tere would have to be lots of them=heavy.

In heavy machine gun category, the best guns were the Berezin and the Finnish Lkk 42 (vastly better than the Yank M2). But, I would choose 2 x MG 151/20 E closely fitted and with 250 - 300 rpg.
 
Pasoleati said:
... the Finnish Lkk 42 (vastly better than the Yank M2)...
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I'm curious as to what way(s) the VKT 12,70 LKk/42 was superior to the AN-M2.

My understanding was that the LKk/42 was essentially a 13.2 mm FN-Browning copy (courtesy of the Swedes) - albeit bored for 12.7 x 99mm and with mounts adjusted to match the Ilmavoimat's older Browning MG 53-2s.
 
Apophenia said:
I'm curious as to what way(s) the VKT 12,70 LKk/42 was superior to the AN-M2.

My understanding was that the LKk/42 was essentially a 13.2 mm FN-Browning copy (courtesy of the Swedes) - albeit bored for 12.7 x 99mm and with mounts adjusted to match the Ilmavoimat's older Browning MG 53-2s.
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100% correct, however the FN aircraft Browning HMG was better than the AN/M2 for several reasons, the two main ones being less weight and way higher fire rate.
 
Apophenia said:
I'm curious as to what way(s) the VKT 12,70 LKk/42 was superior to the AN-M2.

My understanding was that the LKk/42 was essentially a 13.2 mm FN-Browning copy (courtesy of the Swedes) - albeit bored for 12.7 x 99mm and with mounts adjusted to match the Ilmavoimat's older Browning MG 53-2s.
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Fired much faster and the barrels weren't throwaways after longer bursts. Basically 4 x Lkk 42 equals 6 x M2 in firepower.
 
blockhaj said:
100% correct, however the FN aircraft Browning HMG was better than the AN/M2 for several reasons, the two main ones being less weight and way higher fire rate.
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Pasoleati said:
Fired much faster and the barrels weren't throwaways after longer bursts. Basically 4 x Lkk 42 equals 6 x M2 in firepower.
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I have heard these claims about the FN Browning and its Finnish variant before but I am skeptical about some of them. The rate of fire commonly given for these FN Brownings is 1,080 rounds per minute which is very impressive considering the large effort the USA made to develop the eventual AN/M3. Besides for Springfield Armory work was also done by High Standard and Frigidaire and the resulting AN/M3 with its ROF of 1,250 rounds per minute didn't enter production until 1945. Only 2,400 were made before the war ended and it necessitated many redesigned components from the AN/M2 some of which required better metallurgy to withstand the higher ROF. And all of this was done by a country producing hundreds of thousands of Browning machine guns. Surely they would have had some knowledge about or examples of the FN produced guns to see what they were doing differently to have achieved such impressive performance back in 1939.

As for the barrels I'm not sure what they could have been doing differently from the American built guns. During the war stellite lining was introduced which made a huge difference so maybe the FN guns had that from the start?
 
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Colonial-Marine said:
I have heard these claims about the FN Browning and its Finnish variant before but I am skeptical about some of them. The rate of fire commonly given for these FN Brownings is 1,080 rounds per minute which is very impressive considering the large effort the USA made to develop the eventual AN/M3. Besides for Springfield Armory work was also done by High Standard and Frigidaire and the resulting AN/M3 with its ROF of 1,250 rounds per minute didn't enter production until 1945. Only 2,400 were made before the war ended and it necessitated many redesigned components from the AN/M2 some of which used required better metallurgy to withstand the higher ROF. And all of this was done by a country producing hundreds of thousands of Browning machine guns. Surely they would have had some knowledge about or examples of the FN produced guns to see what they were doing differently to have achieved such impressive performance back in 1939.
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I mean, AN/M2 aircraft .50cals had a ROF of about 800rpm. Putting an aircraft bolt into a ground M2 gives about a 600rpm rate of fire, the aircraft bolt is physically lighter than the ground bolt. Using the shorter and thinner profile (= much lighter) aircraft barrel gets you the rest of the 800rpm.

I suspect part of the reason for the higher rate of fire in the FN Brownings was the 13.2x99mm Hotchkiss chambering. That has more powder than .50BMG, so the recoil forces are going to be higher. Higher recoil forces equals higher bolt speed equals higher rate of fire. Dunno about 25% higher, but the FN barrels would have been a bit lighter than AN barrels just due to the larger bore.

Colonial-Marine said:
As for the barrels I'm not sure what they could have been doing differently from the American built guns. During the war stellite lining was introduced which made a huge difference so maybe the FN guns had that from the start?
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That's what I suspect.
 
For a pre/early-war design, the Belgian Renard R36, R37 and R38 fighters pretty much check all boxes.
Simple and rugged construction, all-round vision cockpit (not common in 1940), wide track landing gear, a variety of engines (in-line and radial) and armaments to choose from (including the famous FN 13.2mm MG)...
 

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Colonial-Marine said:
I have heard these claims about the FN Browning and its Finnish variant before but I am skeptical about some of them. The rate of fire commonly given for these FN Brownings is 1,080 rounds per minute which is very impressive considering the large effort the USA made to develop the eventual AN/M3. Besides for Springfield Armory work was also done by High Standard and Frigidaire and the resulting AN/M3 with its ROF of 1,250 rounds per minute didn't enter production until 1945. Only 2,400 were made before the war ended and it necessitated many redesigned components from the AN/M2 some of which used required better metallurgy to withstand the higher ROF. And all of this was done by a country producing hundreds of thousands of Browning machine guns. Surely they would have had some knowledge about or examples of the FN produced guns to see what they were doing differently to have achieved such impressive performance back in 1939.

As for the barrels I'm not sure what they could have been doing differently from the American built guns. During the war stellite lining was introduced which made a huge difference so maybe the FN guns had that from the start?
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1703746345974.png
900-1100 vs 600-800 rpm
 
blockhaj said:
View attachment 715072
900-1100 vs 600-800 rpm
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Well I guess the question remains how did they manage to achieve that? Developing the AN/M3 proved quite a challenge even with the scale of manufacturing the USA had to work with. And why didn't Springfield Armory or the others have any examples to take apart? I would be surprised if none of the guns ever found their way to the UK at some point. A lot of other stuff from Belgium did.
 
Colonial-Marine said:
Well I guess the question remains how did they manage to achieve that? Developing the AN/M3 proved quite a challenge even with the scale of manufacturing the USA had to work with. And why didn't Springfield Armory or the others have any examples to take apart? I would be surprised if none of the guns ever found their way to the UK at some point. A lot of other stuff from Belgium did.
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Like I said, 13.2mm Hotchkiss is more powerful than .50bmg, which will drive up the cyclic rate, and the barrels are going to be lighter even if the outer profile is the same as the AN/M2 .50cal due to larger chamber and bore. Those two combined would not surprise me to get +200rpm out of the gun, and the total is only +300rpm.
 
Colonial-Marine said:
I would be surprised if none of the guns ever found their way to the UK at some point.
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I am not sure whether any did. In February 1940 Britain and France selected the 13.2mm FN-Browning as a common machine gun but by the time the administrative wheels got into motion, Belgium was already being overrun before anything could be salvaged, or indeed before a binding deal was agreed.
Britain seems to have led in the selection, they chose it pretty quickly over the AN/M2 and Breda-SAFAT. Whether was on the basis of firing trials or judging off brochure figures I don't know.
 

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