1935-1945 light fighters alternatives

[tomo pauk]

In order not to clog the current Fw light fighter thread, guess we might discuss the similar for the other countries.
Some basic rules, if you don't mind
Materials, engines, aerodynamics, fuel and weapons of the day only. So no revolver cannons, no composites, no supercritical wing profiles etc. 87 oct fuel is what can be expected, higher octane fuel might or might not came. Jet engines - if historically available to the makers. Bonus points if the engine chosen is something widely available, even if it is not the best engine. Firepower - it should be realistically able to kill an enemy fighter of the day, and harm a bomber. 'Normal' maneuverability and handling.

As noted in another thread, lightweight fighter is not the same thing for any country chosen. Europeans will be happy with a short range fighter, while Japanese and US will ask for the greater ranges. Similar with firepower, some services were content with just a pair of LMGs, while the other were asking for more. Japanese will ask for maneuverability, probably as a #1 priority.
Requirements will also change with time.

To start the ball rolling - USAAC makes the deal with NAA for the P-509 project.

 

[Topi]

My idea would be a British fighter utilising mostly non-strategic materials and second-line engines. A merger of Miles and Martin-Baker results in a light fighter designed by Martin and inspired by the Kestrel and the Master. It uses duramold or alternateively the plywood construction of the Mosquito licensed from de Havilland. Its wing utilises a laminar flow cross-section with split flaps and slots, and contains a broad track inward-retracting main landing gear and the armament, made of two .303 Brownings and two FN-Brownings chambering the 15 mm BESA round. The aircraft is engine-agnostic and can utilise a RR Peregrine, Fairey P12 Prince, a Napier Dagger or Bristol Taurus (an improved A/S Tiger with a third crankshaft bearing would also be possible) with the liquid-cooled engines in a power egg -configuration featuring a beard radiator. It features a bubble canopy with the cockpit on the CoG and the U-shaped main fuel tank underneath, forward and behind the cockpit and small auxilliary tanks in the wings. An ability to carry a 500 lb bomb or a 50 imperial gallon drop tank on the centreline.

 

[tomo pauk]

British were readily adopting the foreign stuff when they deemed opportune to do it.
One of the ways they get a light fighter in service might've been that an engine-less VG-33, with some engineers and documentation, is shipped to the UK in order to have the Peregrine or the Merlin installed for trial purposes in late 1939. So with the 1st engine, it is actually faster than a 'normal' VG-33 (Peregrine makes better power than the HS engine on the VG-33), talk ~570 km/h, and with the Merlin III it does around 600 km/h. British tuck in 6 LMGs in the wing for the trials, since the RR V12s do not allow for the motor cannon installation.
In-series examples are powered by the Merlin 45 from early 1942, capable for close to 640 km/h (a tad under 400 mph), and have two of the LMGs in the wings replaced with two .50 Browning, for total of 2 HMGs and 4 LMGs.

 

[Apophenia]

British were readily adopting the foreign stuff when they deemed opportune to do it.
One of the ways they get a light fighter in service might've been that an engine-less VG-33, with some engineers and documentation, is shipped to the UK in order to have the Peregrine or the Merlin installed for trial purposes in late 1939. So with the 1st engine, it is actually faster than a 'normal' VG-33 (Peregrine makes better power than the HS engine on the VG-33), talk ~570 km/h, and with the Merlin III it does around 600 km/h. British tuck in 6 LMGs in the wing for the trials, since the RR V12s do not allow for the motor cannon installation.
In-series examples are powered by the Merlin 45 from early 1942, capable for close to 640 km/h (a tad under 400 mph), and have two of the LMGs in the wings replaced with two .50 Browning, for total of 2 HMGs and 4 LMGs.

I did a similar Commonwealth VG-33 development story on Beyond the Sprues back in 2013. In this ATL, the Arsenal de l'Aéronautique had contracted to produce VG 33 airframes in Québec (closer to suitable wood supplies).

After France falls, V-1710-powered VG 32 analogues are built for the RCAF as the Arsenal Ares. These are followed by revised, Merlin-powered Arsenal Achilles fighters. On the offchance that anyone is interested, this 8-part series started here:

- https://beyondthesprues.com/Forum/index.php?topic=351.msg45350#msg45350

 

[tomo pauk]

For the Luftwaffe - someting based on the He 100; just because the fighter is light does not exclude it being as streamlined as possible
Start out with the Jumo 210G in the nose, one or two MG FF cannons + a few LMGs. No fancy surface cooling, use the normal engine with the 'beard' radiator. It should've been somewhat faster than the He 112B (510 km/h - so possibly 530 km/h?), while the very modest consumption combined with the good fuel load will provide it with a very useful range & endurance.
Once Czechia is annexed, there are hundreds of HS 12Y engines on the irrelevant Avia fighter biplanes (500+), plus what can be gotten in the warehouses and from the Avia factory. Re-engine it with these engines, that will offer 20% greater power than the Jumo 210G. Should be capable for anything the VG-33 was capable for. Here is the Avia He 100 concept executed in plastic, plus the side elevation by your's truly.

 

[HoHun]

Hi Tomo,

Bonus points if the engine chosen is something widely available, even if it is not the best engine. Firepower - it should be realistically able to kill an enemy fighter of the day, and harm a bomber. 'Normal' maneuverability and handling.

Except for the bonus points, isn't that (and the rest of the opening post) simply the description of a general single-engine fighter?

It might be easier to respond to the opening post if you stated certain specifications to be met.

Assuming a light fighter will sacrifice some performance compared to the non-light fighter the same manufacturer could design and built instead, there must be some major advantage for the light fighter to be built in spite of these sacrifices.

Regards,

Henning (HoHun)

 

[tomo pauk]

Except for the bonus points, isn't that (and the rest of the opening post) simply the description of a general single-engine fighter?

General single-engine fighters were, or at least that was an intention, powered by the best engines of the day available. Like DB601 and BMW 801 in Germany, turboed V-1710 and R-2800 in the USA (plus Packard Merlin), and in the UK Merlin, Sabre and Griffon. Note my stipulation about the light fighter:

Bonus points if the engine chosen is something widely available, even if it is not the best engine.

(my bold)

It might be easier to respond to the opening post if you stated certain specifications to be met.

Here we have a problem with the moving goal post due to the year chosen. But let's say that the fighter will need to offer at least 90% of speed and RoC of what the best 1-engined in-pipeline fighter offers.
(in pipeline = roughly, there is an existing prototype and preparations for the series production are underway).

So we'd want for RAF a fighter that does ~290 mph by the time Hurricane is around (1937-38), as well as a 320+ mph fighter by the time Spitfire is around (1938-39), and neither of the light fighters uses the Merlin. So come 1940, there is no need to sit any pilot in a Gladiator, Buffalo or a Mohawk, and there is a fighter that can be sent and sold abroad without hurting the RAF build-up.
By mid 1942, with advent of the Typhoon Spitfire IX, the goal post is 360 mph for the light fighter (although a Yak-3-sized fighter powered by the Merlin 45 should be much faster than that, seen how fast the Yak-3 was on, for 1944, an obsolete engine).

Assuming a light fighter will sacrifice some performance compared to the non-light fighter the same manufacturer could design and built instead, there must be some major advantage for the light fighter to be built in spite of these sacrifices.

Advantages for the British: nobody needs to sit in the aforementioned trio of the fighters, plus later (1941- late 1943) on the Hurricane. It might be faster than a Spitfire on the same engine, that is a major boon in 1941-43.
For the Germans it is similar - no need for their Allies to fight in obsolete fighters, plus it should get rid of some of the flaws of the Bf 109, like the undercarriage, or the general un-friendliness for the low-time pilots, as well as getting the better fuel mileage (interesting feature for the countries lacking avgas); Germans might've looked at the He 100 minus the fancy cooling and lower powered engines to get them started.
For the Americans, a way to extract better speed and RoC than what the P-40 was offering on the same engine, and probably the same vs. the P-39, without waiting for the NAA genius to come out with the Mustang.
For the Italians, a way to reduce the performance advantage the Allies had come 1943; getting rid of the biplanes post-haste is also a big deal. A faster way of manufacturing would've reduced their dependence on Germany.

 

[Archibald]

How about Bloch MB-700 (scaled down 83% MB-150) with Bristol Mercury or Perseus radials ?

 

[tomo pauk]

How about Bloch MB-700 (scaled down 83% MB-150) with Bristol Mercury or Perseus radials ?

I'd choose the Mercury, since it was readily available both for the British needs and export. Pour in the 100 oct fuel and it makes just a smidge under 1000 HP at ~9000 ft. Mercury is also a tad smaller, a thing beneficial to a fighter A/C.
Vs. the original MB-700, it will add a bit to the nose of the aircraft, but that is more than compensated by the greater power at any altitude.

The Canadian production of the MB-700 might've used the Twin Wasp Junior, engine often featuring as an alternative to the G&R 14M.

(either of the three engines mentioned here would've been much improved, and fast, by the installation of a then-modern supercharger...)

 

[tomo pauk]

The HS-12X engine on the MB-700-like fighter would've also been a good fit. Power of 690 HP at 3900m, vs. the G&R 14M doing 650 HP at 4000m, but, more importantly, going V12 means shedding some drag, as well as getting easier to the full benefits of the exhaust thrust.
As a reality check - the He 112B with 670 HP at 3700m was good for just above 500 km/h, while being with a somewhat bigger and draggier wing than the 700.
Potez 230 was the design similar to what I'm suggesting here, supposedly good for 560 km/h (!!). A really diminutive fighter, wing area half of what Spitfire or P-40 had.

Another similar designs were the Ambrosini designs, the 207 and 403, good (the 207) for 575 km/h on 750 HP at 4000m. These designs were also supposed to be very fast to produce, contrary to the 'normal' Italian fighters of the day that were notoriously slow in that regard.

(all power figures listed are without ram effect)

 

[Archibald]

I did a similar Commonwealth VG-33 development story on Beyond the Sprues back in 2013. In this ATL, the Arsenal de l'Aéronautique had contracted to produce VG 33 airframes in Québec (closer to suitable wood supplies).

After France falls, V-1710-powered VG 32 analogues are built for the RCAF as the Arsenal Ares. These are followed by revised, Merlin-powered Arsenal Achilles fighters. On the offchance that anyone is interested, this 8-part series started here:

- https://beyondthesprues.com/Forum/index.php?topic=351.msg45350#msg45350

We have toyed with similar ideas in France Fights On (where, on June 13, 1940 the gaullist faction that want France to keeps fighting from Algiers, carries the day over Pétain defeatists).
Production of VG-30 series in Algeria was very tempting and almost happened - but realism set on: no viable industry there, not even for wood construction. So Cash& carry it was, then Lend lease: P-40s first, then Mustang development much faster than OTL...

 

[Apophenia]

...Production of VG-30 series in Algeria was very tempting and almost happened - but realism set on: no viable industry there, not even for wood construction...

During wartime, skilled wood-workers (in this case, in la Métropole) are likely to be under-employed while, at the same time, steel and aluminium become highly-valuable strategic materials. That reasoning was behind every predominantly wooden construction aircraft during WW2.

The approach made good sense ... so long as the country building wooden airframes has sufficient access to suitable timber. In the case of the VG.33, France lacked adequate access to aircraft-quality woods - especially spruce.

The VG.33 structure drew heavily upon cèdre rouge from Morocco and Algeria. So, moving production to Algeria seemed to make sense ... except (along with skilled labour shortages) North African stocks of cedar were already strained. This necessitated the sourcing alternative wood supplies from Romania and North America.

Alternative cedars sourced particularly from North America could have been better utilised in a VG.33 airframe re-designed to make full use of larger trees. Because of the woods involved, RW VG.33 airframe construction showed little advance over techniques used in aircraft like the Lockheed Vega over a decade earlier.

Beyond easier access to North American wood stocks, a major advantage of producing VG.33 airframes in Québec would have been the opportunity to incorporate then-current US work on premoulded plywood forms for aircraft structures. Adopting premoulded skins would have simplified construction - translating into a quicker-to-make and slightly lighter structure for the Arsenal fighters.

_______________________________

[1] Those could have been Eugene Vidal's Weldwood (which caught early Canadian interest), Timm Aeromold, or Fairchild Duramold, etc.

 

[HoHun]

Hi Tomo,

But let's say that the fighter will need to offer at least 90% of speed and RoC of what the best 1-engined in-pipeline fighter offers.

As a rule of thumb, I'd say a 10% power reduction in a WW2 fighter will only allow a 5% weight and size reduction, since many items of the weight breakdown are fixed and don't scale with power - pilot, armour, armament, radio, etc.

Unless one makes sacrifices with regard to capabilities or military payload, a light fighter will always be a bad deal as long as trained pilots are a limited resource, as even if a cheap fighter can be easily replaced, an experienced pilot usually can't.

I don't think that it's a coincedence that historically, fighters were always designed for and upgraded to the most powerful engine types their airframes could take.

Regards,

Henning (HoHun)

 

[tomo pauk]

As a rule of thumb, I'd say a 10% power reduction in a WW2 fighter will only allow a 5% weight and size reduction, since many items of the weight breakdown are fixed and don't scale with power - pilot, armour, armament, radio, etc.

A 10% power reduction will make the fighter performing at ~95% the speed of the same fighter with the 100% engine power?
Engine that makes 20% less power will make the fighter do 90% of speed, while being 20% lighter.

Unless one makes sacrifices with regard to capabilities or military payload, a light fighter will always be a bad deal as long as trained pilots are a limited resource, as even if a cheap fighter can be easily replaced, an experienced pilot usually can't.

Lack of better fighters was a thing, too. Soviets were seating their fighter pilots in the I-16s, Hurricanes and even the I-15s for as far as 1942. British were fighting with Mohawks, Gladiators and Buffaloes into 1942. Italians were using biplanes and - bad - monoplane fighters in 1940-41. Polish fighters were badly behind the curve, so were the Yugoslav and Czech designs. Most of the French pre-1940 fighters were bad. Both the P-39 and P-40 were found lacking in such a measure that USAAF used Spitfires as top cover.
Making light fighters was not a panacea, but it might've solved the supply problems while also adding to the capability of the fighter force. Granted, in order for the later to happen, the airframe designers will also be obliged to their job very well, too.

I don't think that it's a coincedence that historically, fighters were always designed for and upgraded to the most powerful engine types their airframes could take.

Light fighter is not a regular fighter that got the lesser engine.

 

[HoHun]

Hi Tomo,

Engine that makes 20% less power will make the fighter do 90% of speed, while being 20% lighter.

The fighter's weight breakdown includes

- weight of engine, cooling system and fuel, which scale linearly with power,
- pilot, payload, armour and and equipment weight, which don't scale wirh power, and
- airframe, which scales with weight and wing area with exponents vaguely around 0.5 (according to Gudmundsson's textbook).

So 20% less power leads to a fighter with:

- 80% power section weight (including fuel)
- 100% pilot, payload, armour and and equipment weight
- >90% structural airframe weight, depending on the share of each of the three main weight categories in the total weight.

Inevitably, a 20% power reduction will result only in a proportionally smaller weight reduction, unless you remove either operational equipment, like part of the armour, reduce other operationally relevant parameters, such as load factor, or maybe reduce range and thus get away with carrying less fuel.

All of which would be undesirable to the fighter's buyer, who gets to decide whether he wants a light fighter for his air force.

If the industry isn't capable of producing the desired number of 100%-fighters, the buyers hand is forced, but then the decision is about whether the light fighter is better than not having a fighter at all, not about if it's a better buy than a 100%-fighter.

Regards,

Henning (HoHun)

 

[tomo pauk]

The fighter's weight breakdown includes

- weight of engine, cooling system and fuel, which scale linearly with power,
- pilot, payload, armour and and equipment weight, which don't scale wirh power, and
- airframe, which scales with weight and wing area with exponents vaguely around 0.5 (according to Gudmundsson's textbook).

It should also be noted that, since the lighter fighter can do with the smaller wing, both the weight and drag that are related to the wing are lower. Smaller wing that is otherwise same as a bigger wing will be less draggy. For example on the V12-powered Tank's aircraft, wing-related drag amounted to 35-38% of the drag of the complete aircraft, so a reduction of the wing-related drag of, say, 15% will bring down the total drag of the aircraft by about 5%. Less powerful engine will make less of the cooling drag, that was a thing that was criticized eg. on the Spitfire (not that many other ww2 aircraft were amazing in that regard, just that Spitfire is often in the focus; Hurricane was even worse).
The two things combined will allow the fighter with 80% or power and powerplant weight to come close to more than 95% of the speed of the 100% fighter.

All of which would be undesirable to the fighter's buyer, who gets to decide whether he wants a light fighter for his air force.

If the industry isn't capable of producing the desired number of 100%-fighters, the buyers hand is forced, but then the decision is about whether the light fighter is better than not having a fighter at all, not about if it's a better buy than a 100%-fighter.

(my bold)
Kicker is that the bolded part was true for many countries - see UK buying fighters that were even lower-performing than the Hurricane, or France trying - if to late - to make a fighter around the obsolete version of the HS 12Y. Many times the 100% fighters didn't panned, either, or the 100% engines didn't materialized, or there were substantial delays, sometimes threatening the whole projects. We can take a look at the Typhoon/Tornado, Fw 190, A7M, P-60, even the P-47B was a horrible mess. See how long it took for the Soviets to find a replacement to the I-16, putting them behind the West by 1939-40. Italians making the biplane fighters, of all things.

 

[tomo pauk]

Inevitably, a 20% power reduction will result only in a proportionally smaller weight reduction, unless you remove either operational equipment, like part of the armour, reduce other operationally relevant parameters, such as load factor, or maybe reduce range and thus get away with carrying less fuel.

To touch a bit on this.

A good part of the fighter's weight was devoted to the firepower it carried. While most of the airforces were favoring the ever-increased firepower and were prepared to pay the price in weight and in whatnot, they were still buying the fighters with reduced firepower. Talk the full-size 4-gun fighters of the US (P-51A, B and C, FM2, and the F8F following) despite even the earlier fighters having 6-8 HMGs, Ki-43 with half the firepower of these US fighters, Bf 109 often being uder-armed compared with the Fw 190 (granted, this one often looked over-armed, to it's detriment). A greater firepower was not a guarantee that one will fare better, so we have the instances of the 6-gun P-40s suffering against the Axis best, or the Hurricane IIC being an under-performer (had a lot to do with things other than the weapon set-up), or the Ki-43s often besting the Allied fighters, even giving the Spitfire VIII a tough time. Fw 190 vs. P-51B was another example of the firepower taking the back seat to the performance.

That was a long-winded way to say that a light fighter armed with perhaps two HMGs by the mid-1930s, and with two smaller 20mm cannons (talk Oerlikon L, FF, or an over-grown HMG ) by the early 1940s will pack a punch that can badly harm the bombers and can kill the fighters, without going over-board with the weight and volume devoted to the weapon suite.

 

[HoHun]

Hi Tomo,

That was a long-winded way to say that a light fighter armed with perhaps two HMGs by the mid-1930s, and with two smaller 20mm cannons (talk Oerlikon L, FF, or an over-grown HMG ) by the early 1940s will pack a punch that can badly harm the bombers and can kill the fighters, without going over-board with the weight and volume devoted to the weapon suite.

Well, HMGs are actually heavy in comparison to their firepower if you consider the weight of the ammunition too. Not that a battery of 2 HMGs and 2 cannon wasn't more or less average non-light fighter armament even in 1945 ...

But that's a secondary consideration ... the main thing is that when you're comparing clean-sheet designs, the higher-powered "non-light" fighter will have serious advantages over the light fighter due to having a better power-to-weight ratio.

As the cost of a fighter force not only depends on the purchased aircraft, but also on the trained fighter pilots flying these aircraft, it might actually be more expensive overall to operate lower-performing cheap fighters, especially if you consider that experienced pilots might well be a limited resource, and their chances of survival and continued service are higher when flying the expensive non-light fighters.

Regards,

Henning (HoHun)

 

[Foo Fighter]

In order not to clog the current Fw light fighter thread, guess we might discuss the similar for the other countries.
Some basic rules, if you don't mind
Materials, engines, aerodynamics, fuel and weapons of the day only. So no revolver cannons, no composites, no supercritical wing profiles etc. 87 oct fuel is what can be expected, higher octane fuel might or might not came. Jet engines - if historically available to the makers. Bonus points if the engine chosen is something widely available, even if it is not the best engine. Firepower - it should be realistically able to kill an enemy fighter of the day, and harm a bomber. 'Normal' maneuverability and handling.

As noted in another thread, lightweight fighter is not the same thing for any country chosen. Europeans will be happy with a short range fighter, while Japanese and US will ask for the greater ranges. Similar with firepower, some services were content with just a pair of LMGs, while the other were asking for more. Japanese will ask for maneuverability, probably as a #1 priority.
Requirements will also change with time.

To start the ball rolling - USAAC makes the deal with NAA for the P-509 project.

https://www.secretprojects.co.uk/threads/aerolite-spitfire.40545/#post-564992
More than one type of composite available. Might have been quite useful.

 

[tomo pauk]

Well, HMGs are actually heavy in comparison to their firepower if you consider the weight of the ammunition too. Not that a battery of 2 HMGs and 2 cannon wasn't more or less average non-light fighter armament even in 1945 ...

My mistake - I should've stipulated in the more clear terms that is not 2 HMGs + 2 cannons for the 1940s, but rather that a pair of cannons replaces the pair of HMGs.

But that's a secondary consideration ... the main thing is that when you're comparing clean-sheet designs, the higher-powered "non-light" fighter will have serious advantages over the light fighter due to having a better power-to-weight ratio.

In an ideal world - that is certainly the truth.
In the real world - the 'non-light' fighters many times went stillborn or were running late, either due to the airframe design team botching the things, or the engine deign team not being as good as it is supposed to be, or because of the air ministries making bad decisions, or because the situation in the country and in it's surrounding went from bad to worse. Many times the 'non-light' fighters were hard to manufacture in the pace required by the customer and the current situation a country might find itself in.

 

[HoHun]

Hi Tomo,

In the real world - the 'non-light' fighters many times went stillborn or were running late, either due to the airframe design team botching the things, or the engine deign team not being as good as it is supposed to be, or because of the air ministries making bad decisions, or because the situation in the country and in it's surrounding went from bad to worse. Many times the 'non-light' fighters were hard to manufacture in the pace required by the customer and the current situation a country might find itself in.

Weren't the light fighters invariably those of an older generation? I can't spontaneously
think of any light fighter designed as such seeing widespread service in WW2. You mentioned the Yak-3, but I belive it really a lightened version of an obsolescent 100%-fighter with the same engine, not a purpose-built 80% power aircraft.

Regards,

Henning (HoHun)

 

[tomo pauk]

Weren't the light fighters invariably those of an older generation? I can't spontaneously
think of any light fighter designed as such seeing widespread service in WW2. You mentioned the Yak-3, but I belive it really a lightened version of an obsolescent 100%-fighter with the same engine, not a purpose-built 80% power aircraft.

What was a light fighter in 1943-44 was not the same as in 1936-37.
Earlier fighter made around a 600-800 HP engine (depending on a country) will be long gone by 1943-44, replaced with a 1000-1200 HP design while the 'normal' fighters are getting 1700-2500 HP engines. If the early light fighter is that good a design, it might've received the engine upgrade in the meantime.

Yak-3 was with the smaller and thinner wing than what the other Yaks had, fuel tankage was also smaller. Weight reduction was about 100-200 kg vs. the Yak-1 (despite the two HMGs on the -3 vs. two LMGs on the -1), or 200-600 kg vs. the Yak-9 (that didn't gotten the 2nd HMG until the U version).
IMO, the Yak-3 was a successful attempt to make a performer around a really obsolete (even for the Soviet conditions) engine. Can it be called a light fighter? I'd say 'yes', weighting around 2700 kg full, clean, while other people were making 5-6 ton 1-engined fighters in the same time.

 

[HoHun]

Hi Tomo,

IMO, the Yak-3 was a successful attempt to make a performer around a really obsolete (even for the Soviet conditions) engine. Can it be called a light fighter? I'd say 'yes', weighting around 2700 kg full, clean, while other people were making 5-6 ton 1-engined fighters in the same time.

So about the only successful light fighter built in WW2 was a modified 100%-fighter sacrificing medium and high altitude capability for competetiveness at low altitudes.

Unless of course we'd like to count other obsolescent fighters as light fighters too ... difficult to identify a pattern in the data set.

Regards,

Henning (HoHun)

 

[tomo pauk]

So about the only successful light fighter built in WW2 was a modified 100%-fighter sacrificing medium and high altitude capability for competetiveness at low altitudes.

The medium altitude capacities were not sacrificed, these were as good as the better Fw 190As had there, the La-7 being the only better Soviet fighter there. Yak-3 was also better than the other Yak fighters of the time, at all altitudes.
The high altitude perfomance being as it was - it was a function of the engine, that was worse in most of the regards than the Merlin III or the V-1710-39 (assumes all 3 engines use the same octane fuel), and barely better than the DB 601Aa.

M/VK-105 engines were lemons, Yakovlev design team made as good the lemonade as possible.

 

[tomo pauk]

Unless of course we'd like to count other obsolescent fighters as light fighters too ... difficult to identify a pattern in the data set.

Fw 190A and Bf 109G6 were, by 1944, obsolescent fighters.

 

[HoHun]

Hi Tomo,

Fw 190A and Bf 109G6 were, by 1944, obsolescent fighters.

Well, these are specific versions or in the case of the Me 109, even a specific sub-version of the type. I'd argue that the Fw 190A was not an obsolent airframe, as the Fw 190A-10, held up by the delays in getting the BMW 801E/F generation of engines into production (due to a lack of machine tools), would have been quite competitive. The Me 109G airframe in 1944 actually got improved engine variants, including the AS supercharger and methanol-water injection that kept it reasonably competitive too.

But my point was not obsolescence in general (the Luftwaffe sure would have loved to introduce a more modern type than the Me 109), but that there was no purpose built light fighter in WW2 that wasn't an adaptation of an obsolescent airframe with an obsolescent engine.

Of course, if we allow jet fighters, there was the Heinkel He 162 - that was a true light-weight fighter from the outset. I'd say it was a bad buy for the Luftwaffe, they really should have stuck to their 100%-fighter in the shape of the Me 262, for similar reasons that made propeller-driven light-weight fighters unattractive in general.

Regards,

Henning (HoHun)

 

[tomo pauk]

Well, these are specific versions or in the case of the Me 109, even a specific sub-version of the type. I'd argue that the Fw 190A was not an obsolent airframe, as the Fw 190A-10, held up by the delays in getting the BMW 801E/F generation of engines into production (due to a lack of machine tools), would have been quite competitive. The Me 109G airframe in 1944 actually got improved engine variants, including the AS supercharger and methanol-water injection that kept it reasonably competitive too.

The competitive engine on the Yak-3 - or the actual lack of thereof in 1944 - was also a thing, since with the VK-107 it was supposed to do 720 km/h, and even more with the -108. The two engines being roughly the equivalent of the DB 605A and AM, respectively.
(FWIW, the Shavrov's tables translated to Spanish here; Yak fighters here)

Of course, if we allow jet fighters, there was the Heinkel He 162 - that was a true light-weight fighter from the outset. I'd say it was a bad buy for the Luftwaffe, they really should have stuck to their 100%-fighter in the shape of the Me 262, for similar reasons that made propeller-driven light-weight fighters unattractive in general.

Jet fighters are a fair game.

IMO, the alternative He 162 should've been made with using the wing panels from the existing aircraft, and a bit bigger. My vote is the wing from the Me 163.
Germany was not in the position to make enough of engines for the wholesale replacement of 1-engined fighters with the 2-engined jet fighter (perhaps they would've been by some time in 1945 provided there is no Allied bomber offensive?). There is also a question of fuel - Me 262 used 3 times the fuel a Fw 190 with drop tank used for the same range and less endurance. While that fuel was not a high-octane type, someone still needs to produce it, again the German sore point.

So I'd say that a jet-powered light fighter in production by late 1943 would've been a thing for the LW, allowing them for fast replacement of the Bf 109s, while not using obscene amounts of fuel and out-performing the best Allied fighters.
Jet fighter by default is with a tricycle U/C, and there is no torque reaction - two things that the low-time pilots will appreciate dearly. Single lever engine operation without the complication, no propeller - lends itself for the rapid production.
If the MK 108 are found to be too rough on the airframe, make the lighter shell for them and install muzzle brake; a single MK 103 is also a tempting option, with two MG 131s for the piece of mind.

 

[HoHun]

Hi Tomo,

The competitive engine on the Yak-3 - or the actual lack of thereof in 1944 - was also a thing, since with the VK-107 it was supposed to do 720 km/h, and even more with the -108. The two engines being roughly the equivalent of the DB 605A and AM, respectively.

Well, I don't intend to be dogmatic about what is obsolescent or obsolete ... there are always intermediate cases, and it doesn't really affect the case of the light fighter very much.

IMO, the alternative He 162 should've been made with using the wing panels from the existing aircraft, and a bit bigger. My vote is the wing from the Me 163.

Germany was not in the position to make enough of engines for the wholesale replacement of 1-engined fighters with the 2-engined jet fighter (perhaps they would've been by some time in 1945 provided there is no Allied bomber offensive?). There is also a question of fuel - Me 262 used 3 times the fuel a Fw 190 with drop tank used for the same range and less endurance.

The question really is, what could the Me 262 achieve with the same amount of fuel as used by the Fw 190 - or the He 162, for that matter?

The Heinkel Volksjäger really shows the problems of the light fighter: It has a much reduced operational capability, it requires a higher number of pilots to make good on its promise to allow the creation of a larger fighter force, it draws production assets away from the fully competitive (or in this case, actually superior) 100%-fighters, and due to its fuel capacity being reduced in comparison to the Me 262, it actually had less combat persistence and thus had to use up a higher proportion of its fuel just travelling between bases and combat zone.

Not that it was a bad design from an aircraft design point of view, but I'd say it was designed to ill-advised specifications.

In response to the Volksjäger idea, Focke-Wulf in fact suggested a 100%-fighter in the sense of this thread, first to be powered with a single existing low-power engine, to create a light fighter substitute that was a bit poorer as a light fighter, but could be upgraded to a full-size fighter as soon as a high-powered jet engine could be provided.

So I'd say that a jet-powered light fighter in production by late 1943 would've been a thing for the LW, allowing them for fast replacement of the Bf 109s, while not using obscene amounts of fuel and out-performing the best Allied fighters.

I am not sure that this was possible with the rate of Jumo 004 development, though it seems that some time might have been saved by allocating the available strategic alloys to jet engine production. It seems that Germany over-economized strategic resources to a degree, but I'm not sure that there was much potential for having a production jet fighter in late 1943 even when applying optimistic assumptions.

If the MK 108 are found to be too rough on the airframe, make the lighter shell for them and install muzzle brake; a single MK 103 is also a tempting option, with two MG 131s for the piece of mind.

The MK 108 as an advanced-primer ignition gun is actually quite soft-shooting, if I remember the problem description correctly it was just that the aircraft skin around the muzzle could be damaged by the muzzle blast. I believe this was corrected by using thicker skin around the muzzle - the absence of MK-108-armed examples was actually caused by the re-location of the gun's manufacturing plant in order to get it out of the path of the advancing Soviet army.

Regards,

Henning (HoHun)

 

[tomo pauk]

The question really is, what could the Me 262 achieve with the same amount of fuel as used by the Fw 190 - or the He 162, for that matter?

It is a question, not the question
Me 262 cannot achieve anything with the same amount of fuel used by Fw 190, since it would've have the endurance of perhaps 20 minutes, thus being even more susceptible to the Allied LR fighters catching them during the take off and landing, as well as when they are in the process of preparation to the mission.
The other math - lets have 1/3rd of number of Me 262s instead of 100% of Fw 190s is also flaved - Germans need both quality (= performance + firepower + maneuverability + survivability + endurance, basically) and numbers. Me 262 ticks the 'quality' box, but it does not tick the 'quantity' box, because of Germans not making enough of jet engines for their needs, and because they don't have fuel for a numerous, 100% Me 262 force.

I agree that the Volksjaeger spec was faulty. Main shortcoming was that it was too late, IMO.

I am not sure that this was possible with the rate of Jumo 004 development, though it seems that some time might have been saved by allocating the available strategic alloys to jet engine production. It seems that Germany over-economized strategic resources to a degree, but I'm not sure that there was much potential for having a production jet fighter in late 1943 even when applying optimistic assumptions.

Agree that Germany over-economized strategic resources. Engine companies should've gotten the 1st call on nickel, while they (and everyone else) is still encouraged to make savings of the rare materials where possible and feasible.

The MK 108 as an advanced-primer ignition gun is actually quite soft-shooting, if I remember the problem description correctly it was just that the aircraft skin around the muzzle could be damaged by the muzzle blast. I believe this was corrected by using thicker skin around the muzzle - the absence of MK-108-armed examples was actually caused by the re-location of the gun's manufacturing plant in order to get it out of the path of the advancing Soviet army.

That is very interesting. Where these factories were located?

 

[tomo pauk]

Some suggestions on the actual light fighters; I'll use only the engines available to a country, to keep this making. Note that a light fighter is not a same thing for all the people - a full-blown fighter of France or Soviet union will be considered a light fighter by the Americans. Similar with the engines' power - 1000 HP at 5 km in 1941 will be considered a joke by the Americans or the British, while it would've been more than good in Japan or Italy.
Time/year also influences what might've been considered as a light fighter.

For Italy: They have had the interesting Ambrosini designs. Powered by the 750 HP engines, the 207 prototype was doing 575 km/h per this document (I don't belive the ~650 km/h figures a single iota). It was also supposed to be fast to produce. Considering that Italians were of opinion that two HMGs are a good firepower, these kinds of fighters would've been a boon for them if made early enough, talk service use no later than late 1940/early 41.

For Germany: Something emanating from the He 100, minus the fancy cooling. Start with the Jumo 210G in the nose, two MG FFs in the wings. Soon it can be using the captured HS 12 engines, by mid-war the DB 601s, and then the 605A.

Americans: the P-509A by NAA would've fit the bill. Ditto for their take on the FFVS J.22 idea.

Japan: again, the J.22 is a good role model for them.

UK - start out with the later Kestrel engine in the nose (745 HP at 14500 ft), on a fighter roughly size & shape of Bf 109. Peregrine is a good upgrade by 1939/40. By the time 2-stage Merlins, Sabre and Griffon are on the '100% fighters', it should've been just great with Merlin 50.

 

[HoHun]

Hi Tomo,

It is a question, not the question

Hehe, not the only question of course, but if one is considering the efficiency of the fuel usage, it's a pretty important one.

The other math - lets have 1/3rd of number of Me 262s instead of 100% of Fw 190s is also flaved - Germans need both quality (= performance + firepower + maneuverability + survivability + endurance, basically) and numbers. Me 262 ticks the 'quality' box, but it does not tick the 'quantity' box, because of Germans not making enough of jet engines for their needs, and because they don't have fuel for a numerous, 100% Me 262 force.

To measure efficiency, you always have to relate the cost to the result, which in the case of a Luftwaffe fighter for late 1944 can be simplified to "number of USAAF bombers shot down". While it's difficult to find reliable numbers, I am quite convinced that a good case can be made for the Me 262 being much more effective per sortie than a Fw 190. That means the fuel expended per bomber kill is lower for the Me 262 even though the total fuel consumption per sortie is higher.

In a similar vein, number of USAAF bombers shot down per Luftwaffe fighter pilot lost will have been lower too, and as it took a lot of fuel to fully train a fighter pilot, that was in favour of the Me 262 fleet's overall fuel efficiency as well.

That is very interesting. Where these factories were located?

As far as I know, there was just one factory, in Posen/Poznan.

Regards,

Henning (HoHun)

 

[tomo pauk]

To measure efficiency, you always have to relate the cost to the result, which in the case of a Luftwaffe fighter for late 1944 can be simplified to "number of USAAF bombers shot down". While it's difficult to find reliable numbers, I am quite convinced that a good case can be made for the Me 262 being much more effective per sortie than a Fw 190. That means the fuel expended per bomber kill is lower for the Me 262 even though the total fuel consumption per sortie is higher.

In a similar vein, number of USAAF bombers shot down per Luftwaffe fighter pilot lost will have been lower too, and as it took a lot of fuel to fully train a fighter pilot, that was in favour of the Me 262 fleet's overall fuel efficiency as well.

A small force of the Me 262s vs. what LW had in 1944 simplifies the problem for the US LR fighters - they need even more to focus on aggressive patrols close to the airfields, since the jets will still need to go there and be located there.

As far as I know, there was just one factory, in Posen/Poznan.

Thank you.

 

[HoHun]

Hi Tomo,

A small force of the Me 262s vs. what LW had in 1944 simplifies the problem for the US LR fighters - they need even more to focus on aggressive patrols close to the airfields, since the jets will still need to go there and be located there.

With a larger jet fighter fleet, the Luftwaffe would be able to commit part of the force to airfield protection, so the offensive patrols would be a bit harder than they historically were - and they were pretty tough already. Depending on the point in time when the jet fighters become available, it's also not a given that the USAAF would even be able to achieve the degree of air superiority they historically enjoyed over the Luftwaffe, which then again makes the Luftwaffe's piston fighter force more viable.

But that's a jet fighter vs. piston fighter discussion, not so much a light fighter vs. 100% fighter discussion.

Regards,

Henning (HoHun)

 

[tomo pauk]

With a larger jet fighter fleet, the Luftwaffe would be able to commit part of the force to airfield protection, so the offensive patrols would be a bit harder than they historically were - and they were pretty tough already. Depending on the point in time when the jet fighters become available, it's also not a given that the USAAF would even be able to achieve the degree of air superiority they historically enjoyed over the Luftwaffe, which then again makes the Luftwaffe's piston fighter force more viable.

Trick is that a much bigger fleet, than it was historically available, was not possible with the Me 262. Sorta like there was no realistic possibility that a large fleet of Whirlwinds is made instead of the similarly large fleet of the Spitfires and/or Hurricanes, even if Whirlwind and Peregrine start out by early 1939.

But that's a jet fighter vs. piston fighter discussion, not so much a light fighter vs. 100% fighter discussion.

It is also a discussion about a heavy fighter (Me 262) vs. a light fighter (1-engined jet fighter).

 

[HoHun]

Hi Tomo,

Trick is that a much bigger fleet, than it was historically available, was not possible with the Me 262.

You're most likely right, but I thought you had suggested that much bigger fleet as an hypothetical example for the sake of discussion

It is also a discussion about a heavy fighter (Me 262) vs. a light fighter (1-engined jet fighter).

My comment addressed the "offensive patrol" aspect of Luftwaffe jet fighter employment. I'd expect the Allies to try and suppress the jet fighter bases regardless of whether the jets stationed there are "100%" Messerschmitts or light Heinkels ... or what's your take on this?

Regards,

Henning (HoHun)

 

[tomo pauk]

You're most likely right, but I thought you had suggested that much bigger fleet as an hypothetical example for the sake of discussion
...
My comment addressed the "offensive patrol" aspect of Luftwaffe jet fighter employment. I'd expect the Allies to try and suppress the jet fighter bases regardless of whether the jets stationed there are "100%" Messerschmitts or light Heinkels ... or what's your take on this?

Regards,

Henning (HoHun)

Much bigger fleet of jet fighters is both hypothetical and for the cake of discussion - this is a what if, and on a forum
A 100% fleet of 262s might've been a fleet of perhaps 500 fighters - just to pick a number - in Spring of 1944, with another 500 fighters being a mix between 109s and 190s. A 100% fleet of light jet-powered fighters might've been a fleet of maybe 900-1000 of these fighters, and no pilot has to sit in a 109 or a 190. Trying to suppress such a large fleet of the fighters that are all better performing than the Allied best would've been a tough proposal - a 109 being in the rear view mirror and gaining on the P-51B will not work if the Allied pilot is worth his salt, while a jet fighter asked to do the same is very much doable.

 

[HoHun]

Hi Tomo,

A 100% fleet of 262s might've been a fleet of perhaps 500 fighters - just to pick a number - in Spring of 1944, with another 500 fighters being a mix between 109s and 190s. A 100% fleet of light jet-powered fighters might've been a fleet of maybe 900-1000 of these fighters, and no pilot has to sit in a 109 or a 190. Trying to suppress such a large fleet of the fighters that are all better performing than the Allied best would've been a tough proposal

I'd say that this is a case for an Operational Research approach. The He 162 has a useful fuel capacity of 575 kg, the Me 262 has about 2570 L, which at a typical jet fuel density of 0.8 kg/m^3 equates about 1000 kg per engine (for ease of comparison with the He 162).

For a very generic consumption breakdown based on the data from the contemporary Me 262 range computer (circular slide rule):

- 10 min reserve at speed for greatest endurance at sea level ... 90 kg per engine.
- 10 min climb at full power ... 206 kg per engine
- 10 min combat at 6000 m ... 173 kg per engine
- 10 min cruise out, 10 min cruise back at 6000 m, both at speed for greatest range ... 168 kg per engine

Total sum: 637 kg per engine.

So that very generic schedule, which with a cruise speed of about 700 km/h (true airspeed) allows operation in a radius of maybe 150 km of the base, is already a stretch for the (semi-hypothetical Jumo-004-engined) He 162 , which doesn't have any reserves for a diversion to an airbase in a safe distance of the possibly suppressed base it's scheduled to land on.

The Me 262 on the other hand has enough fuel for 20 min at full power, which enables it to fight for air superiority over its own base even when returning from a mission, or make a significant diversion to an airbase in a different part of Germany, when the Allied suppression effort covers not only the home base but also adjacent ones.

Of course, with a higher number of He 162 fighters, you could employ a proportion of this larger force to try and maintain air superiority over the bases, without sending these fighters off to fight against bombers.

Which course of action will offer greater chances of success? Hard to tell, but I think operating a smaller number of Me 262 fighter is the more robust option, especially in the light of the historical Luftwaffe's demands for ever-increasing operational ranges (as Willy Messerschmitt notes in his discussion of the He 162 project).

Regards,

Henning (HoHun)

 

[tomo pauk]

I'd say that this is a case for an Operational Research approach. The He 162 has a useful fuel capacity of 575 kg, the Me 262 has about 2570 L, which at a typical jet fuel density of 0.8 kg/m^3 equates about 1000 kg per engine (for ease of comparison with the He 162).
...

Thank you for the math.
As you can note, I'm not advocating the He 162 as such, but a '1-engined jet fighter' - these two are not synonyms.

(as Willy Messerschmitt notes in his discussion of the He 162 project).

Willy has a horse in that race.

 

[Archibald]

The real missed opportunity was the He-280, but that's another story.

 

[HoHun]

Hi Tomo,

Willy has a horse in that race.

Doesn't mean he was wrong!

But I mentioned this because he was merely reminding the customers what they had been asking for ... no reason to assume any bias there, they would have known their demands as well as he did.

Regards,

Henning (HoHun)