Lightweight fighter: how would've you done it?

[tomo pauk]

Let's say the air force wants a lightweight fighter, with 1st examples in service in 1940. The design is limited to a powerplant of weight under 1700 lbs complete (engine + prop + lubricating + cooling), under 900HP, to carry 200 - 300 lbs of armament, 200 - 300 lbs of ammo, fuel quantity between 80-100 US gals (or whatever it's SI or Imp equivalent, for all the measuring units) in protected tanks, at least some protection for pilot. Use just the bits pieces from one country per one design.
edit: the empty weight is to be under 4000 lbs.
What would be you proposal?

 

[FLYBOYJ]

This was "an attempt."

Bell XP-77 - Wikipedia, the free encyclopedia

 

[Shortround6]

Let's say the air force wants a lightweight fighter, with 1st examples in service in 1940. The design is limited to a powerplant of weight under 1700 lbs complete (engine + prop + lubricating + cooling), under 900HP, to carry 200 - 300 lbs of armament, 200 - 300 lbs of ammo, fuel quantity between 80-100 US gals (or whatever it's SI or Imp equivalent, for all the measuring units) in protected tanks, at least some protection for pilot. Use just the bits pieces from one country per one design.
What would be you proposal?

Take the guy who came up with the proposal and fly him 50 miles out to sea and push him out the door to swim back to shore.

A Spitfire MK I carried 685lbs worth of guns, ammo, gun sight, radio, etc. 84 imp gallons of fuel (100-101 us gal? 646lbs). Powerplant weight was 2035 with WOODEN fixed pitch prop and UNPROTECTED TANKS and NO OIL ( 54lbs) it had 880hp for take-off. No armor or bullet proof glass.

Light weight piston engine fighters ALWAYS turned out to be a waste of design time and effort, coming up lacking in armament and overall performance. With things like the Caudron C.714 - Wikipedia, the free encyclopedia a result.

 

[tomo pauk]

1. Purpose of the thread is not to prove that lightweight fighters would trump their heavier opponents.
2. As in 'what was the best long-range gun' thread in or WW2 forum - it's about a design that is supossed be better than others.

Spitfire just won't cut in here, but VG-33 might.

 

[Shortround6]

1. Light weight fighters don't trump heavier opponents, they just provide targets for them.
2. Long range artillery pieces had a purpose, they may have been expensive and hard to move but they did a job nothing else could do. Light weight fighters have no purpose.

Spit MK I weighed 5875lbs all up, 4290lbs empty? in summer of 1939. MS 406 weighed 4189lbs empty, 5,394lbs normal gross and 6,000lb max. D. 520 weighed 4,608lbs empty and 6179lbs max loaded. VG-33 4,519lb empty, 5,856lbs normal loaded and 6,393lbs maximum. Bf 109F-3 went 4,330lbs empty and 6,054lbs loaded.

Please define "light weight" as these are pretty much "normal" weight fighters by any but American standards.

 

[tomo pauk]

Fair enough. I'll edit the 1st post accordingly - so even the -33 is out of question

 

[Juha]

Hello Tomo
how about something like Vickers F.5/34 Venom, 625hp Bristol Aquila, 8 7.7mm mgs, very manoeuvrable, 312mph at 16,250 ft, AUW 4,150lb wing area 146sq ft, span 32ft 2in, lenght 24ft 2in. Weak points were engine, unreliable and no other military users, so Bristol had not much interest to perfect it, a bit like RR Peregrine and because of its smallness not much growth potential.

Juha

 

[buffnut453]

Don't know the specs for the CW-21B but wasn't that designed from the outset as a lightweight fighter (IIRC the term "interceptor" was used because of its rate of climb).

 

[parsifal]

The world leaders in lightweight fighters have to be the japanese. These certainly were not cannon fodder in 1940. I dont know if they fit all the criteria, but at 4000 lbs gross weight, versus roughly 6000 lbs for a spit, the zero has to be close to specification.

What cant be achieved is a lightweight fighter that provides everything that a heavier fighter does. Something has to give. in the case of the zero it was protection.

Moreover, the concept of the lightweight fighter has never quite been eliminated by tyechnology. At the end of the war the US had developed a lightweight fighter (I forget the designation) was very effective.

In the 50s, ed Heinemann chief advocate of this design concept (and certainly not deserving to be thrown out of an aeroplane 50 miles out to sea....despite what you air force boys would like done with him) designed aircraft like the A-4 that very much fitted into this concept. This philosophy was further extended into aircraft like the f5(e) freedom fighter , the MiG-21 and the F-16, Sepecat Jaguar all quite successful in their own ways.

 

[buffnut453]

Hmm...wouldn't have included the Jag in that list. It started out life as an advanced trainer but, courtesy of requirements creep, ended up as an under-powered ground attack aircraft.

 

[Shortround6]

The world leaders in lightweight fighters have to be the japanese. These certainly were not cannon fodder in 1940. I dont know if they fit all the criteria, but at 4000 lbs gross weight, versus roughly 6000 lbs for a spit, the zero has to be close to specification.

The early Zero (A6M2 model 21) had an empty weight of 3700lbs, loaded weight of 5313lbs and a max gross of 6164lbs. I am not sure that an empty weight of 86% of the Spitfire's really moves it into another category.

What cant be achieved is a lightweight fighter that provides everything that a heavier fighter does. Something has to give. in the case of the zero it was protection.

At the weights being quoted here NONE of the fighters had protection except the 109. The weights for the Spitfire are before protection was fitted.

Moreover, the concept of the lightweight fighter has never quite been eliminated by tyechnology. At the end of the war the US had developed a lightweight fighter (I forget the designation) was very effective.

Light weight US fighter? You mean the F8F Bearcat? at 7070lbs empty or the P-51H at 7040lbs empty?

In the 50s, ed Heinemann chief advocate of this design concept (and certainly not deserving to be thrown out of an aeroplane 50 miles out to sea....despite what you air force boys would like done with him) designed aircraft like the A-4 that very much fitted into this concept. This philosophy was further extended into aircraft like the f5(e) freedom fighter , the MiG-21 and the F-16, Sepecat Jaguar all quite successful in their own ways.

I believe I said piston engine light fighter.

The Power to weight ratio of piston engines was much closer to each other and in fact the larger engines tended to be better than the smaller engines.
AS Jet engines matured or developed the power to weight ratios were all over the map. A mid 50s or late 50s jet engine could deliver the same power as an late 40s or early 50s engine at 1/2 to 1/3 the weight which offered all kinds of opportunity to design small high performance aircraft, like the Folland Gnat. As an example the engine in a F-86 weighed about 2700lbs and gave about 5800lbs thrust dry, a R-R Nene weighed about 1550lbs for 5000lb of thrust while the Bristol Orpheus offered 4850lbs of thrust for under 1000lbs of weight and the J-85 engines in the F-5 freedom fighter offered 3850lbs thrust (with after burner) for just 525lbs (with after burner). Let's think about that last one shall we, 3850lbs thrust for less weight than a Lycoming 380hp IGSO-540 6 cylinder piston engine (dry weight with no propeller).

The Much better power to weight ratios of the newer jet engines offered opportunities that the older piston engines never could. In 1939-41 the better piston engines all offered power to weight ratios of about 1.1-1.3 pounds per HP. If somebody had a special engine that could offer .8-.9 lbs per HP for a 750-900hp engine perhaps a light fighter could have been made but the 750-900hp engines (what few there were) had worse power to weight ratios than the 1000-12000hp engines. With fixed weights of pilot, protection, radios, instruments and such a "light" fighter was devoting a higher percentage of it's weight to the engine and pilot/cockpit area than a larger fighter would. The French tried hard and had 4-6 planes in the 4000lb gross (not empty) area in 1938-1940.

 

[parsifal]

With regard to loaded weights, the loaded weights of an A6M2 model 21 was 5213 lbs. The max loaded weight for a spit Vb, its contemporary in time was 6770lbs. Theres a 30% difference in weight there, plus the Zero has a much greater percentage of it weight devoted to fuel does it not.

In concept the Model 21 is very much the lightweight fighter...small fuel efficient motor, airframe cut down and reduced in weight to the absolute minimum, adequate armament, it was an aircraft of compromises, but it worked. As you say it does not meet all the criteria of the thread.

One to consider might be the Martin Baker MB-2. First flight was 1938, it reached 305mph, carried 8 x 0.303 in mgs. Powered by a 1000hp Napier Dagger engine. Max loaded weight was about 5500 lbs.

 

[Shortround6]

The Criteria of the thread do not make sense. As proposed, the Criteria call for a plane to be introduced into service in 1940, the weight limits proposed are for perfectly "standard" gun loads (if not higher than standard) , perfectly "standard" ammo loads (if not higher than standard) , perfectly "standard" fuel loads, the addition of armor and protected tanks which only became standard in the second half of the year. All this combined with a SUB-standard engine/powerplant and the result defined as a "light" fighter. The performance of such a combination could hardly fail to be worse than either a "standard" fighter or a proper "light" fighter that sacrificed payload in addition to powerplant in order to gain performance.

AS for this comment. "the loaded weights of an A6M2 model 21 was 5213 lbs. The max loaded weight for a spit Vb, its contemporary in time was 6770lbs" may be true but the 230lb difference in fuel is compensated by the Spitfires double the weight of armament, protection and powerplant offering 30-40% more power.

The Martin Baker MB-2 helps show the concept for what it is. 5500lbs with a fixed pitch two blade prop, a top speed of 305mph (perfectly fine in 1938, a deathtrap in the second half of 1940), climb of 2200f/m, no armor, unprotected tanks. A 3 blade variable pitch prop could improve the climb quite a bit but that increases the weight ( Hurricane carried 58lb of ballast to balance even a 2 pitch prop), adding several hundred pounds of protection puts the thing mighty close to 5850lbs. With what advantage over even a Hurricane let alone a Spitfire? Better than an armed Miles Master trainer for sure but not really a first class fighter and not much cheaper than a first class fighter when fitted out,

 

[tomo pauk]

The criteria for thread does make sense. The engine choice (under 900 HP) can be looked as if it would not requiring any 'major' engine to be allocated for it (major as Merlin, or DB-601, or Jumo 211), and there was plenty to choose between 750-900 HP. For a 'minor' country, that might mean the only engine available - not everybody was able, or was allowed, to purchase Spitfire or the 109. We can look at Italy, Japan, Soviet union, let alone Poland, Yugoslavia, Holland, Belgium, Romania - the 'fighter' (or any) engine of 1000+ HP was almost out of the question for them prior 1940/41, and they were producing fighters. So we could 'design' a fighter for those countries, too.

Again, this is not the thread that aims to prove that light fighter is better than standard one.

 

[Shortround6]

It is not that the Light fighter would be better, it is that the light fighter is so much worse that any other option using a full power engine.

Any country that can build a first class fighter is simply wasting pilots by putting them in a second class aircraft.

Countries that used 750-900hp engines skimped on armament and protection in order to try for Performance. Italy, when using 840hp radials used a pair of 29 kg machine guns with 65kg of ammo (or under). The armament of the Oscar was even less. Soviet planes AFTER the I-16 went to about 7,000lbs gross. Most of the Minor countries planes of 1939-40 were armed with 4-6 rifle caliber machine guns, roughly 45-70kg of guns not 90-135kg of guns.

 

[gjs238]

Messerschmitt Me 163 ?
(trying to think out of the box here)

 

[tyrodtom]

A Me-163 was small, but it wasn't lightweight. Empty weight was 4200 lb. a lot of weight for it's size, only 19 ft long.
Takeoff weight was over 9000 lbs, it was a flying fuel tank.

 

[parsifal]

Flying bomb perhaps

 

[krieghund]

If the A6M2 were to be powered by the Kinsei 44 rather than the Sakae 12 the extra power could have meant room for armor. This would have matured to the Kinsei 54 which would have been the the same weight as the A6M3 Model 22 but better performance and of course the A6M8 with the Kinsei 62 would have been flying in early 1943 instead of 1945.

I agree that the Zero meets the intent of this thread.

 

[tomo pauk]

What would be the weight of such a Zero (we delete CV gear)?

added: with more than 900 HP, Zero is a tad out of the bounds here