Light fighters alternatives, 1935-1945 (4 Viewers)

[z42]

Could we make a V-12 air cooled light fighter powered by the de Havilland Gipsy Twelve?

I'm sure we could, but would it be any good? Probably not, the 425hp that engine produced (per wiki) is too little even for a lightweight fighter.

Is there any advantage of a air cooled inline engine over a radial?

Smaller frontal area and, well, that's about it.

Limiting ourselves to just British engines, instead of the Gypsy Twelve we could pick, say, the Bristol Mercury. Comparing the specs on Wikipedia, the Mercury is on the market 12 years earlier, weighs slightly less, and produces 200hp more.

Bristol Mercury - Wikipedia

en.wikipedia.org

 

[tomo pauk]

Limiting ourselves to just British engines, instead of the Gypsy Twelve we could pick, say, the Bristol Mercury. Comparing the specs on Wikipedia, the Mercury is on the market 12 years earlier, weighs slightly less, and produces 200hp more.

Mercury was outfitted with the proper supercharging, so it was very useful engine even at high altitudes of the day.
A supercharger of the Gipsy Twelve looks as it the people were looking at the HS 12X and Y superchargers and said: we can do worse. But, being a bit more than a warmed-up ww1 tech, the engine power section was perhaps a full decades behind ... everything, and meagre supercharging was all it could take.

Perhaps a niche for the Gipsy Twelve might've been in the tank engines' compartments? De-rate it a bit so it can use the pool petrol.

 

[AerialTorpedoDude69]

Would the A5M be capable of catching the fighters that were attacking your bombers? Would its pair of 7.7mm machine guns stop a Hellcat from doing whatever it is Hellcats do? The Seafire LFIIIs were fast at low altitude, and they were armed with a pair of 20mm cannons.

It is not good enough to just keep up with the bombers.

That is a good point. For the sake of discussion, the time frame is 1942-43 before the Hellcat or Corsair became the most numerous naval fighter in the Pacific.

So is the concept of an ultra-light fighter feasible? Maybe during the first half of the war as a pure CAP fighter. Japan wasn't fully using three of its smallest carriers (the Hosho, Unyo, Taiyo). Together, its escort-class ships could have expanded the CAP at Midway or Coral Sea by around 68 to 90 Claude fighters (these ships could only fly biplanes or the Claude). A combat air patrol of such size would have overwhelmed the 18 or so SBDs that sank four carriers at Midway.

The USN success at Midway required waves of bombers pulling down the IJN CAP. By the time two squadrons of SBDs broke through, there were practically no Zeros providing cover.

Swede may not have actually downed his claims, but he survived the attack and preoccupied the Zeros who could have otherwise gone on to down other aircraft. Vejtasa's action was actually during the Battle of Coral Sea and he was deployed as auxiliary CAP and, it was three claims, btw.

Also at the Battle of Coral Sea, Lt. Lefla and his Gunner R3C Liska accumulated 7 enemy aircraft downed, five of which were in a single engagement. The other victories were on day two of the battle, where Lefla's SBD was deployed as auxiliary CAP.

If the IJN used its escort-class carriers purely as CAP, they could have added between 68 and 90 additional CAP fighters to its fast carrier strike force. This could have successfully defended against the two squadrons of SBD which managed to sink three carriers.

This is all academic though. Kido Butai went ahead of the slower main body to attack Midway. Yamamoto believed that he had the element of surprise and that the slower main body would be detected.

My argument here is that obsolete carriers and aircraft could have been put to good use at pivotal moments in carrier battles. Time and again, we see inadequately staffed CAP being dragged down to sea level while their carriers get obliterated.

Also, Leffla's kills are not fully backed by Japanese records. I'm not doubting his heroism. He was a true hero. But shooting down a fighter in a dive bomber is not easy even for the bravest and most skilled dive-bomber pilots.

 

[Shortround6]

Could we make a V-12 air cooled light fighter powered by the de Havilland Gipsy Twelve?

No.

Well, you could but the idea is to shoot down enemy airplanes, not provide target practice for the enemy.

The Bell XP-77 was similarly powered by the air cooled Ranger V-770. Is there any advantage of a air cooled inline engine over a radial?

And this shows the stupidity of the idea.
DH Gypsy King, 18.37 liter engine, 1058lbs dry (no hydraulic pump, air pump, vacuum pump or generator or?)
525hp for take-off.
425hp at 7750ft.
The engine is narrower (more streamlined) than a P&W Wasp (22 liters) in a P-26 but it is about 100lbs heavier and the Wasp makes 550hp at 8000ft.
Ranger planned for the XP-77 was vaporware at best. In 1938 the 640lb, 12.7 liter B series engine was offering 450hp from 0 to 2000ft.
In 1942 the weight had gone up to 730lbs and power had gone to 520 for take-off, rated power was 450hp 12,000ft in the C series engine.
They used a C series engine of the XP-77 because the D series was not ready yet. C series used was good for 520hp at 12,000ft. Problem was that unlike just about most other US engines of time the T-O (military) rating was only good for one minute and not 5 minutes.
XP-77 was supposed to get a D series engine (there 5 different D series engines with different superchargers) with a Szydlowsky-Planiol (SP) supercharger. Power claims were all over the place, like over 400hp at 26,000ft?
Post war the now 870lb engine was supposed to make 450hp cruise power at 22,500ft but only a few engines showed up. Also needed 100/130 fuel.
XP-77 with the fitted engine was fast for the installed power. It also sucked at climbing. Initial climb rate does not agree with the climb to 10,000ft numbers by a large margin.
Prototype also never got guns (or armor or???)

 

[Shortround6]

Perhaps a niche for the Gipsy Twelve might've been in the tank engines' compartments?

What do you have against the British tankers
Don't they have enough problems from 1939 to 1943?
An under-powered, hard to maintain, hard to cool engine in North Africa?

 

[Howard Gibson]

That is a good point. For the sake of discussion, the time frame is 1942-43 before the Hellcat or Corsair became the most numerous naval fighter in the Pacific.

So is the concept of an ultra-light fighter feasible? Maybe during the first half of the war as a pure CAP fighter. Japan wasn't fully using three of its smallest carriers (the Hosho, Unyo, Taiyo). Together, its escort-class ships could have expanded the CAP at Midway or Coral Sea by around 68 to 90 Claude fighters (these ships could only fly biplanes or the Claude). A combat air patrol of such size would have overwhelmed the 18 or so SBDs that sank four carriers at Midway.

The USN success at Midway required waves of bombers pulling down the IJN CAP. By the time two squadrons of SBDs broke through, there were practically no Zeros providing cover.

Would an A5M and its pair of 7.7mm machine guns be a reliable resource for shooting down Douglas TBDs? The A6Ms had a pair of 20mm cannons. US Navy F4F pilots were told to not to manoeuvre with A6Ms at speeds less than 300mph. The 270mph A5M has no chance against these tactics.

I brought up Seafire LFIIIs, however cheap they weren't, because the Royal Navy worked around their primitive (by '43 to '45 standards) engines by optimizing their superchargers for low altitude. These were formidable aircraft at low altitudes. There were no conditions in which an A5M could safely take on a correctly flown F4F or P40. Your lightweight fighter requires current performance under at least some conditions.

 

[tomo pauk]

What do you have against the British tankers
Don't they have enough problems from 1939 to 1943?

Not me.
One of their problems was lack of the engine of sufficient power.

An under-powered, hard to maintain, hard to cool engine in North Africa?

Under-powered? You've probably gotten that mixed up with what powered Matildas, Valentines and early cruisers.
If the engine is accepted as a tank engine by the late 1930s, that means a reasonable supply of spare parts and reasonable supply of trained mechanics by the time N.A. is in the cards.
A big fan, or two smaller ones should take care of cooling.

 

[Elan Vital]

Perhaps a niche for the Gipsy Twelve might've been in the tank engines' compartments? De-rate it a bit so it can use the pool petrol.

Not me.
One of their problems was lack of the engine of sufficient power.

Under-powered? You've probably gotten that mixed up with what powered Matildas, Valentines and early cruisers.
If the engine is accepted as a tank engine by the late 1930s, that means a reasonable supply of spare parts and reasonable supply of trained mechanics by the time N.A. is in the cards.
A big fan, or two smaller ones should take care of cooling.

I don't think it would be any better than Liberty here. Per Wiki (I know...), Gipsy King is over 2 meters long while Liberty was 1770mm long and Meteor 1470mm long. The Gipsy is shorter at least (assuming Liberty was still 1050mm tall in A13 Mk 1 and 2), but overall the lower displacement didn't translate to much space savings.

The output of 425/405 hp may not be maintained without the supercharger and an pool petrol, so there may not be much if any extra power over the 340 hp of the Liberty, which could be uprated.

The biggest issue by far is that the Gipsy is an inverted V12, so there may be severe accessibility and premature wear issues in a tank.

Now, sure, compared to Matilda II, Valentine and the A9/10 it at least gives a high ouput option, but so could many other 300-350 hp engines in British hands. The choice of a small commercial engine in the Vickers tanks was deliberate, and the designers of Matilda II simply didn't think there was any more powerful option they could get at the time.

 

[tomo pauk]

The biggest issue by far is that the Gipsy is an inverted V12, so there may be severe accessibility and premature wear issues in a tank.

Being the inverted engine might've been indeed the biggest issue, unless the engine is modified into the upright type.

The choice of a small commercial engine in the Vickers tanks was deliberate, and the designers of Matilda II simply didn't think there was any more powerful option they could get at the time.

The engine choice of the British tanks was more of trying to make the best from the bad hand the tank makers were dealt.
I don't buy the notion that designers of Matilda II didn't think that there was any more powerful option.

 

[tomo pauk]

I don't think it would be any better than Liberty here. Per Wiki (I know...), Gipsy King is over 2 meters long while Liberty was 1770mm long and Meteor 1470mm long. The Gipsy is shorter at least (assuming Liberty was still 1050mm tall in A13 Mk 1 and 2), but overall the lower displacement didn't translate to much space savings.

The length figures for the later two engines are without the reduction gearing and without supercharger.

 

[Shortround6]

The length figures for the later two engines are without the reduction gearing and without supercharger.

Very true, the Gypsy 6 was just over 1.6 meters long. No supercharger and no reduction gear. Aircraft engines do have a propeller shaft which does some extra length. They don't have flywheels or clutches though, but depending on transmission location perhaps they can be part of the transmission? In any case the Gypsy Kings length is not a problem.

Being the inverted engine might've been indeed the biggest issue, unless the engine is modified into the upright type.

This is the real problem, spark plugs and valve adjustment are at the bottom of the engine compartment. Getting access on an inverted engine is a very big problem for maintenance.
Something that the British did not pay enough attention to in the early tanks. Fixed by flipping the engine over? Certainly easier to pull ducts/baffles out of the way than try to get arms down to the bottom of a tank engine bay.
British tanks put the transmission/steering gear at back of the tank. Grants and Shermans could get access to the engine through hatches/doors at the back even if it meant unbolting the hatches/doors. Some British tanks used small hatches/access panels in the side in between the road wheels to reach certain things. Hopefully not often but such hatches/access panels are expensive to make and weaken the side/rear armor.
Proper engineering of cooling and engine access was NOT a high point of British tank engineering in the British cruisers until the A24s and later, maybe until the A 34 (Comet).
It took quite some time for the Churchill to get straightened out.

One of their problems was lack of the engine of sufficient power.

Tanks love torque. Liberty with 27 liters had lots and lots of torque. It didn't rev very well which limited horsepower. But the torque allowed the British to get away with using a 4 speed transmission. Germans with their 12 liter 265-300hp V-12s needed 6-10 gears in the Pz III & IV tanks. Crusader had more torque than an early Tiger tank (23 liter engine).
Using an 18.4 liter engine means a roughly 1/3 reduction in torque. Needs an extra gear or perhaps a lot more shifting and/or wear on the engine.
The 16 liter engine used in the Covenanter was mistake from the first pencil stroke on paper.

A big fan, or two smaller ones should take care of cooling.

Sounds simple, turns out it was one of big failings of the Crusader tank.
The A13s used a single big fan to cool the Liberty engine.
The tank theory guys said the hull was too tall, and they wanted a flatter hull to make a smaller target. They wanted to reduce the height of Liberty engine installation by 7in.
They had the best of intentions, what could possibly go wrong?
1st. The entire Covenanter Fiasco which came close to losing the war for the British.
2nd. the Crusader with the short Liberty engine, they screwed up the oil system on the crankshaft.
AND they went to 2 small fans instead of one big one which had worked OK in the Liberty A 13 cruisers.
It took several years and a host of modifications to get the drive system for the two fans to work. The system gave proper cooling (mostly) when it worked. Problem was the fan drive often broke and/or wore out very quickly. Using an open oiled chain drive with sprockets inside a tank was not a good idea in England. Using it in sands of NA was a disaster. Blowing sand filled air though the engine compartment is NOT a good idea.

 

[tomo pauk]

Tanks love torque. Liberty with 27 liters had lots and lots of torque. It didn't rev very well which limited horsepower. But the torque allowed the British to get away with using a 4 speed transmission. Germans with their 12 liter 265-300hp V-12s needed 6-10 gears in the Pz III & IV tanks. Crusader had more torque than an early Tiger tank (23 liter engine).
Using an 18.4 liter engine means a roughly 1/3 reduction in torque. Needs an extra gear or perhaps a lot more shifting and/or wear on the engine.

The way around the smaller torque of a smaller engine should be the greater reduction on the final drive. There is enough of extra RPM over the Liberty in order for the top speed to be still competitive.

But either the Liberty or the Gipsy 12 would've been plenty enough for the infantry tanks, even if the powerpack is tailored for the lower speeds.

The 16 liter engine used in the Covenanter was mistake from the first pencil stroke on paper.

Indeed.