Light fighters alternatives, 1935-1945 (6 Viewers)

[GrauGeist]

Why wasn't the rudder just made bigger ? Was it impossinble afterwards ?

View attachment 902503

Just looking at the image, it appears that the fuselage is too short and the CoG is too far forward, so the outboard vertical stabilizers were there to help stabilize the aircraft's flight characteristics.

Plus, it's French...

 

[topspeed]

Just looking at the image, it appears that the fuselage is too short and the CoG is too far forward, so the outboard vertical stabilizers were there to help stabilize the aircraft's flight characteristics.

Plus, it's French...

Of course, but is not what I asked...I asked if the existing rudder...were they unable to increase the size of that ? Those little finns added 4 intersection poins...thus increase the interference drag dramatically thus lessening the top speed.

 

[GrauGeist]

Of course, but is not what I asked...I asked if the existing rudder...were they unable to increase the size of that ? Those little finns added 4 intersection poins...thus increase the interference drag dramatically thus lessening the top speed.

ok, yeah...so tell me you have zero clues about aerodynamics without actually saying you have zero clues about aerodynamics.

 

[topspeed]

ok, yeah...so tell me you have zero clues about aerodynamics without actually saying you have zero clues about aerodynamics.

I am a fluid dynamics teacher at the university...soon. You have no clue....right ?

 

[bf109xxl]

I am a fluid dynamics teacher at the university...soon. You have no clue....right ?

And I am the dictator of the universe...soon. But no one has a clue...

 

[Elan Vital]

A friend of mine summed up what was in the text of Philippe RICCO's article on CAO 200:

First flight of the CAO 200 on January 30th 1939, flown by Pierre Nadot.
It reached 489 km/h after February 8 (unknown date) with a 860 PS Hispano-Suiza 12Y-31.
Towards July (unknown date) 545 km/h at 6.000 m with exhaust thrust giving an extra 16 km/h, indicating that the aircraft had been fine-tuned and possibly improved aerodynamically (new propeller?) and reached 530 kph without exhaust thrust.

The "spec sheet" gave the following details

446 km/h at SL (500 km/h with 1200 PS 12Y-51)
490 km/h at 2.000 m
535 km/h at 4.000 m
550 km/h at 4.500 m (resp. 610 km/h)
540 km/h at 6.000 m
500 km/h at 8.000 m
367 km/h at 9.300 m

2.000 m in 2 min 27 s
4.000 m in 4 min 50 s
4.500 m in 5 min 35 (5 min with 12Y-51)
6.000 m in 7 min 50 s
8.000 m in 13 min 45 s
9.300 m in 20 min 45 s

The accuracy of the figures given would indicate that they were genuinely measured, but possibly not with the armament as the pictures don't seem to show the cannon until the last trimester of 1939. The estimates given with the 12Y-51 are misleading as 1200 PS was only a takeoff setting which was actually reduced to 1100 PS in the end, while the actual altitude power was 1000 PS, giving a theoretical max of about 578 kph.

Note the 4500m critical altitude. It seems that the 6000 m value was probably with a different propeller, as French trials with different propellers often showed considerable changes in the critical altitude as seen on MS-405 and Bloch 150. The higher critical altitude was probably achieved at the expense of climb rate and is thus not representative of the configuration of the production design.

People who described CAO-1000's wind tunnel model say that it no longer had the small rudders, which were originally added because the main rudder had been found insufficient. This shows that CAO understood the issue and fixed the main rudder at some point.

In any case, I don't think this aircraft is worth discussing here as it was not a light fighter by any means.

 

[z42]

I do not know of any air-cooled inline engines that were used in naval aircraft but my guess is that air-cooled inline offered the perfect mix of characteristics for a lightweight carrier aircraft.

Short answer: No.

Longer answer: We had a thread about this a few years ago: Air cooled inline engines - a missed opportunity? . The takeaway being that air cooled inline engines have several undesirable qualities which make them not as good a choice as one would first think. The historical mainstream choices of either air cooled radial engines or liquid cooled inlines were arguably the better options.

 

[Shortround6]

The takeaway being that air cooled inline engines have several undesirable qualities which make them not as good a choice as one would first think. The historical mainstream choices of either air cooled radial engines or liquid cooled inlines were arguably the better options.

That certainly seems to be the case.
The Air cooled V-12 engine that saw the most use was Isotta-Fraschini Delta of around 750hp (exact models differed a bit) of 26.7 liters which powered two Caudron C.R. 760 prototypes.
If P&W and used 12 cylinders from the R-1830 engine they would have had a about a 26.7 liter engine running at about the same rpm.
Better fuel and better cooling helped but 12 P&W cylinders would be good for 900hp at about 4000 meters, assuming you can keep the V-12 cool.
That is not enough to make any of the liquid cooled engine makers switch over. An air cooled V-12 was always going to longer in length than a liquid cooled on because you have to space the cylinders further apart to fit in the cooling fins. Which means a longer crankshaft with more torsional vibration problems.

In any case, I don't think this aircraft is worth discussing here as it was not a light fighter by any means.

Certainly not by the current French standards These were about 3000lbs or less empty and close 4,000lbs loaded.
Around 5,500lbs was the area of the French standard fighters of day with questionable protection and perhaps questionable electronics.

 

[tomo pauk]

The Air cooled V-12 engine that saw the most use was Isotta-Fraschini Delta of around 750hp (exact models differed a bit) of 26.7 liters which powered two Caudron C.R. 760 prototypes.
If P&W and used 12 cylinders from the R-1830 engine they would have had a about a 26.7 liter engine running at about the same rpm.
Better fuel and better cooling helped but 12 P&W cylinders would be good for 900hp at about 4000 meters, assuming you can keep the V-12 cool.

If one has no high-octane fuel and no reasonable expectation of 'trick superchargers' with intercoolers, and not even the 2-speed drives, making a small engine and expecting to play with the big boys is a recipe for a failure. IOW, if I-F (or other people) were to made a 35-40L V12 air-cooed engine with 2-speed S/C, that might've worked well as a military engine.

Instead of P&W, let's transplant the Wright and R-1820 or R-2600 cylinders into a V12. Gets us to 1200-1300 HP at 4-5 km, without any fancy S/C, but with a high-oct fuel. Or, the BMW 801 as a part donor, for the same result. Or, the Bristol Pegasus for 1100-1200 HP.
Added benefit for the American and British enghines - easy use of exhaust thrust. The early introduction of a better fresh air intake might also happen, for extra 15+- percent HP at higher altitudes.

 

[tomo pauk]

I do not know of any air-cooled inline engines that were used in naval aircraft but my guess is that air-cooled inline offered the perfect mix of characteristics for a lightweight carrier aircraft.

A V8 air-cooled engine might've worked in the 1930s? Use something with a big cylinder (talk Cyclone or Pegasus) as a parts donor, and one can realistically get 750-800 HP at 4+ km of altitude. Not as fancy as a 1000+ HP Merlin or DB 601, but in the ballpark of HS-12Y-31 or the last Kestrels, and much better than the best Jumo 210, all while not paying the price of the drag of a 9 cyl engine of the day.

Added: a V8 is typically at 90 deg between the banks, so it should be very easy to design the engine for the motor-canno capability.

 

[Shortround6]

A V8 air-cooled engine might've worked in the 1930s?

Dec of 1939?
Single speed Pegasus in 1938 was offering 925hp at 3,050 meters.
V-8 is offering 824hp?
and the elephant in the room

146mm dia pistons. How much space do we need between the cylinders for the cooling fins?
Spacing on a Merlin

152mm pistons.
Old Cyclone cylinders.

Please allow for about 3/16 in (4.5mm) minimum for air flow and a sheet metal baffle between cylinders. Keeping the heads cool is the main problem.
How tightly can you really squeeze the cylinders?
And thus how big does the crankcase and crankshaft half to be?
Radial was a very good way of getting a lot of cylinders into a small volume, even if wide.

 

[Admiral Beez]

It's the lightweight heavy fighters that take the win. Twin engines, heavy armament, but light enough to compete against single engined fighters. Such as the Lockheed P-38.

 

[tomo pauk]

Dec of 1939?
Single speed Pegasus in 1938 was offering 925hp at 3,050 meters.
V-8 is offering 824hp?

The 2-speed version did 880 HP at 4.4 km.
But for a lightweight fighter - good, we are matching the Italians and French main fighter's engines.

How tightly can you really squeeze the cylinders?
And thus how big does the crankcase and crankshaft half to be?

The engine itself should be shorter than even the Merlin or the HS-12X.

 

[Howard Gibson]

Why wasn't the rudder just made bigger ? Was it impossible afterwards ?

View attachment 902503

The problem with convergent development is that there are only so many places to put radiators on an aircraft with liquid cooled engines.

• In front of the engine at the front
• Underneath the engine at the front
• Under the fuselage just behind the pilot
• Under the wings close to the wing roots

On the Mustangs, the radiator scoop does not stick down much. This is because the radiators are inside the fuselage, contributing as little as possible to the aircraft's frontal area, as recommended by F.W. Meredith. The CAO 200 has a lot more resemblance to the Hawker Hurricane.

 

[tomo pauk]

The problem with convergent development is that there are only so many places to put radiators on an aircraft with liquid cooled engines.

• In front of the engine at the front
• Underneath the engine at the front
• Under the fuselage just behind the pilot
• Under the wings close to the wing roots

No love for the leading-edge radiator? Look at this beauty.

On the Mustangs, the radiator scoop does not stick down much. This is because the radiators are inside the fuselage, contributing as little as possible to the aircraft's frontal area, as recommended by F.W. Meredith. The CAO 200 has a lot more resemblance to the Hawker Hurricane.

Agreed.
It also took a while for the people (some, not all - a good deal of them didn't do it) to leave a gap between the fuselage and the radiator entry, so the boundary layer is not sucked in.

 

[Shortround6]

Strangely enough the much-maligned Hurricane, while mounting the radiator below the fuselage, did use a rather nice boundary splitter/diverter.

Not all chin radiators were the same either.

only about 1/2 the radiator is lower than the wing bottom adding to frontal area. Actual airflow/drag could very well be different.
P-40 often takes a lot of internet flak about its chin intake.

Change from P-40 to P-40B. Note where the bottom of the wing is.
Also note that on the P-40E, most of the radiator and fairing stayed the same. Due to the new reduction gear the propeller moved 6in higher creating the larger inlet. Frontal area stayed about the same.
Leading edge radiators were great for keeping frontal area down. Maybe not so good at getting Meridith effect? rear side of the radiator airflow may have been too tight (not long enough) and subject to turbulence? Just guessing.

 

[tomo pauk]

As once can expect, it took a lot of trial and error to get the radiators right, IOW with as low drag as possible. Even the praised Mustangs went through 4 - four - iterations of the radiator shape.
While the Hurricane's set-up might score points on the outwards looks, the much-maligned radiators of the Spitfire I (and probably on the II and V) were actually with a bit lower drag. Germans took a lot of time to come out with good radiators for the Bf 109, and I'm sure that there was still a lot of room for improvement, even if the actual room on the 109 was a scarce comodity to begin with.
As for the P-40, I'd say that the beard radiator was pretty good, both as the idea and execution, even if not as good as on the last XP-40Q.

 

[wuzak]

The problem with convergent development is that there are only so many places to put radiators on an aircraft with liquid cooled engines.

• In front of the engine at the front
• Underneath the engine at the front
• Under the fuselage just behind the pilot
• Under the wings close to the wing roots

On the Mustangs, the radiator scoop does not stick down much. This is because the radiators are inside the fuselage, contributing as little as possible to the aircraft's frontal area, as recommended by F.W. Meredith. The CAO 200 has a lot more resemblance to the Hawker Hurricane.

That is a few more options than air cooled engines have!

 

[wuzak]

Strangely enough the much-maligned Hurricane, while mounting the radiator below the fuselage, did use a rather nice boundary splitter/diverter.
View attachment 902645

But they didn't do that for the Tornado prototype, which failed and required moving the radiator under the nose.

Maybe they had some boundary layer diverter system internally, but I am unsure of that.