Make-A-Plane Palooza: Late war / post war superprop fighters!

[TM06]

Guys, gals, non-binary pals, I welcome you all to my
Make-A-Plane Palooza challenge!​

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This is going to be a collection of thought experiments where forum members can flex their creative muscles and think up their own ideas of aircraft (And maybe other military vehicle types if people want it!) dedicated to a specific theme!

The rules are simple:

1. The vehicle in question must match the theme of the thread. For example, this thread is dedicated to superprop fighters from 1944~1950, meaning high performance bombers or attack aircraft are not allowed.
2. Users must pick a nation and stick to what that nation had available within the time frame.
3. In concert with rule 2, users must write up a short alternate history story describing their creation.
4. An AutoCAD of the aircraft is preferred, but not required.
5. And most importantly, this is just for fun!

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As you can glean from the heading, this thread's theme is superprop fighters! The definition of superprop varies from person to person, but I've settled on a relatively robust definition that I personally use.
The definition is as follows:

• The aircraft must be capable of at least 700 kph / 435 mph in level flight.
• The aircraft must have a climb rate of at least 18-20 m/s.
• The aircraft must have a forward facing armament with a one-second-burst-mass of at least 3 kg/s.
• The aircraft cannot use jet engines or mixed propulsion.

If the aircraft meets these four requirements, I personally consider it a superprop. With that addressed, get those creative juices flowing!

 

[Howard Gibson]

Why no more than 5500kg? If I want to use an R4360 engine, keeping the mass below 5500kg could be a challenge.

 

[TM06]

Why no more than 5500kg? If I want to use an R4360 engine, keeping the mass below 5500kg could be a challenge.

It's not a hard rule - note the line "if it meets at least three of the four requirements, I consider it a superprop." Those qualifications are just what I personally consider to define a superprop, and others may have different requirements. And besides, that challenge is part of what makes this fun
I've decided to remove the weight limit. Go ballistic, folks!

 

[Howard Gibson]

My problem with all this is that superprops actually got built. How would my superprop be different from any of the Hawker Furies, Supermarine Spitefuls, North American P51Hs, Republic P72s, and the various souped up Vought Corsairs, including the one with the R4360? Grumman Bearcats could be fun if you can install a bigger engine. Canard pushers like the Kyūshū J7W Shinden could be interesting, but they built two of them!

The elephant in the room is jet fighters. The superprops wound up not mattering to anybody. What happens if jet technology does not happen?

The USA develops the R4360, with turbochargers. Great Britain works on the Bristol Centaurus and the Rolls Royce Crecy, and they add two speed superchargers to the Napier Sabres. Rolls Royce did not go nuts souping up Griffons.

Another elephant in the room is top speed. In the absence of jet engines, the top speed of piston engined aircraft is limited by their propellers to around 530mph (850kph). The newer, bigger engines will improve acceleration and climb rates, but they will asymtotically approach that maximum propeller speed. Now, bombers become interesting. We make the bombers more powerful, and they asymtotically approach 530mph. If you are in a fighter intercepting bombers, you are closing slowly on something with defensive armament. Effective WWII interception tactics took advantage of the bombers' much lower top speeds. If the bombers approach at civilized altitudes, fighters can climb up above them and make diving attacks. If the bombers come in at high altitude, the fighters cannot get way up above them.

This brings in some technical issues. Your superprop fighters are going to get shot at and hit by 20mm cannons at the very least. They require very heavy frontal armour. Radial engines at the front of the aircraft may not be functional. Your 5500kg mass limit is just not functional. Weapons and sighting systems that are effective at long range will be useful -- 57 or 75mm long barrelled cannons anyone? How about a superprop Bolton Paul Defiant? Flying air superiority over battlefields at lower altitudes, fighters will not have speed advantages. WWII hit and run tactics will not work. Acceleration, climb and manoeuverability will be the critical characteristics of your superprops. Perhaps the requirements for interception and air superiority are so different that both cannot be met by a functional fighter aircraft.

Bomber technology will be affected too. Precision bombing from 40,000 to 50,000ft is not feasible if you are being attacked by flak and fighters. Everybody will develop remote, steerable bombs like the Fritz_X. There will be a battle to mess up the radio communications with the bombs. Do the superprop interceptors need a guy in the back seat operating electronics? Can a superprop fighter fly below the bombers and lay a smokescreen so that the bomb aimers cannot see their targets?

How about a remote controlled aircraft controlled from a nearby two-seat interceptor? It flies into the bomber formation and it explodes, taking a couple of bombers with it.

 

[z42]

As mentioned, the P-51H's, Hawker (Sea) Furies etc. are well trodden territory. For a slightly(?) unconventional take:

With jets posed or in the process of taking over the short range fighter missions any day now, the UK Air ministry still sees a point for one last long range prop fighter, primarily targeting escort and strike missions, including a two-seater variant with a radar operator for night fighter missions. Due to the desire for a combination of both range and power, the in development Napier Nomad is chosen as the powerplant (tl;dr: A 12-cylidern diesel two stroke mated with turbocharger/turbocompound unit. For the Nomad II about 3150 hp at a weight of 1620 kg).

Due to the desire to provide good vision for the pilot, and room for radar antennas, as well as avoid any gun convergence or synchronization, a pusher prop configuration is chosen. Counter-rotating props are chosen to limit the prop diameter compared to a single prop of equivalent power. This also lends itself well to a tricycle style landing gear.

For armament the Aden cannon is still in development, so 4x20mm Hispano Mk V's are chosen instead, mounted in the lower part of the nose.

No CAD drawings available, sorry. And I'm not committing to any particular performance numbers either. Due to the power of the engine it should be capable of the 700km/h limit assuming an decent job on the aerodynamics.

 

[Shortround6]

The F4U-5 hits all of the boxes.
So does the F8F-2.
They were some of few 1946-1950 fighters made in Quantity (several hundred) that used a new engine.
The engine used weighed 2700lbs (in the F4U-5) or about 400lbs less than the Nomad. They carried four 20mm M3 cannon (American equivalent to the British Hispano MK 5).

The F4U-5 engine shows a problem, it required a lot of airplane to hold the intercoolers and duct work. It also had about the best performance at altitude.
The F4U-5 carried the same guns as the F8F-2 but it carried a lot more ammo. It also had better performance higher altitudes and it had more range.
It was also heavier

 

[SaparotRob]

We'll need a P-39.

 

[Howard Gibson]

In response to the original post...

Assume we have bombers that cruise at 500mph at 40,000ft and that are defended by turrets with 20mm cannons. We are British, and will be using British hardware.

Our aircraft is an interceptor what will chase these bombers and close slowly in on them. We expect to be hit by 20mm cannon fire. We want to destroy the bomber with a short burst of fire, preferably from outside the effective range of the 20mm cannons. Fixed armament can generally be bigger and heavier than whatever is mounted flexibly, or in a turret.

The Miles Mangler is a canard pusher. Frontal armour will protect the pilot, the radiator and engine from 20mm cannon fire. The wings will be relatively long and thin for maximum climb rate and performance at 40,000ft. The cockpit will be pressurized, and there will be a bubble canopy. The aircraft will have enough range to chase and catch the fast bombers. We need to control size and weight.

The engine will be a Napier Sabre with a two-stage supercharger, putting out 3000+ horsepower. The radiator will be buried in the fuselage behind all the armour plate. It will be fed by air ducts, as recommended by F. W. Meredith. Meredith's report is mostly about burying the radiator and feeding it through small duct openings. Using the radiator to generate thrust is a single sentence at the end of his report. Protecting and feeding a radial engine sounds complicated to me.

Its armament will be a pair of Vickers 40mm S cannons. These were used by tank busting Hurricanes in the desert. The Vickers S fires at 100 rounds per minutes. It uses a 15 round magazine and it has a muzzle velocity of 1870ft/sec. We want to increase the muzzle velocity by a lot, and the magazine size if possible. We will use a fancy gyro gunsight so that we can make deflection shots from outside the ranges of the defending 20mm cannons. The US M4 37mm cannon sounds like a really good alternate weapon.

 

[Howard Gibson]

As mentioned, the P-51H's, Hawker (Sea) Furies etc. are well trodden territory. For a slightly(?) unconventional take:

The original Hawker Fury was a biplane. The next one was a land-based "lightweight" fighter with a Napier Sabre_VII, which did 485mph at 18,500ft. Note that altitude. Most fast WWII aircraft were flying in thin air somewhere above 25,000ft. Hawker Sea Furies were awsome, but that awsome.

 

[PFVA63]

The F4U-5 hits all of the boxes.
So does the F8F-2.
They were some of few 1946-1950 fighters made in Quantity (several hundred) that used a new engine.
The engine used weighed 2700lbs (in the F4U-5) or about 400lbs less than the Nomad. They carried four 20mm M3 cannon (American equivalent to the British Hispano MK 5).

The F4U-5 engine shows a problem, it required a lot of airplane to hold the intercoolers and duct work. It also had about the best performance at altitude.
The F4U-5 carried the same guns as the F8F-2 but it carried a lot more ammo. It also had better performance higher altitudes and it had more range.
It was also heavier

Hi,
That's interesting to know. When I first saw this thread one of my initial thoughts was to take the engine from an F8F and build a little bit larger airframe around it to give it more range and firepower or ammo etc, but from your post I see that the F4U-5 appears to kind of already have done that.

As such, I guess the other thought that I would maybe consider would be to take the engine from the Sky Raider or Martin Mauler and try to build a smaller/more dedicated fighter around it, if possible.

Making a quick look at some engine info that I have it appears that;

• a P&W R2800-32(E) might weight about 2300 to 2360lb dry
• a CW R4300-60 might weigh about 3450lb dry
• a CW R3350-26W might weight about 2822lb dry

So even if a smaller airframe were designed around one of these last two engines listed above, it would probably still result in a larger plane than the F4U-5 though it might still be interesting to look into it further.

For reference here is a plot of several US WWII era single engine Trainers, Fighters, and Attack aircraft showing their notional Basic Mission Gross Wt verses the base weights of their specific engine, that hopefully helps show how much lighter a pure fighter can be in comparison to a dedicated attack aircraft with similar sized powerplants.

Regards

Pat

 

[Howard Gibson]

Another response to the original post.

The bombers still are doing 500mph at 40,000ft, and they are well defended by turrets with 20mm cannons. There are no jet engines.

We still are British. A stern chase of the bombers is too dangerous given the defensive armament, especially if the bombers fly in formation. We want to form up beside the bombers about a mile away, and use a small, explosives packed, rocket powered aircraft as our primary armament.

The Westland Wolverine is a conventional layout, twin-engined, with a two-man crew. The cockpit is pressurized. It is armoured like a conventional WWII fighter, with armour plate located behind the aircrew. Again, the wings will be relatively long and thin for maximum high altitude performance.

The engine will be either a two-stage supercharged Napier Sabre, or a Rolls Royce Griffon. They go nuts souping up Griffon engines because there are no jet engines. We use an efficient radiator system like those in the de Havilland Mosquitos and Hornets.

Our primary weapon will be a remote controlled missile weighing no more than 500lb. A hundred pounds of explosive should be dangerous even exploding in proximity. The missile will have ten minutes of fuel. They will be stored in a bomb bay in the aircraft, located at the aircraft centre of mass. We want to carry at least three of these things, to allow for the inevitable misses, and missiles destroyed by bomber guns. We want to launch them one at a time while keeping the aircraft flyable. We don't want them to affect aerodynamics. The missiles will have folding wings, which will pop out after launch.

There will be a pair of 20mm Hispano cannons mounted in the wing roots.

There will be radar in the nose of the aircraft.

The pilot will fly the aircraft and fire the 20mm cannons. The back seater will operate the radar and any other electronics, and launch and direct the missiles.

American escort fighters were effective in WWII because the Germans and Japanese did not develop two-stage supercharging. American bombers flew at high altitudes that suited American escort fighters. Nobody will have that advantage over us. The Westland Wolverine will be capable of dogfighting anything with the range to keep up with the bombers.

 

[Sisu]

It's worth pointing out the success of this re-engined Sea Fury in post-war air racing. It is a full dual control version with a well engineered installation of a 4360 with a Skyraider prop. A big well nannered airplane with superb aerodynamics and a demonstrated ablilty to reliably run 100mph faster than a Centaurus Fury or stock Mustang under Reno race conditions. So big aiplane with huge power (up to 4000 hp fairly easily), sophisticated late-war aerodynamics, plenty of room for fuel and ordnance, and obvious capability for a second seat if desired. Could this answer the question without all the uncertainty and development time of the more exotic ideas we're seeing here?

 

[Shortround6]

Our primary weapon will be a remote controlled missile weighing no more than 500lb. A hundred pounds of explosive should be dangerous even exploding in proximity. The missile will have ten minutes of fuel. They will be stored in a bomb bay in the aircraft, located at the aircraft centre of mass. We want to carry at least three of these things,

Needing a mid 50s missile might be stretching things a bit.

Nord AA.20 - Wikipedia

en.wikipedia.org

295lbs
warhead weight 51lbs and warhead weight and HE weight are NOT the same thing.
Range 2.5 miles.
Speed Mach 1.7 or 563 m/s. Please note that if that speed is maintained you have about 4 seconds of flight.
Guidance= track by flare and command guidance (joystick/radio).

It worked, kind of, and it used 1950s technology to do it.
Trying to use even 1940s rocket motors and electronics is going to be hard. Everybody knew the theory, getting the theory to work in the real world was a problem.

 

[Howard Gibson]

It worked, kind of, and it used 1950s technology to do it.
Trying to use even 1940s rocket motors and electronics is going to be hard. Everybody knew the theory, getting the theory to work in the real world was a problem.

The Hs293 and the FritzX had flares on their tails. The bomb aimer used a remote control, and simply imposed the flare on the target. It would nice to hit the bomber, but close counts in horseshoes, hand grenades, and high explosives going off near aircraft. If you force the bomber formation to spread out a bit, there is a better chance for the Miles Mangler to get in and do something.