F/A-12 A Air Superiority Strike Fighter

• Crew: 1
• Length: 15.32 metres
• Wingspan: 8.61 metres (with wingtip missiles)
• Height: 4.64 metres
• Empty weight: 4,989 kg
• Max fuel weight: 3,952 kg
• Max loaded weight (MTOW): 9,234 kg
• Powerplant: 1x Misech 101 afterburning turbofan
  -Dry thrust: 61.2 kN
  -Maximum military thrust: 62 kN
  -Wet thrust: 85 kN
• Maximum speed:
  - At sea level: Mach 1.2
  - Maximum: Mach 1.8
• Range: 941 nm
• Ferry range: 2,120 nm
  - With external tanks ~2,300 nm
• Service ceiling: 16,200 metres
• Rate of climb: 227 m/s
• Max g-load: -3.0g/+9.0g
  
• Guns: 2x 20mm cannon, 300 rounds each
• Hardpoints: 7 (4 underwing up to 2,200 kg each, 2 wingtip up to 1,500 kg each, 1 belly up to 3,000 kg)
• Standard recommended layouts:
  -6 air-to-air missiles
  or
  -4x range air-to-air missiles (2 underwing, 2 wingtip)
  2x air-to-surface missiles (underwing)
  or
  -4x air-to-surface missiles
  2x air-to-air missiles (wingtip)
• Bombs:
  Varied, up to 900 kg laser guided bombs
• Tanks:
  2x 544-550 kg external fuel tanks (underwing)
  1x 600-750 kg external fuel tank (belly)
• Avionics:
  Northrop Grumman AN/ALR-67(V) Radar Warning Receiver
  Emerson AN/APG-69
  15 thermal chaff
  Sanders Associates ALQ-144 IRCM

F/A-12 B Air Superiority Strike Fighter Naval Variant

• Crew: 1
• Length: 15.35 metres
• Wingspan: 8.78 metres (with wingtip missiles)
• Height: 4.74 metres
• Empty weight: 5,134 kg
• Max fuel weight: 2,109 kg
• Max loaded weight (MTOW): 10,002 kg
• Powerplant: 1x General Electric F414 afterburning turbofan
  -Dry thrust: 61.2 kN
  -Maximum military thrust: 62 kN
  -Wet thrust: 85 kN
• Maximum speed:
  - At sea level: Mach 1.2
  - Maximum: Mach 1.8
• Range: 941 nm
• Ferry range: 2,120 nm
  - With external tanks ~2,300 nm
• Service ceiling: 16,200 metres
• Rate of climb: 227 m/s
• Max g-load: -3.0g/+9.0g
  
  
• Guns: 2x 20mm cannon, 300 rounds each
• Hardpoints: 7 (4 underwing up to 2,200 kg each, 2 wingtip up to 1,500 kg each, 1 belly up to 3,000 kg)
• Standard recommended layouts:
  -6 air-to-air missiles
  or
  -4x range air-to-air missiles (2 underwing, 2 wingtip)
  2x air-to-surface missiles (underwing)
  or
  -4x air-to-surface missiles
  2x air-to-air missiles (wingtip)
• Bombs:
  Varied, up to 900 kg laser guided bombs
• Tanks:
  2x 544-550 kg external fuel tanks (underwing)
  1x 600 kg external fuel tank (belly)
  
• Avionics:
  Northrop Grumman AN/ALR-67(V) Radar Warning Receiver
  Emerson AN/APG-69
  15 thermal chaff
  Sanders Associates ALQ-144 IRCM

The F/A-12 is an air superiority and air strike fighter for both ground and naval applications. The F/A-12 is the major competitor to the F-11 Nimbus concept by Adversity Technologies. The F/A-12 was primarily designed as a modernization and improvement of the F-5 A Freedom Fighter, to present a lightweight, nasalized air superiority and air strike aircraft that could maximize energy maneuverability potential.

Design

The F/A-12 has a slender body with leading edge extensions on the wings, allowing for greater energy and low speed performance, as well as overall maneuverability. Two engines are fed by two inlets which lead to thrust nozzles which were designed to minimize thermal signature while maintaining an overall light weight, keeping the entire engine system under a set weight cap. While the straight inlets increase radar signature, they maintain overall goals of low maintenance to reduce costs.

Support structures in both the F/A-12 A and F/A-12 B use the high-strength 2024 aluminium alloy, constructed mainly out of copper. It was selected above other aluminum alloys, such as 7075 aluminium alloy, for it's increased reliability and well-stated use in other aircraft.

Aluminum Alloy 2024 composition

• Si: .5% (percent weight)
• Fe: .5%
• Cu: 1.2%
• Mn: .9%
• Cr: .1%
• Zn: .25%
• Ti: .15%

( http://www.aviationmetals.net/2024_aluminum.php )

Aluminum Alloy 2024 properties

• Density: 0.00276799047 kg per cm3
• Specific gravity: 2.78
• Melting point: 510 degrees celcius
• Modulus specs:
  - Elasticity Tension: 10.6
  - Elasticity Torsion: 4.0

( http://www.suppliersonline.com/propertypages/2024.asp )


Small amounts of materials in the initial prototypes were constructed out of low-cost NASA Aluminum Alloy 689247-T8, also mainly constructed out of copper.


Aluminum Alloy 689247 properties

• Cu
  5.85% (nominal weight percent)
  5.71% (actual weight percent)
• Mg
  .50%
  .50%
• Mn
  .30%
  .32%
• Zr
  .15%
  .15%
• V
  .10%
  .09%
• Fe
  .05%
  .06%
• Si
  .04%
  .05%

( http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1996092944.pdf
)

( http://www.makeitfrom.com/material-data/?f...u4Mg1-Aluminum)

However, initial tests proved that 2024 was efficient for the purposes of the F/A-12.


The F/A-12 fuselage and body are primarily constructed of 6061 aluminum alloy, which can withstand high corrosion and fatigue. 6061 makes up the fuselage and wings. 6061 also makes a name for itself as being low-cost. The standard use of 6061 allows costs to be reduced as well, and gives the airframe a longer mean time between skin maintenance, durability, all in a platform that can withstand the stress of high-G flight.

( http://asm.matweb.com/search/SpecificMater...assnum=MA6061t6 )

( http://www.aircraftspruce.com/catalog/mepages/aluminfo.php )

Smaller hardware and areas in need of high strength to weight ratios (particularly in the F/A-12 B) surpassing the 2024 alloy are constructed out of Aluminum Lithium Alloy 2091, which has a smaller composition of copper, mixed with Lithium, Zirconium, and Aluminum. This construction gives the airframe light weight, high performance potential, low maintenance, and low cost versus conventional construction materials.

2091 was selected for it's high tolerance to corrosion and fatigue, which were not present in other aluminum alloy structures, such as alloy 2024.

2091 properties

• Density: 2.58 g/cm3
• Melting range: 560-670 degrees celcius
• Elastic modulus: 75 GPa
• Specific heat (100 degrees C): 860 J/kg-k

(http://webcache.googleusercontent.com/search?q=cache:MKpIC50Z1v4J:www.metalwebnews.com/howto/alloys/alloys.pdf+aluminium-lithium&hl=en&gl=us&ct=clnk&cd=1

Page 3)


Powerplant
The turbofan selected was optimized for a higher thrust-to-weight ratio than the F-5 previous, giving the F-12 improved maneuverability capacity, while still being based upon the concepts of the original F-5's turbojet engine. The selected turbofan was a lightweight and military application of the concepts explored by the General Electric F414 turbofan, providing an advanced FADEC-controlled turbofan that used high pressure ratios to forward fuel performance and light weight. The turbofan provides a dry thrust of around 61-62 kN, and total wet thrust of 85 kN.

• Length: 355 cm
• Fan diameter: 89 cm
• Dry weight: 1,079 kg
• Compressor: 5-stage high pressure axial
• Turbine: 2-stage (1 low-pressure, 1 high-pressure)
• Pressure ratio: 30:1
• Specific fuel consumption:
  - Dry: .798 lb/hr/lbf
  - Wet: 1.64 lb/hr/lbf
• Bypass ratio: .47

The engine uses blated disks in it's high pressure combustor stages to minimize weight, similar to the design of the F414. However, unlike then F414, the engine of the F/A-12 incorporates these blated disks in all it's high-pressure compressor stages (of which there are five). The axial stages act to give the F/A-12's engine an moderately high pressure ratio for it's weight class. In addition, reliability and the ease of manufacturing parts helped reduce the costs of the engine.

The pressure ratio of 30:1 gives the F/A-12's engine more thrust for the weight of the engine, a better specific fuel consumption rate with it's mixture of systems (.798 compared to turbofans usually ranging above .8). These all factor in to key points in engine reliability, high thrust-to-weight ratios, and other factors in the design of the F/A-12 as an air superiority fighter, ensuring maximum performance in a manuever. The bypass ratio of .47 gives it higher fuel economy than the F414, and thereby the aircraft more performance from the same amount of fuel.

To reduce manufacturing costs, the blated disc fans and the other components were attached using the friction surfacing method of dissimilar materials welding.


Cockpit

The F-12 has a heads-up display showing an artificial horizon, airspeed in KIAS, and altitude in metros (or feet, depending on setting). Other digital displays powered by the avionics bus systems include a fuel situation readout, displaying the remaining amount of total fuel in kilograms, an EFIS display showing heading and other navigational markers, an ECAM system displaying engine and system conditions as well as providing active-time statistics, and a weapons display giving the ability to select, arm, and inventory remaining weapons and armaments.

Airspeed indicators and altimeters are shown along with vertical speed indicators, and other traditional dials in orthodox 'six-pack' configuration. Engine power, flap and speedbrake angle, and fuel/ignition lines are controlled via handles located to the left side of the cockpit.

The cockpit itself is designed in an elongated way, allowing the incorporation of advanced avionics systems while not compromising to any serious extent the weight of the aircraft, which is crucial in it's designation.

Avionics

The Northrop Grumman AN/ALR-67(V) Radar Warning Receiver allows for assessment and warning of oncoming threats, and controls the chaff and countermeasure systems onboard. The RWR system operates on the C and J frequencies (between .5 and 20 GHz) and offers advanced system coordination. The system costs around $1.5-$2 million after total procurement and incorporation into the F-12's frame.

The Emerson AN/APG-69, a modern holdover from the F-5 Tiger II upgraded systems, provides accurate control of both air-to-air and air-to-surface threats and the management of the systems of the F/A-12. The AN/APG-69 uses X band doppler radar to allow for limited weight while having a precise radar locator. Furthermore, the AN/APG-69 was designed to have advanced characteristics provided for light fighter craft, with a weight of 80 kg, a look-up range of 30 nm, a look-down range of 20 nm, and an MTBF of 200 hours.

Wings and flight controls

The F/A-12 has aileron and flap control on it's main wings, and incidence elevator control with the rear horizontal stabilizer. All wings are swept back at the same angle, along with all other angled surfaces on the craft. The triangular wing design back from the leading edge extension gives the F/A-12 it's signature maneuverability as a lightweight platform. The horizontal stabilizers were increased in area, and shaped to maximize the direction of airflow, increasing wing area and thereby maneuverability.

The naval variant has thicker wing roots and longer wings, allowing for the specific controls needed during CATOBAR arrest and recovery, as well as takeoff and approach.

Range and fuel

The F/A-12 has a total range of around 956 nautical miles, which is increased in the naval variant, and a ferry range upwards of 2,500 nautical miles, allowing the F/A-12 to be a large improvement in a long-range air superiority fighter when compared to the F-5 Freedom Fighter. The F/A-12 maintains competitive readiness in acceleration and in flight readiness, enhanced largely by it's ease of maintenance and flight preparation, a characteristic inherited from the application of the evolution of the F-5's design.

External fuel tanks improve range upwards of 1,000 nm, and ferry range at varying rates (dependent upon the amount of fuel).

Radar signature

The F/A-12, being primarily an air superiority dogfighter, was not designed with the deliberate reduction of radar signature in mind. However, it does incorporate certain characteristics which would act to slightly reduce it's cross section. All flight surfaces, including wings and inlets, deflect at the same angle. Without external arms, the F/A-12 maintains a noticeable but still an improvement in radar cross section when compared to earlier fighters.

Armament

The F/A-12 can carry up to 6 missiles, primarily the AIM-9. 2 missiles are mounted on the wingtips (not default configuration) while the other four are wing-mounted. In air-to-surface attack configuration, around 2 air-to-surface missiles followed by an assortment of dumb and laser-guided bombs with 2 air-to-air missiles and the same gun platform for defense.

The two underwing hardpoints farthest from the fuselage are equipped to handle external tanks, and a belly hardpoint intended for bombs is also outfitted to carry heavier tanks.

Each of the two .20 mm guns has a total of 300 rounds. The two guns are mounted closely together in the nose, and converge to an aimed target. The total capacity of 600 rounds are stored in easy-to-maintain gun compartments on the side of the nose, and are designed for g-resistance and overall reliability by the simplicity of the barrel design via 5

Cost

The F/A-12 A costs around $49.2 million to produce, at a weapons systems cost of $52.8 million. The F/A-12 B costs $51.2 million to produce, at a total systems cost of $53.1 million. Maintenance costs are reduced to near minimum, requiring only a 2 or 3 person crew for regular tool maintenance, given the low-maintenance single engine and the 'ease of maintenance' design inherited from the F-5.

A single larger engine would be cheaper, and can also be more powerful. Also, this might help your design some.

Tacking on to what Lamoni said, one engine over two is also going to be much better power-weight wise.

Also

Haven't seen anything to suggest Al-Li will be reduce maintenance nor be cheaper than conventional alloys.

http://webcache.googleusercontent.com/sear...us&ct=clnk&cd=1

This is where this was from.

If you're going to compare Al-Li to carbon fiber composites, be aware you're comparing one expensive alternative against an even more expensive alternative. CFRP's aren't what you'd call conventional; they aren't cutting edge but they are only just starting to feature in aircraft if you understand what I'm saying.

Al-Li might be more resistant to fractures than other materials but it doesn't eclipse other materials used in aerospace.

Perhaps pure aluminum, then?

Also, how well would the avionics suite work with the F-12? It seems the addition of any more equipment, such as the ALQ-144, would be out of the question.

Wasn't there a problem of the M39 leaking burnt powder into the avionics-compartment?

I wasn't using the M39.

No one really uses pure metals for structural purposes. Only very rarely.

I meant in relation to anything else.

What sort of [twin] 80 kg 20x102mm revolver-cannon(s) are you using, then?

Also, single-engined F-18E Super-Rhino.

Maybe a cross between the M39 and the M621 in 45 kg weight and 1.83 m in length with reduced width?


And F-18 wouldn't work.

1. The M39 has a higher rate of fire than the M621 (1,200 vs 800 rds/min)
2. All revolver-cannons, being revolvers, have gas-leakage

3. The F-5 went several developmental directions
a. One went straight for a single larger and more powerful engine, and strengthened structure at current size as the F-5G/F-20 for a dedicated-ish lightwieght-fighter.
b. Another re-optimized its airfoil with leading-edge-extensions as the YF-17 for a more multi-role purpose (which attracted Navy-attention since the YF-16 was gunning for the F-20's job)
-Which then was made larger as the F/A-18, and larger-still with the F-18E.

So, to employ the improvements from all into one gigantic package... Most epic multi-role ever... unless we did it in a fly-off against some imaginary Supersized F-16 or F-35...

So now I need to find a turbofan capable of 127 to 190 kN of dry thrust...

Well, I guess some avionics are about to get powdered.

I'd be more likely I'd keep the two engines and go the path of the YF-17. This isn't supposed to be multi-role, although any enhancements within the name of "light maneuverable ASF" are go.

And I wouldn't have a possible need of such a turbofan. I'm not building a $100 million super-fighter. I'm building a dependable, inexpensive yet modern fighter than can do it's job well and take maximum benefits from energy acceleration in a dogfight in it's performance.

Therefore, I shaped up the F-5 A a little differently, gave it a more powerful and more efficient engine (turbojet vs. turbofan), and re-did a good deal of the avionics.

I guess that's what I get when I try replacing a 13-ton F-4D Phantom II and 4-ton F-5E; with an 8 ton YF-17, with a 10 ton FA-18, with a 14-ton F-18E (empty wieghts).

F-35 weighs about the same class as the F-4D, so the fact that it can VTOL qualifies as a "flying-brick."

Meanwhile, the A-4, A-7, F-20, and F-16 wieghed about 5, 8.8, 5, and 8.5 tons respectively... So it CAN be done.

I'm not looking to replace something like the F-4, largely because the F-4 is a large distance from something such as this in role. I'm making a modern, maneuverable upgrade of the F-5 that has the potential to be navalized.

Still, the single F404 fanjet of the F-20 produces 70 kN of thrust dry wheras the twin 17 kN engines only make a collective 46 kN at full-afterburner.

Could also maybe perhaps cross-lock the twin-revolvers, Gast-style [like GSh-23-2] to pretty much eliminate jams.

And finally, GPU-5A (841 kg, 353 rds) or 9A4273 (480 kg, 150 rds) 30mm gun pods. Alternately, FFV ADEN (364 kg, 150 rds).

Also, I remember [urlhttp://www.quarry.nildram.co.uk/]DSI-intakes[/url] being remarkably simple/lightwieght for cruise-missiles, wondering if that could be employed upon this F-5 mod.

The F404 is too big for this platform.

How-so? Your specs list the FA-12 as longer (15.2 vs 14.4), wider (8.61 vs 8.53), and taller (4.66 vs 4.20) than the F-20 Tigershark [another mod of the F-5 that actualy did manage to fit the GE F404-100].

...

At this point, I'm going to direct you to Vaulty's F-5G mod.

A fair warning, a lot of the specs about F-5M are overly optimistic, don't try to work off them.
I do my design way more thoroughly now, though it did affect productivity somewhat.

http://img855.imageshack.us/img855/6748/f18evolution.jpg

This might be helpful. N-300 is a Tiger derivative. You might also want to look at the Northrop-Dornier work in the 80s, like the ND-102 or that design for Argentina I can't remember. ND-102 was supposed to be Mach 2+ with non-afterburning engines, but I can't remember what they were.

I think I just fell in love with the P610, since it'd fall-in nicely alongside the performance of the TF41 powered A-7E.

How about this? I could incorporate a single F404 engine, an extended leading edge, and keep essentially everything else roughly the same. Of course, maximum speed would increase and cost would decrease with the reduction of one engine and vamping up the other. It'd also improve maintenance.

Maximum speed wouldn't increase all that much, since fanjets are high-volume/lower-pressure motors than turbojets. Takeoff-run, rate of climb and ability to maintain airspeed throughout stiff manuvering would improve, though.

Oh, and maintnance would improve somewhat more if the F404 has parts commonality with your significantly larger airplanes.

A single engine can be made to be more powerful was my point. (Note the 'can')


I'm looking more for acceleration than max all-out speed.

Also check the F414 if you so choose, looks like it's a common engine bay size.

Re-write complete. Design incorporating some of the F414's design features:

Some of this stuff doesn't quite make sense

Higher pressure generally means higher, not lower, weight. I'm yet to see an engine, pump or pipe of any kind for which this isn't the case.

This particular engine shares no commonality with the F414 at all. The F414 is expected to deliver high subsonic performance at all levels, this engine is designed to deliver high subsonic performance at high altitudes only. The difference in temperature caused by compression between the less dense air at 20,000 feet + and the dense air at sea level is substantial. I really don't think you can have a 32:1 engine performing at Mach 1 at sea level, although I could be wrong.

I don't see how you figure that reliability will scale positively with increasing combustion pressures. If anything, it's going to be scaling the other way.

There are reasons that turbofan engines have a low pressure turbine and compressor in addition to the high pressure systems. I'm not an expert on turbines but I am reasonably sure you need to keep the low pressure component. No endorse might be able to clarify for us.

Duh.
The high pressure compressor is called that because it compresses the air from low pressure to high pressure, as opposed to the low pressure compressor that compresses the air from ambient pressure to low pressure.

So yeah, the statement makes no sense.

Which statement was that in the first place? The one about the two high pressure compressors generating higher pressures?

I've moved the pressure ratio down to 30:1. To be honest, I understood that pressure/bypass ratio related to thrust performance and efficiency to varying degrees.

Plus, the Pratt & Whitney F100 manages to maintain performance with a pressure ratio of 32:1 - http://en.wikipedia.org/wiki/Pratt_%26_Whi...8F100-PW-229.29

Okay, so, when we talk about high/low pressure compressors, we're really talking about the overall design of the engine.

The simplest jet engine has a single fan in the front and a single fan in the back, one driving the other. You can add additional stages, but they're all on a single shaft. This is called a "single spool" jet engine, and we don't make them anymore because they such balls and RPM matching compressor/turbine stages is a pain in the ass with a single spool.



Now, a great advancement was the twin-spool jet engine. In this case, there are two shafts: one nested inside the other. The front half of the compressor and the rear half of the turbine are hooked together, as are the rear half of the compressor and the front half of the turbine. The front part of the compressor compresses the air from ambient to some intermediate point, and the back half compresses the air from that intermediate point to whatever the whole compressor is rated to. Likewise, the front half of the turbine expands the air from whatever it comes out of the combustor at to some intermediate point, and the rear half of the turbine expands the air back out to ambient.

The "low presure" stage is the one that compresses from ambient to the intermediate compressor point, and expands from the intermediate turbine point to ambient. The "high pressure" stage compresses from the intermediate compressor point to the pressure the combustor needs, and then expands that air from the combustor point to the intermediate turbine point. Therefore, an engine can't have two high-pressure compressor stages with no low pressure compressor. The "high" or "low" has nothing to do with the pressure ratio of the stage, it refers to the working pressure within the stage.

A twin-spool design lets you do a few things. First of all, it increases engine stability and improves performance at different mach numbers. (it makes dealing with variable bypass and inlet starting a HELL of a lot easier too) It also does nice things for compressor-turbine matching, and it helps with stage-matching within the compressor and within the turbine.



Those of you following along at home will note that Rolls Royce has pioneered a three-spool jet turbine, giving it low pressure, intermediate pressure, and high pressure spools. This does really cool things to the engine, but designing it can be complicated. I think the French had one in a fighter once.

Pratt and Whitney are working on what they call a Geared Turbofan, which lets you maintain the simplicity of a twin-spool design while running the fan (and maybe the first compressor stage, I'm not sure if it's included as well) at a lower RPM via gear reduction. This prevents supersonic losses and lets you turn a MASSIVE fan with MASSIVE bypass ratios, but is possibly unsuited for fighter aircraft. Efficiency gains have to overcome gear losses, so low bypass "leaky turbojets" won't benefit from this.

Alright, it seems I misunderstood the design of the CFE engine. Not that it's relevant to a military turbofan to any great extent. Thank you very much for the explanation.


All this engine would need would be reliability, simplicity, capacity to be low-cost, and have as much potential in energy acceleration as possible. When comparing the F404 and the F414 for this design, along with a few of Pratt and Whitney's selections, it seemed the F414 was the winner. For originality's sake, I reduced the overall thrust, introduced bladed fans (blisks) on all the 5 stages (down from 7 etc. in the F400 series).