NationStates Jolt Archive

INTRODUCTION
As many have seen before in several threads I’ve made, I have a knack for digging up information, and I like to share it. I’ve done tanks and ships, and aircraft are just a natural addition to the fold. Now, this is quite a bit of a work in progress (like several of the other ones), but I figured I might as well post the huge amount I already have. Of course I’ve only touched on some things, and some others will be coming soon (look for price and operating costs, as well as avionics, missiles, radars, etc). Hopefully I’ll have the time and resources to make this as complete as some of the other ones I’ve done.
Also look for the Nuclear Weapons and Small Arms threads, which I’ll hopefully have up within a month or two.



Engines
One of the most important, and misunderstood, aspects of aircraft are the engines. Few players understand the different types of engines, and even fewer know their strengths and limitations, so I will be providing a brief description on those. However, first we’ll look at some general aspects of engines and speed.
For starters, all engines produce thrust, which is what moves the aircraft forward. This is measured as a weight. For example, an F-100-PW-229 turbofan can generate 29,000 lbs (13,152 kg) of thrust on full afterburner. The comparative amount of thrust compared to the weight of the aircraft (thrust/weight ratio) is one of the major factors in determining aircraft speed. Most combat aircraft will opt for a high ratio, which will give them greater speed and climbing capabilities. When the thrust produced exceeds the weight of the aircraft, as it can in ones like the F-15 and F-16, the aircraft can perform some impressive feats, such as accelerating straight up.
It should be noted that things like speed and range are quite relative, and these can change dramatically based on load and altitude of the aircraft. For example, while an unloaded F-15E could pull up to Mach 2.5 (2660 km/h) when flying at about 35,000 ft. However, the same aircraft will be limited to Mach .74 (908 km/h) when fully loaded and flying at low altitude. The combination of practical limitations, increased air resistance, and increased drag from the weapons will all serve to greatly reduce its efficiency. The same goes for range. The aircraft will perform better at certain altitudes and speeds, and loading external fuel tanks instead of ordnance will help increase range.
Now, as for engines, there are a few things to note. One important one is that all engines mix air with fuel, which is ignited to either propel the aircraft forward through the exhaust or drive a propeller or rotor shaft. With the exception of rocket engines, which carry their own oxidizer (air substitute) with the fuel, current engines rely on compressed air taken from outside. As a rule, the greater the compression (pressure), the more thrust an engine will be able to develop. Therefore, most improvements in engine design are either to increase compression, of allow for increased compression, as this is the single most important factor.
Another thing that can be used to increase thrust is an afterburner. This system, which is present on most fighter and many bomber aircraft, allows for raw fuel to be dumped into the final combustion chamber, where it mixes with the exhaust and ignites, further increasing thrust, though it will consume fuel at a phenomenally higher rate.
Now, these are just some general things that apply to most engines. There are many different types of engines, and they can be quite different in both performance and operation. In here, I’ll look briefly at the engine types that are likely to be seen today, and I’ll try to steer clear of being to technical.

ROCKET ENGINES have only been used on one combat aircraft, the Me-163B Komet from WWII. Though such engines provide exceptional speed and are very popular with missiles, they have a major drawback, and that is that they consume fuel at a phenomenal rate. The Me-163B had enough fuel for only about 4 ½ minutes of powered flight, with the rest of the flight being gliding. Similarly, the vaunted X-15 only carried enough fuel for 80-120 seconds of powered flight, which amounted to only 1/5 of the total flight time. Most rocket powered aircraft were experimental units, notably the Bell X-1 (world’s first supersonic flight), and the X-15 (highest altitude and fastest aircraft – 354,200 ft & Mach 6.7). The greatest advantage of rocket engines is that, unlike jets, they require no airflow to operate. This makes them ideal for use on spacecraft and supercavitating systems. The high speed also makes the excellent for short-range missiles. However, on the reciprocal, rocket fuels require their own oxidizers, unlike jet engines, which use the air for that. This means that they require a greater volume of fuel to operate.

CENTRIFUGAL FLOW TURBOJETS were the first jet engines. They powered WWII aircraft like the Me-262 and Meteor, and later the F-80, F-86, and MiG-15 from the Korean War. These used a pump-like impeller to compress the incoming air flow, which limited the pressure ratio (the defining characteristic in engine performance), provides significantly reduced thrust. As one might note, none of the aircraft that used them could break the sound barrier. These are cheaper engines due to the lower heat and greater simplicity, but are not as fuel efficient as turbofans.

AXIAL FLOW TURBOJETS appeared in the mid 1950s on aircraft like the F-100 and MiG-19, which were the first supersonic combat aircraft. These are very similar to centrifugal flow turbojets, but contain a series of axial compressors that increase the pressure of the air. Kicking in the afterburner in these engines allowed brief supersonic dashes by providing an increase in thrust of up to 50%, but this consumes fuel at 3-4 times the normal rate. This engine design stayed with new aircraft designs into the 1960s, and some aircraft that used it, such as the F-4 Phantom II, still serve in modern militaries today. As with centrifugal flow turbojets, these lack the fuel efficiency of turbofans.

HIGH-BYPASS TURBOFANS appeared in the 1960s. They differ from turbojets in that they only push part of the air flow into the main compressor, with the rest of the air being diverted into a bypass duct and remaining unused. Now, this helps because the amount of air being used, more work can be done on a smaller volume of air, providing increased pressure ratio, and this was combined with a faster spinning compressor to further increase the advantage. In most high-bypass turbofans, 40-60% of the airflow is vented away, with some designs reaching as high as 95%! These engines provide advantage in a combination of high speed and a fuel efficiency that’s almost as good as turboprops. However, the problems that arise make them quite expensive. But despite higher cost, the advantages could not be ignored, and turbofans have been the engine of choice for all combat aircraft since the 1970s. Turbofans provide a massive increase in top speed, with full afterburner increasing speed by up to 65% instead of the 50% in the turbojet. However, this is countered by the fact that the afterburner consumes fuel at a 25% greater rate than that on a turbojet, but even without afterburners, turbofans can produce more thrust than many turbojets can even on full burner, allowing larger aircraft to be built while still maintaining high subsonic cruising speeds. Turbofans are also quieter than turbojets. The only real weakness of a turbofan, aside from cost, is the fact that it is still optimized for subsonic speeds. This means that supersonic flight, while it can be achieved for longer periods than in turbojets, still requires an afterburner.

LOW-BYPASS TURBOFANS are among the newest engines entering common military service. These work in a similar manner to the high-bypass turbofans, but only vent 15-20% of the air into the bypass duct, making them much more like turbojets. This allows for the supersonic cruising speeds of modern aircraft, but at a cost of top speed, as the greater volume of air, which is more like that of a turbojet, knocks down the boost provided from afterburning.

TURBOPROPS are similar to turbofans in concept, but use a turbine to drive an external propeller for thrust. In general, the jet portion only provides about 15% of the engine’s thrust, with the propeller doing the rest.. The primary advantage of these engines is the greatest fuel efficiency of any engine type, providing exceptional range and endurance. They’re also somewhat less susceptible to low-level hazards like birds, which can disable jet engines if they’re sucked into the intakes. Finally, they have the benefit of lower operating temperatures than jet engines, making them much easier and cheaper to make and maintain. On the downside, they are the slowest modern engine type, with even high subsonic speeds being quite unlikely with them. They are also known to provide a rough ride due to vibration, which means turboprop aircraft are much less comfortable for passengers than jet-propelled ones. Finally, their placement is more restricted (wings only) than jet engines. The only major turboprop equipped combat aircraft in service is the Soviet Tu-95 (equivalent to B-52). However, they are very common on transports and patrol aircraft such as the C-130 and P-3.

RAMJETS are a further development of turbojets, with the idea being to eliminat all the moving parts and allow the motion of the engine itself to compress air. These provide phenomenal speed (Mach 2 to Mach 5), rivaling that of rockets. At very high speeds (Mach 3+), these are extremely efficient engines, beating out turbofans and even turboprops for fuel economy. The lack of moving parts also makes them rather cheap, though the extremely high operating temperatures (and thus necessary materials) help to counter that. The greatest problem is that, since these require the engine to be moving at a decent speed (about Mach .4) before they can even be used, they have not been popular in anything but missiles. After all, a second engine or a booster would be required just to get the ramjet working.
The biggest problem with ramjets is that they cause shockwaves in order to slow the air to subsonic speeds as it passes through the intake. While this helps fuel efficiency, at hypersonic speeds (Mach 5 and up), this causes enough disruption of the airflow to seriously hinder the efficiency of the engine, and thus ramjets are ineffective for Mach 5+ flight. Hence, these engines are only really good for speeds in the range of Mach 3 to Mach 5. Any slower, and a turbofan would be better, and any faster, and you need a Scramjet.

SCRAMJETS (Supersonic Combustion RAMJETs) are another type of ramjet, and provide the greatest speed of any engine available. These engines require extremely high speeds to initiate (about Mach 2), and have even higher operating temperatures, both for the engine and the aircraft it propels. However, by refraining from slowing down the airflow inside the engine, these provide efficient Mach 5+ operation, and can push aircraft even beyond Mach 10. Naturally working with the heat required for these and anything that uses them has been prohibitive, and that alone has caused great trouble with them. Once that hurdle is dealt with, there’s also the problem of getting an aircraft or missile up the required speed without taking up too much weight and/or space for boosters or other engines.



Stealth
Contrary to what is still popular belief, stealth aircraft are not invisible. Rather, they use several techniques to reduce their signature to the point that they are difficult to detect. Another myth is that they will always have this tiny signature. Even the B-2 can be detected by your average search radar if it gets close enough. However, such radars can’t detect it until it gets within a few dozen kilometers, so it can fly around the detection zone without having to go through it like most other aircraft.
There are two main kinds of sensors against aircraft (Radar & IR), and several methods of reducing the signature of each.
For starters, there’s radar. Radar systems work by focusing a beam of electromagnetic energy and detecting any that is reflected back to them. The amount of energy reflected back by a target is called the Radar Cross Section (RCS), and indicates how well and how large an object will appear on a radar screen. RCS is measured as an area, and the stealthier something is, the lower its RCS is in proportion to its actual size. Thus, the best way to defeat radar is to reduce the RCS, which means that the signal that is returned to the receiver needs to be reduced as much as possible. There are two primary ways to do this: shaping and RAM. Both of these have can trace their origins as far back as WWII, particularly Germany.
RAM stands for Radar Absorbent Materials, and are composites that absorb more of the signal than normal materials, leaving less to reflect back. Usually, these materials are not very strong, and are thus applied as coatings over more traditional metals. The earliest ones date back to the 1940s, and by 1943, Germany had two kinds of RAM coatings, known as Jaumann and Wesch, which were applied to the snorkel masts of their U-Boats, and reduced the detection range of these masts from 8 miles (12.8 km) to 1 mile (1.6 km). However, these were still difficult to maintain, and didn’t adhere well to the masts when immersed in seawater for extended periods of time. Modern RAM coatings are a little more reliable (though the maintenance problem persists to this day), and can absorb up to 90-95% of the radar energy that strikes them. These are used in several ways: One of the most common is as an appliqué material for combat aircraft, which can be applied to reduce radar cross section, with one of the most notable ones being the radar absorbing paint (Iron Ball) that the US supposedly uses. When applied to non-stealth designs like the F-15 and F-16, these coatings can reduce RCS by as much as 70-80%. The other common method is to use Radar Absorbing Structures (RAS), which consist of a rigid, hollow structure made strong, radar transparent (ie the energy passes through them rather than being reflected) composites that are filled with RAM. The best designed of these can absorb up to 99.9% of the radar beam’s energy.
Shaping, unlike RAM, must be built into the aircraft design. However, it’s far more effective at reducing RCS when used properly. Shaping works by changing the directivity (how much energy travels back toward the receiver). Specifically, the radar beam is most efficient when it strikes the target at a perpendicular (90 degree) angle, and the further from perpendicular the target surface is, the less energy is reflected back to the receiver, with the rest being deflected away from it. Now, this can be a very effective method of reducing RCS. A simple tilt of 10 degrees from perpendicular will result in about 97% of the energy being deflected away, and going further to 30 degrees will take this up to 99.9%. Now, there are actually several different kinds of shaping. The F-117A, for example, uses numerous faceted surfaces (think a gem or disco ball) to direct the radar energy away. The B-2 on the other hand, uses a technique called platform shaping, which gives it a smoother look, but has the same basic effect. Another important part of shaping is the basic airframe design. Simply put, the sharp breaks between the wings and fuselage and the tail surfaces of most aircraft greatly increase RCS. The solution, as seen in the F-117A and, even more notably, the B-2A, is to eliminate these altogether with a flying wing design. Now, the advantages of this design were known even in WWII, and both the US and Germany had prototypes for such aircraft. However, both ran into one major problem: the flying wing, like the forward swept wing on the X-29 and Su-47, is extremely unstable, and it wasn’t until appropriate computer systems could be developed that this design became viable. Now, however, you cannot make a truly stealth aircraft without it, though there is one other notable drawback, and that’s the fact that flying wings are very slow designs. Due to air resistance and structural limitations, these are solidly subsonic aircraft.
There are also some notable myths regarding stealth that need to be addressed. The first and most significant of these is that stealth reduces the range at which an aircraft or projectile can be detected by radar, but does not make it undetectable. The closer an aircraft gets to a radar, the less effective the stealth features will be. Most notably, the shaping that is the most popular technique will lose effectiveness as a greater portion of the energy will be reflected close enough to be gathered by the receiver. Now, though specific ranges have been given, the detection range rather relative, while a radar that can detect a B-52 from 366 km must be within 36.6 km to detect a B-2, another more powerful one might be able to see a B-2 100 km out, and a weaker one might need to be within 3 kilometers to see anything. In the end, the advantage of a stealth bomber is not so much to fly through radar defenses, but to create holes in a network’s coverage so the aircraft can fly around them.
The other method of detecting aircraft is infrared (IR), which is used to detect the heat given off for the aircraft. Now, IR is nowhere near as effective as radar for a long-range detection system, as current ones have very limited range, especially compared to radar. However, as a short-range detection system, it’s become very popular, due mainly to the fact that IR detection systems cannot be detected by passive sensors. IR is also popular in smaller missiles, as IR seekers are simpler and don’t require as much space as radar ones. Now, there are two important types, or windows, of IR that can be used to detect an aircraft, based on wavelength. Mid-IR, which includes the heat given off by the engine parts and exhaust, is used by many IR guided missiles. Long-IR, which is what’s caused by the sun heating surfaces and the friction caused by moving through the air, and is used by several more modern missiles, as it allows for engagement at any angle. Modern detection systems, including FLIR (Forward-Looking InfraRed) and IRST (InfraRed Search and Track) systems used by aircraft can search for targets in both windows, providing a dangerous short-range detection system. Because of this, true stealth aircraft need to be difficult to detect by IR as well. Part of this (Mid-IR) can be helped by eliminating the afterburner, which causes a good deal of heat. In addition, one must take steps to cool the engine exhaust, which usually entails designing the inlet so that cool ambient air will mix with the hot exhaust gases, dropping their temperature. Though this is not going to be a phenomenal drop, it’s enough to greatly reduce the signature. This in turn must be combined with measures of dissipating exhaust such as the long-thin nozzles used in the B-2 and F-117 (which incidentally also block the view of the hotter portions of the engine). Long-IR, on the other hand, can’t be helped very much, but using certain composite materials with good IR dissipation qualities will help, as well as the obvious trick of flying at slower speeds and at night. With this in effect, the detection range for IR sensors is about that of radar ones. Of course, this means that the effectiveness of suppression measures against IR are quite limited, and further developments there could prove devastating to stealth aircraft.
Another notable myth is that you can make superfast stealth bombers. This is only partly true, as the same designs that allow aircraft to achieve, maintain, and operate at extremely high speeds will also have a larger RCS. In the leap to make the B-1, for example, a supersonic aircraft, it had to be designed with 10 times the RCS of the B-2. Granted, this is still a vast improvement over the older B-2, but as the aircraft get faster, this becomes even more pronounced, as many popular stealth features (particularly several forms of shaping) are not very aerodynamic. Sorry people, but this means that there aren’t going to be any Mach 3 bombers with the RCS of the B-2. Now this isn’t to say they can’t be stealthy, but they will not be anywhere near as stealthy as the B-2, F-117, or even the F-22. This comes from the fact that they’re generally limited to a degree of shaping backed up by RAM and RAS, however, RAM can’t be used much (it’ll peel off), and some areas will need greater strength than RAS can provide, thus bumping up RCS. And naturally, any engine that pushes aircraft past Mach 3 is going to show up like the 4th of July on IR, no matter what suppression features you add to it.
The final key to stealth is EMCON (EMission CONtrol). Specifically, many signals that aircraft send out, particularly radar and radio, can be intercepted by passive sensors, which can then use them to figure the location of the aircraft. For this reason, stealth aircraft do not use radars, and reserve radios for emergency use only. Laser targeting systems can also be dangerous, as passive sensors can detect them as well. The ideal detection, tracking, and engagement systems for a stealth aircraft are IIR (Imagine InfraRed) and EO (Electro-Optical). Both of these are passive, and thus cannot be detected. Both of these act like cameras, using either visible or infrared light to create a picture, which a weapon system can then be locked onto. Though short-ranged, they are the best ways of detecting and engaging a target without being discovered in the process.


Speed Glossary
Hypersonic: Refers to anything exceeding 5 times the speed of sound. This is faster than a mile a second at sea level.
Mach Number: The speed of an aircraft/projectile relative to the speed of sound. This is portrayed as a decimal with Mach 1 being the speed of sound, Mach 2 being twice the speed of sound, Mach 2.5 being two and a half times the speed of sound, etc.
Mach 1: The speed of sound. It changes based on air density (ie different altitudes). Mach 1 at sea level is about 1226 km/h (762 mph), while Mach 1 at normal cruising altitudes (35,000 ft / 10,500m) is 1063 km/h (661 mph).
Subsonic: Refers to anything that is flying slower than the speed of sound.
Supersonic: Anything exceeding the speed of sound. Generally considered Mach 1 - Mach 5.
Transonic: Anything flying at a speed of Mach .9 to Mach 1.4



Maneuverability
This is an area that’s really hard to quantify, though many have tried. One popular measure is by the load factor (the G forces the aircraft can stand up to), however, as will be shown later, this really doesn’t leave much of a gap. So, the real test of maneuverability comes in other aspects. These include speed, rate of climb, rate of turn, turn radius, and special techniques. Speed and rate of climb, as one might expect, are really measures of engine performance, and not much can be done to the aircraft without them. Rate of turn (how fast it turns) and turning radius (how much space it needs to make a turn), on the other hand, are affected by the maneuvering surfaces of an aircraft. There are a number of control surfaces that an aircraft can have, including rudders, flaps, leading edges, and canards, all of which are moving control surfaces that help to increase agility. In addition, there is the factor of thrust vectoring, which uses flexible exhaust nozzles to direct the thrust from the engines in different directions. Now this usually isn’t a great change, but even a small one can dramatically enhance the handling characteristics of an aircraft, or alternately eliminate the need for other control surfaces. There are two general types of thrust vectoring. The simplest is 2-D, in which the engines of an aircraft can direct the exhaust up or down to assist in maneuvers, or more importantly, to allow for slower takeoff and landing speeds. 2-D thrust vectoring can be found on the F-22 and most VTOL aircraft. 3-D thrust vectoring, as found on the Su-47, on the other hand, allows for the exhaust to be directed from side to side as well, providing even further increased performance. One of the most notable advantages of thrust vectoring is the fact that it can eliminate the need for other moving control surfaces, which have a tendency to increase RCS. Thus, vectored-thrust aircraft can be stealthier.



G FORCES
G Forces are a measure of the physical stresses placed on pilots and aircraft during flight, as compared to the force of gravity on earth. Positive Gs are caused by an aircraft accelerating or pitching upward, and drive blood into the extremities. At +4.5-7g, a normal human can be expected to lose consciousness (G-LOC). Blackout (loss of vision) occurrs at 3.9-5.5g, and grayout (partial vision loss) at 3.4-4.8g. Modern G suits can allow pilots to remain conscious at up to +11g, though with the average suit, blackout can be expected at 9g.
Negative Gs are caused by an aircraft decelerating or pitching downward, and drive blood into the head, and the loss of vision for this is known as redout. -2g will cause redout in an unprotected human, and a good G suit will up this to –4.5g.
It should be noted that G Forces are caused by maneuvering and by changes in speed. If speed is constant, there is minimal additional force.
G forces were found to be a problem as early as the 1940s, when pilots were known to occasionally black out in high performance aircraft like the P-51 and Fw-190 while maneuvering. As aircraft became faster, it became necessary to provide measures to counter the G forces. The suits that were developed for this, known as Anti-G Suits (but commonly referred to as just G Suits), used tight straps to restrict the flow of blood in key areas, helping to decrease the effect that excessive Gs had on blood flow. However, even with current G suits, blackout occurs immediately at about +8-9g and redout at -4-4.5g. Because of this, no current aircraft is rated at greater than +9G / -4.5G, as no pilot can be expected to take it.
The same cannot be said of unmanned aircraft and missiles, however, and 60+ Gs is not unheard of for SAMs. Even current aircraft usually have the structural strength to maintain 15 Gs. It’s just that the pilots don’t, preventing them from pulling that much. However, this number can drop considerably when an aircraft is carrying external ordnance.

Below is a list of a number of aircraft and their rated load factor (maximum Gs):

COMBAT AIRCRAFT
AMX: +7.3G / -3G
AV-8B: +8G / -3G
EFA 2000: +9G / -3G
F-2A: +9G / -3G
F-14: +6.5G
F-15E: +9G
F-16: +9G
F/A-18: +7.5G
F-35A: +9G
F-35B: +7G*
F-35C: +7.5G*
F-117A: +6G
FC-1 (AKA Super 7): +8G
Harrier: +7G
JAS-39 Gripen: +9G / -3G
MiG-29: +9G / -2.5G
Rafale: +9G / -3.2G
S-37 Berkut: +9G
Sea Harrier: +7.8G / -4.2G
Tornado: +7.5G

TRAINERS/LIGHT ATTACK AIRCRAFT
ADA LCA: +9G / -3.5G
ALX: +7G / -3.5G (+4G / -2.2G w/ external stores)**
BAE Hawk: +8G / -4G, (+6G / -3G with full payload)
EADS Mako: +9G / -3G
HJT-36: +8G / -3G
JL-9 (aka FTC-2000): +8G
JL-15: +8G / -3G
KT-1: +7G / -3.5G (+4.5G / -2.3G w/ external stores)**
L 39ZA: +8G / -4G
L 59: +8G / -4G
L 139: +8G / -4G
L 159A: +8G / -4G
M-346: +8 / -3G
MB-339FD: +7.33G / -4G
MiG-AT: +8G / -2G
PC-7: +6G / -3G light (+4.5G / -2.25G at max take-off)**
PC-9: +7.5G / -3.5G light (+4.5G / -2.25G at max take-off)**
PC-21: +8G / -4G**
T-6A: +7G / -3.5G
T-45C: +7.3G / -3G
T-50 (aka A-50): +8 / -3G***
Yak-130: +8G / -3G

EXPERIMENTAL AIRCRAFT
X-31A: +9G / -4G

TRANSPORT AIRCRAFT
C-295: +2.53G (+2.25 in overloaded conditions)

HELICOPTERS
A-129 Mangusta: +3.5G / -0.5G
AH-1Z Super Cobra: +2.6G / -0.5G
AH-64D Longow Apache: +3.5G / -0.5G
EH-101 Merlin: +3G
RAH-66A Comanche: +3.5G / -1G
CSH-2 Rooivalk: +2.6G / -0.5G
UH-1Y Iroquois: +2.5G / -0.5G
V-22 Osprey: +4G / -1G




A $1 million dollar fighter?
This is a concept that’s been given a few times, and is one of the more annoying ones. So, just for fun, lets take a look at what such an aircraft would look like:

1. Stealth. This would be pretty much nonexistent. Why? Well, as said, stealth comes from one of two things. The first is RAM (Radar Absorbant Materials), and the second is from shaping. Well. RAM is expensive, as well as rather maintenance intensive, so that’s out. Similarly, the unconventional designs that mark stealthy aircraft are inherently unstable. That is to say that a human pilot can’t fly them without a great degree of assistance. Naturally, this comes in the form of expensive computers, which cost more than our $1 million limit.

2. Radar. Unless we’re looking at vintage Korea or WWII systems, this’ll cost more than our limit, so you can forget about it.

3. Engines. These need to be simple and can’t use expensive materials like titanium. Most likely turboprops or turbojets. A little over Mach 1 is possible, but subsonic is much more likely, as it would be better in terms of cost and maintenance.

4. Armament: Against aircraft, only guns and maybe short-range IR guided AAMs like the Sidewinder could be used. Naturally, radar guided missiles would not be workable. For air to ground, it can carry unguided bombs and rockets. It can also deliver laser guided ordnance, but it won’t have the designator!

5. Communications: Simple radio, and things like landing lights, maneuvers and hand signals could be used to help send messages as well.

6. Fire control: Simple sights, with maybe a lock-on signal for AAMs.

7. Construction: You can forget titanium and advanced composites. Work with simple steel and aluminum.

And here’s your product (http://www.wpafb.af.mil/museum/air_power/ap40.htm)

That’s right. Even the MiG-21 or F-100 would cost several million today, as do many 1950s and pretty much all 1960s or later aircraft. Look to the Korean War or WWII for your $1 million fighter. Anything much more modern isn’t going to work.






*This is for the Boeing proposals. The Lockheed aircraft may be different, but it’s more likely that the load factors will be very close, if not identical to these.
**These are actually turboprop trainers rather than jet aircraft.
***A-50 is the designation for the combat version, which is a light attack aircraft. T-50 is for the training version.

Wow. Another excellent piece of work as expected, CSJ. And very useful for aircraft designers. Thanks!

But a question:

Does internal weapons bay generally increase speed (lower drag) and maneuveribility over a same aircraft with weapons and others mounted on only external hardpoints? It seems me that since it has been known that a load of bombs and large fuel tanks reduces maneuveribility on a "normal" aircraft (F/A-18s, F-15Es, whatever), wouldn't putting them into weapons bay save a lot of speed and maneuveribility, therefore may even allow them to maneuver well in an emergency situation?

So yeah this should be a sticky. Good work!

Good job! :)
However, both ran into one major problem: the flying wing, like the forward swept wing on the X-29 and Su-47, is extremely unstable, and it wasn?t until appropriate computer systems could be developed that this design became viable.The Germans managed to make a flying wing that could be temporarily made stable enough for gun use, and they also flew a forward-swept wing bomber prototype (the Ju 287), which they only abandoned because they needed fighters more urgently. WWII Germany also had the idea of building aircraft from stealth materials (Horten HoIX).
lying wings are very slow designsSo the Lippisch Supersonic Flying Wing wouldn't have worked? :(
Now, IR is nowhere near as effective as radar for a long-range detection system, as current ones have very limited range, especially compared to radar.Fifty miles is longer than the range of the AMRAAM...
The final key to stealth is EMCON (EMission CONtrol).There's at least one more way to detect a stealth aircraft -- turbulence.
Because of this, no current aircraft is rated at greater than +9G / -4.5G, as no pilot can be expected to take it.The Su-26 is a (not quite current) +12G/-10G aircraft.
This is a concept that?s been given a few times, and is one of the more annoying ones.Yet it's a real one. See the F-7MG.
StealthWood=Stealth! :D
2. Radar. Unless we?re looking at vintage Korea or WWII systems, this?ll cost more than our limit, so you can forget about it.Or take it from your recent spoils of war or possibly an AAM.
Naturally, radar guided missiles would not be workable.And why not?

I think having the pilot lie down also reduces Gs.

The Germans managed to make a flying wing that could be temporarily made stable enough for gun use, and they also flew a forward-swept wing bomber prototype (the Ju 287), which they only abandoned because they needed fighters more urgently. WWII Germany also had the idea of building aircraft from stealth materials (Horten HoIX).
I guess I should rephrase that a bit. Early designs could not be made both stable and that stealthy. The same features that were applied to make early flying wings stable enough increased RCS considerably, and they still suffered from control issues (which haven't entirely been solved btw. The F-117 is notorious for its handling characteristics). When I said flying wing, I meant the tailless one.

So the Lippisch Supersonic Flying Wing wouldn't have worked? :( It would likely have worked, but only as a test aircraft. Understand that the Lippisch flying wing was closer to a delta-winged fighter with a shrunken fuselage than to other flying wing designs. It also wouldn't have been that stealthy.
Most flying wings give decent subsonic handling, and could go up to transonic speeds, but not much higher due to increased drag.

Fifty miles is longer than the range of the AMRAAM...
AMRAAM (Advanced Medium-Range Air-to-Air Missile).
An excellent IR detection system could detect an afterburning aircraft at up to 85 kilometers, however, that range drops by 20-30% against a target that isn't using its afterburner, and most aircraft mounted systems have a range of no more than 30-35 km against cruising aircraft. An AMRAAM can go out to 73 km against a closing target at cruising altitude. At higher altitudes, it can probably about match that 85 km IRST. A good radar system can do several hundred kilometers. The 85 km IRST can detect an aircraft like the B-2 at maybe two or three dozen kilometers, the same as a radar that can detect a B-52 at 250-350 km, so IRSTs aren't as degraded as radars.

There's at least one more way to detect a stealth aircraft -- turbulence.Turbulence is both something that cannot be helped and, at present, has limited effectiveness as a detection system. Also, turbulence is detected by dopplar radar, so it would be considered indirect radar detection.

The Su-26 is a (not quite current) +12G/-10G aircraft.As you said, it isn't current.
The aircraft may be officially rated at that, but its actual load factor will be no different than any other high-performance aircraft with the same G-suit. There are new suits in the works that can allow people to sustain those Gs, but they're also not in service.

Yet it's a real one. See the F-7MG.Well, it appears I've missed that. However, the design criteria still holds for the most part, as that aircraft is of Chinese origin, which means that if anyone with a decent economy were to build the same aircraft, it would cost several times as much. But that's an issue for economics. Chinese and Soviet sales are also often heavily discounted, with them being used to pay for purchases and repay defecits. This can make them rather unreliable as a source for actual costs.
I'd also be interested in seeing how much they cost if constructed from the ground up, without using parts that are already in inventory.

Wood=Stealth! :D .
Wood=virtually useless in almost anything beyond WWII.
It's like the fabled plastic pistol, which, though made from mostly composite materials, still has quite a bit of metal in it, and it will still set off metal detectors (despite what the movies say). Wood cannot be used as the primary material because of its flammability and low strength. That means that there will still be a lot of metal in any modern airframe, and even if you put as much wood as you could, you'd lose more in performance than you'd gain from stealth.
The only effective modern use would be a plywood and stressed-skin transport for deploying special forces, such as the An-2 used by North Korea.

Or take it from your recent spoils of war or possibly an AAM. As spoils of war, you have to place very specific limitations on the number available, and that number will almost certainly be rather low. Not an appropriate solution. You can dust off old unused systems and sell them cheap, but you still have to admit they're old.
An AAM seeker is generally rather short ranged, maybe 20 kilometers. It will also need a significant amount of additional electronics to be suitable as a search platform.

Naturally, radar guided missiles would not be workable.And why not?
Okay, you could use them, but active ones would be limited to the range of the seeker (10-20 km), and semi-active ones would have to be older and similarly short-ranged designs. Remember, those cheap chinese fighters have very short-ranged radars. In the end, you'd be better off with IR.

I think having the pilot lie down also reduces Gs.It does to an extent, but the problem has always been having a pilot lie down and effectively maneuver an aircraft. Once you get past a certain point, it actually becomes less efficient because it interferes with the pilot's ability to control the plane, as well as look around.

[tag for brilliance...]

I guess I should rephrase that a bit. Early designs could not be made both stable and that stealthy.Okay.
It would likely have worked, but only as a test aircraft. Understand that the Lippisch flying wing was closer to a delta-winged fighter with a shrunken fuselage than to other flying wing designs. It also wouldn't have been that stealthy.Could one build a stealthy supersonic flying wing fighter with modern technology?
Turbulence is both something that cannot be helpedWhat about making it more aerodynamic?
Wood cannot be used as the primary material because of its flammability and low strength.I think I read about an aircraft that used some sort of material made of wood shavings (sawdust? little chunks of wood?) and glue that was so strong it didn't need an interior structure (it was a WWII aircraft, but still useful for aircraft that will be low-speed anyway).
As spoils of war, you have to place very specific limitations on the number available, and that number will almost certainly be rather low. Not an appropriate solution.Yea, but when you capture whole fleets or airports, you have a few more.
An AAM seeker is generally rather short ranged, maybe 20 kilometers. It will also need a significant amount of additional electronics to be suitable as a search platform.Indeed, not very good.
Okay, you could use them, but active ones would be limited to the range of the seeker (10-20 km), and semi-active ones would have to be older and similarly short-ranged designs.Right.
In the end, you'd be better off with IR.Indeed.
It does to an extent, but the problem has always been having a pilot lie down and effectively maneuver an aircraft. Once you get past a certain point, it actually becomes less efficient because it interferes with the pilot's ability to control the plane, as well as look around.
Right.

Turbulence is both something that cannot be helpedWhat about making it more aerodynamic?
Still won't solve the problem. The aircraft will still produce vortices and such, and the propulsion (i.e. the moving of air) by its very nature produces turbulence.
Also the amount of seperation and turbulent flow will vary with angle of attack.
With modern technology you can make wings very smooth, reducing skin friction and the turbulence it causes to very minimals, but there are still problems. Foreign particles, bugs, even water droplets, that collide with your wing will essentially change the shape of the airfoil, and therefore the flow.

INTRODUCTION
As many have seen before in several threads I’ve made, I have a knack for digging up information, and I like to share it. I’ve done tanks and ships, and aircraft are just a natural addition to the fold. Now, this is quite a bit of a work in progress (like several of the other ones), but I figured I might as well post the huge amount I already have. Of course I’ve only touched on some things, and some others will be coming soon (look for price and operating costs, as well as avionics, missiles, radars, etc). Hopefully I’ll have the time and resources to make this as complete as some of the other ones I’ve done.
Also look for the Nuclear Weapons and Small Arms threads, which I’ll hopefully have up within a month or two.



Engines
One of the most important, and misunderstood, aspects of aircraft are the engines. Few players understand the different types of engines, and even fewer know their strengths and limitations, so I will be providing a brief description on those. However, first we’ll look at some general aspects of engines and speed.
For starters, all engines produce thrust, which is what moves the aircraft forward. This is measured as a weight. For example, an F-100-PW-229 turbofan can generate 29,000 lbs (13,152 kg) of thrust on full afterburner. The comparative amount of thrust compared to the weight of the aircraft (thrust/weight ratio) is one of the major factors in determining aircraft speed. Most combat aircraft will opt for a high ratio, which will give them greater speed and climbing capabilities. When the thrust produced exceeds the weight of the aircraft, as it can in ones like the F-15 and F-16, the aircraft can perform some impressive feats, such as accelerating straight up.
It should be noted that things like speed and range are quite relative, and these can change dramatically based on load and altitude of the aircraft. For example, while an unloaded F-15E could pull up to Mach 2.5 (2660 km/h) when flying at about 35,000 ft. However, the same aircraft will be limited to Mach .74 (908 km/h) when fully loaded and flying at low altitude. The combination of practical limitations, increased air resistance, and increased drag from the weapons will all serve to greatly reduce its efficiency. The same goes for range. The aircraft will perform better at certain altitudes and speeds, and loading external fuel tanks instead of ordnance will help increase range.
Now, as for engines, there are a few things to note. One important one is that all engines mix air with fuel, which is ignited to either propel the aircraft forward through the exhaust or drive a propeller or rotor shaft. With the exception of rocket engines, which carry their own oxidizer (air substitute) with the fuel, current engines rely on compressed air taken from outside. As a rule, the greater the compression (pressure), the more thrust an engine will be able to develop. Therefore, most improvements in engine design are either to increase compression, of allow for increased compression, as this is the single most important factor.
Another thing that can be used to increase thrust is an afterburner. This system, which is present on most fighter and many bomber aircraft, allows for raw fuel to be dumped into the final combustion chamber, where it mixes with the exhaust and ignites, further increasing thrust, though it will consume fuel at a phenomenally higher rate.
Now, these are just some general things that apply to most engines. There are many different types of engines, and they can be quite different in both performance and operation. In here, I’ll look briefly at the engine types that are likely to be seen today, and I’ll try to steer clear of being to technical.

ROCKET ENGINES have only been used on one combat aircraft, the Me-163B Komet from WWII. Though such engines provide exceptional speed and are very popular with missiles, they have a major drawback, and that is that they consume fuel at a phenomenal rate. The Me-163B had enough fuel for only about 4 ½ minutes of powered flight, with the rest of the flight being gliding. Similarly, the vaunted X-15 only carried enough fuel for 80-120 seconds of powered flight, which amounted to only 1/5 of the total flight time. Most rocket powered aircraft were experimental units, notably the Bell X-1 (world’s first supersonic flight), and the X-15 (highest altitude and fastest aircraft – 354,200 ft & Mach 6.7). The greatest advantage of rocket engines is that, unlike jets, they require no airflow to operate. This makes them ideal for use on spacecraft and supercavitating systems. The high speed also makes the excellent for short-range missiles. However, on the reciprocal, rocket fuels require their own oxidizers, unlike jet engines, which use the air for that. This means that they require a greater volume of fuel to operate.

CENTRIFUGAL FLOW TURBOJETS were the first jet engines. They powered WWII aircraft like the Me-262 and Meteor, and later the F-80, F-86, and MiG-15 from the Korean War. These used a pump-like impeller to compress the incoming air flow, which limited the pressure ratio (the defining characteristic in engine performance), provides significantly reduced thrust. As one might note, none of the aircraft that used them could break the sound barrier. These are cheaper engines due to the lower heat and greater simplicity, but are not as fuel efficient as turbofans.

AXIAL FLOW TURBOJETS appeared in the mid 1950s on aircraft like the F-100 and MiG-19, which were the first supersonic combat aircraft. These are very similar to centrifugal flow turbojets, but contain a series of axial compressors that increase the pressure of the air. Kicking in the afterburner in these engines allowed brief supersonic dashes by providing an increase in thrust of up to 50%, but this consumes fuel at 3-4 times the normal rate. This engine design stayed with new aircraft designs into the 1960s, and some aircraft that used it, such as the F-4 Phantom II, still serve in modern militaries today. As with centrifugal flow turbojets, these lack the fuel efficiency of turbofans.

HIGH-BYPASS TURBOFANS appeared in the 1960s. They differ from turbojets in that they only push part of the air flow into the main compressor, with the rest of the air being diverted into a bypass duct and remaining unused. Now, this helps because the amount of air being used, more work can be done on a smaller volume of air, providing increased pressure ratio, and this was combined with a faster spinning compressor to further increase the advantage. In most high-bypass turbofans, 40-60% of the airflow is vented away, with some designs reaching as high as 95%! These engines provide advantage in a combination of high speed and a fuel efficiency that’s almost as good as turboprops. However, the problems that arise make them quite expensive. But despite higher cost, the advantages could not be ignored, and turbofans have been the engine of choice for all combat aircraft since the 1970s. Turbofans provide a massive increase in top speed, with full afterburner increasing speed by up to 65% instead of the 50% in the turbojet. However, this is countered by the fact that the afterburner consumes fuel at a 25% greater rate than that on a turbojet, but even without afterburners, turbofans can produce more thrust than many turbojets can even on full burner, allowing larger aircraft to be built while still maintaining high subsonic cruising speeds. Turbofans are also quieter than turbojets. The only real weakness of a turbofan, aside from cost, is the fact that it is still optimized for subsonic speeds. This means that supersonic flight, while it can be achieved for longer periods than in turbojets, still requires an afterburner.

LOW-BYPASS TURBOFANS are among the newest engines entering common military service. These work in a similar manner to the high-bypass turbofans, but only vent 15-20% of the air into the bypass duct, making them much more like turbojets. This allows for the supersonic cruising speeds of modern aircraft, but at a cost of top speed, as the greater volume of air, which is more like that of a turbojet, knocks down the boost provided from afterburning.

TURBOPROPS are similar to turbofans in concept, but use a turbine to drive an external propeller for thrust. In general, the jet portion only provides about 15% of the engine’s thrust, with the propeller doing the rest.. The primary advantage of these engines is the greatest fuel efficiency of any engine type, providing exceptional range and endurance. They’re also somewhat less susceptible to low-level hazards like birds, which can disable jet engines if they’re sucked into the intakes. Finally, they have the benefit of lower operating temperatures than jet engines, making them much easier and cheaper to make and maintain. On the downside, they are the slowest modern engine type, with even high subsonic speeds being quite unlikely with them. They are also known to provide a rough ride due to vibration, which means turboprop aircraft are much less comfortable for passengers than jet-propelled ones. Finally, their placement is more restricted (wings only) than jet engines. The only major turboprop equipped combat aircraft in service is the Soviet Tu-95 (equivalent to B-52). However, they are very common on transports and patrol aircraft such as the C-130 and P-3.

RAMJETS are a further development of turbojets, with the idea being to eliminat all the moving parts and allow the motion of the engine itself to compress air. These provide phenomenal speed (Mach 2 to Mach 5), rivaling that of rockets. At very high speeds (Mach 3+), these are extremely efficient engines, beating out turbofans and even turboprops for fuel economy. The lack of moving parts also makes them rather cheap, though the extremely high operating temperatures (and thus necessary materials) help to counter that. The greatest problem is that, since these require the engine to be moving at a decent speed (about Mach .4) before they can even be used, they have not been popular in anything but missiles. After all, a second engine or a booster would be required just to get the ramjet working.

SCRAMJETS (Supersonic Combustion RAMJETs) are another type of ramjet, and provide the greatest speed of any engine available. These engines require extremely high speeds to initiate (about Mach 2), and have even higher operating temperatures, both for the engine and the aircraft it propels. However, these provide efficient Mach 5+ operation, and can push aircraft even beyond Mach 10. Naturally working with the heat required for these and anything that uses them has been prohibitive, and that alone has caused great trouble with them. Once that hurdle is dealt with, there’s also the problem of getting an aircraft or missile up the required speed without taking up too much weight and/or space for boosters or other engines.



Stealth
Contrary to what is still popular belief, stealth aircraft are not invisible. Rather, they use several techniques to reduce their signature to the point that they are difficult to detect. Another myth is that they will always have this tiny signature. Even the B-2 can be detected by your average search radar if it gets close enough. However, such radars can’t detect it until it gets within a few dozen kilometers, so it can fly around the detection zone without having to go through it like most other aircraft.
There are two main kinds of sensors against aircraft (Radar & IR), and several methods of reducing the signature of each.
For starters, there’s radar. Radar systems work by focusing a beam of electromagnetic energy and detecting any that is reflected back to them. The amount of energy reflected back by a target is called the Radar Cross Section (RCS), and indicates how well and how large an object will appear on a radar screen. RCS is measured as an area, and the stealthier something is, the lower its RCS is in proportion to its actual size. Thus, the best way to defeat radar is to reduce the RCS, which means that the signal that is returned to the receiver needs to be reduced as much as possible. There are two primary ways to do this: shaping and RAM. Both of these have can trace their origins as far back as WWII, particularly Germany.
RAM stands for Radar Absorbent Materials, and are composites that absorb more of the signal than normal materials, leaving less to reflect back. Usually, these materials are not very strong, and are thus applied as coatings over more traditional metals. The earliest ones date back to the 1940s, and by 1943, Germany had two kinds of RAM coatings, known as Jaumann and Wesch, which were applied to the snorkel masts of their U-Boats, and reduced the detection range of these masts from 8 miles (12.8 km) to 1 mile (1.6 km). However, these were still difficult to maintain, and didn’t adhere well to the masts when immersed in seawater for extended periods of time. Modern RAM coatings are a little more reliable (though the maintenance problem persists to this day), and can absorb up to 90-95% of the radar energy that strikes them. These are used in several ways: One of the most common is as an appliqué material for combat aircraft, which can be applied to reduce radar cross section, with one of the most notable ones being the radar absorbing paint (Iron Ball) that the US supposedly uses. When applied to non-stealth designs like the F-15 and F-16, these coatings can reduce RCS by as much as 70-80%. The other common method is to use Radar Absorbing Structures (RAS), which consist of a rigid, hollow structure made strong, radar transparent (ie the energy passes through them rather than being reflected) composites that are filled with RAM. The best designed of these can absorb up to 99.9% of the radar beam’s energy.
Shaping, unlike RAM, must be built into the aircraft design. However, it’s far more effective at reducing RCS when used properly. Shaping works by changing the directivity (how much energy travels back toward the receiver). Specifically, the radar beam is most efficient when it strikes the target at a perpendicular (90 degree) angle, and the further from perpendicular the target surface is, the less energy is reflected back to the receiver, with the rest being deflected away from it. Now, this can be a very effective method of reducing RCS. A simple tilt of 10 degrees from perpendicular will result in about 97% of the energy being deflected away, and going further to 30 degrees will take this up to 99.9%. Now, there are actually several different kinds of shaping. The F-117A, for example, uses numerous faceted surfaces (think a gem or disco ball) to direct the radar energy away. The B-2 on the other hand, uses a technique called platform shaping, which gives it a smoother look, but has the same basic effect. Another important part of shaping is the basic airframe design. Simply put, the sharp breaks between the wings and fuselage and the tail surfaces of most aircraft greatly increase RCS. The solution, as seen in the F-117A and, even more notably, the B-2A, is to eliminate these altogether with a flying wing design. Now, the advantages of this design were known even in WWII, and both the US and Germany had prototypes for such aircraft. However, both ran into one major problem: the flying wing, like the forward swept wing on the X-29 and Su-47, is extremely unstable, and it wasn’t until appropriate computer systems could be developed that this design became viable. Now, however, you cannot make a truly stealth aircraft without it, though there is one other notable drawback, and that’s the fact that flying wings are very slow designs. Due to air resistance and structural limitations, these are solidly subsonic aircraft.
There are also some notable myths regarding stealth that need to be addressed. The first and most significant of these is that stealth reduces the range at which an aircraft or projectile can be detected by radar, but does not make it undetectable. The closer an aircraft gets to a radar, the less effective the stealth features will be. Most notably, the shaping that is the most popular technique will lose effectiveness as a greater portion of the energy will be reflected close enough to be gathered by the receiver. Now, though specific ranges have been given, the detection range rather relative, while a radar that can detect a B-52 from 366 km must be within 36.6 km to detect a B-2, another more powerful one might be able to see a B-2 100 km out, and a weaker one might need to be within 3 kilometers to see anything. In the end, the advantage of a stealth bomber is not so much to fly through radar defenses, but to create holes in a network’s coverage so the aircraft can fly around them.
The other method of detecting aircraft is infrared (IR), which is used to detect the heat given off for the aircraft. Now, IR is nowhere near as effective as radar for a long-range detection system, as current ones have very limited range, especially compared to radar. However, as a short-range detection system, it’s become very popular, due mainly to the fact that IR detection systems cannot be detected by passive sensors. IR is also popular in smaller missiles, as IR seekers are simpler and don’t require as much space as radar ones. Now, there are two important types, or windows, of IR that can be used to detect an aircraft, based on wavelength. Mid-IR, which includes the heat given off by the engine parts and exhaust, is used by many IR guided missiles. Long-IR, which is what’s caused by the sun heating surfaces and the friction caused by moving through the air, and is used by several more modern missiles, as it allows for engagement at any angle. Modern detection systems, including FLIR (Forward-Looking InfraRed) and IRST (InfraRed Search and Track) systems used by aircraft can search for targets in both windows, providing a dangerous short-range detection system. Because of this, true stealth aircraft need to be difficult to detect by IR as well. Part of this (Mid-IR) can be helped by eliminating the afterburner, which causes a good deal of heat. In addition, one must take steps to cool the engine exhaust, which usually entails designing the inlet so that cool ambient air will mix with the hot exhaust gases, dropping their temperature. Though this is not going to be a phenomenal drop, it’s enough to greatly reduce the signature. This in turn must be combined with measures of dissipating exhaust such as the long-thin nozzles used in the B-2 and F-117 (which incidentally also block the view of the hotter portions of the engine). Long-IR, on the other hand, can’t be helped very much, but using certain composite materials with good IR dissipation qualities will help, as well as the obvious trick of flying at slower speeds and at night. With this in effect, the detection range for IR sensors is about that of radar ones. Of course, this means that the effectiveness of suppression measures against IR are quite limited, and further developments there could prove devastating to stealth aircraft.
Another notable myth is that you can make superfast stealth bombers. This is only partly true, as the same designs that allow aircraft to achieve, maintain, and operate at extremely high speeds will also have a larger RCS. In the leap to make the B-1, for example, a supersonic aircraft, it had to be designed with 10 times the RCS of the B-2. Granted, this is still a vast improvement over the older B-2, but as the aircraft get faster, this becomes even more pronounced, as many popular stealth features (particularly several forms of shaping) are not very aerodynamic. Sorry people, but this means that there aren’t going to be any Mach 3 bombers with the RCS of the B-2. Now this isn’t to say they can’t be stealthy, but they will not be anywhere near as stealthy as the B-2, F-117, or even the F-22. This comes from the fact that they’re generally limited to a degree of shaping backed up by RAM and RAS, however, RAM can’t be used much (it’ll peel off), and some areas will need greater strength than RAS can provide, thus bumping up RCS. And naturally, any engine that pushes aircraft past Mach 3 is going to show up like the 4th of July on IR, no matter what suppression features you add to it.
The final key to stealth is EMCON (EMission CONtrol). Specifically, many signals that aircraft send out, particularly radar and radio, can be intercepted by passive sensors, which can then use them to figure the location of the aircraft. For this reason, stealth aircraft do not use radars, and reserve radios for emergency use only. Laser targeting systems can also be dangerous, as passive sensors can detect them as well. The ideal detection, tracking, and engagement systems for a stealth aircraft are IIR (Imagine InfraRed) and EO (Electro-Optical). Both of these are passive, and thus cannot be detected. Both of these act like cameras, using either visible or infrared light to create a picture, which a weapon system can then be locked onto. Though short-ranged, they are the best ways of detecting and engaging a target without being discovered in the process.


Speed Glossary
Hypersonic: Refers to anything exceeding 5 times the speed of sound. This is faster than a mile a second at sea level.
Mach Number: The speed of an aircraft/projectile relative to the speed of sound. This is portrayed as a decimal with Mach 1 being the speed of sound, Mach 2 being twice the speed of sound, Mach 2.5 being two and a half times the speed of sound, etc.
Mach 1: The speed of sound. It changes based on air density (ie different altitudes). Mach 1 at sea level is about 1226 km/h (762 mph), while Mach 1 at normal cruising altitudes (35,000 ft / 10,500m) is 1063 km/h (661 mph).
Subsonic: Refers to anything that is flying slower than the speed of sound.
Supersonic: Anything exceeding the speed of sound. Generally considered Mach 1 - Mach 5.
Transonic: Anything flying at a speed of Mach .9 to Mach 1.4



Maneuverability
This is an area that’s really hard to quantify, though many have tried. One popular measure is by the load factor (the G forces the aircraft can stand up to), however, as will be shown later, this really doesn’t leave much of a gap. So, the real test of maneuverability comes in other aspects. These include speed, rate of climb, rate of turn, turn radius, and special techniques. Speed and rate of climb, as one might expect, are really measures of engine performance, and not much can be done to the aircraft without them. Rate of turn (how fast it turns) and turning radius (how much space it needs to make a turn), on the other hand, are affected by the maneuvering surfaces of an aircraft. There are a number of control surfaces that an aircraft can have, including rudders, flaps, leading edges, and canards, all of which are moving control surfaces that help to increase agility. In addition, there is the factor of thrust vectoring, which uses flexible exhaust nozzles to direct the thrust from the engines in different directions. Now this usually isn’t a great change, but even a small one can dramatically enhance the handling characteristics of an aircraft, or alternately eliminate the need for other control surfaces. There are two general types of thrust vectoring. The simplest is 2-D, in which the engines of an aircraft can direct the exhaust up or down to assist in maneuvers, or more importantly, to allow for slower takeoff and landing speeds. 2-D thrust vectoring can be found on the F-22 and most VTOL aircraft. 3-D thrust vectoring, as found on the Su-47, on the other hand, allows for the exhaust to be directed from side to side as well, providing even further increased performance. One of the most notable advantages of thrust vectoring is the fact that it can eliminate the need for other moving control surfaces, which have a tendency to increase RCS. Thus, vectored-thrust aircraft can be stealthier.



G FORCES
G Forces are a measure of the physical stresses placed on pilots and aircraft during flight, as compared to the force of gravity on earth. Positive Gs are caused by an aircraft accelerating or pitching upward, and drive blood into the extremities. At +4.5-7g, a normal human can be expected to lose consciousness (G-LOC). Blackout (loss of vision) occurrs at 3.9-5.5g, and grayout (partial vision loss) at 3.4-4.8g. Modern G suits can allow pilots to remain conscious at up to +11g, though with the average suit, blackout can be expected at 9g.
Negative Gs are caused by an aircraft decelerating or pitching downward, and drive blood into the head, and the loss of vision for this is known as redout. -2g will cause redout in an unprotected human, and a good G suit will up this to –4.5g.
It should be noted that G Forces are caused by maneuvering and by changes in speed. If speed is constant, there is minimal additional force.
G forces were found to be a problem as early as the 1940s, when pilots were known to occasionally black out in high performance aircraft like the P-51 and Fw-190 while maneuvering. As aircraft became faster, it became necessary to provide measures to counter the G forces. The suits that were developed for this, known as Anti-G Suits (but commonly referred to as just G Suits), used tight straps to restrict the flow of blood in key areas, helping to decrease the effect that excessive Gs had on blood flow. However, even with current G suits, blackout occurs immediately at about +8-9g and redout at -4-4.5g. Because of this, no current aircraft is rated at greater than +9G / -4.5G, as no pilot can be expected to take it.
The same cannot be said of unmanned aircraft and missiles, however, and 60+ Gs is not unheard of for SAMs. Even current aircraft usually have the structural strength to maintain 15 Gs. It’s just that the pilots don’t, preventing them from pulling that much. However, this number can drop considerably when an aircraft is carrying external ordnance.

Below is a list of a number of aircraft and their rated load factor (maximum Gs):

COMBAT AIRCRAFT
AMX: +7.3G / -3G
AV-8B: +8G / -3G
EFA 2000: +9G / -3G
F-2A: +9G / -3G
F-14: +6.5G
F-15E: +9G
F-16: +9G
F/A-18: +7.5G
F-35A: +9G
F-35B: +7G*
F-35C: +7.5G*
F-117A: +6G
FC-1 (AKA Super 7): +8G
Harrier: +7G
JAS-39 Gripen: +9G / -3G
MiG-29: +9G / -2.5G
Rafale: +9G / -3.2G
S-37 Berkut: +9G
Sea Harrier: +7.8G / -4.2G
Tornado: +7.5G

TRAINERS/LIGHT ATTACK AIRCRAFT
ADA LCA: +9G / -3.5G
ALX: +7G / -3.5G (+4G / -2.2G w/ external stores)**
BAE Hawk: +8G / -4G, (+6G / -3G with full payload)
EADS Mako: +9G / -3G
HJT-36: +8G / -3G
JL-9 (aka FTC-2000): +8G
JL-15: +8G / -3G
KT-1: +7G / -3.5G (+4.5G / -2.3G w/ external stores)**
L 39ZA: +8G / -4G
L 59: +8G / -4G
L 139: +8G / -4G
L 159A: +8G / -4G
M-346: +8 / -3G
MB-339FD: +7.33G / -4G
MiG-AT: +8G / -2G
PC-7: +6G / -3G light (+4.5G / -2.25G at max take-off)**
PC-9: +7.5G / -3.5G light (+4.5G / -2.25G at max take-off)**
PC-21: +8G / -4G**
T-6A: +7G / -3.5G
T-45C: +7.3G / -3G
T-50 (aka A-50): +8 / -3G***
Yak-130: +8G / -3G

EXPERIMENTAL AIRCRAFT
X-31A: +9G / -4G

TRANSPORT AIRCRAFT
C-295: +2.53G (+2.25 in overloaded conditions)

HELICOPTERS
A-129 Mangusta: +3.5G / -0.5G
AH-1Z Super Cobra: +2.6G / -0.5G
AH-64D Longow Apache: +3.5G / -0.5G
EH-101 Merlin: +3G
RAH-66A Comanche: +3.5G / -1G
CSH-2 Rooivalk: +2.6G / -0.5G
UH-1Y Iroquois: +2.5G / -0.5G
V-22 Osprey: +4G / -1G




A $1 million dollar fighter?
This is a concept that’s been given a few times, and is one of the more annoying ones. So, just for fun, lets take a look at what such an aircraft would look like:

1. Stealth. This would be pretty much nonexistent. Why? Well, as said, stealth comes from one of two things. The first is RAM (Radar Absorbant Materials), and the second is from shaping. Well. RAM is expensive, as well as rather maintenance intensive, so that’s out. Similarly, the unconventional designs that mark stealthy aircraft are inherently unstable. That is to say that a human pilot can’t fly them without a great degree of assistance. Naturally, this comes in the form of expensive computers, which cost more than our $1 million limit.

2. Radar. Unless we’re looking at vintage Korea or WWII systems, this’ll cost more than our limit, so you can forget about it.

3. Engines. These need to be simple and can’t use expensive materials like titanium. Most likely turboprops or turbojets. A little over Mach 1 is possible, but subsonic is much more likely, as it would be better in terms of cost and maintenance.

4. Armament: Against aircraft, only guns and maybe short-range IR guided AAMs like the Sidewinder could be used. Naturally, radar guided missiles would not be workable. For air to ground, it can carry unguided bombs and rockets. It can also deliver laser guided ordnance, but it won’t have the designator!

5. Communications: Simple radio, and things like landing lights, maneuvers and hand signals could be used to help send messages as well.

6. Fire control: Simple sights, with maybe a lock-on signal for AAMs.

7. Construction: You can forget titanium and advanced composites. Work with simple steel and aluminum.

And here’s your product (http://www.wpafb.af.mil/museum/air_power/ap40.htm)

That’s right. Even the MiG-21 or F-100 would cost several million today, as do many 1950s and pretty much all 1960s or later aircraft. Look to the Korean War or WWII for your $1 million fighter. Anything much more modern isn’t going to work.






*This is for the Boeing proposals. The Lockheed aircraft may be different, but it’s more likely that the load factors will be very close, if not identical to these.
**These are actually turboprop trainers rather than jet aircraft.
***A-50 is the designation for the combat version, which is a light attack aircraft. T-50 is for the training version.

Can I have one? I like airplanes

Still won't solve the problem.I know, but would it not help any?

Still won't solve the problem.I know, but would it not help any?Yes, but you'll eventually hit a break-even point where any further refinement won't produce noticable results.
I'd show you my Aero/Astro homework, but I'm so damn tired of that class that I'd go insane. INSANE I TELL YOU!!!

[tag]

CSJ, are you planning to put these together, maybe on an NS external page?

Yes, but you'll eventually hit a break-even point where any further refinement won't produce noticable results.Okay, that's what I thought.
I'd go insane. INSANE I TELL YOU!!!Okay.

RAMJETS are a further development of turbojets, with the idea being to eliminat all the moving parts and allow the motion of the engine itself to compress air. These provide phenomenal speed (Mach 2 to Mach 5), rivaling that of rockets. At very high speeds (Mach 3+), these are extremely efficient engines, beating out turbofans and even turboprops for fuel economy. The lack of moving parts also makes them rather cheap, though the extremely high operating temperatures (and thus necessary materials) help to counter that. The greatest problem is that, since these require the engine to be moving at a decent speed (about Mach .4) before they can even be used, they have not been popular in anything but missiles. After all, a second engine or a booster would be required just to get the ramjet working.

To solve this couldn't you use sky ramps they're a simple answer, and the assisted launch they provide greatly extends the range of the aircraft. Launched at a thirty degree angle would be sufficient to provide reductions in fuel useage, especially if there was a downward slope to the launch thus taking advantange of gravity for a free increase in speed. So the need for an expensive booster or second engine isn't really needed, course the return journey would have to be a matter of gliding or a small jet engine to aid in powering flight home.

Not yet had time to fully digest the post, but it looks excellent. Kudos.

Remembering the, also excellent, post on ships, but having missed the one on tanks, how about lumping them all together at somepoint and we look for a tame mod to sticky it?

As a side note on Gs, the formula goes a= v^2 / r , where g=10a or 10m/s^2 . So the faster you travel the larger your turning radius.

(This is also a tag)

Nothing about Pulse Detonation Engines, CSJ? I was wondering about the viability of those in aircraft.

PDJs are currently in the "tinkering" phase of research. While they are far more fuel efficient than, say, turbojets, they definitely break all noise-pollution regs at the moment.

Overall, a good summary. I can provide equations for determining aircraft performance if anyone wants 'em @_@

http://www.weirdozone.0catch.com/projects/nationstates/scolopendra/hapc-scolo.gif Hearty Aerospace Pirate Cap'n Scolo

A fine and detailed post indeed. So how does everyone here rate my JH-15:

http://forums2.jolt.co.uk/showthread.php?t=339785

What would you say the lower limit for size on a ramjet plane with a gun and a few missiles is?

Great post (although i havn't had time to fully read it), but you forgot one thing fro scramjets: no aircraft powered by scramjets has yet had a free flight.

Another outstanding post, CSJ.

I certainly support a "STICKY THIS!" campaign.

We really ought to find someone to replace the excellent Nanakaland thread, link this and a few others to it (such as your tank and warship threads), and sticky that.


TEO

bump

~TAG~ for later reference.

TAG so I can read later.
Thinkers Are Great

Some things in this thread a VERY wrong.

Flying wings have a LOWER drag than conventional designs. Thats why they were invented, to have the lowest drag possible and this was down by not having any tail surfaces. Flying wings have LESS drag but arn't as stable for obvious reasons.

As for the 1million dollar fighter. You could have active radar missile but the missile will cost more than 1million but would be launched by anything. In the Vietnam war several long range active radar missile were made.

There is no such things as an "invisible" aircraft. Stealth designs are very effecive at the opening stages of combat or when the enemy has almost no air defense. A stealth aircraft can easily be detected by a high power radar such as a patriot while it will be very close when detected it is possible to shoot it down for it drops it's bombs.

RAMJETS have TERRIBLE fuel efficency. This is becuase they have extremly low compression ratios. A ramjet has a TSFC of around 2.1 while even a turbojet has one around 0.9 and turbofans 0.5. You will be getting a better fuel economy with full afterburner on a turbofan than a ramjet. (For those that can't understand what TSFC is. 2.1 mean that the engine burns 2.1lbs of fuel for every pound of thrust made per hour. so a 100lb thrust engine will burn 210lbs of fuel per hour while a turbofan will ponyl burn 50lbs or fuel).

The same goes of Pulse Detonation engines. They are better they still have a TSFC of around 1.3. They are NOT good engines.

A fascinating and well-written post, but there is one thing I think needs to be raised:

There were actually two other Rocket Aircraft used in WWII, besides the Me-163 Komet.

They were the Ohka (Cherry Blossom) Kamikaze Rocket used by the Japanese, and the "Natter" experimental Rocket Fighter that was combat tested by the Germans once or twice, IIRC.

The Ohka was dropped from the belly of a "Betty" bomber and piloted into ships or whatever- there's still some debate whether it was an Aircraft or Piloted Bomb.

The "Natter" was used once or twice in either extremely late 1944 or early 1945 against American Forces, IIRC. By that time, of course, the Germans really had more important things to worry about and the project was discontinued... The fact it had no Landing Gear can't have helped the search for Volunteers, either (the pilot was supposed to eject when he'd fired all his rockets).

#tag#

As for the 1million dollar fighter. You could have active radar missile but the missile will cost more than 1million but would be launched by anything. In the Vietnam war several long range active radar missile were made.
Well, I don't exactly know where you got your information from, but at least the line of American AAMs in that era didn't have much developments in the active radar arena. Active radar missiles can be cheap, unless you mean the big huge type that the F-14 carries. Neither were much of the Soviet missiles equipped with an active radar.


About the rocket aircraft thing, I'll agree with Roycelandia. But you have to remember that the Me-163 is the only rocket aircraft that got into service, and did shot down enemy aircraft. Personally I'm not a Japanese WWII aircraft person, but I don't think that the Natter scored a lot of hits nor went on more combat sorties anyways. And the Komet is still one of my favourite WWII aircraft :)

If anyone is interested, there's also the Soviet BI-1 rocket aircraft, but that didn't get very far either (supposebly the Soviets dropped their interest and looked for other ways to defend their capital from the German bomber threat).

I'm well aware of the other aircraft (the Japanese also had the J8M, which was essentially a licensed version of the Me-163), but the only truly operational combat aircraft was the Me-163. The Natter was only experimental, and the Ohka was more of a manned missile than a combat aircraft (remember, it was launched from a bomber specifically to fly into ships).
The problems with the Me-163 included extremely volatile fuel, which caused several to blow up during takeoff, and the fact that most of its flight was unpowered, which gave little room for maneuvering. Thus, while the Me-262 was easier to shoot down, it was more effective in engaging fighters and ground units.


Nomadic League, I believe you'll find that while ramjets are indeed inefficient at subsonic and transonic speeds, once you get above the Mach 3 range, they indeed become quite competitive. However, that makes them of limited use on most combat aircraft as those kind of speeds are only useful for interceptors. The ATR concept can also help solve the subsonic issue by operating as a turbojet at lower speeds.
And just curious, where was it ever said that an aircraft could be truly invisible? I just can't find anything to that effect. In fact, I kept emphasizing the opposite.

I realize this posting's focus is on aircraft propelled by thrust from the engine's exhaust, however, I must mention two overlooked items.

First, the Turboshaft engine, which is most commonly seen in helicopters; the turboshaft works like any other turbine engine, however, power is harnessed by (commonly) two turbine rotors and transferred to a power shaft. The exhaust is then expelled through a divergent nozzle, decreasing the thrusting power behind it. The power shaft itself runs the entire length of the engine and connects to a drive shaft in the front (Save for some engine designs, such as the C30R3, Rolls-Royce, I believe, in which the power is transferred directly to a gearbox in the center of the engine, and then to a pair of drive shafts).
The power is then transferred to a transmission which drives the rotors of the helicopter. Instead of being dependant upon thrust-to-weight ratios, its dependant upon shaft horsepower.

On the note of Centrifugal and Axial Compressors:
Many turboshaft engines feature a dual-compressor; it has several stages of Axial compression, followed by a single Centrifugal Impeller (Example, the engines in the UH-60 feature 5 stages of axial compression followed up by an Impeller directly behind that). The dual-compressor design provides an even higher compression ratio, increasing the power produced by the turbine engine.
//EDIT: Changed 7 stages of axial to 5 stages, I mixed it up with the T55-714, the Chinook engine//
...Sorry. The trained Turbine Surgeon in me had to get that out :P

An excellent thread and well researched..... I would recommend the following book to ambitious Air Marshals..

How to Make War, 4th Edition, by James Dunnigan Harper Collins Books 2003

available in bookstores too... and only about $20

literally EVERYTHING a would be Alexander the Great needs to know..

also rates every single current military aircraft based on combat effectiveness, reliability and range, and goes into all kinds of things like why pilot quality if critical (for starters)

interesting little tidbits such as the Mig21, which for many years had a problem where if you used most of the fuel in the starboard (or port) wing, and did a sudden maneuver, you had the problem of fatal spins

gunsight didn't work for a while either

Which is not a good thing for an interceptor and air superiority fighter.. (which may be why the North Vietnamese and Chinese continued to use the Mig 19 for so long)

Anyway, check it out, its definitely worth a look.... James Dunnigan also has a good website (Strategy.com) and it has a message board with threads like this one

New Shiron, I believe you mean StrategyPage.com, no?

thanks for the correction... definitely, if you haven't been there, check out strategypage.com

Well, about the Me-163, I do recall that it did shoot down quite a number of B-17s. But overall, looking at its accident rate and other combat records, you could say that it isn't much of an effective aircraft. I do recall that landing also has to be percise, but with a skilled pilot who can get the aircraft near the B-17s within that short period of the time, the aircraft is the killer.

About the MiG-19 thing however, keep in mind that North Korea didn't have much MiG-21/23/29/J-7s (Chinese version of the MiG-21), and the MiG-21 is actually the mainstay of the Chinese PLAAF for many years now (I do recall that they do still have some domesticly-built MiG-19s in service, but not much). Hopefully with the J-10, the FC-1 (although the PLAAF didn't express so much interest in this one), and more Su-27/30 Flankers, the PLAAF could get on with modernization.

Well, about the Me-163, I do recall that it did shoot down quite a number of B-17s. But overall, looking at its accident rate and other combat records, you could say that it isn't much of an effective aircraft. I do recall that landing also has to be percise, but with a skilled pilot who can get the aircraft near the B-17s within that short period of the time, the aircraft is the killer.

About the MiG-19 thing however, keep in mind that North Korea didn't have much MiG-21/23/29/J-7s (Chinese version of the MiG-21), and the MiG-21 is actually the mainstay of the Chinese PLAAF for many years now (I do recall that they do still have some domesticly-built MiG-19s in service, but not much). Hopefully with the J-10, the FC-1 (although the PLAAF didn't express so much interest in this one), and more Su-27/30 Flankers, the PLAAF could get on with modernization.


As of 2000, the Chinese had roughly 3000 Mig19 (all version) and about 500 Mig21

I am not sure I want the Chinese to get Su-27s, but oh well, thats the breaks.... eventually they will have a good air force, they have pretty much always had a large one

I did actually mean to criticize the Mig 21, not the Me 163 (good point defense interceptor, especially for 1945, although crashing was disastrous for the pilot, the rocket fuel was so caustic it would dissolve flesh)

there used to be a good web page (I forget the link though) which compares Taiwan and China including all major military items like fighters, missiles and ships

there used to be a good web page (I forget the link though) which compares Taiwan and China including all major military items like fighters, missiles and shipsIs this (http://www.emeraldesigns.com/matchup/military.shtml) it?

Glad to see its still around... its one of the better web pages out there...

also good are the various US military branches, the British Royal Navy and the Australians have good ones as well

I am sure there are others, but a translation program will be needed most likely... I have looked at the Japanese Self Defense Force websites before and needed babblefish to figure out what was going on

http://www.geocities.com/pentagon/9059/usaob.html this site gives you a complete US order of battle by the way (although its pre 9/11 and many of the links no longer work for various reasons)

Clan Smoke Jaguar I think you will find that a ramjet get WORSE tsfc the faster it goes. At Mach 1 a typical tsfc is around 1.2, at mach 2 it rises to 1.5, mach 3 jumping to 2 and Mach 4 a whopping 2.8

This is while a typical turbofan will be doing around 0.9.

This is not to say that ram and scram jets don't have uses, a turbofan cannot be used above around mach 3 without bleeding some air, this is because the airflow inside the engine becomes supersonic and the compressors can't function properly and this is where ramjets come in. They will work happily at these speeds. No amount of venturi effect will help this.

I was backing you up on the invisible thing.

On a side note, the first rocket interceptor was russian. Not too sure of the name but it was the first to be tried but unfortunatly never went into service.

The "Natter" was used once or twice in either extremely late 1944 or early 1945 against American Forces, IIRC. By that time, of course, the Germans really had more important things to worry about and the project was discontinued... The fact it had no Landing Gear can't have helped the search for Volunteers, either (the pilot was supposed to eject when he'd fired all his rockets).

False, it was never used at all and only had one manned test flight on March 1st 1945, ending with the pilot Lothar Siebar being killed, this being the first ever manned rocket-powered take-off in history.

On a side note, the first rocket interceptor was russian. Not too sure of the name but it was the first to be tried but unfortunatly never went into service.

Yeah, that's the BI-1. A pretty good aircraft with successful test flights, though Stalin and his people eventually dropped interest. I don't recall when it flew first, but certainly beforet the Me-163.

Very well done. I know very little about the actual considerations of building and developing aircraft and this thread goes a long way to help explain them.

Nomadic, I think what he was trying to say was that flying wings have significantly increased amounts of drag in the transonic and supersonic flight regimes. They are quite efficient in the subsonic regime, though.

One engine that hasn't been talked about is the propfan or unducted turbofan. These are like turbofan engines but have no ducting around the fan of the aircraft. They produce an extremly high bypass ratios or anywhere from 14 to over 20, this makes them very fuel efficient at subsonic speeds. The disadvantage is they produce large amounts of noise. They are rated in Horsepower and a typical engine produced around 15,000hp.

Consider these when building large transport aircraft.