Defense Issues

Military and general security

Balancing a fighter design

Posted by Picard578 on September 1, 2017

Introduction

Producing a balanced fighter design is a key element of an effective air force. Yet it is also very hard, as tactical capability has to be balanced against strategical capability. “The best is the enemy of good enough” holds true for fighter design as it does for everything else. Fighter design is a balance of compromises, and focusing too much on one side of design leaves gaping holes in the other side of design. Amongst modern fighters, F-22 is tactically an excellent design but is garbage when it comes to strategic capability. F-35 is tactically good for certain ground attack missions (SEAD, DEAD) but worthless for other ground attack missions (CAS) and air superiority, and also strategically worthless. On the other side of the spectrum, original Su-27 and MiG-29 designs were adequate in strategic ability, but were tactically very lacking to say at the least. The only well balanced design in existence is likely Swedish Saab Gripen, with some other designs – F-16, F-18, Tejas and Rafale – being merely adequate.

Tactical capability

Situational awareness and emissions stealth

Sensoy suit should be primarily passive. This way, fighter will be able to achieve surprise in aerial combat. Since surprise is number one issue when gaining kills, all active emissions by fighter itself – radar, radio, dana links etc. – should be avoided. Where such emissions are necessary, they should be provided to the fighter by offboard means, such as unmanned aerial vehicles (UAV) and airborne warning and control systems (AWACS). This will allow fighter to achieve surprise, and deny enemy the opportunity to use fighter’s own emissions to find and possibly even target it. Issue with this approach is that IRST has limited rangefinding ability, though its angular resolution is superior to that of the radar. Rangefinding options exist, but passive rangefinding is comparatively imprecise, while active rangefinding warns the opponent. While a degree of surprise is achieved merely by initial detection being passive, even if active rangefinding gives away fighter’s presence, this still limits missile probability of kill as the enemy has time to prepare while a targeting solution is calculated and missile launches and traverses the distance. Completely passive surveillance and targeting avoids that issue, but at the price of more limited situational awareness due to range and scan time issues. IRST also has the advantage of not being easily jammed. Midwave IRST is better for ground attack aircraft due to lower susceptibility to aerosoil, while longwave IRST is better for air superiority fighters as it is less affected by water droplets, and can see straight through thin cloud cover. IRST also allows for detection of stealth fighters at useful tactical distances, and just as importantly, allows for somewhat reliable identification of targets, thus making BVR combat possible. By using PIRATE IRST as a basis, subsonic fighters may be detected at 90-160 km, depending on the altitude and aspect. Supersonic fighters may be detected at 250-500 km distance, again depending on the altitude and aspect.

Radar may be provided either onboard, or through offboard means. If radar is provided in an integrated package, care should be taken that a quest for radar performance does not compromise other fighter’s characteristics, such as size, maintenance or flight performance. However, small fighters are limited by radar’s output and aperture size. For this reason, and due to radar giving away fighter’s presence, an integrated radar is not an ideal solution. Another possibility for an onboard radar is a radar pod. This way, radar is not limited by the size of the fighter’s nose cone, and does not have to be carried by all fighters in a squadron. Radar may also be carried by a command fighter or an AWACS, preferably both. Command fighters would be large, twin-engined, two-seat fighter aircraft with extensive sensory suite. Ideally, they would have nose, cheek and rear sensory arrays – consisting of RADAR and IRST, and possibly LIDAR – as well as standard radar, laser and missile warners, providing a 360* situational awareness. Due to their relative vulnerability, they would be kept back while providing sensory feed to other fighters. Last option is AWACS. This aircraft is even larger and more vulnerable than a command fighter, but also has even more powerful radar. Due to relatively large crew, AWACS is an ideal coordination center, but even so maximum autonomy should be provided to fighter pilots and flights. Overall, a combination of radar pods, command fighters and AWACS aircraft seems to be an ideal solution. A radarless fighter design can be seen here. Offensive fighter however would likely not be able to rely on either AWACS or ground radars, and should thus be equipped with its own onboard radars. Ideally, it would have nose, cheek and tail X-band arrays, and leading edge L-band arrays.

Fighter should also have good cockpit visibility, with bubble canopy and general nose area design optimized so as to provide good over-the-nose, over-the-side and rearward visibility. Canopy would ideally be frameless, though a separate windshield may be provided so as to protect the pilot in the case of mid-air canopy failure (e.g. accidental ejection of the canopy).

Pilot training

Pilot is the most important part of the aircraft, and thus pilot training is the most crucial for performance, including survivability. Pilot training heavily outweighs any technical concerns. In war, 10% best pilots score 60-80% of all kills. During Battle of Poland in1939., a few Polish pilots became aces in 225 mph open cockpit biplanes while fighting against 375 mph Me-109 modern monoplane fighters. Meanwhile, during 1940 Battle for France, French and British pilots did poorly despite their fighters being as good as German ones, due to using incorrect tactics. Later Battle for Britain was not lost because of fighter production, but because Germans were incapable of recovering pilot losses: while 50% of British pilots shot down were recovered safely, all German pilots were lost due to fighting over a hostile territory. Likewise, air war against Germany in late 1944 was won because Germans were not able to replace fighter pilots at adequate rate.

Training is made easier by simulators, but live training in actual aircraft is still irreplaceable. Consequently, pilot has to be able to fly regularly, and often – one hour per day or more. To fulfill this requirement, aircraft has to have several characteristics. It has to have low maintenance downtime, low operating cost and high system reliability. Peacetime availability has to be high to very high, which is achieved by having adequate ground crews as well as an excess of spare parts and fuel available. Ideally, there would be an excess number of fighter aircraft compared to pilots, for two main reasons. First, such a situation would mean that pilots are not limited in training and combat by their machines. If a fighter aircraft is not available due to damage or maintenance, pilot simply uses a spare one. Second, it would provide a pool of spare fighters to be cannibalized if spare parts are not available for whatever reason. This situation should be avoided as much as possible, but expecting it to never happen is moronic. To achieve this however, fighter aircraft has to have both low procurement cost and low operating cost, combined with high reliability. All these requirements lead to a final requirement for a small, simple fighter design. Fighter should also be single-role, as single-role aircraft and especially single-role pilots are far superior in their designed role than aircraft and pilots carrying out multiple roles.

Human-machine interface

In order to simplify both training and operation, allowing pilot to focus on tactics instead of managing the aircraft, interface has to be simple and intuitive. This can be achieved through usage of design utilizing large touch screens with as few switches and buttons as possible. Another important factor is the ability to optimize HUD/HMD symbology so as to avoid cluttering. This would ideally include the ability to quickly switch between different programmed HUD layouts, as required by the situation. Layouts themselves should be as minimalist as possible. This would reduce the amount of information forced onto the pilot by the aircraft systems, allowing him to focus on actual combat. Each pilot should be given possibility to personalize HUD and screen layouts. Information should be presented in a graphic form as much as possible, with numbers and letters being used only where absolutely necessary.

Physical stealth

Aircraft should have as low visual, IR and EM signature as possible. Visually, this means that fighter itself should be small, less than 15 meters in length and 10 meters in wingspan. It should also be painted light gray, and have as few protrusions as possible. Care should be taken to ensure that engines have as little smoke emissions as possible, regardless of the operating conditions, as smoke can increase visual detection distance by a factor of 3 to 5. As noted before, situational awareness should be provided primarily through passive means, and aircraft should have an option of IR BVRAAM.

While internal weapons carriage is not an option due to other concerns, radar cross section should also be minimized. There are several approaches which can minimize RCS on conventional fighters. First, airframe should be optimized so that there is a minimum number of unnecessary protrusions – everything should be flush with the airframe. Refueling probe can be internal, or else aircraft could use boom refuelling so that fighter itself has no protrusions. Missiles should be carried conformally, with ideally two wingtip stations and two to four body stations allowing for conformal carriage. This way, missile rail as well as a gap between the missile and aircraft’s airframe would be eliminated. Missiles themselves should have retractable wings, which would eliminate scattering from the missiles as well as the possibility of missile wings acting as corner reflectors. Aircraft’s wings and canards should both be canted – downwards for wings, upwards for canards – not only to achieve adequate separation for aerodynamic purposes, but also to avoid forming a corner reflector with vertical stabilizer. This approach would also prevent missile winglets, if conventional missiles are carried on wingtip stations, from forming a corner reflector with coplanar radar source.

In IR spectrum, aircraft should be capable of supercruise so as to minimize the need for afterburner. This should be reinforced by having high thrust-to-weight ratio, even on dry thrust. Consequently, engine should be capable of achieving high percentage of total thrust without afterburner, pointing to a low bypass ratio, possibly even a turbojet. Engine woud have dual nozzles, with outer nozzle hiding the hotter inner nozzle as well as the hottest portion of afterburner. Additional cooling channel may also be provided, coupled with the outer nozzle. This cooling channel would utilize cool air from the boundary section layer, instead of the hotter air provided by the engine itself. Aircraft should be aerodynamically well designed and small, so as to minimize the engine emissions necessary. Air exhaust for the electronics cooling would lead into the engine air duct, so the hot air would be ejected with already superheated engine exhaust.

For a multirole fighter, acoustic stealth is also important. This means limiting the aircraft size, weight and thus engine power. Aerodynamic design should also be with as few protrusions as possible in order to eliminate irregularities in the air flow.

Weapons

Weapons should allow both quick reaction during close combat and silent kills during long-range combat. As a result, normally used weapons would be 30 mm revolver gun, short-range IR missile, medium-range IR and dual mode RF/anti-radiation missiles, and long-range dual mode RF/anti-radiation missiles. Missile ranges should be in brackets of 25, 50, 100, 150, 300 and 500 kilometers. Going with noted, IR missile option should be present for missile ranges of 25, 50 and 100 kilometers, with RF/AR missiles being available for ranges of 50 kilometers and greater. Usage of IR missiles would result in improved reliability as well as reduced vulnerability to countermeasures.

Fighter should have at least one onboard kill in adverse conditions. Assumed probability of kill used here are 0,31 for revolver cannon, 0,26 for rotary gun, 0,15 for IR WVRAAM, 0,11 for IR BVRAAM and 0,07 for RF BVRAAM against uncooperative targets. Against cooperative targets, Pk values assumed will be 1 for gun, 0,73 for IR WVRAAM, 0,59 for IR BVRAAM and 0,46 for RF BVRAAM (pilot training and situational awareness are the primary determinants of aircraft’s ability to avoid the missile). With four conformal stations – two wingtip and two body stations – and four wing stations being assumed, fighter should be able to carry eight missiles, plus 6 gun bursts to allow for two kills. In “stealth” configuration, with two IR WVRAAM and two IR BVRAAM, total number of kills is 2,38 against uncooperative targets and 8,64 against cooperative targets. If normal configuration is assumed to be two IR WVRAAM, two IR BVRAAM and four RF BVRAAM, total number of kills should be 2,66 against uncooperative targets and 10,48 against cooperative targets. BVR missiles overall have limited effectiveness against fighter aircraft, and are mostly useful against large targets such as AWACS or transport aircraft. They are useful when pursuing a retreating target due to longer range, and can be used to force the enemy into unfavourable situation for the merge. It should also be noted that the missile effectiveness noted here is for visual range only; at BVR, BVRAAM Pk is halved compared to the values noted.

In order to maximize kill probability at beyond visual range, BVRAAM should be of a ramjet design, so as to maintain thrust during the terminal phase. Long-range BVRAAMs could combine ramjet primary missile with solid-fuel rocket secondary stage, coasting in a ballistic path until close enough to target. Unless this is done, there is no chance of a BVR missile hitting an aware target outside the visual range, as it will lack energy and maneuvering capacity to do so – probabilities of kill noted earlier are all achieved within visual range. Probability of kill at altitude is low even with maneuvering ability intact. A missile that pulls 40 g at sea level will only pull 13 g at 10.000 meters and 2,85 g at 20.000 meters, unless 40 g is a structural limit. AIM-9 for example can pull 40 g at SL and at 10.000 ft, and 35 g at 20.000 ft. At 40.000 ft, AIM-9 should be able to pull no more than 13 g. Meanwhile, F-16 for example can sustain 9 g at up to 10.000 ft, and Rafale can sustain 9 g at 40.000 ft. In terms of more relevant (for missile evasion) instantaneous turn performance, F-16 can pull 9 g at altitudes up to 35.000 ft; at 40.000 ft, maximum limit is 7 g, and 5 g for most of the envelope. Missile on the other hand needs at least five times the g performance of a fighter aircraft to achieve a hit, possibly even more (lowering the speed of a missile does not improve turn rate as missiles typically operate well below their corner speed). As it can be seen, even AIM-9 is very unlikely to hit a maneuvering F-16 at 20.000 ft, and basically impossible to hit it at 40.000 ft. As a consequence, fighter aircraft should carry a large number of missiles and be able to fire them in pre-programmed salvos if goal is a BVR engagement. If fighter is optimized for visual-range combat, it should be able to carry missiles conformally, and fire them even from high off-bore angles, as well as to maintain missile lock during rapid maneuvers so that pilot can fire off a missile immediately upon achieving a desired position.

Gun is most likely to be used against large, undefended targets such as AWACS or transport arircraft in order to avoid wasting missiles. Other scenario is usage against targets that are too fleeting to achieve a missile lock, or are within missile’s minimum engagement distance. As a result, premium is placed on damage output in quick bursts. Firing opportunities in a dogfight are brief, and length of a burst is never longer than 1,5 seconds. This means that gun has to pump out as much damage as quickly as possible, which in turn requires quick acceleration and high HE-I content of the shell. Overall, the best choice is a high-calibre (30 mm) revolver cannon.

Kinematic performance

Aircraft should be capable of supercruise, so as to minimize the infrared signature while supersonic, as well as extending the time it can spend at supersonic speeds. This would allow the pilot to surprise the enemy from the rear, and avoid getting surprised himself. It would also allow it to dictate the terms of the engagement, avoiding the unfavourable engagements. Supercruise speed goal should be at least Mach 1,5 with six conformal missiles and no external fuel tanks. Fighter should be able to spend at least 20 minutes at that speed in the combat zone. Combat radius calculations should include the supercruise as well as combat. For defensive purposes, fighter should be assumed to operate without external fuel tanks, while in offensive purposes normal load would be six missiles and two to four external fuel tanks. Therefore, 300-400 km combat radius with 20 minute supercruise on internal fuel would be acceptable performance. This will likely lead to fuel fraction of 0,35-0,45, depending on the aircraft performance, aerodynamics, engines and size. For a dedicated offensive design, target combat radius would be 500-800 km with 20 minute supercruise on internal fuel.

Fighter should have 9 g turn capability in both instantaneous and sustained turn. If possible, 11 g instantaneous turn capability should be pursued as normal performance, with 13 g in override. Roll onset should be very rapid in order to allow fast transients, both in level flight and during the turn (at angle of attack). This is important for both dogfight and missile evasion purposes, as missile guidance lags behind an aircraft. Climb capability should be at least 300 m/s when clean at sea level, >350 m/s if possible. Ideally, turn rate would be above 30 deg/s instantaneous, 24 deg/s sustained and 300 deg/s roll rate. Fighter should be able to both gain and lose speed quickly, to allow outmaneuvering the opponent in a dogfight, as well as missile evasion. For this, moderate-to-high sweep tailless delta is a best choice. Engine should be turbojet in order to allow for quick changes in fan rotation rate and thus engine output – larger diameter of turbofan engine leads to comparatively more sluggish response. Just as importantly, turbojet engine should be capable of achieving higher thrust-to-weight ratio, especially at dry thrust. This would reduce the need for afterburner, leading to improved persistence even though fuel consumption at same engine setting will likely increase. Fighter’s combat weight should be low in order to reduce inerta and allow quick transients that are key to winning an air engagement. Reduction of roll inertia specifically can be achieved through single-engined configuration, low wing span, and locating heaviest ammunitions as well as most fuel as close to the aircraft centre as possible. Offensive design however would do well with two engines so as to ensure backup in the case of a failure or a hit by a SAM or AAA, in order to get the pilot back to the friendly territory.

Strategic capability

Ground survivability

Despite the name “air craft”, modern aircraft – especially fighter jets – are less air craft and more air hoppers. Fighter aircraft in particular spend only a portion of time in the air – no more than a third, and many far less. Most of the time is spent on the ground, undergoing maintenance, repair, refit and refuelling. As a result, ground survivabilty is a crucial aspect of aircraft survivability. To achieve this, fighter should be capable of operating from road bases. Minimum takeoff and landing distances should be less than 500 and 400 meters, respectively. Wingspan should also be less than 8,75 meters for a defensive design. A dedicated offensive fighter would likely have to have larger wingspan as well as longer takeoff and landing distances, thus placing emphasis on dirt strip performance. Logistics requirements should also be low, in particular in terms of spare parts and fuel. Low fuel usage means that fighter itself should be relatively small. Easy repairability in field would mean usage of aluminium alloys instead of composites, though decision should be made after taking into account impact on aircraft performance.

Numbers in the air

In order to carry out all the task, fighter force has to be able to launch enough sorties – best weapon in the world is useless if it cannot cover all necessary areas, and planet is a large place. Larger number of aircraft than the enemy’s also allows for tactical (as well as operational and strategic) flexibility, allowing one portion of the force to engage the defending fighters while remainder goes after crucial targets that had been left without cover. This means that fighter’s procurement and especially operating cost should be low, as well as its logistics requirements. Again, this leads to requirement for a small, easily maintained fighter aircraft.

Ease of maintenance

Aircraft should have a simple and maintenance-friendly design. Number of individual components should be kept to minimum, and all important components should be placed so as to allow easy access from the outside. Components themselves should be grouped into easily replaceable modules – which themselves should be repairable in the field. Minimum number of parts should be used in construction.

Logistical footprint

Logistical support is the most vulnerable element of any force. If supply chain is disrupted, the entire combat force is quickly rendered impotent. For this reason, minimizing logistical footprint for any given force is mandatory. Chain itself consists of several main elements. First one is the producer, albeit it is not always relevant in the war. Items produced in the factory are stored in the depots at home, and then shipped to military bases – which, in the case of expeditionary military forces such as the US military, are often overseas, requiring shipping over large distances. Once transferred over the sea, they are unloaded at port, and either stored there or transferred to inland supply depots. From there, items are transferred to military units and bases that require them (not all bases are large enough to function as supply depots on their own). In a specific case of fighter aircraft, the chain consists of manufacturers (aircraft parts, weapons, fuel), supply depots and air bases at home, supply depots / large air bases abroad, and forward operating bases (e.g. road bases).

Supply footprint of a fighter unit is not limited to fighter aircraft themselves, but also to any and all support elements – AWACS, tankers, air bases themselves, ground forces providing security for said air bases. Most modern fighter aircraft are large and complex machines, requiring dedicated air bases for operation. Such fighters themselves already have high logistical footprint due to complex maintenance and high fuel usage. Footprint is only increased by the equally complex tools required for maintenance – especially when it comes to stealth fighters such as the F-35. Further, air bases themselves require constant maintenance. Not only tools for fighter maintenance have to be maintained, but also the aircraft runway (FOD walks!), hangars, living quarters for pilots and ground crews. Dedicated air bases themselves are very vulnerable to attacks, and are also very lucrative targets. This means that they require security in the form of extensive missile and air defense systems, as well as powerful ground forces for defense against ground assaults. These forces require massive supplies as well, which typically means usage of large transport aircraft. Due to importance, vulnerability and obviousness of these air bases, they are typically situated far behind the front line. As a result, fighter aircraft have to traverse long distances to the combat zone, requiring tanker support to reach their targets, further increasing their logistics footprint.

For this reason, fighter aircraft has to be able to operate from FOBs (Forward Operating Bases). That way, fighters would be close to friendly ground troops, increasing the time spent in the combat zone, and thus reducing the size of the force necessary for the effect. These bases should be very small, holding no more than a few fighters each (ideally, a pair or a flight of four). Fighters and everything else present would be camouflaged with the use of multispectral camouflage nets, making finding them more difficult. Crews would live in tents, which would be camouflaged the same way. In the case some are discovered and attacked, wide dispersal of forces achieved in this way would limit damage compared to attack agaist conventional air bases. Due to necessarily small size of such bases, any fighters used from there have to have small logistics footprint, and ground forces present would also be small. All of this would result in very small logistics footprint of each base, as well as reduced footprint of the force as a whole. Small logistics footprint required would necessarily mean a light (5-7 metric tons empty) single-engined fighter design, however measures could be taken to reduce footprint of larger aircraft as well – specifically, dirt strip / open field capability.

Conclusion

As it can be seen, fighter design may change in major ways depending on its role and expected environment. However, most basic things are common for all fighters, and it would be a mistake to ignore them.

Further reading

https://defenseissues.net/2014/08/02/air-superiority-fighter-proposal-6/

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54 Responses to “Balancing a fighter design”

  1. Alex said

    Can’t we use a pair of IRST sensors as a rangefinder, like in the older designs before lasers? Of course the matching of the objects on the two images would be done by a computer algorithm now.

    • Picard578 said

      It is a good idea. But for best efficiency, said IRSTs should be on wingtips, which limits aperture size and thus range. This would create issues due to wings flexing in flight, meaning that relative positions of IRSTs will change. It should still allow enough accuracy for engagement, though. Other possibility is triangulation via datalinks between multiple fighters.

      • A'rhEngel said

        Or maybe using one big IRST for long range detection in the forward hemisphere and multiple IR MAWS for short to medium range spherical detection with the IR MAWS deployed in such a way that every possible direction is viewed by at least two IR MAWS or one IR MAWS and the IRST. Even if the IR MAWS don’t have the same detection range as the IRST, once the target has been detected by the IRST the computer can matched with the images from the MAWS and triangulate for range.
        If a heat sources is beyond the detection range of the MAWS it does not mean that the MAWS can’t “see” it just that the image is not clear enough to identify it. Once the IRST has confirmed the detection, the heat source detected by the MAWS that corresponds to the direction of the target identified by the IRST can be used, thru sensor fusion, for triangulating range.

        • Picard578 said

          Yes. One possible issue here is angular accuracy of MAWS, due to wider FoV required, but I guess it isn’t too bad…

        • A'rhEngel said

          According to Thales the angular accuracy of their DDM-NG MAWS installed on the Rafale is enough to allow DIRCMs to be aimed at incoming infrared missiles. Since DIRCM is basically a laser, that has to hit a fist sized target at about 10km to actually be effective, I suppose that if the angular accuracy of DDM-NG is enough to guarantee such a hit, it might be big enough that unidentified heat sources at 100 km might fall into an uncertainty range no bigger then the aircraft itself, then I suppose the binocular ranging error when working with the IRST might be no bigger then 1 km.
          Since a single DDM-NG sensor can cover a whole hemisphere by itself then for what I propose 4 would be more then enough, and would leave just a small sector directly bellow the aircraft covered by just one MAWS.

        • Picard578 said

          Sounds good.

  2. tdcoish said

    Picard, I’ve been thinking a bit about radar on a plane. I’m definitely with you in that it should be deleted from the interior of a plane. I’m not sure what your thoughts are on podded radar though. Personally, I think that it’s probably a great addition, since you can:

    -Have exactly the right ratio of planes with podded radars, to planes without. So experimentation may find that 100:1 with/without ratio is best, or it may find that 10:1 ratio is best.
    -You don’t ruin the weight and aerodynamics of every plane, the noses are sharp, the planes are light, and only one plane in a group (of size determined by experimentation), has to hang back and act as a sort of AWACS, suffering the weight and aerodynamic penalty.
    -You can have a much bigger radar, since you’re not limited by the interior of the plane
    -You can trivially swap between different types of radar, VHF for “stealth” planes, xBand for regular planes
    -You can trivially upgrade the radars for the plane, with absolutely zero redesign
    -When the radar breaks, you can just put a new one on and immediately fly away. Then you can fix the broken radar pod while the plane is flying
    -You’re not using a 747-esque plane for AWACS. (Seriously, what idiot thought that was a good idea?)

    Really this seems like a decision with absolutely zero drawbacks. Not seeing the downsides at all here versus radars in every plane, and I think that there’s a lot to be said for at least giving the pilots/aircrew the option of having a radar in their loadout that is tailoured specifically for their mission.

    • tdcoish said

      I just went back and looked at your Air Superiority Proposal – 6, and I see you included a pylon for radar, so I suppose that you’ve thought of this before.

    • Picard578 said

      I have included radar pod for FLX 6. That being said, internal radar does have a benefit since it can also act as a giant RWR, if properly designed. Larger aperture means far greater sensitivity, as well as better directional accuracy. But I’m not sure current radars have that option. That is why I was thinking about FLX 7 with radar included, but problem is time I will need to design it.

      • tdcoish said

        But don’t RWR’s have an enourmous advantage in detecting enemy radar? So as far as I’m aware they don’t need to be big, because of the combination of the inverse square law and the tiny percentage of radar that gets shot back at the exact right angle to the enemy radar.

        • Picard578 said

          True. But a lot also depends on technology used on both ends, as there are ways to make radar less detectable. In fact, LPI techniques were known and in use since World War II (frequency hopping).

  3. tdcoish said

    I also have a question with regards to Dynamic Instability. So I understand that regular planes for civilian use have stable designs. The only way I see this is in the wings, which are slightly angled upwards. This means that when the plane turns, the lowered wing is at an angle to generate more lift then the upper wing, which means that the plane wants to (gently) rock back to level flight. I looked at the picture of your FLX by Riley, and I can’t tell if it was just his impression, but it looks like the wings are actually pointing downwards at a slight angle. If so, is that to increase the instability, so that the plane rocks even harder into the turn?

    Secondly, I think I’m starting to understand why canards are much less stable than tail fins. When you point the nose up, then the tail fins are now generating lift as well, which pushes the tail upwards, and levels out the plane. Same is true for when you point the nose down, the tail is now generating reverse lift (not sure what the technical term is), which pushes the tail down, and levels out the plane. So if my understanding is correct, then that’s why fighters have nose canards (again I’m not entirely sure the technical terms), because then, when the nose is pointed upwards, the canards generate lift to accelerate the nose lift, which pushes the plane even harder upwards. Same is true for pointing the nose down, or side to side, all of which combines to make the plane more maneuverable in the air.

    Unfortunately I don’t know any aeronautical engineers, and Google has it’s limits for sure. If I got something wrong here I’d really like to know.

    • tdcoish said

      Anyway, to expand upon my last comment, if I indeed have figured this stuff out, and aren’t making any mistakes, then the weight of the plane is quite important to its stability, or rather, the weight distribution of the plane is very important to its stability. If we have a plane with the same aeronautical design, close-coupled canards, slightly down angled wings, then if we have more of the planes weight distribution in the nose, then it’s going to have worse maneuvering performance, and effectively more stability. Because the farther forward the weight of the plane, the less it can “whip” around its nose, because there’s less leverage over the wings. Now that I think about it, that must be part of the reason why it’s so important to have a skinny nose, the fatter the nose the more drag there is and therefore the more resistance there is to any turning (as well as general drag).

      So the first question I have is that am I correct in thinking that the nose of the plane should be as light as possible?
      Secondly, is there any limit to the benefit of dynamic instability? Basically, is there some optimal point, where after that point you lose out on something, or is it something that should be maximized, assuming that you’re not losing anything? I can imagine that wings pointing 45* downwards would probably kill your lift for instance, but I’m refering more to the weight distribution.

      • Picard578 said

        Yes, you are correct (I explained it in my last comment, before I saw this one). But nose width has little to do with it, in fact, if nose is of a lifting design, a wider nose may even improve maneuvering performance by adding lift ahead of C(g) (center of mass). But yes, the nose should be as light as possible.

        Wings pointing downwards has nothing to do with instability. And there is a limit – ability of Flight Control System to compensate. Because if it cannot compensate for aircraft’s instability, the aircraft crashes.

    • Picard578 said

      Aerodynamic stability is determined by relationship between the center of lift and center of mass. If you take a look at unstable aircraft, all of them have wings relatively forward, or else have canards. Either of these options moves center of lift forward. And since FLX has no radar, center of mass is slightly further back than with most other designs.

      What you are thinking of here is roll stability. Whereas former is determined by horizontal relationship between center of lift and center of mass, roll stability is determined by vertical relationship. And this depends on the vertical position of wings, and the angle of wings. Regarding the angle of wings, yes, the wings in FLX are pointing downwards, which increases roll instability, and thus improves roll onset and roll rate.

      RE: canards and tails, a lot depends on the aircraft instability. When pitching nose up, canards will create upforce and tail (or flaperons) downforce. But once angle-of-attack stabilizes, effect varies depending on whether aircraft is stable or unstable. If aircraft is stable, nose will have a natural pitch-down tendency. Countering this by canards will increase total lift and thus turn rate, and countering it by tail will decrease turn rate. On the other hand, unstable aircraft will have natural pitch-up tendency. In this case, canards will have to provide downforce, decreasing lift and turn rate, while tail or trailling edge control surfaces will have to provide upforce, increasing lift and turn rate.

      “Nose canard” is kind of like saying “animal horse”. Now, long-arm canard such as that on Eurofighter Typhoon is a control surface. It controls aircraft pitch, and what I wrote before fully applies to it. Close-coupled canard such as that on Dassault Rafale, Saab Gripen, Saab Viggen etc. is a lifting device, albeit Rafale’s and Gripen’s canard is also a control surface. This means that its main purpose is increasing lift in turn, whereas its utility as a control surface, while extant, is of secondary importance.

      You might want to take a look at these as well:
      http://photobucket.com/gallery/user/sampaix/media/cGF0aDovODBqYXMzLmpwZw==/?ref=

      https://defenseissues.net/2014/08/23/close-coupled-vs-long-arm-canard/
      https://defenseissues.net/2014/09/04/canard-aircraft-configurations/
      https://defenseissues.net/2015/11/01/dassault-rafale-vs-eurofighter-typhoon/
      https://defenseissues.net/2013/04/13/usefulness-of-thrust-vectoring/
      https://defenseissues.net/2014/08/02/air-superiority-fighter-proposal-6/

      • tdcoish said

        I’d read those before, with only semi-understanding of the aerodynamics argument. Thank you very much for these last two posts which clearly explain the concept.

  4. altandmain said

    An interesting question on the Command Fighter:

    – Would it look somewhat like the Su-27? Or perhaps a canard delta version of one?
    – Would it even be worth putting radar? A command fighter might be the ultimate platform to put a large IRST.

    This could be combined with the idea suggested before of using large airships.

    The large SU-27 like aircraft would have an even higher fuel fraction with no radar. I’ve suggested such an aircraft before.

    – About the length of an Su-27
    – Delta winged with canard
    – Some variants would be close coupled canards, while a dedicated bomber interceptor might be long arm canard
    – No radar, but large aperature for IRST
    – Multiple IRSTs, perhaps on the tips of the wing and perhaps a vertical stabilizer IRST
    – Long range missiles for taking on bombers
    – Could have multiple guns as well

    It would not have the transient performance of an FLX, but it would be fast and have longevity. The command variant would be a 2 seater, and a dedicated bomber interceptor would be 1 seater. The interceptor could double up for taking on enemy transports, tankers, maritime patrol aircraft, and other large targets, or it could be used as a tactical bomber (a much better bomber than an F-35 IMO).

    • Picard578 said

      You can’t put a too large IRST because of aerodynamic concerns. And radar does have its uses, however limited. And yes, it likely would look like Su-27.

      • A'rhEngel said

        Actually I think something the size of the Su-27 is big even for a command fighter.
        In my opinion a two seat Rafale would be the perfect command fighter, with some modification of course.
        First of all either switch to a swash-plate AESA radar as the Raven on the Gripen E/F or use multiple AESA panels for spherical coverage, it would be expensive but hey this is a command fighter one is not going to build a lot of them (maybe a maximum or 4 per squadron of 18+aircraft ?).
        Second: development of two types of conformal tanks similar in concept to the FAST packs of the F-15, that is tanks that allow not only the carriage of fuel but also add weapon hard-points. The latest version of the FAST packs if produced would allow the F-15 to carry 24 AMRAAM’s.
        One of the packs developed for our Super Rafale would be the air-to-air pack that each would add 6 conformal air-to-air missile hard-points for a total of 12 to compensate for the loss of two or four wing and body hard-points.
        The other pack would be the Strike Pack that would each have fuel and an enclosed weapon bay and would be shaped to reduce RCS. That would be for the penetrating bomber role that Altandmain suggested.
        Both types of packs would be carried conformal to the fuselage under the wings and would be dropable, so that once the fuel and weapons are used and the fighter is in danger it could jetison them for a boost of speed or maneuverability.
        The third modification I was thinking would be the envelopment of a wing tip hard-point or pod that would allow the carriage of at least 3 dog-fight missiles on each wing tips for a total of 6, that would be designed such that the baseline aerodynamic configuration of the Super-Rafale would be with the two pods fitted. This pods would be used both in air-to-air and strike missions so that even an Strike Super Rafale would have at least 6 dog-fight missiles.
        With this modifications I think a notional Super-Rafale would have range superior to a Su-27 type aircraft at half the weight and fuel consumption and thus cost of operation. Let’s not forget that the Su-27 is big not just because of range requirements but because Soviet Engineering had a hard time tminiaturizing the needed avionics and the engines where not as efficient as Western modern engines. For comparison the Su-57 (PAKFA) is smaller then the Su-27 while having the same subsonic range and supercruise range bigger then the range of the Su-27 at sea level and having two extra hard-points.

        • Picard578 said

          Rafale is capable of utilizing cheek radar arrays, not sure if AdlA has their development planned, though.

          Rafale’s conformal tanks are carried on its upper surface, so there is no need for weapons hardpoints as they do not negate the use of any hardpoints to begin with.

          That being said, dual missile rails, possibly combined with external fuel tank pylons, would be a good idea. That way, Rafale would be able to go into combat with a total of 5 fuel tanks and 16 missiles.

        • A'rhEngel said

          Well I was not thinking of the current Rafale but a notional future Super-Rafale.
          Frankly for me conformal tanks are an immature technology because they are not dropable. My opinion is that any external tank conformal or not should be dropable. Therefore the next avenue of research for conformal tanks should be conformal drop tanks. So the current fashion of adding humps to the F-16, Typhoon and Rafale is a technological dead-end. Let’s be serious to install those tanks one needs a crane. So a conformal tank is a permanent fixture in this case which takes away from the flexibility of the design. If the fighters for example needs to take-off quickly for a point-defense mission, close to the base where extra fuel is not needed, it would be forced to fight with the penalties associated with conformal tanks and none of the benefits.
          Compare this with the FAST packs of the F-15, that are placed under the wing and are as easy to load and unload as any ordnance. This gives the F-15 incredible flexibility. For example F-15 C/D which already have huge range normally operate without FAST packs. But when they operate from Iceland they usually carry them if it’s not a short mission. They also use them for ferry flights. F-15 E on the other hand fly almost always with the FAST packs. For the F-15 FAST packs are mission ordnance to be loaded as needed not a permanent fixture as the conformal tanks of F-16, Typhoon and Rafale.
          Also another interesting thing about the FAST packs of the F-15 is that they can reduce RCS if designed so, as in the Silent Eagle proposal.
          The only negative about the FAST packs is that they are not dropable.
          So that is why I was proposing new conformal tanks for the notional Super-Rafale not the crappy humps it’s supposed to get right now. And i was proposing two designs. A skinny streamlined one, with external weapons, that would not impede super-cruise, for air-combat, and a fat RCS reduction shaped one with internal weapons for strike mission. Both designs in my view should be dropable, therfore should be placed under the wing. Once the fuel and weapons are spent the pilot should have the option to jettison them. This might be necessary in both A-to-A and A-to-G mission for the fighter to enter a dogfight, either as part of a merge in Air-Superiority or to get rid of pursuers and escape for a strike mission.

        • Picard578 said

          Conformal tanks are mostly to increase range in ground attack missions without sacrificing hardpoints or causing too much induced drag, so they do not need to be droppable. Not exactly a dead end, but not an optimal solution either. They are not a permanent fixture, however, so it does not need to be used in point defense missions.

          F-15-style conformal tanks are superior in that they are easier to load, and IIRC may not even sacrifice hardpoints because they have hardpoints installed on them. But to my knowledge, even underside conformal tanks are not droppable like drop tanks are. They are not properly shaped for it, and even if separation mechanism could be designed, conformal tank risks flying straight back into the aircraft dropping it.

      • altandmain said

        I think the best option may be to build a family of fighters.

        Actually this “family” may very well resemble what the Su-27 family has become in some regards. Some would have radar, some would not.

  5. Alex said

    Since there is no radar in the nose, you can put the gun there like in the F-5 — https://en.wikipedia.org/wiki/File:Cannon_M39A2.png

    I’d propose that the better design is a Gast principle operated twin barrel cannon like the Gsh-23. It has much higher fire rate, simplicity compared to revolver types and reliability. You could chamber it in 27mm Mauser or any other round, the soviets used 30mm in the Su-25.

    • Picard578 said

      Yes, GSh-23 seems to be a good design, but muzzle velocity is too low.

      • A'rhEngel said

        Well that comes from the ammunition used 23x115mm which is derived from the 14.5x114mm round. That means it has only slightly more powder for twice the mass and therefore is under-powered. The round precedes the gun and the gun was probably designed based on the dimensions of the cartridge. There is no reason why it could not be redesigned. For comparison the other Soviet 23mm round is the 23x152mm round that was used by the Il-2. It has more the 200m/s more muzzle velocity. It’s hard to compare to western rounds because Western countries have not used 23mm rounds since WWII, but a re-chamber to 27mm might be a good idea. Or maybe why not try to go for 35mm or 40 mm? I do believe a 2 barreled Gast gun might be lighter then an equal caliber revolver gun because of using a simpler mechanism with less moving parts. And offers better heat management because of the 2 barrels.
        Another thought to consider: could a Gast-gun be built with more then 2 barrels?

  6. tdcoish said

    Picard,

    I’ve always thought that the concept of wingtip missiles was a little bit off. If the plane is designed around them, then you really should never have them leave the aircraft. And you should especially never have one be fired and the other stay put. What do you think about the concept of putting IRST on the wingtips instead? It seems to have a few benefits to me. First of all, it improves the aerodynamic qualities of the top of the nose and may slightly increase the pilots visibility, because there is no IRST there anymore. Secondly, it can provide you with binocular vision, which solves the biggest problem with IRST, range finding. Thirdly, on the back you can put additional IR MAWS or UV MAWS, which can supplement or possibly even replace the MAWS on the tail, essentially for free aerodynamically.

    • Picard578 said

      It is not so much wingtip missiles, but rather wingtip missile *rail* that has main impact on aerodynamics. Of course, adding or removing a missile will affect aerodynamics, but not so much that it will really matter.

      Full-sized IRST is way too large to fit on the wingtip. An IR MAWS may be a good idea for that, it doesn’t take much space, but issue here is that wings have to be elastic. This means flexing under aerodynamic pressures. This in turn means that you will not be able to do a good range estimate, or even direction estimate, without a (likely very expensive) system to compensate for the flexing.

      It is more obvious on aircraft with longer wings, but it is always there:


      • tdcoish said

        Ah. Thank you so much for this. That’s quite unfortunate though. Guess we’re stuck with the unaerodynamic nose IRST. Do you know how much drag that produces or is it quite minimal? Also, do you think that there may be a place for wingtip FLIR on a CAS plane? I just ask because building it into the airframe seems dangerous and stupid, considering that it will only last until it is fired upon once.

        • Picard578 said

          I don’t think it produces much drag. You will notice that aircraft that had no IRST still had an IRST added, typically in an assymetric configuration. That would have been impossible if drag was significant.

          IR sensors are actually quite difficult to jam, as you need to hit them with IR laser covering the entire frequency range. So I do not understand what you mean by “it will only last until it is fired upon once”.

        • tdcoish said

          I mean it will only last until the bullets it gets riddled by totally destroy it. I mean it’s basically a type of camera, so there’s no such thing as a bulletproof IR sensor. This isn’t such a problem with the fighter plane, just because I don’t envision nearly as many bullets getting fired into the things. Nothing to do with jamming at all. I figure that it’s probably a maintenance nightmare to fix a FLIR that breaks inside of the nose, much more so than simply replacing the FLIR on a wing. Also, the second FLIR on a CAS plane acts as redundancy. So for those reasons wingtip FLIR seems more appropriate, but it’s a small thing.

        • Picard578 said

          Frankly, I don’t think there is much need for IRST/FLIR on CAS aircraft at all. They typically fly very low, so at ranges you are looking at, you can use night vision googles, or maybe have HMD connected to IR MAWS so as to allow 360* day-night awareness for the pilot – possibly even through the hull. When FLIR/IRST is needed, just slap on a pod and that’s it.

        • tdcoish said

          Well my thinking was that, especially here in Canada, but really anywhere in the wintertime, anything hot is going to stick out like a sore thumb. Not strictly necessary, but could be very useful. That’s another reason though to have them on the wingtips, so you can replace them with something more appropriate for any mission.

          Having said that, you may well be right that, at low altitudes, an IR MAWS with 360* coverage would be good at picking up those things anyway.

  7. leroyjhunt said

    F-15 E on the other(a) paw tent-fly almost always with the FAST packs. No,It can’t be built with more than 2 barrels, but you can hold two separate cannons along each other(a), like in the IL-76 turret — <a href="http://imgproc.

  8. tdcoish said

    Picard, I’m thinking more and more that the USAF really needed to build an upgraded Strike Fighter. I know that the F-35 is called the Joint Strike Fighter, but I mean an actually good one. I wish I could find you the website now, but I read that the A-7 had a range on internal fuel of almost 5000km, and the Greeks would fly the things 8000km’s to America, albeit with fuel tanks. The A-7 was capable of pulling 4.3G’s sustained turning performance, as compared to the F-35’s 4.5G’s. I’m having trouble finding the climb rate but I bet the F-35 beats it there, since the thing had a T/W ratio of less than 0.45. Having said that, the plane could carry over 20,000lbs of ordinance, compared to the 18,900 lbs of the F-35.

    Where am I going with all of this? Well I think one of the problems with people who design vehicles, especially airplanes, is that they try to make them good at doing anything. The F-35 is a true Frankenstein’s Monster, but pretty much all modern fighters suffer for also being turned into an air strike platform. It can’t be all that hard to build a great modern, subsonic fighter plane. If you can build some cross between the A7 and A10 you’d have a hell of a plane on your hands, for doing dedicated air strikes and Heavy CAS. I’ll expand more upon this.

    • tdcoish said

      I’m starting to think that the hardest part of balancing a fighter design is just knowing that the hell you’re actually building in the first place. If I had to run down all the possible “fighter” archetypes it would be something like this:

      High altitude Interceptor- Used for intercepting bombers, flying behind enemy lines and destroying cargo planes, fuel tankers, AWACS.
      eg. Faster, non-stealth F22 with more fuel
      -Extremely fast, great range,

      True Fighter – Used for destroying or at least distracting enemy fighter planes.
      eg. F16 successor, or better Rafale
      -Fast, high speed maneuverability

      Strike Fighter – Executes called in Air Strikes (flying artillery). Best plane to hunt down enemy ships.
      eg. Successor to A7
      -Huge payload (for fighter), great range (for fighter), very maneuverable albeit underpowered.

      Destroyer (Heavy CAS) – Can somewhat patrol an area for the troops, but mostly gets called in. Also carries huge payload. Called in after enemy found, or where it’s extremely likely that concentrated forces will be.
      -Warthog with bigger gun, larger payload.

      CAS (main) – Fire support for infantry/tanks/artillery. Scouting on the battlefield itself.
      -Your ALX proposal (or mine possibly)

      Scout/FAC – Finding enemy forces, but not to be used in high threat areas. Used to scout flanks and wilderness areas.
      -Your FAC is great here

      The USAF has an annual budget of 110 billion, and the USN has an annual budget of 400 billion, of which some must be for planes. There is absolutely no reason that they don’t have all six of these specialist planes created, on top of additional utility planes such as the OV10 Bronco. Having said that, I think that you can do a 90% job combining this down into just three different types:

      1) Fighter/Interceptor
      -Your FLX is a very good example here but perhaps you’d sacrifice some maneuverability and size (make it bigger), for extra speed and range
      2) Strike Fighter/Destroyer
      -Build something very close to an A-10/A-7 cross. An armoured, more maneuverable A7 would be fantastic. Alternatively, a less maneuverable but much faster A10.
      3) CAS/Scout
      -Something like a cross between your ALX and OLX. I suggested building the ALX with turboprop engines and making it smaller and it would fit just perfect here.

      I say all this because I think that a country could do a pretty damn good job with just these 3 combat planes, but that you can build a much better Fighter/Interceptor and CAS/Scout plane if you focus on just doing those missions, instead of designing a plane to do all three of Fighter/Interceptor/Strikes and Destroyer/CAS/Scout. The fighter will be saddled with unnecessary avionics for air to ground, in addition to excess wing thickness and weight. The CAS plane with be unnecessarily large and fuel inefficient.

      Additionally, probably most importantly. Fighter planes should be single seat. CAS and FAC planes should be single seat. Strike/Destroyer planes should be double seat. So right there it sort of requires its own design anyway.

      I say all this to point out that balancing a fighter is something you have to do a lot less of if you’re the US, because you have so much money that you can get economies of scale with a whole bunch of specialized aircraft. Of course, the US is also the worlds leader in making ridiculously “multirole” aircraft that are crippled in their roles, but the principle remains.

      • Picard578 said

        Yep, that is definetly true. In fact, I had a mind to write something like that. Now, as to your points:

        1) FLX is a defensive design. Maneuverability and size are a must. Reason why I wanted high fuel fraction (0,4 at least, I achieved 0,44) is a) it was needed for supercruise requirement, and b) I wanted to achieve as long range in as small aircraft as possible, so as to allow it to carry out offensive missions as well.
        2) Strike fighter is expected to perform in air combat as well. So you would be looking at something like Panavia Tornado, Harrier or F-35. What you have described is not a strike fighter, but strike aircraft.
        3) Do turboprop engines provide enough thrust? And if they do, why are turbofan engines so widely used for CAS aircraft (A-10, Su-25)?

        I designed CAS and FAC aircraft to be twin-seat because they are expected to double in their missions. CAS aircraft is expected to perform FAC if air defences are too dangerous for prop FAC to do it, and FAC aircraft is expected to perform CAS mission in COIN situations. And my designs were not meant just for US, but for Europe as well.

        • tdcoish said

          1) Yeah the FLX is a little bit of a compromised design, which seems to be going for that 90% area between perfect Interceptor and perfect Fighter. I think that it’s a very intelligent design (on paper), which is absolutely right for many countries.

          2) As I expanded upon below, the strike fighter does do air superiority, although mostly against everything other than fighters. It’s the mop-up plane and can be outfitted as a command fighter. A modern, better, A7 is my idea.

          3) Well we’ve been over this. Big enough engines and definitely yes, especially at low altitudes and low speeds, but all of this depends on where you want to land on the (fuel efficiency/thrust) spectrum, with medium bypass turbofans providing clearly more thrust, although diminished at low speeds.

          All of these planes have some bleed over into the others, although there’s a bigger gap between my destroyer concept and the strike aircraft, with there essentially being two groups of three, Fighters(Interceptor, Fighter, Strike) and Attackers(Destroyer, CAS, Scout/FAC). My ideal solution for Canada would be, considering our budget, something like your FLX, but possibly with more range and speed sacrificing small amount of maneuverability (just cause it’s Canada), combined with my take on your ALX (turboprop engines, smaller overall size and payload), that would hopefully be an adequate solution in all three Attacker roles when called upon. Combined with not idiotically retiring the F18, and using it as a command/strike fighter, and I think that’s something approaching an 80% solution, provided enough of the planes are built. Other countries in different political, geographic, militarist, and financial situations would probably be extremely happy with your FLX, ALX, OLX combo, which I think is a pretty great place to start for all nations.

        • Picard578 said

          Agreed. My FLX/ALX/OLX mix is mostly for European defensive scenario, but it would work for other countries. For Canada specifically, I would mix FLX and F-15E, due to its size; FLX for local defense and F-15E for patrol and as a command fighter.

    • tdcoish said

      Anyway, to expand upon my A7, A10 cross. The main problem with the A10 is that the plane is frankly not very good at the scouting role. It’s far too fuel hungry to be used as a scout, and as I’ve mentioned previously, they never built enough of them in the first place. Those two things combine to make for a plane that rarely gets brought along “just in case”, and instead usually finds itself responding to an emergency.

      However, I think that’s totally fine, but if that’s how the plane is going to be used, then the plane needs to be designed a little differently. The US sorely misses the A7, or a plane in the style of the A7. It wasn’t a particularly great CAS plane, but the navy would have gotten tons of usage out of the things hunting down enemy ships, had there ever been a real war. Anyway, both of these planes are 50 years old at this point. This may be technically unfeasable, or simply impractical for some other reason, but I’m going to run this concept I have by you and see what you think.

      Take the A10, and install two higher power, lower bypass ratio engines in the thing. Improve the design so the whole thing is lighter, and use that extra weight savings to install a 35mm autocannon and increase the wing payload. The A10 currently has a maximum speed of 706 kmph, and a cruise speed of 560 kmph. With the increased power of the engines let’s say you have a plane that cruises at 800 kmph. I think you now have a great Strike/Destroyer hybrid aircraft to replace the A10, with more of an emphasis on the Destroyer part. Sure, this exacerbates the A10’s flaws, but, like I said below, not every plane needs to be perfect at doing everything.

      Alternatively, take the A7 and armour the thing against small arms fire. Increase the payload, and give it more than an M61 Vulcan 20mm cannon. Make the plane more maneuverable at low speeds. If you could do all this while keeping the range the same (or increasing it), you’ve got a fantastic Strike/Destroyer hybrid with a focus on the Strike part.

      I usually like to give more detailed and realistic proposals, but I don’t know how feasible it is to make an A10 that fast with the same basic airshape. Also, I’ve heard Pierre Sprey himself talk about how he thought the A10 could be made (much) smaller even back in the 70’s, but I don’t know for sure how much smaller we can make it.

      • Picard578 said

        Your “modified A-10” proposal would result in an A-10 that has greater TWR (and thus acceleration and climb rate), greater firepower, but less endurance than current A-10. It would perform well in your “destroyer” concept, but issue is that CAs fighters often need to loiter above the troops (look at A-10 missions in Middle East, they typically remain on station even after insurgents leave). And lower-bypass engines would damage that ability. It could supplement the A-10 very well, but it could never supplant (replace) it. A-7 proposal OTOH would be very good, but I have issue with it performing CAS missions (bad cockpit visibility due to cockpit design and high wing, issue with rearming the aircraft due to high wing, vulnerability due to single engine). It simply is not a CAS design.

        A-10 could have been made much smaller, that is what I did with my ALX proposal.

        https://defenseissues.net/2013/12/28/close-air-support-fighter-proposal-3/
        Length: 12,04 m (12,6 m with tail)
        Wingspan: 12,97 m
        Height: 3,2 m
        Empty weight: 6.500 kg
        Combat radius with 10 minute combat and 2 hour loiter: 603 km

        https://en.wikipedia.org/wiki/Fairchild_Republic_A-10_Thunderbolt_II
        Length: 53 ft 4 in (16.26 m)
        Wingspan: 57 ft 6 in (17.53 m)
        Height: 14 ft 8 in (4.47 m)
        Empty weight: 24,959 lb (11,321 kg)
        Combat radius: ** CAS mission: 250 nmi (288 mi, 460 km) at 1.88 hour loiter at 5,000 ft (1,500 m), 10 min combat

        I might have overstated ALXs combat radius somewhat, but other than that, it should be accurate.

        • tdcoish said

          Well I completely agree that my destroyer concept would have issues with persistence, but that’s why you build a bunch of more specialised planes. My idea for the USAF would be to build something very similar to your OLX, ALX, but also a plane the size of the current A10, but with a much larger cannon (maybe even the bofors 40mm or something), plus much increased payload, and the same or greater maneuverability. The entire point would be to call in the plane only when things are already bad on the ground, or when you have a good idea that things will soon get very bad on the ground. Something similar to the ALX would be the mainstay CAS of course, and I would also build enough of the things that there would always be some with the troops before even being needed. There are still going to be times when you can make fantastic use of the enourmous firepower of my Destroyer.

          As for the improved A7, I very much meant emphasis on the strike part. It’s CAS would consist of loading up with a bunch of CVR7’s and unloading them onto the (hopefully) correct area with a high altitude gun run to boot. Very much not something that you do near the troops on the ground, but of some value nevertheless. Not meant to replace an actual CAS plane in the slightest. The main benefit would in hunting for enemy ships, and in that role I think it could excel. Also, of course, it can perform air strikes with conventional weapons for the troops, which is somewhat overrated, but can be of some value regardless. Given numbers and pilot skill, the plane can defend itself just fine against enemy fighters, and can absolutely clean up against everything else that flies, so it’s very useful in air superiority as well. Finally, I envision this aircraft in the same role as the F18 Growler (btw, the F18 is a strike fighter realistically).

          So they’re very much different planes, and my point was just that the USAF doesn’t need to make these hard decisions as to which one it’s going to build. They have over 2500 fighter planes now and they constantly complain as to how few they have. The economy of scale exists to produce much more than the 6 different combat aircraft types I’ve listed here.

        • Picard578 said

          Yes, that would work.

  9. altandmain said

    Funny – the F35 now has 108 aircraft that won’t be combat capable at all:
    http://www.pogo.org/straus/issues/weapons/2017/21-billion-worth-of-f-35-concurrency-orphans.html

    I wonder if there will be more where that came from.

    • tdcoish said

      Yeah the F35 program is a total joke, but we already knew that. It’s just kind of frustrating that it’s such a financial boondoggle, that people get the impression that it’s a good airplane except that it’s too expensive. People are sometimes unable to understand that more money sometimes equals less product.

      • Picard578 said

        You also have to remember that humans are emotional, not rational, beings. Being a Croatian and not an American / British / French / Russian gives me a very different perspective. Many people believe that F-35 is good simply because it is “Made in USA”… same goes for Russians with PAK FA, French with Rafale etc. For my part, I don’t like any of them very much, but I do believe Rafale is the best of the bunch. But my personal favourite would be Gripen A with IRST and IR BVRAAM.

        • tdcoish said

          Yes, and as a Canadian I feel somewhat the same. It’s very hard for me to be objective when evaluating the F18, for example, because it’s what we’ve flown since the 80’s. Having said all that, I’ve also had reason to research objectively the fighter planes considered for the replacement, which lead me to your site.

          With regards to Canada, sometimes we must swallow our pride and accept that we don’t have the funds for developing planes ourselves. I don’t necessarily believe in that, and would love to build your FLX, ALX, and OLX, with or without some modifications, but that might not be possible. Having said all that, I think the simple solution of:

          1) Buy 250 Gripens
          2) Buy 750 Super Tocanos
          3) Keep old F18’s as strike fighters/command fighters
          (all numbers chosen superficially)

          … would be a 55% good enough solution. It’s very frustrating that this is such an easy, if not ideal, solution is well within the reach of our hideously corrupt politicians.

        • Picard578 said

          Yes, that would be a good option. It would in fact cover most important of CAF requirements: namely, air policing and COIN.

        • tdcoish said

          BTW my point was that if I struggle to be objective over the F18’s, then I can see how people aren’t objective over planes that their country designs and builds.

  10. tdcoish said

    Actually I’d be quite interested in hearing about your ideal composition of combat aircraft. I know that you don’t have necessarily all that much knowledge about the proper design of cargo aircraft, but I wonder, if you had the close to unlimited budget of the USAF, what would you build?

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