FLX vs F-35

Introduction

This article will compare a theoretical FLX concept with the F-35 JSF. Hence, it is more than just a comparison of different aircraft. Rather, it is a comparison of results of two different approaches. FLX is a thoroughbred air-superiority fighter, while the F-35 is a jack-of-all-trades (supposed to be; its design imperatives were in-theatre strike and battlefield interdiction). FLX uses an integrated design approach where each piece of technology used has very clear purpose within FLXs operational concept, while the F-35 is an exercise in cramming every possible piece of “high technology” into one airframe.

While FLX is designed for high-maneuverability in both beyond and within visual range scenarios, often-ignored fact is that F-35 was advertised as a highly-maneuverable dogfighter, before its obvious inability to actually achieve high maneuverability forced Lockheed Martin to change rhetorics. In matter of fact, BVR and WVR combat are extremely similar, only differences being engagement ranges, maneuvering speeds and amount of reliance on sensors – BVR platform has just as great need of maneuverability as a WVR one.

 

Impact on pilot’s skill

Most important factors in fighter design are ones that directly affect pilot: sortie rate / maintenance downtime, operating cost, user interface and reliability. Good enough pilot will compensate for aircraft’s weaknesses and focus on strengths, and even if aircraft is inferior across the board, he will be able to beat the opponent through tactics. How important training is was shown clearly in Vietnam: early on, USAFs F-4s achieved negative 2:1 exchange ratios against NVAF MiG-19 and MiG-21. Once USAF put some effort into pilot training, they started regularly achieving positive 2:1 exchange ratios. This is despite the fact that in dogfight, angles fighter (MiG) has no inherent advantage over the energy fighter (F-4) – or the opposite. In fact, MiGs had advantage in Vietnam due to smaller size and less smoky engines.

FLX can fly 2,7 hours each day. Fuel consumption is 1.276 kg/h cruise, 5.438 kg/h at maximum dry thrust and 17.812 kg/h afterburning. Direct operating cost per hour of flight is 4.600 USD. F-35 can fly one hour every two days. Fuel consumption is 2.721 kg/h cruise, 8.890 kg/h at maximum dry thrust and 39.000 kg/h with afterburner. Direct operating cost per hour of flight is 30.000 USD.

It is necessary for pilots to fly at least 30 hours per month. While FLX allows up to 80 hours per month in the air, F-35 allows meagre 15 hours per month, nowhere near the amount of time necessary. Even so, direct operating cost per month will be 368.000 USD for the FLX and 450.000 USD for the F-35. If FLX flies 30 hours per month, operating cost will be 138.000 USD, allowing three aircraft to be operated for price of a single F-35 while flying twice as much per aircraft. Combined with the fact that FLX pilots will only train for air-to-air combat, this will make them far more proficient in air-to-air than their F-35 counterparts.

 

Situational awareness

FLX has three full-sized dual-band IRST sensors positioned around the airframe. These are staring dual-band devices and provide complete spherical coverage. It also has 4 IR MAWS sensors plus 6 RWR sensors, all providing spherical coverage. All sensors listed can be used for targeting, and displaying data on pilot’s HMD. It also has a clear canopy providing 360* horizontal and 200* vertical visibility, including 16,5* over the nose, 3,5* over the tail and 30* over the sides, with a maximum of 50* over the side visibility.

F-35 has a single IRST sensor under the nose. It is a staring midwave sensor covering low frontal sector, and optimized for air-to-ground work; it is still able to detect low-flying afterburning aircraft at 160 km from the rear. Additionally, its IR missile warning system (DAS) can (?) be used as IRST. This system provides spherical coverage, with a caveat that it is short-ranged when compared to full-blown IRST systems. Lastly, it has radar; this however is primarily air-to-ground sensor and will typically stay offline during air-to-air combat to avoid providing the enemy with crucial data. It has a sunk, framed canopy providing 340* horizontal and 188,5* vertical visibility, including 16* over the nose, -7,5* over the tail and 26* over the sides, with a maximum of 40* over the side visibility.

Overall, FLX has advantage in situational awareness, both in beyond and within visual range situations (12% greater cockpit visibility). F-35 may have slight advantage in detection range with IRST (PIRATE can detect a fighter at 145 km from the rear, but FLXs Skyward should have higher detection range), but is significantly disadvantaged in sensor coverage. F-35 may have spherical coverage with DAS providing optical feed to the pilot, assuming that helmet issues are solved. However, pilots still prefer not to use the helmet, as that way they can see with far more clarity and depth perception than what helmet allows.

F-35 is supposed to act as a stealthy AWACS. But this role it cannot fulfill, as its single pilot will get overwhelmed with information – an information overload. It is a major problem which cannot be solved – if pilot is aware of the data being sent, then he cannot focus on piloting and will die due to not noticing a missile headed his way. On the other hand, if data dissemination is automatic, then other units in the air and on the ground will not be able to function properly due to overabundance of data, which will take time to sort out. Apparently, Western civilization simply cannot wrap its head around the fact that “more” is not necessarily “better” – even when it comes to information. Even with relatively basic information, ability to configure the HMD and cockpit displays to exact needs or preferences of the pilot would be a great thing.

 

Stealth

Stealth can be divided into several areas: visual, radar and IR. Visual stealth refers to how easy is to to see the aircraft with Mk.I eyeball. Radar stealth can refer to two things: aircraft’s radar cross section (RCS), and aircraft’s radar emissions (EMCON). IR stealth refers to aircraft’s IR signature.

In terms of visual signature, it is quite easy to see that the FLX is harder to detect.

FLX vs F-35

In terms of radar signature, things get a bit more complicated. F-35 is likely to use radar, which will allow FLX to detect its radar emissions a long way off, and target the F-35 solely through its radar emissions. FLX will have RCS of 0,65-1 m2 in armed configuration, while AN/APG-81 has 160 km range vs 1m2 target. This means that the F-35 will detect the FLX at 144-160 km. If FLX uses jamming, F-35 will be capable of attacking the FLX from 0-16 km with radar, 60-75 km with IRST, or 105-120 km without jamming. FLX will be able to attack the F-35 from distance of 125-330 km solely through RWR data, or 70-75 km with IRST, IRST initial detection range being 90-100 km. That being said, ability of both to attack the opponent will be limited by missile effective range (15-100 km for Meteor, 9-36 km for AIM-120D, 4-16 km for MICA).

While FLX is designed to rely on passive sensors (IRST and RWR) and F-35 is a radar-centric platform, F-35 does have an onboard IR sensors capable of detecting hostile aircraft. Its primary IR sensor is EOTS IRST. However, EOTS is not a “traditional” IRST but rather an inbuilt IR pod, optimized for ground attack. It has only single midwave channel, which gives it lower detection range at high altitude when compared to dual-band Skyward sensor of the FLX. At low altitude and in adverse weather conditions, this difference is significantly reduced. Skyward’s detection range advantage is further increased by the fact that it is electronically staring system with mechanically scanned head, while EOTS is electronically scanning system with staring head. This means that each Skyward’s element has far longer exposure time than each EOTS’s element, and it can be focused much like a telescope.

In terms of IR signature, there are several factors that should be noted. First, both aircraft are single-engined, but FLXs EJ230 only produces 7.348/10.478 kgf of thrust, compared to 12.700/19.512 kgf for the F135, leading to lower IR emissions from the engine for equivalent engine setting. FLX is also capable of supercruise, unlike F-35. This means two things; first, it will not be using as high percentage of maximum dry thrust during subsonic cruise, and second, it will not have to use afterburner anywhere as often. All things combined, engine IR emissions will be significantly lower for the FLX than they will be for the F-35. Second, FLX is both smaller and aerodynamically superior design. This reduces its IR signature due to the object being smaller, and due to lesser energy being required to move through the air. In particular, smaller wing span of the FLX means that F-35 will have 58% larger shock cone profile when supersonic, while lack of horizontal tail and higher wing sweep reduce wing drag. Both size and temperature are important: while at low altitude atmospheric absorption and clutter mean that it is easier to notice hotspots, at high altitude lack of both atmosphere and clutter means that target size and sensor’s resolution play important role as well.

 

Cruise performance

FLX can cruise at Mach 1,52 with 8 missiles or Mach 1,62 with 4 missiles. Its fuel reserve allows it 20 minute supercruise and 2 minute combat at 521 km from the base. Maximum combat radius on internal fuel is 1.218 km.

F-35 is supposed to supercruise for 150 nautic miles at Mach 1,2 with 4 missiles. 150 miles at 40.000 ft and Mach 1,2 would take 13,08 minutes. At test bench and full dry thrust, F135 consumes 11.089 kg per hour, while the F-35 has 8.280 kg of internal fuel. 2.417 kg theoretically spent for “supercruise” (real value would be less) is 29% of the F-35s onboard fuel. F-22 can cover a maximum of 0,04 miles per pound of fuel at 45.000 ft and Mach 1,5. Its combat radius is 400 nm with 100 nm supercruise; this means that it uses 5.000 lbs of fuel for supercruise and 8.600 lbs for subsonic cruise. As the F-22 has 18.000 lbs of internal fuel, 13.600 lbs of fuel would equalize 76% of the onboard fuel, with just supercruise requirement accounting for 28% of the onboard fuel. F-35 is clearly unable to supercruise, which is supported by three things. First, all supercruise aircraft had top speed of Mach 1,8-2,0, limited by engine pressure recovery limit and not by thrust-to-drag limit. Second, F-35s diverterless intake is unsuitable for supercruise. Third is the following quote:

“What we can do in our airplane is get above the Mach with afterburner, and once you get it going … you can definitely pull the throttle back quite a bit and still maintain supersonic, so technically you’re pretty much at very, very min[imum] afterburner while you’re cruising,” Griffiths said. “So it really does have very good acceleration capabilities up in the air.”

F-35s maximum combat radius is also lower than FLXs, at 1.082 km (a 12,5% difference), despite having almost twice as much internal fuel. This is most likely on the account of lower fuel fraction (43% vs 39%) and F-35s inefficient aerodynamics. This places F-35’s bases at the outer edge of evolved Scud ballistic missiles’ range while FLX is outside that range. Further, FLX can use dispersed basing and road/dirt strips to make location more difficult and reduce damage in case of the missile attack. F-35 is limited to using large air bases. Supercruising FLX can also use tanker support and/or supersonic external fuel tanks to significantly increase combat radius (FLX with 3 supersonic tanks has combat radius of 700 km at Mach 1,22, or 470 km at Mach 1,52 with no tanks). F-35 is limited to maximum cruise speed of Mach 0,95, which gets reduced to cca Mach 0,8 with external fuel tanks. If subsonic external tanks are used, FLX can achieve maximum combat radius of 1.855 km.

 

Maneuverability

FLXs turn rates should be 32,1 deg/s ITR and 24,1 deg/s STR. F-35A should have instantaneous turn rate of 26,6 deg/s and STR of 10,03 deg/s. Since two degrees per second turn rate difference allows pilot to dominate adversary in dogfight, it is clear that the F-35 is seriously outmatched in close combat. Aerodynamically clean configuration for both aircraft includes four air-to-air missiles.

FLX should be able to accelerate from Mach 0,8 to Mach 1,2 in 24 seconds, compared to 63 seconds for the F-35A. Its initial climb rate of 313 m/s is also superior to the F-35s 259 m/s; thus FLX will be able to outmaneuver the F-35 while forcing the F-35 to quickly loose energy. Roll onset rate will be higher for the FLX, due to smaller wing span and presence of both LERX and close coupled canards; F-35 only has chimes, and these cause adverse vortex interaction which leads to vortex bursting well forward of wing trailing edge; there is no aerodynamic support of outboard vortex flow that would be provided by full LERX. Even if bursting did not happen, vortices are drawn inwards due to suction, meaning that they have little to no effect on outboard wing control surfaces, unlike vortices produced by FLXs canard tips; this means that FLX will have far higher roll onset rate.

f35vortexuv4

That being said, the problem seems to have been solved. Vortex system will still have little to no effect on outboard surfaces.

F-35A_Hill_2013

Close-coupled delta-canard wing offers significantly higher maximum lift coefficient and positive trim lift on all control surfaces. Further, canards and wing control surfaces overlap in their functionality, unlike with horizontal tail configuration, leading to improved damage resistance. During level flight or sustained turn conditions, canards provide download while trailling edge control surfaces provide upload; F-35 only has tail to provide upload. Modern unstable canard-deltas (FLX included) will have canards provide no moment force during sustained turn conditions, thus reducing drag and improving lift-to-drag ratio; further, presence of canards has beneficial impact on wing L/D ratio during all turn conditions. When initiating a turn, canards will provide upload while trailling edge control surfaces and tail will provide download. When combined with canards’ longer moment arm, this results in higher turn onset and thus improved transient performance, which is crucial for dogfight.

(Note that the best way to escape either missile or gun shot is instantaneous turn in order to put the attacker at 3/9 o’clock followed by acceleration, and if necessary another turn. Sustained turns do not have much place in dogfight. In a multi-ship dogfight, no turn should be followed for more than 90 degrees).

Both FLX and F-35 will have good post-stall maneuverability (~110* maximum angle of attack, ~70-80* sustained angle of attack for the FLX and 110* maximum, ~60-70* sustained angle of attack for the F-35. FLXs numbers are likely to be higher than listed as they are based on aerodynamically somewhat inferior Gripen). However, while F-35 requires a chute for spin recovery, FLXs close-coupled canards will allow purely aerodynamic spin recovery. This is important since stall spin is the leading cause of maneuver-induced aircraft losses at 31%; post-stall maneuverability by itself has little use in combat. F-35s wing root vortices are also drawn inboard, causing loss of outboard wing control surfaces effectiveness at high angles of attack. Interference between vortices also causes bursting well before they reach wing trailing edge, let alone tail surfaces, leading to reduced tail effectiveness as well as increased vertical tail wear. FLX canard tip vortices meanwhile energize outer portion of the wing, allowing high controllability and good roll performance even at extreme angles of attack, while both canard root and LERX vortices energize inboard portion of the wing, increasing lift. Consequently, FLX will have superior nose authority at high angles of attack. Both FLX and F-35 will have large amounts of forward fuselage lift during level flight and maneuvers, with FLX fuselage lift being improved through “spillage” from canards as well as LERX. With both aircraft, vortices originating from nose will also improve lift.

F-35s 35* swept wing is optimized for subsonic and transonic maneuverability, whereas FLXs 50* swept wing focuses on transonic and supersonic maneuverability, while still retaining excellent subsonic performance thanks to integrated close-coupled canard design. F-35s lower wing sweep results in extended transonic region and much faster supersonic drag rise with Mach number.

During supersonic flight, aircraft will become more stable. FLXs close coupled canards will reduce pressure point shift with increased speed, allowing FLX to remain aerodynamically unstable at higher speeds than non-canard configuration would. Once aircraft does become stable, FLX will transition trim authority to canards. This means that while F-35s horizontal tail will have to provide download and subtract from lift, thus worsening L/D ratio, FLX will use canards to keep the nose up, which will lead to improved L/D ratio compared to canard-off configuration and thus increased maneuverability as well as improved cruise performance (cruise speed and efficiency).

 

Weapons

F-35s primary missiles are AIM-120 for beyond visual range engagement and AIM-9X for within visual range engagement. AIM-120D is a RF BVR missile with 180 km maximum aerodynamic range. It has 40 g maneuvering capability at Mach 4. AIM-9X is an IR missile with 26-42 km maximum aerodynamic range and 50 g maneuvering capability at Mach 2,7.

FLXs primary missiles are MICA IR for beyond visual range engagement and IRIS-T for within visual range engagement. MICA IR is an IR BVR missile with 80 km maximum aerodynamic range. It has 50 g maneuvering capability at Mach 4. IRIS-T is a WVR IR missile with 25 km maximum aerodynamic range and 60 g maneuvering capability at Mach 3. Additionally, it will be able to use Meteor as long-range BVR missile; it has 315 km range and 40 g maneuvering capability at Mach 4. Until Meteor is avaliable, AIM-120 can be used.

With standard loadout, F-35 has advantage in nominal missile range. However, its primary BVR missile – AIM-120 – is an active radar missile. Consequently, even if the F-35 does use its IRST for passive attack, missile will give itself away with its own radar, quite possibly long before enemy MAWS notices it. Once it does so, its limited maneuverability and usage of easily jammed or decoyed RF seeker head means that any enemy fighters will easily avoid it (even Pentagon is getting worried about that); historically, kills (especially BVR) were typically achieved when targets were not aware they were under attack. FLX itself, with its extreme maneuverability and disposable jammer loadout will have no problems evading it. AIM-9X is an IR missile with 26 km range; AIM-9X Block III with 42 km range was supposed to provide genuine BVR capability, but its development was cancelled.

FLXs MICA IR on the other hand uses an IIR seeker. This has two advantages. First, it is passive, which means that enemy gets no warning of an incoming missile until (and unless) his MAWS notices the missile. Second, IIR seekers are very hard to jam and nearly impossible to decoy, forcing enemy fighter to rely on maneuvers to evade it. MICA is also more maneuverable than AIM-120. If used against the F-35, F-35s own limited maneuverability will likely cause it to be a toast against MICA. It should also be noted that difference in missile range between F-35s AIM-120 and FLXs MICA will be smaller than cited for two reasons. First, FLX has 11.000 ft (~3.400 m) advantage in service ceilling. Second, it has Mach 0,57 cruise speed advantage even while carrying twice as many missiles. In WVR fight, IRIS-T is shorter-ranged but more maneuverable than the F-35s AIM-9X, and FLX can use AIM-9X if necessary. IRIS-T is also said to be capable of intercepting incoming missiles, but Pk is at best unclear. Both FLX with IRIS-T and F-35 with AIM-9X will be able to engage targets at their six o’clock.

FLX has standard onboard loadout of 6 IR BVRAAM, 2 IR WVRAAM and 5 gun bursts. This translates into 2,51 onboard kills. F-35 has standard onboard loadout of 4 RF BVRAAM and 2,6 gun bursts. This translates into 0,996 onboard kills. “Heavy” loadout for the FLX is 4 RF/AR BVRAAM, 8 IR BVRAAM, 2 IR WVRAAM and 5 gun bursts, translating into a total of 3,05 onboard kills. “Heavy” loadout for the F-35 is 8 RF BVRAAM, 2 IR WVRAAM and 2,6 gun bursts, translating into a total of 1,62 onboard kills. As it can be seen, in both cases FLX has significant advantage in number of onboard kills. In “heavy” configurations, FLX also has advantage of having up to three different types of BVR missiles, causing problems for the enemy trying to evade them and improving total salvo Pk. F-35 can use AIM-9X as a BVR missile in order to add IR seeker to the mix, but it still has no proper anti-radiation missile, and AIM-9X is shorter-ranged than MICA IR.

 

Numbers in the air

FLX allows up to 80 hours per month in the air, F-35 allows meagre 15 hours per month; direct operating cost per month will be 368.000 USD for the FLX and 450.000 USD for the F-35. If two FLXs are used, they will allow 98 hours per month for 450.800 USD versus 15 hours per month for 450.000 USD for the F-35, a 6,5:1 advantage. Even including indirect costs would be unlikely to bring FLXs price above 15.000 USD per hour per aircraft, compared to the F-35s likely price of 52.000 USD, a 3,5:1 advantage for the FLX.

If initial costs are compared, FLX costs 42 million USD vs 120 million USD at the very least for the F-35, giving it a 2,86:1 advantage or greater. Further, each FLX can sustain >=2,7 sorties per day, while F-35 can sustain one sortie every 2 days. Therefore, FLX can provide at least 15 sorties for each F-35 sortie flown. Further, FLX is designed for base-level maintenance while F-35 is designed for depot-level maintenance, significantly increasing F-35s logistical tail.

 

Response to attacks

While F-35 requires full-blown air bases to be kept in operation, FLX can be operated from road bases. F-35s ability to quickly respond to attacks is also limited by its lack of supercruise capability. Its maximum cruise speed at dry thrust is cca M 0,95; to achieve supersonic speed it needs afterburner, thus reducing supersonic endurance. At low afterburner, F-35 can maintain Mach 1,2 for 150 miles (241 km), and to achieve even that performance it can carry only 4 missiles in its weapons bay. FLX has supersonic cruise speed of M 1,52 with 8 missiles and can maintain it as long as it has fuel onboard, for a maximum of 470 km each way, + two minutes in full afterburner. With 4 missiles, FLX achieves M 1,62 with supersonic combat radius of 500 km.

 

Engagement kill chain performance

http://www.ausairpower.net/APA-NOTAM-05072010-1.html

Kill chain consists of following steps:

  • detect
    • detection capability
    • identification capability
  • engage
    • cruise speed
    • maximum speed / mach on entry
    • altitude on entry
    • lock on / firing solution range
    • missile seeker diversity
    • endgame countermeasures (inbuilt, towed, disposable; jammers, decoys, chaff, flares)
  • defeat the missile / disengage
    • airframe agility
    • sensors coverage
    • mach on egress / fuel reserves on afterburner
  • destroy
    • BVR missile seeker diversity
    • BVR missile agility
    • BVR missile warhead lethality
    • WVR missile agility
    • WVR missile warhead lethality
    • gun lethality

 

Detect

Detection range depends on target signatures and sensors used. As discussed before, F-35 will be able to detect the FLX from 144-160 km by using radar. However, radar is an active sensor. Signal has to be sent out, reflected from the target and received. Even assuming that target is a flat plate and that entirety of the signal reaches it, radar will get back 1/16th of the signal – at best. However, RCS comparison shows automobile to have an RCS of 100 m2 (likely from the side; from the front, 25-50 m2 value can be expected). As FLX, despite having frontal area of similar size to automobile, has RCS of 1 m2 or less when armed, it can be seen that the F-35s radar will receive at best 1/400th of the signal it has sent out. Even when aperture size difference between RWR and radar is accounted for, FLX will detect F-35s radar signal at two times the distance (290 km), possibly as much as several times farther (note that radar horizon at 10.000 m is at distance of 825 km). Since both fighters have extensive ESM capabilities, radar is not likely to be used.

If radar is not used, FLXs superior aerodynamics and smaller size will give it smaller IR signature. EJ230 engine also produces less thrust overall, and is cooler, than the F-35s F135 engine. FLX will be able to detect subsonic F-35 at 70-100 km, while F-35 will be able to detect subsonic FLX at <70-100 km, or supercruising FLX at <80-110 km. Since only reliable identification is visual (via IRST), FLX will have major advantage with its smaller physical size. Radar-based NCTR is very unreliable (30% identification reliability at best) and can be disabled by jamming or by target maneuvering. Because of this, 82% of the enemy aircraft engaged during Desert Storm had to be identified with help of AWACS, which will not be avaliable against a competent opponents as comlinks will be jammed, and AWACS aircraft will not survive for long in a proper war.

 

Engage

FLX has cruise speed of Mach 1,52 with full missile load of 8 missiles, or Mach 1,62 with 4 missiles. Top speed is Mach 2,0, limited by air intake design. F-35 has cruise speed of Mach 0,95 and top speed of Mach 1,67. While difference itself is not exactly small, F-35s top speed is drag-limited. This gives FLX excess power for any maneuvers. At the same time, FLX enjoys significant advantage in cruise speed, allowing it to more or less dictate terms of the engagement. FLXs cruise speed advantage when combined with good supersonic endurance will put the F-35 at constant threat of surprise bounces from the rear, and will allow the FLX to safely disengage from BVR combat whenever necessary while denying that same luxury to the F-35. FLX pilot will be able to simply run down the F-35, forcing it to spend fuel at full afterburner while the FLX itself stays in the military power or very low afterburner; he will have to expend or dump all but four missiles to do so, though, giving him parity in missile loadout with the F-35. Higher cruise speed and faster acceleration will allow the FLX to reach maximum speed far more quickly than the F-35 will be able to reach its own maximum speed. This is assuming that either fighter will actually have time to do so.

FLX will have service ceiling of 60.513 ft, which is significantly more than the F-35s service ceiling of 50.000 ft (though some data show the F-35 capable of 60.000 ft service ceiling without restrictions). Further, FLX is optimized for air superiority missions at between 30.000 and 50.000 ft, while F-35 is optimized for strike missions at 15.000 – 25.000 ft. This altitude advantage will give FLX a measure of superiority in air-to-air combat. First, combination of altitude and cruise speed / dash speed advantage will give FLX significant advantage in effective missile range while reducing F-35s missile range. Second, at closer ranges F-35s EOTS may loose sight of the FLX while FLX itself will be capable of keeping track of the F-35 with its underside IRST or by using MICA IR seeker head as a short-ranged IRST.

As shown before, FLX will be able to attack the F-35 from distance of 125-330 km solely through RWR data, or 68-76 km with IRST. If FLX uses jamming, F-35 will be capable of attacking the FLX from 0-2 km, or 105-120 km without jamming; using IRST will allow it to attack FLX from 60-80 km without being affected by jamming. However, FLX has combination of onboard and disposable jammers which will allow it to jam F-35s radar without much threat of AIM-120s home-on-jam mode. FLX also has advantage in missile seeker diversity: while F-35 uses only RF AIM-120 (possibly also Meteor in the future), FLX can use IR/RF MICA, IR ASRAAM and RF Meteor. All RF missiles in FLXs loadout should be modified to have anti-radiation mode or variants.

Both FLX and F-35 have a selection of RF and IR BVR missiles. However, while ASRAAM has maximum engagement range of 50 km, FLXs MICA IR has range of 80 km, giving FLX significant range advantage when using IR missiles (FLX can also use ASRAAM). This range advantage is increased even more by FLXs kinematic advantage over the F-35. Missile range from the rear is 1/4 of stated missile range, 100 knot speed advantage reduces missile range 5 to 25%, and effective range is 1/5 of aerodynamic range. With FLX at Mach 1,52 and F-35 at Mach 0,95 at 40.000 ft, speed difference is 327 knots; thus MICAs effective range will be 4,6 km, compared to 2,1 km for ASRAAM. With RF missiles, F-35 has AIM-120 with maximum engagement range of 180 km. This is significantly inferior to the 315 km range of MBDA Meteor (*even if FLX design started today, it would not enter service until 2019 at earliest, about the same time as the F-35; Meteor should be in service by the end of 2015). Further, Meteor’s ramjet propulsion gives it significant endgame kinematic advantage as well as 100 km range in straight line flight; both of these mean that it will have lethality advantage over the AIM-120. Both AIM-120 and Meteor are vulnerable to countermeasures, however, and F-35 will likely receive Meteor, somewhat reducing its disadvantage. Even then, in rear-end attacks FLXs Meteor will have 29 km effective range against F-35, while F-35s Meteor will achieve 21 km effective range against FLX.

 

Defeat the missile / disengage

Once warned of a missile launch, first reaction is to properly position the aircraft for evasion. At beyond visual range, it is oftentimes enough to turn the aircraft away from the missile. At shorter ranges (near-visual and visual range), pilot has to quickly position the missile to the aircraft’s 3 or 9 o’clock and then turn into the missile once close enough. Both of these require high instantaneous turn capability, as well as acceleration / climb to recover lost energy. FLX has instantaneous turn rate of 32,1 deg/s, sustained turn rate of 24,1 deg/s, acceleration time from M 0,8 to M 1,2 of 24 s and maximum climb rate of 312 m/s. F-35 has instantaneous turn rate of 26,6 deg/s, sustained turn rate of 10,3 deg/s at 15.000 ft, acceleration time from M 0,8 to M 1,2 of 63 s and maximum climb rate of 259 m/s. This means that FLX will have major advantage when evading missiles, which will be even more incresed due to FLX’s superior transient performance..

Both FLX and F-35 have 360* coverage with radar and missile warners, and are in that regard equivalent. However, F-35s primary sensors – radar and FLIR – only cover area in front of the aircraft (frontal 120* in case of radar). FLX has 3 IRST installations which allow it more-or-less complete spherical coverage. Consequently, when missiles are fired, F-35 has to keep its nose within 60* off the FLXs position, and doing so will reduce radar’s effective range due to the way AESA radars steer the beam; its IRST has similar issues, and DAS is visual-range-only sensor. Meanwhile, FLX can turn away from the F-35 while still keeping it within its IRST coverage, and if the F-35 uses radar, FLXs RWRs will also be able to keep track of the F-35 no matter the FLXs own orientation. This will significantly reduce F-35s own missile range, while presenting the F-35 pilot with an issue of wether to pursue the FLX and risk getting shot in the face with MICA or Meteor, or to evade the missile, losing track of the FLX in the process. (Note that all Western fighters will face the same dilemma when using radar. Only exceptions to this are Gripen NG and AESA-equipped Typhoon, as they will be able to place FLX at 9/3 o’clock while still keeping track of the FLX. This ignores effect of jamming on radar. IRST-equipped fighters may be able to do same with IRST, but of Western fighters, only Rafale, Typhoon and upcoming Gripen NG have proper IRST installation. FLX will still have advantage as it can keep track of target while placing it at 4-5 / 7-8 o’clock; engine emissions will likely prevent it from keeping track of target at direct 6 o’clock).

Fuel reserves for afterburner are also important. Assuming that both aircraft have 40% of the fuel avaliable for maneuvers, FLX will have enough fuel for 5,74 minutes of maximum afterburner, while F-35 will have enough fuel for 5,41 minutes of maximum afterburner. However, FLX has thrust-to-weight ratio of 1,22 at combat weight, compared to 1,074 for the F-35. Combined with superior aerodynamics, it will allow the FLX to get more mileage out of its fuel than the F-35. For more exact comparison I will assume 360* corner-speed sustained turn (or, rather, four 90* turns) followed by acceleration equivalent in time to M 0,8 – 1,2 acceleration. FLX will use 14,93 seconds of maximum afterburner for turn and 24 seconds of maximum afterburner for acceleration, leading to 39 seconds of maximum afterburner and a total of 8,83 maneuvers. F-35 will use 33,33 seconds of maximum afterburner for turn and 63 seconds of maximum afterburner for acceleration. This gives 96 seconds of maximum afterburner and a total of 3,37 maneuvers. If 90* instantaneous turns are used, FLX will need maybe 35 seconds of maximum afterburner, for a total of 9,26 maneuvers. F-35 will need cca 77 seconds of maximum afterburner, for a total of 4,2 maneuvers. If 10.000 meter climb equivalent is used after turns, FLX will use a total of 32,05 seconds of climb for a total of 46,98 seconds and 7,33 maneuvers; F-35 will use a total of 38,61 seconds of climb for a total of 71,94 seconds and 4,51 maneuvers. As it can be seen, FLX has significantly higher combat endurance despite similar overall fuel fraction and lower internal fuel load; even having full missile load of 8 missiles as opposed to the 4-missile clean configuration will not significantly degrade the FLXs advantage over the F-35. (Note here that this is based on sea-level figures; at 30.000 ft, actual thrust and fuel consumption will be closer to 1/3rd of those used, which will extend endurance. However, relative figures should stay similar. If anything, FLXs advantage should increase with higher altitude.).

In terms of countermeasures, FLX has chaff, flares, disposable RF jammers / decoys and internal DRFM jammer. F-35 has chaff and flares; it could also theoretically carry disposable jammers but has no internal jammer installed. That being said, F-35s low radar crossection makes usage of onboard jammer less beneficial than for the FLX, and in some cases counterproductive. DRFM jammer that the FLX uses is more-or-less immune to home-on-jam mode, and this vulnerability is completely eliminated by presence of disposable jammers. F-35 will likely have disposable RF decoys, which would give it an option to use jammers, as well as provide immunity to home-on-jam weapons. It can use its radar for jamming, but it only covers 120* forward cone and to do so it has to sacrifice frequency agility, making it vulnerable to anti-radiation missiles. Due to the F-35s RCS reduction making work easier for whatever RF countermeasures are present, I will consider countermeasures to be similarly effective in RF band.

 

Destroy

In terms of agility, AIM-120D and Meteor can both pull 40 g at Mach 4, ASRAAM can pull 50 g at Mach 3 and MICA IR can pull 50 g at Mach 4. This means that maximum turn rate is 18,54 deg/s for AIM-120 and Meteor, 30,9 deg/s for ASRAAM and 23,2 deg/s for MICA IR. Comparing this to respective aircraft turn rates (37,4 deg/s ITR for FLX and 26,6 deg/s ITR for F-35), it can be seen that the FLX has a good chance of evading any of the missiles listed. F-35 on the other hand has a good chance of outmaneuvering AIM-120, Meteor and maybe MICA IR, but may be in trouble if shot at by ASRAAM (missile needs to at least match aircraft’s turn rate, and in some cases have twice as high turn rate, in order to hit).

AIM-120D has warhead weight of 23 kg, compared to 12 kg for MICA and 10 kg for ASRAAM. Consequently, lack of agility is somewhat compensated for by larger warhead weight; still, even assuming a perfectly cylindrical propagation pattern, AIM-120D has 1,5 times as large lethal radius as ASRAAM while latter has 1,67 times as high turn rate. AIM-120D also has 1,4 times as large lethal radius as MICA while MICA has 25% better turn rate.

When it comes to WVR missiles, FLX carries IRIS-T while F-35 carries no WVR missiles as they have to be mounted on external hardpoints; UK version may be capable of carrying ASRAAM in internal bays. IRIS-T can pull 60 g at Mach 3, for 37,07 deg/s ITR, which the F-35 does not have a good chance of evading. On the other hand, 30,9 deg/s ITR of ASRAAM is inferior to the FLXs instantaneous turn rate. IRIS-T has warhead weight of 11,4 kg compared to ASRAAMs 10 kg, meaning that it is also more lethal on top of superior maneuverability.

If both aircraft are flying at Mach 0,9, FLXs 11 g turning capability will give it a turn rate of 22,67 deg/s compared to 18,55 deg/s for 9 g limited F-35. Thus FLX will be capable of defeating AIM-120D and Meteor, while F-35 will not be capable of regularly defeating any of the missiles within their no-escape zones, barring less-than-ideal launch parameters for missiles.

In terms of gun lethality, FLX uses GIAT 30 revolver cannon while F-35 uses GAU-22/A rotary gun. GIAT-30 fires 275 g projectile with 17,5% HEI content (~48 g) at 1.025 m/s muzzle velocity. GAU-22/A fires 184 g projectile with 16,7% HEI content (~31 g) at 1.040 m/s muzzle velocity. Further, GIAT-30 projectiles have crossectional density of 38,9 g/cm2 compared to 37,48 g/cm2 for GAU-22, leading to slightly slower loss of speed. Combination of these factors gives GIAT 30 significantly higher per-projectile effectiveness. Further, F-35 has to open up gun trap doors to use the gun, which adds 0,5 second delay. Even if gun doors are opened beforehand, GIAT 30 will fire 19 projectiles in first 0,5 seconds, compared to 16 projectiles for GAU-22/A. This gives total throw weight of 5,23 kg for GIAT 30, with 0,91 kg of HEI. GAU-22 has total throw weight of 2,94 kg with 0,49 kg of HEI. As it can be seen, GIAT 30 is significantly more lethal than GAU-22/A.

 

Ground survivability

Ground survivability includes possibility of camouflage and ability to operate from road bases. Latter includes STOL capability, wingspan limits, fuel consumption and ease of maintenance considerations. Wingspan should not be greater than 8,74 meters.

FLX can take off in 357 meters (rolling takeoff) and land in 245 meters. Wingspan is 8,5 meters. Fuel consumption is 1.222 kg/h cruise, 5.438 kg/h at maximum dry thrust and 17.812 kg/h afterburning.

F-35A requires 2.400 m runway for safe operations, which indicates 1.200 meter takeoff requirement. F-35B can take off in 173 meters (with 2 JDAM, 2 AMRAAM and fuel to fly 450 nm; rolling takeoff) and land vertically; this performance likely requires jump ramp. Wingspan is 10,7 meters for the F-35A and B variants. Fuel consumption is 2.721 kg/h cruise, 8.890 kg/h at maximum dry thrust and 39.000 kg/h with afterburner.

As it can be seen, there is significant difference in aircraft on-ground survivability in FLXs favor. FLX also requires far smaller maintenance support and far less fuel for operations, leading to reduced logistical footprint.

 

Conclusion

As it can be seen, FLX is significantly superior in air-to-air combat when compared to the F-35. Only way for the F-35 to survive is to avoid engaging FLX – at any distance. On the flip side, FLX is also completely useless for air-to-ground missions, while the F-35 is at least capable of carrying out SEAD/DEAD missions (both can carry out reconnaissance missions). This article does prove that one cannot put air-to-air missiles on a bomber and call it a fighter. Despite typical rhetoric surrounding the F-35, enemy does get a vote.

 

Notes

NOTE: tracking range is 80% of detection range, electronic acquisition 10-30 s, 78% reduction in range due to jamming (For Vostok E Russians claim it can find a F117 out to 380 km, however in a jammed enviorment this number can degrade to 72 km. This gives reduction of 81%, that is range in jammed environment is 19% of range in unjammed environment).

F-35 will detect the FLX at 144-160 km with radar

Acquisition will start at 115-128 km without jamming and will take 10 seconds

Acquisition will start at 22-24 km with jamming and will take 30 seconds

Mach 1,52 + Mach 0,95 = Mach 2,47 minimum closing speed = 728,403 m/s at 40.000 ft

Mach 2,0 + Mach 1,67 = Mach 3,67 maximum closing speed = 1082,283 m/s at 40.000 ft

Attack range without jamming = 104-121 km

Attack range with jamming = 0-2 km

F-35 will detect subsonic FLX at 60 km and supercruising FLX at 65 km with IRST

Acquisition will start at 48 / 52 km and will take 5 seconds

Mach 0,95 + Mach 0,95 = Mach 1,9 closing speed = 560,32 m/s at 40.000 ft

Mach 1,52 + Mach 0,95 = Mach 2,47 closing speed = 728,403 m/s at 40.000 ft

Attack range (FLX subsonic) = 45 km

Attack range (FLX supercruising) = 61 km

FLX firing solution with RWR: 140-340 km

Acquisition will start at 140-340 km and will take 15 seconds

Mach 1,52 + Mach 0,95 = Mach 2,47 minimum closing speed = 728,403 m/s at 40.000 ft

Mach 2,0 + Mach 1,67 = Mach 3,67 maximum closing speed = 1082,283 m/s at 40.000 ft

Attack range (both at cruise speeds): 130-330 km

Attack range (both at top speeds): 124-324 km

FLX will detect subsonic F-35 at 90-100 km with IRST

Acquisition will start at 72-80 km and will take 5 seconds

Mach 1,52 + Mach 0,95 = Mach 2,47 minimum closing speed = 728,403 m/s at 40.000 ft

Mach 2,0 + Mach 1,67 = Mach 3,67 maximum closing speed = 1082,283 m/s at 40.000 ft

Attack range (both at cruise speeds): 68-76 km

 

Further reading

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

https://defenseissues.wordpress.com/2012/10/07/f-35-analysis/

https://defenseissues.wordpress.com/2015/02/01/fighter-aircraft-gun-comparision/

https://defenseissues.wordpress.com/2014/12/06/fighter-aircraft-engine-comparision/

http://web.archive.org/web/20141127200736/http://www.mach-flyg.com/utg80/80jas_uc.html

http://hotair.com/archives/2014/12/04/dont-panic-but-pentagon-now-things-russia-can-jam-american-air-to-air-missiles/

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33 thoughts on “FLX vs F-35

  1. It seems that Rafale defeats the argument that a good air-to-air fighter cannot be a good air-to-ground bomber, Isn’t it?

  2. Excellent article (at least based on my own limited understanding of these things). A few questions, if I may.

    Could you please explain this statement a bit more:

    “Both size and temperature are important: while at low altitude atmospheric absorption and clutter mean that it is easier to notice hotspots, at high altitude lack of both atmosphere and clutter means that target size and sensor’s resolution play important role as well.”

    I would have thought that at higher altitudes, it would be easier to detect a plane using IRST (colder surrounding air providing a greater contrast with the plane’s temperature; fewer clouds)?

    Can you envisage an air-to-air situation where you would fit a radar onto the FLX? What about a “mothership” with radar and datalink to the other aircraft? Or would a UAV or AWACS be better for this?

    • “I would have thought that at higher altitudes, it would be easier to detect a plane using IRST (colder surrounding air providing a greater contrast with the plane’s temperature; fewer clouds)?”

      It is. But at high altitude atmospheric absorption is so low that eliminating hotspots won’ change detection range too much.

      “Can you envisage an air-to-air situation where you would fit a radar onto the FLX? What about a “mothership” with radar and datalink to the other aircraft? Or would a UAV or AWACS be better for this?”

      Stormy weather, bomber interception.

      Datalink is there, and I have included radar pod as a loadout option.

  3. The problem is that the real mission of the F-35 is to make Lockheed rich.

    An FLX fighter cannot do that – unless the profit margins are high per fighter and the volume high.

  4. “FLX is also completely useless for air-to-ground missions, while the F-35 is at least capable of carrying out SEAD/DEAD missions (both can carry out reconnaissance missions)”

    I still think that there is absolutely no reason, not even training, why FLX can’t carry out SEAD/DEAD missions. One dose not use ground cover in SEAD/DEAD missions, on the contrary one must make oneself as visible as possible to trick a SAM battery to open radar and shoot. DEAD/SEAD is very similar for a pilot to a BVR engagement. But that’s just my opinion. I guess we’ll have to wait for the FLX to be built and tested before we solve this little conundrum, which in my language will happen when horses celebrate Easter, 😀 .

  5. Glad to see another post (I admit that I was hoping for FLX proposal 7), but I want to address on some things I disagreed with.

    “In terms of visual signature, it is quite easy to see that the FLX is harder to detect.”
    To a degree, but the size difference between fighters is not notable enough. Eyesight, experience, weather, terrain, cockpit visibility and even canopy reflections of the sun are more important. That said, I agree that the FLX would have an advantage in visual spotting, but that is due to better cockpit visibility, and not smaller size.

    “AWACS aircraft will not survive for long in a proper war.”
    Not sure about this one, half agree because of missiles like the R-37 and Meteor, but by the same token, AWACS will be very far from the combat zone. Defensive anti-missile missiles also seem like they should be in development (even though I have not heard anything about such things), perhaps something like the Pye Wacket?

    “FLX cost per operating hour of $4,600; unit cost of $42,000,000; 37,46 deg/s ITR and 27,84 deg/s STR; F-35’s radar acquisition will start at 22-24 km with jamming and will take 30 seconds.”
    I very curious to see where you got these figures from.

    “Radar vs RWR detection distance.”
    Does not take into account the fact that LPI radar spreads its energy over multiple frequencies that the radar knows, and the RWR does not. I agree about AIM-120 seeker issue though.

    “F-35’s Radar acquisition time without jamming.”
    Admittedly a PR video, but it still shows an acquisition time of about 5 seconds in a jam-free environment (not my toast, then! An attempt at humor…)

    Also, the ‘incriminating’ report War is Boring dug up is about testing the F-35’s control laws at low speeds. The F-35 was not fighting to win, so using the report to say the the F-35 in a proper dogfight will loose against an F-16 with droptanks is not a verifiable conclusion.
    http://aviationweek.com/site-files/aviationweek.com/files/uploads/2015/06/F-35%20High%20AoA%20Maneuvers.pdf

    • Have you read the report and especially the pilots scanting conclusions? The first phrase of the report says ” The test was designed to stress the high AoA control laws during operationally representative maneuvers utilizing elevated AoAs and aggressive stick/pedal inputs. “. The operative words here are “operationally representative maneuvers” i.e. maneuvers that would actually be used in combat not just simple test maneuvers. That’s why they didn’t use a test pilot but a an active with experience in flying Basic Fighter Manuvers in 3 different aircraft similar to the F-35 i.e. multi-role with bias to AtG missions (F-15E, F-16 and F-18F) . He has the training and experience to know what are those “operationally representative maneuvers”. He’s very neutral about the whole thing, concludes that the control laws can be fixed but that the aircraft still is at an energy disadvantage against the F-16, and is very skeptical if fixing the control laws would actually improve turning all that much, seeing as the F-35 would have to be at a very high AoA to have better turning rates then the F-16 and at that high AoA it loose energy very fast, which has nothing to do with control laws but with the actual aircraft. He is also very critical about the vaunted helmet and the way it inhibits the pilot from actually turning his head, which leaves the high-off-boresight capability of the F-35 as theoretical.
      Also war is boring didn’t dig up anything, they simply quoted for the most part Aviation Week which published the report first-hand.

    • “To a degree, but the size difference between fighters is not notable enough.”

      I’d say it is from front and maybe side.

      “Not sure about this one, half agree because of missiles like the R-37 and Meteor, but by the same token, AWACS will be very far from the combat zone.”

      It is not only about that. AWACS have to have huge-ass runways to operate from, and these are some of the first things that will get attacked in an all-out war. Huge immobile areas aren’t exactly hard targets even for ballistic missiles.

      “I very curious to see where you got these figures from.”

      See the FLX proposal.

      “Does not take into account the fact that LPI radar spreads its energy over multiple frequencies that the radar knows, and the RWR does not.”

      In Western radars, all these frequencies are in X-band. Further, radar gets less than 1% of the signal that actually reaches the target.

      “Also, the ‘incriminating’ report War is Boring dug up is about testing the F-35’s control laws at low speeds. The F-35 was not fighting to win, so using the report to say the the F-35 in a proper dogfight will loose against an F-16 with droptanks is not a verifiable conclusion.”

      Actually, F-35 was fighting to win. It is the best way to check how aircraft will perform in actual combat, after all.

    • “I’d say it is from front and maybe side.”
      Well, purely in terms of comparison, I’d agree, but I still think it is a relatively small factor versus the others I listed in acquiring a target visually.

      “In Western radars, all these frequencies are in X-band. Further, radar gets less than 1% of the signal that actually reaches the target.”
      While you’re correct about the root power and distance, the key to LPI radars is not the generic function of EM projection and reflection, at least not solely, but more in that it is modulated, pulsed, or lobbed in such a manner that it confuses the RWR to either not detect it (as RWR’s need to filter out a ton of background EM energy) or to misidentify it. An RWR does not signal for every piece of EM radiation that hits it, it instead looks for a pattern, then attempts to identify the pattern based on the computers stored memory of that modulation. AESA/LPI radars send a receive a wide range of modulations and with high computing power can weave a series of modulations into a full picture. Furthermore, they also have excellent power control, allowing them to fluctuate power on different frequencies based on that specific frequencies strengths/limitations, further reducing potential detection. Still, there is no guarantee, and RWR design is advancing as well, as proven by this thesis https://calhoun.nps.edu/bitstream/handle/10945/2541/06sep_denk.pdf?sequence=1

      “See the FLX proposal.”
      Fair enough, I am still wondering about the 30 second acquisition time with jamming, though.

      “Actually, F-35 was fighting to win. It is the best way to check how aircraft will perform in actual combat, after all.”
      After reading the report objectives more closely, I will agree that the F-35 was fighting, and not just testing. Still, I think Axe went too far with his accusations. The report was certainly a bad blow to the F-35’s reputation, but I would not call it incriminating. The F-35 has the benefit of being new, which brings 2 justifications; the pilot flying the F-16 was much more experienced with his aircraft than the pilot flying the F-35, and the control laws are not fully optimized. An incriminating report would be if the result was the same, but the F-35 was one in operational use and it was flown by a pilot from an operational F-35 squadron.

      (Not a full response to everything as I’m a bit strapped for time)

      • “While you’re correct about the root power and distance, the key to LPI radars is not the generic function of EM projection and reflection, at least not solely, but more in that it is modulated, pulsed, or lobbed in such a manner that it confuses the RWR to either not detect it (as RWR’s need to filter out a ton of background EM energy) or to misidentify it.”

        Modern RWRs remember and analyze signals. Techniques you mentioned are nothing new either, they have existed for a long time, and RWRs are designed to deal with them.

        “Fair enough, I am still wondering about the 30 second acquisition time with jamming, though.”

        That’s just a rough estimate, it could be more or less depending on conditions. Basically, I assumed proportional effects.

        “the pilot flying the F-16 was much more experienced with his aircraft than the pilot flying the F-35, and the control laws are not fully optimized.”

        That is true. But keep in mind that F-16 in tests had two external fuel tanks (albeit empty). This easily compensates for control laws, and F-35 revealed many deficiencies that cannot be fixed or explained by pilot experience and control laws. Inadequate transient performance may be explained by control laws, but inadequate E-M performance is entirely result of aircraft’s basic design.

  6. ” Still, there is no guarantee, and RWR design is advancing as well, as proven by this thesis https://calhoun.nps.edu/bitstream/handle/10945/2541/06sep_denk.pdf?sequence=1
    One point I’d like to make regarding what you said above is that the way Radar producers talk about LPI, RWR producers talk about High Probability of Intercept, take for example this brochure of the RWRs produced by SAAB and used on the Gripen NG and by PIcard in his FLX proposal. http://saab.com/globalassets/commercial/air/electronic-warfare/self-protection-systems/idas-integrated-das/pdf-downloads/idas-cidas-product-sheet.pdf it repeats the phrase High Probability of Intercept several times when referring to RWRs. The point is that LPI techniques have been known and used since the 80s. And from the 80s the same techniques where used in reverse to identify radars. It’s highly unlikely that any breakthrough in sensors will not be countered in a few short months by sensor detectors manufacturers. In fact the task of building HPI RWR is a lot more simple then building LPI radars. LPI radars need advanced encryption-decryption algorithms to first send out a signal and then identify their own return and extract information from it. They practically have to do the job of an RWR in addition to sending out the signal. An RWR is simpler at the most simple case it needs just to “listen” and identify the direction from which “radar pulses” come from. Identifying is not the main task just recognizing that there is a radar in the vicinity and where it might be, and for this the decryption part is not necessary just sensitivity to pick-up a certain wavelength and processing to recognize that there might be a radar in a direction if “radar pulses” keep coming from that direction.

    • I agree with what you said, however, I noticed that this seems a bit bad for the FLX.

      “Identifying is not the main task just recognizing that there is a radar in the vicinity and where it might be, and for this the decryption part is not necessary just sensitivity to pick-up a certain wavelength and processing to recognize that there might be a radar in a direction if “radar pulses” keep coming from that direction.”

      One of the things that the FLX is supposed to be able to do is use its RWR to identify targets “…with Meteor being used in beyond radar range engagements with RWR providing the IFF.”
      https://defenseissues.wordpress.com/2014/08/02/air-superiority-fighter-proposal-6/

      • I was giving a minimum of what an RWR should do to improve situational awareness. In a sensor fused environment you don’t use just one rely on anyone sensor as it happens in a Radar biased fighter, but use information from all of them. RWR is the longest ranged and at minimum it will let the pilot know that there is an idiot out there buying into the marketing notion that a man with a flashlight is invisible at night just because he is painted black and the flashlight switching through the spectrum of color O_o (what basically Lockheed is trying to sell) and it will give a pretty accurate positioning of where that idiot is. From there on the computer will do the rest, either the radar is transmitting enough and it has been encountered before and is found in the database and the RWR alone allows for identification or the Radar is unknown is logged in the database and identified through IRST. Anyway in future encounters the Radar will be known. Also whether the Radar is identified or not has no bearing on whether the DRFM jammer can spoof it. DRFM works with the received signal, it copies it and then emits it in a way which fools the radar, all it needs to work is enough time to get a big enough sample to copy the signal. And if detection is achieved at 200+km there will be minutes, before the two aircraft reach missile range, plenty of time in which data can be gathered.

  7. Noticed something else;

    “F-35s top speed is drag-limited.”

    No it’s not. It’s top speed is limited to dynamic pressure at low altitudes (just like every other modern fighter), and it’s top speed at altitude is theoretically limited to around mach 2.0 due to intake design. It’s yet to be tested (to my knowledge) above 1.6 for no other reason than it is impractical. It’s never going to use it in combat (no actual dogfight ever has, with the exception of where one fighter runs itself out of fuel being chased), and we already know unlike the F-22 it’s never going to be setting records, so they just haven’t.

    Technically speaking both aircraft are drag limited anyway; above Mach 2.0 both lose airflow to their engines, losing a massive amount of power, leaving them sitting at their top speed where power and drag become equal. It could be said that without the drag limiting them, they could still accelerate a bit more.

    Why are you comparing the F-35’s current maximum tested speed, to the FLX’s theoretical top speed. Why don’t we use the F-35’s theoretical top speed?

    • “and it’s top speed at altitude is theoretically limited to around mach 2.0 due to intake design. It’s yet to be tested (to my knowledge) above 1.6 for no other reason than it is impractical.”

      Air intake design limit is Mach 2,0. F-35 has only ever achieved a maximum of Mach 1,67. And Mach 2,0 is far from being impractical for testing, seeing as how F-35 is assumed to take over air-to-air duties in addition to air-to-ground ones. It is true that it is not very likely to be achieved in combat, but there is always that “but when”. And seeing as main reason for impracticality of such speeds is fuel consumption, and that F-35 has high fuel fraction (higher than any other Western fighter), there is even less reason not to test it at that speed when compared to Gripen, Typhoon or F-22.

      “Why are you comparing the F-35’s current maximum tested speed, to the FLX’s theoretical top speed. Why don’t we use the F-35’s theoretical top speed?”

      Because unlike F-35, FLX should be capable of achieving its theoretical top speed.

    • The thing is, the Mach 2.0 intake is not the bottleneck.

      The draggy fuselage will assure that barring some major engine upgrades, the F-35 will never go to Mach 2.0. If you assume major engine upgrades for the F-35, you’d want contemporary engine tech for the FLX too.

      For most of its time in the air, the F-35 will be a subsonic aircraft. That is different than say, the FLX, which has been designed for the get-go to spend a very large part of its time in supercruise. In that regard, it is like the Concorde, or a few specialized designs like the SR71, the Mig-31, and a few one-offs. Most aircraft are not like that, even supersonic ones. They only briefly light up to supersonic for a smaller percentage of their lives.

    • Either way, this has been flawed from the very beginning as we’re comparing a theoretical concept to a working prototype approaching production. Lockheed certainly didn’t expect the F-35 program to be that much more expensive than the F-22 program, but in the end it did. The Russians also did not envision that the LaGG-3 would not be able to use the engine it was designed for, and at this point it did in the end, and suffered for it initially. The Russians also did not expect the PAK FA to have flameouts and generally be undesirable enough for India to withdraw. Setbacks occur all the time, and the FLX will not be an exception. The F-35 at least had experienced design flaws that weren’t expected.

      For the stealth section, what is the specific composite material the FLX will use?

      • The FLX if you’ve read Picard’s proposal is to keep it as simple as one can. Simpler = less room for flaws. He’s also made about 6 revisions so far addressing issues (earlier versions were simply not realistic).

        I’m sure there will be some flaws (and were a program like this to be undertaken, perhaps even a test aircraft or two lost), but because it’s more about application of existing technology, I don’t think there will be problems along the lines of what the F-35 or F-22 experienced.

        There won’t be radar stealth coating, by the way.

        • I’m not decided on wether to use RAM or not, but even if they are used, it will be RAM paint similar to that used on Rafale, and not inbuilt RAM coating as on F-22 / F-35. This means that it can be applied as needed, and does not lead to increase in basic maintenance requirements as is the case with F-22 and F-35.

          (Note: Rafale uses light-gray RAM paint, so it is just a standard paint job any aircraft would undergo, nothing special. It is more expensive than standard paint, though).

      • “Either way, this has been flawed from the very beginning as we’re comparing a theoretical concept to a working prototype approaching production.”

        As I have pointed out in the very beginning of the article…
        >>Rather, it is a comparison of results of two different approaches. FLX is a thoroughbred air-superiority fighter, while the F-35 is a jack-of-all-trades (supposed to be; its design imperatives were in-theatre strike and battlefield interdiction). FLX uses an integrated design approach where each piece of technology used has very clear purpose within FLXs operational concept, while the F-35 is an exercise in cramming every possible piece of “high technology” into one airframe.<<

        In other words, it is not just comparison of aircraft, but of design concepts as well.

        "Setbacks occur all the time, and the FLX will not be an exception. The F-35 at least had experienced design flaws that weren’t expected."

        Agreed. But difference is one of magnitude. Gripen – fighter that is most similar to FLX in concept and purpose – experienced relatively few setbacks. And FLX will not experience many of these if ever produced, as it is a single-role fighter, and design processes have advanced in the meantime. Especially FCS design knowledge is more advanced today, and it was precisely FCS that was a major problem during Gripen development.

        "For the stealth section, what is the specific composite material the FLX will use?"

        I imagined mostly identical composition to Rafale, which is to say canard and wing leading edges would be titanium, LERX would be kevlar. Remaining airframe would be mostly carbon fiber composites, though tip of the nose could be kevlar or titanium as well (depending on which material has the best heat resistence, I'm not going to look it up now).

        Note that lack of radar alone is enough to reduce RCS, as nose can be made of more stealthy materials, and will not be porous to certain frequencies.

  8. Also, you say this,
    “DRFM jammer that the FLX uses is more-or-less immune to home-on-jam mode, and this vulnerability is completely eliminated by presence of disposable jammers. F-35 will likely have disposable RF decoys, which would give it an option to use jammers, as well as provide immunity to home-on-jam weapons. It can use its radar for jamming, but it only covers 120* forward cone and to do so it has to sacrifice frequency agility, making it vulnerable to anti-radiation missiles.”

    You consider the F-35’s radar emissions which ‘sacrifice frequency agility’ vulnerable to anti-radiation missiles, so by the converse, the F-35’s radar in its frequency agile mode is not vulnerable to anti radiation missiles. Therefore, why would the F-35 ever not use its frequency agility?

    Also you say that the FLX’s DRFM jammer is immune to home-on-jam mode, but the F-35’s radar in jamming mode is not. You are imposing a double standard on the F-35.

    • “You consider the F-35’s radar emissions which ‘sacrifice frequency agility’ vulnerable to anti-radiation missiles, so by the converse, the F-35’s radar in its frequency agile mode is not vulnerable to anti radiation missiles. Therefore, why would the F-35 ever not use its frequency agility?”

      Because its radar is the only inherent jammer it has, and to jam the enemy radar it has to sacrifice frequency hopping ability. And frequency agility making it invulnerable to anti-radiation missiles is theoretical anyway, I simply decided to give the F-35 benefit of doubt here, as missiles have less processing power and smaller antennae than aircraft.

      “Also you say that the FLX’s DRFM jammer is immune to home-on-jam mode, but the F-35’s radar in jamming mode is not. You are imposing a double standard on the F-35.”

      There is no double standard once you know how it works. DRFM jammer has absolutely nothing to do with classical “barrage” jammers and similar types, which are indeed vulnerable to home-on-jam mode. What it does is to generate false returns which then radar processes, thus inducing a wide miss. F-35s radar, AFAIK, does not work on DRFM principle, instead trying to brute-force jam the enemy radar.

      But main point there was that FLX uses *disposable* DRFM jammers. So even if the above is proven wrong (by advances in missile signal processing or similar), missile will still be chasing a false target.

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