Japan’s X-2 “Shinshin” indigenous stealth jet makes first flight

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1. All the pictures I’ve seen of it show it with its landing gear deployed. Even in flight, those things are dangling beneath it. Is there any reason for this?

   • Safety…

     In case something went wrong and the aircraft had to immediately land.

   • Maybe for safety? If the landing gear is stowed away and there is a problem, it could be harder to lower it. Im not sure though, just guessing!

   • It’s very common for the first flight of a brand new aircraft design to leave the landing gear down. There are quite a few things that can go wrong on the first flight. Leaving the gear down eliminates some of those things. First flights usually concentrate on low speed handling characteristics, so retracting the gear often isn’t necessary.

   • Good question, but fairly common for first flight purposes…even Gulfstream biz jets make their first flights in this configuration.

2. >>
   Physics are the same for everyone, any design looking to minimise a radar return is going to look similar, i.e all fifth gen designs.
   >>

   To which the only possible responses are ‘stealth doesn’t scale’ and ‘death in the details’. The X-32 PWSC was all but a new jet so the nominal excuse was that the F-35 would look like the X-35 and was thus a production predictable design in terms of costs and risks.

   And indeed, the F-35 was virtually a clone of the X-35 OML. The fact that the X-35 had fuselage mounted landing gear meant that it -did not- have a weapons bay which made it really convenient to mount AMAD type auxilliaries without effecting CG from an engine which had to subsequently be pushed aft and down on the jet, with a big, fat, belly fairing, to add all the auxilliaries and -even then- the integrated power and cooling pump system overheated and needed to be redesigned, twice.

   And when the MLG legs were moved outboard, doubling their length in high tensile strength steel the weight tripled. Not just in the struts themselves but in the wingroot carry through which now must support a fuselage which torsionally flexes downwards like interlacing your fingers and flexing your shoulders before undertaking some difficult task. Every time the jet lands on a wider gear track.

   When the F-35 weapons bays went on the CDR production jet, the need to maintain SDLF module volume on the centerline moved their heavy weight A2G wells outboard. This added weight on the outer 20% of fuselage box frame, adding massive (2,000lb GBU-31) inertial loads in roll which complicated the wingroot carrythru even more (to the extent that the fuselage lap joints had to be redesigned something like 5 times).

   You also put a hole which ‘turned the corner’ on the fuselage box beams, further weakening the structure and adding even MORE weight to repath loads, as well as doors which were visible to RF in two axial planes as they opened (RCS and seal issues).

   Not knowing what the effect of the world’s hottest fighter core engine would be on composites in close proximity to these new weapons bays, everyone failed to understand the acoustic and thermal loads being applied to munitions carried near that engine or the performance and tactics effects they would have, especially at low level. Flapping your skirts to keep cool and staying under Mach .9 at all times, under 15,000ft does not make you a fighter.

   Finally, the stealth itself added weight and thermal issues which have made heavy impacts on performance and particularly on the need to make exotic allowances for fuel carriage.

   The F-35 radar is tiny which is going to effect tracking distance on other VLO targets, even if the APG-81 is GaNi.

   Now, let’s look at the X-2.

   First, it’s smaller than an F-16 while nominally being intended to replace the F-15 in an increasingly offensive, overwater, OCA/ASUW mission to challenge PLAAF/PLAN attempts to control first island chain gas fields like the Senkakus and to potentially interdict PLAN maritime commerce in local waters.

   Second, it’s got no weapons bays with all the F-35 transitional effects implied

   third, it’s designed around an assumption of 3D TVC to imply heightened pointing agility which is going to directly effect transverse as well as longitudinal loads, adding weight on the tail of the jet. Those paddle nozzles will have to go, in addition to massive drag and RFLO signature penalties, by essentially taking way 15-20% of length and providing a straight shot view down the burner tube, you have totally scragged your IR signature (which is increasingly going to dominate stealth design overall).

   Speaking of RFLO/IRLO, where stealth is a function of coating weight vs. square area of the airframe, if you take this to be a scaled technology demonstrator, having a 29ft wingspan (F-5E) on a 46ft fuselage (.63 ratio), scaled up to even F/A-18 size for fuel and bay volume, this equates to a 35ft wingspan (F-16) on a 56ft body. Take it to full F-18E scale 61ft long and you still have less than an 38ft wingspan. This is important because weight doesn’t scale, linearly, with area to begin with and it gets worse when you add stealth materials which tend to be very dense.

   What might work on a T-X trainer sized airframe volume, with lots of body lift, will not work on a true fighter because linear scaling of things like wing area will result in linear improvements in wingloading but alinear effects on both weight and drag.

   Ruling of this jet is /awful/. You don’t have to coke bottle anymore but they have taken inverse (vertical, like on the Hornet) ruling to an absurd abstraction with the front end of the jet too small to accomodate useful avionics volume and the back end looking like they tried to pour a gallon in a pint pot in terms of these XF5F core turbines. This makes no sense because, even if the folks at Ishikawajimi Harima have put ADVENT or better pressure ratios in a TFE1042 core and the carcass diameter of the engine installation is strictly triple cycle bypass ducting; the mass flow limits on those tiny intakes is not going to support the kinds of T/Wrs you need for a military engine. You will run out of gas or you will not have the airflow you need to feed the compressor section of a ‘30,000lbf’ class engine in a scaled-101 sized installational envelope.

   So why compromise so much of the designs supersonic ruling with a fat backend and needle nosed front when the radii that you’re operating at dictates a stealth+BVR approach to save on burner gas and prevent being forced into a close-in fight with a numerically superior Chinese force?

   IMO, this jet and the 350 million they have spent on it thus far, represents either a T-2 replacement as possible T-X partnering offer. Or/and a one-off systems hack with which to insert techint stolen or modified F-35 technology improvements (why they are going for FACO level industrial buyin for just 40 and not 150 Lightning IIs to replace both F-15J and F-2S), ‘if and when’ their true heavy weight, area defense intercept, fighter enters development.

   That jet is about as likely to look like an F-22 as it is a Sopwith Camel in that, though ‘the mission’ will remain the same, you will almost certainly see answers to the capability requirements that include high velocity jetstreams from am multicycle engine and either no or fold up level empennage using ICE system design points with integrated tiperons, SSDs, boundary control vectoring and of course advanced 3DTVC to replace most conventional maneuvering devices.

   By itself, this will pull 5,000lbs of 9G structure off the back end and perhaps another 5-7,000lbs of fuel weight off the wings _if_ the Japanese wisely avoid the ‘my fighter turns better/faster/tighter than yours!’ fetish by instead going with a ‘my 250KW SSL laser turret makes airframe turn rates largely passe`’ equivalents.

   Stealth is nice because it limits the number of people who can see you to shoot missiles. But if just one airframe does acquire and hands off through a netcentric datalink system, he or it can provide constant tracking updates to multiple dozens of other platforms in a shooter:illuminator/MFFC force construct.

   ONCE THAT HAPPENS you are back to defeating the arrows from all the archers. And that is where a laser weapon is going to replace, not just the gun and the dogfight but considerably alter the nature of the BVR engagement as it will kill the missiles themselves at perhaps 7-10km and IR weapons will be particularly vulnerable (due to their seeker aperture) to ‘hard dazzle’ photoplane damage to perhaps twice this distance.

   In essence, we are running hard upon an age in which jets size -can- shrink because they can no longer carry sufficient internal missiles to beat down combined LO + Laser defenses and in turn, the dogpile-not-dogfight approach of LCID hunting weapons. Drop 50 MALI out the back of a C-130 and send them _ahead of_ the ‘fighter sweep’ with the latter using their own, very large (15-20″), hyperspectral, optical sensors to replace radar in both cueing the hunting missiles (hounds before the horsemen) ahead and it’s own laser weapon defenses.

   You will still have some internalized weapons penalties to pay, inherent to engines powerful enough to drive high KVA generators and capacitor banks to power the laser weapon. And you will probably have 2-4 lightweight, multirole, missiles onboard. Ejected aft, in prepackaged tubes like torpedoes, which can strike specific targets of opportunity that might be worth the effort. But things like large internal weapons bays, huge tails and bubble canopies, all of which contribute to drag and lift at drag, will all be gone.

   Which is where I will close this comment with the note that ‘shin’ means core. And a ‘shin shin’ is slang for a self-actualized person. So if you think of this as a core technologies demonstrator, it probably doesn’t matter if it has a few features which are pointless for want of never being intended to appear on a production airframe so much as provide redundancy of flight safety in a high value systems testbed.

   But the days of fighting the way the videos show the X-2 doing, with rapid, spiraling, nose points to ‘get inside’ the enemy threat are so much an anachronism of a century old warfighter paradigm that if this jet looks /anything/ like a what a fighter in 2050 does, you might as well name it ‘The Quixote’ instead.

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