The X-32B was _not_ inferior to the X-35B for the following reasons:

1. Neither of the X-32 prototypes were built with production quality materials. Lack of autolayup looms meant their experimental shops had to hand-lay the thermoplastic composite skins which led to problems with differential heating in the autoclave which bubbled up ridges along the panel overlays. Buying an autowinder for an experimental prototype (i.e. paying for tooling, twice) was not affordable and thus, after multiple failures, the jet’s wing skins were redone in a thermoset composite which was 20% heavier. Add to this that the X-32 used ‘unibody’ techniques by which the wing skins were mechanically fastened to the airframe and you have major problems with the design weight tolerances as well as fabrication and assembly using things like longer screws on the thicker skins (and we are talking about 1,500 of them so it’s not a minor thing).

2. The X-32 didn’t meet other specs which the USN, as they often do to sabotage particular designs they don’t like, changed, halfway through the prototype manufacturing process. The original specs were within the capabilities of the X-32, even as _both_ specs for WOD and control power were beyond those of the X-35C, a fact which, in hindsight is obvious (I like to brag that I saw it ahead of time as one of the earliest critics of the JSF) in the design of the Lockheed prototype without such things as a working weapons bay or full length landing gears, mounted in the wingroots.

These were NOT engineering impossibilities which required ‘advanced technology’ to model or create. Rather they were explicit weight savings and manufacturing simplification approaches which allowed the X-35A/B and C to avoid such issues as the four-times-fixed wingroot lap joints whose later integration with particularly the STOVL model’s roll posts ended up costing the jet, not just so much weight in the PWSC variant as to be functionally non-CDR passable, but also the entire concept of easy manufacture using quickmate joints between pre-built subassemblies.

The point here being that the Boeing Preferred Weapons System Concept design would have had production quality skins, directly bonded to the structure, and a cropped-swept, supercritical wing design which would have traded about 1/3rd of the delta’s total area for a lighter, deeper, tighter, airfoil without as much wetted area but with far more fuel space as well as a slightly longer span and more lowspeed lift enhancement droops on the TE to solve approach speed and adverse sink rate/attitude problems behind the boat.

All of which would have made the short-span STOVL jet more than adequately able to meet it’s direct thrust STOVL requirements as it would have been half the wingspan.

i.e. The F-35 is what it is because the X-35 was a façade built around a fraud which included NONE of the operational engineering features that would have made the jet unable to pass even it’s X-jet evaluation phase, particularly the STOVL metrics, had they been suitably ‘productionized’ (as indeed they were on the preceeding YF-22). The F-32 was what it was because the Feds decided to change the specs to make it fail (and even then it was a close run thing with BOTH companies ‘passing’ minimum threshold requirements to prove their concepts…).

3. The X-32 had massive amounts of spare power. To support STOVL, the F119-PW-614 engine had an ENORMOUS fan on it. Even bigger than that which went on the eventual F135 to try and make up for the piggish qualities of the Lockheed aircraft. This resulted in up and away subsonic performance that was closer to the F-22 (admittedly IRT vs. Burner) than the F-16, as a function of subsonic acceleration and instantaneous vs. sustained turn. The F119-PW-611 was indeed a 28,000lbf/43,000lbf engine with just enough thrust on the front post to look pretty in STOVL. But the F119-PW-614 was a 33,000lbf/54,000lbf engine which absolutely blew the socks off the sexier X-35 where it counted as a turn and burn EM platform.

The trade however was fuel consumption and weight/balance issues. STOVL on the X-32 put the engine at a midpoint like an Airacobra which meant an overly long jetpipe, rather like you see on F-86s or MiG-15s. This was useless dead weight behind the CG in the design which, combined with the dual instead of quadpost, direct thrust, STOVL (very weak pitch control nozzle/liftscreen/roll-ducts) meant that the aircraft was not as stable in the hover. Yet that massive VL thrust requirement had to be there, leaving the jet’s TSFCs sucking down JP like a drunk locked overnight in a distillery as a function of stochimetrics necessary to keep sufficient rpms on the core to torque the spools on that big fan. Fan thrust which was actually pretty useless in the cruise part of the envelope as the jet approached transonics (this is the case with every turbofan and is nothing new, pilots of the then-new F-14 complained that the TF30 engines with almost 1,500lbf more thrust than the J79s they were used to on the Phantom were in fact ‘weak kneed’ as they crossed the .9 Mach threshold).

CONCLUSION:
If common sense rather than aesthetic sensibilities had prevailed, two readily identifiable conclusions would have been reached on the X-Plane contest:

A. The economics of ‘one winner’ political greed were utterly incompatible with national needs as the proper sustainment of the industrial base as _competitive_ sellers of modern fighters to the services. Particularly the USAF which had a huge requirement to replace the F-16 fleet could as easily have bought different airframes as engines when that requirement further spilled over into the F-15 and A-10 mission areas with drastically different performance requirements to the Viper followon.

Lack of competition has led to the total corruption of the F-35 acquisition process, from the dropping of the ‘unnecessary’ redundant engine to the failure to hold to the rigors of the law (Nunn McCurdy, the F-35 is _not_ ‘absolutely necessary’ to the modern defense posture, there are multiple alternative options) and even to the honesty with which other, fill force and Congressionally compliant, unmanned programs were actively sabotaged to remove them from consideration as JSF replacements (J-UCAS the ‘too expensive’ program which the USAF cancelled on the eve of the GWOT because it was a perfect match to COIN CAS loitering flight in SWA, something which the F-35 is not).

B. Neither jet was production representative.
The Boeing PWSC design would have been entirely competitive with the STOVL and a likely overmatch to the CTOL and CVTOL requirements with a new flying configuration and production level composites. The Lockheed JSF is as you now see it. Three different airplanes masquerading under the same name, each with sufficiently different design metrics to sabotage the other in terms of acceptable weight bloat vs. structural and weapons carriage restrictions, each stealing engineering design time from the others, greatly prolonging the delay before service due to LM’s simple inability (say: greed as the refusal to pay for and train up, despite record profits) to provide adequate engineering support to each individual airframe as it’s own unique development pathway. Things like the weapons bay, relocation of AMAD auxiliaries, wingroot support and avionics integration all suffered because the X-jet was designed without these gallon-in-pint-pot features included.

PWSC would have made these differences obvious and given Boeing the clear edge as the simpler design (it truly is one airplane, despite having different wingspans and a strap-on STOVL module) with better mass-manufacturing production experience base as well as Boeing’s HUGE overall engineering base.

Whether the JSF, as a subsonic, <550nm, strike fighter that is more F-117 than F-16/18 is what this country needs is another question. But it was a fool’s errand to choose such a large production commitment based on preliminary design constructs which were neither production representative for configuration nor anywhere’s near (materials, avionics, structures) complete in their supporting systems development. CBO and GAO both warned of this, starting as early as 1997, stating that concurrency was an risk that was not simply overarching but largely undefined as the jets detail design itself was incomplete before about 2002-2003.

Finally, a question in trade: Does anyone have any imagery of the proposed F-32 targeting FLIR? I have been told it was in an extendible fairing on the fuselage bottom, rather like that of the F-106 IRST but would like to know if any engineering drawings were made up or if the FLIR thimble that is sometimes seen in early photos of the 737 AFL is production representative? I am after pictures.

Thanks- Lop Eared Galoot.

The A-10 and Su-25 frogfoot are great planes but I have three competing designs somewhere in my mind 😀 which I wish this esteemed forum to weigh on. The basic parameters are:

You lost me somewhere between ‘A-10 and great airplanes’…

The A-10 came out of the A/X program efforts which were specifically an attempt by the USAF to undermine the AAFSS AH-56 Cheyenne and thus keep ‘deep CAS’ which is to say BAI/OBAS out of the hands of the Army (they’d already destroyed the effort to weaponize the OV-1 Mohawk).

As such, it was little more than a dumb bomb truck with limited survivability and weather penetration capabilities suitable for the ‘best days’ (65-68) in SEA. Before the SA-7 came south. Once that happened, the A-10 was little more than a fast Skyraider and would have been butchered, even in CAVU (keeping in mind that 3 months in Vietnam you can’t fly anything without blind letdown capabilities because of the monsoons and the VC moved at night with something like 12,000 trucks and 2,500 miles of roadways).

When we moved to Europe after leaving that wonderful region to it’s denizens, the A-10 was -not- upgraded to include such basics as low altitude radalt and terrain attitude avoidance, INS, autopilot, moving map or even TISL (the first 2 years). It had lousy cockpit integration with no UFC and a HUD was little more than an ironsight. All this in weather conditions which, in winter, make the B Maverick all but useless (the seeker contrast ‘assured target lock’ for the vidicon overlaps the gun _rmin_) and makes acquisition of targets from low level all but impossible without a FAC/TACP spot marking. D Maverick was nice but the LAU-88 was not and we didn’t get it until 1986, after ‘The Window Of Vulnerability’ was two years shut.

The jet doesn’t operate well at altitude, having always been short of thrust trust with lousy spool up times and a sharp power curve that leaves it positively gutless over 12,000ft and with a further big fat conical camber wing that rides the stall margin anywhere above about 15K. With the LAU-88 on the jet, drag was terrible and you could not make disengagement turns before crossing into the zip gun engagement envelope while the option to popup slow to a gunbunt and then apply power to hold energy coming off wasn’t an option because of spool up lag. Pilots for awhile were running around full throttle with the boards part open and then snapping them closed to bring power on the jet. Needless to say, this burned out the cores on the TF34 and greatly fatigued the wings to the point where over half the jets were in need of Hog Up/CUPID type work similar to the early F-16A/C aircraft before DS with less than 10 years on them. They retired most of them to serve as parts donors instead.

The A-10 was a natural for replacing the OA-37 and OV-10 in the FFAC mission and as a night intruder followon to the B-57 but desperately needed to have the mission suite and backseater that the N/AW brought with it. The USAF didn’t like the competition with the completely worthless LANTIRN system and so axed what was a cheap and functional pairing of the WX-50 (weather radar) and AAR-42 FLIR with Ferranti LRMTS for about 2 million per plane. On it’s own, in daylight, in Europe, the A-10 was utterly worthless, not least because the FOLs were all within about 50 miles of the front and as DS showed (without the wonderful German road net, in the middle of a desert) that’s about 3hrs before the T-72s are running over your Nikes.

1. Has to be single engined as part of a wider military-industrial plan.
2. Rugged, STOL platform
3. Low cost, cheap, easy to mass produce.
4. Has to run either on diesel or gasoline

Turbines are natural ‘multifuel’ engines simply because they run so hot. AvKer is little more than top grade diesel and while JP-8 has a few additives for accidental ignition suppression and all-altitude performance, any jet will run on virtually any grade of Jet-A1 or better. The turbine in the M-1 can burn gasoline, diesel and avker with the simple flick of a switch (and hourly cleaning of the filters). The problem with turbines is that they don’t scale well and have very narrow operating bands for maximum efficiency (which is high, around 70% burn rates due to the incredible compression as fuel:air mixing). What this means is you have to have basic minimum airflow for a given lbst equivalency and your operating range is from roughly 65-70% to 85-90% or IRT with only incremental differences in fuel burn as fuel requirements.

Which is why, if you want to get best median performance on Mach .7 or below ‘CAS’ airframe, you put a 3,500lbst turbine on it and then use a takeoff shaft to drive a big housefan like the P-3 (or the SABA). Problems still abound however because the blades are now chopping so much air at such high RPMs that any flow distortion (as with a pusher engine installation catching boundary crud from a fuselage or wing), combined with significant G force due to maneuvering, can warp and then break the propeller drive system which, at best, causes the engine to run like a washing machine full of blue jeans and at worst breaks the blades off themselves. Ninety percent of the problems with the Do-335 were do either to lack of cooling flow to the rear engine causing overheats and engine fires or to the damn prop losing it’s pitch synch and overspeeding right off the airplane.

In a CAS environment with a trike I would add that you would be looking at some considerable potential for both ground strike on rough fields and catching garbage thrown up by the nose gear.

True ‘diesel’ engines are most likely rotaries and are selected purely for their high compression state and low vibration for a given engine installation weight class. This makes them ideal for long loiter, high altitude, drone aircraft (cough, Predator Rotax 912/914) where you don’t need or want a highly torqued P-factor or a lot of mess with pitch change effects on handling so much as good, constant, butter churn, at roughly the same speed the engine is turning over at.

Which brings us back to jets. The nice thing here is that stochios are now so hot that total thrust is just incredible and you don’t -need- burner to get 1:1+. Take the burner tube off an F-135 and you still have a 34,000lbst engine and more importantly, you’ve chopped a third off the weight (fixed nozzle) and 1/2 off the installational length. So you put a big fat engine slung in the back with an external USB flap and either direct SDLF or electric fan plenums in a blended wing-body design in front of it. You may not get VTOL but you get 80-100 knot STOL and if you include a spilt reverser on your coanda panel, probably ESTOL. Which translates to a 500ft takeoff and landing capabilities. As good as it gets in a Harrier.

The only question for me is whether you want to chop 5,000lbs off the nose by yanking the cockpit.

Simple monoplane design, twin prop, single engine with a single aero diesel engine. The single diesel engine mounted between the wings will drive a propeller on each wing.

Benefit of D1 is simplicity and efficiency. Drawback, propellers at the back do not help wash air over wings, which limits STOL capability. Disadvantage of D2 is loss of power in the gearing of two props by a single engine.

Twin prop single engine becomes viable at all only because of the high torque of diesel engines.

Sounds a bit like the BAT which had both single centerline and wingtip mounted engine configurations as I recall. Tip mounted (tractor) engines do give airflow over the wing but at the cost of large tipweight effects which effect wing torsional stiffness under load. Obviously this would be less if all’s you had out there were the transmissions from a takeoff shaft but the challenge then becomes one of where you put the systems and fuel displaced from the body by your single engine. I assume you want an internal weapons bay as ‘all the rage’ these days. If so, depending on stance as ground clearance, you will want to have a large side opening door to service a rack system rather than have your ground crew schmucking about under the fuselage and this plus a 2 crew CAS cockpit (big canopy, separate cockpit bus architectures) means you have just sterilized your fuselage. Unless they are just monumentally huge, wet wings don’t carry enough gas and often have squared balance issues for aggressive maneuvering flight which requires compartmentalization and large feeder tanks.

The A-10 and Su-25 frogfoot are great planes but I have three competing designs somewhere in my mind 😀 which I wish this esteemed forum to weigh on. The basic parameters are:

You lost me somewhere between ‘A-10 and great airplanes’…

The A-10 came out of the A/X program efforts which were specifically an attempt by the USAF to undermine the AAFSS AH-56 Cheyenne and thus keep ‘deep CAS’ which is to say BAI/OBAS out of the hands of the Army (they’d already destroyed the effort to weaponize the OV-1 Mohawk).

As such, it was little more than a dumb bomb truck with limited survivability and weather penetration capabilities suitable only for the ‘best days’ (’65-’68) in SEA. Before the SA-7 came south. Once that happened, the A-10 was little more than a fast Skyraider and would have been butchered, even in CAVU (keeping in mind that 3 months in Vietnam you can’t fly anything without blind letdown capabilities because of the monsoons and the VC moved at night with something like 12,000 trucks and 2,500 miles of roadways, requiring every platform we had to be dedicated to stopping them).

When we moved back to Europe after leaving that wonderful region to it’s denizens, the A-10 was -not- upgraded to include such basics as low altitude radalt and terrain attitude avoidance, INS, autopilot, moving map or even TISL (the first 2 years). It had lousy cockpit integration with no UFC and a HUD was little more than an ironsight. All this in weather conditions which, in winter, make the B Maverick all but useless (the seeker contrast ‘assured target lock’ for the vidicon overlaps the gun _rmin_) and makes acquisition of targets from low level all but impossible without a FAC/TACP spot marking. D Maverick was nice but the LAU-88 was not and we didn’t get it until 1986, after ‘The Window Of Vulnerability’ was two years shut.

The jet doesn’t operate well at altitude, having always been short of thrust trust with lousy spool up times and a sharp power dropoff curve that translates to five minute climbouts back to perch leaves it positively gutless over 12,000ft with a further aeroissue as the big fat conical camber wing rides the stall margin anywhere above about 15K.

With the LAU-88 on the jet, drag was terrible and you could not make disengagement turns before crossing into the Zip Gun engagement envelope while the option to popup slow to a gunbunt and then apply power to hold energy coming off wasn’t available because of the rpm lag. Pilots for awhile were running around full throttle with the boards part open and then snapping them closed as the stick came aft. Needless to say, this burned out the cores on the TF34 and greatly fatigued the wings to the point where over half the jets were in need of Hog Up/CUPID type work similar to the early F-16A/C aircraft _before DS_ with less than 10 years on them. They retired most of them to serve as parts donors instead. I understand the TF34 have received flat-rating compression improvements which means they don’t lost thrust going up. But when you have a 40,000lb airframe being pushed by around 18,000lbs of thrust, that’s still all of a .5 T/Wr with half the fuel burned off.

If you want ‘CAS’ done right as a flexible choice, between staging area and roadmarch attack you really are better off sticking with the A-7 as that gives you TISL, a nav-FLIR and dual mode TFR/pencil map within a realistic, six pylon, loadout constraint using standoff PGMs (Walleye and later SLAM) to stay away from the worst defenses around bridges and then transitioning to guns and CBU plus low angle divetoss to avoid the worst of the direct CAS problems (i.e. flyover). There is nothing like an honest 400 knots to get you clean and clear across the FEBA.

In OEF AfG, where CAS availability averaged 11 hours for a fragged mission and anything up to 17 for an unplanned one to be rerouted, Marine CAS was found to be vastly superior to the A-10 because, by the time the Hog cleared off from it’s direct attack, the Marines could put 3-4 providers through the same space using cardinal point offsets, datalinks and a _backseater_ to provide on-site SCAR handoffs with a functional designator.

What the A-10 is good at is escort of rotary wings, CSAR cover force and /potentially/ as a FAC platform. Indeed, the N/AW was a natural for replacing the OA-37 and OV-10 in the night FFAC mission and as a night intruder followon to the B-57 where you desperately needed to have the mission suite and backseater that divided tasks between eyes-out and eyes-in cockpit tasks. The USAF didn’t like the competition with the completely worthless LANTIRN system and so axed what was a cheap and functional pairing of the WX-50 (weather radar) and AAR-42 FLIR with Ferranti LRMTS (lashup) for about 2 million per plane.

On it’s own, in daylight, in Europe, the A-10 was utterly worthless, not least because the FOLs were all within about 50 miles of the front and as DS showed (without the wonderful German road net, in the middle of a desert) that’s about 3hrs before the T-72s are running over your Nikes.

1. Has to be single engined as part of a wider military-industrial plan.
2. Rugged, STOL platform
3. Low cost, cheap, easy to mass produce.
4. Has to run either on diesel or gasoline

Turbines are natural ‘multifuel’ engines simply because they run so hot. AvKer is little more than top grade diesel and while JP-8 has a few additives for accidental ignition suppression and all-altitude performance, any jet will run on virtually any grade of Jet-A1 or better. The turbine in the M-1 can burn gasoline, diesel and avker with the simple flick of a switch (and hourly cleaning of the filters). The problem with turbines is that they don’t scale well and have very narrow operating bands for maximum efficiency (which is admittedly quite high, around 70% burn rates due to the incredible compression as fuel:air mixing but which requires such a huge -amount- of total fuel:air mix, just to keep turning, that it sucks down gas in enormous quantities). What this means is you have to have basic minimum airflow for a given lbst equivalency and your operating range is from roughly 65-70% as flight idle to 90-95% or IRT with equivalent, incremental, differences in fuel burn.

Which is why, if you want to get best median performance on a Mach .7 or below ‘CAS’ airframe, you put a 3,500lbst turbine on it and then use a takeoff shaft to drive a big geared housefan like the P-3 (or the SABA) at about 1,500shp. Problems still abound however because the blades are now chopping so much air at such high RPMs that any flow distortion (as with a pusher engine installation catching boundary crud from a fuselage or wing), combined with significant G force due to maneuvering, can warp and then break the hub boss drive system which, at best, causes the engine to run like a washing machine full of blue jeans and at worst breaks the blades off themselves. Ninety percent of the problems with the Do-335 were do either to lack of cooling flow to the rear mounted engine causing overheats and engine fires or to the damn prop losing it’s pitch synch and overspeeding right off the airplane.

In a CAS environment with a trike I would add that you would be looking at some considerable potential for both ground strike on rough fields and catching FOD thrown up by the nose gear.

True ‘diesel’ engines are most likely rotaries and are selected purely for their high compression state and low vibration for a given engine installation weight class. This makes them ideal for long loiter, high altitude, drone aircraft (cough, Predator Rotax 912/914) where you don’t need or want a highly torqued P-factor or a lot of mess with pitch change effects on handling so much as a good, constant, butter churn, at roughly the same speed the engine is turning over at.

Which brings us back to jets. The nice thing here is that stochios are now so high that total thrust is just incredible and you don’t -need- burner to get 1:1+. Take the burner tube off an F-135 and fit a fixed expansion nozzle and you still have a 34,000lbst engine and more importantly, you’ve chopped a third off the weight and 1/2 off the installational length. So now you’ve got a big fat engine slung between the fuselage booms in the back with some big Fowlers and a USB flap and either direct SDLF or electric fan plenums in a blended wing-body design in front of it. You may not get VTOL but you keep the nose up long after aero stall and so get 80-100 knot landing speeds with rollouts on the order of 500ft. If you include a spilt reverser on your Coanda panel, ESTOL within a 100-200ft run. Add back 300ft for a 35ft obstacle clearance and you’re operational from a 500ft strip length which is as good or better than it gets in a Harrier without all the absurd compromises needed for direct lift as engine-on-CG (yank the wing to remove the power plant etc. etc.).

The only question for me is whether you want to chop another 5,000lbs off the nose by yanking the cockpit as this makes the two-post teeter totter optimally efficient.

Simple monoplane design, twin prop, single engine with a single aero diesel engine. The single diesel engine mounted between the wings will drive a propeller on each wing.

Benefit of D1 is simplicity and efficiency. Drawback, propellers at the back do not help wash air over wings, which limits STOL capability. Disadvantage of D2 is loss of power in the gearing of two props by a single engine.

Twin prop single engine becomes viable at all only because of the high torque of diesel engines.

Sounds a bit like the BAT which had both single centerline and wingtip mounted engine configurations as I recall. Tip mounted (tractor) engines do give airflow over the wing but at the cost of large bobweight effects which create wing torsional stiffness issues under combined roll and G loads. You also sterilize the wing for ordnance (this would apply for a pusher as well, simply because rockets often leave bits of themselves or the launcher as frag and bombs might or might not clear the prop arcs).

Obviously the nacelle endplate and tipweighting effects would be less if all’s you had out there were the transmissions from a takeoff shaft but the challenge then becomes one of where you put the systems and fuel displaced from the body by your single engine. I assume you want an internal weapons bay as being ‘all the rage’ these days.

If so, depending on stance as ground clearance, you will want to have a large side opening door to service a rack stack system rather than have your ground crew schmucking about under the fuselage and this plus a 2 crew CAS cockpit (big canopy, separate station bus architectures) means you have just sterilized your fuselage. Unless they are just monumentally huge, wet wings don’t carry enough gas and often have squared balance issues for aggressive maneuvering flight which requires compartmentalization and large feeder tanks directly over the engines. Ground fire into a fuselage mounted engine with saddle tanks all around it means almost certain fiery death.

Which of these would you choose?

Depending on how critical a rough field capability really is ‘to be near the troops’ (airborne loiter in an unmanned platform for 24-32 hours at a time generally beats FOL pad alert, not least because the fuel/weapons/service equipment logistics and airfield defenses are better done by C-130, 100-200nm further back than 5 CH-47 you need as equivalent forward transfer), I would likely choose a blended wing body design with tip mounted turbofans acting as gas generators for direct gas impingement fans in massive plenums buried inside the wing. Overall design appearance would be somewhere between the A-12 and the XF5U Flying Pancake. The residual, dependent, (think X-32) fuselage being all fuel can, gear bays and weapons mounts.

The fans would be shaped such that they acted more like the paddles on a river steamer with a scimitar geometry that also serve to compress air towards the hub as wing center chord where air would be exhausted through entrainment flap/LID doors using variable vane vectoring. When these were closed for forward flight, equivalent plenum wall ejector slots would open in the trailing edge which, together with the 800-1,500lbst residual thrust from the engines would propel the aircraft forwards. Massive flow mixing would greatly reduce IR signature.

While I don’t pretend that such a system would be as efficient as a rotary wing aircraft for total vertical thrust or a pure linear thrust post for forward flight, it would allow the USMC to move away from skids as beachhead CAS and air mobile escorts and towards a 300knot capability to keep up with the V-22. Where you have 8 skids and 8 harriers in detachment, now you could have 16 total providers with considerably greater operational depth as range.

Given that it’s not a true VTOL, it would have some effects on the operation of helos from a ship, requiring a dual tramway design (runways on either side of the island) but depending on weapons loadout, would probably provide Storch like abilitu to operate with a 50-100ft rolling takeoff as good WOD. While total wing area would be large, spotting factor would be as good or better than most helos for the simple reason that most flying wings are short for span.

Or would you be better of going with a slower version of the harrier setup? Can a Turbofan be made to run on diesel or gasoline? I don’t think gasoline or diesel could be used on a proper turbo fan engine (this is an absolute hard limit in this case).

The Harrier pays way to much penalty in terms of direct lift as safety margins.

If you cannot imagine the notion of balancing on one pogostick, try doing it on four without serious giggle factor and realize that for the ‘privilege’ of riding such a wobbly VL system, you are paying an ENORMOUS penalty in both total thrust losses as you bleed the fan to the front engines and turn the core efflux, aft and IR signature. The latter creating hotspots all along the fuselage which have to be broken across massive steel deflector plates, adding to the jets efficiency issues in up and away performance.

You can’t really use plenum chamber burning in forward flight, even on the aft nozzles, because you don’t get good thrust recovery from the fixed expansion nozzles, while in the hover, you already suffer massive hot gas reingestion issues to the extent that you have to cool the airflow with water injection to get enough thrust for a VL. You -might- do better with a tri-post system and either a throat cutoff to a lower hemisphere fenestron or a lobster tail aft nozzle.

The latter providing you with at least the potential of a true AB as opposed to micro PCB. Even so the wing would have to remain tiny because of the added weight of burner can etc. which means your internal fraction is going to be so low as to make burner use of questionable utility.

As is, the Harrier fuselage is largely sterilized (due to CG displacement as much as volume stuff) and the gear arrangement is awkward and not really suited for a conventional landing in the event of failure in the admittedly reliable ‘bicycle chain’ nozzle control system (about the only thing on the jet which doesn’t brake with alarming frequency).

The big problem with the Harrier is that everyone thinks all landings should be ‘better to stop then land than land and hope to stop’ controlled VLs. In fact, crash statistics all show that 90%+ of Harrier accidents happen somewhere in the 100-0 knot transitional regime and for this ‘privilege’ of crash and burn predilection, you trade away all the airframe configuration options which might provide a better lift cushion as more stable rolling-VL or ESTOL within a _better_ total runway footprint.

Because Harriers ideally need about 1,200ft of runway and never operate out of less than about 400ft with any kind of reasonable weapons load (all of two tanks a LITENING pod and either APKWS or a GBU-12 in AfG, whoohoo!).

Comparitively, super STOL as a function of a blown airfoil and/or a MUCH larger fan plenum provides a genuine ability to keep the entire airfoil under lift while landing with predictable touchdown point control in less than 100ft and with takeoffs in a similar 200-400ft regime as a function of -normal-, not decklength or telephone pole constrained, shortfield operations from roadways.

Weapons loads would still be an issue but with the transition to ATGW for most CAS missions you are looking at stubby, light, multi-rack capable systems which can actually be tandemized across the full chord of a wing or fuselage weapons bay with a 2,500-4,000lb loadout limit still providing a good number of passes. About the biggest problem here being the need to adapt the weapons from forward to drop fire and/or accept the weight of extendible weapon rails (I prefer dropfire with tubed encapsulates as it allows you to stack weapons).

In terms of ‘contested’ that’s going to depend a lot on coming changes in the threat technology base. Right now, the step from shoulder fire systems to mounted weapons on ADV is pretty extreme but in theory, _if you can pay for it_, anyone should be able to purchase netfires type systems which effectively put much larger (MRM = 240-400lb MICA or Adder) weapons as dumb launch boxes into the field via Humvee or even Mutt class (as prime mover to a trailer) system that would challenge even fixed wing aircraft. Binocular optical rangefinders, on a GPS enabled stand would let you preprogram associated launchers as seeker IMUs to look for specfic targets with ease.
Now move towards a truly advanced turbine-powered system, ala MALI, and you can shift to 100-200nm _ranged_ fires from considerably fewer launch boxes with a 200-300lb weapon that has the long-burn impulse equivalet to actually _hunt for targets_.
No cuing required, just call in your location and Habib, using a digital coordinate map for “Somewhere near Najaf…” point and clicks with his IPad and the weapon treats an entire cube of airspace as a hunting zone.
Beyond which, the next generation is obviously DEWS as either HPM or Laser. neither of which will miss. At the moment, these are severely range and cost constrained, the typical Rheinmetall unit is good for about 1.25 miles which prevents overhead CAS but doesn’t protect from standoff weapon attack (though it can shoot down missiles inflight). I have a feeling that there will be considerable maintenance of the optics required to keep these weapons functional and they are NOT going to be pickup deployable anytime soon, simply because they need a considerable amount of electrical generation.
When hunting and DEWS systems become standardized, you will see an almost total abandonment of manned airpower. Missile and drone systems will continue to be employed, simply because there is too much to be gained from even partially successful disruption of rear area logistics and transportation interdiction. But manned airpower will fade.
As the others have implied, CAS effectors are not well suited for operations in high air threat environment for the simple reason that, towards the cheap end, they typically lack the dedicated volume search and A2A weapons system capabilities to be effective weapons platforms. Indeed, one of the continuing justifications for using the F-16 in place of the A-10 was it’s _radar_ ability to sanitize the airspace over and beyond the target area for battlefield sweep assets. Yet the fact remains that this is a _very_ lethal environment for the air superiority platform as well, not least because any high intensity fight where they are likely to be encountered will also be populated by S2A systems which functionally drop their altitude as F-Pole standoff advantage to a level where they lose much of their BVR superiority.
Down low, going fast can effectively impale you on threats you weren’t aware were present and so when-not-if the high speed assets are driven off or otherwise ‘too busy’ (retained for strategic strikes as tying dow equivalent enemy airpower DCA to the defense of major economic assets.) in the face of heavy attrition as battlefield effectors, what tends to happen is that CAS meets CAS in a manner that is very adhoc and improvised at first and becomes more studied as deliberate ambush later.
This happened in the Iran:Iraq war where Hind met Cobra and Cobra and the Cobra used both cannon and TOW to beat back the Hind’s superior speed and ACM rotor system as a strafe platform. The Iraqis in turn mounting Soviet supplied primitive SAM conversions on the Hind AT-2 endplates with mixed results (IR MANPADS _do not_ like to look down into clutter) and then both sides began using PC-5/7 as turbotrainers with gunpods to deliberately seek out helicopters before the provision of advanced VSHORADS (RBS-70 to the Iranians) and the extension of radar SAMs coverage as (HAWK vs. SA-2/3 using gapfiller radar cuing) drove everyone back a pace.
It is in fluid-battlefield conditions like this, before fronts stabilize and IADS overlaps become unbreakable without a major SEAD effort, that you will find most unintentional A2A engagements happen as dedicated assets are busy in other missions and platforms without role dedication as specific asset abilities (LCOSS for one) become victims of coproximity on an almost WWI level of rifles-out-the-window engagement.
The best that can be said here is that leopards don’t hunt wild boar, they hunt piglets and if you are in a low energy airframe without the knots as near horizon to extend from a SACLOS or especially SALH ATGW environment, air combat tends to devolve into an ‘elevator race’ to see who can get above the enemy rotor disk to mask their weapons and free your own. This typically ends in a ‘died second’ condition where topout clears the clutter enough to catch a MANPADS.
The worst condition you can expect being that of a hide bound position where the threat tops you in a fast slash as you stalk tanks or whatever. RAH-66 was conceived, at least in part, to provide standoff protection against Hind sweeps over an active engagement as the Mi-24s themselves fly in three ship reverse vics looking for trouble with the flight lead at the rear spraying down whole areas with the UV-57 or 80 rockets. Destroy the shooter and the eyeballs don’t matter. Blind the eyeballs and the shooter can’t find anything to shoot at in time to make a difference.
It is this ability to standoff with sensors like the APY-8 Lynx (15km) and the AAS-52 MTS (35km) allowing considered tactical decisions with wide FOR situational awareness that makes UAVs as dominant as they are and such a trend will continue as surface defenses become more powerful. The counter being cyber within the high bandwidth video links.

LEG

ThinkPlum,

putting when & where questions aside, I’ve been curious why they gave such extreme flexibilities to the canards and tail fins. it has not been seen flying with canards or tails moving to that threatening angle during turns, take-offs, or landing yet, and I seriously doubt such vertical position of canard will be allowed in any manned fly-by-wire control software. And if J-20’s role is a long range stand-off platform as everyone suspects world wide, the hell is that configuration for? or Won’t it cause serve stresses to the air frame during dog fights, let alone human physiology？

Generally, the massier a jet is, the more control displacement it will take to overcome inertia for any given moment arm away from the center of lift. The J-20 is long because the AL-31F is long and the weapons bays are long and to get both in tandem while accounting for supersonic migration of center of lift in a no-TVC airframe, they had to split the effective airfoil lift ahead of and behind the center of gravity.

Putting canards on an RSS jet allows you to push the nose down rather than the tail up as the two easiest roads to controlled agility at subsonic speeds where simply relaxing trim allows the unstable aircraft to naturally pitch, augmented by the stabs or canards as needed for rate and stabilization at desired AOA.

No traditional empennage means no tail boom which also has implications for the structural load requirements on a rigid body fuselage with LO concerns driving an internal weapons bay (long fuselage midbody instead).

That said, the real problem comes as you transition through transonic and into supersonic realms where traditional Bernoulli Principle lift fades and thin airfoil theory is augmented by the Mach shock redistribution of lift well past the quarter chord point of the airfoil. Where exactly this occurs (longitudinally along the fuselage) also dictates a lot of your wave drag as ruling distributions but most importantly, it causes ‘Mach tuck’ as the nose wants to submarine.

Draw a triangle from the nose to the wing tips. The more acute the angle, the ‘later’ (faster) before the Shock starts to redistribute lift and move the ACL back.

Delta wings are good for their large sweep angles and long chord as total area compromise in supplying a relatively even lift distribution at a variety of speeds, but they lose control authority as a function of downforce required to trim the aircraft as it goes through the transonics.

The canards, while largely worthless as fixed control effectors at this point, can still act as powerful forward LEX to keep the nose from plowing under and thus allow the aftset wings to keep the heavy end (engines) under lift while the canards narrower span also doesn’t interact with the shock off the nose as badly (as a trapezoidal, midbody, fullspan wing like the Raptor’s), helping with area rule.

The JAS-39 canard deflection is of course necessary to act as a replacement for the Viggen’s thrust reversal STOL ability while the canards on the J-20 may not have that much deflection authority, relative to the size of the surfaces and the expected braking effect for that size aircraft. Immediate deployment of canards as spoilers makes aerobraking impossible and is generally unnecessary on a jet with drag chutes (though it is more effective/safe in crosswinds or on icey runways).

The likeliest reasons for the J-20s all moving verticals is both to provide added keel equivalent as directional control in what are relatively small surfaces (as drag reduction measures and also to keep them out of the vortice paths coming off the canards) and also, quite possibly, to augment trailing edge pitch authority in supersonic turns. There is enough cant in both tails to provide a significant pitch modality in their combined deflection.

Blitz,

The problem with the door system as shown is that it is vulnerable to sub-feature alignments as materials changes. All objects have both optical (think mirror) and resonant dipole (say tuning fork) Mie/Rayleigh target qualities in the radar bands and any change in the surface contiguity as a function of cutout perimeters, underlying structural voids and material densities artifacts will change the way the radar ebbs and flows around them.

If you’ve ever stuck your hand under a running faucet and turned your wrist only to watch the water climb halfway up the other side as Coanda Effect, rest assured that radar does much the same as surface and travelling waves charge up the skin and where ever they come across the aforementioned surface feature changes, undergo impedance loading until eventually they backscatter ‘against the flow’ (180` opposite of wave travel) towards the emitter.

Most such subfeatures are fairly small and aspect-dependent such that they form ‘fuzz’ instead of ‘spikes’ like porcupine quills. But modern radar receivers are so sensitive that unless you kill everything, they will make do with the fuzz even if the primary spike returns are all gone. By this understanding, you have to realize that small features can have fuzzy return effects well -beyond- WVR engagement distances.

There are also structural concerns in play, given that you are adding corner stresses to the composite where a lot of stress loading is going to accumulate fatigue and this could theoretically induce early cracking as well as tolerance changes, particularly in certain portions of the envelope. Ideally, you would have the surfaces chamfered so that you distribute those loads over the maximum area in compression but if there are in fact two separate ‘door stop’ devices (for extended and retracted position on the rail swing-arms), you would have to give precedence to the closed position to form a tight seal RF as well as aeroseal and this means that you could further compromise, not just the immediate area around the arm protrusion but the entire bay panel with flexure in the surrounding skin.

Indeed, in one of the original J-20 images of the aircraft coming in to land with the missile rail extended, you can see that the main sidebay door has failed to close fully. NOT a small problem for either RCS or aero structures purposes.

Finally, the one thing a missile rail does is provide longitudinal rigidity to the weapon trajectory upon release as the motor impulse applies a not inconsequential shake-and-shimmy aero acoustic load on all transverse axes. This is relatively easy to accomodate when said rail is attached to a wingtip or a pylon, but very hard when it is swinging free in space on a long moment trapeze arm. You can CATIA optimize the load paths but such design considerations tend to limit you to the specific type of missile which the rail has been specifically engineered to accept the twist and shudder loading from.

If, for instance, you wanted to clear a variant weapon with more thrust or in fact a different class of ‘self defense’ capability altogether (PL-12 is a better match to PL-15/21 than PL-10 ever will be, kinematically), then you would likely need to reposition the swing-arms to accommodate a different rail as a function of direct and harmonic load absorption from a longer weapon with more keel effect.

And while this might be possible (based on side bay lengths having growth margin) _if there is no cutout in the skin_, once they are there, suddenly the whole ‘clever idea’ becomes a design trap as the bay to arm to rail geometry becomes fixed.

LEG

I admit it’s not a perfect match but then the CM-400 has at least two known configurations, neither of which has been ‘confirmed or denied’ as the basis of actual Chinese production design. The first, as a brochure, looks a great deal like the Standard SM-1. The second, from an airshow sitting next to a JF-17, looks a little bit like a PAC-3 ERINT.

Neither of which are appropriate for an AShM which has any intention of beating the radar horizoning effect by coming in low or of executing a terminal evasive profile while seaskimming.

The former geometry has too much drag from the long body strakes while the latter has too little lift at the mid body point and so would end up skidding badly, losing massive amounts of energy as induced drag as it tried to surf it’s own Mach shock coming off the nose. You really need airbreathing systems to make such energy trades and that’s what the YJ-12 is likely for in conditions where the airborne horizon extenders are dead or driven back and you can afford to go to external carriage using sub-horizoned approaches (with your own airborned or satellite targeting).

OTOH, both CM-400 configurations shown could be useful designs for an aeroballistic weapons system, lofted for range and then coming back downhill like a V-2 at Mach 5 or so where there is so much energy that tiny control deflections create massive shunt displacements of the velocity vector as target track line. Costly? Certainly. But if you are engaging the USN or USAF protected assets with upwards of 400 SAMs coming back the other way, you don’t use glide weapons whose every mix-and-match KMU protuberance and seam discontiguity sets up a resonant dipole scatter, even in the X-band.

That’s just too huge a target radiator and too many cleanup repetitions of engagement to get shots on moving targets with secondary CIWS/RAM/LAWS terminal defenses.

OTOH, knowing what they are designing for as the mission point (kill the Carrier beyond/before DF-21 reach, engage ‘low value’ close-in SAGs or attack open-ramp Andersen BMC3 ISR assets) tells you their intent as justification for a fully sleeved warhead and a very high (literally) terminal profile energy to beat ERINT and ESSM/Standard.

The key to reaching a change in perspective here is that CM-400 is described as having a 5.2m length and 1,000kg weight-

http://defenseupdates.blogspot.com/2012/11/cm-400akg-missile-at-zhuhai-airshow-2012.html

Which would indeed be too long and probably too heavy for the J-20’s weapons bays (and likely for the JF-17 underwing pylons as well).

But this-

http://4.bp.blogspot.com/-eYV4yn5u6AI/UKVBIaEuMXI/AAAAAAAACc0/ZqzWQzRnBZs/s320/CM-400AKG+ASM+Poster.jpg

http://i.imgur.com/VSqGI.jpg

Is not a 17ft weapon.

Indeed, if you look at a Standard missile diagram-

http://www.vatsaas.org/rtv/arsenal/teamrocs/sm2hp/standard-arm1.gif

It becomes very clear that any weapon which -did- emulate Standard would only be approximately 4.5m/15ft.

I don’t think CM-400 is that long either.

Indeed, conceptually, what the missiles in the J-20 bay remind me most of is the Russian Kh-38-

http://m.ruvr.ru/2013/01/18/1335610606/800px-Kh-38_in_maks2009.jpg.1000x297x1.jpg

But with an emphasis upon a much higher hypersonic (from the airfoil shaping) aeroballistic cruise profile likely derived from a higher (J-20) supersonic launch condition.

The Chinese are investing in a layered silver bullet force capability to handle threats which their MRBMs cannot reach or target or which the PLAAF feel aren’t worth the expense of ballistics. They are using the very long bay of the J-20 as a means to leverage inferior RCS norms with very much superior standoff compared to what we are used to seeing.

And they are not trusting to saturation of a few subsonic glidebombs (though this is likely why the weapons bays are so deep, to provide added clearance for SWAK hardbacks on the FT/LT/LS series) to beat back the U.S. S2A response. For that would be a silly waste of a limited 4-ejector bays count for weapons which are approaching from <60nm out at a measly .7 Mach or so. Never mind the bombs the J-20 force itself would be subject to being wiped out by both ER Standard and PAC-104D, as well as any FORCAP/BARCAP or even QRA force.

Where the Chinese have a major edge over us is in their no-patent recognition ability to generate families of weapons using interchangeable components and scaling. That is the evolutionary progression you see in their developmental history of the 7710 LGB (as Paveway 1) capability moving through the LT-2 as a BGL/KAB equivalent to the LT-3 (as GBU-54). And now the FT/LT/LS series are largely interchangeable with different warheads as guidance and range extension kits. Bypassing P3 altogether.

As such, it becomes really simple to see them mixing and matching missile bodies, motor length as impulse plateaus and even front end seeker configurations. Simple rockets that do all of their boosting from a single performance point optimized profile have huge complexty and weight trade advantages over ramjet weapons here and may be able to trade kinetics for absolute warhead sizing as well. Take out the SPY-1D or SPY-2 ‘through the CIC as the exposed antenna face’ and the AEGIS is just another bulk carrier as mini arsenal ship.

What remains to be seen is how they intend to target their weapons at range. Whether they will simply use preplanned image templates (in which case the J-20 is really just a bus and will not need, for instance, a second seat WSO) or if they will attempt to employ live target sorting as a function of onboard recognition or even MITL target designation from a separate VLO drone or ballute/paravaning missile targeting package.

The less datalinking they do, the less vulnerable they will be to cyber but the more decoys will work and the more restricted target sort to morte` allocations for weapons which are coming down hill from 80-100,000ft at over a mile per second.

Yup… A) Your enemy would probably be able to SEE you through his canopy and target you using his HMS…B) His main weapon for targeting at that range would be a High off boresight IR Missile which does not care about anything other then IR signature… Where such a design could be valuable is to see launch times and how REDUCED they are compared to the fast ejection rail types…which from what we see are quite quick…..If this can significantly reduce that time it may give a SLIGHT advantage, but for me its main thing is its COOLNESS FACTOR 🙂 ..

I would argue that the HOBS environment is entirely predicated upon slow entry speeds which, in a massive jet like that is asking for trouble, simply because you’re reacceleration curves are going to be abysmal.

Beyond which, people think of time as how long from when you press the button to when the missile leaves the rail. I would instead argue that it’s how long from the moment of your last BVR shot until the first opportunity at the radar or visual merge for the 10km motor’d weapon to pole match the threat which has been shooting at you for the last fifteen+ miles at least.

HOBS being all but useless outside of a 40 or at most 60 degree offboresight condition because you’re shooting a 200-250lb weapon, only 2/3rds of whose total mass is motor, with consequential effects upon the kinematic envelope, even before you further deflect the airframe as the trajectory curve with applied G.

An AIM-120 _already has_ LOAL with datalink and a 60mil ASE circle which means, assuming it’s a standard metric for all MRMs, it’s percentage motor to total mass also means that the bigger round has a better chance of making it across the elbow or even over the shoulder (after a little waddling to be sure) than any SRM.

Cueing then being a bigger problem as you don’t want to pitbull the round but you may not have the convenience of someone stood off and able to provide illuminator cueing to your FCS so that it can tell the missile where to go using a non-radar imbedded comms channel.

Since I’m probably one of the few who still believes the J-20 is a special mission platform like a supersonic F-117 (or stealthy B-58) with a deliberate emphasis upon attacking select ground targets as the raison detre` of it’s overall mission role to snipe support mission aircraft (because you know where these USAF predominant aircraft have to land and the weapons bay is clearly too deep to be intended for conventional systems) the reality then becomes needing more long spear weapons to chuck at any enemy you happen to tangentially encounter _at a distance_.

Because, you see, to me those aren’t Pili-12 or 15 derivatives we saw in those weapons bays. If nothing else, the noses are too pointy to fit a mechanical array with nod-room, even as the missile bodies look more like 10″ (HARM class) than 7-8″ AMRAAM or Sparrow derived. What you are looking at in those weapon bays are CM-400 AKG or derivative weapons. Which themselves are Standard LASMs clones.

Now, admittedly, Standard also makes for a very nice SAM and so presumably could function like an LRAAM. But the point is that if you have a principle strike and/or A2A weapon which is capable of -at least- 150km standoff, you have no business closing with a threat for 80nm to unsheathe your bootknife. Your next graceful step down is going to be somewhere around 40nm.

What you do if jumped close-in is you defeat the HOBS attack (which should be fairly easy, based on the amount of motor energy it has to use to weathercock across the circle) and then you either extend and escape -or- you unload and pitch back with a much better 6-8nm weapon. The AMRAAM is actually quite a good dogfight system, if only because it trades boresight data a lot more effectively than the AIM-9 does.

If the enemy is coming crashing down on you at typical 20-40nm BVR ranges while you are midcourse umbilicaled to either an A2A or A2G weapon which has another 70-90+ seconds of flight time, the AMRAAM class weapon is a better choice for fending them off. If only because it means all four of your primary stations are available to attack the ground threat or loitering BMC3/ISR platform.

Anything short of a long burn Alamo-T would be a waste of time here.

Given that the original ATF spec for the YF-22 (longer inlets = more space) included the ability to fire -either- AIM-9 or 120 from the sidebays before the intakes were cut back to improve downwards vision as lip shock recovery, the only excuse the massively longer J-20 can have for continuing with SRM in this position is that the higher energy motor acoustics from anything bigger form too great a risk to the fuselage or weapons bay in rail-forward launch mode.

LEG