Amiga500Spine
Wings
LEVCON’s
Engine
Engine exhaust
Horizontal stabs
Stinger
Area in between exhaust and stinger
Vertical stabsSooo… every single area that is seen. I am not overstating it, i literally see mistakes in every single of the things i listed above.
That is a particularly useless answer.
How about maybe saying what is wrong with each particular bit?
[Not that I expect an accurate model to result, but give FD a chance to improve what they have.]
Amiga500What is the red circle indicating? Too wide? Too fat? too far, too short?
The engines/engine intake ducting appears to be mounted too high in the model.
The model has a significant blend to the external “fuselage”, whereas on the actual aircraft, this part of the fuselage follows the contours defined by the fuselage, and not by a blend to the engine/engine-intake outer mould line.
Edit: There is a clear change of upper surface contouring between wing and outer fuselage. This is not reflected in the model which retains an identical suction surface curvature for wing and upper fuselage. Thus, it could be that the outer fuselage suction surface is not high enough, rather than the engines simply too high – or a mix of both.
Good luck determining which!
Amiga500Anw UK did not obtain source codes, did they?
I believe so, eventually, after some negotiating.
[On another note for any UK members; John Fortune, who did one of the funniest sketches I remember on the F-35/RN carriers on Bremner, Bird & Fortune, unfortunately passed away there earlier this week.]
Amiga500If there really was a market for 5th generation combat aircraft flying on completely ‘open-source’ software,
Open source?
As in open to the customer who pays billions for the package?
Or open as in, open to the whole wide interwebz?
Not seeing your logic with that argument.
Amiga500That is a danger that can be found in the technology sold by any country – who could trust the software in a J-10 or SAAB Gripen?
If you can actually see the code and customise the hardware as you desire, you can at least have your own people attempt to ensure it works as advertised.
Amiga500Here is a question.
– You are a potential foreign customer of the F-35 that is not the UK.
– You read all this stuff about the NSA putting software and hardware into devices to spy on both Americans and foreigners – all in the greater interests of the USA of course.
– The US will not give you access to the source code for the aircraft.
Do you really think that the aircraft will not be adversely affected by malicious code if you were to attempt to use it for missions contrary to US govt interest?
Amiga500So why are there hardly any intercontinental jetliners with aft-mounted engines?
Engines are too big and heavy. The structure would mean the fuselage is heavier than sensible, the wing moves nearer the rear of the aircraft so the tailplanes needs to be bigger. Which moves the c.g. further back, which means the wing must be even nearer the rear of the aircraft, which means the tailplanes need to be even bigger which means the structure needs to be heavier…
Oh, and the engines mean you need a T-tail, which is heavier than a conventional tail, which moves the wing nearer the rear which etc etc…
Is it for ease of maintenance – easier access to the turbofans on larger aircraft?
Partially.
Are there aerodynamic disadvantages to aft mounted jets on bigger airframes?
No, the clean wing is aerodynamically advantageous. Albeit not by much in the case of good wing/pylon integration.
edit: Oh, and jet-pump fuel feed to aft mounted large engines is a bollox, so you automatically incur a lot of hazardous and catastrophic safety issues with your fuel system. The size of the CRJ engines coupled with the real length between wing and tail means can get away with a jet pump system, which will deliver fuel when the engines are running – entirely passively. That would not be the case for the widebodies.
edit2: An advantage of rear-mounted engines is a shorter undercarriage – which allows easier use of a built in stairway. Single-aisles now have automated stairways built in too – this was a big deal for the likes of Ryanair. But for loading/unloading widebodies, such approaches aren’t really feasible, so the undercarriage height isn’t so big a deal, and funnily enough can come with service access advantages.
Amiga500You have to play the cards which are dealt to you.
In the mid-1990s, President Clinton’s administration would only agree to fund one new start fast strike jet program. It had to be common to all three services (Air Force, Navy and Marines). The alternative was to continue to use jets designed in the 1970s for the strike role until the 2030s. And it was dubious that the teen series jets could be rebuilt to provide a 50+ year service life.
See, there is your problem right there.
What the f**k do the Congress, Senate and President know about designing aircraft?
No engineer can turn such bad fundamental program level requirements into a success. Its like trying to build a house on quicksand because the local mayor says so.
Amiga500REALLY? Go check the dimensions and thrust-class of all three versions of the F35 and your so call equivalent fighters that some are championing as better of the same class…they all must be pretty bad too.
Sorry, your right; I shouldn’t be focussing only on the conventional definition of finesse ratio; I should be highlighting the fuselage volume:fuselage length.
Amiga500But anyway, this shouldn’t focus on F-35 alone, even if it is the ultimate in “joint” thinking gone awry*.
Here is a question; the Panavia Tornado was designed and built before my time – could any of our more learned posters/the old codgers kicking around shed some light on its gestation?
Is it an example of not only a “Joint” program, but a cross-border “Joint” program which didn’t over-run on budgets to a large degree? [can the technical issues be separated from political?]
*the degree of which is dependent on your view on the program.
Amiga500How so? Was mentioned before, but not very memorable. Must not be that important.
Not very important? Am I confusing you with someone else?
1. Limited length of airframe, which limits finesse ratio – severe drag implications.
1.(a) Which limits nose size and thus radar size.
2. Limited wingspan of airframe, which limits wing area – severe lift implications.
3. Defines single main engine.
4. Defines internal volume (that finesse ratio again), which limits small carriage and ensures severe system installation issues.
5. Defines maximum airframe weight, which requires severe structural compromises and fatigue/durability issues down the line.
The LHD requirement has f**ked the program. Lockheed can only do so much when handed such a bad requirement.
Its like asking someone to design a high performance car but use 165 mm wide wheels and a 1.0 litre engine.
Amiga500If the USN had sway to define a bigger plane with two engines while the USAF and USMC got their wish for a lighter plane, but all three shared the core electronics, communications, sensors, and so on then is it really such a performance unfriendly program?
Thats exactly it.
The USN and USAF should have had two separate designs based on common technology where possible.
Same radar. Same MAWS. Same RWR. Same weapons. Same IRST. Same engine (2x F119 development in USN, 1x F119 development in USAF).
It all went horribly wrong when it was mandated that the USMC LHD requirements had to be met with this common airframe. That was the fundamental error. Even now, I’m not sure that error is widely recognised; certainly amongst many on this forum or in the Pentagon it would not appear to have received much attention.
Amiga500Its even stranger when you look at the backlog.
If there were fundamental issues, or problems that remain unresolved, you’d think no-one would be ordering new builds…
Amiga500Why would a dedicated fleet defence fighter be inferior in that role to a bloated jack-of-all-trades aircraft? Surely it’s the other way around — the reduced performance offered by a ‘joint’ aircraft in any given role offsets savings in development/logistics/etc.
Whoops that wasn’t very clear – kinda meant the opposite.
Amiga500Interesting. No mention of long term logistics. They only focus on the acquisition aspect.
Having six different aircraft is definitely far more expensive when we factor in maintenance and logistics.
The economies of scale are not linear though.
But regardless, there will be a crossover point somewhere between:
– R&D costs
– Build costs
– Operating costs (everyday costs, fuel, pilots, oils, short term wearing items)
– Maintenance costs (long term wearing items, unexpected repairs)
– Mission failure costs
And of course, not forgetting:
– Mission success savings
[the last bit being quite important and something pretty much all bean counters miss – after all, what use is a “Joint” fleet defence fighter that costs $5 million less to buy and $0.5 million/year less to operate if it means your $8billion+ carrier is sunk?… which then leads on to your $1 billion destroyers getting sunk and your ground units getting killed.]
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