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lukos

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Viewing 15 posts - 1,291 through 1,305 (of 1,752 total)
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  • in reply to: Malaysian Airlineus 777 shot down over Ukraine #2286954
    lukos
    Participant

    MH370?

    Okay, I’ll get my tin foil hat.

    in reply to: F-35 News, Multimedia & Discussion thread (3) #2286976
    lukos
    Participant

    The pressure ratio of the M88-2 is 24.5 and the bypass ratio: 0.30
    For the EJ200 PR: 26 and BPR: 0.40
    For the F135 PR: 28 and BPR: 0.57

    So a higher PR should logically mean that the turbines extract more work from the hot gas during expansion, hence resulting in more cooling prior to jet-pipe.

    in reply to: F-35 News, Multimedia & Discussion thread (3) #2287148
    lukos
    Participant

    I actually have a question on the engine. A BPR of 0.57 has been stated, however, AIR International say that 57% of the air goes into the bypass stream. Now that isn’t the same thing to my mind and would actually give a BPR of 0.57/0.43 = 1.33.

    in reply to: F-35 News, Multimedia & Discussion thread (3) #2287157
    lukos
    Participant

    And what’s the pressure ratio? What’s the bypass ratio? Simply comparing turbine inlet temperatures is ridiculously simplistic. Not to mention that most of the engines you’ve listed are typically mounted in pairs.

    Exactly. A high Turbine Entry Temperature generally just means a more advanced engine with better thrust-to-weight. The F-35 engines have a higher BPR than most other fighter engines, so the cooling bypass stream should shroud that temperature more effectively and the nozzle temperature probably isn’t higher to begin with and especially not after the BPR cooling effect.

    in reply to: Japan's stealth plane #2287373
    lukos
    Participant

    I was kind of excited by the idea of a small stealth aircraft with smaller A2A weapons. Kind of like POGO, except with a brain, if you will.

    in reply to: Japan's stealth plane #2287430
    lukos
    Participant

    It’s a sub-scale technology demonstrator, & unlikely to be armed. Weapons bays would have to be sub-scale for sub-scale weapons . . . . or maybe just missed out, because of what it is.

    Ah, now it makes more sense.

    in reply to: Japan's stealth plane #2287448
    lukos
    Participant

    Most likely to “hide” the zig-zag doors as well as several smaller panels.

    Zig-zag doors are nothing new.

    Anyone noticed the high impact main landing gear ?

    Don’t they normally use 2 wheels for carrier aircraft though. But then that would make sense for the blurring. Japan isn’t officially supposed to have aircraft carriers or be thinking of them.

    In the model, it seems to have a split intake on both sides???

    The size is a concern. Looking at the size of the ground crew next to it, it’s difficult to see it carrying more than 2 AMRAAMs internally.

    For a stealth concept it’s strange to not notice some doors for weapon bays, do you think it’s possible they put it on top, in the rectangles between the wings and fuselage, or maybe it’s just airbrakes..?

    Those two, if you’re looking at the same ones as me (last photo in multi-photo pic), seem too small. They’re only about the same length as the ground crew person at best, and he’s probably about 1m short of AIM-9 length.

    I hope they don’t cancel CUDA.;) In fact that’s my best guess on armament. There doesn’t appear to be any provisions underneath, so perhaps it’s just going to be 4 CUDAs in those twin doors either side on top of the wings.

    As regards the blurred bit in front of that, I’m going to make the bizarre guess of smaller short-range homing rockets for dog fighting, again using HTK technology.

    in reply to: F-35 News, Multimedia & Discussion thread (3) #2287467
    lukos
    Participant

    http://www.slideshare.net/Picard578/stevenson-f-22-brief

    Just scan-reading this article, there’s already multiple errors.

    Page 30 – AIM-7N ARM used in Desert Storm
    Nope. AIM-7Ms was used in Desert Storm and these are SARH missiles not ARMs, they’re designed to home on friendly radar reflection not enemy radars.

    Page 33 – All radars off in next war
    Sure. SAM sites turn their radars off and get picked out by satellites and bombed.

    Page 33 – This is what happened in all previous wars.
    Really? I could have sworn it wasn’t you know.

    Page 46 – Rearward visibility sacrificed for technology.
    AAQ-37 EODAS has full sphere optical and IR detection on a range the human eyeball could never hope to achieve. It is all relayed to the pilot via his helmet.

    Page 54 – AMRAAM Pk justification based on Desert Storm.
    No it wasn’t, it was based on actual combat performance during the Iraqi NZ enforcement and Operation Allied Force.

    Page 61 – Weight comparison…
    Completely wrong. The F-22 weighs about 64,000lb with 6 AIM-120s, 2 AIM-9s and 480 20mm rounds and about 61,000lbs with just fuel.

    http://www.lockheedmartin.com/us/products/f22/f-22-specifications.html

    Page 62 – TWR comparison…
    Obviously this is wrong too due to aforementioned and horribly incorrect thrust assumptions for F-15A engines.

    Page 63 – Acceleration
    Not even going to ask what horse**** that’s based on.

    Page 64/65 – Wing Loading
    Obviously incorrect due to incorrect weight assumptions.

    Page 67 – Fuel Fraction
    Lot of errors here too. E.g. F-16C should be 7,600/26,500 = 0.286. F-22 actually comes out higher, hence it was missed off LOL.

    Page 70 – F-22 Fuel Fraction
    Yep, wrong. 18,000/61,340 = 0.293

    Page 71 – Flight Envelope
    The F-15C Flight Manual proves it wrong. As for the F-22, I sincerely doubt anyone knows.

    Page 72 – Miles per lb of fuel
    Load of rubbish.

    Page 74 – .50 cal has quicker time of flight than 20mm Vulcan
    Yerrrr…. no!

    http://www.quarry.nildram.co.uk/ammotable2.htm
    https://en.wikipedia.org/wiki/.50_BMG
    http://www.quarry.nildram.co.uk/ammotable2.htm

    Page 74 – Cumulative Lethality – .50 cal vs 20mm
    An M61A2 fires almost the same amount of rounds in the first second as half a dozen M2 Browning operating at 1,000spm each. Each round contains 10.7g of PBXN-98 (or similar). Largely irrelevant of course but the information is unsound at a fundamental level.

    Page 75 – Missiles require 10-15s to lock
    IIR missiles are virtually instantaneous.

    Page 76 – Assumptions
    Ignores actually combat Pk of AMRAAMs and instead assumes a terrible value, then assumes a fantastic Pk value for a passive radar homing missile, which has yet been completely untested in combat, in fact no passive homing BVR missile has ever been tested in combat against a fighter jet target, and HOJ is usually regarded as a less reliable secondary homing method.

    lukos
    Participant

    I seem to remember some other improvements being explored a few years back as part of a Team Complex Weapons press release, I believe one of them may of mentioned an increase in range but I could be wrong.

    Maybe there’ll be some kind of ESM capability for anti-shipping.

    Possibly related news:

    http://www.baesystems.com/article/BAES_175145/taranis-demonstrates-stealth-capabilities-in-second-phase-of-flight-trials?from=twitter-plc&_afrLoop=361635477912000&_afrWindowMode=0&_afrWindowId=null#%40%3F_afrWindowId%3Dnull%26_afrLoop%3D361635477912000%26from%3Dtwitter-plc%26_afrWindowMode%3D0%26_adf.ctrl-state%3D1a60i1oeqd_1543

    http://www.baesystems.com/cs/groups/public/documents/digitalmedia/mdaw/mtkx/~edisp/~extract/BAES_175152~1~staticrendition/492x277.jpg

    Taranis – the most advanced aircraft ever built by British engineers – flew in a fully ‘stealthy’ configuration, making it virtually invisible to radar during this latest set of trials.

    In order to achieve an unprecedented level of stealth, the team changed all antennas on the aircraft to signature control variants and the air data boom on the nose of Taranis was removed. Following these modifications Taranis used a specially-designed system which allowed the aircraft to generate a full set of flight data, without the use of an external probe or boom.

    Taranis also used a cutting edge communications system to ensure it was able to stay in touch with its mission commander without giving away its position to the enemy.

    Minister for Defence Equipment, Support and Technology Philip Dunne said: “The success of these test flights is an important milestone for the Taranis project. We are gaining vital insights into the potential of unmanned aircraft and this knowledge will shape future capabilities and help reduce the risks faced by military personnel on the frontline. I am determined to continue investing in these world-leading projects to show us the future, today.”

    Speaking on behalf of industry, Nigel Whitehead, our Group Managing Director said: “The first flight of Taranis last year was a significant milestone for UK aviation and this latest development underlines the UK’ s lead in unmanned air systems. The engineering data gathered from the latest phase of trials will help us develop the stealth technologies on Taranis further.”

    Conrad Banks, Rolls-Royce Chief Engineer – Research and Technology, Defence, added: “Successful propulsion integration was another key highlight of the second trial phase, with the fully embedded and ‘hidden’ Adour Mk951 engine operating flawlessly coupled with the highly complex and stealthy exhaust system.”

    in reply to: Eurofighter Typhoon Discussion and News 2014 #2287581
    lukos
    Participant

    I don’t think I’ve ever heard that the UK wanted to use the F-35B for A/G and the Typhoon for A/A, if I did it was most certainly a very long time ago and probably not from a very reliable source. The Typhoon was always planned to have A/G capabilities in RAF service.

    They will likely both be used cooperatively for A2G and A2A.

    Is that new? Eurofighter has been beaten in dog fights by everything from F-16 to F-18 to MiG-29s.

    And the Typhoon has also beaten all of the above in dog fights.

    Look at a dog fight as a football match. Premier League sides get beaten by lower league sides in the FA Cup nearly every year. Does that mean they’re not as good as the lower league sides? No, it just means that the players performed worse on the day.

    in reply to: Military Aviation News-2014 #2287745
    lukos
    Participant

    Taranis demonstrates stealth capabilities in second phase of flight trials

    http://www.baesystems.com/article/BAES_175145/taranis-demonstrates-stealth-capabilities-in-second-phase-of-flight-trials?from=twitter-plc&_afrLoop=361635477912000&_afrWindowMode=0&_afrWindowId=null#%40%3F_afrWindowId%3Dnull%26_afrLoop%3D361635477912000%26from%3Dtwitter-plc%26_afrWindowMode%3D0%26_adf.ctrl-state%3D1a60i1oeqd_1543

    http://www.baesystems.com/cs/groups/public/documents/digitalmedia/mdaw/mtkx/~edisp/~extract/BAES_175152~1~staticrendition/492x277.jpg

    Taranis – the most advanced aircraft ever built by British engineers – flew in a fully ‘stealthy’ configuration, making it virtually invisible to radar during this latest set of trials.

    In order to achieve an unprecedented level of stealth, the team changed all antennas on the aircraft to signature control variants and the air data boom on the nose of Taranis was removed. Following these modifications Taranis used a specially-designed system which allowed the aircraft to generate a full set of flight data, without the use of an external probe or boom.

    Taranis also used a cutting edge communications system to ensure it was able to stay in touch with its mission commander without giving away its position to the enemy.

    Minister for Defence Equipment, Support and Technology Philip Dunne said: “The success of these test flights is an important milestone for the Taranis project. We are gaining vital insights into the potential of unmanned aircraft and this knowledge will shape future capabilities and help reduce the risks faced by military personnel on the frontline. I am determined to continue investing in these world-leading projects to show us the future, today.”

    Speaking on behalf of industry, Nigel Whitehead, our Group Managing Director said: “The first flight of Taranis last year was a significant milestone for UK aviation and this latest development underlines the UK’ s lead in unmanned air systems. The engineering data gathered from the latest phase of trials will help us develop the stealth technologies on Taranis further.”

    Conrad Banks, Rolls-Royce Chief Engineer – Research and Technology, Defence, added: “Successful propulsion integration was another key highlight of the second trial phase, with the fully embedded and ‘hidden’ Adour Mk951 engine operating flawlessly coupled with the highly complex and stealthy exhaust system.”

    in reply to: F-35 News, Multimedia & Discussion thread (3) #2288395
    lukos
    Participant

    Missiles range depends on acceleration time, motor burn time, max speed, drag/aerodynamic efficiency. Who said that missiles max speed is the only factor involved?
    You can have missiles with the same max speed but with the different max range. You can have the missile with higher max speed but with shorter max range compared to slower missile etc. It all depends on what the constructors are trying to achieve.
    I gave you one example where two SRAAM-s with 2,5M max speed and motor burn time of 4,5 to 5,5 sec. can have 30 to 40km max operational range head on and that is the manufacturer claim.

    Max speed as the sole determining factor was implicitly implied by those suggesting a 9s burn time for an AIM-120C7. If a missile only burns for 10-12km but can go for another 110km after that, clearly the burn time is insignificant by their logic.

    I`m not sure I follow you?
    On the videos I posted there is more than clear exhaust plume visible, specially in the case of AIM-9X (there is almost no smoke). It burns and after few seconds it abruptly does not burn any more.

    Yes and the burn time for SRAAMs will be shorter and the acceleration more rapid because that’s the nature of the SRAAM’s task. So the burn time for an AIM-9X may be very short relative to an AIM-120C7, probably many, many times less, rather than half.

    in reply to: F-35 News, Multimedia & Discussion thread (3) #2289162
    lukos
    Participant

    A lot of none**** to stay polite.
    There are many ways to hamper the seeker-head of an AAM. The passive ones are all called stealth. At some distance or against a known threat internal carriage is not in need. The F-35 has an active EW-suit similar to the Rafale and by that the best of both worlds to choose from.

    And because of the stealth it needs less electrical power to employ it effectively.

    in reply to: F-35 News, Multimedia & Discussion thread (3) #2289267
    lukos
    Participant

    Rolling tubes have lift without the drag of large fins. The key is the control of the roll around its center of gravity, to keep the torque forces under control. Large fins are over rated for high altitude steerage.

    The Magnus effect usually involves a cylinder (or sphere) with an axis of rotation perpendicular to the airflow wrt lift, which is what I was talking about as regards staying in level flight whilst unpowered. Some missiles, including the ASRAAM do use body lift more, but missiles using two sets of fins are generally relying on them for lift. The comment regarding lift to weight ratio of SRAAMs vs MRAAMs is a given due to the fact that SRAAMs can generally pull more g even at lower speeds.

    in reply to: F-35 News, Multimedia & Discussion thread (3) #2289300
    lukos
    Participant

    @Sintra: you didnt mark the relevant part in bold, here
    GF5 was a high-speed head-on engagement in excess of 100 km,
    meaning at the time of launch, the supersonic non maneuvering target at high alt was over 100 km away

    http://www.ainonline.com/aviation-news/farnborough-air-show/2012-07-08/theres-no-escaping-mbdas-meteor-missile

    All the targets conducted a final evasive maneuver,” added Bradford.

    GF5 engaged a BQM-167 drone.

    http://www.cei.to/AerialTargetSystems/BQM-167Ai.aspx

    Based on the United States Air Force BQM-167A, CEi’s international variant – the BQM-167i provides world class performance to customers outside the USA in an affordable subscale aerial target. With an operational ceiling greater than 15,000 meters, the BQM-167i enables the international community the capability of testing new weapons systems at altitudes, at speeds and in maneuvering conditions previously unavailable.

    The BQM-167A/i is capable of supporting various mission requirements by carrying a multitude of internal and wing tip mounted payloads as required to best emulate threats as defined by the customer. Payloads include smoke, scoring, IFF, passive and active radar augmentation, electronic countermeasures and infrared (IR) augmentation, including plume pods and internally stored chaff flare dispensing.

    http://www.cei.to/Portals/0/BQM-167A.pdf

    Maximum Speed 0.93 Mach | 308.26 m/s

    Operational Altitude 50ft AGL to 51,000ft MSL
    15.24m AGL to 15,544m MSL

    So it’s more fair to say that given the statement says, “well in excess of 100km,” and the target speed is small relative to the missile, this subscale target was taken out after >100km of flight, whilst it performed an optimal evasive manoeuvre similar to that likely to be used by enemies. Given operational ceiling of target vehicle, this isn’t even a maximum range intercept altitude. Looking back at envelope charts, there likely isn’t even 75% of the range available at this altitude compared to higher launch altitudes and it was against a manoeuvring target.

    http://forum.keypublishing.com/showthread.php?129627-F-35-News-Multimedia-amp-Discussion-thread-(3)&p=2151933#post2151933

Viewing 15 posts - 1,291 through 1,305 (of 1,752 total)