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Thread: Rafale news & discussion part XVI

  1. #2791
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    err, no, it wasnt essentially falling out of the sky, it was perfectly controllable at 70-80 degree AoA
    for as long as fuel and interest last.
    note the dot after the word alpha, in the next sentence he talks about 90 degree per second,
    that could be altered at any given time the pilot wanted,
    but in the previous sentence he was declaring at which AoA it was still fully under control,
    that is, 70-80 degree AoA
    Last edited by obligatory; 19th March 2017 at 16:27.
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  2. #2792
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    Quote Originally Posted by obligatory View Post
    err, no, it wasnt essentially falling out of the sky, it was perfectly controllable at 70-80 degree AoA
    for as long as fuel and interest last
    Reading comprehension...

    A couple clues for you:

    When people are discussing aircraft, a "turn" and a "spin" are very different things.

    ...and one does not "recover" without having departed controlled flight.
    Last edited by hopsalot; 19th March 2017 at 16:35.

  3. #2793
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    Quote Originally Posted by hopsalot View Post
    Of course it does... here is a snippet of an article on those limitations:



    Note, they are talking about recovery from a spin... not controlled flight.



    http://raf-fly.blogspot.com/p/aerody...of-fourth.html

    Note, these are exactly the sorts of test that fanboys misunderstand.

    Flying a Gripen straight up and throttling down until it is essentially falling out of the sky with its nose pointed up don't represent controlled flight or any sort of general capability to operate at those extremely high AoAs.

    What the article is talking about is the Gripen's ability to recover from such a scenario should a pilot be foolish enough to put the jet there. What they are not saying is "the Gripen can be flown at 70-80 degrees AoA," only that if a pilot defeats the AoA limiter in the described manner that the jet can probably recover if enough altitude is available.
    First of all, thx for the read.
    I wasn't sure, but i had a feeling about the Gripen had better control autority to recover vs F-16.
    That goes for the other Euro-Carnards as well.
    But after all they are of newer designs, so not a surprise.


    Note, they are talking about recovery from a spin... not controlled flight.
    I'm not sure what to make of this though..?
    Thanks

  4. #2794
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    Quote Originally Posted by halloweene View Post
    Waoh! time = length/speed Woot! thanks for info. TREst is hot air as usual. (i) inhibition of canard : pure invention. (ii) time lag omgz! i guess DA engineers (not reputable at all when speaking about aerodynamics...) didn't take that into account. (iii) Ok an illusion... Ridiculous.
    Ridiculous, yes it is. Dogmatism never lead R&D toward excellence. Open up. And at least, Saab Swedish Engineer had the guts to name the problem.

    Click image for larger version. 

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    (not the best jpg you can get on google, but Hell no...
    Last edited by TomcatViP; 19th March 2017 at 19:10.

  5. #2795
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    Quote Originally Posted by haavarla View Post
    First of all, thx for the read.
    I wasn't sure, but i had a feeling about the Gripen had better control autority to recover vs F-16.
    That goes for the other Euro-Carnards as well.
    But after all they are of newer designs, so not a surprise.




    I'm not sure what to make of this though..?
    One of the goals of any modern FCS is to keep the aircraft from departing controlled flight (which is why the Gripen has a 26 degree AoA limit). If the pilot finds a way to depart anyway, such as performing the types of maneuvers described in the article about the Gripen testing... then then FCS needs to be able to recover the aircraft.

    Very similar testing to what was described in that article was performed on the F-35, as it was on any other modern fighter. Here you can see some video where the F-35 is briefly falling backwards... (omg! 180 degree AoA!!1!). The problem of course is that the F-35 isn't under control at that moment.

    The whole point is to intentionally put the jet out of control under various different conditions and with various different loads to make sure it can recover if necessary.




    And here is an unintentional departure:




    And another video on depatures:

    Last edited by hopsalot; 19th March 2017 at 19:05.

  6. #2796
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    What really happen to that Gripen?

    The jet looked kind of jerky/iratic before that high alpha.. as if there was some malfunction to the FBW.
    Thanks

  7. #2797
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    Quote Originally Posted by TomcatViP View Post
    Ridiculous, yes it is. Dogmatism never lead R&D toward excellence. Open up. And at least, Saab Swedish Engineer had the guts to name the problem.

    Click image for larger version. 

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    (not the best jpg you can get on google, but Hell no...
    And WHO fixed it for SAAB???

  8. #2798
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    Quote Originally Posted by TomcatViP View Post
    Ridiculous, yes it is. Dogmatism never lead R&D toward excellence. Open up. And at least, Saab Swedish Engineer had the guts to name the problem.

    Click image for larger version. 

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    (not the best jpg you can get on google, but Hell no...
    Once again, nowhere related to Rafale. Where is you clue about inhibition of canard role to control airflow? Stop assessing without any argument, or diverting towards another plane. Kidish. Btw, any video of F-35 controllability at 50° AoA?
    Last edited by halloweene; 19th March 2017 at 21:49.

  9. #2799
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    The F-22 has incorporated its sustained AOA performance into its high AOA pass that it has into its routine. The full envelope F-35 display is not yet cleared but there are some clips from during testing that show some stuff. More once it has a proper routine with full 3F envelope.



    https://www.youtube.com/watch?v=Otp4DaFpyCk
    https://www.youtube.com/watch?v=p3gQjan9StI
    Last edited by bring_it_on; 19th March 2017 at 22:14.
    Old radar types never die; they just phased array

  10. #2800
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    Quote Originally Posted by halloweene View Post
    And WHO fixed it for SAAB???
    The FBW system? It was general dynamics ( then Lockheed martin)I believe.

  11. #2801
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    Quote Originally Posted by Ozair View Post
    The problem is your whole argument is based on a video taken of two Hornets flying one set...
    Actually 95% of the stuff i was talking about is not based on that video, it is only you with your fixsation on the video.

    You have viewed them flying at 30 or less AoA and argue that state is a near constant, claiming that they could have gone higher they would have but didn't.
    No, I have said that most of the time both planes were not going over 30° AoA and I have never stated that this is near constant state. I'll repeat, you are not going to see F-18 hitting 50 deg AoA mark that often simply because the drag at that condition will be to great for plane to have a second go at opponent that can regain energy much better (like Rafale for example). If you miss the chance to put the weapons on the enemy at that condition, most likely you'll be dead afterwards.
    In other words, there is a tight window where you can use that capability and you have to be pretty sure you are getting the job done. You can also use that capability as a last resort when put in to a tight spot.

    And like I said, above 30 deg AoA F-18 has advantage compared to Rafale, but we also have to account enormous part of the fight that comes before you can exploit that part of the flight envelope and that is the part where Rafale has clear advantage.

    You do not know the constraints they were operating under
    No I don't. . .what constraints that might be?

    the type of threat they may have been simulating
    Whatever type of threat they were simulating (if they did?), one plane was in the role of F-18 for sure.

    the respective fuel states
    If I'm not mistaking they were low on the fuel at the end of the third setup.

    any payloads they were carrying.
    Since it is more than obvious that this was classic BFM we can rule out bombs , any kind of air to ground missiles and 3 EFT put together.

    We are left with pilons, air to air missiles and in some case central EFT.
    The addition of pylons to the wing of the Hornet has almost no impact on the high AOA flying qualities. As a matter of fact data for low speed wind tunnel testing F-18 with four pylons mounted on the inboard and outboard wing stations indicates that the aircraft is more stable with pylons than without pylons. Low speed results in the 30 to 50 deg AOA range show approximately a 15 % increase in departure resistance with carriage of four pylons when compared to the clean aircraft.
    Flight test including high AOA flying qualities and departure resistance testing in the attack training configuration with wingtip stores, pylons and VERs on
    four wing stations, fuselage missiles and a centerline fuel tank showed that defensive high g barrel rolls in the attack training configuration were easily performed with no problem controlling yaw rate.
    It is also interesting to note that test results indicated that removing wingtip missiles and launchers slightly reduced longitudinal stability and lateral stability
    below 42 deg AOA.

    Long story short, there is extremely low (almost non existent) probability that you can use some kind of air to air payload that will limit the Hornet to 30 deg AoA.
    Even if they put the weapons during BFM, that would only be more realistic representation of the capabilities for F-18 within visual range fight.

    The same applies for the SU-35 demo.
    According to test pilots the amount of fuel they most often use for the demo is in the range of 4,5 to 5 tones. Putting few air to air missiles has almost no impact on high AoA capabilities of the plane.

    Attempting to extrapolate what you have from those videos without knowing the above is in error. You do not have enough information to make the claims you are making.
    I'm not doing that, you are the one trying to make me look like I'm doing that.
    I used the video only as a simple example to point out that F-18 pilots are not hitting its AoA limits that often. Nothing more, nothing less. And that is not the only video of F-18 HUD, there are many more with similar trend.

  12. #2802
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    Thumbs up

    Quote Originally Posted by TomcatViP View Post
    I am on it 100%. Glad we finally reach a gentle agreement.
    Cheers!

  13. #2803
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    Quote Originally Posted by Ozair View Post
    Obviously there are a number of factors that influence the above but WVR has moved from what Gums spoke about with high sustained turn rates to high instantaneous turn rates and high AoA to get that first shot opportunity (in the highly unlikely event that the fight ever gets that close).
    This trend started well before off-boresight missiles were a "thing", as the advances in missile design and seeker technology made "snap shots" possible, whereas older type missiles required very exact launch parameters. To lesser extent same is true with guns, automated gun modes opening more opportunies for pilot to get a shot.

  14. #2804
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    Quote Originally Posted by TomcatViP View Post
    Active flows ctrl does not necessarily involves moving a surface in the airstream. I won't also qualify the LEVCON or nose strake as an active flow ctrl meaning. The Levcon is a an additional moving surface and the nose strakes are flap that ctrl the vortex.
    Active flow is more a meaning to ctrl and actuate the property of the flow by itself. Keeping it laminar for example, modifying the apparent pressure loss around a surface etc... It's way more sophisticated in the sense that it target directly what makes drag and lift. As a comparison, it's like figuring what are the differences b/w penicillin and an amputation.
    Are you talking about boundary layer suction? In the '90s I heard about designers trying these techniques in sailplanes but seems that not much progress has been made yet. All the references of "active flow control" I found regarding F-35 seem to concern inlet flow, and potentially exhausts, not aerodynamic surfaces.
    If this technology was something which was already applied to basic Hornet as you claimed, seems strange that Dassault hadn't heard about it decade later.

  15. #2805
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    Quote Originally Posted by Yama View Post
    Are you talking about boundary layer suction? In the '90s I heard about designers trying these techniques in sailplanes but seems that not much progress has been made yet. All the references of "active flow control" I found regarding F-35 seem to concern inlet flow, and potentially exhausts, not aerodynamic surfaces.
    If this technology was something which was already applied to basic Hornet as you claimed, seems strange that Dassault hadn't heard about it decade later.
    He is trying to BS himself out of the corner he got himself in. Cryptic half sentences & graphs showing god knows what coupled with his reluctance to put up a coherent argumentation prove it.

    Ce qui se conçoit bien s'énonce clairement.

  16. #2806
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    Quote Originally Posted by FBW View Post
    The FBW system? It was general dynamics ( then Lockheed martin)I believe.
    NO

  17. #2807
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    I remember that in one of the first rafale deployement in 2001 Rafale M F1 did quite a lot of BFM maneuvres against F14 and Hornets. Rafale pilots reports at the time said the the F14s were no match against the rafale but it took a little longer against the Hornet but eventually had the upper hand due to rafale performance.
    If I recall well there is also an early "fox three" relating the performance of the rafale vs mirage 2000 and F16 describing how it is superior to both of them during BFM.

    Although BFM is no longer the metric of how a fighter jets would perform in a modern air warfare, there is little doubt that it is among the very best in this regard.

    Beyhond this issue, I am still very skeptickal about F35 maneuvrability despite the PR offensive. I have yet to see it perform a simple loop, a sucession of barrel roll without sinking and a proper demo in the range of what most other modern fighter can do and as every one as already seen for years. F35 supporters will jump on me for sure but I can't help thinking that such a fat jet with its high fuel fraction and internal bays will suffer against older but sleeker designs. I know there are reports saying the contrary, body lifts etc...But I am still not convinced. If it was so maneuvrable, why not showcasing it during RIAT or any kind of airshows ? I mean even civilian aircrafts like the A380 and 787 are doing impressive demos within their class while being civilian aircrafts. Now I am no F35 hatter, I firmly belive that it brings unmatched SA and stealth to the battlefield and I would definitly choose an F35 if I add to go in a high threat environement. Just that I don't belive it is a very maneuvrable jet...It's ok for a tactical fighter bomber but nothing exptionnal.

    I believe such high AoA could be achieved in most jets but it is a choice from the manufacturer to go beyhond a certain point. If you have very high AoA but then you are sinking like a brick I am not sure it is that usefull. And when I see a formation of a F35 and F16, the F35 struggle with higher AoA than the F16 for instance.

  18. #2808
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    I believe such high AoA could be achieved in most jets but it is a choice from the manufacturer to go beyhond a certain point. If you have very high AoA but then you are sinking like a brick I am not sure it is that usefull. And when I see a formation of a F35 and F16, the F35 struggle with higher AoA than the F16 for instance.
    High AoA for a brief period will certainly bleed energy but you don't sink like a brick immediately. At lower speeds, the capability to momentarily reach a high angle of attack in turns to bring the nose around trading energy for rate is especially important. The AoA limited aircraft may compete a 360* turn with more energy, but does cannot trade energy for higher rate of turn at the limit.

    two studies that have been posted here quite a few times (page 6 of the first is pointing margin metric)
    http://citeseerx.ist.psu.edu/viewdoc...=rep1&type=pdf
    https://ntrs.nasa.gov/archive/nasa/c...9900014070.pdf

    For the last part, the F-16 and F-35 have different flap schedules at low speed. Your looking at the nose to determine that the F-35 is flying at a higher AoA, the flaps change the angle of attack of the wing. Click image for larger version. 

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    They have different control laws, The F-35 doesn't have LEF/TEF set at the same angle. The F-35's horizontal stabs are set postive AoA (they provide lift), the F-16's are set down (negative AoA creating drag), this counteracts positive wing AoA and keeps nose level. If the nose up flight of the F-35 was draggier than the trim drag created by negative position of the stabilators, they would change it.

    Sorry for the OT, but it does go with the conversation over angles of attack ongoing in the Rafale thread.
    Last edited by FBW; 20th March 2017 at 13:33.

  19. #2809
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    Quote Originally Posted by halloweene View Post
    Once again, nowhere related to Rafale. Where is you clue about inhibition of canard role to control airflow? Stop assessing without any argument, or diverting towards another plane. Kidish. Btw, any video of F-35 controllability at 50° AoA?
    Kiddish ? Stop the insult for once.

    Already discussed, posted, noted, commented... And yes, the FCS laws has been altered on the Rafale. I even discussed a video someone here posted with the HUD view very explicitly showing where the roll limiter inhibited totally the plane until AoA was lowered.

    I would suggest you use the time you devote to insult other online to learn how to use the search function on this forum. .

    any video of F-35 controllability at 50° AoA
    You know the test report that you was so happy a while ago to post every once in a while. It says it all. Remember the pedal turn?

  20. #2810
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    Quote Originally Posted by Nicolas10 View Post

    Ce qui se conçoit bien s'énonce clairement.
    LOl. excellent.

    "L'éloquence n'est que l'art d'embellir la logique." I am a fan I have to admit

  21. #2811
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    Quote Originally Posted by FBW View Post
    High AoA for a brief period will certainly bleed energy but you don't sink like a brick immediately.
    Right so you fall like a flat iron & not like a brick. Then you can iron the Rafale's pilot's shirt, b*[$#.

  22. #2812
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    Quote Originally Posted by TomcatViP View Post
    LOl. excellent.

    "L'éloquence n'est que l'art d'embellir la logique." I am a fan I have to admit
    That's not all you have to admit though.

  23. #2813
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    Quote Originally Posted by Nicolas10 View Post
    That's not all you have to admit though.
    ?!
    Did I play Mr doctor with you when we were kids? Please tell me not.

    He is trying to BS himself out of the corner he got himself in. Cryptic half sentences & graphs showing god knows what coupled with his reluctance to put up a coherent argumentation prove it.
    No. I even got the reader on the trail : where the awareness came from (the graph are from a rotary wing), what kind of plane might immediately benefit from one the straightforward application and left some mark for where to start reading if interested.


    Now this conversation is over. I don't have the time, will and tools at immediate hand reach to edit the video that I would need in order to compose a synthesis of what has been done already. Scroll back, browse or search the forum. Thanks.
    Last edited by TomcatViP; 20th March 2017 at 19:46.

  24. #2814
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    Quote Originally Posted by Nicolas10 View Post
    Right so you fall like a flat iron & not like a brick. Then you can iron the Rafale's pilot's shirt, b*[$#.
    Doesn't read studies posted or understand the concept being explained, chimes in with irrevelant cheerleading of national fighter program.

    Ignorance and arrogance are a poor substitute for intelligent, fact based discussion and critique.

  25. #2815
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    Quote Originally Posted by Nicolas10 View Post
    Right so you fall like a flat iron & not like a brick. Then you can iron the Rafale's pilot's shirt, b*[$#.
    Well, you are certainly making a point... though not the one you are shooting for I think.

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    Belgium has decided to go ahead with the procurement of 34 new fighters to replace its 54 F-16s. In the running is the Dassault Rafale, SH, Gripen E/F, F-35A and the Typhoon. But the budget being set aside for the procurement ($3.4 billion) would seem to be unrealistically low, considering recent sales for European aircraft. Perhaps only the Gripen E/F and Super Hornet would be able to somehow meet the current procurement budget.

    What is the buzz in France about this deal? Do they consider the chances of a sale for the Rafale to be good? Given India's 36 unit order for Rafales and some armaments, that cost it $8.8 billion, it would seem the Rafale is unaffordable for Belgium.

  27. #2817
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    Quote Originally Posted by BlackArcher View Post
    Belgium has decided to go ahead with the procurement of 34 new fighters to replace its 54 F-16s. In the running is the Dassault Rafale, SH, Gripen E/F, F-35A and the Typhoon. But the budget being set aside for the procurement ($3.4 billion) would seem to be unrealistically low, considering recent sales for European aircraft. Perhaps only the Gripen E/F and Super Hornet would be able to somehow meet the current procurement budget.

    What is the buzz in France about this deal? Do they consider the chances of a sale for the Rafale to be good? Given India's 36 unit order for Rafales and some armaments, that cost it $8.8 billion, it would seem the Rafale is unaffordable for Belgium.
    It is out of the question that they will be able to buy any modern aircraft in those numbers with that budget.

    Even the Gripen deal with Switzerland was $3.4 billion for 22 aircraft. The eventual contract with Brazil was 36 aircraft for $4.68 billion.

  28. #2818
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    It's an accounting trick similar to Denmark's: they buy only the planes (F-35's), not any spares or armament.

  29. #2819
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    3400/34=100M$/plane

  30. #2820
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    Quote Originally Posted by TomcatViP View Post
    3400/34=100M$/plane
    That will be tough to do for program acquisition cost. They'll have to increase the topline, reduce the number or buy in phases. Canada's Super Hornet FMS announcement when it comes will be an interesting $ # to look at.
    Old radar types never die; they just phased array

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