Key.Aero Network
Register Free

Page 65 of 67 FirstFirst ... 155561626364656667 LastLast
Results 1,921 to 1,950 of 1981

Thread: Eurofighter Typhoon discussion and news 2015

  1. #1921
    Join Date
    Jun 2004
    Location
    Columbia, MD
    Posts
    11,527
    Doubt there will be any customer for these looking at the Italians' attempt to offload their T1 Typhoons.
    One could always dream - http://www.drakenintl.com
    Old radar types never die; they just phased array

  2. #1922
    Join Date
    Jan 2012
    Posts
    3,151
    SAAB was using C-7 at this date.

    AMRAAM AIM-120C-5 entered service in 2000.
    In a 2015 issue of "revue des ingénieurs de l'armement" they still stated 3 times the NEZ of anyother AA missile in service.

  3. #1923
    Join Date
    Jan 2009
    Posts
    4,440
    They have been saying the "3x the NEZ" from the very beginning.

    The direct quote is "Meteor has an NEZ 3x greater than the AMRAAM that it was designed to replace". That was the AIM-120B.. not the C or anything newer.

    Name:  oVxCFj2.jpg
Views: 971
Size:  364.7 KB
    "The early bird gets the worm but the second mouse gets the cheese."

  4. #1924
    Join Date
    Jan 2012
    Posts
    3,151
    The direct quote is "Meteor has an NEZ 3x greater than the AMRAAM that it was designed to replace". That was the AIM-120B.. not the C or anything newer.
    NO. I am explcitely talking about a MBDA engineer talking to other engineer in 2015. http://fr.calameo.com/read/0000097790970dadaed3c p39
    min 3xNEZ vs any in service armament.
    Last edited by halloweene; 9th July 2017 at 17:17.

  5. #1925
    Join Date
    Jul 2005
    Posts
    4,439
    At the end of the day this circle running discussion about 3 x times NEZ vs other AAMs is somewhat moot. Why? Because no one here knows the relevant performance characteristics of all these weapons, neither do MBDA engineers know all facts about a Raytheon product and vice versa. It may be true or not. That the Meteor's propulsion system is unique among BVRAAMs in service today is undisputable and that the characteristics of the different propulsion systems have particular merits of each own is true as well. Argueing about public statements made by "officials" and declaring them to be the universal truth is somewhat ignorant, but of course it's the best average joe can argue on. There are certainly more factors that matter when it comes to the overall effectiviness and performance of a particular weapon system.

  6. #1926
    Join Date
    Dec 2008
    Location
    Norway
    Posts
    5,851
    Agree Scorp. Wasn't there a general agreement that true NEZ is measured in Volume of airspace rather that any range?
    Thanks

  7. #1927
    Join Date
    Jul 2005
    Posts
    4,439
    NEZ is a dynamic value, not a constant one. NEZ means what it says. It's essentially the distance at which a target can't do a U-turn and run away, which certainly depends on the targets turning and acceleration capability, which itself is dependent on its speed, altitude, weight and loadout, engagement geometry, flight conditions of the launch platform and ofcourse missile performance which is linked to the above conditions.

  8. #1928
    Join Date
    Dec 2008
    Location
    Norway
    Posts
    5,851
    So what are we talking about.. does the MBDA mean to pick the 120A with a lot of offset flight condition or do they really mean to claim the Meteor has 3 times flight range over 120B or C model??

    What i meant by NEZ Volume is pretty straight forward. Its the Volume of Space in any direction from the jet that the missile could teoretical cover or reach when launched. I once saw a nice illustration over this, the airspace Volume behind of the jet would be much less vs in the frontal hemisphere.


    Ofcourse it a dynamic figure depending on Lots of parameters.
    What is the maximum launch/seperation speed of EF?

    But when you increase the range or flight time of a missile, you increase the NEZ Volume exponential.. just saying.

    I have a very hard time believe it has 3x range over 120C as it is.

    And b.t.w. where does it explicit state that No Escape Zone is measured in distance from point A to B rather than in Volume?
    Last edited by haavarla; 10th July 2017 at 22:16.
    Thanks

  9. #1929
    Join Date
    Jan 2009
    Posts
    4,440
    The key lies in their own quote "three times the NEZ of the missile it was designed to replace".

    When the goals & specs for the Meteor were laid down, the only AMRAAM in operational European use was the AIM-120B. Therefore, logic says that if you set the "3x NEZ spec" based on the only AMRAAM you were using (the B) then it is the B that your "3x NEZ" is based on.

    This is of course all IMHO.
    "The early bird gets the worm but the second mouse gets the cheese."

  10. #1930
    Join Date
    Oct 2015
    Posts
    649
    What i meant by NEZ Volume is pretty straight forward. Its the Volume of Space in any direction from the jet that the missile could teoretical cover or reach when launched.
    That is not what NEZ means and Scorpion82 had a clear and correct definition. NEZ is No Escape Zone which is the zone at which a missile kinematically cannot be defeated by the target aircraft, ie the target aircraft cannot flow cold and defeat the missile by denying an intercept. An intercept will occur so the target aircraft will have to defeat the missile through evasion/ECM/DIRCM etc.

    And b.t.w. where does it explicit state that No Escape Zone is measured in distance from point A to B rather than in Volume?
    The western fighter community doesn't talk about NEZ volume, just NEZ. The volume side of it is implicit in the description.

  11. #1931
    Join Date
    Jun 2004
    Location
    Columbia, MD
    Posts
    11,527
    In pubished literature the first mention of No Escape Zone/Envelope was introduced by Shinar and Gazit in their 1985 paper presented at an AIAA confrence:

    It has become clear that the true measure of missile effectiveness is a firing envelope which guarantees a successful interception against any feasible target maneuver This statement serves in fact as the definition of a “no-escape” firing envelope The concept has been acknowledged by many aircraft and missile designers, but has not yet been discussed or analyzed in the open technical literature. ~ Joseph Shinar, R Gazit, "Optimal 'no-escape' firing envelopes of guided missiles", AIAA
    Adding further to this research Werner Grimm and Joseph Schaeffer of the Institute of Flight Systems Dynamics concluded :

    In this paper "optimal launch conditions on the no-escape envelope" are presented, which are characterized by two proper-
    ties:
    (i) They guarantee a hit of the target.
    (ii) The range at launch time is maxi- mized with respect to some state
    variables at launch time.
    (iii) leads us to the boundary of the firing envelope. It is called "no-escape envelope", since a near optimal avoidance maneuver of the target is assumed.
    Great emphasis is put on realistic models. A target strategy is constructed, which
    - resembles the typical behaviour of an aggressive pilot,
    - approximates the optimal avoidance maneuver in the terminal phase and
    - monitors the performance limits of the aircraft, which is itself a careful approximation of an existing fighter aircraft.

    Therefore, the basic trends observed in the solutions are of practical value. The main observation concerns the altitude at the instant of missile firing. For a given amount of energy at launch time an altitude advantage is more important than high speed. The missile launch takes place at high altitude with a flight path angle distinctly above LOS-direction.
    Last edited by bring_it_on; 11th July 2017 at 01:05.
    Old radar types never die; they just phased array

  12. #1932
    Join Date
    Feb 2009
    Posts
    369
    I have a very hard time believe it has 3x range over 120C as it is.
    The AIM-120C7 & beyond reach their impressive ranges through the use of a longer initial burn combined with highly lofted trajectories - the peak altitude is much higher, the associated low air density and drag helping increase the max range tremendously.

    It's far from given that their NEZ has increased as much as the maximum range, in a low arc trajectory the extra energy from the longer burn time is mostly wasted. I wouldn't be surprised if the 2.5x max range increase only translated in ~1.4x extra NEZ (that's my best guesstimate based on public data).

    The problem is that the NEZ depends on the engagement configuration, there is no simple number so that leaves a lot of space for people who want to argue in bad faith.

  13. #1933
    Join Date
    Jan 2009
    Posts
    4,440
    The nice thing about a lofted flight profile (especially a GPS aided one like the AIM-120D's) is that the endgame is prosecuted with the aide of gravity rather than fighting gravity like a traditional, strait-on shot.
    "The early bird gets the worm but the second mouse gets the cheese."

  14. #1934
    Join Date
    Jun 2005
    Location
    Cemetery Junction
    Posts
    13,420
    Yeah. What sort of profile do you think Meteor uses?

    I'm old enough to recall the Sea Dart SAM getting an increased range through the adoption of a lofted profile. It's not exactly something new.
    Juris praecepta sunt haec: honeste vivere, alterum non laedere, suum cuique tribuere.
    Justinian

  15. #1935
    Join Date
    Jan 2009
    Posts
    4,440
    Given that the Meteor is a fixed inlet air breather with a one-way datalink & non-GPS INS, it stays relatively low.
    "The early bird gets the worm but the second mouse gets the cheese."

  16. #1936
    Join Date
    Nov 2011
    Location
    "Where the fruit is"
    Posts
    4,318
    That depends of the designed mass-flow of the inlet, hence speed. For what we know (mach), it must fly lower and face greater drag on overall.
    I think I wrote this already some times ago.

    But for sure launcher and target speed, alt and aspect ratio dictate so much the NEZ size that there might be a configuration where one triple the second... and Vice versa
    Last edited by TomcatViP; 11th July 2017 at 15:12.

  17. #1937
    Join Date
    May 2005
    Posts
    4,362
    Converting altitude vs speed gives end-game maneuvering agility to older missiles, but it's a moot point here since the meteor is powered during the endgame.

    Nice strawman tho.

  18. #1938
    Join Date
    Aug 2007
    Posts
    3,439
    Given that the Meteor is a fixed inlet air breather with a one-way datalink & non-GPS INS, it stays relatively low.
    It has a two way datalink, it uses a variable internal duct, its flight profile acording to severall MBDA public documents is freakingly high by comparison with its ancestor (the Matra MICA) and the GPS thingy is interestingly absent from the likes of the Standard SM2 and its being introduced in the SM6 for the anti land role.
    Last edited by Sintra; 11th July 2017 at 16:45.

  19. #1939
    Join Date
    Feb 2013
    Posts
    217
    And powered flight at the end of engagement that is where meteor gains its increase in no escape zone. Not from total range as compared to amraam. But by meteor having powered flight at the end of a engagement. It's not something the amraam has the ability to match or close no matter what version of it we are talking about.
    Last edited by Siddar; 11th July 2017 at 16:48.

  20. #1940
    Join Date
    Jan 2009
    Posts
    4,440
    GPS would do little good for the SM2 since it is a SAR seeker thereby it's getting constant updates from the ship.

    The original SM6 is based on AIM-102C7's seeker since the D was not available at the time so it did not have GPS.

    SM–6 Blk1 has GPS for BVR & OTH shots.
    "The early bird gets the worm but the second mouse gets the cheese."

  21. #1941
    Join Date
    Aug 2007
    Posts
    3,439
    Quote Originally Posted by SpudmanWP View Post
    GPS would do little good for the SM2 since it is a SAR seeker thereby it's getting constant updates from the ship.

    The original SM6 is based on AIM-102C7's seeker since the D was not available at the time so it did not have GPS.

    SM–6 Blk1 has GPS for BVR & OTH shots.
    And an missile with an active head receives constant updates from its own radar instead of an offboard sensor, what has that to do with the GPS data is anyones guess...
    And what GPS has to do with the flight profile of an AAM is even more esoteric...
    But yes, the Meteor does have a two way datalink, it uses lofted flight profiles, and so on.

  22. #1942
    Join Date
    Jan 2009
    Posts
    4,440
    The seeker & battery of an active AAM are too small to prosecute guidance over it's entire BVR range, which is why all BVR missiles have datalinks to begin with.

    Historically the gyro-based INS is used to guide the AAM to the killbox in order for the AAM's seeker to obtain a lock. During the flight, the datalink can be used to update the target's last known position. However, because the INS is based on a gyro, that introduces errors that get worse as the range get's longer and the flight profile get's more complex.

    A GPS assisted INS removes these potential errors so that the AAM knows exactly where it is, exactly where the enemy is, and exactly what velocity the target is on in order to setup the best interception possible.
    "The early bird gets the worm but the second mouse gets the cheese."

  23. #1943
    Join Date
    Aug 2007
    Posts
    3,439
    The seeker & battery of an active AAM are too small to prosecute guidance over it's entire BVR range, which is why all BVR missiles have datalinks to begin with.

    Historically the gyro-based INS is used to guide the AAM to the killbox in order for the AAM's seeker to obtain a lock. During the flight, the datalink can be used to update the target's last known position. However, because the INS is based on a gyro, that introduces errors that get worse as the range get's longer and the flight profile get's more complex.

    A GPS assisted INS removes these potential errors so that the AAM knows exactly where it is, exactly where the enemy is, and exactly what velocity the target is on in order to setup the best interception possible.
    Obviously i wasnt clear, my bad. My point was, having GPS has absolutely no bearing on the altitude that the AAM autopilot chooses to fly, its not because it doesnt have an integrated GPS that a Meteor will fly lower than a AIM-120D.

  24. #1944
    Join Date
    Jun 2004
    Location
    Columbia, MD
    Posts
    11,527
    Sintra, the guidance upgrades on the SM61A were planned with many things in mind including its performance in the long range AAW and BMD missions. It as you rightly point out also opens up the Surface Attack role.

    On the Aim-120D, the range increase from the C7 has been described by Raytheon as "low double digit percentage".
    Last edited by bring_it_on; 11th July 2017 at 18:32.
    Old radar types never die; they just phased array

  25. #1945
    Join Date
    Jul 2005
    Posts
    4,439
    Spud, given the rather limited flight time of AAMs the INS error is pretty small. I doubt that there is a significant difference here as the TOF is measured in seconds or maybe 2-3 minutes at best, not hours. Furthermore GPS gives your missile a velocity as does INS btw, but target velocity is not obtained through GPS but MCG from tje guiding platform.

  26. #1946
    Join Date
    Jan 2009
    Posts
    4,440
    GPS has absolutely no bearing on the altitude that the AAM autopilot chooses to fly
    Every change in direction that a gyro-based INS makes introduces errors which add up to a greater miss chance in the end.

    With a GPS-based INS there are no errors so the AAM can fly whatever profile it wants to since it can make a more accurate attack plan. This was covered in detail during the AIM-120D development as a prime driver for the D's increased range & NEZ vs the C7.
    "The early bird gets the worm but the second mouse gets the cheese."

  27. #1947
    Join Date
    Jan 2009
    Posts
    4,440
    Spud, given the rather limited flight time of AAMs the INS error is pretty small.
    Given that AAMs can reach out to near 100nm, even a small error can keep the AAM from reaching the reletively small killbox where it's seeker can achieve a lock. Throw in jamming and the AAM has to get even closer to "burn through" the jaming.

    Furthermore GPS gives your missile a velocity as does INS btw, but target velocity is not obtained through GPS but MCG from tje guiding platform.
    The target's precise GPS location & velocity are provided via datalink. As I said, GPS removes all accumulated INS errors and even helps with jamming.
    "The early bird gets the worm but the second mouse gets the cheese."

  28. #1948
    Join Date
    Feb 2012
    Posts
    219
    Me thinking that the inaccuracy drift on a missile fully powered in the end game is much less of an issue compared to a non powered missile at terminal velocity. After traveling 200 km at MACH 4 we are talking around 50 meters inaccuracy with recent INS.
    Not sure how GPS would help with jamming as it is likely GPS signal being the first thing being jammed compared to INS less accurate but that can not be jammed

  29. #1949
    Join Date
    Jan 2009
    Posts
    4,440
    Meteor does not cruise at Mach 4 out to 200km.

    GPS helps with jamming because it can be updated with the target's precise GPS location from multiple off-board assets (if available) which can allow the AAM to get much closer to the true target in order for it's own seeker to burn through the jamming.
    "The early bird gets the worm but the second mouse gets the cheese."

  30. #1950
    Join Date
    Nov 2011
    Location
    "Where the fruit is"
    Posts
    4,318
    INS drift is aggravated by the accelerations.

Thread Information

Users Browsing this Thread

There are currently 2 users browsing this thread. (0 members and 2 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

- Part of the    Network -

KEY AERO AVIATION NEWS

MAGAZINES

AVIATION FORUM

SHOP

 

WEBSITES