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SAAB Gripen and Gripen NG thread #4

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  • obligatory
    Senior Member
    • Oct 2008
    • 7043

    Originally posted by Spitfire9 View Post
    obligatory answered my question well enough. Just wanted some guidance. That is what I got. The deltas - Gripen, Typhoon (and presumably Rafale) - appear more favourably shaped for lower supersonic speed transonic drag reduction. I wonder if they win on subsonic transonic drag, too.
    yes, it both delay transonic region and end it earlier,
    an F-35 would be stuck in transonic from ~M0.8 -M1.2+
    while gripen encounter a small jump from M0.95-M1.05,
    or thereabout.

    the chief designer of gripen suggest a tail configuration improve range at cruise speed,
    at least with the info & tech that was available when gripen was designed.
    Gripen analyzed

    The choice of configuration, canard or tail, was far from obvious, initially.
    A substantial body of knowledge existed on the delta canard layout,
    gained from Viggen experience of course, but that was not entirely favourable for such a solution.

    The drawbacks as well as the good features were evident.
    A sometimes heated debate on this topic had been going on inside the Swedish aeronautical community for years.
    Wind tunnel testing and project work on alternative aft tailed configurations had pointed out many advantages for that particular layout,
    where perhaps range and sustained turn rate were the most noticeable, granted the technological level of that time.
    http://www.mach-flyg.com/utg80/80jas_uc.html
    Last edited by obligatory; 9th February 2016, 00:56.

    Comment

    • moon_light
      Rank 5 Registered User
      • May 2012
      • 1029

      Originally posted by obligatory View Post
      how long a fighter will remain in transonic is very different from fighter to fighter,
      depending on wing sweep, area distribution, wing thickness, etc,
      deltas are as built for transonic, out of current fighters, gripen is hard to beat, only competition being possibly EF,
      F-16 exit around M1.15, gripen & EF around M1.05, F-35 somewhere after M1.2
      http://history.nasa.gov/SP-367/f91.htm
      http://history.nasa.gov/SP-367/chapt5.htm
      can you explain in more detail on how did you come up with the conclusion ?
      the picture seem to indicate that drag start to reduce right after the mach barrier for all kind of wing

      airfoil thickness seem to play a part too

      Comment

      • hopsalot
        Senior Member
        • Aug 2012
        • 3166

        The mission of Wednesday, August 13, 2008, however, promised to be simple. A plane flies north towards the Alps of Ticino and is the intercept. To do this, the evaluation team placed the Gripen D 39-822 registered on alert on the military base of Zion. The tarmac is dry, it's beautiful weather. At the controls of the fighter, the Swiss test pilot Peter Merz, aka "Pablo" behind him, the Saab Gripen manufacturer, to ensure that everything goes smoothly. After taking off as planned at 15 h 32, the plane goes into Swedish supersonic speed to stabilize at Mach 1.42. But suddenly, in the middle of his approach: "Bingo Fuel"! The LED Alarm fuel placed on the left of the cockpit shows the need to abort the mission and return to base.

        Gripen arrived barely in contact with the F/A-18 to intercept, but was unable to intervene and had to land in Emmen (LU). Ground, the head of the Swiss Air Force Markus Gygax is stunned: excluded to buy such a flying pan. In comparison, the French Rafale, tested under the same conditions two months later, has made the interception, returned to Zion, and has been able to achieve another successful missions. On the twenty-six test flights at the time by the Gripen, the plane landed with four times the reserves of fuel below the minimum security.
        http://www.lematin.ch/suisse/suisse-...story/25116550

        Translated here: http://forum.keypublishing.com/showt...04#post1890004

        Comment

        • maurobaggio
          Rank 5 Registered User
          • Jul 2008
          • 521

          The F/A 18E/F and Gripen E has been keeping several aspects in common, since both were developed from fighters already in production (F/A 18 and Gripen), as well as it has been share the same engine F414 (2XF/A 18E/F and 1XGripen E).

          Despite this last similarity regarding the engine F414, the F/A 18E/F and the Gripen and has two major differences about this:
          • the F/A 18E/F made its first flight in 1995, while the Gripen E will make it first flight in 2016, then 21 years after the F/A 18E/F, or in the case of the Gripen Demo about 13 years;
          • the F414 engine in the Gripen NG were the Plan B, while the F/A 18E/F the F414 engine had been developed specifically for it.



          Once the original plan( Plan A) for the Gripen NG were the engine EJ200 with vectoring thrust, but with the cancellation the last, it were adopted the F414.

          After all with the F414 has been already available in reason of the F/A 18E/F since the middle 90's, in fact it could be even more safety and less expensive to choose the F414 instead of a new project that were in its design phase, such as the EJ200.


          I have been keeping these doubts for years, but it could be resumed in this question: if the engine F414 does wonders for the Gripen NG, why it has been awaiting for 21 years to implement this?

          Comment

          • FBW
            FBW
            Rank 5 Registered User
            • Dec 2011
            • 3295

            Originally posted by obligatory View Post
            yes, it both delay transonic region and end it earlier,
            an F-35 would be stuck in transonic from ~M0.8 -M1.2+
            while gripen encounter a small jump from M0.95-M1.05,
            or thereabout.

            the chief designer of gripen suggest a tail configuration improve range at cruise speed,
            at least with the info & tech that was available when gripen was designed.

            http://www.mach-flyg.com/utg80/80jas_uc.html

            You can keep on posting this tripe, but it is inaccurate and typical of Obligatory posts. It is long on conjecture and short on facts. You don't have to respond, your M.O. is well established on the forum. So, the Gripen clears the majority of transonic wave drag by mach 1.05? Are you going to stick with this? I won't ask you for how you came to this conclusion as I already know.

            Just out of morbid curiosity, I would like to know how you calculate the transonic regime for the F-35 though. Wait, quick guess a NACA chart on wing sweep?

            Comment

            • FBW
              FBW
              Rank 5 Registered User
              • Dec 2011
              • 3295

              Originally posted by moon_light View Post
              can you explain in more detail on how did you come up with the conclusion ?
              the picture seem to indicate that drag start to reduce right after the mach barrier for all kind of wing

              airfoil thickness seem to play a part too
              No, look at the drag coefficient on the Y axis. Wing sweep/ very thin wings was crucial for early fighters to achieve supersonic speeds vs. traditional straight or moderate sweep wings (et ceteris paribus). For the first generation of supersonic fighters, to overcome wave drag, wing sweep allowed for a lower aspect ratio and higher critical mach numbers. Interestingly, MOST modern fighter since the century series have strayed from the simplistic formula of highly swept wings and "coke bottle" area ruling. The combination of: higher thrust engines, the need for a wing to perform well across speed regimes, different root and tip chords, supercritical wings, and better modeling of fluid dynamics have led to modern fighters looking very different from the first and second generation of supersonic fighters.
              Last edited by FBW; 9th February 2016, 04:17.

              Comment

              • Halo
                Rank 5 Registered User
                • Apr 2009
                • 212

                Originally posted by maurobaggio View Post
                Once the original plan( Plan A) for the Gripen NG were the engine EJ200 with vectoring thrust, but with the cancellation the last, it were adopted the F414.

                After all with the F414 has been already available in reason of the F/A 18E/F since the middle 90's, in fact it could be even more safety and less expensive to choose the F414 instead of a new project that were in its design phase, such as the EJ200.


                I have been keeping these doubts for years, but it could be resumed in this question: if the engine F414 does wonders for the Gripen NG, why it has been awaiting for 21 years to implement this?
                ....??!?!?!??
                Well, back to the very basics, Gripen A was designed for an environment where it was supposed to meet a huge number of soviet aircraft that had to cross the Baltic. Gripen would operate from many small dispersed bases. Due to the large number of bases and that Gripen would fight a lot closer to home base than the enemy so the need for fuel was't that big. As Urban has enforced, if you start to take on extra size or weight it has to be compensated for that would start a vicious circle, the Gripen was all about breaking this cycle. Due to these very obvious reasons Gripen A did't need the extra fuel, weapons or a larger engine. In the post 1st Cold war era the number of planes and bases was significantly reduced and the type of missions became wider so there was a need to adjust the design targets if the aircraft.... Designers are not stupid, the do tend to optimize the design.. If you would like to go max afterburner (CH) and or carry heavy loads long distances.... dont go for Gripen A-D and certainly the E/F will never "shine" here either!

                Comment

                • obligatory
                  Senior Member
                  • Oct 2008
                  • 7043

                  from all the reading i've done on gripen NG,
                  EJ200 was never the frontrunner, it was presented as a backup alternative.

                  the wonder with NG is increased fuel fraction IMO, an engine upgrade is merely needed to keep performance on pair,
                  the real question is why SAAB, AF, & Gov. didnt halt gripen C when it was no longer any particular hurry,
                  and re-configure into the present E model

                  Comment

                  • MSphere
                    Senior Member
                    • Feb 2010
                    • 8983

                    Originally posted by hopsalot View Post
                    Yep, that's the one.. But now you need to account for fuel differences from Gripen D --> Gripen C and then from Gripen C --> Gripen E.

                    Comment

                    • Sintra
                      Rank 5 Registered User
                      • Aug 2007
                      • 3849

                      Originally posted by maurobaggio View Post
                      Once the original plan( Plan A) for the Gripen NG were the engine EJ200 with vectoring thrust, but with the cancellation the last, it were adopted the F414.

                      I have been keeping these doubts for years, but it could be resumed in this question: if the engine F414 does wonders for the Gripen NG, why it has been awaiting for 21 years to implement this?
                      Sigh...
                      "EJ200 with vectoring " was not "plan A".
                      SAAB invited bids by Eurojet and General Eletric, GE won.
                      The reason why the Swedes didn't stuck an F414 in a Gripen before is simple, money, redesigning a fuselage to house a bigger engine is complex (F4K anybody?) and expensive, at least by Swedish MOD standards.
                      sigpic

                      Comment

                      • Spitfire9
                        Rank 5 Registered User
                        • Jul 2008
                        • 2832

                        The shock and horror at the limited range of the Gripen NG when tested by Switzerland does seem to be misplaced, given that Gripen E will carry about 40% more fuel than the NG tested. In a way the test demonstrated that Gripen C would have inadequate range but so what: SAAB was not offering Gripen C to Switzerland
                        Sum ergo cogito

                        Comment

                        • TooCool_12f
                          Rank 5 Registered User
                          • Dec 2009
                          • 3321

                          that sounds better

                          Comment

                          • hopsalot
                            Senior Member
                            • Aug 2012
                            • 3166

                            Originally posted by MSphere View Post
                            Yep, that's the one.. But now you need to account for fuel differences from Gripen D --> Gripen C and then from Gripen C --> Gripen E.
                            Yes, Gripen NG will have more fuel and range, but the Swiss were briefed on the proposed improvements and still rated the aircraft as deficient in range for their needs.

                            This is Switzerland we are talking about here.

                            Like all planes the Gripen was designed with a certain sort of usage in mind. For that purpose (operating over friendly territory in a scenario where the enemy is coming to you) its range will be sufficient. People here need to stop wasting their time trying to invent scenarios where Gripens spend their time supercruising long distances and somehow rival a vastly larger aircraft like the F-35 in range and/or carrying capacity.

                            Comment

                            • hopsalot
                              Senior Member
                              • Aug 2012
                              • 3166

                              Originally posted by Spitfire9 View Post
                              The shock and horror at the limited range of the Gripen NG when tested by Switzerland does seem to be misplaced, given that Gripen E will carry about 40% more fuel than the NG tested. In a way the test demonstrated that Gripen C would have inadequate range but so what: SAAB was not offering Gripen C to Switzerland
                              Yes, but the leaked report also scored the proposed Gripen NG and it was still considered inadequate.

                              See page 12 and on : http://kovy.free.fr/temp/rafale/pdf/12332.pdf

                              Comment

                              • Spitfire9
                                Rank 5 Registered User
                                • Jul 2008
                                • 2832

                                Originally posted by hopsalot View Post
                                Yes, but the leaked report also scored the proposed Gripen NG and it was still considered inadequate.

                                See page 12 and on : http://kovy.free.fr/temp/rafale/pdf/12332.pdf
                                Yes. The Swiss tested the aircraft they were given to test.

                                I note what the report says of Defensive Counter Air performance where Gripen was concerned (page 6):

                                The main weak points of Gripen were endurance and aircraft performances. These two weak points cannot be improved without a change in the structure of the aircraft. These weak points will probably never improve during the entire life of the Gripen C/D aircraft but rather be addressed within the concept of the new Gripen NG.
                                That's what the defence minister chose - an aircraft that had not yet been built so inevitably could not be tested. Why? I think for financial reasons and I think he was also aware of opposition to any new fighter being ordered by a proportion of the Swiss electorate and, if it came to a plebiscite, his best chance of getting more than 50% backing for a new fighter was with Gripen.
                                Sum ergo cogito

                                Comment

                                • Loke
                                  Rank 5 Registered User
                                  • Jun 2008
                                  • 3302

                                  Ministry speeded up the process variations of supersonic aviation, when finalized the legal and financial details of the lease flight hours Jas - Gripen.
                                  google translated from: http://domov.sme.sk/c/20090066/minis...#ixzz3zfwI9pcj

                                  What does this mean? are they in the process of finalizing the contract? Or have they finalized?

                                  Comment

                                  • MSphere
                                    Senior Member
                                    • Feb 2010
                                    • 8983

                                    Originally posted by hopsalot View Post
                                    Yes, Gripen NG will have more fuel and range, but the Swiss were briefed on the proposed improvements and still rated the aircraft as deficient in range for their needs.

                                    This is Switzerland we are talking about here.

                                    Like all planes the Gripen was designed with a certain sort of usage in mind. For that purpose (operating over friendly territory in a scenario where the enemy is coming to you) its range will be sufficient. People here need to stop wasting their time trying to invent scenarios where Gripens spend their time supercruising long distances and somehow rival a vastly larger aircraft like the F-35 in range and/or carrying capacity.
                                    Gripen will lack mostly in supersonic range because it's tiny and you can't hang wet bags on it if you want to go over M1.0.
                                    But we have learned that the F-35's range at M1.2 is 150 miles only.. for whatever reasons.. that ain't considerably better than Gripen NG, methinks.. despite the aircraft being twice as heavy and large..

                                    Comment

                                    • Loke
                                      Rank 5 Registered User
                                      • Jun 2008
                                      • 3302

                                      Originally posted by hopsalot View Post
                                      Yes, but the leaked report also scored the proposed Gripen NG and it was still considered inadequate.

                                      See page 12 and on : http://kovy.free.fr/temp/rafale/pdf/12332.pdf
                                      According to the Swiss Air Force, they accepted Gripen E as a technically adequate solution, and overall the preferred solution, most likely because the budget did not allow for a sufficient number of Rafale to be bought; however it did allow for a sufficient number of Gripen to be bought.

                                      Interesting that:

                                      * F-16 did not participate (were they not invited?)
                                      * Boeing withdrew the SH, claiming it was "too advanced" for the Swiss requirements, and recommended Switzerland to buy Gripen instead! (more likely they realized the SH could not fit into the small budget)

                                      After a thorough review of Switzerland’s requirements for partial replacement of its Tiger fighter aircraft, Boeing has decided not to enter the competition due to the disparity between the requirements for an F-5 replacement aircraft and the next-generation capabilities of the F/A-18E/F Block II Super Hornet,”
                                      https://www.flightglobal.com/news/ar...act-ra-223401/

                                      Comment

                                      • Spitfire9
                                        Rank 5 Registered User
                                        • Jul 2008
                                        • 2832

                                        Originally posted by Loke View Post
                                        Interesting that:

                                        * Boeing withdrew the SH, claiming it was "too advanced" for the Swiss requirements, and recommended Switzerland to buy Gripen instead! (more likely they realized the SH could not fit into the small budget)
                                        I thought there was a problem with fitting F/A-18 into existing shelters sized for F-18 and it would have cost a lot to enlarge the shelters.
                                        Sum ergo cogito

                                        Comment

                                        • Spyhawk
                                          Rank 42 Registered User
                                          • Dec 2011
                                          • 175

                                          Originally posted by Spitfire9 View Post
                                          I thought there was a problem with fitting F/A-18 into existing shelters sized for F-18 and it would have cost a lot to enlarge the shelters.
                                          This is not the only reason, as the shelters would have needed to be also enlarged if the Rafale or Eurofighter had been selected. Increase of cost was about 500'000 mio.

                                          Comment

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