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Su-57 News and Discussion -version_we_lost_count!-

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  • Jō Asakura
    多聞天
    • Jan 2011
    • 1297

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    • Jō Asakura
      多聞天
      • Jan 2011
      • 1297

      Click image for larger version

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      • TomcatViP
        Rank 5 Registered User
        • Nov 2011
        • 5856

        Originally posted by Austin View Post
        [b] unstable in the lateral
        I am sorry but the airframe is symmetrical regarding a vertical plan encompassing its main axis meaning that it is at least neutral in 'lateral' (yaw) and roll. It can be divergent of course but not "unstable".

        Notice that I have long ago supposed that the -Fa* was made able to fly sideway efficiently (frontal stealth).

        Last edited by TomcatViP; 14th March 2019, 20:49.

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        • LMFS
          Rank 4 Registered User
          • Feb 2018
          • 246

          Originally posted by TomcatViP View Post

          I am sorry but the airframe is symmetrical regarding a vertical plan encompassing its main axis meaning that it is at least neutral in 'lateral' (yaw) and roll. It can be divergent of course but not "unstable".

          Notice that I have long ago supposed that the -Fa* was made able to fly sideway efficiently (frontal stealth).
          AFAIK the term "unstable" referred to planes means that, instead of having a tendency to return by themselves to horizontal levelled flight, they will keep or even amplify a given deviation command. For instance a F-16 can keep a "nose up" attitude even when the elevators are levelled whereas a "stable" plane would not.

          In terms of lateral instability I am also not sure if they refer to yaw, roll or both. In any case, stability to roll moment depends normally on the wings dihedral and position of CoG among others, given its layout it may well be that Su-57 has very little roll stability. Don't know much about yaw stability

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          BTW what do you mean with your last sentence?

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          • TomcatViP
            Rank 5 Registered User
            • Nov 2011
            • 5856

            Good point with the diedral. I have in mind positively stable or not, what would mean in the way I phrased it above, stable, neutral or "divergent".

            Regarding the "sideway" term, I have in mind a drifted trajejory where the plane nose is angled to its velocity vector (similar to the flat turn but with no curved flight path).

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            • Austin
              Rank 5 Registered User
              • Oct 2003
              • 6402

              https://tvzvezda.ru/news/opk/content...31419-5mml.htm

              Surpasses all analogues: the developer revealed the features of the engine Su-57

              the General Designer-Director OKB im. A.M. Cradles "Yevgeny Marchukov.

              I would say that this generation 5+ is slightly ahead of the fifth one. It is to this generation that the engine corresponds to specific gravity, specific consumption and specific gravity, Marchukov said. Marchukov noted that the engine surpasses all foreign analogues in terms of specific gravity, is a completely new product and has nothing to do with the engine of the Su-35 fighter.
              "A map does you no good if you don't know where you are"

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              • RadDisconnect
                Rank 5 Registered User
                • Jul 2013
                • 473

                Instead of brags, whats some actual numbers? 117S is 1,604 kg with 14.5 tons of thrust so t/w is 9. So if izd.30 is about 25% better, then t/w of 11.3, so similar to F-135 then?

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                • Austin
                  Rank 5 Registered User
                  • Oct 2003
                  • 6402

                  Interview with United Engine Corporation Chief on New features of 117 Engine currently on PAK-FA compared to 117S Engine on Su-35 and AL-31F on Su-30

                  http://vpk-news.ru/articles/8228

                  1 ) there will be new ceramic materials can withstand very high temperatures.
                  2 ) High-pressure turbine can operate without cooling blades, bearings - no lubrication.
                  3 ) Inlet temperature exceeds the temperature of the combustion theater kerosene at 2300 degrees.
                  4 ) The engine is a new low-pressure compressor.
                  5 ) Substantially upgraded high-pressure compressor.
                  6 ) The new combustion chamber.
                  7 ) The new turbine.
                  8 ) Almost all new units 80 % new parts compared to 117S
                  9 ) Weight Reduction of 150 kg link
                  10 ) Fundamentally new system of automatic control system (ACS) - fully digital, with full responsibility. For the first time it will be built at the Russian element basis. Architecture of the system, the control algorithm and its Russian counterparts
                  DATELINE: MOSCOW March 2

                  Russias fifth-generation stealth fighter jet will have a custom made new engine, Sukhoi General Director Mikhail Pogosyan said.

                  Claims that the fifth-generation jet allegedly has an old engine are wrong. Such claims are made by people with limited knowledge, he said.

                  The Saturn Research and Production center made digitally-controlled engines of Project 117 for the new jet. The engine thrust was enlarged by 2.5 tonnes, as compared with the AL-31 engines, while the engine weight was cut by 150 kilograms. That allowed the new jet to move at a supersonic cruise speed, Pogosyan said.

                  This engine meets the clients requirements. This is not an intermediate product made particularly for test flights. The engine will be installed in jets, which will be supplied to the Russian Air Force and prospective foreign clients, he said.

                  There will be another engine in the future, but it will take ten to twelve years to develop, Pogosyan said.

                  The fifth-generation fighter jet, also known as PAK FA, is being developed by the state-owned Sukhoi aviation company. According to information released by Sukhoi, the jet will be able to travel at 1,250 miles per hour and a range of up to 3,500 miles. It will incorporate stealth technology and come with air-to-air, air-to-surface, and air- to-ship missiles.

                  The jets first few test flights have already been carried out.

                  Source: Interfax-AVN
                  Last edited by Austin; 15th March 2019, 08:43.
                  "A map does you no good if you don't know where you are"

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                  • St. John
                    Rank 4 Registered User
                    • Jan 2018
                    • 545

                    What is that?

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                    • stealthflanker
                      Rank 5 Registered User
                      • Sep 2015
                      • 918

                      He's talking about the 117. Not izdeliye 30 unfortunately.

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                      • FBW
                        FBW
                        Rank 5 Registered User
                        • Dec 2011
                        • 3124

                        That article was from 2011. In light of what we know eight years later, the service was not satisfied with the -117 for production variants. It was (is) very much an interim engine until the izdeliye 30 is complete. Not sure why Austin reposted that.

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                        • panzerfeist1
                          Rank 4 Registered User
                          • Feb 2018
                          • 204

                          RadDisconnect "
                          then t/w of 11.3, so similar to F-135 then"

                          Why are we comparing the t/w of this engine to the F-135? I am sure that VTOL needs a lot of thrust to take of vertically than an aircraft that has to use a runway. If that t/w was correct wouldn't the F-35 easily outrun the SR-71 and even the claims of mach 4 with the mig-41? What measurements did you take to get t/w of 11.3? Wikipedia is telling me this for the F-35 regarding t/w.
                          • With full fuel: 0.87
                          • With 50% fuel: 1.07
                          and for the SU-57 its telling me this.
                          • AL-41F1: 1.02 (1.19 at typical mission weight)
                          • izdeliye 30: 1.16 (1.36 at typical mission weight)


                          Did I miss anything?

                          "Both the emitter and the receiver have been built on the basis of the experimental prototype as part of the R&D work. All this works and performs the location - we emit an ultra-high frequency signal, it is reflected back and we receive and process it and get the radar picture of an object. We see what we need to do to make it optimal," he said.

                          Lets say there is a target 100kms away. Can someone tell me the accuracy of how far off target would VHF, UHF, L-band or S-band would be in comparison to X-band guidance? I am experimenting with stealthflankers radar calculator using the 64 t/r modules of the k-77m with estimated power for each module in determining the width of the radar beam of what targets it can engage at certain distances for my own curiosity. Any feedback on this would be much appreciated.
                          Last edited by panzerfeist1; 15th March 2019, 15:37.

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                          • LMFS
                            Rank 4 Registered User
                            • Feb 2018
                            • 246

                            Originally posted by panzerfeist1
                            Why are we comparing the t/w of this engine to the F-135? I am sure that VTOL needs a lot of thrust to take of vertically than an aircraft that has to use a runway.
                            There is a F135-PW-100 which is the engine for the CTOL version of the F-35 and is widely supposed to be the best fighter engine available and thus the reference right now. It is said to produce 128.1 kN thrust dry, 191.3 kN wet (28,000 and 43,000 lb respectively).

                            The engine for the STOVL version is the PW-600. When configured for short take off or hovering, the thrust augmentation derived from A/B is not used but instead the BPR is notably increased through the additional lift fan. Thrust from the nozzle is notably reduced due to the big amount of power extracted at the turbine to move the fan and high pressure air bled from the compressor to feed the roll posts. Engine does NOT operate with A/B with the nozzle bent downwards. Total thrust is 175.3 kN, including nozzle, lifting fan and roll posts.

                            So conventional take-off configuration gives more thrust that hover or short take-off configuration, STOVL has nothing to do with any claimed extra thrust.

                            If that t/w was correct wouldn't the F-35 easily outrun the SR-71 and even the claims of mach 4 with the mig-41?
                            No, drag at supersonic speeds in F-35 is very high. Also max temperature the engine can operate under and configuration of the intakes (no variable ramps) limit fundamentally the speed of the plane. F-35 is not an aircraft designed to be a supercruiser or a highly supersonic interceptor, its engine has high BPR and is hence optimized for subsonic flight.

                            What measurements did you take to get t/w of 11.3? Wikipedia is telling me this for the F-35 regarding t/w.
                            • With full fuel: 0.87
                            • With 50% fuel: 1.07
                            and for the SU-57 its telling me this.
                            • AL-41F1: 1.02 (1.19 at typical mission weight)
                            • izdeliye 30: 1.16 (1.36 at typical mission weight)


                            Did I miss anything?
                            Data in Wikipedia are not to be taken seriously, they are unreliable and much less if you use TWR of the whole plane as starting point of your calculation. For instance, no official MTOW of the Su-57 is available and for the F-35 only information is 60,000 or 70,000 lb class. No official info about Izd. 30 thrust available either. The thrust I indicate above for F135 is credible though. Best weight estimates (USAF) indicate 3750 lb for the engine, that would mean TWR = 11.46. AL-41F1 is around 10 with the available information.

                            The article linked by Austin really means specific thrust is better than analogues. That is, more thrust per flow mass.
                            Last edited by LMFS; 15th March 2019, 21:02.

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                            • LMFS
                              Rank 4 Registered User
                              • Feb 2018
                              • 246

                              Originally posted by RadDisconnect View Post
                              Instead of brags, whats some actual numbers? 117S is 1,604 kg with 14.5 tons of thrust so t/w is 9. So if izd.30 is about 25% better, then t/w of 11.3, so similar to F-135 then?
                              No, they are not obligued to give away any numbers. Besides, they are not referring TWR but specific thrust. As said, TWR of AL-41F1 is around 10. That value is IMHO not going to be 25% better in Izd. 30 by increasing thrust a 25% since the engine's diameter remains largely the same, it would need to be rather through a very serious reduction in weight that you could reach a 25%improvement, and that is not a given. They said Izd. 30's TWR would be above 10 and that's all the information we have.

                              Comment

                              • GromOzekA
                                Rank 3 Registered User
                                • May 2018
                                • 13

                                Originally posted by panzerfeist1 View Post
                                Did I miss anything?
                                Yes, he is comparing T/W of the engines not the jets.

                                Also, i think information that F135 weight 1700 kg is not accurate. It's 65cm longer (about 13%) and 16cm wider in diameter (about 17%) than AL-41F1S, so it's about 30% bigger but only 6% heavier? Quite doubtful.

                                Comment

                                • FBW
                                  FBW
                                  Rank 5 Registered User
                                  • Dec 2011
                                  • 3124

                                  Originally posted by GromOzekA View Post
                                  Yes, he is comparing T/W of the engines not the jets.

                                  Also, i think information that F135 weight 1700 kg is not accurate. It's 65cm longer (about 13%) and 16cm wider in diameter (about 17%) than AL-41F1S, so it's about 30% bigger but only 6% heavier? Quite doubtful.
                                  Interesting theory, maybe you should contact the maintainers who work on the engine because the weight was listed twice in articles referring to them. I posted one. The other was scrubbed of weight data, after the fact. The OEM has never released the weight of the F119 or the F135, nor has the gov.

                                  Sources like Wikipedia extrapolated the weight based on engine thrust to weight of other contemporary engines.... they were wrong. We run into this type of denial all the time, opinion vs. data. Data says your wrong.
                                  Last edited by FBW; 15th March 2019, 23:46.

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                                  • FBW
                                    FBW
                                    Rank 5 Registered User
                                    • Dec 2011
                                    • 3124

                                    panzerfeist1 - are you so sure on the thrust to weight ratio of the Su-57? Has the official empty weigh ever been confirmed or are you using Wikipedia to extrapolate the thrust to weight ratio of the aircraft? Im guessing the later.

                                    Comment

                                    • panzerfeist1
                                      Rank 4 Registered User
                                      • Feb 2018
                                      • 204

                                      FBW "
                                      are you so sure on the thrust to weight ratio of the Su-57"

                                      I did not take this source serious anyways. He just did not specify the t/w and engine until LMFS cleared it up for me.

                                      Comment

                                      • Austin
                                        Rank 5 Registered User
                                        • Oct 2003
                                        • 6402

                                        Originally posted by LMFS View Post
                                        AL-41F1 is around 10 with the available information.
                                        117 Engine is 150 kg lighter than AL-31 and Thrust of 15 T , Dry weight of AL-31 is 1520 ( http://roe.ru/eng/catalog/aerospace-...ngines/al-31f/ ) , So 117/AL-41F1 weighs 1370 trust at 15T gives T:W Ratio of 10.9 or ~ 11: 1



                                        "A map does you no good if you don't know where you are"

                                        Comment

                                        • stealthflanker
                                          Rank 5 Registered User
                                          • Sep 2015
                                          • 918

                                          I'll be honest tho that it's kinda hard to believe. Maybe Pogosyan speak on 2 different engines. One being AL-31F in terms of thrust as for weight it's for other engine (perhaps the 117S).

                                          Being larger in diameter plus have a TVC. I doubt new material can make it any lighter than AL-31F. Even the figure of 1454 Kg (comparing it to 117S) Is already impressive.

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