RadDisconnectLots of rampant speculating on both sides…
haavarla, have you taken an aircraft structures course? Because the T-50 has no shortage of holes, and in fact is structurally riskier when it comes to bending moments. The main weapons bays occupy quite a bit of volume and effectively decreases it’s area moment of inertia (1/12*b*h^3 for a rectangle) in the longitudinal axis since h in the area between the engines is effectively reduced. There’s a reason we saw spanwise reinforcement plates on T-50-1, -2, and -4, and why the design is getting a structural overhaul starting with T-50-6-2. Sukhoi evidently chose this structural design and tackle the challenges to get more weapon bay volume. The T-50 wouldn’t necessarily be structurally simpler, it’s just a design trade that Sukhoi chose. Which brings me up with this statement.
On top of all these empty holes, we all know that a blended wing/body design is a far more efficient way of dealing with lift/drag/internal volume/weight on a fighter.
What do you define as “blended wing/body”? And what actual data do you have to back up these claims? Eyeballing the drag difference between an F-22 and T-50 would be incredibly unreliable; you need to account for surface area, fineness ratio, potential sources of interference drag (including shockwaves), aspect ratio, and a bunch of other factors. Your use of terms like “sleeker” or “more aerodynamic” is meaningless. It’s very poor engineering practice to make such generalizations without having access to actual test data, or what design trade studies were done during the design process. Otherwise, why would the Chinese chose a different layout for their J-20? Why did the Japanese choose closely placed engines in their ATD-X? Why does the prospective EMD F-23 position the engines closer together compared to the YF-23?
I actually really like the T-50, but I find your analysis of its merits to be incredibly flawed and seem to come from someone without aerospace engineering background (I’m currently earning my degree in this area).
hopsalot, no one is claiming that the T-50 is some magical aircraft that has no compromises, and no one here is backing up the performance figures on that chart (which I guess is what you have issue with). But it’s silly to assume that the T-50 somehow can’t improve on certain aspects of the F-22’s design (while making certain tradeoffs in other parameters). It’s perfectly reasonable to say that the T-50 is structurally lighter than the F-22, and the difference isn’t drastic anyways (18,000 kg vs 19,700 kg). Given that it carries more internal fuel than the Su-27 (this was stated by Sukhoi test pilot Sergei Bogdan) there’s no reason why it can’t have 3,500 km subsonic range, which is comparable to the Su-27’s 3,530 km range.
Also, the difference between the F-22/F-35 and T-50 inlets aren’t a simple “fixed or variable geometry” comparison, so I’d be cautious about comparing their pressure recoveries. They use different methods of maintaining the normal shock at the throat, and they all generate multiple oblique shocks. The precise nature of how they work is classified.
RadDisconnecthopsalot, you do realize that the T-50 design is some 14 years newer than the F-22’s. There certainly is room for some improvement in those years. But that said, figures on that chart do seem inflated and I don’t think anyone but fanboys are claiming that the T-50’s performance is vastly superior across the board. Based on current information, speed appears to be comparable. Maneuver performance would seem to somewhat favor of the T-50 in pitch and especially in yaw, but given the inertia of the widely spaced engines, rolling acceleration (very important but frequently overlooked) probably isn’t as good as the F-22, which in turn is not as good as the F-16. The T-50’s advantage in range is not a surprise, given its much higher fuel load compared to the F-22. Also, all-aspect RCS performance of the T-50 probably won’t match the F-22 due to shaping in the aft sector. This might be a consequence of aerodynamics being a greater design driver compared to RCS.
I think we need to stop speculating on the differences between F-22 and T-50 inlets, it’s becoming tedious and unproductive, since the difference between the two aren’t a simple “fixed vs variable geometry”. I’d like to point out that while the T-50 is probably more aerodynamically advanced than the F-22, relying on eyeball analysis to definitively state the aerodynamic differences are rather premature, which is why I didn’t state them in absolutes.
Also, trying to determine which aircraft is overall superior is not very meaningful, since the F-22 and T-50 are designed with different missions and threat environments in mind.
RadDisconnectI think we are making too many presumptions with aircraft structures. There are no shortage of “holes” in the PAK FA structure, and given the small size of the SRAAM bulges, it would seem like those bays are semi-recessed. Also, the placement of the main weapon bays on the PAK FA is structurally quite risky and challenging especially due to bending moments, but Russian engineers chose to tackle that in order to get substantially more payload out of the T-50 compared to the F-22. In any case, the structural design of the PAK FA is still a work in progress, though I believe that they will meet their goal. Though the T-50 may be lighter, it isn’t drastic, roughly 18,000 kg empty weight vs 19,700 kg for the F-22.
Also, based on what djcross has said, it seems like the F-22’s inlets are much better than F-16’s, and as good if not better than F-15’s. Apparently these inlets are designed so that much of the performance limiting spillage drag on the F-16 and F/A-18 are avoided. That said, the T-50’s inlets are also very sophisticated, so comparisons are difficult, but either way, materials, instead of inlets, appear to be the limiting speed factor for both F-22 and T-50. Regardless, I think hopsalot’s point is that the figures on that paralay chart seems inflated, and I agree, even though no one doubts that the T-50 is a kinematic monster.
RadDisconnectwho claimed MIG-25 world greatest? if it was world greatest Flanker/Fulcrum would not have been started early 70s. Su-35 is not built by soviet system those people either went to west or left over in republics. My predictions is Su-35 will outperform its publish specifications.
:rolleyes:
By the way, I believe Sergei Bogdan said that the T-50 has more fuel than the Su-27, not the Su-35S. And Mihkail Pogosyan said range was about 3,500 km subsonic.
Also, despite being fixed geometry, the F-22 inlet generates multiple oblique shocks and has a compression ramp and bleed system that maintains a normal shock at the inlet throat. It’s materials, rather than inlet performance, that operationally limit the F-22 to Mach 2.
RadDisconnectThe performance figures seem way too good to be true. Mach 2.1 supercruise? Wasn’t max speed was reduced from Mach 2.35, to Mach 2.15, to Mach 2 due to materials? Also, I believe Mikhail Pogosyan disclosed the subsonic range to be 3500 km. Also, 2016 is nowhere near IOC, since that’s when the first production aircraft gets delivered to RuAF. As I’ve mentioned, by the time the F-22 hit IOC, about 60 aircraft had been delivered, and FOC was achieved when over 90 were in service.
I really like the PAK FA, but it seems like the figures here are somewhat inflated and optimistic.
RadDisconnectSpeaking of inlets, schematics of the EMD F-23 shows that it would have a fixed inlet with what looks like a bump, similar to that of the F-35.
RadDisconnectAs I understand, the F-22 and F-35 inlets are variable in the sense that they control the pressure to maintain the normal shock at the inlet throat. The T-50 uses variable inlet ramps, and concealment of the compressor face is done with a radar blocker. That said, given that both the F-22 and T-50 are operationally limited to Mach 2 due to materials, it seems odd that Sukhoi chose to use a variable ramp inlet, despite the additional complexity and maintenance.
RadDisconnectSupersonic airplanes use at least one oblique shock and one normal shock and a divergent inlet duct to recover pressure before the airflow enters the fan.
Legacy jet technology used moving inlet ramps or spikes to control the position of the final normal shock and may provide the benefit of reducing spillage drag by altering capture area.For the F-22 and F-35, oblique shocks are created by the forward most corner of the inlet lip and the normal shock is captured just behind the oblique shocks. Excess airflow is dumped overboard by pressure relief valves on the dorsal side of F-22 via sawtooth louvers, or into the F-35’s engine bay through a series of slots where it ventilates the bay and exits through the sawtooth gap between the aft fuselage and engine nozzle.
What would be the disadvantage of the F-22 and F-35 inlet compared to one with variable ramps? Sukhoi chose to use an inlet with variable ramp (and a radar blocker) for the PAK FA, despite the additional maintenance and complexity.
RadDisconnectDeino, do we have an estimate of the dimensions of the PL-10? I suppose there are people who have already compared its length with the J-20 to provide estimates.
RadDisconnectDo we have any idea when the T-50 will achieve “Western” IOC? For comparison, the F-22 reached IOC in December 2005, and by that time there was already a training squadron at Tyndall, and a combat squadron (27th FS) at Langley, which makes for about 60 aircraft. When can we expect the T-50 to reach a similar status? I understand that the original plan was 55 T-50’s by 2020, but recent articles seem to indicate that this has been pushed back.
RadDisconnecthttp://breakingdefense.com/2015/03/threat-data-biggest-worry-for-f-35as-ioc-but-it-will-be-on-time/
There’s been some talks of the F-35 being stealthier than the F-22, and in the X-band that’s certainly possible given the more modern RAM used on the F-35. Also, I think “stealthier” can also be attributed to the F-35’s coatings being easier to maintain than the F-22’s. So while the F-35 probably won’t match the F-22’s stealth in bandwidth, it can very well be stealthier in higher frequencies.
Makes me wonder if there will be a deeper overhaul of the F-22 later in its life cycle when it can get this Fibermat material and other good stuff that the F-35 has (updated sensors, etc).
RadDisconnectI admire the photo-blowing-up skills and the diligent accounting, not to mention the blithe assumption that nobody would manipulate public, unclass mockups and images, but how do all those extra modules track the photons that go screaming past the edges of a smaller aperture?
I can have the most awesomely designed and engineered camera lens in the world, but if it’s an F:2.8 it’s still not going to do the job of an F:2 in low light.
Wasn’t it you who was telling people what the F-35’s static margin is by eyeballing the free stream of the downwash?
RadDisconnectI don’t see the point of attempting to restore -55 other than publicity and saving face. The damage seem to be rather extensive, and for the effort and cost they might as well salvage usable items from the wreck and get it over with. Oh well, it’s probably the same reason LM and USAF are not declaring F-35A AF-27 written off: pure publicity.
I do look forward to the second stage T-50 with non-metallic nacelles. Any estimated date on that?
RadDisconnectWhat exactly is this about? Su-35S is somehow fifth generation? :confused:
“We have been negotiating and have signed the intention protocol for the Su-35,” Rostec CEO Sergey Chemezov said during the IDEX show in Abu Dhabi last month. “Now we are working on designing ideas for this contract and on creating a manufacturing platform for the aircraft of the fifth generation.”
Rostec is Russia’s state-run corporation that oversees export of high-tech products.
Chemezov said the jet would be developed to meet the Indian Air Force’s requirements. He did not say how many of the jets India might plan to buy.
RadDisconnectFrom what I’ve read in sources so far, there are two launchers for the T-50’s main bays. The UVKU-50L for missiles weighing up to 300 kg (660 lb), and the UVKU-50U universal launcher for weapons weighing up to 700 kg (1540 lb).
For simplicity, if we assume that the T-50 carries two UVKU-50U per bay and each are loaded to it’s weight capacity, that’s 2800 kg (6160 lb) of internal weapons without counting the SRAAM missiles.
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