XB-70I’m not sure what their contract requires. So that could set them back by few years. I don’t know how much. But even if they are constrained by contract to where they cannot use test materials and data, they still do have personnel with the required knowledge and experience who can think to do it another way. And they have a brand new core design in Advance3 that they can play with. They are in better shape than most.
XB-70@RALL – OK, I’ll accept that. But then the follow on is: and what did they gain from that? The F-22 and such shows you can do just fine with around 25%. I’m not aware of anything where the Typhoon really stands out.
XB-70Actually the weight percentage of composite materials used in the construction of the Eurofighter is around 50% (70% surface)
Source? Because that is really high…building the frame and ribbing with such a high portion of composites in the frame and ribbing adds a lot of cost for little benefit. Composites tend to have really good tensile strength, but it is difficult to give them good compressive strength (you have to be an ace with your resin for this). And, although tensile strength is the more important of the two, you do need both. The F-35 only has 35% by weight; the F-22 25%.
XB-7040-44% aluminium
22-26% composite
18% titanium
10% steel
4% othercomparison-EUROFIGHTER TYPHOON:
GENERAL MATERIALS
Carbon Fibre Composites
70%
Metals
15%
Glass Reinforced Plastics (GRP)
12%
Other Materials
3%
Um, you are making the mistake of comparing percentages by weight (Su-57) to percentages by surface area (Eurofighter). Those are two very different things! The construction of the Su-57 matches other modern fighters.
XB-70mrmalaya, you´ve just made me think, if a prototype is going to be “flyable” around 2025 its going to need engines, the alocated budget and timeframe precludes having a entirely new engine by that date, its probable that a pair of (modified?) EJ200´s will be the propulsion for the prototype.
Yeah, they almost certainly won’t develop an engine from the ground up. Like you say, the schedule does not permit it. But it might not be an evolution of the EJ200. It could end up being an adaptation of Advance3 instead – the new civilian core that they are developing to replace Trent on airliners. (They first ran Advance3 on the bench in November of last year) Rolls Royce has technology options. The UK is actually better prepared than the EU in that field.
That said, for a 2025 first flight I think they will have to do what the Russians and Chinese did and have the early prototypes running on a temporary engine. Or they could postpone the schedule (likely).
XB-70You mean the adaptive engine is already in development by Rolls-Royce? Has any demonstrator already been produced or is there any available info on it? Had only heard of ADVENT
@LMFS – They produced an adaptive fan for rig testing back before they were bumped off the ADVENT program.
https://www.rolls-royce.com/media/press-releases-archive/yr-2009/240609-advent-milestone.aspx
Since the fan is a crucial part of an adaptive cycle engine, and they’ve had plenty of time to experiment with it, they likely have a pretty good idea how to go about it. That said, they are still in the very early stages of development. They don’t have an assembled prototype. They’ve got to construct a whole engine around their technology, and then bench and flight test it. They still have a good decade of work ahead of them with regards to the engine.
XB-70I don’t think India will be interested in this project at this point of time …
I don’t think India will be interested simply because the timing works horribly for them! India isn’t sweating bullets over the J-20 yet. There aren’t that many of them yet and the design needs to mature a bit to gain all aspect VLO performance. Their materials technology in the hot section (engine and nozzle) needs to advance dramatically. But China is only going to keep improving it, and so come five years from now the Indians might have a real concern regarding the regional balance of power. So they are likely to start looking toward a near term solution within the next few years, and 2035 is unlikely to be soon enough.
XB-70“Marines Need Special Lightning Rods to Shield Their F-35s In Japan from Storms (excerpt)”
Unlike traditional paints, stealth coatings have been specifically optimized with regards to absorber particle size, particle density, conductivity, magnetic permeability, electrical conductivity, capacitance and such to maximize RF absorption across the desired frequency bands. A lightning strike momentarily puts tens of thousands of amps through it (briefly ionizing it) and absolutely trashes those carefully balanced characteristics. All operators will learn that such an event costs them a lot more than a singed paint job. The Chinese and Russians will learn that too.
XB-70…only the US reneged the deal. Its biggest (by far) trade partner is China who´ve just increased its oil inports from Iran.
We’ll see, Sintra. Yes, only the US reneged, but companies around the world will choose to comply nonetheless…so that they can continue using US financial markets. I’m sure the Chinese will buy more oil – since the price will drop due to the reduction of demand elsewhere. It’s really smart for them. But are the Iranians going to get any appreciable Euros or dollars out of it? Probably not, because the price of their oil will drop and insurance costs will rise (the big insurance companies being deeply intertwined with the US financial market). I think foreign currency will be extremely hard to come by in Iran. But we’ll see.
XB-70It looks like the fanboys (on both sides) were shown to be wrong. The program wasn’t cancelled and nor is it entering into any substantial production soon. I argued as much on page 8 of this thread. The success of the Su-57 is dependent on the Izdeliye 30 engines. The Su-57 was never designed to achieve all aspect VLO with the 117s and nor can it. The Russians are very experienced at taking turbofan designs through the testing phase. If there were anything wrong with the Izdeliye 30 they would almost certainly would have already discovered it and began working on a fix. Almost! There is always some risk, and with Russia’s current budgetary conditions they are simply going to avoid it by waiting. They will build just enough small batches to keep the workforce proficient, but they won’t ramp up production until the engine has passed its tests. The latest info suggests 2023.
Watch the engine flights. They are the best indicators of the health of the program.
XB-70Russia and China.
It’s not that simple. They would both expect to be paid. And, with sanctions in place, it is going to be hard for Iran to come by any foreign exchange currency – dollars, yen, euros, etc. And neither the yuan or the ruble are in significant use yet.
XB-70India’s 5th-Gen Fighter Jet Expected to Make Maiden Flight in 2032 – Reports
“The AMCA will feature geometric stealth…might later incorporate material stealth.”
Worthless source. There is no such thing as geometric stealth. All stealth designs combine geometry and materials – combining impedance matched absorbent coatings, microscopic surface patterns, transparency factors for interior re-entrant surfaces, deeply buried reflective surfaces, etc. The F-117 and B-2 still have the best shaped aerodynamic surfaces. But even they were heavily dependent on materials – that’s why they were hangar queens.
XB-70Very interesting find, panzerfeist1! I’ve played around with translating it and had the same problems as you. I tried to translate just the word and it gave me “Gbode” but a flag popped up that stated it was being translated from Bulgarian. I believe the actual word is “Gbaud” for gigabaud, which is an older terminology for data transfer rates and has generally given way to bit rate (Mbit, Gbit, etc.) Except in some very special cases, they are the same.
https://en.wikipedia.org/wiki/Baud
I don’t believe you can assume that it has a 24Gbit/s data bus though since fiber channels with throughputs of less than 1Gbit/s also exist! It likely is 8Gbit/s as stated elsewhere.
The stats on its data processor modules were also interesting. It’s got two of them based on a multicore technology – so four cores at the minimum. It’s going to be a beast at information processing & relaying in comparison to legacy designs.
XB-70Ummm, not so much HF radar (like Ka band he referred to).
OK, I agree that it won’t fall off quite as much or as fast for higher frequencies not too distant from the X-band. (So lower to mid Ka band). But, actually, at higher frequencies the RCS reduction measures can be defeated just as easily as with low frequencies. For a visual example:
https://www.wired.com/2010/12/lockheed-cross-breeding-raptors-joint-strike-fighters/
See those internal triangular sections outboard of the engine nozzles. The Raptor’s RCS reduction measures works best when that outer skin is least reflective and both most absorbent and transmissive. That way the largest amount of RF energy can be drawn into the re-entrant surfaces and attenuated away – and the outer skin absorbing any small specular reflection.
If you drive frequency way up to where that outer skin is no longer mostly transparent then the Raptor’s shaping and absorbent coatings are seriously compromised. This is why the Chinese, Russians, and such are pursuing ROFAR.
So the basic principle that stealth technology works better as frequencies increase is false.
XB-70Against stealth shaping, radars get worse the higher band you go
That is not true. There are many factors involved which will yield an optimal frequency. And the RCS reduction measures will diminish in effectiveness on both sides of that frequency.
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