It's imo an interesting academic debate that might be better had in a forum with less politically loaded sentiments.
J-20 5th Generation Fighter VII
- Thread starter siegecrossbow
- Start date
- Status
Zero-lift drag is not determined solely by absolute area and volume. An aircraft with larger volume and surface area can have a lower drag.
In another comparison with the Camel, a very large but streamlined aircraft such as the has a considerably smaller zero-lift drag coefficient (0.0211 vs. 0.0378) in spite of having a much larger drag area (34.82 ft2 vs. 8.73 ft2).
My understanding is that RadDisconnect was referring to distributional cross section comparisons. That said, I'm reasonably comfortable with concluding the J-20 has a more stretched cross section distribution than the F-22 given that it's not just longer but has a shorter wingspan and smaller control surfaces that aren't all placed aft of the wings.
Yes that's what I mean, supersonic drag at each Mach number depends on cross section area distribution, including maximum cross section area, where that maximum area is lengthwise, and the "smoothness" of the distribution and how good it follows the ideal curve, which changes with Mach number because the Mach plane angle changes. Not easy to eyeball and sometimes can lead to counterintuitive results. For example the longer YF-22 with higher sweep wings actually have higher drag than F-22 and supercruised slower even with the VCE YF120. Which is why it's not certain if J-20 maximum speed and drag is better than F-22. It may or may not, can't tell just by looking at it.
Just to throw my 2 cents into the discussion: From a materials point of view M 2.8 also doesn't seem quite like an "Operational" mach number, or at least something that J-20s in service would fly at normally, since starting at around M2.5 (I think) there is enough heat generated that certain areas of the skin will get severely damaged over time. Hense usually aircrafts aimed at higher mach numbers -have specialized skin material, be it steel (ala mig-25 and xb-70) or titanium (sr-71).
In this regard M2.8 is a bit neither here nor there: if regular composite and aluminum skin is used M2.8 is probably too fast for it to handle for anything other than test-flights in certain scenerios; and if the designers went the extra mile and used specialized materials then why not aim for a higher design Mach number?
(I know a million other reasons may lead to the design choices for max mach numbers, the "neither here nor there" comment was based strictly on a materials standpoint)
In this regard M2.8 is a bit neither here nor there: if regular composite and aluminum skin is used M2.8 is probably too fast for it to handle for anything other than test-flights in certain scenerios; and if the designers went the extra mile and used specialized materials then why not aim for a higher design Mach number?
(I know a million other reasons may lead to the design choices for max mach numbers, the "neither here nor there" comment was based strictly on a materials standpoint)
The whole discussion is ludicrous. The J-20’s airframe is not designed to operate at Mach speeds as high as 2.8. To be fair the 2.0 speed is lowballing and I suspect it to be practical operational speed, but 0.8 is too big a margin of error.
Ironically once you're past Mach 2.2 the drag curve drops low enough that you can just as easily keep accelerating to Mach 2.5 or even 2.8 if the air and flight conditions are right. This is how we get stories of the F-15 flying at Mach 2.8 on occasion, but these are extremely provisional incidents. Just sharing this point for the sake of fun apocrypha though. These sorts of situational occurrences don't have any real operational value.
At these speed, you are visible on IR like a shooting star...durable skin or not.
Have heard old story about canadian F-104 from a retired Airforce pilot. They where limited in speed for safety purpose because approaching mach 2, they had a tendency to speed off because the Canadian variant inlets where bending and letting way more air in, making a blazing acceleration ultimately destroying the engine. Canada's accident rate with the F-104 ultimately exceeded 46% over its 25-year service history
Inlets on the Italian ones where way stiffier and they were a bit jealous of them, making them able to go faster without blowing up.
Allegedly (!!!) the 131st Air Brigade is converting from J-10C to J-20, but it is not the main development here.
The photo is not a real image but sketches by the poster, claiming that CB09220 has appeared.
I have serious doubt whether it is true but many credible sources are re-posting it and add more details on this development like the change of radome.
My doubt:
1. The previous confirmed CB serial number indicated 20 aircraft per batch, so the 220th J-20 should be CB11220 instead of CB09220. However it is possible that each batch extends to 40 from some point of last year.
2. OP is in Chengdu instead of where 131st AB is based.
The photo is not a real image but sketches by the poster, claiming that CB09220 has appeared.
I have serious doubt whether it is true but many credible sources are re-posting it and add more details on this development like the change of radome.
My doubt:
1. The previous confirmed CB serial number indicated 20 aircraft per batch, so the 220th J-20 should be CB11220 instead of CB09220. However it is possible that each batch extends to 40 from some point of last year.
2. OP is in Chengdu instead of where 131st AB is based.
- Status