Moderator: MOD_Command
ORIGINAL: DrRansom
First, good news on the reduced visibility after motor burn-out
I have a question about the missile modeling, do you model:
A. Proper intercept trajectories, e.g. Proportional Navigation or Ballistic Fly-out to increase range, a la S-400 / SM-6?
B. Decreased maneuverability at high altitudes and increased drag at low altitudes?
Yup, that was one of those - whoa, here's a pilot whose had experience across multiple U.S. air-frames and he's telling you all the beliefs you had as a pilot until now are wrong. And, that the newest pilots coming straight into F-22s were the most lethal because they weren't thinking like a 4th gen pilot.ORIGINAL: ExNusquam
To tack on to what ckinfinite said, if you watch the brief that cheechako posted, it mentions that the saying "speed is life" no longer applies. He goes on to say that the least impressive thing about the Raptor is it's maneuverability. "Super agility" what's probably added to the list of characteristics when the F-22 was the only 5th-gen fighter and we'd had limited operational experience with it. Now that we've we've figured out how to use the Raptor, and seen that the F-35 can bring those same advantages without the agility, the characteristics were revised.
My only concern here is the US especially is banking on these theories. We heard similar theories in the late 50's and early 60's. So guns were left off a number of fighters in the US and UK. And look what happened when combat inevitably happened...
2) Ability to rapidly change the flight *vector* (e.g. supersonic crank right after a BVR launch, to ruin the incoming enemy's DLZ, or a super-Split-S to trash the engagement geometry of an incoming SAM).
ORIGINAL: ckfinite
Hmm, I hadn't thought of this. What kind of aircraft features improves performance in doing these maneuvers? I understand how to improve the qualities of #1, but less so #2.
ORIGINAL: Cheechako
https://www.youtube.com/watch?v=zxK6O5--9Z0
Here's the perspective of a hornet, super hornet(as a Top Gun instructor), viper, F-22 and F-35 pilot. He also did a tour as a FAC in Iraq. It's probably one of the best interviews I've seen explaining what is 5th gen - and why it's a big deal.
Yeah, we consider that a MiG-29 and a F-15 are both 4th gen designs. Both designs are very very different. They followed different phisolophies, use different technologies. If we apply the same rigid criteria that we use in the 5th gen, the Soviet fighters should a 3.5, 3++... But nopes. MiG-29 and Su-27 are both 4th gen fighters.ORIGINAL: ckfinite
I am talking about the lockheed's classification which many people use today (they forgot the super-agility which was dropped by Lockheed when the F-35 enter in the field).
Super maneuverability is not a game-changing feature the way LO is. It's been present since the 3rd generation in various forms, and has been especially prevalent in Russian 4th generation designs. Why? Because the Russians don't have the ability to keep up with the West in terms of electronics or stealth coatings, as demonstrated with their eternal AESA trouble and PAK-FA maladies, and need to sell it for all they've got. It's only really useful in the low-speed endgame, when you have a single chance and then you're dead. Agility is not a deciding factor in determining which generation an aircraft fits into.
The idea behind the 5th generation moniker is that it denotes aircraft that incorporate the more modern network based sensor model, as well as stealth. This looks to be a very good distinction going forwards, too. Look at the difference between the Eurofighter, the Gripen, and the Rafale, and what's coming next. We have the ATD-X, the PAK-FA, the J-20 and J-31, K-X, and a lot besides. These aircraft are fundamentally different than the eurocanards because they have stealth functionality and systems designed around that stealth capability. VLO capability is a good distinction, because it draws a clear and easy to distinguish line between these generations. Lockheed may have made the term up, but these future aircraft projects are demonstrating that their criterion has a lot of merit as a distinguishing feature.
What we do know, however, is that VLO designs reduce detection radius, regardless of the radar equipment being used. In C:MANO, the F-22 is detected by the PAK-FA's wing radar at 31 nm, vs 119 nm for an F-15C. This represents a 90% reduction in search area for the wing radar. So VLO, even if less effective in certain bands, will still change things.So why? It's very curious, specially when maneuverability, top speed, range, BVR capacity... are intrinsic parameters of each fighter (only depends of the fighter). But VLO isn't an intrinsic parameter of each fighter. Maybe, ATM VLO is an illusion if the new S-400 can work in a bistatic mode for example. We know that PAK FA and Su-35S have two radars, one working in X-band an a wing radar working at L Band...So We cannot treat VLO in the same way that we treat other parameters. Now F-22 can have VLO, but tomorrow nobody knows.
Actually, we have a very good idea that the J-20 is a VLO design: http://www.ausairpower.net/APA-2011-03.htmlWe don't know if the new Chinese designs are VLO, we think that but only based in the angular shape of the fuselage. And also we think that the lack of an angular shaped fuselage in the Eurocanards means that they aren't stealth. Stealth isn't an absolute parameter (Either you have or you haven't).
The laws of physics are the same for all. Radar equipment is fundamental for RCS. Power emission, wavelength and polarization of the wave are parameters for RCS formula.ORIGINAL: ExNusquam
What we do know, however, is that VLO designs reduce detection radius, regardless of the radar equipment being used. In C:MANO, the F-22 is detected by the PAK-FA's wing radar at 31 nm, vs 119 nm for an F-15C. This represents a 90% reduction in search area for the wing radar. So VLO, even if less effective in certain bands, will still change things.So why? It's very curious, specially when maneuverability, top speed, range, BVR capacity... are intrinsic parameters of each fighter (only depends of the fighter). But VLO isn't an intrinsic parameter of each fighter. Maybe, ATM VLO is an illusion if the new S-400 can work in a bistatic mode for example. We know that PAK FA and Su-35S have two radars, one working in X-band an a wing radar working at L Band...So We cannot treat VLO in the same way that we treat other parameters. Now F-22 can have VLO, but tomorrow nobody knows.
Thanks for the link.ORIGINAL: ExNusquamActually, we have a very good idea that the J-20 is a VLO design: http://www.ausairpower.net/APA-2011-03.htmlWe don't know if the new Chinese designs are VLO, we think that but only based in the angular shape of the fuselage. And also we think that the lack of an angular shaped fuselage in the Eurocanards means that they aren't stealth. Stealth isn't an absolute parameter (Either you have or you haven't).
You are correct, stealth operates on a spectrum, so RCS reductions can have a tangible effect even if they don't approach "VLO" status. So while the many new 4.5 gen aircraft like Super Hornet include "stealth features", they won't yield the same reductions in search area/difficulty in detection as something that is designed from the ground up to include those features.
VHF radars offer better performance against stealth targets that are optimized for the FCR bands (S/X). However, better performance does not mean that they can detect stealth targets at the same ranges as non-stealth targets. Detection in these bands is the result of resonance off of certain aircraft features, and even if these features are not optimized for the VHF band, they will still offer some use. Recall that in the F-117 shootdown, the F-117 was detected at a range of 30-37 miles (by a VHF radar), much closer than if the the F-117 had been conventionally shaped. Because effective search area decreases with the square of detection range, this reduction represents a significant reduction in search area.ORIGINAL: Zaslon
The laws of physics are the same for all. Radar equipment is fundamental for RCS. Power emission, wavelength and polarization of the wave are parameters for RCS formula.
Here Carlo Kopp wrote about VHF radars
Passive radar and the future of the US military airpower by Westra.
I believe you are misreading the context of the conclusion. The article was written in response to initial responses that claimed that the J-20 prototype could never be a VLO design because of it's engines, or it's shaping, etc. So while Kopp is saying that the prototype is not VLO, the production variant can be build to that standard.Thanks for the link.
We haven't a very good idea. We can suppose. The Authors present the study as a 'preliminary assesment'. A preliminary assesment never can be seen as an evidence, fact or absolute statement. It's more than a hint, a clue.
Also in the conclusion, the authors wrote:
In conclusion, this study has established through Physical Optics simulation across nine frequency bands, that no fundamental obstacles exist in the shaping design of the J-20 prototype, which would preclude its development into a genuine Very Low Observable design.
They aren't saying that the J-20 is an VLO design.
If you assume the drafting boards are 1m^2, how far away could you detect them with a VHF radar?[:D]ORIGINAL: thewood1
I think the main problem is they drafting boards and T-squares to design parts of the J-20.
Exactly, they can detect stealth targets at the same ranges as non-stealth targets, it's a possibility, not an absolute statement. They can lost his advantage. Remember that there are some parameters in addition to the wavelength.ORIGINAL: ExNusquam
VHF radars offer better performance against stealth targets that are optimized for the FCR bands (S/X). However, better performance does not mean that they can detect stealth targets at the same ranges as non-stealth targets. Detection in these bands is the result of resonance off of certain aircraft features, and even if these features are not optimized for the VHF band, they will still offer some use. Recall that in the F-117 shootdown, the F-117 was detected at a range of 30-37 miles (by a VHF radar), much closer than if the the F-117 had been conventionally shaped. Because effective search area decreases with the square of detection range, this reduction represents a significant reduction in search area.ORIGINAL: Zaslon
The laws of physics are the same for all. Radar equipment is fundamental for RCS. Power emission, wavelength and polarization of the wave are parameters for RCS formula.
Here Carlo Kopp wrote about VHF radars
Passive radar and the future of the US military airpower by Westra.
So... we haven't a very good idea that the J-20 is a VLO design. It's a posibility. [;)]ORIGINAL: ExNusquamI believe you are misreading the context of the conclusion. The article was written in response to initial responses that claimed that the J-20 prototype could never be a VLO design because of it's engines, or it's shaping, etc. So while Kopp is saying that the prototype is not VLO, the production variant can be build to that standard.Thanks for the link.
We haven't a very good idea. We can suppose. The Authors present the study as a 'preliminary assesment'. A preliminary assesment never can be seen as an evidence, fact or absolute statement. It's more than a hint, a clue.
Also in the conclusion, the authors wrote:
In conclusion, this study has established through Physical Optics simulation across nine frequency bands, that no fundamental obstacles exist in the shaping design of the J-20 prototype, which would preclude its development into a genuine Very Low Observable design.
They aren't saying that the J-20 is an VLO design.
