crobatoNot really. And its not resolved with excess thrust. And relaxed stability (lack of equilibrium) can be added into an aicraft by removing its stabilizing elements.
Words from an F-18 piloto.
http://www.seqair.com/FlightTest/Stability/Stability.html
“First, a very brief review of stability and control: The stability of any airplane is its tendency to return to equilibrium when displaced. Controllability is a measure of the ease with which the pilot can displace it from equilibrium. An extremely stable airplane might be very hard to control depending on the level of controllability. An unstable airplane may be impossible to control regardless of controllability. The F/A-18 I used to fly was designed with very relaxed static longitudinal stability-almost neutral. The relaxed stability and very strong controllability make it a highly maneuverable fighter-the airplane would be extremely difficult to control without the digital flight control computers. Static longitudinal stability is normally indicated in terms of stick force versus airspeed measured about a trimmed point of equilibrium. A simple graph explains:”
You can take a design that was stable and turn it unstable.
Words from another piloto.
http://www.thirteen.org/warplane/interview.html
“When the F-15 RFP [Request for Proposal] came out, General Dynamics proposed a high technology version of the F-15. This version included a fly-by-wire flight control system, relaxed static stability, side stick, slope back seat and a single piece windshield/canopy.”
crobatoThats pretty much all I have been able to find. I am just amazed that the Pero was not used either by the Chinese or by the RuAF Su-27SM upgrade. I have read that the Zhuk-MS is the ‘better’ radar, but if you already have the N001 this must be the easier option, if this realy was offered to China I cannot see why they would not backfit their entire fellt with it?
It seems more like the cheap Flanker market has dissapeared rather than it having been conquered, in hindsight it is not realy that surprising- anyone wanting a cheap fighter can have a Fulcrum. If you think you face a threat that requires a Flanker you probably want every goodie you can get.
I have mentioned this on another thread. That is, the N001VEP is not capable of surface MTI or Moving Target Indication. This is a special ground search mode where a moving target becomes discriminated against the background ground clutter by comparing doppler return signals of the moved object to the static background in relation to the moving aircraft. Once a potential moving target is detected, the target can then be identified friend or foe through SAR, FLIR or straight visual.
To do MTI you would need a monopulse antenna, with three or four emitting dipoles and the planar array set into 3 or 4 sectors of respective receivers. Slotted planar array easily fits this description, such as the Zhuk MSE, but the N001VEP uses a twist cassegrain antenna where angular resolution is resolved by conical scan. Unlike monopulse, which emits four differently located signals to be received at four different parts of the antenna, conical scan turns around the emitter horn located offset and near the circumference of the array, then reads and compares the recieved results as the disk is turned around.
Even though Pero is shaped like a flat planar array, to be compatible with the N001VEP, the phase array is simply emulating a twist cassegrain from the view of the back end, even though it can scan much faster than the true mechanical unit. The back end is simply not designed to work like a monopulse, and in order to do that, the circuit changes would have meant you are better off with an all new radar system.
In that sense, the PLAAF’s original pursuit of the Zhuk MSE was more logical.
crobatoDetecting ground targets is even more difficult due to the clutter issue. There is a reason why JSTAR unit cost is very high. If PLAAF’s AEW has only started to take-off, and its JSTAR-like project is also relatively new, it is clear the capability does not exceed JSTAR. Citing the fact that there are three AEW projects says nothing. PLAAF also has three on-going fighter projects, yet no one would say PLAAF aircrafts must be superior to F-22 / F-35, and things are “easy” for PLAAF fighters.
There is something called GMTI or simply MTI for short. Its called Moving Target Indicator. The doppler radar return of a moving target on the ground can be compared to the doppler radar returns of the stationary environment, allowing the moving object to be detected and discriminated. Its not really rocket science, GMTI started appearing in fighter radars in the West towards the mid to late eighties, for example with the FIAR Grifo radar on the F-104S Starfighter. What JSTARS did was to take the entire concept to a whole new level and added high resolution SAR mapping ability, though SAR can be added into the fighter radar.
I came upon that the KLJ-1 of the J-8II had GMTI, when someone pasted its specs, and the focus of his attention was the range of the radar and A2A engagement. He didn’t know what all the other abbreviations meant and just copied and pasted them, though they were clearly meaningful to people who had studied these before. One of the modes was MTI/GMTI. And this was the first generation slotted planar array that became operational with the PLAAF, which can mean the mode would have been refined and improved on later radars not only in newer fighter aircraft, but also in Y-8 and Y-7 surveillance aircraft. The most important plane to note is the Y-8 battlefield surveillance plane that has two massive phase arrays set on the side of the plane’s cheeks.
The reason why the Russians and the Chinese never had this before was become they came upon multisectored monopulse planar arrays designs rather late. To do this well, you need an array with at least three or four emitting horns, and the array divided into into three or four matching receiving sections. This in summary is a monopulse design. The results from four sections are compared to produce angular resolution information. Slotted arrays are designed this way. However, the Su-27s and Su-30MKK using twist cassegrain antenna and conical scan technique for determining angular resolution, do not lend to the implementation of MTI. Hence a factor why the PLAAF obsoleted them, stopped Su-30MKK/MK2 purchases and did not accept Su-27SM upgrade proposal from the Russians. JH-7A, J-10, J-11B, J-8F (later versions have a newer radar Type 1492), all have four sectored monopulse planar arrays.
crobatoJSTARS wasn’t in GW1 by the way. It was in GW2.
crobatoThe F-18 should have relaxed stability already.
crobatoI pretty much agree with you on all that. In addition, the F-18E/F isn’t cheaper than the Strike Eagle. Boeing does not mind selling you one or the other, as they make both anyway.
crobatoDoesnt the Flanker have the exact 35° limitation? Anyway, I dont think giving the missile a few degrees less to turn justifies the loss in speed.
The Flanker should have a much higher limitation—if any. To do Kulbit or Cobra, you practically should not have any limitation at all. A little plane like the JF-17 is set at 40 deg. I’ve heard about Hornets going well over 50 deg.
Thats true, but I wouldnt describe the F-16s upgrades as incremental compared to the F-15s.
How is that? The F-16s have to end up using a larger variety of wares than the F-15. For example use of Harpoons. Only F-15 that does that is the Korean ones. Many export F-16s were Harpoon capable since the mid nineties.
Since the A-10 with its very simple avionics is able to use the Maverick, I assumed displaying the image on the MFD (F-15 has only one) cant be that hard.
But the F-15 was never used in A/G roles so thats a theoretical thing. 🙂
The A-10 does not have much of a radar, does not mean it is extensively wired for optical equipment. Anything designed for A/G roles need TV channels, which not only do you use the Maverick with, but also images from FLIR and so on. The F-15 A to D does not have any TV capability with its MFDs till the Strike Eagle.
crobatoGarry, you keep talking as if the HOJ in the Kh-22 is the norm for HOJ with every missile out there. I don’t agree, with reasons I already stated. I have never seen the ARM feature on the Kh-22 being referred to as HOJ either.
As stated, the purpose of the AAM is to go after the target aircraft first, and not engage extraneous sources.
Zare, its pretty certain that the fire control systems on the MiG-29 and the Su-27 require specific identification of the R-27T over the R-27R. In that sense, they would also require specific identification and support for the R-27AE in the fire control systems, you cannot just put an R-27AE on any plane that supports the R-27R and expect it to be used without any modification (unless the software is already built in in advance). Even in the West, planes using AMRAAM have to have software updates to enable them to use a newer version of the AMRAAM.
crobatoFor carrier use, any airframe can be significantly beefed to that purpose, and the Eagle is one that is pretty tough, (and so is the Hornet) but the real clincher is whether or not the landing gear has enough travel to deal with carrier landings, which are essentially, controlled crashes. I don’t know if there is any space inside the F-15, or the F-16, for that matter, for a landing gear with sufficient travel in mind.
I have not seen an Eagle in a carrier really.
Northrop selling the T-38 and the F-5 to all sorts of small countries in the world, have to develop a plane with tough, long travel landing gear in mind. This experience is carried over to the YF-17. Despite the close results of the LFW competition that sided with the YF-16, the Navy was sufficiently impressed with the landing gear they saw on the YF-17, though the decision to go with the YF-17 -> F/A-18 over a navalized F-16 is probably colored with interservice and politically related rivalries as well.
F/A-18 is probably the kind of aircraft that I would see easier to deploy in makeshift bases in the front with rough landing and take off strips, something the Russians themselves are pretty good at.
crobatoI dont know how often and at what angle. Most aircraft are limited to around 35 degrees AoA and that seems to work fine.
I know that the Flanker and the Hornet are best known for their pointability. Pointability counts as much as imparting launching velocity on the misssile to give it the highest PK rates, mainly because, a missile travels best if it travels in the shortest and straightest path.
You are right. The only thing in common is the antenna and the power supply. They have added some addional modes too, thanks to increased memory. I dont know though how this affected general performance.
But I’d still say the F-16 has seen more radar upgrades.
Having more upgrades is not as important as the extent of the upgrades. What’s the difference of having smaller, more minute incremental upgrades performed more numerously than a few big massive overhaul type upgrades? In the end, its all the same, the final radar bears little to no resemblence from the original.
I’m really not sure about the Mavericks. But for the F-15As A/G stores, dumb bombs, LGBs and missiles are mentioned. I assume that means Maverick.
The use of Maverick requires extensive additions to the fire control systems, starting with having a TV channel, and having to display the real time images in one of the MFD. I don’t see this being done on the F-15A to D, until the Strike Eagles. Adding TV channel support on the F-16, MiG-29 and Su-27 (changed to -30) are not easy pancakes either.
crobatoFor RC model purposes, jet engines are usually of the pulse jet type, you know, kind of the same principle used on the V-1s. There are also miniture turbojets right now, with thrust up to 45lbs, but these are very expensive, at least in the 2000 to 4000 dollars price range per engine. The particular engine used on the J-10 appears to have a 3D vectoring nozzle, which shows you the kind of techs going into RC are pretty impressive.
It appears that the guy who made the J-10 RC may have contacted our own Deino once for pictures about the J-10.
crobatoGarry,
It does not change that HOJ and ARM are too different things. You keep trying to describe the Kh-22 as HOJ, when its more of a general ARM kind of usage. The main difference between HOJ and ARM is that HOJ basically works only against one particular jamming mode and that is particularly aimed at the missile itself. ARM works across a wide range of bands and targets, and does this by comparing the signals across a large signal library. HOJ does not have any library at all, it only works on the channel the missile is set in.
Zare,
SARH missiles work when the fighter radar is set on the STT mode (Single Target Tracking), which illuminates the target through continous wave illumination. ARH missiles on the other hand are supported through TWS or Track While Scan. STT does not allow you to engage multiple targets at once. Using STT, you can only guide one or two missiles against a single target, and in the scheme you just described, you can only ‘forget’ the missile once they are in terminal seeker range of the target.
Thus like Garry said, you would need a modification where the radar can datalink the coordinates to the missiles while the radar is in track while scan. If you put an AMRAAM seeker into a Sparrow, you still need to do the same thing.
Engaging more than one target is one of the main benefits of ARH. Since it is generally preferred that you can guide at least two missiles to a single target, once you are engaging at least two targets, you also need to upgrade the number of channels so you can now guide at least four missiles, two to each seperate target.
crobatoIts nice we have MiG-23MLD here to explain in great detail and obsfucate everyone. It really provides a crystal clear picture for the rest of us to appreciate.
crobato-
I’m pretty sure high AoA was not such a problem with the F-15, especially from the F-15C forward. The lerx is a low tech way of achieving what the F-15’s complicated air intake was designed. The real key of the F-15’s arrival was its brutish turning ability that was itself eclipsed by the F-16 and pretty much every air superiority and light fighter since. Few modern aircraft still match the F-15 in raw altitude performance, certainly not any of the light fighters, and the ones that do are even more specialized.
There is a reason why LERX is designed in the way you see it in the way now with a whole bunch of fighters today. I don’t think anyone out there agrees that a squared form is the ideal shape of a LERX. LERXs today are very carefully crafted and designed devices and working with vortices is a very delicate matter. The shape and the form of the vortices dictate if it is actually useful or detrimental as sheer turbulence.
In terms of raw speed and altitude, few can match the F-15. However, the majority of aircombat is expected to take place around the low to medium altitudes, and at subsonic speeds. Rather than being a jack of all trades when it comes to A2A, the F-16 choose to focus on where it counts based on experience. The F-15 was already on the boards when many of the lessons from Vietnam have yet to be learned, but the F-16 came later fortitiously after these lessons were impressed.
As for Harpoons and Maverick, the F-15 wasn’t tasked with those for a reason. It was much cheaper and more effective logistically to put them on the true maritime and ground support aircraft, respectively. Its only after the dawn of the multi-role fighter that one would even consider it on an F-15, which both options are available on today’s F-15E if the consumer wants it integrated in. The F-15 was really only an air superiority fighter up until the F-15E.
Nothing wrong with being focused on one task. The F-15 was on its way to becoming a monster until John Boyd came and the entire concept was overhauled with his ideas, EM theories and KISS principles among them. The F-15 isn’t going to be the great plane it became if it wasn’t one of the corner personalities of the light weight mafia. One thing I like about the F-15 over the F-14 was that the F-15 was brutally and elegantly simple.
crobatoOn a stable non-fbw design, high AoA is a no-go area.
Imho, its for airshows anyway. It wasnt a design priority for most western fighters.
Yet it is often demonstrated by Hornets in getting their “kill”.
Well, the F-16 got a new radar with several upgrades, the F-15 still has the same one with MSIP upgrade. Though im not sure how much A/A performance was improved with MSIP.
The F-15 does not have the same radar as it once was. First the APG-70 is a new radar from the APG-63. The APG-63V1 is a complete electronic overhaul over the APG-63, and the only thing they have in common is probably the mechanical antenna. If you understand a bit of electronics design, you don’t mix old and new.
But thats A/G stuff for upgraded F-16As. The F-15 got none of this because it wasnt needed.
I think F-15A is Maverick capable anyway.
I don’t recall the F-15A to be Maverick capable. I don’t think it ever was. Only the Strike Eagle and that was only some time later well after the plane was introduced. Even then, upgrades to the F-16s brought more options that the Eagle didn’t have until the Slam Eagle only of late.
crobatocrobato, that site where i’ve seen the supposed Su-27SK/R-27AE picture is now missing it’s images (some hosting tags instead). However, there’s visual difference between R-27ER and R-27AE, RE has more curved nose, while AE has shorter, more sharp, coned one, and R-27AE has two rings on the intersection between seeker module and main body.
Exactly why I always save interesting pics when i see them.
With modular nature of R-27 family, how hard is to use the “E” long-burn body, and fit it AGAT’s active seeker?
Not much. You do have to modify the fighter’s radar and fire control system though.
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