By: Vortex
- 15th January 2002 at 00:12Permalink- Edited 1st January 1970 at 01:00
RE: return to the question
no problem Ink, i was merely addressing to your "needs" in terms of what happens under your proposed conditions. But, as to Garry, i'm starting to wonder about his computer something degree. What part of self healing and modulating built in tests doesn't he understand. For example, if certain component of the radar is malfunctioning, the build in algorithm will try to re-route the problem and come up with the most combat effective set up. So, unless every component is fried, the onboard computer will try it's best to maintain as high a level of combat readiness as possible. But, Garry is referring more to the 20-30 years old technology where it simply just tell you where the computer think it's broken. Very very different thing and very very different level of technology. For example GARRY, when a certain part in the radar system is down, it is very likely to bypass it if that component is part of the fault tolerant sub system. In that case the radar will continue to operate. This kind of design is very much in the state of the art. IE, most of the F-22's computer uses subsystem boards that are totally identical and redundant. The only difference is the software. When one fails, the other boards will start to divide the load up and redownload the necessary software from each other. Of course there are some loss of capability, but 80% combat effective is better than 0%. Garry tends to like to be extreme when it suits his views. Just to keep your Jaws dropped GARRY, the next generation will utilize hardware IC reroute technologies instead of software reroute. This means that even more capability can be restored when other systems failed. Think of it as a EEPROMED CPU operating at CPU speeds...even scarrier, think of it as the beginning of true hardware artificial intellegence.
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By: Anonymous
- 16th January 2002 at 03:13Permalink- Edited 16th October 2019 at 10:05
RE: return to the question
[updated:LAST EDITED ON 16-01-02 AT 03:18 AM (GMT)]"What part of self healing and modulating built in tests doesn't he understand. "
Self healing and bypassing are two very different things. If your arm stops working and you continue working by using the other arm have you "Self healed"? No of course not. If an aircraft is properly maintained and serviced the likelyhood of a total failure is almost zero unless there is something seriously wrong with its design or fabrication. Unless your enemy starts using weapons that will only knock out small components one at a time this stuff is US technology driven BS. The last time I looked the threats to an aircraft were the ground, other fighters firing missiles and guns, and ground fire.
This whole idea seems to me to be an attemt to save a little money by not replacing parts until they fail. This means for the money you save the likelyhood of your pilots getting airborne and things failing actually increases.
"Of course there are some loss of capability, but 80% combat effective is better than 0%."
Ummm Vortex, I know about that sort of stuff, and it is not really a new concept. One of the reasons the Russians decided to put a phased array radar in their Mig-31 was because of the fact that if one array element fails the fighter can still do its job. Its call graceful decay or something.
My point which you seem to be trying to ignore is that it doesn't matter how well a system bypasses non-functioning units, if nothing is getting serviced or is receiving spare parts then eventually nothing will be working. And 80% is not better than the 100% of an aircraft that out performs it and is maintained properly.
(The F-18CD has never been touted as a superfighter, if the SH is behind in a few area and its performance is dropped by 20% you are looking at a second class bird.)
Said it before and I'll say it again the SH is an accountants plane.
By: Vortex
- 16th January 2002 at 03:48Permalink- Edited 1st January 1970 at 01:00
RE: return to the question
Garry, i don't know how much of this is your added BS. the Mig-31's phase array radar is not active arrays, that technically means it CAN NOT perform like an active array's independent module operations. Please Garry don't confuse people here on it. If your TV's tube is burned out, it's BURNED OUT. If a couple pixels on your LCD is burned out, well, you still got lots left.
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By: Anonymous
- 16th January 2002 at 23:10Permalink- Edited 16th October 2019 at 10:05
RE: return to the question
The Phased array radar is based on an array of active elements that can be switched on and off independantly. The only alternative would be to switch them all on and off at the same time, and when one fails they all fail.
This alternative makes little sense and would be far more expensive than a standard radar with a dish.
As you know:
(With two engines you increase the safety of flight because the likelyhood of one engine failing is say 0.00001% per flight hour assuming proper maintainence, so the liklyhood of both engines failing is 0.00001 x 0.00001 = 0.000000... ie it is much lower.
With a phased array that fails with the failure of one element then the failure probabilities are added together, not multiplied, so risk of failure is increased by a rather large margin, not reduced.)
Strange they can't manage to make active phased arrays... I guess those phased arrays they use for their SAMs like SA-10, SA-12, and the mobile tracked SA-15 are just painted on.
The radar for the new Su-32 prototype has a very similar though different shaped antenna, I guess they still don't have any?
By: Vortex
- 17th January 2002 at 19:05Permalink- Edited 1st January 1970 at 01:00
RE: return to the question
that's right Garry, you're very smart. Now you know why the fuss with getting each element to generate it's own waveforms and receive directly instead of feeding off from the main radiation source like the Russian radars and the first generation Rafale phased arrays. I didn't say the Russians can't make any active and independent elements of a phased array radar, but the capabilities will come from how much they can miniaturize each element. Those radars you've shown uses one source and then electronically switched them to the wave guides to create a phased array steering effect. What we are talking about is take each of what you've shown on the Russian aircraft, shrink it down and them group them together to 500-1000 elements (or so). That means each element can be blown to pieces (or fail) and the weak point becomes the powersupply, not the RF generator. but, if you lose power on almost any FBW plane that's GAME OVER. Again as to your computer degree, you should know better about fault tolerant designs.
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By: Anonymous
- 18th January 2002 at 04:38Permalink- Edited 16th October 2019 at 10:05
RE: return to the question
"Those radars you've shown uses one source and then electronically switched them to the wave guides to create a phased array steering effect. What we are talking about is take each of what you've shown on the Russian aircraft, shrink it down and them group them together to 500-1000 elements (or so)."
I don't think you understand.
A phased array is literally an array or transceivers that are in phase... ie work together. Each element transmits and receives an electronic signal. The only difference between the Russian system on the Mig-31 and the new AESA radar is that the Russian system didn't have active beam forming algorithms to optimise the signals for LPI, and specific targets or atmospheric conditions. The -31 radar used (radar) mirrors to extend the radar coverage several times the volume of a normal radar like for instance the set on the F-14D. The extra processing for this meant processing power, which was already marginal for the purpose was not sufficient for beam shaping and other sophisticated techniques. Different frequencies could be used (ie frequencies for looking up or down and for long and short range targets could be used simultaneously by different elements, so if it had a ground mapping/following function the lower elements could be performing that function, with upper elements performing air search for threats. For conventional radars two different radars would be required for the simultaneous use of both "modes".)
Compare the Su-34 radar above which as a land and sea strike aircraft needs simultaneous airsearch and ground search capabilities, with that below of the Su-24 with two radar dishes...
By: Vortex
- 18th January 2002 at 23:22Permalink- Edited 1st January 1970 at 01:00
Unless i'm wrong...
Garry, the confusion here is that Phased Arrays can mean a lot of things. For the Russian case, it literally means Slotted Phased Array Antennas instead of Radar systems. AESA is what we call a radar system when every antenna has it's own Tx/Rx set and control algorithms (like a MIMIC module). Why do you think the Russian a/c's antenna is slotted...while the AESA radars (or similar, ie Ericson's AEW) is a flush mount. Don't tell me that's it's plain cosmetics, because it's not.
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By: Anonymous
- 19th January 2002 at 10:49Permalink- Edited 16th October 2019 at 10:05
RE: Unless i'm wrong...
[updated:LAST EDITED ON 19-01-02 AT 10:51 AM (GMT)]"Don't tell me that's it's plain cosmetics, because it's not."
Active beam forming is not a cosmetic difference, but the Radar on the Mig-31 is not a plain slotted antenna like on a Mig-29, or Su-27.
It is literally an array or elements that transmit and receive radar waves. In the picture above of the Su-24 nose there are two Transceivers... each facing backwards toward the dish. The reflected signal also hits the dish and is returned to the tranceiver which records the reception of the signal and its frequency etc and this is processed in a computer to determine whether it is useful information or noise. (For the ground mapping radar any air contacts is noise... of course in terrain avoidance mode air targets need to be avoided and become information, for the air search radar any mountains in the distance is noise.)
To get reasonable coverage in front of the aircraft the dish moves.
More modern aircraft use flat slotted antennas that can be slewed to give wider coverage, but are not Phased arrays.
The Phased array set used on the Mig-31 has an array of fixed transceivers that have their beams "scanned" by mirrors behind them. The reason the Russian system looks different is because the "Tx/Rx" are facing rearward. The static "Tx/Rx" are much more stable but without the mirrors would have a rediculously narrow field of view. (The sidelobes for Phased arrays are very small, which as you probably know is a good thing.)
Being an active array any element can be flicked on and off very quickly to check if a target is still following the same course rather than continously lighting the target up with an easily detectible beam. The short flash may not be noticed or may be considered an error.
The alternative to using mirrors would be to fit the entire array onto a moving flate plate that is pointed like a normal radar. the problems of scan rate (ie now based on pointing speed) plus bulk and a reduction in the size of the width of the radar are penalties for such a design solution.
By: Vortex
- 19th January 2002 at 19:05Permalink- Edited 1st January 1970 at 01:00
RE: Unless i'm wrong...
why scanning mirror? A true AESA in western terms has no moving parts. And no, it's not the same thing with what you say about not using a mirror and making it look like a regular radar. Remember again, the Russians are rather capable mechanics, not electronics (yeah you're probably sick and tire of this, but i'm just trying to rub it in until you recognize). The mirrors are rather more of being "switches". By using multiple switchings, then a phased relationship between each transmitting wave (again , not the same thing as a phsical RF generator or source) can be put too use. Let me put it this way, each element on an AESA can be taken out and then used alone. In order to do that and perform as a group, the phase relationship of the transmitting waves must be known. A easier, but less effective, way is to use a single source and using standing waves. That way each wave is known and all other "transmitted" wave is based on the original wave (kinda like a interferometer).
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By: Anonymous
- 20th January 2002 at 10:25Permalink- Edited 16th October 2019 at 10:05
RE: Unless i'm wrong...
Not a scanning mirror, scanning mirrors... one for each tranceiver.
It increases the volume of airspace that can be scanned by a rather large margin. Each emitter/receiver can be used independantly too, and with the pointability of the mirror behind them each one can cover the same front hemisphere area that any other element can cover.
"The mirrors are rather more of being "switches"."
No, the mirrors are acting like mirrors and directing the radar beams over a wider field of regard than would be possible without them and using fixed emmiting elements. The volume of radar coverage for the Mig-31 is about 10 times greater than say the coverage of the F-14 radar despite the shorter range. This is due to very small sidelobes and wide field of regard due to the use of mirrors.
By: Vortex
- 20th January 2002 at 23:47Permalink- Edited 1st January 1970 at 01:00
Garry...
you are one stubborn piece of @#$@#$
like i said, the mirrors on an AESA is not a mirror that you think off like in the Russian radars. There are no mirrors there, but electronically scanned. It can scan at least 60 degrees(heard of up to 80) from normal at each side without ANY MOVING PARTS instead of the stupid physical mirrors that the Russians used. Geezes, either you are really really having fun with this or just plain " " (fill in the blank yourself, ie, "stupid".)
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By: Anonymous
- 21st January 2002 at 23:00Permalink- Edited 16th October 2019 at 10:05
RE: Vortex
[updated:LAST EDITED ON 21-01-02 AT 11:02 PM (GMT)]No, I am not stupid.
Electronically scanned could also be used to describe the Russian set as well.
That is how phased arrays work.
Instead of a dish slewing from left to right and back again the elements are activated from left to right (or right to left). These can be elements along the top of the array to look up or along the bottom of the array with a ground search function and using frequencies approprate for ground mapping.
The Russian radar does that too, but it uses mirrors to greatly increase the view angles and therefore also greatly increase the volume of space it can search.
The purpose of the Mig-31 is to intercept bombers and cruise missiles so the volume of airspace it can search is more important than range.
If it detects a B-1 at medium altitude which has just fired a cruise missile, the latter having dropped down to 15m, the Mig needs to be able to look up and down at the same time. With a conventional radar this would be a problem. (An F-14 would have to take them on one at a time or assign one F-14 for high targets and one F-14 for low targets.)
BTW
"you are one stubborn piece of @#$@#$"
Please keep the name calling to yourself.
"...like i said, the mirrors on an AESA is not a mirror that you think off like in the Russian radars."
If you read my posts above, I have not been telling you about the AESA radar, but about the Mig radar so I really don't know what you are talking about.
If you are going to ignore what I write that is fine, but please do not call me a stubborn piece of anything because of your misinterpretations.
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Posts: 90
By: follandGnat
- 27th January 2002 at 21:49Permalink- Edited 1st January 1970 at 01:00
more on tomcat
Sorry to drag this thread out again,but what is the thrust to weight ratio of a tomcat?I think that a 1 to 1 ratio would make this jet a dogfighter beyond that of even the F-15.The fact that this jet is on the heavy side and lacks vertical acceleration is the ONLY thing that has held this jet back.
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Posts: 1,404
By: Sauron
- 27th January 2002 at 23:42Permalink- Edited 1st January 1970 at 01:00
RE: more on tomcat
The F-14D weighs in at 43.7K. Add 16.2K of fuel plus an air-to-air weapons load of say 5-6K and it launchs at approx 66K. With the two F-110-GE-400 generating 56.4K in AB, you are a little short of 1:1 until you are going home.
Regards
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By: Anonymous
- 28th January 2002 at 02:00Permalink- Edited 16th October 2019 at 10:05
RE: more on tomcat
The decision for heavy fighter in US between F-15 and F-14 was rather more political than anything to do with capability.
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By: Anonymous
- 29th January 2002 at 22:15Permalink- Edited 1st January 1970 at 01:00
RE: more on tomcat
Yes, one wanted a Vette and the other a Viper. Daddy had more money than he knew what to do with. So, they both got there toys for christmas! Unfortunately, the American taxpayer got the bill!!! (and don't get me started with the F-16 and F/A-18 either)
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By: Anonymous
- 30th January 2002 at 00:06Permalink- Edited 16th October 2019 at 10:05
RE: more on tomcat
"(and don't get me started with the F-16 and F/A-18 either)"
Tell me what Scooter, I'm interested in what your opinion is.
(This is a discussion board after all.)
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Posts: 2,907
By: Rabie
- 30th January 2002 at 00:18Permalink- Edited 1st January 1970 at 01:00
not here
it takes ages to press the thread then click on each new post in turn -do it elsewhere - 100+ post are too hard too look at.
:-)
rant over -intresting topic though
rabie :9
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By: Anonymous
- 30th January 2002 at 17:03Permalink- Edited 1st January 1970 at 01:00
RE: more on tomcat
GarryB- Basically, the U.S. goverment spent billions of dollars to developed four fighters when it really only needed two! I believe in a good high low mix but, did every service need a aircraft of there own? They should have developed one twin engined fighter for Air Defence and Air Superiority and a single engined fighter for Attack and Strike roles. Something like a F-14 and F-16 mix with the same engines and similar avionics. Look and what the support and logistics saving they would be alone! Oh, I am sure that I'll hear from many supporters of the other designs! Thought, in reality is there much deference in proformance between the four? All over the world these four aircraft fly ACM mission against each other. Do you think that any of the aircraft I've listed has a big advantage over the others? No! Maybe some have a slight edge in this or that but, when you take in factors like experience, traning, and numbers (to name a few). There pretty close! Same problem today. Look the Navy is spending more money to develop the Super Hornet than it would take to purchase a Naval version of the F-22! Wouldn't the Services and Taxpayers be better serviced by a Hi-Low Mix of F-22's and JSF's for both the Air Force and Navy! It worked with the F-4 in the 60's, 70's and 80's! Why not now.............
Scooter
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Posts: 2,907
By: Rabie
- 30th January 2002 at 18:52Permalink- Edited 1st January 1970 at 01:00
RE: more on tomcat
simply becaus ethe c0ck up that was the f-111. adrmil tomcat's "there isn't enoguh thrust in christendom" speach, etc ring any bells.
the f4 and a7 made great land planes because they were navalplanes to start with - to work the other way is inherintly difficult and results have been poor or catostrophic (think f-111b, seafire, f-18, etc).
any way the JSF if it works should broing about the magical solutions - keep your fingers crossed.
Posts: 3,131
By: Vortex - 15th January 2002 at 00:12 Permalink - Edited 1st January 1970 at 01:00
RE: return to the question
no problem Ink, i was merely addressing to your "needs" in terms of what happens under your proposed conditions. But, as to Garry, i'm starting to wonder about his computer something degree. What part of self healing and modulating built in tests doesn't he understand. For example, if certain component of the radar is malfunctioning, the build in algorithm will try to re-route the problem and come up with the most combat effective set up. So, unless every component is fried, the onboard computer will try it's best to maintain as high a level of combat readiness as possible. But, Garry is referring more to the 20-30 years old technology where it simply just tell you where the computer think it's broken. Very very different thing and very very different level of technology. For example GARRY, when a certain part in the radar system is down, it is very likely to bypass it if that component is part of the fault tolerant sub system. In that case the radar will continue to operate. This kind of design is very much in the state of the art. IE, most of the F-22's computer uses subsystem boards that are totally identical and redundant. The only difference is the software. When one fails, the other boards will start to divide the load up and redownload the necessary software from each other. Of course there are some loss of capability, but 80% combat effective is better than 0%. Garry tends to like to be extreme when it suits his views. Just to keep your Jaws dropped GARRY, the next generation will utilize hardware IC reroute technologies instead of software reroute. This means that even more capability can be restored when other systems failed. Think of it as a EEPROMED CPU operating at CPU speeds...even scarrier, think of it as the beginning of true hardware artificial intellegence.
By: Anonymous - 16th January 2002 at 03:13 Permalink - Edited 16th October 2019 at 10:05
RE: return to the question
[updated:LAST EDITED ON 16-01-02 AT 03:18 AM (GMT)]"What part of self healing and modulating built in tests doesn't he understand. "
Self healing and bypassing are two very different things. If your arm stops working and you continue working by using the other arm have you "Self healed"? No of course not. If an aircraft is properly maintained and serviced the likelyhood of a total failure is almost zero unless there is something seriously wrong with its design or fabrication. Unless your enemy starts using weapons that will only knock out small components one at a time this stuff is US technology driven BS. The last time I looked the threats to an aircraft were the ground, other fighters firing missiles and guns, and ground fire.
This whole idea seems to me to be an attemt to save a little money by not replacing parts until they fail. This means for the money you save the likelyhood of your pilots getting airborne and things failing actually increases.
"Of course there are some loss of capability, but 80% combat effective is better than 0%."
Ummm Vortex, I know about that sort of stuff, and it is not really a new concept. One of the reasons the Russians decided to put a phased array radar in their Mig-31 was because of the fact that if one array element fails the fighter can still do its job. Its call graceful decay or something.
My point which you seem to be trying to ignore is that it doesn't matter how well a system bypasses non-functioning units, if nothing is getting serviced or is receiving spare parts then eventually nothing will be working. And 80% is not better than the 100% of an aircraft that out performs it and is maintained properly.
(The F-18CD has never been touted as a superfighter, if the SH is behind in a few area and its performance is dropped by 20% you are looking at a second class bird.)
Said it before and I'll say it again the SH is an accountants plane.
Posts: 3,131
By: Vortex - 16th January 2002 at 03:48 Permalink - Edited 1st January 1970 at 01:00
RE: return to the question
Garry, i don't know how much of this is your added BS. the Mig-31's phase array radar is not active arrays, that technically means it CAN NOT perform like an active array's independent module operations. Please Garry don't confuse people here on it. If your TV's tube is burned out, it's BURNED OUT. If a couple pixels on your LCD is burned out, well, you still got lots left.
By: Anonymous - 16th January 2002 at 23:10 Permalink - Edited 16th October 2019 at 10:05
RE: return to the question
The Phased array radar is based on an array of active elements that can be switched on and off independantly. The only alternative would be to switch them all on and off at the same time, and when one fails they all fail.
This alternative makes little sense and would be far more expensive than a standard radar with a dish.
As you know:
(With two engines you increase the safety of flight because the likelyhood of one engine failing is say 0.00001% per flight hour assuming proper maintainence, so the liklyhood of both engines failing is 0.00001 x 0.00001 = 0.000000... ie it is much lower.
With a phased array that fails with the failure of one element then the failure probabilities are added together, not multiplied, so risk of failure is increased by a rather large margin, not reduced.)
Strange they can't manage to make active phased arrays... I guess those phased arrays they use for their SAMs like SA-10, SA-12, and the mobile tracked SA-15 are just painted on.
The radar for the new Su-32 prototype has a very similar though different shaped antenna, I guess they still don't have any?
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Posts: 3,131
By: Vortex - 17th January 2002 at 19:05 Permalink - Edited 1st January 1970 at 01:00
RE: return to the question
that's right Garry, you're very smart. Now you know why the fuss with getting each element to generate it's own waveforms and receive directly instead of feeding off from the main radiation source like the Russian radars and the first generation Rafale phased arrays. I didn't say the Russians can't make any active and independent elements of a phased array radar, but the capabilities will come from how much they can miniaturize each element. Those radars you've shown uses one source and then electronically switched them to the wave guides to create a phased array steering effect. What we are talking about is take each of what you've shown on the Russian aircraft, shrink it down and them group them together to 500-1000 elements (or so). That means each element can be blown to pieces (or fail) and the weak point becomes the powersupply, not the RF generator. but, if you lose power on almost any FBW plane that's GAME OVER. Again as to your computer degree, you should know better about fault tolerant designs.
By: Anonymous - 18th January 2002 at 04:38 Permalink - Edited 16th October 2019 at 10:05
RE: return to the question
"Those radars you've shown uses one source and then electronically switched them to the wave guides to create a phased array steering effect. What we are talking about is take each of what you've shown on the Russian aircraft, shrink it down and them group them together to 500-1000 elements (or so)."
I don't think you understand.
A phased array is literally an array or transceivers that are in phase... ie work together. Each element transmits and receives an electronic signal. The only difference between the Russian system on the Mig-31 and the new AESA radar is that the Russian system didn't have active beam forming algorithms to optimise the signals for LPI, and specific targets or atmospheric conditions. The -31 radar used (radar) mirrors to extend the radar coverage several times the volume of a normal radar like for instance the set on the F-14D. The extra processing for this meant processing power, which was already marginal for the purpose was not sufficient for beam shaping and other sophisticated techniques. Different frequencies could be used (ie frequencies for looking up or down and for long and short range targets could be used simultaneously by different elements, so if it had a ground mapping/following function the lower elements could be performing that function, with upper elements performing air search for threats. For conventional radars two different radars would be required for the simultaneous use of both "modes".)
Compare the Su-34 radar above which as a land and sea strike aircraft needs simultaneous airsearch and ground search capabilities, with that below of the Su-24 with two radar dishes...
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Posts: 3,131
By: Vortex - 18th January 2002 at 23:22 Permalink - Edited 1st January 1970 at 01:00
Unless i'm wrong...
Garry, the confusion here is that Phased Arrays can mean a lot of things. For the Russian case, it literally means Slotted Phased Array Antennas instead of Radar systems. AESA is what we call a radar system when every antenna has it's own Tx/Rx set and control algorithms (like a MIMIC module). Why do you think the Russian a/c's antenna is slotted...while the AESA radars (or similar, ie Ericson's AEW) is a flush mount. Don't tell me that's it's plain cosmetics, because it's not.
By: Anonymous - 19th January 2002 at 10:49 Permalink - Edited 16th October 2019 at 10:05
RE: Unless i'm wrong...
[updated:LAST EDITED ON 19-01-02 AT 10:51 AM (GMT)]"Don't tell me that's it's plain cosmetics, because it's not."
Active beam forming is not a cosmetic difference, but the Radar on the Mig-31 is not a plain slotted antenna like on a Mig-29, or Su-27.
It is literally an array or elements that transmit and receive radar waves. In the picture above of the Su-24 nose there are two Transceivers... each facing backwards toward the dish. The reflected signal also hits the dish and is returned to the tranceiver which records the reception of the signal and its frequency etc and this is processed in a computer to determine whether it is useful information or noise. (For the ground mapping radar any air contacts is noise... of course in terrain avoidance mode air targets need to be avoided and become information, for the air search radar any mountains in the distance is noise.)
To get reasonable coverage in front of the aircraft the dish moves.
More modern aircraft use flat slotted antennas that can be slewed to give wider coverage, but are not Phased arrays.
The Phased array set used on the Mig-31 has an array of fixed transceivers that have their beams "scanned" by mirrors behind them. The reason the Russian system looks different is because the "Tx/Rx" are facing rearward. The static "Tx/Rx" are much more stable but without the mirrors would have a rediculously narrow field of view. (The sidelobes for Phased arrays are very small, which as you probably know is a good thing.)
Being an active array any element can be flicked on and off very quickly to check if a target is still following the same course rather than continously lighting the target up with an easily detectible beam. The short flash may not be noticed or may be considered an error.
The alternative to using mirrors would be to fit the entire array onto a moving flate plate that is pointed like a normal radar. the problems of scan rate (ie now based on pointing speed) plus bulk and a reduction in the size of the width of the radar are penalties for such a design solution.
Posts: 3,131
By: Vortex - 19th January 2002 at 19:05 Permalink - Edited 1st January 1970 at 01:00
RE: Unless i'm wrong...
why scanning mirror? A true AESA in western terms has no moving parts. And no, it's not the same thing with what you say about not using a mirror and making it look like a regular radar. Remember again, the Russians are rather capable mechanics, not electronics (yeah you're probably sick and tire of this, but i'm just trying to rub it in until you recognize). The mirrors are rather more of being "switches". By using multiple switchings, then a phased relationship between each transmitting wave (again , not the same thing as a phsical RF generator or source) can be put too use. Let me put it this way, each element on an AESA can be taken out and then used alone. In order to do that and perform as a group, the phase relationship of the transmitting waves must be known. A easier, but less effective, way is to use a single source and using standing waves. That way each wave is known and all other "transmitted" wave is based on the original wave (kinda like a interferometer).
By: Anonymous - 20th January 2002 at 10:25 Permalink - Edited 16th October 2019 at 10:05
RE: Unless i'm wrong...
Not a scanning mirror, scanning mirrors... one for each tranceiver.
It increases the volume of airspace that can be scanned by a rather large margin. Each emitter/receiver can be used independantly too, and with the pointability of the mirror behind them each one can cover the same front hemisphere area that any other element can cover.
"The mirrors are rather more of being "switches"."
No, the mirrors are acting like mirrors and directing the radar beams over a wider field of regard than would be possible without them and using fixed emmiting elements. The volume of radar coverage for the Mig-31 is about 10 times greater than say the coverage of the F-14 radar despite the shorter range. This is due to very small sidelobes and wide field of regard due to the use of mirrors.
Posts: 3,131
By: Vortex - 20th January 2002 at 23:47 Permalink - Edited 1st January 1970 at 01:00
Garry...
you are one stubborn piece of @#$@#$
like i said, the mirrors on an AESA is not a mirror that you think off like in the Russian radars. There are no mirrors there, but electronically scanned. It can scan at least 60 degrees(heard of up to 80) from normal at each side without ANY MOVING PARTS instead of the stupid physical mirrors that the Russians used. Geezes, either you are really really having fun with this or just plain " " (fill in the blank yourself, ie, "stupid".)
By: Anonymous - 21st January 2002 at 23:00 Permalink - Edited 16th October 2019 at 10:05
RE: Vortex
[updated:LAST EDITED ON 21-01-02 AT 11:02 PM (GMT)]No, I am not stupid.
Electronically scanned could also be used to describe the Russian set as well.
That is how phased arrays work.
Instead of a dish slewing from left to right and back again the elements are activated from left to right (or right to left). These can be elements along the top of the array to look up or along the bottom of the array with a ground search function and using frequencies approprate for ground mapping.
The Russian radar does that too, but it uses mirrors to greatly increase the view angles and therefore also greatly increase the volume of space it can search.
The purpose of the Mig-31 is to intercept bombers and cruise missiles so the volume of airspace it can search is more important than range.
If it detects a B-1 at medium altitude which has just fired a cruise missile, the latter having dropped down to 15m, the Mig needs to be able to look up and down at the same time. With a conventional radar this would be a problem. (An F-14 would have to take them on one at a time or assign one F-14 for high targets and one F-14 for low targets.)
BTW
"you are one stubborn piece of @#$@#$"
Please keep the name calling to yourself.
"...like i said, the mirrors on an AESA is not a mirror that you think off like in the Russian radars."
If you read my posts above, I have not been telling you about the AESA radar, but about the Mig radar so I really don't know what you are talking about.
If you are going to ignore what I write that is fine, but please do not call me a stubborn piece of anything because of your misinterpretations.
Posts: 90
By: follandGnat - 27th January 2002 at 21:49 Permalink - Edited 1st January 1970 at 01:00
more on tomcat
Sorry to drag this thread out again,but what is the thrust to weight ratio of a tomcat?I think that a 1 to 1 ratio would make this jet a dogfighter beyond that of even the F-15.The fact that this jet is on the heavy side and lacks vertical acceleration is the ONLY thing that has held this jet back.
Posts: 1,404
By: Sauron - 27th January 2002 at 23:42 Permalink - Edited 1st January 1970 at 01:00
RE: more on tomcat
The F-14D weighs in at 43.7K. Add 16.2K of fuel plus an air-to-air weapons load of say 5-6K and it launchs at approx 66K. With the two F-110-GE-400 generating 56.4K in AB, you are a little short of 1:1 until you are going home.
Regards
By: Anonymous - 28th January 2002 at 02:00 Permalink - Edited 16th October 2019 at 10:05
RE: more on tomcat
The decision for heavy fighter in US between F-15 and F-14 was rather more political than anything to do with capability.
By: Anonymous - 29th January 2002 at 22:15 Permalink - Edited 1st January 1970 at 01:00
RE: more on tomcat
Yes, one wanted a Vette and the other a Viper. Daddy had more money than he knew what to do with. So, they both got there toys for christmas! Unfortunately, the American taxpayer got the bill!!! (and don't get me started with the F-16 and F/A-18 either)
By: Anonymous - 30th January 2002 at 00:06 Permalink - Edited 16th October 2019 at 10:05
RE: more on tomcat
"(and don't get me started with the F-16 and F/A-18 either)"
Tell me what Scooter, I'm interested in what your opinion is.
(This is a discussion board after all.)
Posts: 2,907
By: Rabie - 30th January 2002 at 00:18 Permalink - Edited 1st January 1970 at 01:00
not here
it takes ages to press the thread then click on each new post in turn -do it elsewhere - 100+ post are too hard too look at.
:-)
rant over -intresting topic though
rabie :9
By: Anonymous - 30th January 2002 at 17:03 Permalink - Edited 1st January 1970 at 01:00
RE: more on tomcat
GarryB- Basically, the U.S. goverment spent billions of dollars to developed four fighters when it really only needed two! I believe in a good high low mix but, did every service need a aircraft of there own? They should have developed one twin engined fighter for Air Defence and Air Superiority and a single engined fighter for Attack and Strike roles. Something like a F-14 and F-16 mix with the same engines and similar avionics. Look and what the support and logistics saving they would be alone! Oh, I am sure that I'll hear from many supporters of the other designs! Thought, in reality is there much deference in proformance between the four? All over the world these four aircraft fly ACM mission against each other. Do you think that any of the aircraft I've listed has a big advantage over the others? No! Maybe some have a slight edge in this or that but, when you take in factors like experience, traning, and numbers (to name a few). There pretty close! Same problem today. Look the Navy is spending more money to develop the Super Hornet than it would take to purchase a Naval version of the F-22! Wouldn't the Services and Taxpayers be better serviced by a Hi-Low Mix of F-22's and JSF's for both the Air Force and Navy! It worked with the F-4 in the 60's, 70's and 80's! Why not now.............
Scooter
Posts: 2,907
By: Rabie - 30th January 2002 at 18:52 Permalink - Edited 1st January 1970 at 01:00
RE: more on tomcat
simply becaus ethe c0ck up that was the f-111. adrmil tomcat's "there isn't enoguh thrust in christendom" speach, etc ring any bells.
the f4 and a7 made great land planes because they were navalplanes to start with - to work the other way is inherintly difficult and results have been poor or catostrophic (think f-111b, seafire, f-18, etc).
any way the JSF if it works should broing about the magical solutions - keep your fingers crossed.
rabie :9