Operational Performace Comparison: Viper, Beagle, and Stubby

The F-35 compared with other modern jets.
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swiss

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Unread post27 Jul 2019, 14:25

sprstdlyscottsmn wrote:
wrightwing wrote:The Irbis manufacturer claims 170km in look down mode vs 3m^2 target, and 190km in look up mode. The 350 to 400km claim, is for a 10° × 10° cued search. All of those ranges would have to be adjusted significantly for a 90% detection probability vs a 1m^2 target.

I have not been able to find anything to support this even googling "Irbis-E 190km" the closest I have come is below

"The Zhuk-MSF / Sokol-3 from the Phazotron NIIR OKB

Zhuk-MSF is the most up to date radar design by Phazotron. Sokol uses a non-equidistant rather than the traditional linear radar field distribution, which, Phazotron says, allows a fivefold radar cost reduction over a traditionally designed phased array radar. The production radar will have a 980mm antenna diameter (37dB gain) and weigh 275kg. The radar tracks 24-30 targets, engages the most dangerous 6 to 8 of them. Its electronic beam steering will give ±70 deg spatial coverage in both axes. Power output is 8kW peak, 2 - 3kW average. It is designed for high reliability, and is frequency agile with LPI and anti ECM features. Phazotron says it will be capable of interleaving between air-to-air and air-to-ground modes.

Velocity search: 245km head-on vs fighter target.(This figure is no longer quoted. The mode may have been removed)

Range-while-search, lookup mode: 180-190km head-on / 80km tail-on vs fighter target.

Range-while-search, lookdown mode : 170km head-on / 60km tail-on vs fighter target.

Track-while-scan mode: 150km head-on vs fighter target.

Against a large target such as a bomber or AWACS aircraft detection range comfortably exceeds 300km. "

Edit* Even at https://www.niip.ru/catalog/eksportnaya ... u-irbis-e/ I only see the narrow search value.


Range in Volume search is 200km vs a 3m2 Target according to the UAC page about the Su-35.

https://www.uacrussia.ru/en/aircraft/li ... n-features

The most important difference between the Su-35 and ”4+” generation fighters is its fifth-generation avionics. The Irbis-E radar station with rotating phased antenna array designed by the V. Tikhomirov Research Institute of Instrumentation provides for the assured detection and acquisition of typical aerial targets at a range of up to 200 km (up to 170 km against ground background), and in a narrower field of view¬ – up to 350-400 km. The Irbis-E is able to track up to 30 targets at a time and guide missiles at 8 of them, without an interruption in airspace surveillance. The radar control system also provides for the selective acquisition of moving ground targets and cueing for low-level missions.


The APG-83 has over 30 % more Range compere to the APG-66v3 (90km range). So we talk about over 120km vs 5m3 target.

https://airforcesmonthly.keypublishing. ... ight-test/

The AN/APG-83 can simultaneously perform search, tracking and lock-on functions. For multiple targets, the detection range is increased by more than 30% compared with the original APG-66(V)3 radar.
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Unread post27 Jul 2019, 15:39

Thank you. I will adjust the Irbis and APG-83 accordingly. This will cause me to re-run the CAP scenario.
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Unread post27 Jul 2019, 21:06

sprstdlyscottsmn wrote:III) I wish someone in the know could tell me what the problems were the APG-79 had and if they related to range at all. I am thinking I will restore it to 111/86nm since nothing I have seen actually says it impacted range.


The problems with the APG-79 seem to be mostly if not entirely related to reliability and (software) stability and in no way related to range (or having problems that impact the radar's detection range).

Read for example here:
https://www.flightglobal.com/news/artic ... re-204360/

The article above starts with the following which seems to pretty much resumes the APG-79 problems:
APG-79 praised, when it works, but shutdowns and restarts continue to frustrate


It also seems that most of these problems are related to software and the vast majority of these problems were reported by DOT&E during 2005-2007 which and as such, I would say that the chances that those issues are already and mostly solved by now should be least, very high.
A 4th/4.5th gen fighter aircraft stands about as much chance against a F-35 as a guns-only Sabre has against a Viper.
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Unread post27 Jul 2019, 22:00

swiss wrote:
The APG-83 has over 30 % more Range compere to the APG-66v3 (90km range). So we talk about over 120km vs 5m3 target.

https://airforcesmonthly.keypublishing. ... ight-test/

The AN/APG-83 can simultaneously perform search, tracking and lock-on functions. For multiple targets, the detection range is increased by more than 30% compared with the original APG-66(V)3 radar.

This is a significant step backwards from what I had. I had 215km v 5m^2 detection, 167km lock.
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Unread post27 Jul 2019, 23:02

sprstdlyscottsmn wrote:
swiss wrote:
The APG-83 has over 30 % more Range compere to the APG-66v3 (90km range). So we talk about over 120km vs 5m3 target.

https://airforcesmonthly.keypublishing. ... ight-test/

The AN/APG-83 can simultaneously perform search, tracking and lock-on functions. For multiple targets, the detection range is increased by more than 30% compared with the original APG-66(V)3 radar.

This is a significant step backwards from what I had. I had 215km v 5m^2 detection, 167km lock.


215 km should be for the APG-80. It has 100% more range then the APG-68. Which is 105 km against a 5 m2 Target.

BTW your range for the RBE2 AA seems pretty close. Range advantage is according to Thales clearly over 50% compere to the PESA version. (140km vs 3m2).
Last edited by swiss on 28 Jul 2019, 07:00, edited 1 time in total.
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Unread post27 Jul 2019, 23:12

Those numbers sound way off for the APG-83 (which is a more advanced set than the APG-80.)
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Unread post27 Jul 2019, 23:18

wrightwing wrote:Those numbers sound way off for the APG-83 (which is a more advanced set than the APG-80.)


The main reason seems to be the cooling system for the APG-83.

https://www.ainonline.com/aviation-news ... velopments

Specialists at other radar design houses question how effective the APG-83 can be since the set depends on using the airflow that cools the other avionics in the F-16 and then using an internal liquid-cooling module and heat exchanger that is on-board the radar set itself.

“This has the advantage of not having to plumb a liquid-cooling system into the aircraft, as Lockheed Martin did with the F-16E/F Block 60 for the UAE,” said a U.S. airborne radar firm’s representative. “But the question is whether or not that cooling solution allows you to run the radar’s T/R modules at their maximum capacity because of the heat that they generate. Plus there are other questions about whether the modules could be software limited in order to be in compliance with U.S. government policy” on the export of sensitive technology.

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Unread post29 Jul 2019, 04:50

sprstdlyscottsmn wrote:Oh man, this feels cathartic. Here is the full comparison for the F-15SA. I will be open to any comments or tweeks you all may want to see until this weekend. At that time I will consider the format and content "locked" and I will add the F-16V.

Dude, you are the man
I think you should add these charts for each missile if possible
Image
Or one chart with all missiles at the same altitude and start velocity
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Unread post29 Jul 2019, 22:28

sprstdlyscottsmn wrote:
southerncross wrote:A question that springs to mind before going deeper into the results is if it is sensible to use the Su-35S as a comparison.

That is why I was honest and upfront about the model validity. I have just as much data available to me about the Su-35 as I do about any other non-US plane.


OK I see, if there is not more info about other non-Western planes then Su-35S is indeed a good choice because

1. There are lots of data available from old Flanker manuals for a reasonably similar airframe
2. Information disclosed about the Su-35 should be reliable for export planes, the ones most likely to be confronted by US

swiss wrote:Empty weight of the Su-35 should be ca. 19 Tonnes.

Also according to Tass.

https://tass.com/defense/1069215

The Su-35S weighs 19 tonnes, has a service ceiling of 20,000 meters, can develop a maximum speed of 2,500 km/h and has a crew of one pilot. The fighter jet’s armament includes a 30mm aircraft gun, up to 8 tonnes of the weapon payload (missiles and bombs of various types) on 12 underwing hardpoints.


Could be reasonable but can hardly be trusted as the plane's ceiling is 18 km and max speed <2400 km/h. Tass can be trusted when they quote someone, when they do the filling to put the news in context you better don't rely on them.

MTOW is 34,5000 kg, with 11,300 kg fuel and 8,000 kg weapons. If all that could be carried simultaneously, it would mean an empty weight < 15,200 kg, which seems low. I would struggle to make an assumption of the plane's empty weight and think this is very much the reason Russia is not disclosing it officially, since of all crucial data for the analysis it is the one that can be kept hidden the best.

@Spurts:

I have some further comments, please excuse me if some are very basic, since this is the first time I see your analysis.

1. Do you have a list or annex with the basic technical specs of the planes used for the preparation of the analysis? It would help to check possible errors and understand assumptions

2. Weight of the F-15SA seems difficult to find, I have 17,010 kg which seems much lower than the one you use for your clean configuration. Maybe you use another better data or you take the F-15E weight without CFTs? My source is:

https://militaryedge.org/armaments/f-15sa/

Don't know how reliable it is but seems semi-official organization funded by the government?

3. Comparisons seem done based on a given % of the internal fuel. This is usual but places an unfair burden on the planes with higher fuel fraction. Wouldn't it be better to estimate the amount of fuel needed for an arbitrary range for each plane and then use it in the comparisons?

As a result of some of these assumptions, results of the clean vs clean scenario are very much skewed, since there is a huge 15,000 lb weight difference between the F-15SA and Su-35S, when they are similarly sized aircraft. Coherently, there is almost no difference between clean and air-to-air configurations for the Sukhoi, but very substantial for the F-15.

4. Maybe you already know this site, but if not it may be interesting for you to check whether there is useful information for your analysis. They do comparisons of planes in manoeuvring combat but from the Russian perspective:

http://www.aviapanorama.ru

Thanks
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Unread post30 Jul 2019, 14:15

I just want to be sure I understand what I'm seeing.

1. In the performance section 2.1, it says the table will display the following:
-Thrust to Weight ratio using installed engine thrust at 0.85M at 36,000ft
-Excess T/W ratio using installed engine thrust at 0.85M at 36,000ft

However in both Loaded flight configurations we see
T/W and (T-D)/W, There is no Excess T/W but I guess there shouldn't be specially at the altitude.

So If I'm not mistaken "T/W" represents the Thrust to Weight ratio of an installed engine at max AB at 0.85M / 36,000ft. It would be way too high if it was Excess T/W.

2. In both the level flight and the Turn performance graphs there are 2 lines each for Clean, Air, Ground and Max. Guessing the larger line in level flight represents Max AB while the inner line represents Mil.

In Turn performance the Outer line represents Inst Turn while the inner line is sustained?
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Unread post30 Jul 2019, 15:42

zero-one wrote:I just want to be sure I understand what I'm seeing.

1. In the performance section 2.1, it says the table will display the following:
-Thrust to Weight ratio using installed engine thrust at 0.85M at 36,000ft
-Excess T/W ratio using installed engine thrust at 0.85M at 36,000ft

However in both Loaded flight configurations we see
T/W and (T-D)/W, There is no Excess T/W but I guess there shouldn't be specially at the altitude.

So If I'm not mistaken "T/W" represents the Thrust to Weight ratio of an installed engine at max AB at 0.85M / 36,000ft. It would be way too high if it was Excess T/W.

2. In both the level flight and the Turn performance graphs there are 2 lines each for Clean, Air, Ground and Max. Guessing the larger line in level flight represents Max AB while the inner line represents Mil.

In Turn performance the Outer line represents Inst Turn while the inner line is sustained?

1. Thank you for pointing out something that is not clear to non-aero-engineers. Excess T/W ratio is the (T-D)/W figure. I have amended the description of the data. You are otherwise correct in your understanding.

2. You are 100% correct.
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Unread post30 Jul 2019, 16:55

Thanks Sprst.
I also noticed something in turn performance,

I believe the tip of the Inst. turn represents the 9G line correct? If so:

1. How come the Su-35's Inst. turn seems to Plateau at 20 deg/sec before hitting the 9G line while the F-15's Inst turn seems to keep shooting upward until it hits the 9G line.

2. Were the effects of TVC taken into account? I imagined TVC to cause abnormally high Inst turn rates in the extreme slow speed part of the envelope before doping back to more predictable levels as speed climbs. (pretty silly now that I think about it)

3. Just a follow up on TVC, I'm not sure if the Su-35's TVC is still manually controlled or part of the CLAWS ala F-22. Or maybe there is an override switch or something. If so, then that would cause abnormally high energy bleed rates
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Unread post30 Jul 2019, 17:08

Answers in-line in bold

zero-one wrote:Thanks Sprst.
I also noticed something in turn performance,

I believe the tip of the Inst. turn represents the 9G line correct? If so:

1. How come the Su-35's Inst. turn seems to Plateau at 20 deg/sec before hitting the 9G line while the F-15's Inst turn seems to keep shooting upward until it hits the 9G line.
resolution issue. That chart has .05M speed increments to save space.

2. Were the effects of TVC taken into account? I imagined TVC to cause abnormally high Inst turn rates in the extreme slow speed part of the envelope before doping back to more predictable levels as speed climbs. (pretty silly now that I think about it)
While TVC is not listed in those charts it is used in the applied turn performance for the two-circle missile fight

3. Just a follow up on TVC, I'm not sure if the Su-35's TVC is still manually controlled or part of the CLAWS ala F-22. Or maybe there is an override switch or something. If so, then that would cause abnormally high energy bleed rates
Oh, it does cause abnormally high bleed rates, even if it does keep the nose pointed where you want it
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Unread post30 Jul 2019, 20:04

swiss wrote:Empty weight of the Su-35 should be ca. 19 Tonnes.

Also according to Tass.

https://tass.com/defense/1069215
The Su-35S weighs 19 tonnes, has a service ceiling of 20,000 meters, can develop a maximum speed of 2,500 km/h and has a crew of one pilot. The fighter jet’s armament includes a 30mm aircraft gun, up to 8 tonnes of the weapon payload (missiles and bombs of various types) on 12 underwing hardpoints.

Could be a possible value, but can hardly be trusted as ceiling is 18 km and max speed is < 2,400 km/h. Tass can be trusted when quoting experts, but these fillings for their pieces are not official info and are often dead wrong.
MTOW is 34.5 t, internal fuel 11.3 t, payload 8 t. IF all can be carried simultaneously that would make empty weight < 15.2 t, which seems too low. I would struggle to make an assumption of empty weight for the plane, but maybe the official acceleration values allowed Spurts to make a good estimation.
sprstdlyscottsmn wrote:That is why I was honest and upfront about the model validity. I have just as much data available to me about the Su-35 as I do about any other non-US plane.


I see, then it makes sense to use Su-35 despite the uncertainty of some data:
- There are lots of concrete info about the Su-27, which is a reasonably similar airframe
- Export models, the ones for which info is available, are the ones US is more likely to meet in combat.

I have some other comments, please excuse if they are very basic but is the first time I see your analysis:

1. Do you have a list or annex of the basic plane data you are using for the analysis? It would help find errors and understand assumptions
2. Weight of the F-15SA seems difficult to find. I found 17.010 kg, seems clearly higher than what you are using for your clean model. Probably you are using F-15E empty weight without CFTs?
My source, it seems semi-official: https://militaryedge.org/armaments/f-15sa/
3. Using fuel load as a % of max internal fuel is found frequently but IMHO places an unfair burden on planes with higher fuel fraction. Wouldn't it be better to estimate the fuel needed for a given flight distance for every plane and use it for the analysis?
There is a massive 15,000 lb difference between F-15SA and Su-35S in your clean configuration, which is going to skew the results quite a bit I think.
4. Maybe you know this site already, these guys do some part of your analysis but from the Russian perspective. I though you might want to check them out to see whether their results are consistent with yours or they have useful info:
http://www.aviapanorama.ru
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Unread post31 Jul 2019, 15:55

You have some good questions for a first timer. I will answer in-line in bold.

southerncross wrote:...MTOW is 34.5 t, internal fuel 11.3 t, payload 8 t. IF all can be carried simultaneously ...
Almost no fighter aircraft can carry max payload at max fuel unless you are counting fuel as payload, such as EFTs. Max payload is often defined at the sum of the individual weight limits of the pylons.

I see, then it makes sense to use Su-35 despite the uncertainty of some data:
- There are lots of concrete info about the Su-27, which is a reasonably similar airframe
I do use an available Su-27 Flight Manual to determine the lift curve slope and a few other things

I have some other comments, please excuse if they are very basic but is the first time I see your analysis:

1. Do you have a list or annex of the basic plane data you are using for the analysis? It would help find errors and understand assumptions
Section 1, at the end of each aircrafts description, lists the source for my data i used to generate the models. I do not have, nor do I currently plan on having, a list in the analysis of the 50+ physical characteristics that go into the model.
I do see what you are saying though, and giving the more technically minded people the raw data could be beneficial.


2. Weight of the F-15SA seems difficult to find. I found 17.010 kg, seems clearly higher than what you are using for your clean model. Probably you are using F-15E empty weight without CFTs?
My source, it seems semi-official: https://militaryedge.org/armaments/f-15sa/
I am using the F-15E flight manual to get weight and fuel for the F-15SA, and as I stated in section 2.1 Clean means no CFTs. You are correct

3. Using fuel load as a % of max internal fuel is found frequently but IMHO places an unfair burden on planes with higher fuel fraction. Wouldn't it be better to estimate the fuel needed for a given flight distance for every plane and use it for the analysis?
My analysis is step by step. Talking about basic things that don't really apply like pure T/W and eventually evolving to "how far can you reach this type of target and how well does your ECM suite allow you to prosecute the target". Sections 2.1 and 2.2 do use the 60% initial fuel as a starting point but the effects are different than you think. In 2.2.1 Afterburner Time Remaining is a scored component. The ability to accelerate from .8M-2.5M in 2.5 seconds (obvious exaggeration) means nothing if you no longer have the fuel to fight. In fact, in all of section 2.4 each plane (focus and adversary) have to account for ground time, take-off, climb, cruise, combat, RTB, and reserves.

There is a massive 15,000 lb difference between F-15SA and Su-35S in your clean configuration, which is going to skew the results quite a bit I think.
Sure does. But no one fights clean. You can clearly see in 2.1.4 that once loaded, even with A-A munitions only, that the Su-35 has superior acceleration. There is a reason that noting in 2.1 is counted for a score, because it is mostly meaningless even though it is a group of specifications often used for comparison.

4. Maybe you know this site already, these guys do some part of your analysis but from the Russian perspective. I though you might want to check them out to see whether their results are consistent with yours or they have useful info:
http://www.aviapanorama.ru
I do not know that site. Looking at it I do not see an where such analysis exist. I am always on the lookout for useful info however. The breadth of information that gets shared here at F-16.net is where I have learned a great deal about fighter aircraft, especially from a systems perspective (I am an aerodynamics guy myself)
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