Sukhoi Su-15 Flagon - History, Design, Performance & Dissection

[SrNowel59917 656]

On 15/11/2021 at 12:20, csla1972 said:

Yes, it's experimental, but it never bothered Gaijin. So theoretically it is possible that we will see a modification of 4x R-60.  Either way, the Su-15TM as well as other aircraft from the Sukhoi line are much needed.

There shouldn't be a problem since we have f4 f and f104 s with aim 9j

[d1saster 0]

@EpicBlitzkrieg87 Do you have information about the maximum G-limit of the R-98MT?

Edited July 12, 2022 by d1saster

[EpicBlitzkrieg87 8,345]

7 hours ago, d1saster said:

@EpicBlitzkrieg87 Do you have information about the maximum G-limit of the R-98MT?

 

Yes. 14G total maneuverability and 3G on launch. That information and more is in the section of the first production variant. 

Edited July 12, 2022 by EpicBlitzkrieg87

[SickSix 300]

Oh, surprised I have never seen this before. Love it! +1

[d1saster 0]

10 hours ago, EpicBlitzkrieg87 said:

 

Да. Общая маневренность 14G и 3G при запуске. Эта информация и многое другое находится в разделе первого серийного варианта. 

No you have information for the R-98 but not for the R-98M rocket.

On 9/22/2021 at 1:38 AM, EpicBlitzkrieg87 said:

Moreover, much like the R-8MR and R-8MT, both the R-98R and R-98T were capable of pulling 14G, and their pylon and target G limits were 3G. Their tracking rate was 12°/s. 

 

On 9/22/2021 at 1:38 AM, EpicBlitzkrieg87 said:

With the new radar also came the improved R-98MR/T air-to-air missiles. These had improved kill ranges; 5 - 24 km head-on and 2 - 15 km in pursuit; improved over the previous kill ranges of 8 - 18 km head-on and 2 - 14 km for the R-98R and R-98T respectively. They were loaded under updated PU-2-8 racks

 

Edited July 13, 2022 by d1saster

[EpicBlitzkrieg87 8,345]

7 hours ago, d1saster said:

No you have information for the R-98 but not for the R-98M rocket.

On 22/09/2021 at 01:38, EpicBlitzkrieg87 said:

 

 

I already told you 14G, because they have the same maneuverability. If it were not so I would tell you plainly as I'm critical in these matters. The biggest change that ocurred is making them compatible with the RP-26 Taifoon radar of the Su-15TM, but no increase in seeker or rudder sensitivity to improve maneuverability. 

 

From Sukhoi Interceptors: The Su-9, Su-11, and Su-15: Unsung Soviet Cold War Heroes

 

Spoiler

Kindle version and hard copy

 

 

 

 

Edited July 13, 2022 by EpicBlitzkrieg87

[d1saster 0]

1 hour ago, EpicBlitzkrieg87 said:

 

 

Я уже говорил вам 14G, потому что маневренность у них одинаковая. Если бы это было не так, я бы сказал вам прямо, поскольку я критичен в этих вопросах. Самое большое изменение, которое произошло, заключается в том, чтобы сделать их совместимыми с РЛС РП-26 Тайфун Су-15ТМ, но без увеличения чувствительности ГСН или руля направления для улучшения маневренности. 

 

От перехватчиков Сухого: Су-9, Су-11 и Су-15: незамеченные советские герои холодной войны

 

Reveal hidden contents

Версия для Kindle и печатная копия

 

 

 

 

Thank you! But in your image, the R60 has an overload of 42G(in game - 30G), which is very strange. If it is true that the R-98M is limited to 14G, then this will seriously reduce their effectiveness in the game.

[EpicBlitzkrieg87 8,345]

2 hours ago, d1saster said:

Thank you! But in your image, the R60 has an overload of 42G(in game - 30G), which is very strange. If it is true that the R-98M is limited to 14G, then this will seriously reduce their effectiveness in the game.

 

These are the maximum G limits of their airframes, in other words it's impossible for the R-98 to pull more than 14G or it would break apart. The same goes for the R-60; in real life if it managed to pull more than 42G, it would break mid-air, but luckily for the missile it was never that fast at tracking to reach its physical limit. Its tracking speed kept it at 30G. Hope I'm clear!

 

Because the R-98 tracked at approx 12°/s and had a low launch limit of 500 m there is a good chance it did indeed reach its physical limit but without overloading the frame past that. 

 

If I refer back to the Su-15TM technical operations manual I could probably find something on the missiles if you want. 

Edited July 13, 2022 by EpicBlitzkrieg87

[Danzig [email protected] 479]

I am all for more interceptor and just lesser appreciated aircraft like this however balancing them is kinda a weird one imo especially since they are honestly a year or so late 


The only ones i can really see coming to the game are the Su-15TM and BiS at this point and tbh I am also abit on the fence on whether they should get R-60Ms since that would mean they would get put at a BR where they are just kinda there and do not much else but suffer....
 

[El [email protected] 789]

2 hours ago, Danzig [email protected] said:

I am all for more interceptor and just lesser appreciated aircraft like this however balancing them is kinda a weird one imo especially since they are honestly a year or so late 


The only ones i can really see coming to the game are the Su-15TM and BiS at this point and tbh I am also abit on the fence on whether they should get R-60Ms since that would mean they would get put at a BR where they are just kinda there and do not much else but suffer....
 

Not everything that gets added needs to be top tier. Lotsa 1950's/60's interceptors still need to be added.
Alternatively, the Su-15 would make for a decent tier 7 premium when tier 8 is introduced. Good air to air potential but plenty of weaknesses alongside some ground pound potential. A combo Gaijin loves in their premiums. 

[EpicBlitzkrieg87 8,345]

7 hours ago, El [email protected] said:

Not everything that gets added needs to be top tier. Lotsa 1950's/60's interceptors still need to be added.
alternatively, the Su-15 would make for a decent tier 7 premium when tier 8 is introduced. Good air to air potential but plenty of weaknesses alongside some ground pound potential. A combo Gaijin loves in their premiums. 

 

I don't agree with this. R-60Ms and R-98MR/Ts is a decent combination for a 10.7 jet or so. I think they should add it to start the Sukhoi fighter/interceptor line before the Su-27 gets added.

 

9 hours ago, Danzig [email protected] said:

The only ones i can really see coming to the game are the Su-15TM and BiS at this point and tbh I am also abit on the fence on whether they should get R-60Ms since that would mean they would get put at a BR where they are just kinda there and do not much else but suffer....

 

I don't mind it because the trade-off is that it doesn't get countermeasures unless the guns are traded. 

Edited July 19, 2022 by EpicBlitzkrieg87

[El [email protected] 789]

11 hours ago, EpicBlitzkrieg87 said:

 

I don't agree with this. R-60Ms and R-98MR/Ts is a decent combination for a 10.7 jet or so. I think they should add it to start the Sukhoi fighter/interceptor line before the Su-27 gets added.

 

That is why I figured it would make for a good tier 7 premium. Soon 10.7 won't be top tier anymore and I don't expect this to be added before tier 8 is added. I was thinking ahead a bit as that makes more sense then expecting it right now.

[Danzig [email protected] 479]

This is a bit of a weird question, but would i be incorrect in saying that R-98s are just soviet redtops? because at a glance that is what they seem most similar to, just with more range and the option for radar guidance.

[EpicBlitzkrieg87 8,345]

12 hours ago, El [email protected] said:

That is why I figured it would make for a good tier 7 premium. Soon 10.7 won't be top tier anymore and I don't expect this to be added before tier 8 is added. I was thinking ahead a bit as that makes more sense then expecting it right now.

 

The Su-15bis would be an interesting premium or event vehicle, but in my opinion the Su-15TM should be in the tech tree like I explained. Or maybe vice versa because the Su-15bis is better, but it's a prototype so I don't know. 

 

I really think we should see a line for Sukhoi fighters (Su-9 early or late --> Su-11 --> Su-15TM) before the Su-27 gets added.

4 hours ago, Danzig [email protected] said:

This is a bit of a weird question, but would i be incorrect in saying that R-98s are just soviet redtops? because at a glance that is what they seem most similar to, just with more range and the option for radar guidance.

 

The R-98T and R-98MT are limited all aspect like the Red Top in real life and have nearly the same G tolerance, I can see a rough comparison. 

[El [email protected] 789]

11 hours ago, EpicBlitzkrieg87 said:

 

The Su-15bis would be an interesting premium or event vehicle, but in my opinion the Su-15TM should be in the tech tree like I explained. Or maybe vice versa because the Su-15bis is better, but it's a prototype so I don't know. 

 

I really think we should see a line for Sukhoi fighters (Su-9 early or late --> Su-11 --> Su-15TM) before the Su-27 gets added.

Definitely. Which version doesn't really matter to me as long as they find their way in game. Definitely need the Su-9 and Su-11 too. Would actually love to see the Su-9 most with K-5 and K-55 missiles.

[Danzig [email protected] 479]

10 hours ago, El [email protected] said:

Definitely. Which version doesn't really matter to me as long as they find their way in game. Definitely need the Su-9 and Su-11 too. Would actually love to see the Su-9 most with K-5 and K-55 missiles.

Those would be interesting to see yeah, as well as the rest of the YaK-28 series such as the 28P, PM and 28-64.

[El [email protected] 789]

12 hours ago, Danzig [email protected] said:

Those would be interesting to see yeah, as well as the rest of the YaK-28 series such as the 28P, PM and 28-64.

Definitely. You and I are on the same page.

[EpicBlitzkrieg87 8,345]

On 21/07/2022 at 04:19, El [email protected] said:

Definitely. Which version doesn't really matter to me as long as they find their way in game. Definitely need the Su-9 and Su-11 too. Would actually love to see the Su-9 most with K-5 and K-55 missiles.

 

I prefer the Su-15TM as the tech tree variant, although it would be unfair because the Su-15bis would be better and not the tech tree one (as it was a prototype), and I think the R-55 missiles would be really cool on the Su-9

 

On 21/07/2022 at 14:43, Danzig [email protected] said:

Those would be interesting to see yeah, as well as the rest of the YaK-28 series such as the 28P, PM and 28-64.

 

As long as it's the Yak-28P (1966), need those extra two missiles. 

[Danzig [email protected] 479]

21 hours ago, EpicBlitzkrieg87 said:

 

 

As long as it's the Yak-28P (1966), need those extra two missiles. 

Ideally yes, what were the missiles anyways? just R-8s and R-3s

Spoiler

http://www.airwar.ru/image/idop/fighter/yak28-64/yak28-64-2.jpg

And a bit of an odd one but do you know what the Missiles on the outer pylons of the 28-64 are?

 

Edited July 23, 2022 by Danzig [email protected]

[EpicBlitzkrieg87 8,345]

30 minutes ago, Danzig [email protected] said:

Ideally yes, what were the missiles anyways? just R-8s and R-3s

Hide contents

http://www.airwar.ru/image/idop/fighter/yak28-64/yak28-64-2.jpg

And a bit of an odd one but do you know what the Missiles on the outer pylons of the 28-64 are?

 

 

R-8MR/T (R-8MR1/T1 also) and (from 1966 onwards) R-3S only. 

 

That's a very good question, those missiles are mostly unknown to even many well known Soviet authors. Judging by the year of the Yak-28-64's design and their nose, I think they're K-7S missiles. Or that they actually tried the R-55 on it! It seems like it but my discernment skills here are dead Otherwise I'm as clueless as you are. 

 

The ones in the inner pylons are definitely dummy R-98Rs.

 

Here's another view

 

 

In time I'll make a thread on the entire Yak twinjet family.

Edited July 23, 2022 by EpicBlitzkrieg87

[TR_GEN_TARIK_E 140]

On 22/09/2021 at 01:38, EpicBlitzkrieg87 said:

The Su-9 and Su-15 were the backbone of the IA PVO until the 80s when the MiG-23P, MiG-25P/PD/PDS and variants of the MiG-31 began replacing them. Before replacing them, they were the main capable interceptors of the Soviets, designed to replace the twin-engined Yakovlev jets (Yak-25/27/28) and the MiG-19PM. Despite the efforts, the Yak-28 showed more promise as an interceptor since it had more reliable engines and better range than the Su-9. The Su-11's production run was actually cut in favor of the Yak-28. 

 

The Su-15 came to remedy the issues of the Su-9 and Su-11, and it really did. After several projects such as the Sukhoi P-1, T-37 heavy fighter, T-49 etc, what would become the Su-15's prototype was favored.

 

This is a continuation of the previous topic:

 

 

Origins

 

(T-37 heavy interceptor, a promising project to replace the Su-9 and Su-11 which was unexpectedly canceled)

 

 

As everyone knows, the 1950s was a very troubled climate for the Soviet Union, since the West had began fielding new airborne-strike systems and long-ranged strategic bombers. The PVO was comprised mainly of MiG-17A/F and Yak-25 jets at that time (later the Yak-27 and MiG-19PM). Such jets weren't capable of intercepting strategic bombers with inadequate performance and cannons only. This is why jets such as the Yakovlev Yak-28, Sukhoi Su-9 and Su-11 were developed: high-speed, missile-armed aircraft were needed to counter the threat. 

 

However, there was an issue... Nikita Khrushchev was the head of state at that time, and he had little respect for the military aviation. During his era, 35 aircraft projects were terminated, and 21 engine programs alone in 1958 - 1959. He had a soft spot for SAM systems instead to defend the country, and when it came to desgining new aircraft, only conversions or upgrades of existing aircraft were allowed. Khrushchev's "missilisation" of the Soviet Union had a big blow on the Soviet aircraft industry that took six years to recover. 

 

Despite this climate, favor was still found in OKB-51 (Sukhoi OKB), since the Su-7 tactical fighter had been put into production and then converted to a fighter-bomber under the designation of Su-7B, while the Su-9 had just completed its acceptance trials, entering production henceforth, and the Su-11's trials had begun. 

 

Now, there was an issue with the Su-7 and Su-9. A very BIG issue. The Lyulka AL-7F and its derivatives suffered from reliability issues, mainly the AL-7F-1. In the first 1 year and a half of the Su-7's service entry, 20+ Su-7 and Su-9 examples crashed. More than half of the accidents were attributed to random engine failures, and the time between overhauls was just 25 to 50 hours. The engine was very expensive to produce, thus was available in short numbers. Moreover, the very promising and nearly complete  T-37 heavy interceptor  with the more reliable and powerful Tumansky R-15-300 and forming the T-3-9A interception system was very unexpectedly canceled alongside the K-9 missiles, a sad end to what was going to be a remarkable aircraft. It was obvious in 1961 that the situation was not good. 

 

Sukhoi faced yet another setback in the early 1960s: the PVO began leaning towards the new Yak-28P twin-engined interceptor, as it showed more engine reliability and safer flying. To this end, MAP (the Soviet Ministry of Aircraft Industry) demanded that the Su-11's production be cut short in heavy favor of the Yak-28P and the new Tu-128. Even more, the promising MiG-21PF from MiG began its trials. This was a blow to the Su-11, and only 108 examples were produced in total. Now Sukhoi was facing the possibility of being closed altogether again. 

 

Considering Khrushchev's attitude towards the military aviation at the time, chances of developing all-new manned combat aircraft were close to zero, and all Sukhoi could do was modernize existing designs, with hopes of them being accepted only if state-of-the-art missile systems were incorporated. (Fun fact, this is why the Su-24 was actually at first a delta-winged interceptor with a 150 - 170 km-capable radar with different proposed missile designs! When Khrushchev was ousted and replaced by Brezhnev who favored the military aviation, it was no longer disguised as an aircraft derived from the Su-15 prototype family under the designation T-58M and then became its own thing; Sukhoi finally freely explored the tactical bomber role)

 

This is exactly the situation which led to the start of the Su-15. At that time, they weren't quite aware of it yet though. They started developing a new single-engined interceptor at their own risk under the in-house designation of "T-58". To win the support of the higher ups and avoid possible negative consequences, it was disguised as a further upgrade of the existing T-3-8M weapons system, the system which was formed by the Su-11 (see the previous thread). It was to be armed with a radar offering longer range than the RP-11 Oryol of the Su-11, and missiles with lethality increased in the kill probability and range department. OKB-339 offered the Oryol-2, a further upgrade of the RP-11, and an all-new Vikhr (Whirlwhind), a scaled down version of the Tu-128's Smerch. However, both of them were too bulky to fit inside the axisymmetrical air intake of the Su-11 so the only option was to use the entire nose section aft of the cockpit for the radar and to use lateral air intakes, which OKB-51 had gained experience in from the P-1 and T-49 experimental projects. 

 

Still, the T-58's air intake design ended up differently, featuring two-dimensional with vertical airflow control ramps, found on the F-4 Phantom and F-106 Delta Dagger. But in the Soviet Union, this design was not yet fully explored. It should also be noted that the sector-shaped isoenthropic air intakes found on the T-49 had a staunch support at TsAGI; Prof. Gersch Grodzovski, who once visited Pavel Sukhoi urging him to use such intakes on his T-58 project forming the seemingly upcoming T-3-8M3 weapons interception system, but he refused as it seemed risky. He then instructed his designers only to change the fuselage structure as far as the section after the cockpit, to ensure maximum commonalities with the Su-9 and Su-11, and minimizing production costs, to ensure the same No.153 factory would keep on producing his jets. 

 

Development was rapid, and as early as July 1960 the first piece of metal on the T-58's prototype was placed, and its forward fuselage assembly began. The project was still a private venture at that time, not being officially sanctioned by the government. 

 

However at this time the appetite of the military started growing. They demanded that the new aircraft has all-aspect engagement capabilities against targets flying at up to 27,000 m (!) and speeds up to 2,500 km/h. To appease the missile-minded leaders of the USSR at that time, they informed them that the upcoming design will only feature two air-to-air missiles. In November the same year, the Council of Ministers issued an order to equip the new jet with the Vikhr-P radar and the Polyot GCI system. The missiles were going to be 2 x K-40 air-to-air missiles in SARH and IR versions (what would later become the R-40R and R-40T of the MiG-25). In this configuration, the designation T-3-8M3 was used as the in-house designation and allocated as part of the Su-15-40 aerial weapons interception system. This is when the designation "Su-15" was used for the first time. 

 

Time passed, but the promising K-40 missile was nowhere near to be sighted, neither the CofM's anticipation of the project with the Vikhr-P radar. Hence, they continued the aircraft's development with the Oryol-2 radar and K-8M2 missiles; upgraded R-8MR and R-8MT missiles (which did not find success, however the K-8M2 was developed into the K-8M1P which came in IR and SARH, what became the R-98T and R-98T later). In the project's documents, this config was called the Su-11M, while the aerial intercept weapons system was allocated the designation "T-3-8M2". 

 

The T-58 was due for completion in September 1961, but work on it was canceled during that year's summer. Apparently, it was the specific related divisions within the government thought that hope was lost in an AAM-equipped fighter. Sukhoi struck back and proved them wrong. 

 

 

(T-58 blueprint from one of the ADP documents)

 

Sukhoi T-58D - Pavel's Retaliation

 

(T-58D-1 prototype, the first prototype of the Su-15, under final assembly)

 

 

As previously mentioned, the AL-7F-1 was a very troublesome engine. It's why the Su-9 and Su-11 had a negative reputation at first, before they had the AL-7F-1 replaced with the AL-7F-100, -150 and -250 later on. 

 

As an insurance policy, Sukhoi decided in late 1960 to prepare a new project derived from the T-58, characterized by the installation of two Tumansky R-21F-300 axial-flow afterburning turbojets in the side-by-side fuselage configuration. This was an advanced engine type rated at 7,200 kgf on full power (afterburner). 

 

The new project was designated T-58D  ("D" could stand for either "dvigateli" ("two engines") or "dorabotani" ("updated"), it is still unsure which is correct), but was still to be equipped with the Vikhr-P radar, Polyot GCI and K-40 air-to-air missiles, and officially known as the Su-15 at this point. This indicates how differently the Su-15 could have turned out had the missiles been developed in time! Though, the PVO was still adamant about the radar and missiles, despite MAP indicating that with the Oryol-2 and K-8M2s it would enter service much sooner. 

 

However, the R-21F-300's serious design flaws were eventually discovered. It was then decided to replace it with the R-11F2-300, found on the MiG-21F/F-13. OKB-51 already had experience with these engines in the twin configuration since they had meddled with them on the Sukhoi T-5 (see chapter 2 in the Su-9 and Su-11 thread). In any case, the twin-engine configuration significantly increased reliability over the single-engine design as originally planned for the older T-58. 

 

To speed up the development process, they decided to borrow the tail and wings of the Su-11. However, with all the new changes, it proved to be a lot heavier than the production Su-11. To redeem this, the designers resorted to installing blown flaps. 

 

The T-58D was enivisioned to become an interceptor that would have to deal with single, unmaneuverable targets flying between 20,000 - 24,000 m and speeds up to 2,500 km/h. Because it also seemed that it would stand no chance in engaging targets in pursuit mode since it didn't offer speed advantages due to the weight increase, they devised head-on tactics. The minimum missile launch range was limited to certain altitudes because the radar lacked LD/SD. 

 

To maximize the efficiency of the weapons system, they included an automatic flight control system (AFCS) with an AP-28T-1 autopilot with heading adjustment command modules and pre-programmed optimum climb profiles. 

 

The in-house reviews of the ADP and review commission were deemed unnecessary since at that time the T-58D was still considered to be no more than an upgraded Su-11. 

 

Wind tunnel tests were of course still held, as well as ground rigs were built to test the T-58D's electric hydraulic systems. After the AFCS was fully developed, it was designated SAU-58, and was actually tested on the seventh prototype of the Su-11 (T-47-7). 

 

(Here, the T-58D can be seen taking shape at MMZ No.51; Sukhoi's experimental shop at Moscow-Khodynka)

 

Sukhoi T-58D-1 / T-58D-2 / T-58D-3 - Tests Execution

 

(T-58D-1, the first prototype of the Su-15, properly coded "58-1" and seen with R-98R & R-98T missiles)

 

 

In early 1962, the first prototype, designated T-58D-1, was rolled out of the factory. As an aerodynamic testbed, it lacked the intended radar and test equipment occupied the radar's place of installation. It was mainly intended to test stability/handling and performance to test top speed, acceleration, range, service ceiling and fuel consumption rates, with and without drop tanks. 

 

It was trucked to the LII testing airfield and on the 30th of May, 1962, after R. Yarmakov checked and passed the T-58D-1's ground system checks and taxying tests, it performed its maiden flight under the hands of Vladimir S. Ilyushin, a Sukhoi OKB test pilot and the son of no other than Sergei Ilyushin, the aeronautics engineer and founder of Ilyushin OKB. He praised the aircraft for its flying for the most part, except that it had poor directional stability in comparison with the Su-11, an issue that was fixed by installing a 400mm "plug" at the base of the fin. 

 

By the end of the year, the prototype had completed 56 test flights under the manufacturer's test program and its "58-1" code was changed to "31 Blue". It displayed good performance and handling, meeting the expectations for the most part. 

 

Suddenly, even during these early stages, MAP issued an order to fit the aircraft with the Smerch-AS radar and to arm the prototype with K-8M2 air-to-air missiles. This decision was going to lead to the outcome of installing the same radar to the three advanced interceptors at that time: the Ye-155P (MiG-25P prototype), the Tu-128 and the T-58D. 

 

Despite the order, it was clear that the forward fuselage design would have to be radically changed, and since there was no prototype radar available for fitting, Pavel Sukhoi and Matus R. Bisnovat (head of Bisnovat OKB, designer of the RS-2US, R-8 and R-98 missiles) worked together to prove their point to MAP and the Commanders in Chief for the VVS and PVO and were successful in doing so; to install the upgraded Oryol radar instead, at least only initially. On the 13th of March, 1963, Dimitri F. Ustinov, CofM Vice-Chairmain wrote back in agreement to Pavel O. Sukhoi but also highlighting that the Smerch-AS would have to be used later. The military also agreed to reduce the size of their demands, stating that it would be fine if the requirements were changed to a maximum interception altitude of 23,000 m for targets at speeds up to 2,000 km/h instead. 

 

The initial stages of the State Acceptance Trials were to be held with the upgraded Oryol radar, and were to finish in November 1963. 

 

Since the first prototype was merely an aerodynamic testbed, the second and third prototypes (T-58D-2 and T-58D-3) were tasked with radar testing. There was a "Sobol" radar in development but it was canceled, so once again they resorted back to the original option, now designated Oryol-D ("D" against standing for "dorabotani" which is Russian for "modified"). At this stage, the brake chute was also relocated from the rear fuselage to the base of the rudder, and the KT104 nosewheel was replaced with the larger KT-61/3, while the main KT-69/4 landing gears were replaced with the identically-sized KT-117s but with more effective braking. In early 1963, the T-58D-1 underwent modifications to match the same standards as the T-58D-2 and T-58D-3. 

 

Until the end of 1963, Vladimir S. Ilyushin alongside two other test pilots kept on performing test flights, reaching 104 in the modified T-58D-1. 

 

Because it took them too long to decide which radar model should be used for testing, the T-58D-2 / second prototype did not begin its test program until April 1963. On the 4th of May the same year, it performed its maiden flight under the hands of Ilyushin again. The second prototype differed from the first by having a longer and more pointed nose radome with a cone angle of 28 degrees but the vertical tail was still unmodified and the brake chute was accordingly located ventrally. However, it featured a complete avionics fit, with the Oryol-D58 (izdeliye 303D) radar installed. 

 

 

(Not only the only rare photograph of the T-58D-2 in flight, but also colorized!)

 

As part of the manufacturer's test program, tests of the avionics suite lasted till June, and in August the second prototype was submitted for the State Acceptance Trials. The trials began on the 5th of August, and since the SAU-58 AFCS was running late in development, it was decided that another and separate trials schedule would be considered. 

 

To speed up the process, instead of the State Acceptance Trials incorporating two stages as usual (Stage A and B), it was decided to join them both together as one stage instead. 

 

The T-58D-3 (the third prototype) had its maiden flight on the 2nd of October, 1963. It differed from the previous two in the new AP-46 autopilot and a higher internal fuel capacity by 180 liters. 

 

The Air Force pilots were generally pleased with the T-58D-3, however they criticized it for the following:

 

1. Decreased aileron authority at low speeds
2. The engines ran roughly during certain vigorous movements with sideslipping
3. High takeoff and landing speeds
4. Deteriorated acceleration compared to the Su-11
5. 1.5 tons heavier than the Su-11 (10,060 kg vs 8,560 kg)
6. Instability during landing between 340 - 450 km/h

 

 

(T-58D-3)

 

Anyhow, on the 8th and 11th of October respectively, the second and third prototypes were flown to the GK NII VVS facility at Vladimirovka AB to continue the trials; more specifically to perform live missile launches against real targets. For starters, the radar's performance was tested against real targets such as Tu-16 and IL-28 bomber, Yak-25RV recon aircraft and a special Su-9L development aircraft (L.02-10) with an angle reflector to decrease the RCS. 

 

The State Acceptance Trials in general lasted from August 1963 till June 1964. They did not involve just the aircraft, but also the entire aerial weapons system built around it; designated Su-15-98, it comprised the Su-15 of course, the R-11F2-300 turbojets, the Oryol-D58 search and tracking radar and modernized K-8M1P air-to-air missiles which came in IR and SARH versions respectively; entering service as the R-98T and R-98R. Of course, the Vozdukh-1M GCI was also incorporated. The first K-8M1P / K-98 missiles were delivered in early 1964, and live missile launches were conducted. They met all expectations, except the inability to guarantee kills against high speed targets since at that time the fuse could not detonate the warhead in time at closing high speeds. The verdict was that in a head-on situation, the missiles were able to score kills against targets flying up to 1,200 km/h. 

 

The trials of the Su-15-98 system were so smooth, that the PVO expressed almost no criticism regarding it. A total of 87 flights had been made during the trials; 53 accepted "for the record", 13 training flights, 16 flights "off the record" and five tests for positioning and checkout. All of the aircraft's systems and equipment had been fully explored, meeting the requirements of the higher ups and the manufacturer's estimates. All three prototypes in total, under the trials, completed over 300 flights without malfunctioning, demonstrating the reliability of the aircraft design. It was quite well-made, to the point it received the acknowledgement of Air Marshall Savitskiy; a highly experienced WW2 pilot with strict standards. 

 

However, its range fell quite short in comparison to the intended estimate; 1,260 km instead of 2,100 km. In order to solve this issue, OKB-51 decided to eliminate the waist of the area-ruled fuselage to increase fuel capacity. The new modifications were tested on the T-58D-1, proving to be viable changes and were thus highly recommended; the internal fuel capacity had been upgraded to 6,860 liters, more than the original capacity with drop tanks(!). Also, to improve stability and handling, the aileron travel was increased from 15 degrees to 18x30 and the air intake ramp adjustment time was reduced from 12 to 5 - 6 seconds. On the 2nd of June 1964, till the 16th, the modified T-58D-1 underwent a special tests program and the T-58D-3 soon followed with the changes. The trials were officially completed on the 25th of June, 1964, after the last test flight was made by Savitskiy in the T-58D-2 on the 19th. 

 

The final report of the State Acceptance Trials (which referred to the weapons system as the Su-11-8M - stage one upgrade) indicated that the new aircraft offered significant advantages over the Su-11, especially in head-on engagement capabilities. It was recommended that the third prototype be the standard production version. And thus, the Su-15 was born. 

 

 

(The second production Su-15, "67 Blue", during trials)

 

 

In early 1965, the first prototype was explored with a new cranked delta design with increased area and longer span to improve handling and stability. These changes were incorporated to the late Su-15TM. Moreover, the first prototype was also used to test short take-off and landing (STOL), much like the MiG-21PD and MiG-23PD. It was designated T-58VD .

 

 

(T-58D-3, obviously the third prototype from the longer and more pointed nose radome and the taller vertical tail with an SPO-2 RWR)

 

Sukhoi Su-15 Early izdeliye 37 - The Saving Grace Inducted

 

(One of the first Su-15s produced, production code (c/n 031506), armed with one R-98R and one R-98T)

 

 

In 1966, the Su-15's production officially began. The first pre-production example was rolled out of the factory on the 21st of February, 1966 and was code-named "34 Red". With the Su-15 finally in production, Sukhoi was finally relieved. The trials were quite successful that any possibiltiy of the OKB facing entire closure a second time no longer seemed realistic. 

 

With the Su-15 in production, the new radar was redesignated to RP-15 Oryol-D58 and the missiles bore the new designations of R-98T and R-98R (IR and SARH respectively). Actually, they came improved compared to how they were during the prototype stages; they received the PRD-143 rocket motor with a thrust of 13,400 kgf and a burn time of 2.5 - 6 seconds, an improvement over the previous PRD-141 found on the R-8s. They were Mach 2-capable missiles with a kill range of 2 - 14 km in pursuit and 8 - 18 km head-on (this head-on range was achieved only by the SARH version, the IR version on the other hand did have all-aspect capabilities still). The R-98T received a new TGS-14T seeker head with liquid nitrogen cooling and all-aspect engagement (limited), similar to the Red Top and the late R-60M. The plane came equipped with two pylons with PU-1-8 launch rails, and usually had one IR and one SARH loaded.

 

Moreover, much like the R-8MR and R-8MT, both the R-98R and R-98T were capable of pulling 14G, and their pylon and target G limits were 3G. Their tracking rate was 12°/s. 

 

The RP-15 Oryol-D58 was a capable, non-LD/SD radar, with a detection range of 15 - 35 km at low and high altitude respectively, and a tracking range of 10 km at low altitude and 30 km at high altitude. Detection and tracking of targets were also influenced by the size of the engaged aircraft, scanning at an azimuth of +-60° and elevations of +31°/-15°. 

 

The rest of the avionics suite is listed as the following: RSIU-5 two-way VHF, MRP-56P marker beacon receiver, RV-UM low-range radio altimeter, ARK-10 ADF, SOD-57M distance measuring equipment, Lazour datalink, SRZO-2M IFF transponder, SPO-2 Sirena-2 radar-warning-receiver (RWR), KSI-5 compass system and an AGD-1 artificial horizon.

 

 

(The first ever production Su-15, coded "34 Red", before pre-production examples were delivered)

 

 

With the more reliable R-11FS-300s becoming available, the Su-15 was re-engined with those. No changes ocurred to thrust, only reliability was improved. The top speed of the Su-15 was 2,230 km/h at 11,000 m, and an unfortunate 1,100 km/h IAS at sea level. The climb rate remained more or less the same as the Su-11: 190 - 200 m/s. The maximum Mach speed was Mach 2.1. 

 

This early production model was purely delta-winged, unlike the later Su-15 sans suffix examples that were produced with cranked / double delta wings starting in 1968. Speaking of which, their limit was just 6G. 

 

No cannon armament was included. A later production example was used as a cannon testbed; the military kept demanding that the Su-15 should have at least one cannon. Sukhoi originally wanted the GP-9 gunpod, and ten aircraft from Batch 12 had the appropriate fittings, but none were actually equipped with them. By then, requirements were changed, and the UPK-23-250 gunpod was chosen with 250 rounds instead of 200. 

 

 

Game Equivalents: Su-7B, J35A, F-100 (suggested BR: 9.0 - 9.3)

 

 

Pros:

 

• Fast at high altitude (2,230 km/h) with a limit of Mach 2.1
• Good radar with decent range (15 - 35 km detection, 10 - 30 km tracking)
• Equipped with RWR
• Rocket-fast climb rate (190 - 200 m/s)
• Effective R-98R and R-98T air-to-air missiles with 2 - 14 km of range from the rear and 8 - 18 km from the front
• All-aspect heat-seekers (R-98T)

 

Cons:

 

• Two missile pylons only
• No cannon(s) installed whatsoever
• Old, rear-aspect-only RWR
• Lack of dogfight missiles to remedy the cannon-less issue
• Non-LD/SD radar, reliable starting from 2,100 m 
• Transonic at sea level (1,100 km/h IAS)
• Not capable of CAS
• BVR missiles with low maneuverability
• Low 6G wing limit

 

 

("01 Red", the first pre-production Su-15)

 

Sukhoi Su-15 Late izdeliye 37 - Recommended Changes

 

 

 

In 1968, it was recommended to incorporate the double delta wing design onto later production Su-15 examples. Moreover, gunpods were tested and officially inducted into service in 1971. The usual loadout became two R-98R/T air-to-air missiles and 2 x 23mm GSh-23 housed in two UPK-23-250 gunpods with 500 rounds in total. 

 

Despite the recommendation to produce the Su-15 with double delta wings, they were still produced with the older pure delta design for the time being. In 1969, from c/n 1115301 onwards, blown flaps were introduced to the pure delta wing design. The first Su-15 to be completed with double delta wings was c/n 1115331. 

 

Moreover, from c/n 1115336 onwards, all late Su-15s could be re-engined with the Tumansky R-13-300s with 4,100 kgf on normal power and 6,600 kgf afterburner, and from batch 11 all Su-15s had the SARPP-12V-1 flight data recorder. The new engines, while being more reliable, lowered the aircraft's ceiling by 400 m. Because of this, they were not widely used. In addition, a production Su-15 c/n 0615327 was tested with R-60 AAMs, and after testing was completed all late Su-15 sans suffix production models were retrofitted with them. The APP-50 chaff/flare dispenser with 50mm PPI-50 and PPR-50 flare and chaff cartridges was also tested, but it took the place of the gunpods. 

 

To summarize, late Su-15s usually came with two gunpods, two R-98R/T air-to-air missiles, two R-60s, blown flaps and with either pure delta or cranked delta wings. The cranked delta design had a wing limit of 6.5G. 

 

Production of the Su-15 late lasted from 1968 - 1971, and the production of the Su-15 sans suffix all in all lasted from February 1966 till 1971. It was succeeded by the more advanced Su-15TM. 

 

 

Game Equivalents: F-4C, F-100, MiG-19, F-104A/C/G, J35A, Su-7B/BKL (suggested BR: 10.3)

 

Pros:

 

• Fast at high altitude (2,230 km/h) with a limit of Mach 2.1
• Good radar with decent range (15 - 35 km detection, 10 - 30 km tracking)
• Equipped with RWR
• Rocket-fast climb rate (190 - 200 m/s)
• Effective R-98R and R-98T air-to-air missiles with 2 - 14 km of range from the rear and 8 - 18 km from the front
• All-aspect heat-seekers (R-98T)
• Gunpods inducted: two 23mm GSh-23 with 500 rounds
• R-60s introduced
• Countermeasures available
• Missile count increased from 2 to 4
• Improved 6.5G wing limit with cranked wing design

 

Cons:

 

• No internal cannons; gunpods increase drag
• Old, rear-aspect-only RWR
• Non-LD/SD radar, reliable starting from 2,100 m 
• Transonic at sea level (1,100 km/h IAS)
• Only two R-60s
• No CAS loadouts
• Countermeasures pod took the place of cannons
• High energy loss in turns with pure delta design
• BVR missiles with low maneuverability
• Low 6G wing limit with pure delta wing design
• 6.5G wing limit with cranked design still underwhelming

 

 

(Late Su-15 production model with two UPK-23-250 gunpods, one R-98R and one R-98T missiles, note the pure delta wing design)

 

Sukhoi Su-15T izdeliye 37M / izdeliye 38 - Huge Upgrade Program

 

 

 

Because the performance of the Su-15 did not fully satisfy the military, it was due for a mid-life upgrade. As a matter of fact, the reason why the Su-15 turned out the way it was is attributed to Sukhoi OKB being overloaded with work, as they were working on many projects at that time and the Su-15's prototype did not receive the most attention. It was supposed to be a lot more capable from the start, had it not been to the design bureau being overloaded with other projects at the time.

 

In mid-1966, several months after the Su-15 entered production, they envisioned it with a Korshun-58 radar, the SAU-58 was finally ready and the RSBN-5S Iskra short-range navigation system had just been developed at that time.

 

However, the new radar could not provide the intended performance, so all attention was directed towards the Smerch-A of the Ye-155P (the MiG-25P's prototype) and the project was canceled. Because of this, they decided to arm the Su-15 with the RP-26 Taifoon; a derived radar from the Smerch-A. 

 

The TP-26 Taifoon was a more capable radar than the RP-15 Oryol-D58, with a detection range of up to 70 - 75 km against bombers at high altitude and up to 60 km against fighters, 15 km and 10 km respectively at low altitudes. Tracking range was 50 - 55 km against bombers and 40 - 45 km against fighters, 10 km at low altitude for both sizes, scanning with +-70° azimuth and +30°/-10° elevation. 

 

Moreover, the new R-832M communications radio replaced the older R-802V, the Pion-GT antenna feeder system was introduced, the RBNS-5S Iskra short-range navigation system was inducted alongside an upgraded Lazour-SM datalink, a new SPO-10 Sirena-3 RWR and the long-awaited SAU-58.

 

The military also demanded that it receives CAS loadouts to make them useful for the Soviet Air Force's tactical arm; to this end the Su-15T could be loaded with 1 - 2 500 kg bombs, or four 100 or 250 kg bombs, up to two UB-16-157U rocketpods each with 16 x 57mm S-5K unguided rockets or two S-24 heavy unguided rockets. They actually also considered an internal cannon, and it happened, but remained only a prototype configuration. 

 

The new and formerly tested R-13-300 engines also made their way. As they were more powerful than the previous R-11FS-300s, the top speed at sea level was increased from 1,100 to 1,300 km/h at sea level, and the climb rate from 190 - 200 m/s to 228 m/s. 

 

Despite the enhancements, the Su-15T had only 20 examples produced, mainly because of issues which protracted its development and deliveries. The Su-15TM replaced it in October 1971 in production (but did not see service till 1975). 

 

 

Game Equivalents: F-4C, F-100, MiG-19, MiG-21F-13, F-104A/C/G, J35A (suggested BR: 10.3)

 

 

Pros:

 

• Fast at high altitude (2,230 km/h) with a limit of Mach 2.1
• Vastly improved radar
• Top speed at sea level increased from 1,100 to 1,300 km/h 
• Upgraded SPO-10 Sirena-3 RWR with more aspects
• Climb rate improved from 190 - 200 m/s to 228 m/s
• Has 2 x 23mm UPK-23-250 gunpods
• Equipped with R-60s and R-98R/Ts
• Countermeasures available
• CAS loadouts became available

 

Cons:

 

• No internal cannons; gunpods increase drag
• New radar, but not capable of LD/SD
• Only two R-60s at once
• No CAS loadouts
• Four missile count poor in comparison to other aircraft
• No countermeasures
• BVR missiles with low maneuverability
• Improved wing limit from 6G to 6.5G, but still low

 

 

 

Sukhoi Su-15TM izdeliye 37M - Finest Modernization

 

 

 

The best and final version of the Su-15, the Su-15TM. With more than 400 produced, this is the most definitive and lethal variant. 

 

Following the comprehensive Stage A and B of the State Acceptance Trials, the Su-15TM with the new radar was introduced to service, and the upgraded aerial intercept weapons system was designated "Su-15-98M". The new radar was the RP-26M Taifoon(-M); while it had to be designed with an ogival radome which negatively affected its range because conical design of the previous RP-26 proved troublesome, it was more reliable and was capable of +-70° in azimuth and elevations of +30°/-10°.

 

Range data as follows:

 

Detection range at high altitude: 65 - 70 km (bomber-sized targets), 45 - 55 km (fighter-sized targets)
Tracking range at high altitude: 40 - 45 km (bomber-sized targets), 35 - 40km (fighter-sized targets)
Detection range at low altitudes: 15 km (bomber-sized targets) 10 - 15 km (fighter-sized targets)
Tracking range at low altitudes: 10 km (bomber-sized targets), 5 -10 km (fighter-sized targets)

 

With the new radar also came the improved R-98MR/T air-to-air missiles. These had improved kill ranges; 5 - 24 km head-on and 2 - 15 km in pursuit; improved over the previous kill ranges of 8 - 18 km head-on and 2 - 14 km for the R-98R and R-98T respectively. They were loaded under updated PU-2-8 racks. 

 

 

(Su-15TM firing an R-98MR missile)

 

The SAU-58 AFCS was replaced with the modernized SAU-58-2, and the number of R-60s was increased from 2 to 4, as an Su-15TM example was tested with the APU-60-2 launcher (though it did not enter service with the Su-15 in general). In the 80s, it was retrofitted with improved R-60M AAMs. It also retained the possibility of loading the APP-50 chaff/flare dispenser, which unfortunately had to take the place of the aircraft's gunpods when it was to be fitted. 

 

Much like the previous Su-15T, it had basic CAS loadouts ranging from 100, 250 and 500 kg bombs, in addition to 32 S-5K unguided rockets or two S-24s. The fuel capacity was also improved. 

 

The Su-15TM stayed in service till the 90s until it was finally retired from service. It's infamous for the shooting of the Korean airliner. 

 

 

Game Equivalents: MiG-21MF, MiG-21SMT, J35D, F-104J/S, F-4C

 

 

Pros:

 

• Fast at high altitude (2,230 km/h) with a limit of Mach 2.16
• Vastly improved radar
• Fast at sea level; 1,300 km/h
• Equipped with SPO-10 Sirena-3 RWR
• Very good climb rate of 228 m/s
• Has 2 x 23mm UPK-23-250 gunpods
• New R-98MR/T missiles with higher kill ranges
• All-aspect heat-seeking AAMs (R-98T + R-98MT)
• Access to the APU-60-2 launcher providing up to four R-60 air-to-air missiles
• R-60M retrofitted
• Countermeasures available
• CAS loadouts retained
• Higher range than the previous models (1,380 km vs 1,260 km)

 

Cons:

 

• No internal cannons; gunpods increase drag
• New radar, but not capable of LD/SD
• New radar with higher reliability but worse range in comparison to the Su-15T's RP-26
• BVR missiles with low maneuverability
• Inferior to F-4 Phantoms, Mirages and other Western aircraft in speed at sea level
• Outmaneuvered by aircraft such as the MiG-21 and Mirage
• Underwhelming 6.5G wing limit

 

 

 

Sukhoi Su-15bis - Lost High-speed Potential

 

 

(The Su-15bis' sole prototype, a conversion from the fifth production Su-15TM "25 Blue", c/n 0306)

 

 

In the early 70s, a new powerful engine was developed: the Gavrilov / Tumansky R-25-300 with a second stage afterburner (or a contingency rating/power boost). Shortly after the Su-15TM's Stage A of the SAT (State Acceptance Trials) came to an end on the 25th of February, 1971, the CofM (Council of Ministers) issued a directive followed by a joint ruling from MAP and the Air Force to re-engine the Su-15TM with the latest R-25-300s. 

 

These new changes offered a thrust of up to 4,100 kgf on normal power, 6,850 kgf on afterburner and 7,100 kgf on full boost. An Su-15TM coded "25 Blue" (with the production code c/n 0306) was used as the prototype of what became known in-house as the T-58bis (and Su-15bis as the official service designation). The conversion was completed in the first half of the year at the Novosibirsk No.153 factory (which is the one that mainly produced early Sukhoi jets such as the Su-7, Su-9 and Su-11) and the prototype made its maiden flight on the 3rd of July, 1971.

 

Flight tests continued until the 20th of December the same year and they've proven that the Su-15bis had impressive and obvious acceleration improvements over the Su-15TM and a higher top speed, especially at low and medium altitudes with the contingency rating the engines provided. With the second stage afterburner, the Flagon could now intercept targets flying up to 1,000 km/h at 4,000 m in pursuit mode. 

 

Unfortunately, despite recommendation for production, it never received the status of a production aircraft. Instead, the Su-15TM remained the top variant, and the R-25-300 powered the MiG-21bis. 

 

 

Game Equivalents: MiG-21MF, MiG-21SMT, J35D, F-104J/S, F-4C

 

 

Pros:

 

• Top speed, acceleration and climb rate vastly improved in comparison with the Su-15TM, thanks to the R-25-300 engines (the same engine type as the MiG-21bis')
• Decent, high-ranged radar
• Equipped with SPO-10 Sirena-3 RWR
• Has 2 x 23mm UPK-23-250 gunpods
• Access to the APU-60-2 launcher providing up to four R-60 air-to-air missiles
• R-60M available
• CAS loadouts retained
• Effective (range-wise) R-98MR/T missiles
• All-aspect heat-seekers (R-98T and R-98MT) 

 

Cons:

 

• No internal cannons; gunpods increase drag
• New radar, but not capable of LD/SD
• New radar with higher reliability but worse range in comparison to the Su-15T's RP-26
• BVR missiles with low maneuverability
• Inferior to F-4 Phantoms, Mirages and other Western aircraft in speed at sea level
• Outmaneuvered by aircraft such as the MiG-21 and Mirage
• Underwhelming 6.5G wing limit
• Flight range reduced especially on second stage afterburner

 

 

(Another view of the same Su-15bis prototype)

 

Some variants are not included as they were trainers, such as the Su-15UT and Su-15UM, and testbeds with internal cannons, engine testbeds, avionics testbeds etc. 

 

Thanks for reading, I hope you liked this one. If needed, and I may do it on my own later, the post will get updated with even more information. 

 

 

 

 

Sources:

 

Soviet/Russian Aircraft Weapons Since WWII

Sukhoi Su-15 - Boeing Killer

Sukhoi Interceptors: Sukhoi Su-9, Su-11, Su-15 Vol. 16

Sukhoi Interceptors: Sukhoi Su-9, Su-11 and Su-15: Unsung Soviet Cold War Heroes

+1 bro