Hope you have a good read!
Headed and founded by Pavel Sukhoi, Sukhoi OKB-134 was one of the first pioneers of jet aviation following the end of the Second World War. They introduced a number of designs that could have been successful had it not been for Mikoyan’s higher success with the MiG-9, but much more importantly; the swept-wing MiG-15, which overshadowed the Su-9 (1946) and Su-11 (1947) (designs based on the Me 262, but more powerful).
The start for the OKB was terrible. Two designs were rejected in just one year, and the situation was made worse with the Su-15 (1949); a radar-equipped all weather interceptor prototype with two 37mm cannons. While it sounded fancy for that time, in reality it was a troubled aircraft in aspects of stability. Following its crash in 1949, the Su-17 (also the first use of this designation, not to be confused with the later fighter-bomber) and Su-10 medium-ranged jet bomber never had the chance to become airworthy as a result of Stalin’s harsh leadership which demanded the closure of Sukhoi’s design bureau.
After our beloved Joseph Stalin passed away in 1953, the bureau was revived and the Soviet air industry took a major new step. It was also moved to Factory No.1, therefore becoming known as OKB-1, before moving to Factory No.54 and becoming OKB-54.
In the 1950s, it was discovered that delta-winged designs utilising thin air foils provided a large increase in speed performance, however deteriorating said aircraft’s maneuverability at the same time. This was particularly an issue, as the Korean War was still taking place and it proved that old dogfights even with transonic jets were still a thing. Many heated debates between chief designers of OKBs and the Soviet Air Force’s leadership took place, and it was decided by Sukhoi that they would pursue the delta-winged design. During one of the debates, it was agreed upon by different chief designers with the Soviet Air Force that delta-winged aircraft would be designated with the suffix “T” (“treugolnoye krylo”) and the swept-winged designs would be designated with the suffix “S” (“strelovidnoye krylo”).
Hence, Sukhoi OKB would go on to develop two versions of their upcoming aircraft: one with delta wings, and the other with swept wings, and they would be designated T-1 and S-3 respectively (later, the T-3 was chosen). There was another project to develop a tactical fighter which received the in-house designation of S-1.
After the Soviet Council of Ministers submitted these directives, the Soviet Air Force their requirements for the designs: that they must be capable of 1,900 - 1,950 km/h at high altitude, capable of flying at 20,000 m and climbing to 15,000 m in two minutes, a range of 1,400 km and 2,250 km with and without drop tanks respectively at an altitude of 10,000 m and to be armed with two 30mm cannons (but this was to be dropped soon after).
In mid 1954, Sukhoi OKB prepared a full scale mockup of the swept-winged interceptor which was given the in-house designation of S-3. However, MAP deemed it impractical and so Sukhoi dropped the project in favor of the delta-winged concept for the interceptor project. The T-1 and T-3 passed the review stage in autumn and were cleared for prototype construction between October and November the same year.
At that point, the S-1 tactical fighter prototype was at a more advanced stage of development and would go on to be known as the famous Su-7 fighter (later fighter-bomber). To speed up development, the T-3 shared many similarities with the T-1.
All three were chosen to be powered by the Lyulka AL-7F afterburning turbojet with 7,500 kgf on normal power and 10,000 kgf on afterburner(s).
Now, you’re probably wondering how the T-1 and T-3 differ. Mainly, the T-1 was to be equipped with an SRD-3 Grad ranging radar; a reverse-engineered copy of the American AN/APG-30 of the F-86A, while the T-3 was equipped with the native twin-antenna Almaz-3 search and tracking radar, with a max detection and tracking range of 16 and 6 km respectively.
Morever, the T-1 had three 30mm cannons, while the T-3 had one, in each case 65 rounds per gun. Both could be equipped with ARS-57 FFAR rockets.
After a series of major design changes (such as switching from a monocoque fuselage design to a semi-monocoque design, etc), the T-3 was finally completed in 1956, after a new order that was issued almost two years prior (Dec. 1954) to shift the priority to arming the new aircraft with air-to-air missiles instead.
In 1955, MAP shifted its priorities which greatly favored the T-3 instead of the T-1, and the commonalities between the T-1 and T-3 proved vital to these priority changes. Since work on the T-1 was at a more advanced stage, and priorites shifted to the T-3’s design, it was decided that the T-1 should be converted to the T-3 and become the first flying prototype. The conversion involved replacing the fuselage nose up to the cockpit section, as well as the the forward bays of the wings.
As previously mentioned, priorities were shifted towards dedicated missile-armed interceptor designs, so the T-3 was to feature newly-designed K-6V and K-7L air-to-air missiles.
By the end of the year 1955, all static tests had been completed, and work on finishing the first prototype gained priority. All the components had been assembled except for the wings, and the result was 95% readiness. Some equipment intended for the prototype had encountered delays, such as the Almaz-3 radar, SRZO-2 IFF and the PVU-67 computing sight designed to work in conjunction with the K-6V and K-7L missiles, but this was no issue as it didn’t hinder the OKB from proceeding to the flight testing stages. Because it was to be armed with missiles, the cannons were dropped.
Sukhoi OKB completed the first prototype in March 1956 and finally, a prototype of the intended engine was cleared for installation the next month. On the 23rd of April, 1956, the prototype was trucked to Sukhoi’s flight testing facility and underweight ground checks. On the 26th, it made its maiden flight and on the 24th of June the same year, it had its public debut at Moscow-Tushino.
Flight tests had two stages: Stage A and Stage B.
Stage A lasted until the 28th of September, and was concerned with the T-3’s flight envelopes. 31 flights were made during this stage, 27 of which were test flights, and it was at this stage the prototype was equipped with K-7L missiles to determine its flight characteristics with their load. By October, the engine reached its service life and the plane was sent back to the OKB’s experimental shop for a replacement. It was in lay-up until March 1957 and apart from the engine change, it also received the intended Almaz-3 radar, SRZO-2 IFF and the PVU-67 computing sight. The original Mindahl communications radio replaced the RSIU-4 Doob and the parachute container was enlarged.
Stage B began on the 8th of March, 1957, and was considerably behind schedule since the replacement engine took some time to deliver. It was also in this stage between June and August 23rd that the missiles were verified and live launches were performed.
A total of 80 flights were made: 38 hours and 21 minutes, 18 months.
Still the engine was plagued with issues. Instead of reaching 7,500 kgf on normal power and 10,000 kgf on maximum, it reached 6,850 kgf and 8,950 kgf respectively, which affected its maximum speed, and due to teething issues it was prone to failures and so with experienced gained from the S-1 fighter-bomber (the Su-7’s prototype), the never-exceed speed was set to 1.83 Mach during the manufacturer’s test flights. The landing and takeoff distances were also higher than anticipated since the aircraft’s weight exceeded the intended figures (takeoff run was 1,050 - 1,150 m and landing run was 1,840 m without the brake chute). The radome arrangement also made it clear that it affected the aircraft’s maixmum speed.
Its avionics suite included an Almaz-3 radar, an SPO-2 Sirena-2 RWR, an SRZO-2 IFF, a PVU-67 computing sight, an ARK-5 ADF, a Mindal VHF communications radio, an MRP-48P marker beacon receiver, a GIK-1 compass and an AGI-1 fighter-type non-toppling artificial horizon.
The last modification of this prototype series was the Sukhoi T-5. This was a conversion from the first T-3 prototype with two Tumansky R-11F-300 afterburning turbojets, found on the MiG-21F and MiG-21F-13, to meet a new requirement. Because of the installation of those engines, the fuselage had to be heavily redesigned, and the designers opted for the nose intake of the T-43 (the prototypes of the production Su-9).
Due to the extent of the changes, the conversion took 8 months. Tests showed that it was overpowered, and despite the much higher drag, it could reach speeds faster than those of the T-3. However, the engines still had bugs to be eliminated at that time; they used to shut down on their own during zoom climbs, and these engines were hard on start up due to the air intake design of the aircraft.
Sukhoi continued to adapt the T-3’s prototype to carry the K-7L AAMs. In 1955 - 1956, the second prototype received a different designated by the calling of “PT-7” and was to be equipped with an improved Almaz-7 radar. This new radar required the aircraft’s nose design to be heavily changed as it had different dimensions and the plane became quite bizzare-looking.
Detailed design was finished in Dec 1955 and work on constructing the prototype soon commenced. The wing design was also altered, but these TsAGI recommendations proved protracted for the aircraft’s development. Also soon, the Lyulka AL-7F was replaced with the uprated AL-7F-1.
Its maiden flight ocurred at the end of June, 1957 and a total of 24 flights were made. The State Acceptance Trials tests for the T-3 proved to have an impossible schedule to keep, so a new deadline was issued. Sukhoi did the most it could to complete the K-7L’s tests with live launches before the aircraft was handed over to the military, but these plans were destroyed because the engine had to be replaced and it took longer than anticipated, which is why only six flights were made in that year. Work continued in 1958 with 18 flights by the end of June with only six live missile launches.
The T-3 was expected to enter production in its PT-7 configuration, MAP issued an order to produce three examples of the PT-7 at Factory No.153 in 1956 and delivering them to Sukhoi to accelerate the development and the State Acceptance Trials schedule.
The production example of the PT-7 was designated PT-8, and at that time the factory was producing the MiG-19S izdeliye 26, so since the PT-8 was next in line; it received the in-house and factory designation of PT-8 izdeliye 27.
However, as we know, the schedule proved to be too optimistic. The three were completed, but only one of them ever flew. In April 1958, the Council of Ministers updated the specifications and requirements for the aircraft.
Part of the reason why the Su-9 was being developed is that in the 1950s, the threat of Western strategic bombers skyrocketed to an alarming rate. At that time, the PVO was mostly armed with early MiG jets and Yak-25 interceptors, and what they all had in common was an unsatisfying service ceiling and lack of effective weapons to deal with the threat. In particular, only being armed with cannons.
Because of this, the Soviet government demanded the acceleration of the development of surface to air missiles and manned interceptors, and in an extremely brief period of time.
Once the better Lyulka AL-7F-1 turbojet became available, the Council of Ministers ordered Pavel Sukhoi himself on the 26th of August, 1956, to increase the service ceiling of his T-1 and T-3 prototypes (both were still underdeveloped at that time) to an astonishing 21,000 m. By the way, this increased demand in higher service ceilings admitted to all Soviet design bureaus is the reason why suddenly many Soviet aircraft in the 50s were equipped with rocket boosters. The production Su-9 would end up fitted with two U-19 rocket boosters.
To this end, they were fitted with the uprated AL-7F-1, and since it had a larger casing diameter some parts of the rear fuselage had to be redesigned. Furthermore, after the successful test flights of the T-3, the TsAGI recommended Sukhoi OKB to incorporate leading edge dogtooth slats. Finally, in order to reach the required top speed, the nose cone of the T-3 was replaced with a much more suitable one, in fact it was taken directly from the successful S-1 prototype (what would become the Su-7 later). This altered airframe was completed in December 1956 and was designated T-43. Because it was purely an experimental aircraft, it was not fitted with weapons, and as the rocket boosters’ development was behind schedule, it also flew without them on the 20th of October, 1957. And when it did, not only did it fulfill the promise, it managed to reach 21,500 m! Three days later, it excelled again and managed to reach a top speed of 2,200 km/h at 10,000 m (or mach 2.06). In later trials, it was retrofitted ESUV-1 electrohydraulic air intake control system to prevent engine surge and provided continuous control of the cone throughout flight, although from the get go it was designed with a system that controlled it automatically.
After the T-43-1 succeeded, Sukhoi went on with developing it further. They wanted to study means of how to install an Almaz radar inside the small shock cone of the T-43-1, and in a new larger shock cone (this one was developed into the T-47 prototype, which eventually led to the Su-11 later in this thread).
In the mid 1950s, NII-17 was the USSR’s only institute for airborne radar development. In 1957, the radars which were in service were the Izumrud RP-1 and RP-5, fitted to the MiG-17PF and MiG-19PM respectively, in addition to the RP-6 Sokol found on the Yak interceptors. The problem was, the Izumrud series of radars were quite inadequate for a supersonic interceptor designed around that mission, and the RP-6 was too big and bulky to fit inside that small shock cone too. The institute were remedying this by developing the Uragan and Pantera radars, but their development was painfully slow.
Out of nowhere, OKB-1, a division from MOP (the Ministry of Defense Industry) quietly developed a radar so compact to fit inside the small shock cone yet powerful enough to meet the desired specifications and optimized for use in conjunction with the RS-1U beam-riding air-to-air missile, the only AAM in service during that time in 1957. This fire and control radar was first designated TsD-30, and in October the same year, the RS-2US was developed and was also proven compatible with the TsD-30. The Council of Ministers also formulated new requirements for what would eventually become the Su-9; no longer was it meant to be an interceptor only, but also part of an aerial intercept weapons system comprising the aircraft and the Vozdukh-1 (Russian for “Air-1”) GCI (ground controlled intercept) system. As such, it was fitted with the Vozdukh-1 GCI.
The directive envisaged two derivatives: one with the TsD-30 radar and four RS-2US AAMs, and the other with the Oryol (Eagle) radar (later named RP-11 Oryol) and two K-8M AAMs. Also, all work on the K-6V and K-7L missiles was terminated. The weapon systems around these two were designated T-3-51 and T-8M.
Sukhoi allocated the T-43-1’s product code to the T-3-51, and in addition to the existing T-43 weapons system; five initial production T-3 prototypes were converted to this standard, totalling six prototypes, and they were also to be equipped with the new KS-2 ejection seats and the Lazour datalink system as part of the GCI. Two prototypes were converted in Moscow, and three in Novosibirsk to speed up the process. The ones in Moscow were designated T-43-2 and T-43-6, while the ones in Novosibirsk were designated T-43-3, T-43-4 and T-43-5.
Stage A and B of test flights were held for the T-3-51. After their conclusion, it was determined that the prototypes required the ESUV-1 system to control the shock cone and prevent engine surges, since at Mach 1.8 the engines used to throttle back. They were only retrofitted with the system once they were sure they needed it.
On the 20th of July, 1959, the T-43-6 prototype crashed after witnesses reported that it was disentegrating in mid air. A search and rescue operation was quickly scrambled after test pilot Kobischan stopped responding to the control tower, but the boggy ground proved it was impossible to extract the wreckage. A monument was later created for the pilot and his prototype jet. To make up for the loss, the air force transferred another production T-3 / T-8 to Sukhoi, and upon conversion it was designated T-43-11 and joining the State Acceptance Trials the next month.
The State Acceptance Trials came to an end, with 407 test flights in total, by the 9th of April 1960. Upon completion, the T-43-3, T-43-4, T-43-5 and T-43-8 served as testbeds for IR-homing missiles, mainly the K-13. Meanwhile, the T-43-7 and T-43-10 were used as testbeds for the new AP-28Zh-1 autopilot, the T-43-12 to test the aircraft with more range by integrating another internal fuel tank and allowing provisions for two more drop tanks, the T-43-15 to test the new TsD-30TP radar and the T-43-17 to test the new avionics fitted to the upcoming Su-11.
On the 15th of October, 1960, the Su-9 was finally born.
Soon after its production commenced, the TsD-30 radar was renamed to RP-9U, the K-5MS missiles received the designation RS-2US, the plane’s official name in service was designated Su-9 and the whole interception system was given the name Su-9-51.
The RP-9U provided a detection range of approximately up to 20 km against bomber-sized targets and 10 - 15 km against fighter-sized targets. The maximum tracking range was 10 km head-on and 5 - 7 km tail-on (rear aspect). This radar was well optimized for the RS-2US AAMs; the beam-riding missiles which were its principle armament at the start. They could be fired at targets maneuvering at up to 2G only however, and their maximum overload was 18G, but due to the limited effectiveness of its guidance method, it never reached 18 g factor. They were equipped with the PRD-45 rocket motor which used to burn for 3.5 - 7 seconds and were effective from 2 - 5 km against targets flying at a maximum of 1,600 km/h.
Four pylons were allocated under the wings to load up to four of these missiles, so long as it had the unbroken wing design, and as with every radar of its time, it was highly prone to ground clutter, thus attempting to use the AAMs at low altitude was difficult.
The Lyulka AL-7F-1 turbojet was a very powerful engine, with up to 6,240 kgf on normal power and 9,200 kgf on afterburner mode. Thanks to this engine, the Su-9 climbed like a rocket; measuring a figure of 200 m/s starting from low altitude. At high altitude, it was capable of 2,230 km/h at an altitude of 12,000 m, however at sea level it was actually only transonic; capable of 1,150 km/h only. Interesting fact is that after a certain prolonged period of time with the afterburner ignited, the top speed would be reduced to 2,120 km/h.
Later, it was retrofitted with the Lyulka AL-7F-100 uprated to 6,800 kgf (normal power) and 9,600 kgf (afterburner power), then the AL-7F-150 and AL-7F-200; the main changes being in service life (100, 150 and 200 hours respectively).
Due to the wing design and the weight of 11,440 kg, it had pretty long takeoff and landing distances; 1,200 m and 1,150 - 1,250 m respectively (without the brake chute). Speaking of the wing design, the plane could withstand up to 7G of maneuvering.
Touching back on the avionics, it had the SPO-2 Sirena-2 RWR for self defense (but it was an old RWR, with only rear-aspect capabilities), a GIK-1 compass, an RSP-6 instrument landing system with an ARK-5 Amur ADF (automatic direction finder), an MRP-56P beacon receiver, a PVD-5 pitot, an AP-28Zh-1B autopilot an SOD-57M distance measurer, an RSIU-4V two-way VHF radio, a Lazour ARL-S datalink, a Vozdukh-1 GCI, an AKS-5 gun camera, a PAU-547 photo module recorder in the radar, a KUSI-2500 airspeed indicator, an AGI-1 artificial horizon, a VDI-30 altimeter, an EUP-53 turn and bank indicator, an AM-10 g load indicator, a VAR-300 vertical speed indicator, a UKL-1 heading indicator, a Mach indicator, an ARK-5 ADF indicator, an AChKh clock and an SRZO-2M IFF system. Later, all Su-9s were retrofitted with the SARPP-12 flight data recorder.
Since it was a dedicated missile-armed interceptor, it had no internal gun(s). However, in the late 1960s and early 70s, two production Su-9s were fitted with a UPK-23-250 gunpod housing a 23mm GSh-23 autocannon with 250 rounds for testing, flown by three different pilots who fired at La-17 drones and ground targets. Moreover, between 1966 and 1967, a couple of Su-9s were actually tested with the CAS role when they were fitted with 250 kg FAB-250 bombs!
Despite the efforts, they were deemed nearly pointless. The Su-9 was designed as an interceptor dedicated to that role in the IA PVO and thus didn’t need the secondary CAS role, while the gunpod addition proved a very good asset, installing it meant that the Su-9 had to sacrifice a drop tank pylon which was vital to it since without external stores it lacked the intended range. For this reason, the UPK-23-250 gunpod did manage to see usage, but it was limited.
The wings also had leading edge dogtooth, which automatically deployed at medium to high speeds to improve flight stability and maneuverability, despite the CofM directives. However, later they proved to be problematic, and the design was reverted back to the unbroken wing, which made way for two more missile pylons. With the leading edge dogtooth wing, the Su-9 could only carry two AAMs. The inboard pylons used the APU-19 launchers/adapters, while the outboard pylons (when present) used the APU-20s.
With nearly 1,000 examples built, the Su-9 was the backbone of the IA PVO until the late 70s and 80s when the MiG-23P began replacing it. There were seven Su-9 regiments deployed.
Game Equivalents: F-104A/C/G, MiG-19, J35A (suggested BR: 9.7)
Pros:
- Very fast at high altitude (2,230 km/h)
- High acceleration
- Rocket-fast climb rate of 200 m/s
- Four missile pylons
- Leading edge dogtooth
- Decent radar for the BR it would be at
- Has RWR and IFF
- Good maneuverability
- Can be equipped with a gunpod with a 23mm GSh-23 with 250 rounds
Cons:
- Transonic at sea level (1,150 km/h)
- No heat-seeking air-to-air missiles
- Terrible AAMs for the most part; beam-riders are only useful against big targets and in head-ons
- Radar heavily prone to ground clutter
- Delta-wing design which causes high speed loss in turns
- Average range without drop tanks; fuel consumption high on afterburner
- No internal gun(s)
- Limited CAS if any at all
- Lack of any form of countermeasures
- The RWR was old; only rear-aspect
- Average 7G wing limit
- Two missile pylons only when the leading edge dogtooth was in place
While technically not an entirely different aircraft, I think it deserves its own place.
As you may have read in the T-43 chapter, there were several prototypes which were used as testbeds for IR-homing missiles, namely the K-13s. However, they fell out of favor when it was decided to convert the RS-2US AAMs into heat-seeking missiles.
When testing of the new R-55 air-to-air missiles began in 1967, concluded and then entered service in 1969, the Su-9 was immediately retrofitted with them. In order to make the radar compatible with the new missiles, the RP-9U was modified into the RP-9UK.
The R-55 missiles increased the aircraft’s lethality; tests showed that the R-55 was almost twice more effective than the R-3S, even though it was advised to fire it at targets pulling just 3G. It retained the G limit of the RS-2US, but became much more maneuverable thanks to the redesigned control surfaces and the TGS-59 IR-seeker. It was more or less like a slightly worse Soviet Red Top.
With this addition, the main mission loadout became 2 x RS-2US on the inboard pylons with APU-19 launchers and 2 x R-55 on the outboard pylons with APU-19D and APU-20D launchers, but it could also be loaded with four R-55s instead.
Other changes also ocurred, mainly to the avionics. For example, the AGI-1 artificial horizon system was replaced with the AGD-1, the GIK-1 compass was replaced by a UKL-1 heading indicator and the KS-2 (actually, the earliest aircraft had the KS-1 too), an RV-8UM low range radio altimeter was added and the ejection seat was replaced by the KS-2A. Lastly, the APU-19 and APU-20 inboard & outboard pylons/adapters/launchers were replaced with the modernized APU-19D and APU-20D (for the RS-2US). These new launchers had the OR-4 umbilical connectors instead of the earlier OSh-56 for the missiles, and had the electronic distribution box was removed.
Unfortunately, the dogtooth leading edge was eliminated on later production aircraft (see Su-9 Early chapter).
Game Equivalents: F-4C, F-104A/C/G, MiG-19, J35A, F-8C/E, Lightning (suggested BR: 10.0)
Pros:
- Very fast at high altitude (2,230 km/h)
- High acceleration
- Rocket-fast climb rate of 200 m/s
- Four missile pylons
- Decent radar for the BR it would be at
- Has RWR and IFF
- Good maneuverability
- Can be equipped with a gunpod with a 23mm GSh-23 with 250 rounds
- New R-55 AAMs with off boresight capability and twice the effectiveness of the R-3S (Soviet counterpart to the Red Top)
Cons:
- Transonic at sea level (1,150 km/h)
- Terrible RS-2US beam-riding missiles
- Radar heavily prone to ground clutter
- Delta-wing design which causes high speed loss in turns
- Average range without drop tanks; fuel consumption high on afterburner
- No internal gun(s)
- Limited CAS if any at all
- Lack of any form of countermeasures
- Removed leading edge dogtooth
- The RWR was old; only rear-aspect
- Average 7G wing limit
As mentioned before, the directive envisaged two types of aircraft: one fitted with the RP-9U radar compatible with the RS-2US air-to-air missiles, and the other fitted with the Oryol (“Eagle”) radar and K-8M air-to-air missiles. While the T-43 prototypes were being worked on, more aircraft that bore the designation “T-47” were also underway with the latter specified equipment.
On the T-47, they managed to reach a compromise with the developers of the Oryol radar and keep decent aerodynamic control for the aircraft in addition to radar performance by placing both antennas inside a large conical centerbody within a new air intake design; the forward fuselage diameter was significantly increased and two large dielectric panels were incorporated on the sides of the nose.
The intake aerodynamics deteriorated the performance of the design by a bit, but this was considered an acceptable trade-off since the USSR badly needed means of countering high-flying threats from the West. At this stage, they were still deciding on the T-47’s future armament, and they were still considering a mix of internal cannons and air-to-air missiles.
On the 18th of December, 1957, GKAT and the Soviet Air Force issued a demand together to the Novosibirsk No.153 factory to manufacturer an initial batch of ten T-47 prototypes. They were to be armed with Almaz radars (specifically which were yet to be decided) in a movable shock cane and two 30mm NR-30 cannons. Interestingly, at this stage they actually did not consider AAMs just yet.
Before the joint order was issued, MAP also iordered in August of that same year that the first T-47 prototype should be constructed. The second production PT-8 prototype was also delivered to Sukhoi OKB-51’s construction shop in Moscow to be converted. After the appropriate changes, two 30mm NR-30 cannons were installed in the wing roots, as well as the Almaz radar and two ORO-57 rocketpods for 57mm ARS-57 FFARs. Later when the month of December came, it was delivered to their flight testing facility. On the 6th of January, 1958, the T-47-1 performed its maiden flight, but its flight tests had to be suspended soon after it finished 15 test flights because the PT8-4 prototype was being worked on, and the AL-7F-1 engine was in short supply back then, so they just removed it from the T-47-1 and installed it on the PT8-4.
On the 4th of June, 1958, the Council of Ministers ordered all work on the T-47-1 along with the idea of installing NR-30 cannons and the K-7L AAM program to be stopped. As a result, the PT8-4 was also dropped.
Sukhoi were interested in the RP-6 Sokol radar, which proved to be compatible with the upcoming K-8M air-to-air missiles with much better range in comparison to the RS-2US, developed in both IR-homing and SARH models, and because it only had a single antenna. When Yakovlev OKB-115 ran into problems concering the development process of the Yak-27K interceptor, the Ministry of Aircraft Industry (MAP) proposed that Sukhoi adapts the Yak-27K’s radar and missile armament into their Sukhoi T-3. Detail design of this idea commenced in mid-1958, and all the aircraft that were made available by the termination of the K-7L missile system program such as the PT-7, PT8-4 and several low rate initial production (LRIP) examples of the T-47 were to be converted to the new standard (LRIP T-47s were originally T-3 prototypes in small pre-production numbers). In total, there were six aircraft at this point.
The T-47-2 was the first to enter test flying. Since it was purely intended for aerodynamical tests, it was unmodified and no radar was fitted. Unfortunately, it crashed soon afterwards, but the pilot survived.
Next in line was the T-47-3. This was the PT-7 we talked about way earlier, but entirely converted to the T-47 standard at this point. It was also the first in the T-3-8M program (referring to the T-3 prototype program armed with K-8M missiles). Its air intake shock cone was all-metal, not dielectric because the intended radar was still not available. Not only was it used for missile testing though (apparently the IR version of the K-8 was also used!) but also for aerodynamic testing. It was trucked on the 26th of November, 1958, and began its flight testing the next month.
In addition, because this series of prototypes were to lead to the Su-11 with a different shock cone to accomodate the different radar, a new ESUV-2 intake control system was developed in place of the older ESUV-1 mentioned before.
Two more LRIP T-47 examples - T-3 prototypes in other words - were also converted. The T-47-4 and T-47-5 were armed with the Oryol radar from the get go, and were specifically used to test the IR-homing variant of the K-8M. The other unarmed prototypes were retrofitted with the Oryol radar in January 1960. In August 1959, all were flown to Vladimirovka airbase to commence manufacturer testing, mostly to test the SARH variant of the same missile and to test the radar against real targets. 40 flights were made for this cause.
On the 18th of September, 1959, the T-3-8M aerial intercept weapons system was officially submitted for State Acceptance Trials. Stage A lasted from November 1959 till April 1960, and involved the T-47-3, T-47-4 and T-47-5 performing live launches of the IR-homing model of the K-8M. By the time this stage ended, the T-47-7 and T-47-8 prototypes were finished and designated to test the SARH version of the K-8M. It’s worthy of noting though, that the T-47-8 had the uprated AL-7F-2 engine instead, delivering 10,100 kgf on full afterburner, and an additional internal tank for more fuel.
On the 26th of April, 1960, Stage B concluded, which was the stage they used to debug the Oryol radar. Additionally, the shock cone design was adapted to the ESUV-2 system.
By mid-1960, all prototypes were upgraded to match the T-47-8 standard.
The trials were reached to an end in May 1961, with 475 flights and over 700 if we include the manufacturer’s test flights also.
On the 5th of February, 1962, the T-3-8M weapons system was officially inducted into the Soviet Air Force’s inventory. With it entering service, the plane bore the official service name of Su-11, the Oryol radar was designated “RP-11 Oryol” to match the type and the K-8M missiles entered service as the R-8MT infrared-homing model and the R-8MR semi-active radar-homing version.
Compared to the RS-2US and R-55 AAMs, the new missiles were a lot more potent in range. The R-8MT’s TGS-14 seeker head could lock onto afterburning targets from 20 km and engage targets at high altitude from ranges reaching up to 10 km. However, it was only rear aspect. The R-8MR with the PARG-14 on the other hand had the same range, but was all-aspect. Both models had a maneuvering limit reaching 14G in the air, and pilots were advised not to fire them while maneuvering beyond 3G however. They were powered by PRD-141 rocket motors with a whopping 11,200 kgf of thrust that lasted for 2.5 to 6 seconds. However, the pylon count was reduced from 4 to 2.
The typical mission loadout for the Su-11 was one R-8MR and one R-8MT. Provisions were also made for a UPK-23-250 gunpod housing a GSh-23L with 250 rounds.
The next year in 1963, the better R-98 was developed and came in two variants: the R-98T IR-homing model, and the R-98R SARH-guided version. They retained the same maneuverability as their predecessors, however their reliability and nose immunity to countermeasures, as well as increasing their power supply, were further improved. The changes applied were promising; the IR version actually became limited all-aspect; the first limited aspect missile in the world (entered service a year before the Red Top!) featuring the new TGS-14T seeker-head, while the SARH version received the more reliable PARG-14-VV. The autopilot and fuse were also improved, and the rear-fairing was reshaped to become perfectly cylindrical instead of the tapered design. When they were inducted into service with the Su-15, the Su-11 also received them. Their maximum kill ranges were 8 - 18 km head-on and 2 - 14 km in pursuit.
Since the radar of the Su-11 differed from the Su-9’s, it did not come with RS-2US missiles nor R-55s.
Regarding the avionics, while the RP-11 Oryol was not a pulse-doppler radar, it had average to good immunity to ground clutter. In head-on situations, against a bomber-sized target, it had a detection range of 30 - 35 km, and 25 - 30 km against a fighter-sized target. While in tail-on engagements, it detected bomber-sized targets at 15 - 18 km and fighter-sized targets at 10 - 15 km. The tracking range measured between 8 - 20 km, depending on the altitude, aspect and the engaged target’s size.
The rest of the avionics suite was almost entirely shared by the Su-9. Of course, it had the SRZO-2M IFF and SPO-2 Sirena-2 RWR, among everything else but with a few exceptions: the UKL-1 direction finder was replaced with the UKL-2, the ESUV-1 shock cone controller’s place was taken by the ESUV-2, the KS-1, KS-2 and KS-2A ejection seat systems replaced with the KS-3, the ARK-5 ADF with the ARK-10, the AGI-1 artificial horizon system with the AGD-1,an RSIU-5 VHF instead of the RSIU-4 and more new systems were added: the D-3K-1-110 three channel yaw/pitch/roll damper and a KI-13 compass.
Because the Su-11 had the more powerful Lyulka AL-7F-2 with 6,800 kgf norm. and 9,600 kgf on afterburner, it beat the Su-9’s 2,230 km/h top speed by 110 km/h: at 12,000 m it was capable of flying at 2,340 km/h. However, it had the same top speed at sea level and the same climb rate. It was a more effective interceptor due to its performance & increased fuel capacity, updated avionics and weapons.
Despite being successful for its time, the Su-11 only had 108 examples built, mainly because OKB-51 was looking forward to the new T-58D prototype (which became the Su-15 later). It served almost three regiments.
Game Equivalents: F-4C, F-104A/C/G, T-2, Lightning, MiG-19 (suggested BR: 10.0)
Pros:
- Extremely quick at high altitude; 2,340 km/h and an improvement over the Su-9’s top speed of 2,230 km/h
- High acceleration
- Rocket-fast climb rate of 200 m/s
- New and effective R-8MR/T air-to-air missiles with good range
- Retrofitted with the R-98R and R-98T with improved effective range, immunity to countermeasures and reliability
- The R-98T was limited/all-aspect
- Good radar with high and effective range for the BR it would be at
- Has RWR and IFF
- Good maneuverability
- Can be equipped with a gunpod with a 23mm GSh-23 with 250 rounds
Cons:
- Transonic at sea level (1,150 km/h)
- Radar prone to ground clutter albeit less than the RP-9U and RP-9UK
- Delta-wing design which causes high speed loss in turns
- Average range without drop tanks; fuel consumption high on afterburner
- No internal gun(s)
- No CAS whatsoever; never tested
- Lack of any form of countermeasures
- Heavier than the Su-9
- Average 7G wing limit
- Old rear-aspect only RWR
- Four pylons reduced to two
