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Sturgeon's House

J35 Appreciation Station


LostCosmonaut
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I was very confused as to why you were toasting the engines of the F-84 and F-89 until I looked at the pictures.

 

SAAB builds quite sound airframes, but they're hamstrung by the engines.  The DB unit in the J-21 was reliable and well-designed, but just too damn weak by the time the thing took to the air.  The jet conversion used a first-generation jet turbine, and all first-generation jet turbines were ass.  I'm assuming similar applies to the lansen.

 

The engine in the draken was too big, the engine in the viggen was too thirsty.  The engine in the gripen is amazingly reliable, has a good power to weight ratio and is reasonably efficient, but it's too damn small.

 

What's more, if the US wants to hip-check the Swedes on the export market and sell more F-16s, they do possess the ability to pull the manufacture license for the engine.

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le epic meme face XD

 

Have a copy of a post I made a while ago:

Here are some words about the JA 37 intercepts of the SR-71 during the 80's. Most of the text is translated or adapted from the book "System 37 Viggen" (Flyghistorisk revy, 2009).

The JA 37 tactics development unit got started quite early on with working on a mission profile for intercepting targets at very high altitudes. The targets considered were the SR-71 Blackbird and the MiG-25 Foxbat; both types were capable of mach 3 at altitudes above 20,000 meters (65,000 ft).

Since the Viggen obviously wasn't fast enough to catch up to the target, the profile they came up with involved the intercepting aircraft meeting the target on a directly opposite course, with intercept vectors and combat control provided by ground-based installations over datalink and/or regular speech radio (in Swedish terminology, the air combat control system was known as "Stril", portmanteu for "Stridsledning och luftbevakning", which means something like "combat control and aerial surveillance"). This meant the JA 37's PS-46 radar would be supported by the ground-based Stril ones, since the intercepting aircraft couldn't catch the target on its own radar in time to climb and accelerate to intercept.

The tactics and armament systems were developed in the JA 37 systems simulator at Saab, with the simulator connected to Stril. For obvious reasons there were no opportunities to practice against our own aircraft in reality. The mission profile started with acceleration in level flight to mach 1.35 at 8000 meters (~26,000 ft). Then the nose was raised to 3-5 degrees above the horizon in order to climb while accelerating further. The maximum altitude was kept within the 16000 meter envelope ceiling mandated during training.

The USAF SR-71 recon missions were commonly known as the "Baltic Express". Usually, the SR-71's entered the Baltic at an altitude of about 21,500 meters (70,000 ft) about 80 km south of Copenhagen, accelerated to mach 2.98-3.0, continued eastwards and then northwards along the coasts of East Germany, Poland and the Baltic states, followed by a left turn westward, crossing the Baltic sea to the Swedish side just south of Åland, then another left turn southward and flying through the narrow corridor of international airspace between Öland and Gotland. Initially the left turn westward south of Åland was so wide that the SR-71's ended up violating Swedish air space, which led to a diplomatic protest which caused the SR-71's to slow down to mach 2.54 during the turn before accelerating to mach 3 again on the southbound leg. Between 1977 and 1988, 322 such missions were flown; in a few cases the mission was also flown in reverse.

Map of a typical SR-71 flight (note the times - wallclock time - noted along the flight path, the violation of Swedish airspace near the top and the Soviets running circles in the top right):

OZX9bLa.jpg

The intercepts would typically be done around the place that says "0910" on the route, or slightly north of it.

Simulator training on the mission profile started in Norrköping at the 13th air wing (one of the first wings to receive JA 37's; it had been equipped with them during 1981) for both pilots and air combat controllers. You couldn't know who ended up getting the intercept, so everyone was trained. The first real intercept opportunity came on October 26th 1982, when a pair of Viggens encountered an SR-71 for the first time. One of the pilots tells the story:

 

We had no extra time for getting into position before the intercept, so there was no margin of error. I got a radar lock on the SR-71 during its left turn north of Gotland and I remember being somewhat surprised by the unusually long target velocity vector on my radar screen. The target altitude was above 20,000 meters, speed exceeding mach 2. Because of the great closing speed, the supersonic climb had to be started at a great distance, greater than you'd think if you hadn't practiced before. The final stage of the intercept went very quickly and it turned out to be a perfect 180 degree attack. The climb attitude increased gradually in an arc upwards in order to keep the target within the engagement envelope presented on the radar screen. The target started jamming our radar, but it kept the lock. I started getting antsy regarding the flight profile after the simulated missile firing, since my nose was pointing very far up and I was slowing down. But aborting now didn't feel like an option now that we had finally gotten the opportunity to try our capabilities against this very difficult target.

When I had "fired" my Skyflash (the Swedish designation for this missil was rb 71; a semi-active radar-guided missile that was really a British improved version of the AIM-7 Sparrow), I looked up and saw a black shadow pass over me and continue to my rear. Just a shadow, I couldn't make out any details.

Normally when you fire a Skyflash you're supposed to maneuver so that you maintain your radar lock on the target until the missile hits. I seem to remember that in this case though I didn't have much room for manoeuvring. I had to concentrate on sloooowly rolling the aircraft around and get my nose back towards the horizon so I could accelerate again.

I think that when we evaluated the mission recording and the simulated missile firing on the ground afterwards, we thought that the intercept could possibly be regarded as successful. But the margins of error when intercepting an SR-71 with a JA 37 were very small. You needed a carefully considered starting position, very precise directions from the ground, very precise flying and, certainly not the least important, that the target didn't change its course at all during the intercept.

The second intercept occurred a week later, on November 1st, 1982, with another pair of Viggens from the 13th air wing:

 

I was over the sea near Gotland when I got the order to prepare for an intercept. I got the target info transferred to my aircraft over data link and presented on my radar screen and tactical indicator screen. I accelerated to mach 1.35 at about 8,000 meters (~26,000 ft) and started pointing my nose up; I had full afterburner on during the entire intercept. I chose the Skyflash on the weapons panel for a simulated firing. The JA 37's max radar lock range was about 60 km and the tactical indicator showed up to 80 km of my surroundings in one direction. I slaved my radar to the Stril data link.

The target info from Stril showed that the target was flying in a westward at mach 2.54 at an altitude of 21,500 meters (70,000 ft) in the far distance. The air combat controller on the ground gave me an intercept position south of Åland and I quickly assumed that the target could be either a MiG-25 or a SR-71.

The target turned left and towards me. The closing speed increased very quickly as the meeting angle approached 180 degrees. The circle on my radar screen that indicated target data provided by the Stril ground installations popped up, indicating an echo at maximum range. I gave the lock command and the PS-46 locked on immediately. The target initiated intense radar jamming, but I didn't lose the lock.

The engagement envelope for the Skyflash was presented on the HUD, the radar screen and the tactical indicator screen. I conducted a simulated firing in the middle of the envelope with an aiming error close to zero. The closing speed was approaching mach 4.5 and the target indication was starting to point upward. I was quickly approaching my ceiling of 16,000 meters (52500 ft) and I was still supersonic.

I briefly got a visual on the target (a SR-71) which appeared charcoal grey as it passed 2-3000 meters above me. I started rolling over, very carefully, in order to bring my nose down. My maximum altitude turned out to be about 18,500 meters (60,700 ft) and my slowest speed during the intercept about mach 1.35-1.45. When I re-entered the normal flight envelope at 16,000 meters I gradually eased off the afterburner.

When I came back to base a phone call was waiting for me, with a colonel at the Air Force HQ in the other end. He was well aware of my intercept and I had a short talk with him, where he asked me if the mission had been successful and if the aircraft's weaponry had worked as planned etc. The general impression was that everything had gone according to the plan.

The recording of the mission was analysed and shown to all pilots at my squadron, as well as to the tactical development unit. We simulated the missile firing on the ground and it was judged a success.

Another intercept worth mentioning involved a group of three Viggens and occurred on January 9th, 1986. The group started southward from Norrköping with the intention of intercept training, but immediately after takeoff it was ordered to prepare to intercept a target that was suspected to be a SR-71. The group climbed to 8000 meters on a southeasterly course and then turned northward over the Baltic sea southeast of Västervik, forming up in a column. At this point the JA 37 had been equipped with the fighter-to-fighter data link, so the Viggens could share targeting data with each other, not just with the ground. All three aircraft conducted a simulated missile firing independently. The intercept started at 13:14 local time and was complete at 13:25; the intercept point was about 50 km west of Visby, on the island of Gotland.

The target was flying at an altitude of 21,500 meters at mach 2.9 and as usual attempted to jam the PS-46 radar. The Viggen group had had plenty of time to climb and accelerate, so when the lead and the second aircraft had passed the target the flight lead called to continue at maximum speed since the mach number at that point was around 2.0. The third aircraft did not reply, though, so the leader asked for his status. The answer was "I'm gliding". The third aircraft had suffered a high temperature engine stall. The engine had stalled briefly, the exhaust temperature rose and the warning light "EXHAUST TEMP." was lit. The pilot followed procedure and turned the engine off, and then restarted it when he descended below 12,000 meters. Having the engine stall at that kind of altitude was very scary since without bleed air from the engine, the cabin would lose pressurization within minutes. The entire group exceeded 18,000 meters of altitude during the intercept.

The fighter version of the Viggen really wasn't what you'd normally consider well suited to high speed/high altitude intercepts. It had fixed engine intakes, which meant it couldn't exceed mach 2 and it ordinarily had a ceiling of 16,000 meters, where its performance was decent for its time but not really comparable to that of purpose-built high altitude interceptors. Flying it at such high altitudes could be risky; the engine and the intakes were operating at the very edge of their capabilities and there was a passage in the flight manual that cautioned against "hammershocks" in the intakes that could possibly tear the aircraft apart if the engine stalled at high speed and high altitude. Nevertheless, in many cases it succeeded with intercepting even such a difficult target as the SR-71 anyway (over 50 successful intercepts recorded by the air force during the 1982-1988 period). The success can be attributed in part to the predictable flight paths but also to the aircraft's excellent data links, which were quite exceptional for its time and made it a lot more capable interceptor than it would otherwise be. Catching up to the target is one thing, but you also need to know where to find it.

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You like the Lansen? Have some more! I posted this on SA originally but it deserves getting spread.

Someone dug up, digitized and YouTubed a 1975 Super8 recording from the Swedish air force's 6th wing/2nd strike squadron. It's cold war as fuck. In those days, men were men, pilots had ridiculous mustaches, safety regulations about low altitude flying were still a thing for pansies, the squadron still flew the Lansen (one of the last squadrons to do so; the strike version left service for good in 1978), and dumb bombs were still a valid weapon choice against naval targets.

The original film was mute, so all sounds have been added in postproduction.

Highlights (but you should really watch the whole thing):

2:00 if you want to skip the briefing and the mustaches

4:00 actual low altitude flying starts

6:20 bombing run starts

8:10 and onwards to the end has some pretty cool low altitude shots, with the shadow of the plane occasionally giving an idea of how low they're flying

9vmEwTd.jpg

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If you were indecisive about buying a Draken, this 1960 Australian evaluation of the J 35B might help you make your decision (does breaking the sound barrier in level flight with dry thrust only sound appealing to you?). Relevant documents start on page 74, report from the test pilot starts on page 87. The same file also contains at least a partial eval of the Mirage III.

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Part 1 - general info, checklists, etc. Similar to the unclassified Sk 35C flight manual in English that's listed in the document thread, but contains more stuff (such as weapons procedures etc).

Part 2 - by far the most interesting part. Describes the airplane as a system and the working principles of its most important subsystems (radar, data link receiver, sights, armament etc) as well as its tactical use. Tons of cool diagrams in here.

Part 3 - performance charts for every imaginable situation and load alternative

Part 4 - more of the same

Climbing to 11000 meters eats about 25% of the internal fuel, by the way. It's a very intercepty interceptor.

For you poor unfortunate souls who don't read Swedish, I might be back later with more interesting tidbits.

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