renhanxue

yeah i'll get right on that in 20 years or so when it's easy to get declassified, that is

Fair, I agree they do, I just always had the impression that the afterburner injectors had the shape of a plate and would be blocking the view down there. But I'm not sure where I got that idea and it would kinda make more sense to not block the flow that much so I'm probably wrong, actually.

Are you referring to the next innermost ring? Are you sure those are actually the turbine blades? (really cool photo by the way!)

lmao I have no idea if it's animated or not, but animating it would just be a pointless waste of resources since you cannot actually see it even on the real aircraft, because the afterburner is in the way. The afterburner is actually considerably bigger than the gas generator, which means that if you're looking into the engine nozzle from the back of the aircraft you're staring down a black tube that's like five meters long, so you can't really see anything in there in the first place. Even if you took a flashlight and shone it down the tube though, basically all you'd be looking at in there is the afterburner diffuser section and specifically the injector plates, which are pretty much the same diameter as the turbine. Here's a photo for reference, and here's a diagram of the engine layout as installed in the aircraft - and keep in mind that behind the nozzle at the back there's the thrust reverser and tail cone assembly as well:

The Swedish air force strike ops with the Viggen only very rarely involved fewer than four aircraft at a time. One squadron tactically in the air was eight aircraft, and the half-squadron ("fyrgrupp" or just "grupp") was really the smallest common tactical unit. The recon aircraft operated solo or in pairs, and the fighters usually at least in pairs, but the strike aircraft almost always in groups of four or larger formations. For anti-ship strikes against multiple surface combatants the doctrine manuals called for employing at least two squadrons at a time, but preferably more - there were strike exercises where six squadrons (48 aircraft) formed up radio silent and did a coordinated strike against a single target, to give an idea of the kind of strike packages they were working with.

Simple answer: the Swedish air force during the Cold War did not do CAS. Full stop. There was no CAS doctrine, the army had no forward air controllers (except maybe at the very tail end of the 1980s, when they started getting something vaguely similar), and the air force and the army did not exercise together. CAS is something you can afford to do when you have air superiority, but the Swedish air force counted on having absolutely no hope of air superiority. The Swedish air force strike aircraft were strategic assets, not tactical, and could absolutely not be wasted on plinking tanks. Strategic high value targets only - invasion fleets, beachheads, bridges, big supply dumps, large convoys, etc. That went for the SK60 as well, although it was far less capable. All of the AJ 37 squadrons were organized in a formation called E1, första flygeskadern. The chain of command was such that the immediate superior of the commander of E1 was the commander-in-chief, or the joint headquarters, which kinda illustrates what level of importance the intended targets would have. E1 could be likened to the USAF Strategic Air Command, but without the nukes. Under some circumstances though the headquarters could offer a military district commander (who would be in command of all forces in his district, typically at the very least a few brigades) a number of strike sorties per day that he could use as he saw fit. He would most certainly not waste these on plinking tanks either, but rather trying to get at supply lines or other strategic targets. CAS doctrine development sort of started to be developed during the latter half of the 1980's though, but it was only the SK 60 squadrons that did it at first. e: actually I went and looked up some sources and it looks like the SK 60 squadrons started developing something vaguely CAS-like earlier than I thought - they started training army-air force coordination platoons as early as the mid-70's. Still though it seems to have been a rather gradual process and they preferred pre-planned missions.

Funny story in the second half of the video - as all pilot tales, take with liberal amounts of salt, of course.

I have to retract my earlier statements about this being impossible, and I apologise for unintentionally gaslighting you, because I found the thread: The SFI mentions absolutely nothing about this, but apparently the mechanism that physically connects the flap linkage to the landing gear lever is actually accessible from inside the cockpit, and it can be unlatched from the landing gear lever with some fiddling (you have to reach in underneath the handle of the landing gear lever and push on a latch down there). You're clearly not supposed to do this - the flap linkage doesn't have a handle, for one thing - but it is possible. I based my previous statements in this thread solely on the manual which just says that there's a physical linkage - I interpreted that as it being permanent, which it is not.

Google recently did as they are wont to do and broke a bunch of links for some convoluted reason. Seems to only have applied to people who had never opened the link before, so it probably didn't affect any of the usual suspects, but if you found this thread recently and one of the Google Drive links asked you to log in and request permission to view the document, try again now and it should hopefully work without any of that nonsense. Let me know if it doesn't.

There is an override, it's marked FÖRBIK AVFYRNKRETS (expands to "förbikoppling avfyrningskrets" - override firing circuit) and is located all the way to the rear on the right side of the cockpit, with a flip-up cover on top of it. It's clearly not implemented though (or it's implemented but defaults to being switched on...).

As far as airframe differences go, the JA 37 is as mentioned longer (because the engine has an extra compressor stage), it has different elevon actuators, the drop tank is different, it has a conformal gun pod underneath, and a bunch of data link antennas all over. The hard part though would be the cockpit and avionics; only basic controls are the same as on the AJ 37.

On one hand interviews with someone who was there are always fun; on the other hand I deeply despise these popular military history channels. They have no interest in actual history, they just shovel out polished and "cool" but poorly researched content using other people's source material for the sweet ad revenue. In this case almost all the raw Lansen footage shown is taken directly from this video: Which is just a compilation of some guy's personal 8mm film recordings from the 60's, which are used uncredited, and quite probably without permission as well. Quite a bit of work went into restoring and publishing this and it may even be copyrighted still. For some actual content, here's some more personal pilot recordings that have popped up over the last few years: This is from the last days of the Viggen and as such some of the highest quality footage of the Viggen in actual operation that I am aware of. All JA 37 though. This is the only footage of a Viggen dogfight exercise that I know of (apart from some very short clips from this on the same channel). Also JA 37, of course.

I agree with MYSE1234; the SFI seems to indicate that the range markers are written with the same electron beam as the radar image itself, so they should be black/grey (as opposed to the symbol beam which leaves a white image).

It really is and ever since that manual page was declassified I've always wondered why it has that weird and seemingly completely arbitrary low release altitude restriction. I assume there must be some reason for it, but I doubt we'll get any reasonable explanation in the near future because the development documentation is probably not going to be declassified for a while yet.

I don't know how well the BK90 anti-UXO measures actually did work (that's almost certainly still classified) but I do know that a great deal of effort was put into it and for good reasons. Remember the weapon system came out of the Cold War, and as such the Swedish doctrine at the time meant that it would have been designed for almost exclusive use on Swedish territory. Leaving behind significant amounts of UXO would have been a big headache for the Swedish authorities afterwards and a highly undesirable property of the weapon.

The canard flaps only have three possible settings: fully deployed (+30°), retracted (-4°) and extra retracted (-7°). That last option is used when flying with tail-heavy external loads (e.g. AKAN/ARAK pods or the ECM pods) and increases negative pitch authority as well as roll authority at supersonic speeds a bit. The option is controlled by a switch in a technical compartment on the fuselage and is set by the flight mechanic during the rearming procedure, if loadouts that warrant it are carried. There are no provisions whatsoever for any other flap settings anywhere on the aircraft. What you might be thinking of though is that as the flaps move, they automatically re-trim the pitch continuously so you don't get a nose-up trim change when they deploy. This is done mechanically - as the flaps move, they act on a pulley system that mechanically interacts with the pitch controls to droop the neutral position of the elevons correspondingly, without any perceived trim change for the pilot. Well, if you make changes to the aircraft you end up with a changed aircraft. But this is a simulator and the goal, I would assume, is to emulate the real aircraft as it actually worked. I'm not an engineer, but I do know how the AJ 37's flight control system works, and I can tell you with a great deal of confidence that both having cockpit-controllable flaps and flying the aircraft with the radar stick would require major physical changes to the aircraft. The AJ 37's flight control system is really neat and interesting, but it predates true fly-by-wire and is mostly mechanical - it's physical linkages, pulleys, differential gearings and hydraulic servos almost all the way down. The electronically controlled part of the system is actually physically separate from the rest of the flight controls - the autopilot is in charge of that part, and it works exclusively with the outer elevons. Normally (with SPAK enabled) the outer elevons just follow the inner ones, but with the autopilot adding its oscillation dampening on top. If you disable SPAK you lose access to some authority on the outer elevons, because that's reserved for the autopilot's own use only (for oscillation dampening). If you somehow hooked up the radar stick to the flight controls electronically you'd only have access to those outer elevons, nothing else, because everything else is purely hydromechanical. The electronics simply follow the hydromechanical system; there is no interaction the other way around. They did things that way because they didn't trust the electronics yet and wanted the aircraft to still be controllable (although limited to half the elevon authority) in the event of an electronics failure. The JA 37 is a bit closer to actual fly-by-wire but still not quite there (I don't recall off the top of my head exactly how it works but I'm quite certain it retains the basic hydromechanical system, although the electronics have more of a say). As for the canard flaps, the landing gear lever is literally connected via a pulley system to a valve that controls the hydraulic jacks that actuate the flaps. That's it, "down" or "up" are all the controls you get. I mean, I guess you could add another separate lever connected in the same way but not connected to the landing gear, but that's a major physical change to the aircraft and we're well into fantasy territory at that point. It might be worth mentioning as well that on the JA 37 they actually simplified the canard flaps even further and removed the "extra retracted" position as well, so there's only deployed and retracted, nothing else.

It's pretty apparent at this point that the Viggen is every practical sense a hobbyist project. I'm almost certain nobody has worked full time on it in a very long time now. It was always sort of an enthusiast thing developed by people who had other jobs on the side, and it's extremely impressive that it even got released, and even more so that it's actually in a pretty good shape. Still, it's very apparent that updates happen only when some enthusiast goes above and beyond to work on it, and then there's apparently no real release management/product life cycle management for it because entire updates have gone missing without anyone noticing it on Heatblur's end, more than once. In other words, I think there's certainly someone at Heatblur (or multiple someones) who really does care and who wants these things to be fixed, and as such it's wrong to say that these issues will never be fixed. On the other hand, there's clearly no real production software product life cycle going on here, and who knows when someone might find the time to work on it. Last time I brought this point up I got a thoughtful and polite response from IronMike, which I really appreciated, and where he basically said that I was wrong to call it an enthusiast driven project. He obviously knows how things work internally at Heatblur and I don't, so I can't really argue against that on a technical level, but as a bystander I must say I have a really hard time seeing how I'm wrong in any practical way. He made that post almost two years ago, and while there have been a number of bugfixes since then, what's actually been delivered in that time is more consistent with one guy working maybe an hour or two a day than anything else.

[citation needed] How would they have done this? To the best of my knowledge there is absolutely no way to control the canard flaps from the cockpit, except indirectly via the landing gear lever (gear goes out, canards flaps go down together with it).

Why do you think it should be breaking Mach 2? The flight manual certainly doesn't say or even imply it is capable of doing that. At ISA -15° it may be capable of touching the Mach 2 line (or at least it's theoretically capable of sustaining that speed in level flight) but I'm not sure you could get it to accelerate to 2.0 in reality without running out of fuel. It doesn't have variable geometry intakes so it really has no business above Mach 2. I believe it is underpowered in DCS on mil power, though.

IIRC the JA 37 flight manual has a 1981 publish date so with the standard 40 year declassification term it should in principle be possible to get it declassified now without too much trouble. Better be prepared to wait a year or so for the national archives to handle the request though.

Again, I don't think anyone has actually argued that the real aircraft is even remotely capable of reaching those speeds at sea level, let alone sustaining them, so this is sort of academic. The speed alone is well past suspension of disbelief on its own.

Agreed that is probably slightly faster than it should be, even clean. Thanks for checking!

We already established above that anything above 1500-ish is unrealistic even clean, as both Saab employees and the flight manual agree on this point, so there's no need to be snippy. Saab marketing certainly hasn't ever made any claims about the speeds you're seeing, and nobody else has tried to argue otherwise either since last time this was brought up. It's good to have numbers though, and I agree it's a significant bug, so thank you for testing it. I'm curious though how closely it matches the flight manual numbers clean.

Amazing work! That's a suspicious discontinuity if I ever saw one...

See this thread for some charts from the SFI (flight manual for the real aircraft): The chart is for payloads in group 1 (drop tank and maybe a sidewinder, I don't remember off the top of my head). 2100 km seems optimistic and I don't know where the figure comes from. I suspect that for a truly optimized distance economical flight you'd probably want to start lower and climb gradually as fuel is expended though. That's just speculation on my part however. Did you jettison the drop tank in the test flight by the way? edit: ok, went and looked. group 1 payload is represented by drop tank, 2x rb 24 and the KA and KB countermeasure pods. SFI says you should be able to do almost 1600 km clean with 5% fuel reserved for taxi and 15% in reserve for landing, or maybe 1650 if I'm reading these charts right and you start climbing to 10km during the later half of the flight. 2100 km does sound rather optimistic to me but might possibly be achievable with the perfect flight profile and small margins.