renhanxue

11 or even 12 G should be attainable at low altitude in a fairly narrow high subsonic speed range (no guarantee the wings will stay attached, however). Above Mach 0.9 and/or above 8 km altitude or so, you start running into a complex combination of flight control system peculiarities that limit the max attainable load factor quite severely. At subsonic speeds the aircraft tends to run into 18° alpha limit first, but at higher speeds the flight control system itself can't always keep up. They fixed that on the JA 37, but for the AJ 37 it wasn't seen as a crippling flaw. See this old post for some more details:

I wrote a bit about the Swedish equivalent of Freedom of Information requests here: Regarding "for a video game": freedom of information requests in Sweden ("begäran att få ta del av allmän handling") have a fair bit of constitutional protection, and in principle the authorities are constitutionally prohibited from trying to determine both who is asking for the information and the purpose of the request. The exception is when it comes to declassification, though - in order to determine if the information can be released, the authorities may have cause to ask you what you intend to do with it, because there is the possibility to release it with usage restrictions. This is essentially never relevant for military secrets, though.

I understand it to mean the former (hold correct approach alpha), but now that you ask I'm actually genuinely uncertain.

On modern air shows they're pretty gentle since it's a museum aircraft, so they don't use the wheel brakes that much. The flight manual procedures for the real aircraft also note that in most cases heavy wheel braking is not necessary when using the thrust reverser and short landing procedures. However, it also explicitly permits going absolutely balls to the wall with both thrust reverser and wheel brakes, if the situation so requires (imagine for example a slippery 800m strip with a bomb crater near one end). There are several flight manual pages of caveats attached to this, however. I'll attempt to summarize the section on short runway landing procedures below. Most of this is probably in the DCS flight manual too, but I enjoy nerding out. Prerequisites The 15,5° alpha no-flare approach must be used. With a heavy aircraft in warm weather this might not be possible because of restrictions on how much of a thrust margin you need to safely be able to go around from a high alpha/low speed approach. Aircraft weight < 14 tons (<80% fuel with a clean aircraft) Crosswind component < 30 km/h Must not be carrying rb 04, rb 15 or Sidewinders on the wing pylons Runway width >= 17 m. Procedure Arm thrust reverser after gear is down and locked (three green lights) On final, the aircraft must be trimmed out neutral in pitch If using AFK, disengage it when passing the runway threshold Reduce throttle to flight idle when the main wheels touch down Ensure alignment with runway heading before the nose wheel touches down Pull gently back on the stick after the nose wheel touches down; the higher the throttle setting the harder you need to pull Increase throttle as required no earlier than 1,5 seconds after nose wheel touches down; however, if the actual engine RPM is at flight idle or lower the throttle may be increased to mil power immediately on nose wheel touchdown Wait until two seconds after touchdown before using the wheel brakes Reduce throttle to flight idle no later than when the REV AVDR/TRANSONIC light illuminates; the rpm should be at ground idle by the time the aircraft comes to a stop. Notes and caveats By far the greatest danger during a short landing is the risk of losing yaw control. Although the aircraft has good yaw stability under ordinary circumstances, the thrust reverser disturbs the airflow over the tailfin, which significantly degrades the aircraft's yaw stability. These yaw disturbances become increasingly severe with higher speed and higher reverse thrust settings. At very high speeds, engaging the thrust reverser degrades yaw stability to an unacceptable degree, even with the throttle at flight idle. Hence, arming the thrust reverser at speeds above the normal 15,5° glideslope approach speed is strictly prohibited, even in an emergency situation. Setting the throttle to full reverse (mil power with the reverser engaged) must not be done before the speed has dropped below 250 km/h. The autopilot's SPAK mode automatically uses a special yaw damping mode while the thrust reverser is engaged, which helps mitigate the yaw stability issues to a significant extent, but does not eliminate them. If SPAK mode is not available (e.g. due to an autopilot fault condition), the thrust reverser must not be used at speeds above 200 km/h, and once deployed the throttle setting must not exceed flight idle, except in an emergency. Do not push the stick forward while reversing at high throttle settings. The resulting reduced weight on the main gear severely degrades the yaw stability, and in extreme cases the main gear may leave the runway entirely. Avoid using asymmetric wheel braking if possible; using only the rudder for yaw control yields higher precision. In case of abnormal yaw disturbances during thrust reversal, immediately reduce throttle to ground idle. Using the thrust reverser on snow or ice may reduce the runway friction coefficient.

Has anyone actually requested declassification of any version of the JA 37 flight manual? Part 4 (flight performance charts) was declassified all the way back in 2012. Things don't get automatically released as declassified in Sweden, someone has to request it and then it gets reviewed, and the review process can involve redacting parts of the requested material. I've gone through this process many times myself. The declassification process is much easier if the documents in question are older than 40 years (to simplify a lot, younger than 40 years = may declassify, older than 40 years = shall declassify, with some exceptions), and the first publication of the JA 37 flight manual should have passed that limit only last year or maybe even this year (probably a 1980 or 1981 publish date). I wouldn't be surprised if most if not all of it would be pretty easy to get declassified today. Later updates to the manual are almost certainly a lot more problematic, especially when you start getting to really late versions like the JA 37D and Di which could carry AIM-120, but early editions I wouldn't expect to contain much if any sensitive information today. Either way though, as was mentioned above, the JA 37 avionics actually have very significant differences from the AJ 37, and the flight performance is quite different too (different engine, longer fuselage, different FCS) so for most intents and purposes it'd be like implementing a completely new module.

I can verify that the Swedish documentation for rb 24 (from SFI J 35F del 2, page 77) agrees with the documentation presented above, saying "[r]oboten är ostyrd ca 0,5 s efter utskjutningen" (the missile is unguided for approximately 0.5 seconds after launch).

viggen in wet weather is a lot of fun

1000 what? The altimeter's pressure setting is in hPa so 1019 is the setting for mean sea level. 1000 hPa is a perfectly reasonable setting, but 9449 is impossible. Either you're reading one digit too much or you're talking about something other than the pressure setting, I think.

There's almost certainly data from actual flight tests in the national archives, the problem is finding the right place to look. As someone with a decent amount of experience in Swedish military archives, I'd say it could easily take a year to find something like that - weeks of digging through indexes to find likely places to look, then months waiting for declassification and weeks to dig through the results, then repeat because you probably looked in the wrong place the first time but now you know more about how the archive is organized. I've been kinda itching to get back to archive diving, but unfortunately the archives have moved so they're way less convenient for me to get to. I used to be able to spend an hour or two on Wednesday evenings after work there (they were only open evenings one day a week), but now it's like 45 minutes just to get there.

Excellent work, this must've been a ton of effort! Weird to see that the top speed is still this extreme, it's been well established that it's too high for years now. The clean aircraft being extremely fast at sea level is one thing, but doing well over M 1.1 with the draggiest loadouts in the arsenal is just wildly off. Some of the weapons are clearly not modeled correctly, and the 11km test is just nonsensical. I'm almost certain the thrust-to-drag diagram doesn't considers fuel consumption, so in reality the aircraft should probably do slightly better than the diagram as fuel is consumed (the diagram is calculated at 100% fuel for loadouts with the drop tank mounted), but that doesn't come anywhere close to explaining the huge differences here - the benefits of slightly lower alpha are insignificant compared to the enormous transonic drag from the stores.

Other way around; the general rule was no lower than 10 meters over water or 20 meters over ground in peacetime. In mission plans and the like you wouldn't usually see those numbers though, you'd see a call for "lowest altitude", leaving it to the pilots to decide exactly how low was appropriate (with safety regulations like the 10/20 meter floor in mind).

To clarify here, ground collision warnings on the AJS 37 are a complex enough topic to have an entire chapter dedicated to them in the SFI. There are three main cases and then a bunch of special cases mostly related to weapon release altitude restrictions. The first main type is bottenvarning (literally "bottom warning"). This requires the HÖJD CI/SI switch to be in position LD while the radar altimeter is enabled, and the trigger condition is radar altitude < 150m while also being less than half the air pressure altitude (e.g. it'll trigger if the radar altitude becomes less than 50m while the pressure altitude is 100m). The second one is metspövarning, literally "fishing rod warning", and is the one referenced in the OP. As MYSE1234 says it doesn't actually use the radar nor does it require the radar altimeter to be active, but it is nevertheless only enabled if the radar is in mode A1 or A2. The manual explicitly says that the warning does not account for upcoming obstacles, only the current altitude. Presumably the thinking here was that if you're doing the Viggen thing at lowest altitude by the book, this warning would only be a potentially deadly distraction, while it's needed if you have to go head down to use the radar. The third one is really a group of warnings that are enabled while the autopilot's altitude hold mode is engaged. The main case here is triggered if the altitude is less than 80% of what it was when the mode was engaged, but there's a whole bunch of cases here that spans a couple of pages of the SFI and I'm not going to go into all the details. It's notable though that if the radar altimeter is active it continuously updates the reference altitude. There's also special case that doesn't look like the other ground collision warnings (fixed ground collision light on the CI, no blinking lines on the HUD) in case of CK37 failure. None of these cases are capable of warning of upcoming obstacles. If it does that in game then that's a bug. Do note though that in the transonic region (M 0.97 - M 1.05) the computer's idea of the altitude can be rather unreliable even if the radar altimeter is enabled, since in the transonic region the computer replaces the pressure altitude with a calculated altitude base on integration of the vertical acceleration.

First, small terminology nitpick so we can all agree what we're talking about: in Swedish (and maybe also in German), all control surfaces are "roder", but this is not the case in English. A rudder is the control surface you use for yaw - the thing you move with the pedals. The control surfaces we're talking about here are called elevons (combined elevators and ailerons). I think the misunderstanding was already cleared up in this thread, but just to make sure we're all on the same page Yes, 22° is the max deflection that can be achieved with a pure pitch up/down movement of the stick, but the missing bit here is that this is both altitude and airspeed dependent. As dynamic pressure increases (that is, you fly faster and/or lower), you get more force per degree of control surface deflection. If the control system didn't compensate for this, the aircraft would be essentially unflyable at high speeds because the stick would be extremely sensitive, and any big movement would rip your wings off. So, the Viggen has two almost literal hydraulic gearboxes (one for pitch and one for roll) that attempt to keep stick force per G the same regardless of airspeed and altitude. The roll gearbox only has two modes, high speed and low speed, and switches between them at 350 km/h IAS. The pitch gearbox though is continuously variable, and at its highest setting (least control surface deflection for a given stick movement), the max pitch-up deflection is only 8.7°. Here's a chart of max elevon deflection by airspeed and altitude, in SPAK mode (from Fpl 37 aerodynamik III): The line at M 0.93 corresponds to the "series trim" kicking in to correct for transonic and supersonic effects, and since control surface effectiveness is reduced at transonic and supersonic speeds, this also coincides with an expansion of the deflection envelope by about 3.5°. We're not done yet though, because there's yet another thing that can mess with the elevon deflection, and that's the "droop mechanism". This is used to add a drooping offset (additional pitch down deflection) to the elevons, and it's controlled by the canard flap control mechanism. This is connected via a mechanical wire linkage to the droop controls, so when the canard flaps are deploying the elevons are continuously drooped at the same time. Unfortunately I don't know how big this deflection is, since the SFI doesn't say, but this is probably at least part of the reason why you're seeing a surprisingly small deflection upwards when in landing configuration - you effectively have some invisible pitch down trim already, to compensate for the pitch up trim change caused by the canard flaps.

The AJ 37 is a strike aircraft with only very limited A2A capability. The fighter variant is the JA 37, and that one does have a cannon and integrated countermeasures dispensers.

The Viggen has absolutely no problems with slowing down fast if it needs to, just turn and you'll get rid of speed in a hurry. Also the thrust reverser really messes up the yaw stability, it'd be very dangerous to use in the air and there are multiple safety interlocks that prevent it from happening.

You basically shouldn't. In the real aircraft there's even a thin lock wire keeping it in the AUT position, which should tell you what level of "don't mess with this" it's on. The specific (and rare) fault condition the switch is supposed to be used for has to do with the automatic engine restart system. There's a flameout detector in the combustion chamber, and if that trips, the engine ignition system is turned on in order to try to restart the engine. This is accompanied by a master warning and the lamp TÄNDSYST on the annunciatior panel (it remains lit as long as the ignition system is on). If the flameout detector is faulty and gets short-circuited so it's permanently tripped, then the ignition system is on all the time, which is obviously undesirable. You can disable the flameout detector (and the automatic re-ignition) by flipping the TÄNDSYSTEM switch to MAN. If you then try to manually restart the engine with the ÅTERSTART switch, the TÄNDSYSTEM switch automatically flips back to AUT. I have no idea if a faulty flameout detector is a thing that DCS can simulate, but there you go, that's what it's for.

razo+r is correct, but to put it in a different way: Sidewinders and the ECM/chaff&flare pods can always be added to any loadout (assuming you have suitable stations free). The gun pods can be used together with rb 05 or rb 75. Other than that, you're limited to a single weapon system at a time. Asymmetrical loadouts are supported though. Compared to a modern multirole fighter this might seem weird but it makes sense in the operational context the aircraft was designed for. It was exclusively made for "one pass, haul ass" missions against pre-planned targets. CAS was not a thing the Swedish air force even considered doing at the time. Mixing weapon systems would have added a lot of complexity to the already extremely complex (for its time) onboard computer, for almost no benefit. The fact that you can't carry countermeasures together with some of the most important weapon systems though is definitely a design flaw and was controversial even at the time; my impression is that the capability was dropped for cost reasons (it was added on the fighter variant JA37 later though). It's important to note though that the normal way the AJ 37 was operated was in groups of at least four aircraft, or more rarely in pairs - almost never alone. If you for some reason really needed multiple capabilities in one mission you just assigned them to different aircraft in the group. Even then though, A2A weapons would not normally be carried for strike missions - the aircraft is completely reliant on its speed at low altitude for survival, and if it gets into a dogfight something has gone extremely wrong. The reason they can be carried is so it can be used to intercept bombers and paratrooper transports in a pinch. The all-aspect Sidewinders were a very late addition in the aircraft's service life. e: To address the actual problem: post your keybindings for TV/T1/T0, that switch has confused people in the past

I responded to the PM all the way back in November but never posted here for some reason, so just to put this out there: if anyone else wants to do this for any language, by all means go ahead! I'm very happy that the writeup is interesting to others. Also, feel free to link to your translations in this thread so people who encounter the English version first can find translations from here too.

Cheeky of you to replace the emergency checklist with the FL/metric conversion chart as seen in Gustav 52... Also, if the screenshots may be believed, the waypoint button labeling (W1-9) doesn't match the destination indicator labeling (B1 in the screenshot).

Crossposting for visibility - @Amarok_73 reports that the LT-KRAN EBK (afterburner low pressure fuel cocks) switch appears non-functional:

Ah okay, it's just a confusion of terminology then, I'd call that switch "afterburner low pressure fuel cocks" (Chuck's guide calling it "manual afterburner fuel regulator" is also confusing, because there is another switch that is actually called that which does something different). I... don't think you're supposed to use that except if the aircraft is on fire, honestly - that entire panel is all switches that are for emergency use only. Still though, if it was modeled and now it isn't then that sounds like a bug to me. I'm not at my gaming PC either though so I can't try to reproduce. I cross-posted to the feedback thread - Machalot has been doing a heroic job of bug reproduction there, maybe they can help.

There isn't, unless he means the detent on the throttle, but then the post makes no sense. I honestly have no idea what you're trying to do or which switch you're interacting with, @Amarok_73. I'd appreciate if you could elaborate.

It's the first one, "säkerhetsavstånd". The ballistics calculation for akan/arak isn't CCIP; the aim point on the HUD is only intended to be accurate at a specific distance from the target, at which point the firing cue is given. That distance should be as short as possible, to allow for maximum accuracy, but if it's too short you risk getting hit by shrapnel from your own weapons. That switch allows you to configure essentially how quick you think you're gonna be on the pullup after firing. RagnarDa explained how it works a long time ago.

Amazing work, thank you so much for doing this! Looking forward to the completed version!

That's the unclassified part, which is almost identical to the one for the JA 37C which is already in the OP (although that one is in English). The interesting changes on the JA 37D were all classified and as such aren't in the unclassified part of the manual.