renhanxue

Short for "spännvidd", which means "span", or specifically in this context "wingspan". For the AKAN range estimation, yes?

Apologies if I'm coming off as overly pedantic, but the RM8A is a turbofan. On dry thrust it does indeed lose thrust with increasing airspeed, as you say, but with the afterburner engaged thrust is either more or less constant with airspeed (up to the transonic region, on low afterburner thrust settings) or increases with airspeed. At max zone 3 the thrust increase is almost - but not quite - linear with increasing airspeed from standstill to Mach 1.1 at sea level. Here is the thread I was talking about, please refer to the thrust-to-drag diagrams therein if anything is unclear. As far as I know most military afterburning turbofans behave more or less like this; the RM8A just happens to have a particularly pronounced thrust increase in afterburner because of its large bypass ratio.

The thrust curve is a bit simplified in that diagram - it's not quite that linear with IAS, I'm pretty sure (compare to the thrust charts in the SFI). Also, thrust numbers that are quoted in encyclopedias and the like are usually given for an engine static in a test rig on the ground. Mounting it in the aircraft reduces thrust because of losses in the intakes and to auxiliary equipment such as the generator, bleed air etc, but increasing airspeed increases thrust while on full AB because it gets more fresh air to burn. In other words, actual thrust in the air in different situations is quite different from the encyclopedia number. See my thread about the Viggen's afterburner for a lot more words about this.

Because ECM in the real world doesn't work like in DCS.

Yep, the manual has a couple of pages that are just long lists of four-digit numbers that map to certain geographical reference points (lighthouses and geographical features were common as Corrigan says, especially along the coasts, but other landmarks such as bridges, road intersections and towns were also used). When I posted it in the Viggen FB group it immediately turned out that a number of old pilots still knew a lot of them by heart, 15 or 20 years later...

Will try to remember checking on Wednesday (I'm back at work again and national archives is only open in the evenings on Wednesdays)

Much like a Muslim hafiz learns to recite the Qur'an by heart, I have learned to recite the holy text of the Viggen... ;)

Fpl AJS 37 SFI del 1 kap 1 flik 8 sida 5. Page 119 in the PDF. (It sounded familiar but I couldn't remember if I had seen it in the SFI or not so of course I had to go look it up)

well, "find"... these are things I know by heart, you know :V The only reason I didn't post it earlier was because you didn't ask. I'm not kidding, I think every single link on uniformsdetaljer.com is in the purple "you've clicked this before" state in my browser since years and years ago and it's very rare for me these days to see a historical Viggen photo I haven't seen before. (I think I may need help, please stage an intervention)

May be a bug. The trigger should be inhibited while the nose gear is compressed, but there is an override button (FÖRBIK AVFYRNINGSKRETS).

The white logo with a 3 in it is the emblem of the 163rd fighter squadron (3/F 16, "Petter Gul") out of Uppsala. Here it is as a helmet sticker: Older version from the Draken era: The building outlines in the bottom are Uppsala castle and cathedral - the silhouettes are sorta iconic for the city since it's on a big flat plain and the castle and cathedral are both on a ridge that make them stick up far over everything else. "Östra Aros" is an older name for the city. I grew up there and there were Viggens making noise over the city almost every day for most of my teenage years. The mustang rider emblem originates with the early days of the 16th air wing, when it flew surplus Mustangs. The Viggen Facebook group is by far the best source of historical Viggen photos on the entire internet, there's nothing that even comes close. For squadron badges and such things see uniformsdetaljer.com.

Of course you just happen to have one of those lying around... (seriously though, that's awesome) edit: what does the black/yellow warning label on the side of the box say?

I do believe the ships try to jam you, yes.

This is a good and pedagogical explanation, but it unfortunately gets a fundamental point wrong. In practical terms it's fine and the advice is functionally correct, but I am the king of nerd trivia and will not stand for misunderstandings of the underlying technology ;V The color has nothing to do with the range. The range is translated into position on the screen. The very bottom of the screen (where the sweep originates) is the position your aircraft, and "further away" is up. How far away the top edge of the screen is, is determined by the range setting (number in km shown in red in the lower right corner of the screen). The color on the display is the strength of the radar return (as in, how much energy we got back) - no return is green, as you say, and a strong return is black. How strong the return is depends on a multitude of factors, but most importantly what material the lobe is bouncing against and its angle relative to the lobe. The reason the black returns in obstacle detection mode aren't just thin lines is that the antenna lobe has a height, so a thin line means a vertical cliff face (entire lobe returns from the same distance) and a broad band means a slope (lower parts of the lobe return before the upper parts or vice versa). Th Viggen's radar is a monopulse design that uses lobe shaping, so exactly defining the size of the lobe is tricky, but if I understand the diagrams in the SFI right, obstacle detection mode has a lobe that's about +/- 6 degrees in width (in other words, 6 degrees to each side of where the antenna is actually pointing) and 2-3 degrees in height. In map drawing mode, the lobe is shaped the other way (wide in height, narrow in width), which the SFI claims gives a more nuanced map image (I'll take their word for it... :V). It is obviously true though that the strength of a radar return decreases with distance (the radar equation tells us so), so you'd think that you would be right anyway. However, the Viggen's radar has a "controlled damping" function (really no idea how to translate that, "styrd dämpning" in Swedish) that compensates for signal strength dropoff over range, so a given target with a given RCS will always be displayed with the same intensity regardless of range. In obstacle detection mode this is always active, but in some modes (including map mode) you can turn it off with the AS knob (mode 0 does not always disable it; try mode 3, 4, 5 or 6, but I'm not sure if any of those actually work in DCS). Passive mode on the radar has nothing to do with the RWR, by the way. It just does everything the radar normally does except actually transmitting. The only things you can see on the radar screen in passive mode (other than symbols? don't remember if those are drawn, but they definitely can be, they're drawn with a different ray gun than the regular sweep) are jammers that are either specifically targeted at your radar or transmitting broadband noise. The radar does not gain any extra receiving powers or signal processing abilities in passive mode, so you won't see things like, say, air search radars that operate on a different frequency.

6 missiles. Full A2A loadout on the JA 37 is 2x rb 71/Skyflash + 4x rb 24J (later rb 74, but not when this manual was written). The difference between the RM8A and RM8B is (proportionally) bigger at max dry than at max zone 3, IIRC, but I don't have exact numbers (go look it up in the SFI yourself, there is a thrust diagram ;V) Also, there's a tiny little load factor graph for the AJ 37 in the aerodynamics compendium, see https://forums.eagle.ru/showpost.php?p=2898721&postcount=2802

Quick and dirty translations of what people probably think is the most relevant:

Added SFI JA 37 del 4. Performance charts, performance charts everywhere, including some that are missing from the corresponding manual for the AJ 37, such as zoom climbs and turn rates.

Yes. One air-to-ground weapon system at a time only. Choose one, then add countermeasures and/or Sidewinders to it if you want. Exception: you can mix the autocannon pods with the rb 05/rb 75.

Minor inconsistency on the left panel: "H <12" used under engine failure, but "alt <9" used under abnormal thrust. Otherwise, looks great! Nice job!

I finally walked my lazy ass back to the national archives and photographed the declassified aerodynamic performance part of the JA 37 flight manual (aka. the only part that's been declassified), soooo, turn rate chart: Standard atmosphere (ISA), altitudes 0, 4, 8 and 12 km, clean configuration, 80% fuel remaining. Vertical axis is turn rate in degrees per second, horizontal axis is speed in Mach. The solid lines show both the maximum possible turn rate achievable by the airframe with regards to load factor limitations and control surface authority etc (so the max instant turn rate) and the turn rate at three given load factors (labeled as "Nz = x"). The dashed lines show the engine-limited turn rate at max dry thrust, max zone 2 and max zone 3 - that is, the sustained turn rate. Keep in mind though that the AJS 37 has slightly less thrust, is less resistant to compressor stalls at high alpha and has less control surface authority, so it's all around a bit worse at this. I'm PDF-ifying the entire manual right now, will post in the documentation thread when done.

Don't flare. Like, at all. Slam the main gear into the ground and then push the stick forward and slam the nose gear down too. It's the standard procedure. 400 km/h is wayyyyy fast, too. Higher alpha!

A liter is a liter yes - not sure what's up with the drop tank, though. As I understand it, the new fuel had a slightly different capacitance, which made the fuel meter show higher values (the fuel sensors are basically capacitors which chance their capacitance and therefore AC resistance depending on the fuel level in the tank). This is all hearsay from the Viggen FB group though, I don't have a source on this and it's not in the SFI as far as I know.

They changed fuels between the AJ 37 and AJS 37 to a new one with slightly different density, IIRC. That's why there's a red sticker in the cockpit next to the fuel gauge that says (if memory serves) FLYGFOTOGEN 75 or MC 75 or something to that effect. Yes, it's basically an "unleaded fuel only" sticker ;V

Some foggy memory is telling me that the rb 04 and rb 15F have the same warhead, but I may be (likely are) entirely wrong on that and please post a source on warhead weights or something if you have one That depends on the ship and how good the damage control party is. Against something like a WW2 destroyer, absolutely, single hit kill by ways of breaking the keel is quite likely. Against something bigger and more modern? Much more unlikely, if you don't get that massive structural damage you may or may not get a (temporary) mission kill but most likely not a sinking. (disclaimer: the above is speculation and I am not an expert in the field) See also xkEfLG2micU

Well, since you asked so nicely... It should be noted though that these are not actual emergency checklists, they're just HELP THE AIRCRAFT IS ON FIRE WHERE THE F*** IS THAT EMERGENCY CHECKLIST quick reminders for things you should know by heart, and as such they are very terse and probably incomprehensible if you don't know or have access to the actual emergency checklist. I have attempted to preserve the tone and brevity of the originals in the translations, as far as possible, because I think they're kinda awesome :] Without further ado, left side: Starting from left, let's take it one column at a time. Okay, let's puzzle this one out - it is so cryptic that it resembles arcane wizardry even to a native Swedish speaker and it's hard to understand for me without consulting the full checklists. MTG is marktomgång, ground idle. Then, "alt <12" should be read as a separate checklist item and means "reduce altitude to less than 12 km" (and an implied "before proceeding to next item"). ÅTERSTART is the engine re-start switch - hold for 2 seconds. BRÄNSLEREGL MAN we know from the HUD checklist; the "<9" means "once below 9 km altitude". "- no rpm/temp 20 s -" expands to "if there is no RPM or exhaust temperature increase for 20 seconds, then..." The rest should be entirely comprehensible. Moving on... This one isn't nearly as cryptic. ɑ and nz are of course alpha and load factor ("G's"). Then there is one word/phrase that's kind of a nuisance. The phrase "ej typenl" (expands to "ej typenlig") directly translates to something like "not according to the type", and is rather diffuse in Swedish too. I believe what is intended is to express something like "if the problems are worse than what you would expect and/or what the aircraft is rated for", but you are welcome to make your own interpretation or suggest a better translation that fits within the minuscule space available... :music_whistling: I'll get to the exact definitions of "ABORT" and "FLY GENTLY" later. Last on the left side, with an arrow coming from the compressor stall checklist that should be interpreted as "if compressor stalls continue, or..." With what we've previously learned, this one should be possible to solve, but for the sake of clarity: FTG = flygtomgång, flight idle. Reduce altitude to less than 9 km. BRÄNSLEREGL MAN, but if the problems get worse, set it back to AUT. Monitor EGT, try not to exceed 570°C. JUMP is a literal translation that would be more accurately translated as "eject", but I refuse to change it since it is clearly better this way. Continuing to the right side, again from left to right: LT-KRAN EBK = afterburner low pressure fuel valve. The rest should be obvious. So what is this checklist even for? The heading is particularly cryptic but this is the checklist for a simultaneous generator failure and RAT failure, so you have no AC at all here - only DC power while the battery lasts. "One attempt to re-engage" refers to the generator; only try to reset it (or re-connect it) once. The RESERVSTRÖM switch is the manual way to extend the RAT (it should extend automatically), then follow the checklist for generator fault. If you still have no AC power, find best possible weather, try to maintain visual contact with the ground, and consider the possibility of following a wingman to base/landing. Switch radios to FR24, try to land within 15 minutes (battery should last that long but no longer). Finally, a little bit of terminology: ABORT/ABORT MISSION: abort mission immediately and return to home base, or if that is not possible, to any suitable base. LAND ASAP: abort mission immediately and return to closest suitable base. FLY GENTLY: handle the throttle carefully and smoothly. Do not use afterburner or autothrottle (AFK). Avoid quick changes in altitudes, high G loading and high roll rates. LEAVE THE A/C: eject. The situation usually permits following the ejection checklist. EXIT ASAP: ordinary exit procedure when the aircraft is on the ground is followed, but quickly. My translations are better and come with more trivia ;V (this is because I am a nerd with tons of time to spend on this inconsequential detail)