renhanxue

AMA stands for "ask me anything" and is common on Reddit, a general forums/news/community site. Leatherneck did an AMA thread in a Reddit flight sim community called hoggit a while back, where people asked a lot of questions and got a lot of answers. You can find the thread here.

You can't really lock on anything with the PS-37/A, not in the sense you're probably thinking of. It doesn't really do the whole "follow a target" thing. What you get is raw video - a mostly unfiltered view of the radar returns, in all their greenish monochrome glory. Unlike literally every other radar system on the planet, strong returns are dark/black while the background is bright green. On this raw video display it is your job to try to figure out what returns correspond to what parts of the terrain. Finding something as small as a tank on the radar scope even at the shortest range setting is most likely exceptionally difficult - it was really designed for finding fairly large ships on open sea. There is one feature that may help with detail studies of interesting spots, though - you can set the radar to compensate the image on the scope for the aircraft's velocity, so the area on the display stays where it is while your aircraft is moving (well, until you pass the area or fly out of the radar's area of coverage). What you should be able to do reliably with the radar scope is identify terrain features. If you see a tank column on a road with your mk 1 eyeball (or someone else - like a FAC - sees it and tells you about it) you can probably make out the road on the radar scope, and that means you can program the coordinates for the bk 90 using the radar instead of having to punch them into the computer one digit at a time. Move the cursor on the radar scope to where you want the bk 90 to go, press a button and there you go, now that point is your target waypoint and where the bk 90 will go. You can now turn the radar off, if you like. Approach the target waypoint with the appropriate weapon and master mode selected and the computer will tell you on the HUD when it's time for weapons release. The bk 90 does the rest on its own. Now, bk 90's inertial guidance orients itself in relation to an earth-fixed geographical coordinate system (in practice, latitude/longitude), not in relation to the aircraft. The radar doesn't know anything about that coordinate system, it only knows about where that point you marked on the scope is in relation to the aircraft. However, since the aircraft's navigation system knows the aircrafts absolute position, the target's position can easily be calculated from that and the information from the radar. You can run into problems though if you program the bk 90 with coordinates you get from someone else (or even ones that you yourself enter earlier during the flight or even in the briefing), and it turns out on launch that your navigation system has drifted from your true position. Since the bk 90's navigation system is slaved to the aircraft's during flight, any error will transfer to the weapon and it won't hit where you want. Using the radar ranging method essentially just makes the target's position "drift" exactly as much as the aircraft's navigation system has drifted.

Probably, yes. Ammunition intended for display purposes that is painted as if it was live for realism reasons can have a green band around it to mark it as inert. I'm looking at an old copy of the marking standards though which says the band is supposed to be in the other direction (around the length of the round) but that's probably what it means. edit: oh, it's not mentioned in the standard (it's old, dates back to the 1950's), but it's most likely a simulation round. Simulerrobot 75 (inert Maverick with a live seeker head so you can use the scope in the cockpit) is marked in the same way.

Ammunition (of any kind) painted green in the Swedish armed forces before the NATO standardization took over denotes that the round is an inert dummy. Usually this is also accompanied by a marking that says "blind" somewhere. I think Leatherneck doesn't mean that though. There was also a screenshot with a green-ish rb 75 with a yellow ring (which is weird because the yellow ring would usually indicate a live explosive warhead - inert missile body with live warhead?).

You also gotta keep in mind that the amount and complexity of objects/lines that were possible to render on the HUD was quite constrained by the available CPU time in the computer. I suspect that's a factor that contributes to some of very minimalist design choices (for example you tend to get moving lines instead of numerical readouts, and there's some weird symbol recycling like the "wings" of the flight path marker being used to indicate radar lock when firing rockets). On the other hand I also suspect - although this is entirely speculative - that they were concerned about sticking too much information on the HUD and overloading the pilot with information. I mean, it's hardly a very busy HUD in the first place but there's still a low altitude declutter mode for it.

It does mean stage 2 afterburner, yes, but there are three stages total. "Max zone 3" is what you say when you mean max afterburner (there is a bit of throttle adjustment possible within each zone).

He's referring to the family of 9mm practice weapons for the Swedish recoilless rifles (granatgevär m/48 and m/86 as well as pansarskott m/68 and m/86). On the grg (Carl Gustav, in international parlance) this is a dinky little single shot 9mm pistol-like gun mounted inside what is essentially an inert round for the real thing. On the single-use launchers (Miniman and AT4) the practice weapon is mounted fixed in the main weapon's tube since, well, single use. When you fire the weapon as normal the 9mm practice weapon goes off with a rather anticlimactic "plop" (the muzzle velocity is subsonic) and you get a tracer round that has ballistics similar to the real thing out to maybe 150 meters. While it's a lot less dangerous than a real 84mm HE or HEAT round, it's effectively still a pistol round and normal range safety rules apply. It's mainly intended for practicing the handling (and in case of the grg, reloading) of the weapon over and over again until it's reflex. For actual aiming practice there's also a 20mm variant which is actually recoilless and matches the ballistics of the real thing a lot closer throughout the normal firing envelope. Both of these also have the advantage of not making a gigantic overpressure blast, which is good for work safety reasons (there are medical limitations on how many of these you're permitted per day in peacetime). e: beaten again, I type too slow

Not during the Cold War. The standard was similar, but different enough to be confusing. For projectile weapons of caliber 20mm and greater, hand grenades and rockets, the base color of the body of the round is as follows: Black: AP (kinetic), APHE, HEAT Red: SAP (semi armor piercing) Grey, unpainted or "special surface treatment": HE, canister, smoke, incendiary, illumination Yellow: HE (60mm caliber or less only) Green: inert (or mockup round) Additionally, there should be a ring painted on the round (or around the warhead, in the case of rockets where the warhead and the rocket body count as two separate rounds) that denotes the type of warhead, as follows: Yellow: explosive (omitted if the round is already yellow) Orange: incendiary Light grey: smoke Blue: practice (if the round is manufactured solely for practice use, it can be painted entirely blue) Brown: dummy (inert warhead with the appropriate weight but no effect) In the case of rockets they usually seem to have painted the entire warhead in this color - the marking standard mentions that "for ease of manufacturing, the ring may sometimes be extended to cover the entire body of the projectile". Additionally a black ring may be added to denote that the round has some armor piercing ability (for example some HE rounds with thicker walls that still aren't quite SAP). Special cases (going down the pedantry rabbithole now just for the sake of it): - illumination rounds have the word LYS in white somewhere on them, and usually the duration of the light is also added - tracers are denoted by either a ring around the tip of the projectile or the last two digits of the manufacturing year of the tracer, in the same color as the light of the tracer itself (exception for some yellow rounds that have tracer as standard where this may be omitted) - the letters RSV ("riktad sprängverkan", shaped charge) is sometimes added to HEAT rounds - canister rounds are marked with the letters GRKT ("granatkartesch") Ammunitionskatalog för flygvapnet has pictures of all of this in action. Live rb 75's are white (counts as "unpainted", I guess) with a yellow ring, HEAT rockets are grey with a black warhead with a yellow ring, practice rockets are grey with a brown warhead, etc. Green with a yellow ring would be rather confusing since it would indicate that the round is inert but has a live warhead. e: RaXha got there first, with a handy illustration to boot.

Rb 04E max range 35 km? Do you know something I don't? The real manual (older versions) recommended 20 km and said the max range was 24.

Function check is perhaps better translated as "self-test" and does exactly what that implies. Basically all systems on the aircraft plus most of the guided weapons have some kind of self-test functionality which you mainly access via that mode. A lot of it is mainly for use by ground crew during routine maintenance and modelling it would add a huge layer of complexity for basically no gameplay value at all - it's just busywork. By the way, I really like it that some sections of the manual are basically direct translations of the corresponding sections of the real SFI :V The English phrasing could use some improvements in places though - I noticed quite a few odd wordings in various places. I think in some cases where the Swedish uses "indikator", a better English translation would be "display" - the radar screen is one example.

This is great! By the way Cobra/Jedi/swither/whoever, how are you going to handle inputting coordinates into the waypoint system in Nevada? I think on the real aircraft you can input the coordinates in any order (lat/long or long/lat) because the computer just cheerfully assumes you're somewhere in northern Europe east of Greenwhich, but this is not possible according to your manual and in fact you have to input them backwards. Thing is though, in Nevada the longitude is somewhere around 115° west of Greenwhich, but the data panel only has two digits for degrees. Are you just going to tell people to input longitude minus a hundred, or are you going to chop off one digit of precision?

Well, capable compared to what? As a delivery platform for unguided bombs and rockets, sure, whatever, the later F-4 Phantom versions could do the same thing better around 1970 (disregarding that it's a twin engine two-seater with all the cost issues that implies). But what other medium fighter-bomber could deliver standoff ASM's in 1970? I'm pretty darn sure there weren't any. Now, by the 1990's the AJS 37 was certainly showing its age compared to the later models of the 80's digital era aircraft like the F-16, F/A-18, MiG-29 and Su-27 since it never really got much in the way of mid-service upgrades, but everything is relative.

Thank you! I'm glad other people appreciate the aircraft and its intricacies as much as I do :)

The autothrottle is fairly simplistic and mainly useful for landing - if you enable it with the gear up it simply attempts to maintain a reference speed of 550 km/h IAS, and you can't change that. With gear down though it does try to help you maintain proper glideslope. The HUD is a pretty big topic. The nav mode is fairly simple but there's a whole bunch of different modes for different weapons that would require a long-ish writeup that I can't be bothered to do right now. For the basics, though, see here and I guess here. Moving on, the main stick is fairly straightforward: 49 is essentially the master arm switch - there are no other weapons arm/safe controls in the cabin. It also has a bunch of side effects for different weapons. For example, the protective nose cover on the rb 75 (Maverick) is jettisoned and the TV seeker is started when you arm while having rb 75 selected on the weapons panel, so you need to arm well before you see the target so you can adjust the brightness/contrast on the scope, while on the other hand if you're firing rockets you only want to unsafe when you have the aim point established on the target because that starts the lead calculations, and so on. 51 is a weirdly underused button considering its highly prominent placing - it's used for calibrating the course gyro while on the runway and for updating reference altitude for the current waypoint in the nav system. While the HUD is in the low altitude (declutter) mode you can also toggle a few different display modes with this button (course scale visible or not, for example). 52 triggers saving of a bunch of important variables in the flight data recorder (they're saved periodically anyway but this forces a save right now). It was supposed to be used in case of in flight problems and/or minor emergencies for troubleshooting on the ground, and I can't see that being all that useful in DCS. As far as I know the trigger only has one stage - there is no intermediate detent.

I did the throttle handle quick and dirty, might do the others later. #1 is a lockout latch that prevents you from moving the throttle back past the ground idle detent - pull it up and move the throttle handle all the way back to turn the engine off and close the high pressure fuel cocks. #4 is a countermeasures "panic button" for the flare/chaff pod (KB). Press and hold to dispense flares and/or chaff continuously (one flare every three seconds and/or chaff in a 2s dispense, 2.5s pause pattern). Getting flares, chaff or both depends on what the three-way dispense type switch on the KB control panel located just under the canopy edge on the left side of the cockpit is set to - R ("remsor") for chaff, F ("facklor") for flares, and R+F for both.

I'm pretty sure someone (BravoYankee4, I think?) translated an entire cockpit layout diagram. It's probably around, eh, 350 or so pages back in this thread... ;V edit: wasn't far off, here, then corrections and updates here and on the following pages. But it's not that detailed with regards to the sticks and throttle. By the way, there are actually three sticks - radar, rb 05 and the plain ol' control stick.

As I understand it, yes (but the manual section that deals with this is quite complicated and features gigantic flowcharts and a bunch of maths, etc, so caveat lector). Without QFE to give the computer an idea of where the target is, the radar won't activate. You'd think that it would be possible to implement automated QFE detection by combining information from the air data system (static pressure) and the radar altimeter, but I guess space for clever programs was at a premium in the CK37. (edit: Just realized, I made a brainfart with the QFE detection stuff - the unknown you're seeking is the target's altitude, and your current altitude AGL and the current air pressure are tangent to this. The radar altimeter isn't of any help.) Yep! The gun pods use exactly the same system - the manual covers both together. Interestingly, I think a very similar thing is also possible for attacking air targets with the gun pods - if I'm understanding the SFI correctly the radar can also do the same kind of automatic "lock" and ranging in that case too, despite not being intended as a fighter radar at all.

The dot in the center of the HUD is the actual aim point, not the aircraft's velocity vector. The reason you have to set QFE before the attack (that is, set the altimeter so it reads zero at the target's altitude) is that the slant range to the target is calculated with simple triangulation - the computer does simple trigonometry using only the pressure altitude and the sine of the dive angle and then corrects for ballistics and wind etc to give you a good impression of where the rockets are actually going to hit. Cobra did the attack with the flight phase selector in the NAV(igation) mode, which means the triangulation is all you get as far as target ranging goes. If you switch it to ANF(all), which means "attack", you can also get radar ranging! If the triangulated slant range to the target is less than 7000 meters, the roll angle is <45° and the dive angle is >5°, the radar will automatically attempt to lock on what you're aiming at. As I understand it the aim point needs to be reasonably stable for 0.5 seconds for this to happen. Once locked on (the HUD will tell you by lighting up the "tailfin" on the velocity vector), if the target is moving and you follow it with the aim point, the computer will automatically track its motion, compute how much you need to lead it, and once you unsafe, the aim point will be compensated with that information so you can just point at the target and shoot. Nothing is shown on the radar screen or anything, you can't go head down in that kind of situation - the lock and the ranging are completely automated. The horizontal line with three vertical notches at the bottom of the HUD is a timing cue. It starts out long and shrinks towards the middle, and when it reaches the outer notches it's time to do your thing. You see it in action both when it's counting down to the pull-up point and when it's counting down to the appropriate moment to fire the rockets (you also get an extra cue in that case in the form of "wings" on the aiming point).

Yes, they also investigated the Draken. A test pilot was sent and got to fly both J 35A and the brand new J 35B prototype. The evaluation report is available online - relevant documents start on page 74, report from the test pilot starts on page 87. Later in the same file there's also a test report on the Mirage III by the same guy for easy comparison. I think what really clinched it for the Mirage III was the much better range (with drop tanks, mind) - Australia is, uh, kinda huge.

Well, I could've told you that ;V No translation of the AJ/AJS 37 flight manual exists. The aircraft never received enough foreign interest for that to happen. What may exist in English is the flight manual for some of the later JA 37 variants (the unclassified part definitely does exist, see the OP of the thread) but to my knowledge it's not declassified even in Swedish, and therein lies the rub, as they say. Christine-Charlotte is great though, always super helpful and she knows what's up. The Viggen Facebook group is by far the best resource on the aircraft anywhere on the internet, tons of old pilots and ground crew and generally knowledgeable dudes. Even Krister Karling (engineer who was head of the aerodynamics development) is a member and posts there sometimes.

Someone asked the same thing on reddit a while ago so I'll just quote my answer from then:

I know how to batch edit photos, yes, and I am aware tripods are a thing that exist. The problem is the national archives have a quite restrictive photo policy - you are allowed to take photographs, but only with a handheld camera with no extra equipment. Bringing any kind of camera mount or any type of artificial lightning of your own into the reading room is forbidden. It is possible a patterned background (like a checkerboard or something) to put the document page on could help with automating perspective correction by giving the algorithm an easily detectable pattern to lock onto, and I think that'd probably fly under the archivists' radar, but I'm really not interested in patching ScanTailor to actually use that kind of thing nor in writing my own solution from scratch. I could probably do it, but digital signals processing and machine vision really aren't my things so it'd be a hackjob. These days the "correct" solution probably involves a neural network and I really don't feel like training that, nor like writing the code to actually implement it.

120km.

Yes, but they're carried in pods that can only be mounted on the inner underwing pylons, so you can't carry certain weapons (mainly the rb 04 and rb 15 anti-ship missiles) and countermeasures at the same time. In reality, one or two aircraft in a flight of four would carry countermeasures. There's both a flare/chaff pod and an ECM jamming one.

Yes, it does.