renhanxue

I have no idea why it behaves like that. It looks really weird in the graphs. Maybe it's the intakes that are the limiting factor?

I'm not so sure it's unrealistic. These graphs are for a clean JA 37, which actually has a more powerful engine: As you can see, the real aircraft does hit a "wall" around Mach 1.8 at 12 km MSL. Mach 2.0 in level flight is only achievable on a cold day, and only at a narrow range of altitudes around 11 km MSL.

BFASK = bombfallskärm, drag chutes for the 120kg bombs. Fask is the ugliest abbreviation in the entire Air Force.

Oh, that one. It's an assessment from first principles by someone with no access to any actual aerodynamic data. I dunno why you'd trust that over the actual declassified flight manuals for the real aircraft.

That sounds way too high. There's really not much difference between RM8A and RM8B when it comes to thrust, and what difference there is is mostly at dry thrust. Both of them make around 165 kN at Mach 1.1 at sea level at max zone 3. There's a thrust diagram for the RM8A in the OP, and for the RM8B, see SFI JA 37 del 4, page 79.

Operator's station from a PS-08 radar installation (PS-08 was the Swedish designation for the Decca Type 80 long range air search radar purchased in the late 1950's). I think this is the oldest intercept controller station that supported the data link; it was installed directly at the radar site instead of in an air defense central (Lfc, "luftförsvarscentral") or sector intercept control center (rrgc, "radargruppcentral"). In the center there's a big orange PPI (of course) - the data link control panel is to the left of the PPI, in the top part of the console. There's two sets of controls so the intercept controller working the station can send orders to two aircraft (or even groups of aircraft) at once. For each of the two data link channels: at the top there's three dials, one with the letters of the alphabet and two numeric ones. These are for addressing - you set the dials to the address configured on the receiver in the aircraft and the data link packets will be addressed to that (or those) aircraft. Just under the dials there's a small button labeled "FLYGPL" - it can be set to either J 35 (older message format) or JA 37 (newer message format) depending on which aircraft you're trying to talk to. Then there's 20 red buttons that are unlabeled on this console - these let you send one of 20 of pre-arranged informational messages to the aircraft, such as "expect jamming", "caution enemy fighters", "RTB", and so on. These messages were later extended so there were 30 of them, and the buttons had different meanings for J 35 and JA 37 and they also changed over time, so there was a reversible label template that you put on top of them to remember which one was which, like so (on a different console): This one's labeled for JA 37 and has two "priority" modes - red texts are presumably what the message means when sent in high priority mode. If you flip it over there's J 35 message labels on the other side. Example messages on this one are f.ex. 03 - low priority "enemy fighters", high priority "target (has) escort", 10 - low priority "idle", high priority "fire at will". Full console from a more modern rrgc/F installation - the one with the message buttons in close-up above. Data link message buttons in the lower left, with the label template flipped over to the J 35 side. On this one with its fancy-schmancy digital computer, you set the aircraft type etc via keyboard shortcuts instead.

The Swedish Air Force data link system (it doesn't have a name, the literature only refers to it as "Flygvapnets styrdatasystem") maintained the same 103-bit packet format and general infrastructure for over 40 years - the signal multiplexers in the ground stations stayed the same from installation in the early 60's to retirement in the early 2000's. The JA 37 fighter to fighter link also used the same packet format and transmission tech, but I believe on other frequencies. An early 1960's Stril 60 ground installation could talk to an early 80's JA 37 as if it was a J 35B and it'd work, but in the early 80's the ground installations were upgraded to be able to send a variant of the data link packet that modified the structure slightly and used some previously reserved bits to send an identically structured message but with different meaning and a bit more data. In the Draken days, the ground installation would calculate the intercept vector based on the intercepting aircraft's radar-measured position and transmit the target's altitude as well as its bearing and distance relative to the intercepting aircraft. For the JA 37 however you could also choose to transmit the target's absolute position and altitude instead and let the onboard computer do the intercept vector calculations instead, for higher precision. On upgraded ground installations there were a few switches that controlled what to send, and since the general packet structure and addressing etc was compatible, messages for JA 37's and J 35's could share the same cabling, multiplexers, transmitters, frequencies etc etc. I have a few photos of an operator's station from the missile museum in Arboga somewhere, I'll see if I can dig them up. This report from FHT has a ton of detail, but it's from 2005 and mainly centered on the early days. The extensions for the then recently retired JA 37 are discussed only briefly.

While the data link was one of the major new features of Stril 60, it was not required for air combat control. Also, “system 37” was not multi-role - the various aircraft variants had completely different requirements. The AJ(S) 37 never had a data link receiver because it wasn’t an air defense aircraft. GCI with plain old talk radio was sufficient for its very modest air to air capability.

The article essentially says that some information about RBS 15 was released to the public as declassified even though it should have been kept secret. The archivist that released it was fined for "carelessness in handling of classified information". The person who requested and published the information has not been accused of any wrongdoing, as they had no way of knowing that the decision to declassify was done by mistake.

I don't disagree, and going supersonic at low altitude was not really standard procedure or exercised often in the Viggen as far as I know. Low altitude flying at high subsonic speeds over fairly long distances was common though. Just getting your type rating on the Viggen as a fresh cadet right out of flight school (before you started tactical training at all) required a couple of exercises in low altitude navigation flights with a flight instructor in the back seat. First a few lessons at economical speed (roughly 550km/h IAS), but also at least one stretch at M 0.8 at 50m AGL.

The 500 kg mine bomb was an anti-ship weapon. The 120kg m/71 bombs are mainly used for fragmentation effect over a larger area. A capital M in the m/year designation indicates that the object in question belongs to the navy, by the way. The more you know! :V

Agreed. It should be hard to ignite it at high altitude, but if you have it running it should keep going pretty well and restarting it at lower altitude shouldn't be a problem.

Not going to get around to PDF-ifying this tonight, but here's some quality reading in JPEG format for y'all. Enjoy 26-bit fixed point arithmetic - there's a list of instructions ("microprograms") with latencies and everything listed so you can start writing your own CK 37 programs.

Right now, at the national military archives library, in paper form... I didn’t get around to visiting last week but I’m intending to hit it up tonight.

It's actually significantly more restrictive in reality than it is in DCS. In reality, the computer only supports input of longitudes greater than 0° but less than 40°, and latitudes larger than 40° but less than 90°. Roughly speaking, it supports longitudes from Greenwich in the west to Yaroslavl in the east, and latitudes from the North Pole to Madrid in the south. One upside of this is that you can enter latitude and longitude in any order on the real aircraft - the two coordinates have different numerical ranges and the computer can automatically detect which is which. This was hardcoded as far as I am aware, and not only on the AJ 37 - it was the same on all the other Viggen variants, including the JA 37 all the way up to the JA 37C, despite its much more modern computer. I guess the very last Viggen variant - the short-lived JA 37Di, which was specifically intended for international interoperability - might have changed it though, but I'm not actually sure. I guess if they had ever exported the Viggen they would've needed to fix this, but as it was, no Viggen ever left Europe and it was never an issue. Sweden did not have any territorial expansionist or power projection intentions and the aircraft was plenty capable in its intended area of operations. At air shows in the UK or in France I guess they relied on paper maps. Here's the relevant section from the JA 37C's English flight manual (note the references to the data link system which didn't exist on the AJ 37 - an air combat controller on the ground can upload waypoints directly to your aircraft, among other things):

My impression is that it's generally regarded as very good. It's not perfect though, of course - there are a few minor issues remaining with induced drag being slightly higher than it should be and dry thrust being slightly weaker than it should be, but they are being worked on as far as I know. In most scenarios though the aircraft performance is very close to what the flight manual for the real thing says it should be like. The modelling is fantastically detailed by the way; things like the hydromechanical fuel flow regulator in the engine and the onboard computer's program cycle length are simulated. The flight manual for the real aircraft is generally works better as a reference point than Leatherneck's own manual, at least if you read Swedish... A few threads: https://forums.eagle.ru/showthread.php?t=181787 (an actual Viggen pilot chiming in) https://forums.eagle.ru/showthread.php?t=182488 https://forums.eagle.ru/showthread.php?t=184532 Some of these issues may have been fixed or at least partially addressed since.

I have no idea! Which facebook group was that?

Well, yes... unfortunately for the international audience.

Reviving this thread to state that I still haven't heard back on the 1984 tactics manual. A late-70's fighter tactics manual with an update package from as late as 1982 has popped up in the library catalog though so I guess I might take a stab at that one of these days. In other news though, another interesting thing that popped up as "new" in the library catalog recently is a complete manual for the CK 37, dated 1971, with seven main parts (plus a spare parts catalogue): 1. Functionality 2. Devices 3. Circuit diagrams 4. Connections list CEL 5. Connections list CEM 6. Connections list IU (presumably "IU" stands for "in/ut", or input/output) 7. Circuit boards and list of jumpers/switches I myself am quite interested in that one, especially if it's actually understandable to a modern software engineer like myself. Is anyone else a bad enough nerd...?

The only two paint schemes used in line service were "M90" (not actually m/90) and bare metal with black radome, as far as I know. Some SF 37's (and maybe SH 37's/SK 37's as well? unsure) were painted in the Gripen-style two-tone fighter grey late in their career, but I don't know if that was ever done to AJ 37's. There might have been a few early AJ 37's painted olive drab (like the Lansen) for a short time as well, but I'm unsure on that one too.

No, that sounds correct. The distance economy numbers for 9000 and 10000 meters are only relevant to a clean aircraft. As per the SFI for the real aircraft, if you have a drop tank you can't maintain level flight at those altitudes without the afterburner. Depending on the loadout, best distance economy is usually somewhere around 7 km MSL. If you want the details, go look at SFI fpl AJ 37 del 3, in particular the flight envelope graphs under the heading "planflykt" around page 80 in the PDF. There's altitude vs top speed graphs on the following pages as well.

In reality the peacetime safety regulations called for no lower than 10 meters AGL when over water and 20 meters over land. In war? You bet they'd be going as low as they possibly could. Have a pair of videos (none of them AJ 37, but enjoyable nonetheless): https://www.youtube.com/watch?v=KEyY2Q37sYQ Photo recon Viggen, in-flight footage starts at 03:00 (and make sure you stay until at least 03:45). Makes it blindingly obvious why these planes are painted green rather than grey. You kids with your clean-shaven faces and fancy standoff anti-ship weapons don't know how good you have it. Men made of the Right Stuff have proper facial hair and 250kg anti-ship bombs as a backup, and they fly appropriately low. Watch the entire thing, there's a lot of really awesome and unique footage in there.

What are you using as the firing cue? The sight isn’t CCIP, it’s only correct when the “wings” on the flight path marker show up. See https://forums.eagle.ru/showpost.php?p=3034538&postcount=31

Yeah, the texture is from a JA 37 cockpit at the moment.

Low altitudes were typically not specified in meters in the Swedish Air Force flight plans of this period. It was typically stated as “lowest altitude” which in practice meant “as low as you reasonably can”, with certain peacetime restrictions. It was up to the flight lead to decide in flight exactly how low he wanted to go, keeping in mind the threat level, terrain etc.