DCS: AJS-37 Viggen Discussion

[Nerd1000]

Wouldn't GMTI require a doppler radar?

 

Yep.

 

Given that the Viggen carries anti-ship missiles, I expect that the primary task for this radar will be detection of surface vessels on water. It might also be capable of ground mapping.

[theOden]

Yep.

 

Given that the Viggen carries anti-ship missiles, I expect that the primary task for this radar will be detection of surface vessels on water. It might also be capable of ground mapping.

It very much is.

[Bacab]

GMTI in 1969? Let's not expect too much from these old radars.

Wasn't it upgraded with the AJS upgrade ?

[BravoYankee4]

Okay, so I took my garbage Swedish (and my wife is no help for the hard stuff inside a cockpit so I didn't even ask), and tried to give a general overview of the cockpit from the PDF posted a couple pages back. I made no efforts to hide where I wasn't sure, so expect question marks, notes, and mistakes.

 

But it's a start, and I've got it all as PSDs, so correct any mistakes I've got and we're golden.

 

I actually learned a ton about the plane in the process, and so you can probably see which pages I did first, and where I learned what things are.

 

Most of it seems to be right, but I have added and corrected some of it.

There are still some missing bits however, so anyone with more knowledge please step in.

My uncle was flying the Vampire and Lansen back in the days, so some generic swedish air force mumbo-jumbo can be explained by him. But out of context it can be really hard.

AJS37_LeftPanel.xls.pdf

[renhanxue]

Most of it seems to be right, but I have added and corrected some of it.

There are still some missing bits however, so anyone with more knowledge please step in.

My uncle was flying the Vampire and Lansen back in the days, so some generic swedish air force mumbo-jumbo can be explained by him. But out of context it can be really hard.

A lot of the dubious things requires reading the SFI (Särskild Förarinstruktion - the flight manual) to understand what is going on. It's split into four parts, and only part 1 is unclassified. I have most (but not all) of part 1 photographed - I ran out of time at the national archives last time I was there and had to skip some sections that I thought was uninteresting. I'll go back, probably on Saturday or next week and photo the entire thing and put it up as a PDF. I've requested to have parts 2-4 declassified but the handling of such requests can take months.

 

So to get to the point, here's what I've found in the SFI to clarify those points you've marked as unclear in your PDF:

 

1. Kanalväljare styrautomat - Selects which stick sensor channel to use. For use in case one of them fails. SFI chapter 1, section 12, page 28, paragraph 4.4.1.

 

 

7. Potentiometer LJUDSTYRKA UK-DÄMP - Volume control for the Sidewinders. Additionally, if you press and hold this, you get "100% UK-dämpning" - not sure what that means. Muting the radio? Dunno.

 

8. Tryckströmställare IR-RB FRAMSTEGN - In case of launching Sidewinders, Mavericks, BK 90 or rb 15 one by one, in order to proceed to the next weapon, you need to either make the weapons safe and then arm again, or press this button before you can launch the next weapon.

 

The entire weapons section of the SFI is really confusing, probably because there are two parallel systems, the old analog system from the original AJ 37 and a newer computerized MIL-STD-1553-based system that they added with the AJS 37 mod. See SFI chapter 1, section 25.

 

 

39. Strömställare ÅTERSTART - This is indeed manual engine restart. It's supposed to restart automatically, but if it doesn't you press and hold this for two seconds. SFI chapter 1, section 9, page 32 and 33.

 

 

46. Reglagebroms - Enables or disables autothrottle (fittingly named "AFK", automatisk fartkontroll). While it is enabled the physical throttle handle is locked in position, hence the name "reglagebroms" (roughly, "lever brake"). You can disable it either with a kill switch on the throttle handle, by pulling back the reglagebroms again, or by using violence to force the throttle to move (the SFI says 100 Newton of force is needed). SFI chapter 1, section 10.

 

 

By the way, the α 15.5° thing isn't just a warning light, it's also a toggle switch. When landing, you fly the final approach based on a target AoA, not on a target speed. Normally this target AoA is 12°, but pressing the button makes it 15.5° instead, in case you want to slam into the ground harder (recommended at road bases).

Edited December 10, 2015 by renhanxue

[scaflight]

...

 

You must spread some reputation around before giving it to renhanxue again.

[RaXha]

By the way, the α 15.5° thing isn't just a warning light, it's also a toggle switch. When landing, you fly the final approach based on a target AoA, not on a target speed. Normally this target AoA is 12°, but pressing the button makes it 15.5° instead, in case you want to slam into the ground harder (recommended at road bases).

 

Is this a common way to land an aircraft or is this something fairly unique to to the Viggen? :-)

[emg]

Wasn't it upgraded with the AJS upgrade ?

 

Not the radar, no. Basically it's a 1969/71 plane that was upgraded to carry modern weapons, and a new RWR.

 

Wouldn't GMTI require a doppler radar?

 

It's a fairly advanced radar mode. The Tornado attack radar doesn't have it.

When considering fighter-bombers only, AFAIK it didn't show up until the 80's with the Hornet radar.

Edited December 10, 2015 by emg

[renhanxue]

Is this a common way to land an aircraft or is this something fairly unique to to the Viggen? :-)

AFAIK it's common on carrier aircraft, not so much on anything else. Most aircraft tend to have instructions that say "maintain so and so airspeed and be at such and such altitude at so and so many miles from the threshold". In the ILS system there's a defined glideslope you're supposed to follow, but you don't do this by maintaining a specific angle of attack.

Edited December 10, 2015 by renhanxue

[RaXha]

AFAIK it's common on carrier aircraft, not so much on anything else. Most aircraft tend to have instructions that say "maintain so and so airspeed so and so many miles from the threshold".

 

Is suspected as much! This part was interesting to me. :-)

 

46. Reglagebroms - Enables or disables autothrottle (fittingly named "AFK", automatisk fartkontroll). While it is enabled the physical throttle handle is locked in position, hence the name "reglagebroms" (roughly, "lever brake"). You can disable it either with a kill switch on the throttle handle, by pulling back the reglagebroms again, or by using violence to force the throttle to move (the SFI says 100 Newton of force is needed). SFI chapter 1, section 10.

 

The AFK appears to be used mostly for landing if i understand the modes correctly:

 

Mode 1: Is engaged when the landing gear lever is set to IN, and sets a speed of 550km/h

Mode 2: Is engaged when the landing gear lever is set to OUT and sets a speed suitable for landing at 12° AoA, that would be a normal landing.

Mode 3: Is engaged when the landing gear lever is set to OUT and the switch α 15.5° is pressed. This sets a landing speed suitable for a 15.5° landing, as mentioned this would likely be a road base landing.

 

I noticed from the diagrams that the landing gear lever is not on the front panel, instead it's on the left side panel at the very rear, that to me appears quite unusual.

 

Btw, reading this manual gives me flashbacks to reading the SAAB 105 (SK-60) service manual in school. xD

Edited December 10, 2015 by RaXha

[BravoYankee4]

Is suspected as much! This part was interesting to me. :-)

 

 

 

The AFK appears to be used mostly for landing if i understand the modes correctly:

 

Mode 1: Is engaged when the landing gear lever is set to IN, and sets a speed of 550km/h

Mode 2: Is engaged when the landing gear lever is set to OUT and sets a speed suitable for landing at 12° AoA, that would be a normal landing.

Mode 3: Is engaged when the landing gear lever is set to OUT and the switch α 15.5° is pressed. This sets a landing speed suitable for a 15.5° landing, as mentioned this would likely be a road base landing.

 

I noticed from the diagrams that the landing gear lever is not on the front panel, instead it's on the left side panel at the very rear, that to me appears quite unusual.

 

Btw, reading this manual gives me flashbacks to reading the SAAB 105 (SK-60) service manual in school. xD

 

Found this:

"AFK avlastade flygföraren vid landning genom att reglera motorns dragkraft så att fart eller anfallsvinkel hålls konstant."

 

"The automatic throttle (speed) control helped the pilot at landing by setting the thrust so that either speed or aoa is constant"

[BravoYankee4]

A lot of the dubious things requires reading the SFI (Särskild Förarinstruktion - the flight manual) to understand what is going on. It's split into four parts, and only part 1 is unclassified. I have most (but not all) of part 1 photographed - I ran out of time at the national archives last time I was there and had to skip some sections that I thought was uninteresting. I'll go back, probably on Saturday or next week and photo the entire thing and put it up as a PDF. I've requested to have parts 2-4 declassified but the handling of such requests can take months.

 

So to get to the point, here's what I've found in the SFI to clarify those points you've marked as unclear in your PDF:

 

1. Kanalväljare styrautomat - Selects which stick sensor channel to use. For use in case one of them fails. SFI chapter 1, section 12, page 28, paragraph 4.4.1.

 

 

7. Potentiometer LJUDSTYRKA UK-DÄMP - Volume control for the Sidewinders. Additionally, if you press and hold this, you get "100% UK-dämpning" - not sure what that means. Muting the radio? Dunno.

 

8. Tryckströmställare IR-RB FRAMSTEGN - In case of launching Sidewinders, Mavericks, BK 90 or rb 15 one by one, in order to proceed to the next weapon, you need to either make the weapons safe and then arm again, or press this button before you can launch the next weapon.

 

The entire weapons section of the SFI is really confusing, probably because there are two parallel systems, the old analog system from the original AJ 37 and a newer computerized MIL-STD-1553-based system that they added with the AJS 37 mod. See SFI chapter 1, section 25.

 

 

39. Strömställare ÅTERSTART - This is indeed manual engine restart. It's supposed to restart automatically, but if it doesn't you press and hold this for two seconds. SFI chapter 1, section 9, page 32 and 33.

 

 

46. Reglagebroms - Enables or disables autothrottle (fittingly named "AFK", automatisk fartkontroll). While it is enabled the physical throttle handle is locked in position, hence the name "reglagebroms" (roughly, "lever brake"). You can disable it either with a kill switch on the throttle handle, by pulling back the reglagebroms again, or by using violence to force the throttle to move (the SFI says 100 Newton of force is needed). SFI chapter 1, section 10.

 

 

By the way, the α 15.5° thing isn't just a warning light, it's also a toggle switch. When landing, you fly the final approach based on a target AoA, not on a target speed. Normally this target AoA is 12°, but pressing the button makes it 15.5° instead, in case you want to slam into the ground harder (recommended at road bases).

 

 

Thanks! Most things makes some sense now.

 

When it comes to the sidewinder volume knob, I'm pretty sure it means that the UK/VHF radio is attenuated if volume is increased.

 

When it comes to AFK, is the TIPPVÄXEL switch (on the right side) related to this system?

[BravoYankee4]

Here is the right side panel, and once again - please help out with the gaps or persisting errors.

AJS37_RightPanel.xls.pdf

[RaXha]

When it comes to AFK, is the TIPPVÄXEL switch (on the right side) related to this system?

 

I'm not sure, but the word itself would translate to something like "pitch gear", so it could be related to the AFK or possibly the autopilot systems?

[BravoYankee4]

I'm not sure, but the word itself would translate to something like "pitch gear", so it could be related to the AFK or possibly the autopilot systems?

 

Hm... the options are "LANDN" or "AUT".

[jowl]

Here is the right side panel, and once again - please help out with the gaps or persisting errors.

 

Been spending many hours reading SFI (and getting som parts declassified) for a full size simulator we (http://www.swesim.se) are running.

 

SFI is not for the faint hearthed, spent loads of time trying to figure stuff out for implementation in our build.

 

2 is for the test system

8 is a holder for the g-suit/oxygen mask connector

15 KB is in general countermeassure

16 is defrost

 

*Tippväxel is the gearing of elevator v.s command stick. Got a landing regime (also for aileron) and for normal flight.

[RaXha]

Hm... the options are "LANDN" or "AUT".

 

Hmm, googling doesn't do much since i just find people trying to sell me trailers for trucks and tractors! :megalol:

[BravoYankee4]

A lot of the dubious things requires reading the SFI (Särskild Förarinstruktion - the flight manual) to understand what is going on.

 

I really need to find a copy of that manual :)

[RaXha]

Been spending many hours reading SFI (and getting som parts declassified) for a full size simulator we (http://www.swesim.se) are running.

 

SFI is not for the faint hearthed, spent loads of time trying to figure stuff out for implementation in our build.

 

2 is for the test system

8 is a holder for the g-suit/oxygen mask connector

15 KB is in general countermeassure

16 is defrost

 

*Tippväxel is the gearing of elevator v.s command stick. Got a landing regime (also for aileron) and for normal flight.

 

You guys have a lot of work ahead of you converting that to DCS. ;-)

[BravoYankee4]

Been spending many hours reading SFI (and getting som parts declassified) for a full size simulator we (www.swesim.se) are running.

 

SFI is not for the faint hearthed, spent loads of time trying to figure stuff out for implementation in our build.

 

2 is for the test system

8 is a holder for the g-suit/oxygen mask connector

15 KB is in general countermeassure

16 is defrost

 

*Tippväxel is the gearing of elevator v.s command stick. Got a landing regime (also for aileron) and for normal flight.

 

Thanks. Any idea how the nose gear and countermeasure system interacts here? can you elaborate?

 

By the way, I have been flying your Viggen simulator some years ago. Would love to do it again with a DCS Viggen module installed ;)

[Pikey]

Not disagreeing, just can you share your source, there's a book which was pasted into the wiki page saying that additionally the PS 37 was upgraded to a PS 371/A. We have a man at the museum scanning the documentation for it now and will confirm later when we have translated.

 

Looks like we got the radar documentation :D

 

Not the radar, no. Basically it's a 1969/71 plane that was upgraded to carry modern weapons, and a new RWR.

 

 

 

It's a fairly advanced radar mode. The Tornado attack radar doesn't have it.

When considering fighter-bombers only, AFAIK it didn't show up until the 80's with the Hornet radar.

[jowl]

Thanks. Any idea how the nose gear and countermeasure system interacts here? can you elaborate?

 

By the way, I have been flying your Viggen simulator some years ago. Would love to do it again with a DCS Viggen module installed ;)

 

 

Not 100% sure but guess that if weight on nose gear = KB inhibit. Same as reverser, no weight on nose gear = reverse inhibit.

 

Would love to convert to DCS - but all our interface is done in the fsx/p3d platform, not sure we want to redo that..

 

We are however a membership based non profit, so join and start lobbying for it :)

[Brisse]

Looks like we got the radar documentation :D

 

Wow! Good work. I've been looking for this but found very little. Most of the stuff out there on the internet is about the PS 46/A used in the JA, which is completely different.

[BravoYankee4]

Not 100% sure but guess that if weight on nose gear = KB inhibit. Same as reverser, no weight on nose gear = reverse inhibit.

 

Would love to convert to DCS - but all our interface is done in the fsx/p3d platform, not sure we want to redo that..

 

We are however a membership based non profit, so join and start lobbying for it :)

 

Yeah, that make sense - I.e. normally you probably don't want to pop some flare on the runway or during take off.

 

Well, if we ever get a DCS-BIOS support for a future Viggen module we have come a long way. There are already people on this forum building interfaces for real instruments also...

Yes, I have considered becoming a member for a long time... just did'nt happen yet.

[RaXha]

Wow! Good work. I've been looking for this but found very little. Most of the stuff out there on the internet is about the PS 46/A used in the JA, which is completely different.

 

Most of it is probably locked up in the Swedish national archives, It's "just" a question of getting it declassified which i understand can take a while, sometimes months, to get approved. :-)