DCS: AJS-37 Viggen Discussion

[grunf]

Well, they must download the Viggen so they are able to see it right? Maybe is coming the 9?

True, but who know what will they come up with. If the release would be before the 10th, I guess the Viggen spots would be open for anyone, not just the LNS guys. And the event announcement very much feels like a pre-release preview.

 

They might include the non flyable model of it in a regular patch before releasing the actual module though. :-) And then LNS can just somehow connect using their dev build. :-)

I'm hoping for non flyable model before release too, so I could at least shoot it down before flying it. :D

[diditopgun]

That would be so unfair for us.... I prefer to die rather than watch an event about a viggen I can't fly... ^^

[Pocket Sized]

Used to be like that. In later years it was modified to deploy when nosewheel touch down.

 

What good is a ram air turbine gonna do on the ground? :huh:

 

I did see some mechanical goodies (gauges) in the cavity it's stored in, is it opened to allow for easy access to those?

[il_corleone]

And the event announcement very much feels like a pre-release preview.

 

It´s LN :lol: Anything can happen

[QuiGon]

No pre-sale today :cry:

[RaXha]

What good is a ram air turbine gonna do on the ground? :huh:

 

I did see some mechanical goodies (gauges) in the cavity it's stored in, is it opened to allow for easy access to those?

 

It can be manually deployed in the air to. xD But during landing i suppose it could be used to proved emergency hydraulic power to the brakes maybe? I realise it wont do much good at low speeds. :P

[Goblin]

What good is a ram air turbine gonna do on the ground?

 

It will of course deploy if needed, in the air.

On the ground it must be open in order to reveal some refill points for hydraulic, the radar and O2. It also reveals the starter motor fire light and extinguisher nozzle, which is needed for startup.

 

The point is rather that it can't close, and chop somebodys hand off, when on the ground.

[Hook47]

Hey Fellas-

 

Just wanted to clear up any confusion about the Grudge Match Round 3 and the inclusion of the Viggen- LNS approached us at the end of round 2 with this epic idea, and it is intended to give our audience and Viggen fans a preview of the aircraft in a combat environment. It is in no way representative of the Modules release date (as badly as we all want it!) as the contestants of the match will be set up with the means to see the Viggen in a special arrangement. I just didn't want anyone to read it as anything official from the DCS World or LNS standpoint regarding content release.

 

Thanks and I hope to see you guys tune in! This will be like a trailer.... But in real time :)

[BravoYankee4]

It can be manually deployed in the air to. xD But during landing i suppose it could be used to proved emergency hydraulic power to the brakes maybe? I realise it wont do much good at low speeds. :P

 

Speaking of easy access etc. Keep in mind that the Viggen plattform was serviced by a conspript ground crew team with just a few months of training. A pretty unique setup as far as I know.

And they where really good at it with short turn arounds keeping the birds on the ground for a very short time.

[grunf]

Hey Fellas-

 

Just wanted to clear up any confusion about the Grudge Match Round 3 and the inclusion of the Viggen- LNS approached us at the end of round 2 with this epic idea, and it is intended to give our audience and Viggen fans a preview of the aircraft in a combat environment. It is in no way representative of the Modules release date (as badly as we all want it!) as the contestants of the match will be set up with the means to see the Viggen in a special arrangement. I just didn't want anyone to read it as anything official from the DCS World or LNS standpoint regarding content release.

 

Thanks and I hope to see you guys tune in! This will be like a trailer.... But in real time :)

Thanks for clearing it up! There was no confusion, maybe just our imagination running wild, which is nothing unusual around here :). Anyway thank you, the LNS and everyone involved with the event. I'll surely tune in and enjoy it. :thumbup:

[Snail]

Speaking of easy access etc. Keep in mind that the Viggen plattform was serviced by a conspript ground crew team with just a few months of training. A pretty unique setup as far as I know.

And they where really good at it with short turn arounds keeping the birds on the ground for a very short time.

 

Yep, a group of conscripts and one officer, rearming and refueling the jet in 10 minutes or so.

 

There was an exercise where they managed to pull out 11 sorties in one day for the same aircraft.

[Goblin]

Yep, a group of conscripts and one officer, rearming and refueling the jet in 10 minutes or so.

 

We did a simulated road-base rearm/refuel with a foreign aviation journalist present. He refused to believe we were concripts, serving the jet. "In my country, conscripts would be thrown in jail if they got this close to the aircraft". :-D

[Snail]

We did a simulated road-base rearm/refuel with a foreign aviation journalist present. He refused to believe we were concripts, serving the jet. "In my country, conscripts would be thrown in jail if they got this close to the aircraft". :-D

 

Trust pays off, just like thrust by the way ;-)

[shaggy]

[mambo]

[QuiGon]

Quick question: Can the radar lock onto ground targets (e.g. ships)?

[Pocket Sized]

I've heard that the Viggen becomes unstable in the transonic region, (to the point of there being a dedicated warning light) can anyone elaborate on this?

 

Seeing as we're probably going to spend a lot of time at low altitude + full mil, this kinda concerns me :(

[BlackLion213]

I've heard that the Viggen becomes unstable in the transonic region, (to the point of there being a dedicated warning light) can anyone elaborate on this?

 

Seeing as we're probably going to spend a lot of time at low altitude + full mil, this kinda concerns me :(

 

I'm not that well informed, but judging from yesterdays Grudge Match where Viggens were seen reaching ~797 KIAS on the deck (with rockets loaded)!!....I'm pretty sure that it will be flyable straight and level at very high speeds.

 

However, the Viggen gameplay video does show some less than elegant pitch response at transonic speeds (section while firing rockets). My guess is that it will fly beautifully straight and level, but fight back a bit as you load up the airframe in the transonic region.

 

Just I guess from what I've seen thus far.

 

-Nick

[renhanxue]

It's not unstable in the transonic region, but there are trim changes and that's what the light is calling your attention to. The SFI (del 2 kap II) says:

 

24.2 Characteristics in the transonic region and at high Mach numbers

 

The aircraft has good handling characteristics at high Mach numbers.

 

[...]

 

With the autopilot's standard mode SPAK active, a weak nose down trim change appears at M = 0.95, but it becomes negligible at M ≈ 1.03. At high Mach (depending on altitude), there is a moderate nose down trim change that is caused by exceeding the series trim authority.

 

Elevon authority is somewhat reduced at supersonic seeds. Stick movements hence become somewhat larger, which leads to increased stick forces.

The issues start if the autopilot has failed somehow so you don't have the oscillation dampening and trim help etc that SPAK mode provides. In the fallback mode (GSA) the aircraft starts having weak pitch down tendencies at M ≈ 0.85, changing to pitch up at M ≈ 0.95, and then changing back to pitch down at M > 1.03 and increasing in force as M increases.

 

Additionally:

24.3 High alpha

[...]

24.3.2 Load factor > 1

[...]

Drag increases heavily as alpha rises. The aircraft therefore loses speed rapidly in turns with high load factor, if the speed loss is not offset by increased throttle and/or a reduction in altitude. The aircraft is capable of very tight turns, but these require high throttle (lit AB in most cases) in order to avoid losing speed rapidly. When rapidly applying large pitch inputs, there is a risk of load factor overshoot resulting in exceeding maximum permitted load factor. The pilot should therefore avoid harsh stick movements that give rapid load factor increases. In order to avoid quick retardation when flying with high load factor, the pilot should apply throttle increase before the stick command, so that the power comes at the same time as the load factor increase.

 

Light buffeting starts appearing at ɑ 4-5°. The buffeting grows somewhat in strength with increasing alpha, and is more or less constant at ɑ > 12°. The buffeting level does not limit maneuverability or the ability to aim. At supersonic speeds there is no buffeting at any load factor.

 

In turns with quick retardation from M = 1.0 down to M ≈ 0.9 pitch-up tendencies appear, the strength of which depend on the aircraft's load factor when entering the transonic region. The reason for this is the normal change of the longitudinal stability and control surface authority in this speed regime. External loads only have a moderate effect on these characteristics. Care shall be taken when retarding from M ≈ 1.0 to M ≈ 0.9 so no unacceptable increases of load factor and/or alpha are encountered.

 

 

e: the aerodynamics compendium has more to say about this though, namely that certain types of underwing loads (ARAK and countermeasure pods mentioned) make the available pitch authority quite low in transonic and supersonic regimes.

Edited December 11, 2016 by renhanxue

[probad]

I've heard that the Viggen becomes unstable in the transonic region, (to the point of there being a dedicated warning light) can anyone elaborate on this?

 

Seeing as we're probably going to spend a lot of time at low altitude + full mil, this kinda concerns me :(

 

who are you hearing these things from? that's what concerns me.

[Goblin]

who are you hearing these things from? that's what concerns me.

 

Cobra said so himself, in a post here, somewhere :)

[probad]

i dont recall cobra's description of it to be too alarming, which was why i was curious to know if he heard it from somewhere else.

[Cobra847]

Mach tuck is quite noticeable, and the aircraft does vibrate in the transonic region.

 

Additionally, the control scheme changes significantly between sub-sonic and supersonic flight regimes, so there is a noticeably "sharp" change in control deflection.

[Goblin]

The Viggen had pitch stability problems in the transpnic speed region. This was partly solved by area ruling the fuselage by adding a hump on the fuselage spine.

 

I wrote about it in the "Can you make it over the hump" thread... :)

 

https://forums.eagle.ru/showpost.php?p=2811750&postcount=54

 

Come to think of it, I don't believe we ever got an answer to the question in that thread... ;)

[Hummingbird]

Mach tuck is quite noticeable, and the aircraft does vibrate in the transonic region.

 

Additionally, the control scheme changes significantly between sub-sonic and supersonic flight regimes, so there is a noticeably "sharp" change in control deflection.

 

The bobbing up and down in pitch as if bouncing on a spring, that I've noticed in a couple of videos now, looks abit weird though.