DCS: AJS-37 Viggen Discussion

[Hook47]

Not to derail this fine discussion, but since Raxha let the cat out of the bag, I invite all my fellow Viggen fans to consider trying their hand at winning an awesome prize next month! :) LNS, you are awesome!

 

Back to our regularly scheduled Viggen Discussion :)

[Rangi]

Not to derail this fine discussion, but since Raxha let the cat out of the bag, I invite all my fellow Viggen fans to consider trying their hand at winning an awesome prize next month! :) LNS, you are awesome!

 

Back to our regularly scheduled Viggen Discussion :)

 

 

Which cat, what bag?

[drPhibes]

Here are some Viggen related pics from the Swedish military archives: http://www.svd.se/unika-bilder-viggen-piloternas-fotokrig-med-sovjet#

[Snowman]

Here are some Viggen related pics from the Swedish military archives: http://www.svd.se/unika-bilder-viggen-piloternas-fotokrig-med-sovjet#

 

That article also tells some stuff that I didn't know before.

One main thing that cought my attention is that apperantly the Swedish AirForce was pretty aggressive in close monitoring off the Russian planes. The Swedish pilots thought that the Russians was practicing attacks on Sweden but according to the Russians they were actually practicing against figured NATO targets.

Today compared to then its the Russians that are aggressive in close monitoring the Swedish planes. There have been several incidents when the Russian planes have been coming way to close. Even to civilian traffic over the Baltic Sea, specially the southern part.

[microvax]

 

Have a meme I quickly threw together, to illustrate the style and feel killing anything with the rb05 will result in.:lol:

[Hook47]

Like a sir, Microvax, like a sir

[renhanxue]

This popped up in my feed today:

 

[ame]https://www.youtube.com/watch?v=KEyY2Q37sYQ[/ame]

 

Audio is pretty cheesy but that's pilots for you.

[Rammit]

Audio is pretty cheesy but that's pilots for you.

 

Cheesy? The first track is some of the finest music ever to be composed by man

 

EDIT: For cheesy I raise you to the start of this video..

 

[ame]

[/ame] Edited August 21, 2016 by Rammit

[mattebubben]

The Viggen is such a sexy beast =).

 

And i cant wait to do some proper real low flying =).

[amb]

I've always wondered about one thing, I'm not sure I should bother anyone with it, but maybe someone is bored and know a lot about aerodynamics...

 

So the thing is: Why is it that the Viggen seems to have such a large wing surface area, yet it doesn't seem to turn much better (any better?) than for example a F-4 Phantom which has sort of small-ish wings - or more regular sized wings one might say.

 

I know the wing area isn't the only thing determining lift, but I've just always wondered why they decided to design the Viggen's wings that way, with such large area. My best guess is that it has something to do with providing lots of lift at slow speeds to shorten take-offs?

 

I don't really have any idea what I'm talking about now, but from my layman's perspective I guess it makes sense that a large wing area with a low camber would be able to give a lot of lift at slow speeds if the alpha is high enough, while also providing relatively little drag at high speeds. Is that what's going on here or am I way off?

[microvax]

I've always wondered about one thing, I'm not sure I should bother anyone with it, but maybe someone is bored and know a lot about aerodynamics...

 

So the thing is: Why is it that the Viggen seems to have such a large wing surface area, yet it doesn't seem to turn much better (any better?) than for example a F-4 Phantom which has sort of small-ish wings - or more regular sized wings one might say.

 

I know the wing area isn't the only thing determining lift, but I've just always wondered why they decided to design the Viggen's wings that way, with such large area. My best guess is that it has something to do with providing lots of lift at slow speeds to shorten take-offs?

 

I don't really have any idea what I'm talking about now, but from my layman's perspective I guess it makes sense that a large wing area with a low camber would be able to give a lot of lift at slow speeds if the alpha is high enough, while also providing relatively little drag at high speeds. Is that what's going on here or am I way off?

 

About the right direction, there is a public NASA paper on the Viggen aerodynamics if you want to get in depth.

 

And honestly I expect it to turn better then an f4 by miles. The biggest problem here is probably G limit [7,5 afaik] and the rm8a, which will suffer from compressor stalls at high aoa [over 18degrees afaik.]. Aerodynamically you could probably get more out of the design, but well, there was no need so they didnt go for that.

[robban75]

I don't expect the Viggen to be a stellar turner, at least not in terms of sustained turn rates. However, a friend of the family used to fly the JA 37,(and J 35 before that). He told me he had met F-4's several times over the Baltic sea and that he had no problem outturning them with the Viggen, . In 2004 I had the opportunity to talk to a german Tornado pilot. I asked him if he thought the Tornado and Viggen were comparable, and he swiftly responded, no no! The Viggen is much more agile. :)

 

My expectations of Viggen is that it is fun and easy to fly, and with excellent acceleration and good climb rates. :pilotfly:

[RagnarDa]

I've always wondered about one thing, I'm not sure I should bother anyone with it, but maybe someone is bored and know a lot about aerodynamics...

 

So the thing is: Why is it that the Viggen seems to have such a large wing surface area, yet it doesn't seem to turn much better (any better?) than for example a F-4 Phantom which has sort of small-ish wings - or more regular sized wings one might say.

 

I know the wing area isn't the only thing determining lift, but I've just always wondered why they decided to design the Viggen's wings that way, with such large area. My best guess is that it has something to do with providing lots of lift at slow speeds to shorten take-offs?

 

I don't really have any idea what I'm talking about now, but from my layman's perspective I guess it makes sense that a large wing area with a low camber would be able to give a lot of lift at slow speeds if the alpha is high enough, while also providing relatively little drag at high speeds. Is that what's going on here or am I way off?

 

 

 

 

One important difference between Viggen and other planes like F-4 and F-16 is aspect ratio: the ratio of the length vs width of the wing.

 

Hold your hand flat with the thumb facing your eyes. Imaging what you see is what the wind racing against the wing is "seeing" and interacting with. If you angle your hand so your thumb points to the ceiling you will see a little more of your hand and by analogy the wind will interact with. This represent a high-aspect wing. If you on the other hand hold your hand flat and so the tips of your fingers are pointing towards your eye you will see less of your hand than in the first case, and therefore the wind which is flowing on the wing will have less wing to generate lift with. If you angle your hand now so the tips of your hand is pointing towards the ceiling your will again see most of your hand-wing. This represent a low aspect wing. A low-aspect wing with short wings are good if you want to cram as much wing-area you can behind the shock-wave that is generated by the nose during supersonic flight. A high-aspect ratio wing on the other hand don't need to be angled so much (alpha or angle of attack) to expose a large part of the wing and is therefore more efficient (on for example sail-planes) because if you need to angle your wing a lot to generate the needed lift more of the lift is pointed in the opposite direction of your travel direction (now called "induced drag").

 

So compared to a high-aspect fighter like the F-16 the Viggen can generate the same lift or more in a turn = acceleration into another direction or G's. But, it can't do it without loosing a lot of its speed in the process because it has to hold a higher alpha. This problem is also apparent when for example landing as it is difficult to maintain a specific airspeed, hence the implementation of the landing-autothrust called AFK in the Viggen.

[boopidoo]

The Viggen actually lands with low alpha which was one of its design criterion. AFAIK the auto-throttle was there to make landing easier but I don't think it was really that difficult without it. I landed the Viggen (JA37 simulator) on my first try when I was 15 years old (a good indication that it's an easy machine to handle, not that I was a wonder kid). I can't remember if I used auto-throttle but I don't think I did.

Edited August 23, 2016 by boopidoo

[Skjold]

The Viggen actually lands with low alpha which was one of its design criterion. AFAIK the auto-throttle was there to make landing easier but I don't think it was really that difficult without it. I landed the Viggen (JA37 simulator) on my first try when I was 15 years old (a good indication that it's an easy machine to handle, not that I was a wonder kid). I can't remember if I used auto-throttle but I don't think I did.

 

Not to bash your performance or anything but a lot of the simulators in museums etc use an extremly simple flight model that wouldn't represent the difficulty of landing it properly.

[RagnarDa]

DCS: AJS-37 Viggen Discussion

 

The Viggen actually lands with low alpha which was one of its design criterion. AFAIK the auto-throttle was there to make landing easier but I don't think it was really that difficult without it. I landed the Viggen (JA37 simulator) on my first try when I was 15 years old (a good indication that it's an easy machine to handle, not that I was a wonder kid). I can't remember if I used auto-throttle but I don't think I did.

 

 

 

I can't remember reading that low-alpha landings was a design criterion for Viggen? I might misremember or missed it but all I can remember reading is the short-field requirements (<500m), and that the design should be mechanically simple (ruling out variable wings), "good maneuverability" and then nothing else. Don't know what is considered low alpha while landing and if 12 or 15,5 degrees qualify as low or high but a short Google-search for comparison gives the F-4 at about 10 degrees and the F-18 at 8 degrees when landing at a carrier.

 

Since this has come up before I think it's important to get the right expectation of how the Viggen flies and understand the trade-off of the severe induced drag that is inherent in its design. I suggest reading more on Wikipedia on the topics of induced drag or aspect ratio or searching for "Aerodynamics of the Viggen 37 aircraft". If nothing else you might want to read this interview with a Viggen pilot: http://www.warbirdsnews.com/warbird-articles/swedish-air-force-historic-flight-cockpit.html

[microvax]

I can't remember reading that low-alpha landings was a design criterion for Viggen? I might misremember or missed it but all I can remember reading is the short-field requirements (<500m), and that the design should be mechanically simple (ruling out variable wings), "good maneuverability" and then nothing else. Don't know what is considered low alpha while landing and if 12 or 15,5 degrees qualify as low or high but a short Google-search for comparison gives the F-4 at about 10 degrees and the F-18 at 8 degrees when landing at a carrier.

 

Since this has come up before I think it's important to get the right expectation of how the Viggen flies and understand the trade-off of the severe induced drag that is inherent in its design. I suggest reading more on Wikipedia on the topics of induced drag or aspect ratio or searching for "Aerodynamics of the Viggen 37 aircraft". If nothing else you might want to read this interview with a Viggen pilot: http://www.warbirdsnews.com/warbird-articles/swedish-air-force-historic-flight-cockpit.html

 

 

I would say Viggen qualifies for high AOA for an plane, but normal AOA for something delta wingish.

 

 

BTW, is there any chance we can get the Viggen Manual 1-2 weeks earlier then the release ?

Like they did it with the f5e. That way we could blow up the entire russian invasion fleet on day 1 :joystick::pilotfly: :D

Edited August 23, 2016 by microvax

[Pilum]

I've always wondered about one thing, I'm not sure I should bother anyone with it, but maybe someone is bored and know a lot about aerodynamics...

 

So the thing is: Why is it that the Viggen seems to have such a large wing surface area, yet it doesn't seem to turn much better (any better?) than for example a F-4 Phantom which has sort of small-ish wings - or more regular sized wings one might say.

 

I know the wing area isn't the only thing determining lift, but I've just always wondered why they decided to design the Viggen's wings that way, with such large area. My best guess is that it has something to do with providing lots of lift at slow speeds to shorten take-offs?

 

I don't really have any idea what I'm talking about now, but from my layman's perspective I guess it makes sense that a large wing area with a low camber would be able to give a lot of lift at slow speeds if the alpha is high enough, while also providing relatively little drag at high speeds. Is that what's going on here or am I way off?

 

There was actually a discussion about the Viggen turn rate earlier in this thread:

 

http://forums.eagle.ru/showpost.php?p=2769114&postcount=1781

 

The turn rate discussion goes on for some pages after that including some nice climb and acceleration charts on page 182. :)

[Cobra847]

 

BTW, is there any chance we can get the Viggen Manual 1-2 weeks earlier then the release ?

Like they did it with the f5e. That way we could blow up the entire russian invasion fleet on day 1 :joystick::pilotfly: :D

 

This is likely, but you'll also have many "walkthrough" videos and streams to learn from which will be released quickly one after another prior to release.

[Darkbrotherhood7]

This is likely, but you'll also have many "walkthrough" videos and streams to learn from which will be released quickly one after another prior to release.

 

Thanks, glad to hear that. :)

[QuiGon]

This is likely, but you'll also have many "walkthrough" videos and streams to learn from which will be released quickly one after another prior to release.

 

When? :D

[BravoYankee4]

When? :D

 

Two weeks I assume ;)

[TomCatMucDe]

When? :D

 

"get ready to be bombarded by videos and marketing material" that was a year ago. Wait for another one :P

 

kidding. :pilotfly:

[microvax]

This is likely, but you'll also have many "walkthrough" videos and streams to learn from which will be released quickly one after another prior to release.

 

*glowing eyes* The hype will be real. :lol:

 

Thx for the info though ! :)

 

Literally cant wait, lectures for uni start in early to mid october. xD

[Pocket Sized]

What options are there for targeting the glide bombs?

 

In other words, do we have to type coordinates into the INS or are there alternate methods? (i.e. using the HUD to designate a target like in the A-10/Mirage)