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Saab 37 Viggen

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Re: Saab JA-37 Viggen Development

Postby Necolatis » Thu Jan 07, 2016 7:33 pm

Sounds like maybe its going too fast. This is what I found on it:

<max-detection-rng-nm type="int">28</max-detection-rng-nm>
<weight-launch-lbs>425</weight-launch-lbs>
<weight-warhead-lbs>87</weight-warhead-lbs>
<drag-area type="double">0.349</drag-area>

The thrust is classified, but its maximum speed should be mach 4 + the aircraft speed. So just increase the thrust until it reaches that speed around its maximum range.
Notice about maximum detection range, that 28 miles is under ideal conditions. Meaning the target is 28 miles out, but flying straight at you without big maneuvering. So maybe you should use around 20 miles for testing when it reaches mach 4 + aircraft speed.
And make sure its thrust duration is long enough to reach that. I am guessing 100-120 seconds, but you will have to experiment with that.
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Re: Saab JA-37 Viggen Development

Postby PINTO » Thu Jan 07, 2016 7:39 pm

For testing, I had a second FG instance running, flying straight using autopilot.

I was actually using the numbers from the F-15 that I took the missile model from, and the speed only topped out at around 3.5 mach before the thrusters cut out, but that wasn't near it's maximum range. I think I'll mess around with speed some more tonight (I didn't mess around with it too much when I was testing), I'll let you know if I have any success, thanks!
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Re: Saab JA-37 Viggen Development

Postby PINTO » Fri Jan 08, 2016 3:55 am

I messed with thrust, drag coefficient, and drag area, and had a ufo flying in front of me by ~15nm at the same speed and at the same heading I was. I fired a missile, without bringing the thrust-lbs above a value of 1,700, the lowest G's I could get it to pull was ~75.

The values I ended up using towards the end of testing were:

Code: Select all
                <rb71>
                    <sound-on-off type="bool">false</sound-on-off>
                    <sound-volume type="double">0.0</sound-volume>
                    <!-- RB-71 specs (Swedish version of Sparrow) -->
                    <max-detection-rng-nm type="int">25</max-detection-rng-nm>
                    <fov-deg type="int">25</fov-deg>
                    <detection-fov-deg type="int">140</detection-fov-deg>
                    <track-max-deg type="int">110</track-max-deg>
                    <max-g type="int">100</max-g>
                    <thrust-lbs type="double">1700</thrust-lbs>
                    <thrust-duration-sec type="int">100</thrust-duration-sec>
                    <weight-launch-lbs>425</weight-launch-lbs>
                    <weight-warhead-lbs>88</weight-warhead-lbs>
                    <drag-coeff type="double">0.080</drag-coeff>
                    <drag-area type="double">0.249</drag-area>
                </rb71>


Any ideas, or (and I hate to say this) is this good enough?
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Re: Saab JA-37 Viggen Development

Postby Johan G » Sun Jan 10, 2016 6:44 pm

Some data for the RB 24 (Sidewinder) can be found in the manual for the Sanders Smoke Technologies Smokewinder, which is modeled to have the same weight, CG and inertia and more or less the same dimensions (see p. 8 and 10).
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Re: Saab JA-37 Viggen Development

Postby Necolatis » Sun Jan 10, 2016 8:25 pm

Oh, that's nice, thanks. :)
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Re: Saab 37 Viggen Development

Postby Necolatis » Thu Jun 16, 2016 6:47 am

Thanks to Pinto, there is now an AJ-37 variant in the package and also now has less stutters and better graphics performance.

For full changelog, see https://raw.githubusercontent.com/NikolaiVChr/flightgear-saab-ja-37-viggen/master/Aircraft/JA37/changelog.txt.

Image

Image
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Re: Saab 37 Viggen Development

Postby PINTO » Thu Jun 16, 2016 7:15 am

A couple more shots.

Beauty shot:
Image

RB-15 about to impact an inert ship target (you can actually see the missile in this pic if you look close):
Image
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Re: Saab JA-37 Viggen Development

Postby vanosten » Mon Jun 27, 2016 6:49 pm

PINTO wrote in Tue Jan 05, 2016 8:55 am:Image


Is this large border for the front window really realistic? I love to fly the plane, but I find it strange that the pilot actually does not have a better view. I must admit that I do not have access to the real thing, but why would Viggen have a so much worse view for the pilot than e.g. the F-15?
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Re: Saab 37 Viggen Development

Postby PINTO » Mon Jun 27, 2016 9:38 pm

Disclaimer: I didn't do the 3d model of the Viggen - I've just been tweaking it.

Short answer: it's pretty close to the real thing, although it is slightly off.

Long answer: I matched up the 3D model and the blueprints from the AJ-37 manual, and the overhead bar in the cockpit is just a tad large on bottom (and a tad small on top), but the work in fixing it outweighs the benefit of having it fixed.

Image

Image

Rotated to better show size:
Image

EDIT: also the view really isn't that bad - the default FOV in the Viggen is set quite a bit bigger than other planes, so it's more noticeable. I hardly even notice it anymore.
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Re: Saab 37 Viggen Development

Postby Fritz » Mon Jun 27, 2016 9:51 pm

I think, the selected zoom factor and the 4:3 aspect ratio exaggerate the problem. On a wider screen we could see past the frame on both sides, and that's how a pilot in the real thing would see.
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Re: Saab 37 Viggen Development

Postby PINTO » Mon Jun 27, 2016 10:12 pm

16:9, 104* FOV.

Image
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Re: Saab 37 Viggen Development

Postby Fritz » Mon Jun 27, 2016 11:03 pm

Hmm... not the improvement I would have expected.
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Re: Saab 37 Viggen Development

Postby Necolatis » Tue Jun 28, 2016 3:15 am

I will change the zoom in next version, so the canopy is a little less in the view.

In this video you can also see in the cockpit shots that change, its minor, but its there:

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Re: Saab 37 Viggen Development

Postby Necolatis » Tue Jun 28, 2016 8:48 pm

The version 4.001 is now released on the hangar and in FGAddon.

Overview of changes:
===============
Many bugfixes.
Moved pilot eye view up 3 cm to better be able to instrument land.
Replaced the exterior fan sound and adjusted fly-by sounds and replaced the reheat part.
Reduced the time the flightrecorder records at full fidelity in half to help with people crashing FG after flying for 15 mins.
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Re: Saab 37 Viggen Development

Postby vanosten » Wed Jun 29, 2016 2:51 pm

I will have a trip to Ängelholms Flygmuseum in southern Sweden on Tuesday. I will see whether I can get allowed to take some pictures of the cockpit. If you need pictures of other parts of the plane, then please tell me - however I am not sure which version of Viggen is displayed.
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