Special Hobby SAAB AJ 37 Viggen

[JonMW]

This GB is a good excuse to build another Viggen or Thunderbolt. As I've already done three Tarangus JA kits I thought it was time to do a AJ version. I've also got some aftermarket parts for it, I might have gone a bit too far with the aftermarket stuff to be fair but it's easy when you like the subject.

The kit















And some extras

















With only six weeks left of the GB it will be a bit of a push to get it done but it should be doable.

[TommyKillander]

Holy Sheet, buddy

It will take 6 weeks just to sort out all that aftermarket and to figure out where to put it

Best of luck with the build - there's no need for an excuse to build a Viggen


Tommy

[Paul]

Splinter cam, awesome, look forward to seeing this come together Jon

[DrSprue]

Wow what an amazing collection of aftermarket stuff!! I think the most I ever paid for some of those additions was the kit by itself alone! So cool, very neat kit as well!

[Tomcat64]

Really looking forward to watching you work your magic with this one Jon

[JonMW]

The Viggen has a rat, as in a ram air turbine, this is a small wind powered generator that sits under the left canard.

Taken from Wikipedia "Onboard electrical power was provided by a 60 kVA generator. In the event of an in-flight engine failure, emergency power was provided by an automatically deploying ram air turbine (RAT), capable of generating 6 kVA."



This is also always out when the landing gear is down but it's missing from the kit, so I decided to add the resin one.



The hatch that is scribed in the plastic part is a bit smaller then the resin replacement.



So I used some tape to make a template of the resin hatch and transferred it to the fuselage.





After a little bit of cutting using PE saws and then sanding we have a hole.



I know some people have managed to fit the RAT with the intake still in place. But as it's really tight and needs a lot of careful sanding. As my plan from the start was to use FOD covers anyway I just made a big cut in the intake to clear the RAT. I actually made this cut and then realized it was the wrong side and had to make the same cut to the other intake runner as well, but with the covers on nobody will know.



And the RAT glued in place, I still need to redo the panel lines but I'll do that when the fuselage is all assembled.

[Lysus]

Always fun to see you folks do some modification. I'm still a scaredy cat when it comes to that. I do love a Viggen, just those camo patterns appear daunting. I'm in!

[JonMW]

Thanks!

Been working on the cockpit, for this build I wanted to try out the Pilot Replicas resin seat as I like the look of the molded in belts over PE ones. A downside of using this seat is that it's a bit too big. Pilot Replicas made the seat exactly to scale of the real thing not taking into account that the kit cockpit has thicker walls then the real thing due to the injection molding. So the floor needs to be lowered by about 2 mm and the sides of the seat needs a little bit of sanding. As the floor is about 1 mm thick I decided to cut out the center of the floor and then add a 1x1 mm plastic strip to the bottom of the cockpit. Then adding a thin sheet of plastic to the bottom of this as this lowers the floor by 2 mm.











Then painting the seat with aluminium, a light grey and a few greens.



The Special Hobby kit includes some PE parts for the cockpit, but I got the Maestro kit as well as I wanted the details for the back wall and a couple of other as well.



The kit PE instrument panel



The rest of the cockpit PE attached.











I have added a dark brown oil wash to most parts, but I think I might add a little bit more weathering before I'm done.

[snowman819]

Thats one mean looking cockpit.
The viggen seemed to be a bit of a trail blazer with those forward canards that we seem to see on the modern jets nowadays.

[JonMW]

Thanks! Yea the Viggen was a bit ahead of its time on a few areas.

Sorry if this is a bit of a long one

I've got most of the fuselage assembled, this was a bit easier then with the Tarangus JA37 kit even though they are made from the same molds. The reason for this is that the JA had an upgraded engine over the AJ with an added compressor stage. Tarangus/Special Hobby have solved this that same way that SAAB did, by stretching the fuselage just in front of the main wings. The plate the kit manufactures have made both introduses another joint where the fuselage and wings could be twisted and the shape of the sandwich plate is not the exact same shape as the fuselage so a bit of sanding is needed on the Tarangus kit but not this one.

A bit about the engine in the Viggen from Wikipedia:

The Viggen was powered by a single Volvo RM8 turbofan. This was essentially a licence-built variant of the Pratt & Whitney JT8D engine that powered commercial airliners of the 1960s, with an afterburner added for the Viggen. The airframe also incorporated a thrust reverser to use during landings and land manoeuvres, which, combined with the aircraft having flight capabilities approaching a limited STOL-like performance, enabled operations from 500 m airstrips with minimal support. The thrust reverser could be pre-selected in the air to engage when the nose-wheel strut was compressed after touchdown via a pneumatic trigger.

The requirements from the Swedish Air Force dictated Mach 2 capability at high altitude and Mach 1 at low altitude. At the same time, short-field take-off and landing performance was also required. Since the Viggen was developed initially as an attack aircraft instead of an interceptor (the Saab 35 Draken fulfilled this role), some emphasis was given to low fuel consumption at high subsonic speeds at low level for good range. With turbofan engines just emerging and indicating better fuel economy for cruise than turbojet engines, the former was favoured, since the latter were mainly limited by metallurgy development resulting from limitations in turbine temperature.[citation needed] Mechanical simplicity was also favoured, so the air intakes were simple D-section types with boundary layer splitter plates, while the fixed inlet had no adjustable geometry for improved pressure recovery. The disadvantage was that the required engine would be very large. In fact, at the time of introduction, it was the second largest fighter engine, with a length of 6.1 m and 1.35 m diameter; only the Tumansky R-15 was bigger.

Saab had originally wanted the Rolls-Royce Medway as the Viggen's powerplant. Due to the cancellation of the Medway, the JT8D was instead chosen as the basis for modification instead. The RM8 became the second operational afterburning turbofan in the world, and also the first equipped with a thrust reverser. According to aviation author Christopher Chant, the RM8 has the distinction of being the first engine to be fitted with both an afterburner and a thrust reverser. It had a bypass ratio of around 1.07:1 in the RM8A, which reduced to 0.97:1 in the RM8B. The RM8A was the most powerful fighter engine in the late 1960s.

The AJ, SF, SH and SK 37 models of the Viggen had the first version of the RM8A engine with uprated internal components from the JT8D that it was based on. Thrust was 65.6 kN dry and 115.6 kN with afterburner. For the JA 37, the RM8A was developed into the RM8B, achieved by adding a third low-pressure compressor stage over the preceding model, increasing the turbine inlet temperature and fuel diffusion within the combustion chamber. Thrust is 72.1 kN dry and 125.0 kN with afterburner. Due to the increased length and weight of the RM8B engine over its predecessor, the airframe of the JA 37 was stretched in order to accommodate it.

Fuselage together and just a littel bit of filler added.



Also glued in the front resin wheel bay that fits just as well as the kit one and don't need any modifications.





I filled most of the panel lines under the canard using sprue filler as most of them have slightly the wrong shape and don't line up with the panel for the RAT. Sanded it smooth and gave it a light coat of Ultimate black primer to make it easier to see the new panel lines.



I used the Tamiya vinyl tape as a guide when scribing and most of it was done using a Tamiya PE saw as I find that a lot easier then using a normal scribing tool.



For the engine I've added the Maestro PE set to get a bit more detail.



Although the kit details are pretty good for the engine, it's mainly the thrust revers doors that could use the upgrade.











In the PE instructions it pretty much just looks like you're supposed to glue all the PE on top of the kit details. What I like to do is cut off the engine and add a sheet of plastic card so you can't see into the fuselage, and then glue all the PE to the sheet. This way you an also use the small plastic cone in the center of the turbine and add it to the PE.



Now my main wings where pretty much bend so bad out of shape they would not fit. I've talked to Max, the owner of Tarangus, about this and he of course offered me a new wing sprue. I didn't think it was that bad and wanted to see if I could fix it, plus I knew that if it didn't work there was always another option. A friend of mine had a similar problem with his Viggen as well but not as bad as mine. He clamped the wing to a thick steel ruler and put it in the oven for about one hour at 50 degree C. Now my oven is really bad at temperatures that low and you have no idea what temperature you get when setting it that low, and it's really uneven heat in it. So I thought I would try something a little bit different.







The 3d printer I have at work is pretty big and has a nice thick heated aluminium bed that is really flat. So I clamped the trailing edge of the wing to the edge of the bed and used some "scrap", in the form of brake calipers for race bikes, as weights. Turned on the bed at 70 degree C and let it sit for 30 minutes and then let it cool all the way down again. Came out pretty straight and is usable, with the top of the wings attached it evens out the last little bit of twist.



This is the way it looks at the moment, just missing the canards, some small details and a bit of sanding, and maybe cutting the flaps. I hope I can get some primer on it during the weekend and maybe even start putting down some color.

[TommyKillander]

Awesome job with the cockpit !

...and fixing the wing like that is just amazing

I'll keep my fingers crossed that you will make the deadline without the need to sacrifice build quality - keep up the good work buddy!

This build is just epic!


Tommy

[Tomcat64]

Beautiful work Jon, great catch on the wings and the detail in the engine is just awesome

[JonMW]

Thanks guys!

Before I could put on some primer and start with the camo colors I need to get the final pieces on. First thing is the resin flaps, I noticed that Special Hobby made a mistake in the instructions. The AJ version only has three actuators for the flaps, not four like the JA and the instructions say.



So I cut off one of them, and removed the molded in flaps with a saw.



Next up was the air intake and central pylon.



Then I remembered that I had resin ones instead. So I pried off the plastic one and attached the resin one, as well as the resin canards.





Ready for primer



A coat of Ultimate black primer



For color I'm using Mr Paints Swedish paints 058, 093, 322, 326, 507 which are a really good match.



I started with the colors in the corners of the wings and canards and then did the adjacent color using the Maestro masks.



All done, now comes the fun part of unwrapping it.



Came out pretty good, still need to do the underside and the black details.

[Lysus]

I don't know how you didn't lose your mind on that camo...awesome. Dig the crafty work on the mods, too.

[sheppsea]

Very nice work

That was a interesting way of doing the camo? How long did it take working across like that? I think its probably probably better than doing it by colours tbh

[TommyKillander]

Awesome

Brilliant work - that came out perfectly. The MRP paints looks really good


Tommy

[Twokidsnosleep]

Fabulous camo, just fabulous

[DrSprue]

Very cool

[Tomcat64]

Absolutely stunning!

[ElCapitan]

Great job on the camo. I wouldn't have known where to start!!

[JonMW]

Thanks a lot for the comments guys! The camo took almost a week to do, so a bit slower then doing each color at a time. But it did make a bit easier to get everything to fit as it should.

Finished the painting by doing the underside, started with some random patterns in the center of the panels before covering the whole surface.



The plane I'm doing has big exercise numbers on the top side of the wings. These where painted in a easy to wash off white paint so decals won't work.



So I drew up some numbers and 3d printed some cutting templates so I could make masks to paint the numbers.











Then finally I started bleaching the paint by mixing some of the original colors with some white or yellow and painted the center of each patch. Last thing to do for now was to add the decals, it's mostly the kit decals with some taken from Moose Republic AJ37 sheet.

[Twokidsnosleep]

Ok that is solidly cool application of technology and well executed
I notice the number four has a blob of plastic in the corner that would mar it if you wanted to use the plastic parts directly insead of as a masking guide. How do you design the 3D print to have a perfect number shape???
Looks to need a sprue kind of start and end points that are off the number itself perhaps??

[Tomcat64]

Absolutely superb work Jon - speechless

[JonMW]

Thanks!

Ok that is solidly cool application of technology and well executed
I notice the number four has a blob of plastic in the corner that would mar it if you wanted to use the plastic parts directly insead of as a masking guide. How do you design the 3D print to have a perfect number shape???
Looks to need a sprue kind of start and end points that are off the number itself perhaps??

The blob is because I printed it at a bit too high speed and high temperature as I didn't really care about the finish. Printing at the correct speed and temperature gives a pretty good result, like the frame for this base that haven't had any cleanup.



To get the right shape of the numbers I cheated a bit and asked the guys at Tarangus/Maestro. They are working on a masking sheet with all the numbers and some other marking, so they gave me cad drawings of the two numbers I needed.

[JonMW]

Time for another update, it's not a lot left now. First up is a bit of repair, I managed to drop the model and chipped the end of the wing.


The corner of the top part of the wing broke off.


Added a bit of milliput and sanded it smooth.


And put down some new primer and paint, pretty much can't even see the damage.

As this is a AJ version of the Viggen it can carry a more varied weapons load then the JA version. AJ means attack with limited fighter capability and JA fighter with limited attack capability, so the JA was more for air to air combat and the AJ for air to surface/water combat. The AJ could carry different types of bombs, cannon pod, rocket pods, two different types of air to surface missiles, two types of anti ship missiles or a cluster bomb. I wanted to give it a pretty heavy load so I choose two Rb04E anti ship missiles on the inner wing pylons and two Rb05A air to surface missiles on the shoulder pylons.

The RB-04 (Robot 04) is a long-range fire-and-forget air-to-surface, anti-ship missile. The missile was known as the "RB-304" during development and early service years.
While interest in guided anti-ship missiles was subdued in the 1950s, it was not entirely extinct. In 1949, the Swedish government placed a request for a radar-guided, air-launched anti-ship missile. The request materialized as the SAAB "Robot-Byrån (RB) 04", which was first test launched by a Saab 29 Tunnan fighter in early 1955. The early versions of the missile suffered teething problems in regards to the two targeting modes, which were area attack, for striking a big group of ships (like an invasion fleet), and select targeting, where the missiles home in on a single vessel. In the area attack the missile would only target a ship in the group if they were within 1,000 meters of another vessel, this was also in the early electronic age, and changes in this distance required hardware modifications in a workshop.

The Rb 05 was developed as a ground attack missile for the AJ 37 Viggen in 1967, and was issued for operative use in 1972.
It was later discovered that the missile also could be used in air-to-air against slow-manoeuvring aircraft like transports and helicopters.
A TV-guided variant Rb 05B was proposed to the Swedish Air Force in the early 1970s, but was turned down in favour of the AGM-65 Maverick/Rb 75.
The missile would usually be launched after a high-speed attack run on very low altitude and climb to 400m for launch. The supersonic speed was deemed necessary to reduce the threat of surface-to-air missiles. Since RB 05 was roll-stabilized, the aircraft did not need to be aimed straight at the target when launching, and would immediately descend again.
Tracking the flares on the missile, the pilot would then guide the missile optically (the missile's engine was smokeless as to not obscure the view) with a joystick towards the target. Guidance commands were transmitted to the missile via a jam-proof radio transmission link.

The resin missiles glued together


Rb04E painted in white, grey and black Ultimate primer, a little bit of steel paint and a stripe of bare metal foil.


Rb05A painted in white Ultimate primer and detail painted with yellow, tan, black and silver.

[Tomcat64]

That's some really impressive looking ordnance Jon - and great save on the wing-tip repair too.

Looking forward to seeing the final reveal shots now.

[JonMW]

Thanks!

Final update before the reveal and it's time to do the base.


I started with a picture frame and made concrete slab sized pieces of cork gasket material, some of them where torn to create cracks in the concrete.


I then used AK Terrain concrete paste, this is a water based paste that simulates concrete really well.


Using a knife I smeared a thin coat of the paste over the whole base, about 1 mm thick. This is the time that I forgot to take any more pictures, but what I did with the base was first wet the surface before it had dried completely and used a steel ruler to scrape the base flat. I then removed the past from the cracks using a toothpick, just dragging it and letting it follow the gaps I made in the cork. When the cork had dried for 24 hours I started on the painting by first adding some black ink to the cracks, masked the white lines and painted them. I then started to add some variation to the different slabs, first by airbrushing raw umber, raw sienna and grey inks and then finally adding some Ultimate light dirt and concrete wash to the different slabs.


And this is the final result. Reveal thread viewtopic.php?f=604&t=23190

[snowman819]

Very nice. I've used cork to simulate broken tarmac painted black and it works well.
I don't think i could do that camo. Looks nice.