improving the old 1/32 Revell Gripen

[mydesign]

I am a bit late to enter into the “Blue Box of Happiness” group build but writing down the build preparations took longer than thought.
The project is to improve the old 1/32 Revell SAAB JAS 39 Gripen as released in 1991. I can not promise yet if it can be finished, but I will give it a try.

 

Yep…. I know there is a “risk” that JETMADS may come with a new 1/32 Gripen kit as they did with the SAAB Viggen and announced a SAAB Draken….

 

But I have a "weakness" for Swedish jets, and I made the old ID models/ Tigger SAAB J29 Tunnan earlier as seen here on the LSP forum.....

 

OK, let’s looks at this old Gripen kit....

 

The kit #4752 has about 125 parts and contained also a sort of engine, an entry ladder and stores like missiles and fuel tanks. I bought the kit second hand quite cheap many years ago. It was clear that the accuracy of this 1/32 kit was not very good, models built over the years seemed to be too “compact”. But at that time the new Gripen was still quite secret and not a lot of the details were known to the Revell team in 1991. 
A few decades later more data had become available, so I had studied a bit more. A big trigger was that the small 1/72 Revell kit of the Gripen JAS-39C was released in 2014. This kit was made by Revell with SAAB assistance some 25 years later and the outlines of this kit seem to be quite accurate as I made a kit. I could also cross-measure the sections and shapes while building it and made notes. 

So another 7 years later, time to look at the old 1/32 Revell Gripen kit again! 

 

For those who are unfamiliar with the kit, the main parts are seen here. (Note that some parts have already some paint as I bought the kit second hand).
 

 

 

 

 

 

 

 

Stores are a bit crude and seem to be a pairs Sidewinders, RBS-15F missile, RBS-15 anti-ship missile and a single central fuel tank. The cockpit is basic and there is a sort of intake funnel. 

 

The kit decals are for proto/ pre-production? aircraft with stripes (I had seen also kits with very yellowed decals in the past)

 

 

 ================= 

 

A FIRST CHECK-UP
OK. Next, I started to look for several layout drawings though we all know one has to be careful with these.

The 1/72 Revell kit   ( LINK to my webpage:   https://designer.home.xs4all.nl/models/gripen/gripen-2.htm )  was also measured up and notes taken.

Having a few “Jane’s All the World Aircraft” books, the invaluable reference source for aviation professionals, some main data was compared as published over the years in Jane's. 

 

 

Some drawings were scaled up to 1/32 with computer, scanner and printed. I used a good drawing as starting point. 

 

These are some of my prepared drawings 

 

 

… and below with pitot tube drawn in upper view

 

 ======================================================

A big moment is now to compare some bigger kit parts with my drawings.

 ======================================================

FUSELAGE:

 

 

 

It was measured and it seems that the old 1/32 kit is about 21 mm too small in total length.

 

When the forward fuselage section is set on the drawing, the nose planform does not look too bad. The air intakes seem to be pretty good but need a bit more curve at their upper edges near the canards.

 

=======================

WING:

 

The overall wing span is about 10 mm too small. Increasing the chord section in span seems to way to go.

 

 ===============

VERTICAL TAIL:
 

 

 

The tail fin height is about 5 mm too small.

(Note that using the “total height” data of the real Gripen can not be used at it is affected by the landing gear layout).

Multiple small vertical tail corrections are needed here, also at the leading edge and a bigger rudder to be made. 

 

  =============
CANARDS:

 

 

The canards are not that bad. A bit reshaping with some plastic card and extenting their ends with 3 mm each would do it.

Also the kit parts need removal of the stubs (which were probably prototype flutter weights?) and raised details.

 

 =================

 

OTHER IMPROVEMENTS

Other issues for improvement found till now are:

- improve internal details, particularly cockpit 

- improve canopy
- improve the landing gear, doors and gear bays;

- replace wheels;
- kit wing pylons are inaccurate and need modification;
- main exhaust kit part #30 does look too small, it should be about 30 mm in 1/32. A replacement could be a F-18 exhaust for the RB12/ F404 engine;
- improve fuel tank if desired and seek better missiles if desired.  

 ==================

 

FURTHER INVESTIGATION

I tried to find out what may have caused the dimensional inaccuracies in the old Revell kit. Now I saw something interesting: the Jane’s “All the World Aircraft” data from 1988 till 1993 indicated a wing span of 8 meters and length of 14,1 m. Jane’s data from more recent date (2007/2008) showed: wing span 8,4 m inclusive wing tip missile rails and length 14,1 m without nose pitot tube. So they added info about pitot and missile rails. 

 

I estimated the real Gripen pitot tube to be about 0,75 m long (that is 22 mm in 1/32) and the real wing tip missile rails to be about 0,15 m each wide (that is in 1/32 about 5 mm).  
 

This adds up to the length correction of about 21 mm and wing span correction of 2x5 mm. I concluded that the Revell kit team at the time forgot about the pitot tube length and missile rails. The team assumed this to be “included” in the overall Gripen span en length dimensions as stated by the Jane’s data (and probably in SAAB promotion documentation) when making their moulds. 

 

I looked at a lot of photos and kept in mind these issues. 

It seemed that corrections could be done on the Revell Gripen model. Yes, it will not be easy and would need putty, plastic card, putty, card… and a lot of patience… 
Though not perfect, at this point the only option for a better JAS-39C Gripen model in 1/32 scale. 
I concluded that these modification are “do able” so it was decided to improved this old kit to get a better 1/32 scale model of the current SAAB JAS-29C Gripen. 

 

OK, this was a long first post about the investigation. Next, first attempts to build the kit!

 

Meindert

 

 

Edited November 10, 2021 by mydesign

[mgbooyv8]

Hi Meindert,

 

Great that you start building this  infamous Gripen model here in the group build! 

I remember an article in the magazine Scale Models in the year the kit was released, written by two Swedes.

They indicated many shape errors. Maybe it is worth digging it up before committing to the saw.

 

Cheers,

 

Peter

[mydesign]

Hi Peter

 

if you can find that old magazine article, that would be nice.

 

I also had a subscription to Scale Models but those old mags were discarded when I moved and had lack of storage space.

 

Cheers, Meindert

[PieterGSXR]

Hi, Meindert,

Nice ! That will be a lot of work ....

Go for it !

Gr, Pieter

PS, O, and the "Grippen" from Jetmads, that's gona be a long time from now, I think..

[Phantom2]

Hi!

 

This is the worst kit I have ever built!

Never have I used as much putty, never have I had to sand and grind as much as on this awful kit!

 

Sorry, I don´t want to let you down, you are a brave man to get in a close fight with this kit!

 

I will follow your build, that´s for sure and I really whish you good luck, mate!  

 

If Revell only had asked SAAB, I´m sure SAAB had helped them to do a really good model, but no, Revell used some publicity photos for the dimensions!

 

 

 

Stefan 

[Scotsman]

I once swapped a Revell Gripen for a Tamiya F-14 and I'm certain I got the better deal..

 

Us old timers remember a project here by someone to produce an accurate model, and eventually gave up after a long and painful struggle - so I wish you all the best , but I think I'm fairly certain this is one of the most inaccurate kits ever made , and yes I'm including Trumpeter 

 

I wish you be best of luck! 

[mydesign]

Maru, thanks for the link to the drawing, I was aware of this website.

 

Next....

  =============

WHERE TO IMPROVE THE SHAPES
The next issue to tackle is to discover “where” to correct the fuselage, wing and vertical tail shapes of this 1/32 SAAB Gripen.

This took quite some investigation, also by measuring the 1/72 kit and looking at drawings and many many photos. Helpful was my home made 1/32 kit planform drawings to compare with kit parts. This was done with the computer, scanner and printer by enlarging drawings from 1/72 to 1/32 by factor 2,25.  

 

COCKPIT
A quick check was done regarding the cockpit parts like the tub as I wanted to investigate proportions and width. In 1/32, detailing the cockpit is worthwhile. In those days it was still a bit secret with many photos showing the “mock up” at the time. Here the basic Revell kit parts are seen.

 

 

 

 

A sort of Martin Baker mk.10 is suggested. That would be close to the MB mk.10 SL seat used in the real Gripen.
I found that CMK had a set for a Mk.10 but is was far too wide to fit the kit tub.

 

 

 

The basic Revell seat was taped together and checked with a same 1/32 Kitty Hawk Mirage 2000 Mk.10 seat. I concluded it would be a good idea to use this KH seat and update it. A quick check was done with the kit tub as seen here... 

 

 

 

 

 

 

More details will be added later on. The kit cockpit tub is very simple and at this stage only the base part will be set inside the fuselage nose. It can be used as platform to add at the details to be done at much later stages to avoid damage due to handling. A new instrument panel with side panels will than be made from scrap. 

 

FUSELAGE
As noted earlier the kit fuselage is far too short. For increasing the fuselage length several cuts are required using the razor saw.

  

[A] increasing the upper fuselage halve length: 

(1) the first large cut was made in the upper fuselage halve aft of the spine exhaust... 

 

(2) at the separated nose section a vertical cut was made at both side walls at the cockpit sill.....

 

  

 

 

The nose and cockpit shapes were compared with the drawing… it looks more accurate now....  

 

 

Note: as a result of the cockpit sill lengthening (with 4 mm) a 4 mm slightly longer “clear canopy” is needed; the kit part will be used: by sanding and polishing out the moulded kit frames and adding new rounded frames from card at the front edge and rear edge.    

 

[B] increasing the lower fuselage halve length:

 

(3) make a cut slightly in front of the moulded nose gear bay. 
 

  

 

(4) make a cut in front of the main gear bay opening

 

 

  

It was also decided to deepen the rear of the nose bay by removing a part of the nose gear bay "roof". 

 

In order to get more strength, a small secting was repositioned of the lower fuselage aft of the canard station. This small section was moved to the rear and now sits near the wing leading edge root...

Parts can be shiften to get the 17 mm extension between nose section and rear fuselage as seen here...

 

 

.... and seen here the lower sections shifted 17 mm...

 

 

  Here the overall idea is seen, making increasing the total length 4 mm + 17 mm = 21 mm.

 

  

 

A CHECK WITH THE LANDING GEAR

The lengthening of the fuselage affects the landing gear obviously. First kit doors and landing gears were cross checked. 
 

 

The distance between centers of nose wheels and main wheels at the real Gripen is about 5,25 m (so about 164 mm in 1/32). This number will be used to establish the location of the nose gear strut and the main gear bays and struts. It was concluded looking at the made cuts and shifted parts that the struts can be appropriately set at a correct location at the later stage.

The main bays can be set at per fit at the changed rear fuselage insides.

 

It was found that the kit main door parts are inaccurate. As the big main forward doors will be kept closed as seen on most parked Gripens and the main gear leg location will be kept, the effort is simple. The “closed forward” main doors will be “virtually” lengthened with a sort of card fairing (to be shown later).
It was also found that the main wheels of the kit are too small in diameter (2,5 mm); but the kit nose wheels can be used (only about 0,5 mm too small) though these are found also in a ARMORY resin set; more about that later on.  

 

INTAKES

The intakes were not that bad and can be reatined and installed with their kit part splitter plates. Inside the fuselage it was decided to suggest a sort on engine air funnel with card with an engine fan. A bulkhead was made and set in the upper fuselage to ensure it would not interfere with any main gear bays. I suggested a fan but later found out using the kit part was also an option, well I forgot about this.
 

 

 Note that the forward fuselage and aft section are not joined yet at this stage as first some work on the wing will be done.
 
EXHAUST
A sort of jet pipe will be set at the front of the exhaust with a part found in the spares box from probably a Eurofighter. (the kit “engine” parts were thus not used).

 

  

The prepared and modified forward fuselage was assembled with pieces of card to get the required plugs of appropriate length. At the mid sections also card was set also internally to get strong joints.  

 

  

Card , putty / car filler and a lot of sanding was needed.  When the cockpit sill was fine, the intakes were set with their kit part splitter plates. 
Again puttied and sanded.
 

 

Inside the fuselage it was decided to suggest a sort on engine air funnel with card with an engine fan. A bulkhead was made and set in the upper fuselage to ensure it would not interfere with any main gear bays. 

 

Note that the forward fuselage and aft section are not joined yet at this stage as first some work on the wing will be done. 

 

 -----------

WING MODIFICATION
As noted earlier each wing half needs an extra about 5 mm span increase at the rear (including the inboard trailing edge flap); (total wing span increase 2x5 mm = 10 mm).
The wing sweep at the leading edge is also improved that way.
 

 

The inaccurate missile wing tip rails were be separated with a razor saw also enabling with sanding in flow direction a sweep correction at the wing tip ends. The inboard flaps were also separated.

   

As regarding the wing, it was found also that the wing root span extension of 5 mm at the rear should be a bit less at the leading edge. At the leading edge root a small additional fairing kink is seen on the real Gripen. This will be made later on.

 

The wing ailerons looked OK so were not changed. The spanwise pylon stations were checked with the 1/72 Revell kit but looked good enough.
Though this wing correction is not 100% it improves the looks a lot. The wing root inserts will be made with card and putty. Inside, thick strips were glued.

 

The upper and lower wing sections were joined, clamps used.  

 

  

The gaps will be closed with card between wing and the rear fuselage and puttied. All was aligned with  the upper fuselage to keep any ridges and curves as limited as possible. 

 

    

  

The small indented grills were also filled with putty as they are inaccurate and at wrong locations. Some new engraving will done later.  
The lower areas are seen here... 

 

 

A check was done with the drawing and it looked much better now! (note: camera lens shows a bit distortion)

 

  

 

The upper rear fuselage can be kept as per kit and will be used to install the vertical tail and (changed) exhaust later on. 

 

 

To be continued...

 

  

 

 

[bdthoresen]

Wow, that’s some awesome work. I really am enjoying this build so far.

 

In your last photo, it looks like the flaps and ailerons will need modifying to straighten out the trailing edge, increasing their span slightly. But, it looks like that will not be a huge deal considering your work so far…….

 

Please keep the updates coming!

 

Thor     

[LSP_Kevin]

Superb update, Meindert!

 

Kev

[Alain Gadbois]

Excellent work on the many corrections!

 

Alain

[KiwiZac]

This is fascinating, I love seeing this kind of build. While 1/32 is too large a scale for me when it comes to the Gripen I'm curious and excited to follow along.

  

On 11/10/2021 at 9:59 PM, mydesign said:

Yep…. I know there is a “risk” that JETMADS may come with a new 1/32 Gripen kit as they did with the SAAB Viggen and announced a SAAB Draken….

It seems to be a given in this hobby that someone will do an incredible amount of corrections to an existing kit or an entire scratchbuild and, days either side of the RFI being posted, a manufacturer announces a kit of the exact same subject 

Edited November 29, 2021 by KiwiZac

[geedubelyer]

You are doing a fine job Meindert. 

 

Perhaps you are paving the way for an accurate kit from well known manufacturers? You just know that as soon as you finish all of this hard work someone will announce a new IM kit. 

 

I look forward to seeing your next update.

 

Cheers.

[Scotsman]

Quote

It was found that the kit main door parts are inaccurate. 

 

Wouldn't it easier to list those parts that are accurate? - it wouldn't take too long

 

Seriously what an astonishing demonstration of determination and modelling skill - keep up the great work!

[dmthamade]

Lots of work to make an accurate build. I remember buying/building this kit back in the day. Looked fine to my eyes, then. I just read the news the Boeing Super Bug is out of the running for the next Canadian Fighter jet, leaving the F-35 and Gripen the choices left. Decision still far away, but maybe the kit will be popular again?.....

 

Don

[mydesign]

OK, on to next steps, which shows the progress after quite some hours of modelling....

 

VERTICAL TAIL
This needs corrections as well with an increase vertical tail height at the lower base by 3 mm and at fin top by about 2 mm (total increment = 5 mm);
With a razor saw, several cuts were thus made.
 
For the increased height, a few strips of card were used. The upper tail section will be a piece of card 2 mm.  It was decided not to change the vertical tail fairings, though not 100% accurate but good enough. 
 
These root base of 2 x 1,5 mm thick = 3 mm card sections were set on the rear fuselage. The rudder will also be enlarged with card. (note that the raised knobs were sanded off later on). 

 

MAIN ASSEMBLY

An important step is now to join the forward and rear fuselage-wing assembly. 
It was crucial to check symmetry and get enough strength with long strips of thick sprue. An exciting moment! 
   (prepared vertical tail is also seen)
 
As seen, the air funnel inside and extra stips will be set between forward section with spine and rear spine. Let dry for at least 24 hours.

 

 

MAIN GEAR BAYS 
Back to the landing gear as noted earlier. For the corrected main bay opening shapes, a piece of curved card insert was made to fit. This way, the main closed doors will be “virtually” lengthened 10 mm. 

 

 

Also bits of card were needed to get more strength and all set with clamps to dry. 

 

Making this curved card insert took quite some time. Note that the main closed doors are part of this insert.

 

 

 

Putty will be needed and card will be used at the upper spine…. 

 

A check was made with the drawing and it look OK. The spine insert here is 17 mm in 1/32.

 

 

IMPORTANT CHECK

A check was done and now a 1/32 Gripen model is progressing that is far more accurate in shape :

 

(1) increased fuselage lengths of 4+17 = 21 mm.

 

(2) with corrected wing span 2x 5 mm at the rear and the leading edge sweep looks much better now. 
Note: at the ailerons, the trailing edge sweep (about 1 degree) is not entirely accurate but it was decided not to mess with the thin trailing edges here.

 

Now a lot of putty and sanding is needed... several passes are needed..... 

 

 

    (photo here shows still the uncorrected gun fairing location) 

 

Each intake upper corner near the canard station should be a bit more curved. Sanding was done, be careful here as the plastic is thin. I had to make some repairs at the intake corner insides here as the plastic was very thin. A small fairing was added from strip. The better result is seen here… 

 

The spine exhaust aft of the cockpit took some work to get a perfect symmetrical result.

 

 

Some small amounts of putty and sanding still needed...

 

 

GUN FAIRING 
I found a bit too late that the lower gun fairing needs to be lengthened in the middle by about 12 mm and relocated as well. So the kit shape was cut off horizontally with a razor saw. ... this is risky!

 

It can be done.

 

Some card was set. A 12 mm section was set in the middle and putty and sanding needed again!

 

 

  

 

INBOARD FLAPS

The inboard flaps are still separate parts. They will also be used to suggest a slightly better trailing edge angle as I had to rotate a bit the wing planform. Measuring and dry fitting was done now. The gaps between flap and fuselage will be kept but not too wide with card and putty.

 

Pieces of card (5 mm width again) are needed… and putty! 

 

 

 

The changed inboard flap also adjusts the trailing edge sweep which looks good now.

 

 

VERTICAL TAIL
The corrected vertical tail was set onto the rear fuselage. Ensure a vertical sit! Putty was needed at the base. 

 

 

 

A small correction was also needed at the lower base as seen here.
 

The rudder was made heigher / enlarged with card and putty as well.

 

At the wing kink/ leading edge aft of the canard station it was found a small extension was needed as seen on real Gripens. It took quite some time to see this as it is missing in the original kit and is situated at the mid fuselage extension. (see drawing check above). The small extensions were made with a bit from the spares box, putty and sanding. 

 

 

Here the overall result is seen of the corrections till now.

 

 

The model still needs some small putty clean ups and than a first grey base primer. Than a photo check will be made with the camera. 

 

 

..... to be continued....