1/32 Saab JAS39 Gripen - So, the Nordic saga begins...

[ollieholmes]

This should be interesting to watch but alot of work is involved.

[Derek B]

This should be interesting to watch but alot of work is involved.

 

Indeed Ollie. Once I have discussed with my resin casters how they wish to handle the mouldings, it will dictate how I go about mastering this kit.

 

Cheers

 

Derek

[Derek B]

Small update. I have examined both of the 1/48 scale Kittyhawk and Italeri JAS39C and B kits and have concluded that they are very close (but not identical) in overall shape and size, which leads me to believe that a common data or reference source have have been used for them during kit development.

 

However, when I checked them against the 1/48 H & P drawings, although reasonably close in span to the drawings, they are both noticeably longer in fuselage length. This now caused me to doubt the actual published dimensions of the JAS39 Gripen. The only figure that I could find for the full size Gripen that seemed to agree across various references was the wing span, so I used this as my scaling reference point.

 

The problem may be down to differences in interpretation of dimensions with and without nose probe and wing tip missiles which can alter the size of the model dramatically (this is where primary source information is essential as internet dimensions all too often just reproduce basic data and errors with no verification what so ever being carried out to determine if they are in fact correct).

 

Both 1/48 scale kits look correct in shape and proportions against photographs, so I think that I shall scale the drawings to the kit dimensions and then enlarge them to 1/32 and see how the Revell 1/32 kit stacks up against them.

 

Derek

[jenshb]

Interesting...are you saying both th Italeri and KittyHawk kits are longer than the drawings show?  By how much?

 

Jens

[Derek B]

Interesting...are you saying both th Italeri and KittyHawk kits are longer than the drawings show?  By how much?

 

Jens

 

Yes Jens. It will probably take me a while due to work and other commitments, but I want to verify from the CMK H & P drawings (which are 1/72 scale in my copy) that my 1/48 drawings are the correct size.

 

To start with, I will enlarge the 1/72 drawings to 1/48 scale and compare the 1/48 scale kits against them again to see if I still get the same results (which I shall show pictures of). If still confirmed, I shall resize the plans to match the kit size as closely as possible and enlarge them to 1/32 and compare the Revell kit to them. I do not know at this stage if I shall have to amend the drawings or not. 

 

Derek

[Starfighter]

Don't you think scaling the plans using the dimensions of the real plane would be more accurate? Interesting project BTW, gotta love the Gripen!

Edited November 21, 2013 by Starfighter

[Derek B]

Don't you think scaling the plans using the dimensions of the real plane would be more accurate? Interesting project BTW, gotta love the Gripen!

 

Hi Starfighter,

 

That is what I had done. However, at the correct published data for the span in 1/48 scale, the plans do not match either of the kits accurately and certainly not the fuselage, and as I had enlarged the the same drawings to 1/32 scale, there is now doubt in my mind.

 

I have now enlarged the 1/72 plans to 1/48 so I'll see how they work out before I proceed any further.

 

...Your right, you've gotta love the Gripen!...

 

Derek

[Derek B]

I managed to scale up the CMK 1/72 H & P drawings to 1/48 scale and reassesed the Kittyhawk and Italeri 1/48 scale kits of the JAS39C and B kits again.

 

First of all, a comparison of the two 1/48 kits themselves, as I am using these as a 3D reference for my Revell 1/32 Gripen rework (apologies for the poor quality of the phtographs that follow).

 

Comparison of Kittyhawk and Italeri 1/48 Gripen kits

 

I know that this looks like an air disaster, but it only the more useful external components from both kits.

 

The lighter grey-green coloured parts are the Kittyhawk JSA39C parts and the darker grey parts are the Italeri JAS39B parts. As can be seen, both kit parts are close to each other in terms of overall shape and size even though the breakdown of both kits differ noticeably.

 

 

Fuselage comparisons. The Kittyhawk single seat fuselage is placed directly over the Italeri two seat fuselage - both match fairly closely in fin and rudder shape.

 

Both fuselages are also close in size and shape up to the intake junction (incidently, both kit intakes are so close in shape and size that they could be interchanged with each other).

 

The Italeri wing placed over the Kittyhawk fuselage to show that it is close to the Kityhawk wing in terms of size and fit (not quite exact, but could easily be made to fit with some very minor adjustment).

[Derek B]

This time we see the Kittyhawk wing on the Italeri fuselage - same comments apply as for above.

 

Check against 1/72 plans enlarged to 1/48 scale

 

Both kits placed over the enlarged 1/72 CMK H & P drawings now enlarged to 1/48. Both kits are fractionally longer than the drawings (by about 2mm). The JAS39B drawing length is 306mm. The actual kit length (minus probe) is 308mm. The published length of the full size JAS39B aircraft when calculated at 1/48 scale is 308mm, so the kit length is spot on.

 

Italeri wing parts on H & P drawings. Slightly oversize on the trailing edge but a pretty good match to the plans.

 

 

 

I worked out that if the cockpit section on the drawing is moved forward by about 2mm both the drawing and kit align. The only real discrepency between the JAS39B kit and the drawing is the shape and size of the 'hump' aft of the canopy. Examination of photographs of the actual aircraft indicate that the drawing is closer - I think that some 'adjustment' may be required here to make it look correct (the kit area looks too shallow and short whereas the drawing is longer and deeper).

Conclusion

 

I am now much happier with the enlarged 1/72 CMK H & P plans than I was with my original 'Best choice' 1/48 scale plans which are the same as the H & P plans. The Best choice 1/48 plans that I had originally used were forshortened in the front making them noticeably shorter than both of the kits (this was almost certainly a copying or scanning defect); at least I now know that the drawing is only 2mm off the correct length in 1/48 which can be corrected once the drawings are enlarged from 1/72 to 1/32 (+ 225%, in which case the 2mm error will now be 4.5mm). 

 

Stay tuned...

 

Derek

[jenshb]

It never even occurred to me to check that book   When you say the Best Choice plans are foreshortened - did something go wrong in scanning?  Any chance you could compare these two plans?

 

Jens

[Derek B]

It never even occurred to me to check that book   When you say the Best Choice plans are foreshortened - did something go wrong in scanning?  Any chance you could compare these two plans?

 

Jens

 

Hi Jens,

 

It is difficult to tell the difference with the plans side by side, but it is noticeable once the kits are overlaid (the only way to demonstrate this would be for me to hand trace the best choice drawing and overly it on the H & P drawing). I think that you are correct in thinking that something probably did go a little awry with the scanning. I printed the scanned image at 100% but I now know that it came out undersize compared to the enlarged H & P drawings.

 

Regards

 

Derek

[jenshb]

Weird...I wonder if the drawings in the Best Choice could be undersized or distorted to fit on an A3 sheet?

 

Jens

[Derek B]

Weird...I wonder if the drawings in the Best Choice could be undersized or distorted to fit on an A3 sheet?

 

Jens

 

Jens,

 

The original best choice boo plans would most likely be OK but something most likely occurred during the scanning process to distort them (and perhaps they didn't quite scan at 100%), hence the issues with my copy. Happily I now have something tangible to work with.

 

Cheers

 

Derek

[Derek B]

Now that I have a level of confidence in the CMK H & P drawings, I scaled them up directly from the book (from 1/72 scale) to 1/32 scale (+225%).

 

I extended the two seat Gripen drawings forward fuselage by 4mm just aft of the canopy sloping bulkhead. Although this measurement is relatively small in 1/32 scale, it made (to me eyes anyhow) a huge difference to the appearance of the drawings - the aircraft now looks more correct in the hump area aft of the canopy and generally much more sleeker.

 

I carried out a similar exercise with the single seat Gripen drawings. This time I extended the forward fuselage by 2.5mm at the point where the avionics heat exhaust is aft of the canopy (cross section E on the drawing). This also maked a marked difference to the overall appearance (for the better).

 

The overall span was between 0.5 to 1.0mm less than required but I can adjust this during build - I am satisfied that the drawings now reflect the actual size of the full size aircraft in 1/32 scale (which is wothout nose probe and over the wing tip launchers).

 

Corrected 1/32 drawings

 

 

 

Revell kit major components laid on plans in best fit position.

 

 

Revell kit fuselage repositioned to where the avionics heat exhats break line is featured on the fuselage aft of the canopy (cross section E on drawing). Intake break line now aligns, but the cockpit is still short and out of position.

 

Revell kit fuselage now moved further forward to the best fit position.

[Derek B]

The saga of the 'false' Gripen

 

Now that I had established the correct shape and size of the Gripen, and had the drawings to prove it, I was curious to see if Revell had in fact possibly misinterpreted the published Saab JAS39 Gripen dimensions as being overall dimensions and not minus the nose probe and over the wing tip launchers as already established? Let's see...

 

Here we see the Revell kit components loosely assembled as intended and positioned within the drawing parameters.

 

 

 

 

 

I think that the above photographs indicate that this was very much a probability...Let the saga continue...

 

Derek