Kitbash of the first prototype F-5G, aka F-20 Tigershark

[Drew T.]

Hi everyone, I’m back with my next project already in progress, it’s a kitbash of the first prototype of the Northrop F-20 (which started out as an F-5G).  I’ve always liked the looks of this airplane, even more than the F-5 on which it was based.  Unfortunately, Northrop could never make any sales in competition with the F-16 during the early 1980’s.  In the beginning, they had hoped to build on the success of the earlier F-5E, but when restrictions were lifted on selling the F-16 to  foreign countries, they all went for the F-16, as it was the default choice for the USAF and its allies. 

 

The three F-20 prototypes were painted with a few different paint schemes, but my favorite by far is the “Coca-Cola” red and white scheme used on the first prototype at the 1983 Paris Air Show.  A few years ago, I came across this excellent build on Hyperscale of an F-20 in this paint scheme: 

 

https://www.tapatalk.com/groups/hyperscale/f-ing-sports-plane-f-20-tigershark-1-48-t505093.html

 

While the Freedom Model kit is an improvement on the old Monogram F-20, it has some shape issues with the fuselage and wings per the Hyperscale post.  Also, both of these kits depict a “true” F-20, which the 2^nd and 3^rd prototypes represent.  The first protype was built earlier in the F-20 program when Northrop thought a simple “re-engine” of the F-5E would result in enough of an improvement in performance since they were not yet fully competing with the F-16.  At this point, Northrop was still referring to the plane as an F-5G.  The 2^nd and 3^rd prototypes had a new ejection seat, enlarged canopy, and digital cockpit display with upgraded avionics to better compete with the F-16.  The F-20 designation came about to differentiate itself from the older F-5 design. 

 

I purchased the below book on the F-20, written by Paul Metz, who was a Northrop test pilot at the time and had lots of flight time in the F-20.  He later test flew the F-22 for Lockheed Martin.  Below is a link to the book.  I highly recommend it if you want to build an F-20 or just want to learn more about the plane.

 

https://daviddoylebooks.com/usaf-jet-aircraft/northrop-f-20-tigershark-ginter-air-force-legends-228-by-northrop-test-pilot-paul-metz

 

Since I’m building the first prototype, I’m closely following the build log posted on Hyperscale.  This meant I would use the fuselage from the Freedom Models F-20 and the nose and wings from the AFV F-5E.  Although the first prototype F-20 used the same wing as the F-5E, the shape of the Freedom Models wing is oversized in comparison with the wing in the AFV F-5E kit.   Below is an overview of the kits and aftermarket I’m using.

 

 

The KASL cockpit is really nice.  Although it’s meant for an F-5E, most of it carries over to the first F-20 prototype.  The F-20 book I mentioned has drawings of the instrument panel and side consoles of all three prototypes, but unfortunately, it seems that no known photos exist of the cockpit of the first prototype.  Based on the drawings, I modified the KASL cockpit as shown below.  This mostly involved using Anyz switches and dials on the left console, as well as scratchbuilding a throttle quadrant, as it is shaped differently from the F-5.  Also, the right side of the instrument panel is different, since the F-5 has gauges for two engines, while the F-20 has digital gauges for a single F404 engine.  Also, the first prototype had flight test instrumentation installed in place of the HUD and radar scope in the center of the instrument panel.

 

Original KASL cockpit tub and instrument panel:

 

 

Modified cockpit tub:

 

 

I also added some detail to the side panels and along the top rail where the canopy sits:

 

I added some styrene for the canopy framing along the front of the canopy, as well as some Archer raised rivets.  The KASL parts really add some nice detail to this area.

 

 

 

Painting was accomplished with Mr. Color paints.  I used various tiny Anyz decals for the labels on the consoles and dials on the instrument panel.  I then applied an Ammo PLW Black Night wash over the details and some oil paint on the ejection seat cushions to highlight detail.  I didn’t bother with any real weathering in the cockpit, since I figured these prototype machines were kept pristine since they were shown to prospective buyers. 

 

 

 

 

 

With the cockpit finished, I’m ready to continue with main assembly.   Thanks for looking!

 

Drew

 

 

Edited November 20, 2024 by Drew T.

[A-10 LOADER]

As usual, a fantastic start on this one Drew !! Looking forward to following along.

Steve

[habu2]

Several years ago I was fortunate enough to attend a presentation by Paul Metz, afterwards he was kind enough to autograph my copy of his Ginter F-20 book.

[Gator52]

Awesome project Drew; does the first prototype still exist?

 

I don't have any F-5/F-20 kits, but I do have several Wolfpack T-38s tucked away...might just have to pull one out soon!

 

Chris

[habu2]

#1 (062) crashed in Korea in 1984

#2 (063) crashed in Canada in 1985

#3 (064) is the only surviving F-20, it is on display at the California Science Museum in Los Angeles California 

 

.

 

Edited November 20, 2024 by habu2

[Joe Hegedus]

58 minutes ago, habu2 said:

#1 (062) crashed in Korea in 1984

#2 (063) crashed in Canada in 1985

#3 (064) is the only surviving F-20, it is on display at the California Science Museum in Los Angeles California 

 

.

 

I think both of those instances are discussed in detail in the Ginter book; they both had the same root cause that was, IIRC, basically a g-induced disorientation of the pilot after a particular maneuver.

[Drew T.]

Thanks for the kind words everyone!  Yes, Paul Metz goes into detail on the crashes of the first two prototypes which were due to high-G pilot disorientation in the Ginter book.

 

I’ve managed to make a bit more progress, so here’s an update.  I have the cockpit tub installed in the nose and have the nose section completed.  I used stretched sprue to replicate the canopy lip seal that goes around the edge of the top edge of the cockpit.  I also cut in rectangles on the cockpit sill to represent the receptacles that accept the canopy latches.

 

 

 

 

 

 

 

 

 

 

[Drew T.]

 

The bottom of the nose under the cockpit took some work.  Both the F-5E and the F-20 have vents in this area, but they are not the same.  I filled in the ones in the AFV kit and cut in new ones.  I had to do this a couple of times since I had them in the wrong position the first time.  Finding good references for this work is difficult since only one F-20 still survives.  I pretty much have to rely on photographs of the last F-20 on display at the California Science Center. I also drilled out the two lights under the cockpit, painted them Aclad Chrome, and glued on a clear plastic lens.

 

 

The next area I tackled was the underside of the fuselage.  My intention is to use as much of the F-5 kit as possible, as it appears to be more accurate in shape.  For example, the wings of the F-20 kit are oversized in width, length, and thickness, and since the F-20 prototypes used the F-5 wings with minimal modifications, I’ll use the F-5 wings.  Below is a comparison of the F-5 vs F-20 wings. The F-5 wing is on top and the F-20 wing is on the bottom.

 

 

I’m also using about half of the F-5 underside fuselage.  I did have to graft on the rear underside of the F-20 fuselage, as it’s single engine design makes this area different from the F-20.  However, the F-20 fuselage is too wide, so I cut a couple of slots along the length of the rear-bottom of the fuselage, removed a bit of material until the F-20 fuselage width matches the F-5 fuselage width, and closed up the slots.  I also had to graft on the undersides of the F-20 intakes, since they are larger than the F-5 intakes.  However, I had to use sheet styrene to space out the intakes, as they are positioned farther from the sides of the fuselage in comparison to the F-5. Below is the initial position that was too narrow.  You can also see the two cuts I made that run along the outer edges of the rear of the fuselage.

 

 

The below image shows the intakes at the correct spacing.  The Aires wheel wells and speed brake bays have also been installed.  As typical of most Aires sets, they require thinning of the plastic, but I was able to eventually get them to fit.  They were actually too small to fit in the opening in the wing, so I used sheet styrene to fill in the gaps.  I also filled in some of the panel lines with rubberized CA and opened vents to match my reference photos.

 

 

 

 

I added the raised panel with beveled edges to the bottom of the wings, as they exist on the F-20, but not the F-5.  The F-20 kit already has these, but again, it was easier to just add them to the F-5 wings since the AFV kit has a more accurate shape.

 

 

The next area to tackle was the intakes.  The kit provides a very crude shape of the intake trunk, but it was blocked off.  I opened it up and glued it to the fuselage bottom.  It was difficult to place the intake trunks, as the correct position was lost by not using the F-20 fuselage bottom.   Once the placement was correct, I used a couple of pieces of sprue to secure the intake trunks and make sure they would stay square with the bottom fuselage during assembly.  I used epoxy putty to smooth out the bottom of the intake trunk.  I also added some sheet styrene to the sides of the intake trunk to even out the surface.  In reality, the bottom of the intake trunk has a slight incline as it moves back toward the engine, but the kit does not accurately capture this shape.  However, I didn’t bother fixing this error, as it would be hard to see when the kit is assembled.

 

 

Then I applied a coat of white Mr. Surfacer 1500 to make sure everything looked ok.

 

 

I then glued on the sides of the intakes and applied epoxy putty along the seams in the intake.  Before the epoxy set up, I used a wet cotton swab to smooth it out since it would be difficult to sand after it sets.  Also note the profile of the intake.  The shape of the front of the intake is wrong, as it bows out slightly toward the upper sides.  In reality, the sides of the intake lips should be  vertical and parallel with the intake splitter.  I corrected this as much as possible by careful trimming of the side of the intake lip and sanding down the outside wall of the intake.  The bottom image shows the right side (left in the photo) intake profile corrected and the opposite side uncorrected.

 

 

Next, I painted the intakes black.  It seems weird for a modern jet, but all the reference photos of the F-20 show what appears to be either dark gray or black intake trunks.  I always assumed intake trunks were white to make any debris or cracks in the intake more visible, so I’m not sure why the would be black.  The upside for me is that any rough areas in the epoxy putty were hidden under the black paint, as well as the incorrect shape of the intake trunk.

 

https://lh3.googleusercontent.com/pw/AP1GczN7Z3HZ7qBjhR3totahTg1Kiuy_QTNLcRK72b6-jAZUI5-6LggNeHtGzJ3gj8-vdEQ_ic6pXgUOPJ2sLbil1q8zC4jL_2mCzYiFXL_bePm6jU_KCXMx6OpaXGPfhIyzJbW8YRja4vC7kNMRZ6gob0J2-A=w1787-h979-s-no?authuser=0

 

Using 0.005"  thick strip styrene, I added dividers in the top and bottom of the back ends of the intake splitters.

 

 

After studying reference photos, I noticed that the position of the three tall, narrow vents on the intake splitters were positioned wrong.  The kit has them positioned vertical, but they should be angled forward about 10 degrees from vertical.  The front edge of the intake splitter and intake lip are also at a 10 degree angle, but again, the kit has everything positioned vertically.  The angle of the edge of the intake splitter and intake lip could easily be fixed by sanding, but the vents were more difficult to fix.  The kit has three shallow depressions to receive the photoetch vents. 

 

 

To reposition these depressions, I made my own vent assembly using sheet styrene.  I used my Silhouette cutter to cut a pattern for the three vents in 0.010” thick styrene.  I then glued this pattern over another sheet of 0.010” styrene and glued the photoetch vents in the depressions. 

 

 

 

Finally, after carving out a rectangular depression in the intake splitter, I glued in the vent assembly, making sure the vent assembly was flush with the outer surface of the intake splitter.

 

 

There is also a rectangular vent on the top of both air intakes that the FM kit doesn't do a very good job of replicating and it looks oversizsed to my eye.  I tried carving in vent louvers that would look more accurate, but ended up buggering up the part.  Instead, made new vents from 0.010" thick sheet styrene.  Similar to the vents on the intake splitters, I carved in a rectangular depression in the kit part to accept the styrene vent I made.

 

 

Another problem in combining the F-5 and F-20 kits is that the width of the F-20 fuselage is wider than the F-5.  In the post on Hyperscale, the modeler cut slots along the length of the F-20 fuselage to remove material to decrease the overall width.  However, I noticed that the spline that runs along the lower rear section of the fuselage on the F-20 kit is oversized and increases the overall fuselage width.  This is easily fixed by sanding down this spline so that the width of the upper fuselage matches the lower fuselage.  Below is the fuselage side before modification.

 

 

And here’s the part after modification.

 

 

That's all for now.  Next step is to get the upper fuselage ready.  Thanks for looking and Merry Christmas!

 

Drew

 

 

 

Edited December 23, 2024 by Drew T.

[Drifterdon]

Really amazing attention to detail Drew.   Love the F-20 (F-5G).

[A-10 LOADER]

Holy cow, amazing work here Drew !!

Merry Christmas.🎄

Steve

[Drew T.]

Thanks guys! Merry Christmas! 🎁 

[Thadeus]

Looking very good. Pretty crazy stuff combining two kits like that, but You're doing great work.

[Drew T.]

Thanks Thadeus!

[Drew T.]

Hi guys,  it's time to post an update.  I now have this project to the priming stage so I'll go over everything I did to get the main assembly complete.  

 

Joining the nose section of the AFV kit to the rear fuselage of the FM kit resulted in a step between the two sections around the area behind the cockpit and above the intakes.  I dealt with this by recontouring this area with putty.  I don't like to use typical solvent based putty for thick applications like this because it can shrink over time even after it's dry.  Instead, I used UV light curing putty from Colad.  It cures instantly with a good UV light and should never shrink.  It's about as hard as plastic and sands well.  It holds up decently to scribing, but it can crumble when doing this, so a careful hand is required.  It doesn't bond as well to plastic as solvent based putty, but you can apply a layer of thin CA over it if it starts to peel away from the underlying plastic.  The putty is semi-transparent, and it appears brownish-gray in the photos.  

Because the AFV wing is so much thinner than the FM wing, using the AFV wing with the FM fuselage sides results in an opening at the wing root.  I filled this with strip styrene and rubberized CA.

 

 

There are what I think are three fuel doors arranged along the left side of the fuselage.  The kit does not represent these well, so I made my own from styrene sheet circles.  I drilled corresponding holes in the fuselage side and glued in the discs to recess them slightly.

 

 

 

I also used sheet styrene for the pentagon shaped plates on the top of each wing.  They are modeled on the wings in the FM F-20 kit, but since I'm using the more accurate AFV wings, they needed to be added.  I also used sheet styrene for the fillet on the side of the wingtip missile rails as well as the bracket that connects the fillet to the rail.

 

 

I used a small drill bit and exacto blade to open the air scoops at the base of boths sides of the rudder.

 

 

The F-20 had some sort of sight glass on both sides of the rear fuselage. In photos, it appeared to have a green background and red label.  I wasn't happy with my first attempt to replicate this, so I cut out a section of the fuselage and inserted a section of sheet styrene to replace it.  I first drilled a hole through the sheet for the sight glass and glued in another piece of sheet styrene in the back. I then painted the area green and used a small red decal to represent the label in the sight glass.  I then filled this hole with UV light curing glue and sanded it down flush with the fuselage.

You can also see I glued in a patch of sheet styrene in the lower rear section of the fuselage.  This is due to the fact that I had to thin down this section to the point that the plastic was too thin to scribe.  The black areas are rubberized CA that I used for filler.  

 

 

[Drew T.]

I had planned to use the KASL exhaust, as the kit one looks horrible.  However, I also happened to have the Wolfpack exhaust as well.  I liked the Wolfpack exhaust better, but it didn't include the front section of the exhaust like the KASL set.  The OD between the two exhaust sets didn't quite match, but the middle section from the FM kit was a pretty close match.  So what I ended up with is the Wolfpack exhaust (blue-gray section), the FM kit middle section of the exhaust (gray section), and the KASL front section of the exhaust (tan section).

I also opened up the vent on each side of the fuselage just ahead of the engine.  The kit shows it as just a depression, but it should be open from the front.

 

 

I had to graft on the wing strakes from the FM F-20 kit onto the AFV F-5 kit since they are shaped differently between the two planes.  Since the wing of the FM kit is overly thick, the strakes had to be thinned down to match up with the AFV wings.  I used sheet styrene to replicate the raised panel under the strakes where they meet the main wing section.  I also used sheet styrene for the small raised bump around the front-bottom section of the leading edge of the wing.

 

 

The fairing under the rear section of the fuselage of the FM kit did not look accurate based on my reference photos, especially the tail section of the fairing.  I reshaped the front section of the fairing by sanding it down to a more accurate shape.  The rear section was made from scratch with strip styrene.  The small side sections were also reshaped using strip styrene.

 

 

 

That's all I have for now.  Next step is to start the long process of spraying Mr Surfacer primer to find all the mistakes and rough spots.  Once those are found and fixed, I can move on to painting!

 

Drew

[Drifterdon]

Amazing work Drew.  Makes my old Monogram F-20's pale in comparison.

[Drew T.]

Thanks!  I have an old nearly completed Monogram F-20 as well.  Monogram actually got the shape more accurate than Freedom Model, but the detail is not nearly as nice.

[A-10 LOADER]

Excellent work on all the small details as usual Drew, looking good.

Steve

[Drew T.]

On 1/22/2025 at 9:24 AM, A-10 LOADER said:

Excellent work on all the small details as usual Drew, looking good.

Steve

 

Thanks Steve!  I’ve made a little more progress on this project.  I decided to get the landing gear and gear bays assembled and painted before painting the red and white scheme.  The landing gear in the AFV kit is ok, but could definitely use some detailing, especially the nose gear.  I’m surprised no one has come out with detailed 3D printed replacements, as the nose gear in particular is pretty complex and the F-5E is a pretty popular subject.  I did use the forward fork of the nose gear from the FM kit, but the rest is from AFV.  I’m also using Reskit’s wheels.  They look great, but beware that the nose wheel is slightly larger than the AFV wheel, so I had to do some trimming on the nose gear strut to get the wheel to fit. 

 

 

I also added some detail to the nose gear bay doors, especially the rear nose gear door, as the AFV kit has no detail whatsoever here.

 

 

The landing gear was painted with Tamiya LP-11 silver, as it’s a good approximation for the silver finish on the real F-20/F-5 landing gear.  The yellow/black markings on the main gear bays were cobbled together from three Anyz decals.   Also, before I painted these areas, I painted the whole exterior of the model with Tamiya 1500 white Mr. Surfacer to find and fix flaws from construction.  This still needs to be sanded with 2000 grit sandpaper in preparation for the glossy red and white paint scheme.  The white primer is a necessity when the paint scheme will be white and bright red!

 

 

 

I temporarily glued the landing gear to spue gates for painting. 

 

 

The exhaust area was painted Alclad dark aluminum and magnesium. All these metallic areas were given a wash of Tamiya black enamel wash to highlight detail.

 

 

That’s all I have for now.  Next step is to get to the paint barn!  Thanks for looking!

[A-10 LOADER]

Excellent progress Drew. Looking forward to seeing her emerge from the spray booth.

Steve

[Ikon]

Fantastic build! The level of detail going in is bogling!

[Drew T.]

On 2/24/2025 at 3:53 PM, A-10 LOADER said:

Excellent progress Drew. Looking forward to seeing her emerge from the spray booth.

Steve

 

On 2/26/2025 at 8:28 PM, Ikon said:

Fantastic build! The level of detail going in is bogling!

 

Thanks as always guys!

[lgl007]

WOW... truly impressive!

 

-Greg

[Ichitoe]

Solid work you’re doing! Looking forward to the rest of your build. 

[Drew T.]

On 2/28/2025 at 9:59 PM, Ichitoe said:

Solid work you’re doing! Looking forward to the rest of your build. 

Thanks!  

 

Just a quick preview of the paint job.  I have the red and white sprayed.  Paint is Mr. Color GX-1 white and GX-3 red.  The F-20 designation on the fin and the serial number are masks.  I still need to mask and spray the black pinstriping between the red and white along the fuselage which will be a real pain.   

 

 

This thing looks like a flying billboard for Coca-Cola in bright red and white!  🤣