Like most websites Airfix Model World uses cookies. We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we'll assume that you are happy to receive all cookies on Airfix Model World website. However, if you would like to, you can change your cookie settings at any time. Find out more




Brian Wakeman gets a taste of modern stealth fighters with Hobby Boss’ impressive YF-23

In the late 1980s and early 1990s, the US Air Force’s Advanced Tactical Fighter (ATF) programme was the ‘big ticket’ event for aircraft manufacturers, and culminated in a fly-off between Lockheed’s YF-22 and Northrop’s YF-23.
The latter was the competition’s unlucky loser, despite combining stealthy features (and allegedly superior speed) with a futuristic, arguably ‘sci-fi’ configuration; sharply angled ‘ruddervators’ replaced traditional horizontal and vertical control surfaces. This was matched with sinuous intakes, and forward fuselage chines that seemed to derive much from the SR-71 Blackbird, to produce a truly eye-catching design. I was lucky enough to see both of Northrop’s Prototype Air Vehicles (PAVs) at NASA’s Dryden Flight Research storage facility in 1999, with PAV-1/87-0800 and PAV-2/87-0801 sitting forlornly behind the facility, which is part of the sprawling Edwards Air Force Base complex.

Futuristic shape
What might not be apparent at first is this jet’s huge size; it was considerably bigger than the F-15 Eagle it was designed to replace, and even larger than the rival YF-22, and this was one aspect of Hobby Boss’ kit that was apparent immediately. Excitement grew as the six styrene runners, which held a total of 95 well-moulded parts, were inspected; the decals looked promising, but were for a notional in-service aircraft (see panel). Assembly commenced within the confines of the well-appointed cockpit, although it’s accuracy couldn’t be ascertained due to a lack of reference photos.

The cockpit breakdown was conventional, although the authenticity was debatable, as access would certainly have been difficult…

However, Hobby Boss captured the appearance of the type’s ACES II ejection seat faithfully, but omitted the pair of lap straps…this wasn’t an issue as the intent was to depict a test pilot in situ. The basic interior colours comprised Lifecolor UA033 Dark Gull Grey and UA735 Deep Cockpit, before the dials and switches were picked out in various colours.

…despite this, Hobby Boss presented a busy ‘office’ for its prototype jet, although one may wish to replace the kit’s ACES II ejection seat with an aftermarket item.

There then followed a pleasant hour’s modelling to assemble the intake trunking, which was treated with matt white, along with the wheel bays. The latter received Xtracolor X141 Insignia White as a base layer; once this had dried fully, a wash was applied via a fine brush, loaded with heavily diluted Adam Wilder NL02 Deep Shadow Wash (, to highlight detail and add depth.

Lifecolor’s LC01 Matt White was sprayed into the inlet ducts, although when inserted into the fuselage little could be seen.

Time and care was needed for the front and mainwheel bays, as they were complex assemblies and required careful alignment.

To add depth to the wheel bays and inner doors, a wash of Wilder’s NL02 Deep Shadow was ideal.

Wayward markings
At first glance, Hobby Boss’ decals appeared acceptable, even if they were for a completely fictitious F-23A airframe (as there were considerable differences between the prototype and intended pre-production designs). It was therefore disappointing when it was realised the lettering on the unit insignia and ejection seat warning triangles was completely illegible, with no attempt made to form actual characters. Similarly, the ‘No Step’ labels were far too large, and there was a lack of basic warning outlines.

Next came the pair of engine ‘boxes’, which represented the YF-23’s exhausts, although there was minimal nozzle detail. This was perhaps understandable, as the powerplants (Pratt & Whitney YF-119 in PAV-1 and General Electric YF-120 in PAV-2) were removed swiftly from the prototypes once the fly-off competition was completed. After a grey primer, these received Humbrol 53 Gunmetal and were added to the upper fuselage half.

The box-like features for the engine nozzles were rather crude, with just a hint of turbofan detail, but as they were buried in the nacelles, most would be hidden from view.

It was deemed prudent to number the engine box outlets, as outwardly they looked identical and could easily have been transposed.

This was a very simple model to make and most of the fuselage was assembled in just a few days. When attaching the wings, it’s advisable to employ cyanoacrylate (CA) adhesive along the butt join, as the tabs were rather short. Fortunately, the fit was excellent, with just a small gap noted, but this was eradicated with a modicum of filler. It was here that perhaps the biggest let-down occurred, as Hobby Boss elected not to incorporate an open weapons bay. If it had, it would have been able to carry two examples each of AIM-120A AMRAAM and AIM-9M Sidewinder air-to-air missiles (the F-23A would have featured a different configuration with two bays).

Mr.Hobby’s Mr.Cement ( was perfect for joining the wing halves. The clamps were useful for such a large component, to ensure a good join.

While the fit was generally good, and the aim was for a filler-free build, one or two seams still required attention, although these were addressed with CA and Deluxe Material’s Perfect Plastic Putty (

The unusual ruddervators followed the same design policy as the wings, being supplied as large two-piece sub-assemblies, which were canted outwards at 45° and added much character to the airframe. Thankfully, a test-fit revealed these could be painted and decaled separately to the main fuselage.

Revolutionary fighter
Being a prototype, the YF-23 featured a real hotch-potch of equipment, and the landing gear was a mix of F/A-18 Hornet main legs, with the nose unit from an F-15 Eagle, and this was depicted faithfully in the styrene. However, due to the fragility of the plastic, it was decided to fit Scale Aircraft Conversions’ white metal landing gear (48265) instead (, and these accepted the model’s weight without any distortion. Well-defined wheels and tyres, the latter featuring a moulded ‘flat’ to represent an aircraft on the ground, added to the overall realism.

The instructions suggested the undercarriage legs should be positioned at an early stage, but for those wanting to attach these later, small sections of styrene must be removed…consequently, on this build, SAC’s aftermarket items were filed slightly.

A number of small moulding flaws were noted on the upper fuselage, but these were remedied easily with a sharp scalpel blade and a few swipes of a sanding stick. As modellers have come to expect from Hobby Boss, panel line detail was incredibly restrained and the type’s sinuous curves were captured accurately. One aspect of the airframe that drew attention was the apparent lack of Radar-Absorbent Material (RAM ) panelling, a feature very prevalent on production F-22As and F-35s. While this may have been due to the YF-23 being a prototype, it also simplified the overall painting process. The hardest task, though, was to hand-paint the ceramic tile on the exhaust trough, and for this patience-testing aspect, a random mix of Citadel silver, bronze and copper, all diluted with Lifecolor thinner, worked well.

Small imperfections in the fuselage surface were highlighted with a lead pencil, before being removed with a sharp scalpel blade and/or sanding.

Perfect prototypes
Although Hobby Boss didn’t include markings for either PAV-1 or PAV-2, thankfully Caracal Models has stepped in with a superb sheet, YF-23 Prototypes (CD48048), which supplies all necessary insignia, stencils and logos. PAV-1, also known as the ‘Black Widow’ due to its overall FS 36118 Medium Gunship Gray livery, and PAV-2 the ‘Gray Ghost’ in standard tactical FS 36375 Light Compass Ghost Gray and FS 36320 Dark Compass Ghost Gray both feature. There’s even the hourglass Black Widow symbol that adorned PAV-1 for a short period, along with the correct pilot and crew chief names for each prototype. Register and opacity were excellent, with the Northrop company labels notable for their refinement. Visit: for more details.

Air superiority
As mentioned previously, the decals offered a notional 1st Fighter Wing jet, based at Langley, Virginia, but these were poor, with unintelligible lettering on the ejection seat warning triangles and unit insignia. Thankfully, Caracal Models came to the rescue with a bespoke sheet for the YF-23 (see panel). At this point, a light misting of Humbrol 165 Medium Sea Grey, applied directly from a ‘rattle’ can, acted as a suitable primer.
Having such a large working palette to play with, extra interest was the name of the game. From the start, it was decided to portray the aircraft as it appeared at the end of the trials programme, with a weathered, somewhat scruffy finish, after spending its admittedly short flying career flying in the skies over a harsh desert environment.

If using decorator’s masking tape, it is best to ‘de-tack’ it by sticking it to a surface a couple of times before applying it to the model (or use low-tack alternatives such as Tamiya’s).

A fine HB pencil set the camouflage boundaries, including the underside (based on photo references). So, having masked all the orifices, the lighter grey was applied via a Badger 150 airbrush, with well-diluted Lifecolor UA026 Light Compass Grey being a perfect match. Once this had cured, UA027 Dark Compass Grey was applied freehand. To create a rather patch-work appearance, random greys were added around panel lines and the centres, breaking up the monotone appearance of the model. COM-ART’s 21031 Blue-Grey Smoke ( was misted carefully over well-trodden areas until the desired effect (compared to photographs) was achieved. After the paint had dried fully, a piece of used 1,200-grade Micro-Mesh cloth eliminated any small blemishes. Humbrol’s water-soluble Clear varnish then sealed the model, in preparation for the decaling, with Caracal’s markings settling without issue.

After months under California’s harsh sun, the upper surfaces of PAV-2 exhibited a heavily bleached appearance, and Lifecolor’s Light and Dark Compass Grey hues were an excellent match, with minimal tonal difference between the two.

While the kit’s decals were a disappointment, Caracal’s aftermarket alternatives were a delight, and these settled well over the gloss surface without any silvering.

After the camouflage colours and decals had been applied, the masking tape was removed gingerly, to reveal the previously painted multi-hued exhaust troughs.

The final weathering steps involved Adam Wilder’s Nitro-Line NL19 Grey-Brown Filter, which was applied to the panel lines, and a hand-painted coat of Tensocrom TSC207 Smoke over the engine troughs. COM-ART’s 21021 Fertile Soil and 10141 Burnt Umber provided the streaking from the under-fuselage vents on the underside. Finally, a mix of Xtracrylix clear varnishes provided the perfect surface finish, with a 9:1 ratio of XA1F Flat Matt and XA1S Satin airbrushed onto the upper surfaces, and an equal blend of the two for the undersides. A dusting of Lifecolor PG106 Damp Dust pigment on the inner wings and around the rear fuselage completed the build.

As an alternative to diluted oils for panel washes, a Wilder’s filter was employed instead, and disrupted the otherwise monotone appearance of this ‘grey jet’.

Hobby Boss’ cockpit coaming was featureless, so scratch-built details were added to create interest, before receiving matt black acrylic.

Each modeller has a favoured varnish for their final finish; I have found Xtracrylix products to be easy to use, and with mixing, multiple sheens are possible.

Replicating the YF-23’s heavily stained undersides was a challenge, but COM-ART’s acrylics were ideal. They needed shaking well before use, and despite being intended for model railway enthusiasts, they are equally applicable for aircraft modellers.

The ‘beaver tail’ sections were left until the very end, and these received Humbrol’s Metalcote, before being buffed to a suitable lustre.

On a final note
Hobby Boss’ YF-23 does what it says on the box, in that it builds into good replica of the prototype airframe. However, it fails to provide any decals for either PAV-1 or -2, and lacks an open weapons bay (and associated missiles), let alone dropped flaps or leading-edge slats. All-in-all though, it’s a behemoth of a model and somewhere down the line a ‘Black Widow’ may appear on this modeller’s workbench. For those who aren’t purists and enjoy ‘what-if’ projects, then how about an F-23A in modern-day metallic greys of the vaunted F-22A flying from Holloman, Hickam, Langley or Elmendorf? Hmmm…now there’s a thought!

Posted in Features


Our Instant Issue Service sends you an email whenever a new issue of Airfix Model World is out. SAVE ON QUEUES - FREE P&P