SEAWINGS is proud to feature this exclusive kit-build review by one of the modeling world's foremost vacform kit 'Modeling Masters', Richard Staszak - back in 1984 I came across what is for me one of the all-time modeling 'bibles' entitled 'Building and Improving Vacuum-Formed Model Aircraft' written by Richard and published by Kalmbach Publishing, and I read it from cover to cover. It guided me through all my early vacforms, the first being the Blackburn Perth flying boat featured in the Model Gallery section of this site, and it was my FIRST vac-form. This was built with no problems, utilising the methods Richard outlined in the book. I still have it on my bookshelf today and will never part with it. If you see a copy, grab it - it will never be bettered. My grateful thanks goes to Richard, who as you can see, is still  'The Master'

Thanks, Richard.

Guest review by Richard Staszak

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The Combat Model Company has produced a large range of models (aircraft and ships) in various scales using basic vacuform (VF) procedures. In general, these kits are relatively crude and require considerable modeler experience to produce a quality miniature. The positive side of the Combat Models story is that they have generally produced kits of subjects unobtainable in any other form or scale. In particular, Combat has provided a series of 1/72nd scale flying boats, most of which I have in my to be built collection.  

                                                             The Kit

The first of these I have built is the Martin Mars. The basic kit is packed in a sturdy card box and consists of 28 major parts and a package of clear plastic disks to be used for the multiple small windows that appear on the fuselage. ( I discarded these and used a liquid glass product.) A very basic 1/72nd scale of three views in semi-blueprint form is provided which also shows the beaching gear configuration. Basic construction techniques are also presented in generic form. There are no propellers, wheels , decals or marking data included. As a result the model builder will need to supply his own set of reference data as well as the missing components and details.

I checked the basic kit parts against the kit plans and concluded that the model represents a JRM-1 rather than the later JRM-2 version. The JRM-2 being somewhat longer in length.  


Before starting to remove components from the backing sheet I recommend that the reference data be used to determine what panel and control surface lines need to be added/deleted or re-scribed to improve the overall appearance of the kit parts. Many of the basic panel lines and access doors are missing from the parts.  

Construction Advice

In building the model I noted the following special effort areas:

* The Fuselage nose appears to be too blunt and I installed a wooden block to allow for re-profiling. Wooden blocks were also installed inside the fuselage to support mounting of the beaching gear assemblies.

*Since there is no clear cockpit canopy component supplied I removed the corresponding area from the assembled fuselage and used a push through method to form a clear section replacing the cutout area. It was necessary to scratch build the entire cockpit interior using data from the reference information.

*There is a decided depression in the starboard side of the fuselage that will need interior reinforcement together with several external coats of body putty.

* The rear of the fuselage float area is not symmetrical as the starboard half is about .125 inches out of contour from the port side. I chose not to correct this problem as it would require a major effort and once the model was completed the underside shape difference would not be noticeable.

*The wing sections need reinforcement at the wing tips and wood blocks were installed and re-contoured to match my reference data.

*Because of the large wing span on the model a plastic wing spare built up from multiple sections from the kit backing sheet. The dimensions or the spar were taken from the kit plans. A corresponding wing box was made and installed in the fuselage which would provide the required wing mounting strength and alignment.

*Upon installation of the port wing I noted that the outboard panel drooped rather then continued the normal wing dihedral. (I may have over sanded this section to cause the problem.) I found it necessary to cut the wing section underside and wedge it up with plastic sheet to continue the correct dihedral.

* The rear of each engine nacelle is molded integral with the wing sections and were found to somewhat distorted and required rebuilding. Before installing the cowling fronts. In particular, the inner nacelle of the port wing was oversize and required removal and build-up of a new section using scrap plastic and body putty.

*The outboard wing floats, when assembled, displayed keel dimensions that did not match the kit plans. I used body putty to build up their depth in this area.

*When the assembled outboard floats and installed float pylons were offered up to the appropriate wing section the support strut lengths were noted to be incorrect causing a miss-alignment of the float. I needed to add .125 inches to one strut and remove material from the other three struts until the floats were in the correct position in height and angle relative to the fuselage.

*The fit of the wings to the fuselage is not good. The fuselage top should blend with the wing top surface. However, on this kit the fuselage top is significantly depressed. I used several coats of heavy body putty to blend the fuselage top into the wing profile.

*Accurate assembly of the stabilizer sections to the fuselage was very difficult due to the complex shape of the fuselage in the mounting area and the stabilizers have both a dihedral and a 6 degree angle of attack. An extensive cutting and fitting effort will be required to arrive at a satisfactory fit. I used a steel rod, bent to the correct dihedral angle to support the assembly.

*Detailing of the completed model will require an extensive review of all the reference material. In particular, I found it difficult to determine the exact location of the engine exhausts on the engine cowlings. After much deliberation I decided that the exhausts were on each side of the cowling in line with the wing leading edge and at the base of the engine mount. The exhausts were made from sections of plastic tubing rolled into an oval shape.

*Propellers and engines will need to be scratch built unless you have the correct set in your spares box. I had spare resin engines in my scrap box and scratched the propellers. Cast metal propellers can be purchased from Roger’s Models for about $20 American if one desires. The wheels were from the spares box and the beaching gear scratch built.  

Painting and Decals

The model was painted overall gloss Navy Blue with a small area forward of the cockpit over painted with a flat coat to provide a reduced glare for the crew. The cockpit interior was painted medium gray with red seat cushions and flat black boxes, instrument panel , center console and instrument panel cover. The beaching gear components were painted bright yellow. Propellers were flat black with yellow tips. Exhaust stains from the engines and various outlet vents on the wings were sprayed various shades of gray and black.

Decals came from the spares box with model railroad lettering used for most of the signage appearing on the aircraft. The unique Naval Air Transport Service emblem (not shown in the attached pictures) were made using Photoshop and my computer.  

And finally.......

Was the effort involved in realizing this model worth it? I would say so as I doubt that many model builders have the 1/72nd scale Mars in their build up collection. Now on to the Combat Models Tradewind.


1.Gunston, Bill; “the Mighty Mars”; Aerospace Monthly; April 1976; Vol 4, No.4; IPC Transport Press Ltd.

2. “Variant Briefing, Martin Flying-Boats, Mariner, Mars and Marlin”; Wings of Fame; Vol. 7; Aerospace Publishing Ltd.; 1997.

3. Gouldthrope, Ken; “Dan McIvor’s Mars Mission; Air & Space; October/November, 1993; Smithsonian Publication.


5. Smith, Bob; PBM Mariner in Action; Aircraft No. 74; Squadron/Signal Publication Inc. 1986.

6.Descriptive Arrangement Drawing; Bureau of Aeronautics; Navy Department; September, 1944 (author’s collection)

7. “The Gods of War: Mars Flying boat” Inflight USA; August 1994.