'Mule' deck tractors in 1/72 scale



I have only a few Verlinden kits, but my favorite of those is definitely the MD-3 'Mule' US Navy tractor. I find the simple design cute in a way that I cannot describe accurately. Quickly I found out that there are many more 1/72 Mule kits, and on this webpage I compare the various models. At the end of the page, a set of reference photos are presented, showing more variations of the APUs mounted to the Mule's rear side.



Designations    History    Verlinden    Fujimi    Testors    Maquettes Dauzie    DreamModel    PhantomModels    Hobby Master

Kit comparison    Colors    MD-3 'short' tow tractor    MD-3 with type 1 APU    MD-3 with type 2 APU    MD-3 with type 3 APU

MD-3 with type 4 APU    MD-3 with firefighting unit    MD-3 various details    Model links



Designations

My limited understanding of the vehicle's designations is that the original yellow-painted Mules were designated MD-3, MD-3A and MD-3B, and that the improved (Service Life Extension Program, SLEP) white-painted Mules are designated A/S32A-31, A/S32A-31A and A/S32A-31B. The SLEPed version can be identified easily by the widened rear of the vehicle (some 6 inches) and a sloped rear edge (like a car 'spoiler'). The Verlinden, Fujimi and Maquettes Dauzie Mules are the original version, only DreamModel offers the later wider version.

Note that there was a short period where the 'old' version was painted white, because the Navy phased out the yellow paint that contained lead (or maybe cadmium?). Judging from the occurence of both versions in Verlinden's 'Lock-on No 14: USS Forrestal' from 1991 (possibly the contents were photographed in 1990), the switch occured around that time.

All kits I've seen have single rear wheels. But I'm sure the real thing has double wheels. Possibly the 6 inch widening also has to do with the rear wheels, creating a wider track, or the use of wider tires.

Confusingly, the US Air Force also has an MD-3: "The MD-3 Generator Set is a portable unit designed to furnish AC and DC electrical power for the starting of aircraft, and for ground maintenance". It's definitely not a tractor, so the two can't be confused.




History

The Mules used to be known as MD-3s, but are now officially known as the A/S32A-31. I found a few Navy manuals with some information.

Quoting from 'Aviation Support Equipment Technician (ASE 3&2 AND ASM 3&2), Volume 1, Basics' (NAVEDTRA 103245), 1981 edition, page 6-5:

Quoting from'Aviation Support Equipment Technician (ASE 3&2 AND ASM 3&2), Volume 1, Basics' (NAVEDTRA 103245), 1981 edition, page 6-25:

Quoting from NAVAIR (Naval Air Systems Command) 19-40-44:

NAVAIR (Naval Air Systems Command) document 19-40-44 lists the following dimensions, without stating whether it's for the original design or the SLEPed version:

These measurements translate into 57.2 x 22.9 x 12.7 mm.




Verlinden

In 2000, at an IPMS-NL meeting, I obtained a Verlinden 1/72 resin scale model of the MD-3 'Mule' US Navy deck tractor. It's shown in my oldest Verlinden catalog, 'Catalog No.4' that's probably from around 1987. The box has catalog number 240 printed on the label, but 'Catalog No 4' also lists a secondary number, ACDA 72003. Later, probably after the move to the USA, the kit was listed as catalog number 2560. It was produced until at least 1994, since it was still listed in Verlinden catalog #13 from 1994-1995. Verlinden also has a fire-fighting version, kit number 267 (ACDA 72004, later 2591). The package attached to the rear of the tractor is probably the SB/TAU-2 as described above. It appears that this kit only contains one version, but not having seen the kit, I'm not 100% sure.

The photo below shows all resin parts. At the front there's the 'short' tractor in one piece. The second row shows three rear side attachments, plus five detail parts (two hitches, parking brake handle, steering wheel, hitch extension). The third row shows the front and rear wheels. Also included in the kit are dry transfers, that probably stopped working years ago. Not included is the flexible hose for the APU.

Apart from some pinhole air bubbles, I liked the model a lot. The only thing I planned to improve were the wheels, since the tires lacked profile, which is a bit awkward for such a slippery working place, plus the rear wheels should be dual wheels. I plan to use the wheels of a Fujimi Mule.

I found a short kit review in Fine Scale Modeler, December 1987 issue. It is very favourable, but has no comments on accuracy. It reports that a photo of the depicted Mule can be found in 'Super Carriers - US Naval Air Power Today' by Montbazet from 1985. I found a photo in the later 'Supercarriers - Naval air power in action' on page 26-27.

In 2021 I gathered some 30 snapshots from various YouTube videos, shown at the end of the page. The photos show both the 'short' version, and the 'long' version. The 'long' version had three types of APUs attached. Unfortunately I do not know which is which (see gas turbine versions listed above), so I called them Type 1, 2 and 3. The Verlinden APU attachment looks a lot like Type 2. For the 'short' version, a ballast plate is missing, but funnily if you would cut off the 'bumper' and rotate it 90 degrees, you're 90% done. Also, a simpler tow coupling is missing: a simple C-bracket with a pin through it.




Fujimi

Eventually I bought the Fujimi 'Deck crew set' (catalog number 35001), and this turned out to be quite a surprise. With regards to details, this injection moulded MD-3 was a near 100% copy of the Verlinden model! Of course Fujimi had to break up Verlinden's single-piece main casting into several smaller parts, but otherwise the differences were very, very small. The hood has a fold on the centerline (that I have seen in only one photo of the real thing, the rest had slightly bulged hoods), but otherwise it is identical, down to the tiniest details. The Fujimi model also has the incorrect 'rear bumper' for the short version like Verlinden, which further reinforces the impression that the kit is a copy. Alternatively, both Verlinden and Fujimi could have used the same set of drawings to create their models (I've been told that Modell Fan once had Mule drawings). On the other hand, I was quite amazed that it was possible for Fujimi to achieve the same detail level with injection moulding. Another lesson learned!

The Fujimi Mule can be built in three versions, the short version, the version with a 'Huffer' extension similar to Verlinden, and the fire-fighting version that is probably the SB/TAU-2 as described above. The first and second are also found in Verlinden #240, the last is similar to Verlinden #267.

The oldest proof of existence that I found of the Fujimi set is a 1990 catalog, but I don't have catalogs of 1987, 1988 and 1989 (it's not shown in the 1986 catalog). The MD-3 is also listed in my 1994, 1995, 1996, 1997 and 2001 Fujimi catalogs. In 2008 or 2009, the Mule tractor was included in a reissue of on Fujimi's VF-96 F-4J.




Testors

The Fujimi set was also issued by Testors in the USA, with catalog number 850, with photo box-art. Possibly it was also sold bagged, with a black and white header card based on the Fujimi box art.




Maquettes Dauzie

In 2007 I bought a Maquettes Dauzie resin 1/72 scale US Navy tow tractor (catalog number 72 006) at the IPMS-NL Nationals. The oldest reference I found so far is an August 1986 advertisement in Scale Aircraft Modeling. Compared to the Verlinden/Fujimi MD-3, it has a different unit attached to the rear side. Also included are parts to make the air starter's hose, in the shape of a piece of hose, and metal wire to wrap around it. Judging from the exhaust location on the right side, the APU is like Type 1 in the reference photo section below. However the details on the left side are of Type 2 if I am not mistaken. The same tractor was also available without the APU unit at the rear (catalog number 72 007).

The length and width of the complete vehicle are around 15% less than the Verlinden/Fujimi Mule, which makes you wonder who used the correct (or best) data. I obtained some more MD models, and the dimensional errors in them are so obvious that my trust in MD's master builder has disappeared largely. Therefore I believe the Verlinden/Fujimi Mules are more accurate.






DreamModel

In 2008, DreamModel from China issued four resin Mule kits, with photo-etch details and decals. The versions are old & new short style, and old & new long style tractors. The new style tractors have increased rear track, and slightly widened fenders to match.

0201 (old & long) 0202 (new & long) 0203 (new & short) 0204 (old & short)



PhantomModels

In 2013 PhantomModels from Moscow issued a resin Mule kit, with photo-etch details and decals (catalog number 7002). It represents the updated version with increased rear track, and slightly widened fenders to match.




Hobby Master die-cast

Hobby Master released a diecast Mule in a blister packaging. It comes in two versions: the 'US Navy Tow Tractor' (catalog number HD2002) featuring an MD-3A with two figures, and the 'US Navy Fire Tractor' (catalog number HD2003) featuring an MD-3 with the fire fighting attachment, in white and red, with two figures. It appears that the same sets were sold in cardboard boxes with a 'B' extension to the catalog number. The two versions are also sold together as 'Modern aircraft carrier diorama' (catalog number HD1002).

HD2002 HD2003 HD2002B & HD2003B HD1002



Kit comparison

I haven't assembled the Verlinden and Fujimi kits yet, but of these two the Fujimi kit seems to hold the edge. Some advantages:




Colors

Somewhere during the early nineties, the color of US Navy deck vehicles switched from yellow to white. Alex Suvorov's excellent webpage U.S. Navy Flight Deck Tractor Models claims the colors were FS 33538 Orange Yellow and FS 17875 Insignia White. Humbrol 197 and Revell 310 (both RAL 1028 matches) come quite close to the former.




MD-3 'short' tow tractor

Both 'short' MD-3s have what looks like a ballast plate attached to their back sides. They are about half the height of the tractor, with rounded top corners.

Snapshot from video SH-3A helicopters loaded with homing torpedoes are hooked up with tractors aboard
There's a ballast plate on this one too.

Snapshot from video Ready On Arrival (1966)
This MD-3 has a short and simple tow attachment on the front.

Snapshot from video SH-3A helicopters loaded with homing torpedoes are hooked up with tractors aboard
The MD-3 on the right has a long (extended) tow coupling on the rear. The one on the left has a tow coupling (different from the above) on the front.

Snapshot from video SH-3A helicopters loaded with homing torpedoes are hooked up with tractors aboard
Another 'short' Mule with a ballast plate at the rear.

Snapshot from video SH-3A helicopters loaded with homing torpedoes are hooked up with tractors aboard
The ballast plate is nicely striped on this Mule, and it has a long (extended) pintle hook on the rear.

Snapshot from video Tractor tows an aircraft S2F by tail aboard USS Randolph
Another 'short' Mule with a simple tow attachment on the front bumper. Look at the shine on those tires! The overall condition looks near-perfect too.

Snapshot from video Tractor tows an aircraft S2F by tail aboard USS Randolph
Another nicely striped ballast plate, and it has a short pintle hook on the rear.

Snapshot from video Tractor tows an aircraft S2F by tail aboard USS Randolph
This Mule looks brand new to me. In the source movie, the Enterprise looks like it's on shakedown, with only a few aircraft on board. This makes it from the early sixties.

Snapshot from video Inside The Big E



MD-3 with type 1 APU

This APU attachment is flush both on top and on the sides. The circular exhaust is positioned relatively far aft.

Snapshot from video USS Kitty Hawk '70-'71 Cruise (launch/recovery)
A reasonable rear view of the same APU attachment.

Snapshot from video Vought F-8 Crusader - The Last Gunfighter
Another partial view of the right side of the APU.

Snapshot from video US Aircraft take off from USS Coral Sea in South China Sea
A clean shot of the APU's right side. The Mule has a aircraft arrestor hook attached for some kind of cable operation.

Snapshot from video USS Kittyhawk Action - Color 1971 - F-4 A-7 RA-5 A-3 launch recovery arming Vietnam Viet Nam
I believe (based on limited data) that this is the left side of the Type 1 APU, with louvers.

Snapshot from video Air Ops - USS Kitty Hawk (CVA 63) - Gulf of Tonkin 1970-1972 (Part 1)
This back view is identical to the second photo of the Type 1.

Snapshot from video A day in the Western Pacific aboard USS Oriskany CV-34 U.S. Navy film 81104
A shot that shows some details of the rear side of the Type 1. It never seems to have the hot air unit attached to it, like the Type 2.

Snapshot from video U.S. Navy aircraft carrier flight deck safety training film "Disasters don't just happen"
Probably filmed on board the Kitty Hawk (CV-63). The Oshkosh MB-5 fire truck is also of note.

Snapshot from video Task Force 77 (1970)
Mule driver relaxing, with the rearr of two other Mules visible. Probably filmed on board the Kitty Hawk (CV-63).

Snapshot from video Task Force 77 (1970)
Mule with Type 1 APU towing an A-7. Probably filmed on board the Kitty Hawk (CV-63).

Snapshot from video Task Force 77 (1970)



MD-3 with type 2 APU (like the Verlinden model)

This APU type has the exhaust more forward compared to the type shown above, plus two smaller black circles at the 45 and 225 degree positions.

Snapshot from video United States Navy, A-7E aircraft being towed across the deck aboard Super carrier
Another one showing the 'three circles' layout of the APU's right side.

Snapshot from video Aircraft launched from flight deck of USS Constellation at Yankee Station
Looks similar to the above subversion.

Snapshot from video Air Ops - USS Kitty Hawk (CVA 63) - Gulf of Tonkin 1970-1972 (Part 1)
Another photo of the type.

Snapshot from video F-4B aircraft being launched from deck of USS Enterprise (CVAN-65) during Vietnam
As far as I know, this is the left side of the Type 2 APU.

Snapshot from video United States Navy, A-7E aircraft being towed across the deck aboard Super carrier
A slightly blurry shot of the APU's left side.

Snapshot from video Air Ops - USS Kitty Hawk (CVA 63) - Gulf of Tonkin 1970-1972 (Part 1)
A shot from the early sixties. Note relatively few markings during the initial use. The Mule at the left has its wheels painted in a different color.

Snapshot from video Inside The Big E
This is probably the same Mule as in the above shot.

Snapshot from video Inside The Big E
In this picture we see a unique detail: a long tie rod that connects the APU to the tow tractor. I'm not sure this is a standard fit.

Snapshot from video U.S. Navy aircraft carrier flight deck safety training film "Disasters don't just happen"
Great detail shot of the APU's right side.

Snapshot from video U.S. Navy aircraft carrier flight deck safety training film "Disasters don't just happen"
Interesting rear view, with some kind of attachment on the rear's top. The Mule at the rear is shown in the Type 3 APU section.

Snapshot from video Operation Saratoga (1965)
Rare photo of maintenance being performed on a Mule.

Snapshot from CVA-63 Kitty Hawk cruise book 1966-1967
This one has no rounded extension on top of the extended bumper, like many above. Instead there are some small-section beams against the rear side, plus some kind of basket.

Snapshot from video Hot Shots! - Highway to the Danger Zone
Partial view, showing an improvised basket for the air start hose.

Snapshot from video USS Midway Carrier Action - Vietnam 1965 A-4 Skyhawk A-1 Skyraider A-3 Skywarrior F-4 Phantom CVA-41
Judging from the exhaust in the extension, this is a type 2 APU, but with the side painted mostly black. Aboard USS Coral Sea (CVA-43).

Snapshot from video Reel No 1 CVA 43, HC 1 Det 43, 1st Cruise '67 68
Same carrier, same black-painted panel on the Type 2 APU.

Snapshot from video Reel No 2 CVA 43, HC 1 Det 43, 1st Cruise '67 68



MD-3 with type 3 APU

Both Mules have the APU in a 'raised' position, well above the deck of the tractor itself. The combination of the gusset in the tractor's extension and the triangular rear leg of the APU creates the trapezoid shape, that is the easiest identification feature of this version.

Snapshot from video Discovery Channel Wings - A-4 Skyhawk
 
This looks like the same APU unit to me, but now lowered and flush with the tractor. The trapezoid is accordingly lower. However it looks like the APU is wider than the tractor.

Snapshot from video Ready On Arrival (1966)
The left side also shows the trapezoid opening. Again the APU appears to be slightly wider than the tractor.

Snapshot from video Ready On Arrival (1966)
 
Is this the previous deck vehicle that carried the same APU?

Snapshot from video 'Flight deck' 1964 aircraft carrier USS Franklin D Roosevelt
A nice shot of the rear of this APU type.

Snapshot from video F-4B aircraft being launched from deck of USS Enterprise (CVAN-65) during Vietnam
 
Great side view of this MD-3 type. The APU is again wider than the tractor.

Snapshot from video F-4B aircraft being launched from deck of USS Enterprise (CVAN-65) during Vietnam
The Type 3 APU being used to start up an A-4 on board USS Saratoga.

Snapshot from video Operation Saratoga (1965)
The Type 3 APU Mule towing an A-4 on board USS Saratoga.

Snapshot from video Operation Saratoga (1965)
Apparently filmed on USS Independence, this Type 3 APU is used to start up an A-4 410. We can now see the rectangle is actually a slanted opening.

Snapshot from video U.S. Navy Aircraft Carriers Operating Off Vietnam
Another screen shot from the same movie, with the Mule in the previous photo in the background, starting Skyhawk 410.

Snapshot from video U.S. Navy Aircraft Carriers Operating Off Vietnam
Rare top view of the Type 3 APU Mule. There appears to be an additional small intake or outlet on the left top side.

Snapshot from video USS Franklin D Roosevelt CVA 42 1965 Med Cruise
This screenshots shows that the third APU type was used until 1980 or later. Of note are the white wheels with red hubs, and the white number shield.

Snapshot from video USS Nimitz CVN-68 1980 aircraft carrier & F-14 operations & capabilities



MD-3 with type 4 APU ?

There may be yet another type of APU attachment, or maybe it was a fire-fighting unit, considering it was painted red, plus what look like rolled-up fire-fighting hoses. So far only one picture has surfaced, on the USS Coral Sea tribute site (find courtesy of Jari).




MD-3 with SB/TAU-2 firefighting unit

A rare photo of the Mule in the fire-fighting role, probably filmed on board the Kitty Hawk (CV-63). These Mules were clearly also used for towing duties.

Snapshot from video Task Force 77 (1970)
 
A rather vague shot from the superstructure, also probably filmed on board the Kitty Hawk (CV-63). It is standing by next to an Oshkosh MB-5 fire truck.

Snapshot from video Task Force 77 (1970)
A rather bare yellow Mule with the SB/TAU-2 firefighting unit from the 1972-1973 timeframe, standing guard during launch operations.

Snapshot from video USS Midway Flight Operations 1972 73
 
An interesting all-red Mule with the SB/TAU-2 firefighting unit, the tank of which appears to have a slightly different tone of red. On the back something resembling a hose reel can be seen.

Snapshot from video USS Midway Flight Operations 1972 73
A rare partial view of a Mule with the SB/TAU-2 firefighting unit. It's a pity about the discoloration of the film.

Snapshot from video A day in the Western Pacific aboard USS Oriskany CV-34
 
A mostly yellow Mule with the SB/TAU-2, wheels and tank in red. It took me a while to what's behind the Mule: a crewman. I first 'saw' a red fire extuingisher :-)

Snapshot from video USS America (CVA/CV-66) 8mm Film by US Navy Pilot, LCDR Neil Holben
A partial rear view of a yellow Mule with a yellow and red SB/TAU-2 firefighting unit. Details are vague, but an additional fire extinguisher bottle is clearly visible.

Snapshot from video Strike Operations USS Coral Sea (CVA-43) - 4/26/1972
 
A yellow Mule with the SB/TAU-2 add-on in red. However the large tank is purple, a variation not seen before.

Snapshot from video VA-164 USS Hancock 1972
From the same film, an all-red fire-fighting Mule with again a purple tank.

Snapshot from video VA-164 USS Hancock 1972
 
One more all-red Mule with a purple tank. It's difficult to see, but there's a second crewman in full gear sitting on the rear, suggesting there is a seat or a bench.

Snapshot from video VA-164 USS Hancock 1972
A rear view shows that the rear crewman sits on the right-hand side.

Snapshot from video USS Hancock 70-72 Pilots
 
A low-quality screenshot, but an interesting variation: an all-red fire-fighting Mule with a yellow hood, probably a replacement part. The rear seating area appears blue-purplish.

Snapshot from video USS Ticonderoga CVA14 1967-1968
Excellent rear view of two firefighting Mules. I think we now clearly see the rear seating area. The frame on the left is a holder for a rolled-up fire hose. Its nozzle and handles are also clearly visible.

Snapshot from video A Day In The Western Pacific Aboard USS Oriskany CV-34
 
Firefighting Mule aboard USS Coral Sea CVA-43 during a deployment to Vietnam in 1971/72, in yellow with a red tank.

Cutout from Wikipedia file:F-4B VF-111 CVA-43.jpg



MD-3 various details

This is probably a Type 2 APU with an additional basket. It appears to be made from angle iron and wire mesh.

Snapshot from video The job of the EA-6B Prowler Grumman Aviation film 81802
 
A good view of the dashboard.

Snapshot from video U.S. Navy aircraft carrier flight deck safety training film "Disasters don't just happen"
Great view of the instrument panel. But what are the vertical tubes? Both Mules have them. Maybe it's to prevent tow bars from falling off - but then the driver is in the way!

Snapshot from video Landing of US Navy jet fighters on flight deck of aircraft carrier USS Franklin
 
Top side view from the cockpit of an A-3 being started. APU version is unknown. It appears no anti-skid coating is applied.

Snapshot from video USS Midway Flight Operations 1972 73
Unique view of the starter hose being pressurized, while starting an A-3. The extended tow hook on the Mule is also of interest.

Snapshot from video USS Midway Flight Operations 1972 73
 



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