Wednesday, October 18, 2006

How To Build an Astro 95 Gas Turbine Special

Astro Test Vehicles @ GM Proving Grounds, 1969.  Can you find the Turbine?

So you've finally done it. You've gone and dropped nearly $100 for an extremely rare AMT 1/25 GMC Astro 95, including that vaulted and scarce turbine engine option.

Congratulations! You've not only captured a fine kit for your building hobby, but also my jealousy. I can only wish I could afford one.

Regardless, building the kit you hold in your hands won't give you a 'perfect' replica of the Astro Turbine demonstrator built by GMC. While the majority of what follows may constitute as "nit-picking" due to my obsessive nature regarding GMC history, there are a few major areas that need correcting before assembly.

That being said, here's at least a little bit of "detail oriented" specifics for how to "turbine" your rig.



1969 GMC Astro 95 Turbine

We may as well start here. Luckily, for the most part, any AMT Astro kit has a relatively early Astro cab that will work with this subject.

However, there are a few matters that will need correcting. Perhaps the most obvious are the "bus-type" mirrors that mount on the front corners of the cab, as opposed to the doors. Additionally, the "L"-shaped grab rails need to be replaced by a short, diagonal rail that runs from behind the front doors to slightly above the sleeper storage compartment.

Also worth noting are the long, bullet-style cab markers, and two individual train-type air horns on top of the cab.

Do note that the grille insert differs from stock Astros in that it has a vertical and horizontal pattern. More information relevant to the grille is given below.

The original issue of the Astro kit sported cover art that, in virtually all regards, was the Astro Turbine. A white cab, adorned with red wrap-around stripes that sandwiched a blue strip, is in fact the paint scheme GMC used on this particular truck.

What isn't shown, however, is a pseudo-grille section that was painted just above the actual grille opening. Throughout its 18-year production run, the physical grille opening on the Astro's cab was never enlarged, and the Turbine was no exception. GMC simply made the grille appear larger by using a painted section that matched the pattern used in the truck's custom grille.

And to further ease your painting woes, the remainder of the truck's chassis equipment - including battery boxes, steps, fuel tanks, suspension, and even wheels, were all painted a matching white. The front bumper, however, was chromed, as is the one included within the kit.

The Turbine had some minute ornamentation changes, that, if you're anal to no end for authenticity, you may want to consider applying to your rig.

The first - and most notable - is what to do with that "GMC" script on the front of the tractor. While stock Astros sported this on the metal header between the grille and the bottom of the windshield, the Turbine had this logo moved inside the grille. Position it as high within the grille as possible.

Astro Turbine Nameplate

Secondly, GMC modified the door nameplates. While normally they consisted of a large 'GMC' followed by a small "Astro 95" underneath, the Turbine changed the latter to read "Astro Turbine". Whether or not this detail is actually applicable, due to the scale size of the nameplate, is a debatable matter.

Finally, like all GM test vehicles, the Astro Turbine sported some corporate insignia just aft of the cab doors. "GMC TRUCKS" is spelled out, with a small box below it reading "GENERAL MOTORS CORPORATION". On the sleeper storage door, "ENGINEERING" is scripted in a similar font to the "TRUCKS" above, with a smaller "PONTIAC, MI" placed below that.

While my eyes may deceive me, AMT's Astro kit represents a dual-axled tractor sporting a short wheelbase.

And while I don't have exact dimensional data for the Turbine, the photos I do have show a significant distance between the cab and the front of the trailer. Perhaps a 1/2" stretch of the frame rails would be in order to give an approximately correct look.

Another major error is with the truck's rear suspension. AMT provides the Astro with a walking-beam dual axle set-up, when, in fact, the Turbine was equipped with the "Astro-Aire" suspension.

At the time a relatively new design for GMC, this air-suspension system is better represented by the one included in AMT's GMC General or Chevrolet Bison kits. Consider swapping the former out for the latter - which may be a bit of work.

Note too the side-mounted accessories. There are no rear-mounted battery boxes, only small boxes encased with cab steps. Additionally, the Turbine does not sport the cylindrical fuel tanks, but a modified rectangular format. Perhaps the best bet to model these would be to fill in the notched step on the tanks AMT includes.

So what's the use of making a Astro Turbine look-alike if there's not actually a turbine under the cab? Absolutely none, if you ask me. I try to avoid curb-sides unless I'm extremely lazy.

Thus brings up a big issue. "What in the hell color do I paint the engine?"

While I trust the accuracy of the AMT of the past, I'm going to have to call "shenanigans" on this kit. The box illustration claims the motor included is the GT-404. As far as my records show, this particular Astro used the GT-309. It wasn't until the mid 1970s that an Astro SS was equipped with a GT-404, and sported a completely different paint scheme.

To date, the only images I have of the GT-309 are completely in two colors - black and white. While this is great for detail specifics, it doesn't allow for discernation of pigmentation.

That said, there are two routes to take with this:

  • Fire Red: Personally, I've only seen one GM gas turbine installed in a vehicle, and that was within Firebird I. This engine, the unrelated GT-302, was painted red, which also seems to match what AMT has depicted on the side of the box.

  • Detroit Diesel Green: The Astro Turbine was built sometime around 1970. What also happened that year was development of the GT-309, as well as all future commercial and industrial gas turbine development work, was sent from the GM Research labs to Detroit Diesel Allison (DDA). I've also seen a photo of a later GT-404 that was painted in DDA's infamous sage green. Subsequently, it could be argued that it would be an appropriate hue for the body.

You may be tempted to paint some additional metallic colors abound on the round sides of the engine, which are it's regenerative discs. In actuality, DDA was quite lazy, and painted the entire engine this color. Feel free, however, to detail the starter and control mechanisms on top of the engine in various shades of metal.

Also note the enlarged exhaust stacks. Unlike most trucks, these stacks were not chromed; nor were they even metallic in color. These were entirely painted white, in an attempt to call attention to the clean-burning nature of the turbine powerplant.

Like many of GM's dedicated show trucks of that era (ummm...the Astro and the Turbo Titan III, I suppose...), the Astro Turbine had it's own trailer, used both for display and for loaded testing.

Should you want to construct this for a complete display, finding a standard US-style box trailer should provide you a fine baseline for construction. This was painted silver, and had a wild red, white, and blue stripe wrapping around the sides of the van.

Special thanks go to Frederic Brede for providing the majority of these images.


Anonymous Anonymous said...

I have been researching Gas-Turbine Trucks for a long time but never been able to track down any information on the Internet on the GMC Astro Gas-Turbine Truck. I would like to know more about this truck

11/26/2006 8:31 PM  
Blogger GMTMan said...

Well, I'd love to talk to you more, Anonymous; however it's hard to since you didn't leave any contact information!

Feel free to drop me a line to chat about it.

12/20/2006 12:00 PM  

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