Modeling Hamilton Standard Counterweight Propeller

In the previous post I modeled the blade of Hamilton Standard Constant Speed propeller, which was used in the SBD-1, -2 and -3. The Douglas factory mounted on the hub of this propeller a small spinner (Figure 53‑1a):

Figure 53-1 The Hamilton Standard Constant Speed propeller (used in the SBD-1, SBD-2 and SBD-3)

It seems that during the service of these aircraft, the ground crew often removed this spinner. It exposed the propeller pitch control mechanism (Figure 53‑1b). There are many photos of the SBD-2 and SBD-3 without spinners, thus I decided that I had also to model this “bare” variant.

Modeling Propeller Blades

The SBD Dauntless used two types of the Hamilton Standard propellers:

• Hamilton Standard Constant Speed (counterweight propeller) used in the earlier Dauntless versions (SBD-1 … SBD-3). The blades of this propeller had smaller tips (Figure 52‑1a);
• Hamilton Standard Hydromatic used in the later Dauntless versions (SBD-4 … SBD-6). The blades of this propeller had larger tips (Figure 52‑1b):

Figure 52-1 The Hamilton Standard propeller blades, used in the SBD Dauntless

These two blades had different shapes. In this post I will recreate the earlier version, which was used in the SBD-1 .. -3 (Figure 52‑1a). Several posts later I will modify its copy to obtain the later model of the blade, as used in the SBD-4 .. -6 (Figure 52‑1b).

Cockpit Canopy Details

Before I start forming the frames of the Dauntless canopy (which I created in the previous post), I had to conduct yet another verification of its shape. I placed the canopy rails on the cockpit sides, and verified if they fit the corresponding canopy segments. First I tested the rails of the pilot’s canopy (Figure 51‑1a):

Figure 51-1 Tracing the rails of the pilot’s canopy

They were formed from open-profile beams (Figure 51‑1b). Why these rails are such an important test tool? Because they always have to be parallel to the fuselage centerline! It sounds obvious, but it can reveal various unexpected errors in the canopy shapes.

Forming the Cockpit Canopy

Like many contemporary designs, the SBD had a long, segmented (“greenhouse”) cockpit canopy. In this post I will show you how I recreated it in my model. I will begin with pilot’s canopy, then continue by creating the three next transparent segments.

I formed the pilot’s canopy by extruding the windscreen rear edge (Figure 50‑1). (I formed this windscreen earlier, it is described in this post). The high-resolution reference photo was a significant help in precise determining its size and shape:

Figure 50-1 Forming the pilot’s canopy

Generally, the canopy shape in the SBD is quite simple. The tricky part was that each of its segments slides into the previous one. (Oh, well, the pilot’s canopy slides to the rear, but it does not matter in this case). This means that there were clearances between each pair of neighbor canopies that permitted such movements. If I made them too small or too wide, the last (fourth) canopy segment would not fit into cockpit rear border (i.e. the first tail bulkhead)! In such a case I would have to adjust back all the canopy segments. Well, I will do my best to avoid such error.