2. DESIGN CONCEPT OF P19 SHORTY

The development of the P19 Shorty trailer represents a continuation of Polydrops' commitment to energy efficiency and accessible sustainable transportation solutions. As a successor to the P17 Essential trailer, the P19 Shorty inherits the core principles of affordability and energy efficiency.

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The design of the P19 Shorty trailer is optimized for energy efficiency through two key strategies. Firstly, the trailer utilizes the construction principles of passive houses to achieve a highly insulated cabin through the use of seamless structural rigid insulation. This eliminates thermal bridges and enhances the overall insulation of the trailer.

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Secondly, the P19 Shorty trailer utilizes state-of-the-art Computational Fluid Dynamics (CFD) technologies and recent advancements in fluid dynamics to minimize air drag and enhance energy efficiency while towing. This represents a departure from traditional approaches in the RV industry, which often rely on large battery packs to mitigate range loss. By utilizing CFD, Polydrops seeks to demonstrate the potential for enhanced energy efficiency through optimized design, without sacrificing usability or increasing the cost of ownership.

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The present study focuses on the impact of CFD on the design of the P19 Shorty trailer, with the aim of contributing to the ongoing development of sustainable and energy-efficient transportation solutions.

3. ANALYSIS METHOD

For this analysis, a teardrop trailer with commonly accepted aerodynamic design was selected as a reference for comparison. The design was inspired by sub-sonic airfoil, commonly found in most civil airplanes, and its boundaries were carefully matched with those of the P19 Shorty to ensure an equivalent frontal projected area and ground clearance. The trailers were then subjected to air drag measurement in a virtual air tunnel at a speed of 55 mph, with the results recorded in units of Newton, when attached to a Tesla Model 3.

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Dimension of virtual air tunnel: 14' x 99' x 13' (W x L x H)

Speed of air: 55mph
 

ENTRY 1: Virtual Teardrop trailer
ENTRY 2: Polydrops P19 Shorty 

5. CONCLUSION

The results of the tests demonstrate the aerodynamic superiority of the P19 Shorty, with a 38% reduction in air drag compared to conventional teardrop shape trailers. This improvement leads to a minimized range loss for electric vehicle owners. However, the towing of a P19 Shorty results in a 39% increase in air drag for the Model 3, similar to the air drag experienced by the Model 3 when traveling alone at 70 mph compared to when towing the P19 Shorty at 60 mph.

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The results of the CFD analysis performed by Polydrops indicate that there is potential for further optimization in the aerodynamics of recreational vehicles (RVs). The common assumption that the teardrop shape is the most aerodynamic is based on research from 1922 by Wolfgang Klemperer, but since then, advancements in aerodynamic and fluidic dynamics research have led to new and innovative shapes in modern aircraft and vehicles. The aerodynamic design of a product is dependent on its intended use. Trailers are not meant to fly and prioritize minimizing air separation and lift loss. Instead, they are designed to be towed by a vehicle. Given the unique requirements of RVs, dedicated aerodynamic studies are necessary to optimize their design.