Jun. 30, 2025
Hardware
In the realm of airflow management, the design of duct corners plays a key role in the efficiency and functionality of ventilation, HVAC systems, and wind tunnels. When air is forced to make a sharp turn, as is often required in ductwork, it encounters increased hydraulic resistance, leading to higher pressure losses and turbulence. This not only compromises the system’s efficiency by demanding more energy to maintain airflow but also impacts the structural integrity of the ductwork due to the uneven pressures exerted by turbulent flows.
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This is where turning vanes, also known as corner vanes or guiding vanes, come into play (Fig.1). Designed to be installed within the corners, duct corner vanes allow the air to navigate the turn with minimal resistance, effectively reducing pressure losses and mitigating turbulence without the need for the additional space that smooth radius-bends demand. This makes turning vanes an ideal solution for managing airflow efficiently in a compact space.
The traditional solution to overcome the mentioned harmful phenomena of increased turbulence, pressure loss and noise in a steeply curved duct is to design radial duct elbows (Fig.2 and Fig.4, case 2). These elbows, while effective in some mitigation of turbulence, noise, and pressure losses (which are common in a sharp bend as seen in Fig.4, case 1), have their own set of problems.
Several traditional ventilation ductworks with a turn made of smoothly curved sheet metal with bent flow directors is presented in Fig.2 on the left. The picture represents few examples of standard variants commonly used in HVAC ducts, e.g. compliant with DW144 ductwork standards.
Such duct solutions are common and cost-effective for small applications in civil engineering, small business and low-power HVAC systems where energy cost is not a significant factor. However, this design is not a good solution for ventilation and cooling systems in medium and large scale and high-capacity power generation, metallurgy, turbomachinery, heat exchangers, waste heat recovery and modern green and renewable energy applications where hydraulic efficiency and energy savings are a must.
However, there is no need to build a custom non-standard duct every time the energy consumption of a hydraulic network needs to be optimized to perfection. The same Figure 2 on the right shows a variant of Tunnel Tech’s diagonal guiding vane section, which is energy efficient, low noise and low turbulence, while meeting industry standards for HVAC systems, but also can be used in large-scale and high-power industrial use cases. An example of a large-scale facility where the diagonal turning vane section can be easily integrated is shown in Fig.3.
For comparison of different turning corner designs, the pressure drops (ΔP) and CFD-simulated flow patterns are given in the Fig.4 below. The inlet airflow velocity of 20 m/s and 2×2 m square duct were chosen as a demonstrational example. The speed range of 20 m/s was chosen for demonstration purposes, since normally professional-grade vertical wind tunnels for indoor skydiving operate most of the time in modes, whereby the flow velocity in the rotating section varies in between 10 and 30 m/s. CFD-calculations were performed for 1 standard atmosphere at 20 C and zero air humidity with a compressible gas and an adiabatic wall with a roughness of 250 µm. The mesh of 6 to 10 mln. cells per domain was used. Flat Inlet profile and 2% turbulence were applied at the inlet boundary. Turbulence was treated using k-ε model.
NB! Please note that the illustrations shown in Fig.4 are particular examples, presented solely for the purpose of illustrating the operating principles and comparing few types of rotary corner sections. These cases cannot be construed as general for absolutely every use case. For every real ventilation system or other hydraulic network, specific hydraulic parameters, duct size and shape, roughness and structural irregularities, flow inhomogeneities and exact physical gas parameters must be taken into account for every computational point. You can order such a calculation for a specific system by contacting us.
The following design cases are described:
The most significant problem of the round-curved ducts with small number of simple bent plate separators (or without guiding vanes at all) is the pressure and velocity distribution pattern at the turning section exit (Fig.4, case 2, see the outlet cross-section). This pattern shows that the velocity will increase from the outer wall to inner wall of each flow subdomain, leading to nonuniform flow, big turbulence and noise. The smaller the turn radius, the greater is the possibility of flow separation, pressure and velocity field distortion, noise level and pressure drop value.
The only way to overcome these issues is a big curvature radius of such a corner section and increase in the number of air flow guiding vanes. Here comes the second problem – the increased space required to accommodate such bends and the material cost of several radial airduct spacers, sized to the duct cross-section. In large duct systems, implementing smooth radius-bends can lead to unreasonably large structures, making this approach impractical in many scenarios, especially where space is at a premium. The additional space needed is shown by the dashed lines in Fig.4, case 2 below. One must increase the height and width of each turn by minimum of ½ of the duct size. For recirculating wind tunnels it means the increase of building dimensions by several meters in each direction, what leads to higher ductwork costs and higher capital investments. In addition, each flow divider will cost the same as the duct wall.
The optimal solution for wind tunnels and industrial ventilation are turning section rotary vanes with a wing profile arranged along the diagonal as depicted in Figure 4, cases 3-5.
All CFD-pictures above correspond to the airduct corner section with 2x2m inlet at 20 m/s air flow velocity, as an example, most relevant to the indoor skydiving and low-speed subsonic wind tunnel’s use cases.
Figure 4 case 3 shows a corner section with simple guiding vanes made of thin bent metal sheets. Fig.4 case 4 is the best example of rotary vanes available from TunnelTech’s closest competitors. Both have a smaller chord length and an unoptimized airfoil shape, resulting in what appears to be residual flow non-uniformity at the section exit, greater aerodynamic resistance and air duct noise. Thin vanes made of simple bent metal sheets usually exceed the permissible noise levels even at low air speed, and an option with a thick and short profile with low chord-to-thickness ration will also have a smaller surface area, which is undesirable in applications where cooled turning vanes are used for heat transfer.
In the lower part of Figure 4 case 5, the airduct corner equipped with high-performance Tunnel Tech turning vanes (for ordering refer to the following p/n: TTE-TV-90) are shown. As can be seen from the cross-sections, the flow is more uniform in the case of properly profiled guide vanes, which leads to less pressure drop and low turbulence.
The outlet air pressure/velocity profile is also much better for Tunnel Tech’s corner sections equipped with long-chord vanes than in other cases. This results in unrivaled Tunnel Tech aerodynamic quality, as reflected in numerous reviews by professional skydivers and other customers.
All discussed above data, including the chord length and cooling options is available in Table 1 also.
Table 1. Comparative parameters for cases 1-5 of Figure 4.Case /
Vane type
ΔP (Pa) (*)
ξ (*) Chord length (mm)Cooling
1. No vanes, sharp turn
ΔP = 114 ξ = 0.47 –No cooling
2. Smoothly curved corner section
ΔP = 41 ξ = 0.17 > No cooling3. Simple radially-curved thin plates
ΔP = 80 ξ = 0.33 250 – 500 No cooling4. Closest competitors’ turning vanes, small chord
ΔP = 88 ξ = 0.37 280 YES 5. Tunnel Tech optimized turning vanes, large chord ΔP = 57 ξ = 0.24 500YES
(*) The values are valid only for the example shown @ 20 m/s, including 18m duct. For demonstration purposes.
The values of the hydraulic loss coefficient for the speed range up to 100m/s for the duct turn section with TunnelTech and competitors’ vanes, with no variation due to the choice of initial data, are given in Fig.5.
More details on hydraulic losses along the duct length, local resistance and total hydraulic loss coefficient are given hereunder.
Smooth and predictable pressure/velocity profile is especially important for applications where high turbulence or flow separation are not acceptable, such as experimental wind tunnels, indoor skydiving facilities, and high-power applications. These parasitic phenomena, as well as pressure pulsations caused by flow separation and large-scale turbulence, are also unacceptable in installations that require the absence of acoustically induced vibrations and where any static pressure deviations are not allowed due to air -duct structural stability requirements. Additionally, these turbulent flows are a common source of noise, further detracting from the system’s overall performance and comfort provided to the end-users.
It should also be considered that flow irregularities tend to further develop and intensify, if special straighteners, honeycombs, deturbulization nets or other airflow management devices are not used [1-3]. Precise gas dynamic analysis requires to calculate the resistance of each next airduct element taking into account the real inlet pressure/velocity profile, which is generated in the previous element of the hydraulic network. For long hydraulic networks it is often impossible to perform a CFD simulation of the entire system due to the huge dimensions. For such a situation, approximate semi-empirical calculations involving fluid dimensionless numbers and geometry criteria [4] or software based on such methods are used. Also, FEA modeling to determine duct structural stability is typically performed with a stable static pressure field applied to the duct walls. Thus, severe flow irregularities developing downstream can also introduce error into safety-critical investigations of load-bearing structures.
Approximate methods usually do not deal with the distortion of the velocity profile at the inlet to the hydraulic network element, and at best take into account whether the profile is developed or uniform, as well as the boundary layer parameters. In wind tunnels and industrial ventilation systems, each flow turn can cause such non-uniformity, creating a strong flow swirl, leading to uncertainty in hydraulic resistance calculations in such long hydraulic networks. Therefore, it is certainly important that care should be taken to avoid the formation of large velocity profile irregularities wherever possible.
It can be seen in Fig.6 and from the above demonstrated that the parameters of turning sections with TunnelTech turning vanes are such that they do not create additional flow disturbances but can also be used to dampen swirls and non-uniformity downstream of the turning section. Thus, the rotary section with TunnelTech vanes can also act as an effective flow straightener, is installed after the axial fan, duct diffuser, heat exchanger, test section, branching or tapping into a duct, or any other turbulence generating object.
Turning corner’s local resistance characteristics can be calculated using the well-known Darcy-Weisbach equation:
[math] \Delta P = \xi\cdot\rho\cdot\frac{v^2}{2} [/math]Where:
ΔP – total pressure losses (pressure drop) in Pa;
ξ – local resistance (Darcy-Weissbach) coefficient;
ρ – fluid density (kg/m3);
V – fluid velocity at the inlet cross-section (m/s).
These parameters, which determine the energy efficiency of the air duct, are highly dependent on the turning vane design.
According to [4] the total resistance of a complex hydraulic element can be represented as a sum of the length friction resistance ξL and local resistance ξ0:
[math] \xi_{SUM} = \xi_{L} + \xi_{0} [/math]For a rectilinear air duct the length resistance is proportion to the length and inversely proportional to the hydraulic diameter, which is expressed by the formula:
[math] \xi_{L} = \frac{L}{D} \cdot f [/math]
where f is the Darcy friction factor.
In case of simple shaped pipes (i.e. circle, square, hexagonal), f can be expressed by a nonlinear dependence only on the Reynolds number – see Chapter 2 in [4] or https://en.wikipedia.org/wiki/Darcy–Weisbach_equation
The friction factor f for a simple round pipe (circle duct) with smooth walls, with a developed stabilized flow profile at the inlet and for turbulent regime (Reynolds numbers Re > 4*103) can be calculated by the formula:
[math] {\displaystyle f = {\textstyle \frac{1}{(1.81 \, \cdot \, lg( \textit{Re} ) – 1.64)^2 } } }[/math]
For real ducts, roughness must also be taken into account.
Fig.7 below shows a plot of Darcy friction factor versus Reynolds number Re for various relative wall roughness, first published by Ninkuradze in [5-8]. This graph is also known as Moody’s diagram [9] or Colebrook-White correlation [10-11]. Modern study for smooth pipes can be found in [12].
This diagram shows the complex dependence of f(Re) for a round pipe having different roughness. For square and other non-circular pipes, the diagram will be more complicate. Thus, flow regimes (Reynolds number) the duct shape and relative wall roughness must be taken into account.
In the case of real rough ducts, it is still possible to represent the total resistance the as a sum ξSUM = ξL + ξ0 of the length resistance and the local resistance.
This representation of the sum simplifies the study of duct parameters, since the local resistance ξ0 can be calculated for a simplified element geometry – for example, in a periodic formulation of the problem with a smaller calculation domain or in a 2D version of the problem. Note the huge size of the computational domain of the examples shown in Fig.4, where the section has a height of 3 and a length of 18 meters, and grid convergence begins to appear adequately at a size of more than 10 million mesh elements. A variant of the problem formulation with periodic or 2D conditions for these cases could have an order of magnitude smaller number of mesh elements, and the simplified calculation of each velocity point for the ΔP(v) graph would take only take a matter of minutes or even seconds rather than hours.
Thus, partitioning into the sum of two resistances can significantly simplify calculations – one can quickly determine the local resistance ξ0 mad then the length resistance ξL can be added. The latter can be quickly estimated from known tables or by approximate formulas using simplified equations based on dimensionless numbers and airduct geometry parameters. For hydraulic and duct network elements with abrupt changes in the flow direction, (angled elbows, smooth bends, bends at different angles with and without turning vanes), a similar approach and method is presented in Chapters 6-1 and 6-2 in the comprehensive Handbook of hydraulic resistence [4].
Tunnel Tech’s air flow turning vanes (TTE-TV product) are at the forefront of this technology, offering unparalleled efficiency in airflow management. Our products are designed for a wide range of applications, from indoor skydiving facilities and wind tunnels to HVAC and ventilation systems, embodying the cutting-edge of aerodynamic design and energy efficiency.
Tunnel Tech’s high-performance airflow guiding vanes set the industry standard for power and aerodynamic efficiency. Our energy-saving turning vanes are engineered to minimize aerodynamic friction, ensuring smooth airflow and reducing energy consumption.
TunnelTech’s turning vanes have excellent air duct local resistance characteristics. Resistance parameters, calculated using the Darcy-Weisbach equation, as described above, are presented in the following figures (see Fig.8 below) and in the Turning Vane Datasheet.
In general, for the case where the duct size is unknown, values are given for an idealized element featuring periodic lateral boundary conditions, without taking into account the contribution made by additional wall resistance along the length, roughness and the influence of other local parameters. In the Fig.8 the values for an idealized rotary corner element with Tunnel Tech vanes are given, which was calculated in the infinite periodic sequence approximation of 15 blade stack with periodic boundary conditions.
If the HVAC or other hydraulic system consists of ducts that do not generally change the cross-sectional shape of the flow area along the flow path, it is convenient to estimate the resistivity per unit length for approximate calculations (to be estimated, of course, for the entire velocity range):
[math] K_{L} = {\displaystyle \frac{\xi_L}{L} } = {\displaystyle \frac{ \textbf{ f } }{D_h} }[/math] ,
where Dh is a duct hydraulic diameter.
The value of KL is easy to determine from reference books, as discussed above. Thus, by multiplying this by the length, and adding local resistance values ξ0 obtained from datasheets or calculated independently, it is possible to quickly estimate the total pressure loss in the system.
[math] \xi_{SUM} = K_L \cdot L + \xi_0 [/math] ,
The above illustrative examples shown in Fig.4 of a 2×2 meter square duct with the gas parameters and roughness used in the calculation has a resistivity per unit length of the order of KL = ξL / L ~ 2.1 Pa. This value applies when evaluating a square duct without accounting for bends, vanes, or other internal equipment. For a full length of 21 meters that the air mass travels along the duct will give a pressure drop of ~44 Pascals. Adding to this the value shown in Fig.8 (11 Pa for a velocity of 20 m/s taken according to the Turning Vane Datasheet (Table A.2.1) gives a total resistance of 55 Pa for a real 2×2 square duct section with rotary vanes in it. This value is in good agreement with the value shown in Fig. 4, case 5.
More information on approximate ways to calculate duct resistances of any shape without using CFD methods can be easily found [4] or similar literature.
NB! Please note that the examples shown in Fig.4 are only a special case to demonstrate the operation of the rotary vanes and cannot be used to evaluate an arbitrary duct! Figure 8 is applicable in a broader context, however, the specific parameters of the client’s duct need to be considered. Each specific system needs a detailed analysis, which you can order from Tunnel Tech. For an accurate calculation of the duct hydraulic resistance and an expert assessment of the energy consumption of your ventilation or wind tunnel equipment, please contact us.
Additional information about services and RnD can also be found in the Services.
Unique among guiding vanes for industrial air ducts, our products offer the capability to circulate coolant at a high flow rate, allowing for efficient cooling or heating of the air as it passes through the duct. This feature opens up new possibilities in thermal regulation for the use of indoor climate control vanes and low-resistance air-duct-integrated heat exchangers, providing our clients with versatile solutions for their airflow needs.
Evaluated using the HTCL (Heat Transfer Coefficient per Linear meter) calculation method, which quantifies the heat flux (in Watts) per meter of turning vane length for each Kelvin of logarithmic mean temperature difference (ΔTLMTD) between the external air and the corner vane coolant, our guiding vanes are engineered for effective heat dissipation across various airflow conditions, guaranteeing stable performance and temperature regulation.
Heat Transfer Coefficient parameters for the water-cooled turning vanes are presented in the Fig.9, both for wet and for dry air, where ΔP [kPa] represents the water pressure difference between inlet and outlet vane ports (blue and red in Fig.10).
Cooled turning vanes with integrated heat exchange channels offer a versatile solution for waste heat recovery across a variety of applications. When integrated into heat exchange systems, these vanes can capture excess thermal energy that would otherwise be lost, transferring it to heat recuperation systems, thereby significantly enhancing overall system efficiency.
In practical applications, this technology can be utilized in multiple areas. For instance, in industrial processes, cooled turning vanes can recover waste heat from exhaust gases and redirect it to preheat incoming fluids or air, thereby reducing energy consumption. In HVAC systems, similar principles are employed through devices like heat recovery ventilators (HRVs) and energy recovery ventilators (ERVs), which transfer heat between exhaust and incoming air streams. This process minimizes the energy required to heat or cool incoming air, leading to substantial energy savings.
Additionally, cooled turning vanes can be integrated into systems used in power generation and renewable energy sectors. For example, in combined heat and power (CHP) systems, waste heat from electricity generation is recovered and used for heating purposes, improving the overall efficiency of the system. In geothermal energy systems, these vanes can help manage the thermal energy extracted from the earth, optimizing the heat transfer processes.
In green and renewable energy initiatives, waste heat recovery plays a critical role in reducing carbon footprints and enhancing the sustainability of energy systems. This approach aligns with lean manufacturing principles by improving resource efficiency and reducing operational costs through effective heat management. Furthermore, in ESG projects, incorporating such technologies demonstrates a commitment to minimizing environmental impact and optimizing resource use, aligning with broader sustainability goals.
Tunnel Tech has extensive experience in implementing projects involving heat exchange and HVAC systems designed for waste heat recovery using cooled turning vanes. By integrating these vanes into heat exchange setups, engineered to capture and repurpose thermal energy that would otherwise be lost, Tunnel Tech enables more effective recovery of waste heat from various industrial and commercial processes. This approach not only improves energy efficiency but also supports sustainability goals by reducing energy consumption and operational costs.
Additional information on the design and optimization of rotary blades for wind tunnels, industrial ductworks, HVAC ducts and airflow management equipment, fan straighteners et.c. can be found at the links below:
See also:
For more information, please visit Beiouli.
Tunnel Tech’s aerodynamically optimized turning vanes offer unparalleled versatility and efficiency, suitable for a wide array of applications where airflow management is crucial. Our customizable air guide vanes are designed to integrate seamlessly into various systems, reducing energy consumption, minimizing noise, and optimizing aerodynamic performance. Below, we explore the diverse applications of our turning vanes, highlighting their benefits across different industries and scenarios.
Each of these applications benefits significantly from the advanced design and functionality of TunnelTech’s turning vanes, marking a leap forward in efficient airflow management. By choosing TunnelTech’s low-drag air guiding vanes, clients can expect not only to meet but exceed their system performance goals, all while
* – experimental results for the TT45Pro wind tunnel geometry.
For inquiries and more details on how our turning vanes can be tailored to fit specific needs, please reach out to our team. Let TunnelTech be your partner in achieving optimal airflow management solutions.
TunnelTech is committed to ensuring that the integration of our precision airflow vanes into your systems is as seamless and efficient as possible. Our dedication to excellence extends beyond design and manufacturing, offering comprehensive support for the installation and maintenance of our products.
The cornerstone of a successful installation is our detailed datasheet, which offers an exhaustive guide on integrating our turning vanes into various structures. This datasheet is meticulously crafted to include all necessary dimensions, load capacities, mounting options, and step-by-step installation procedures, ensuring a perfect fit and optimal performance in any system.
Key Features of the Installation Guide Dimensions and Specifications Precise measurements and specifications for each model of industrial ventilation vanes, accommodating different duct sizes and configurations Mounting Options Various mounting solutions to suit the structural requirements of your facility, including clamp-on, bolt-on, and weld-on options for diverse construction materials Load Handling Guidelines on handling aerodynamic loads, ensuring the structural integrity of the ductwork and the turning vanes under different operational conditions Step-by-Step Installation Clear, easy-to-follow instructions for installing turning vanes, designed to streamline the process and minimize downtimeTo maintain the unparalleled efficiency and longevity of our turning vanes, we provide a set of maintenance recommendations designed to ensure their continued optimal performance. Regular maintenance is crucial in preventing potential issues and extending the life of the product.
Maintenance Tips Include Inspection Schedule A suggested timetable for inspections, focusing on wear and tear, potential obstructions, and signs of corrosion or damage Cleaning Procedures Guidelines for cleaning turning vanes, including recommended cleaning agents and techniques to preserve their aerodynamic properties and surface integrity Wear and Tear Monitoring Advice on monitoring critical wear points, ensuring early detection and resolution of any issues Troubleshooting Guide A comprehensive troubleshooting guide to quickly address common concerns and prevent operational disruptionsTunnelTech offers ongoing support to all our clients, ensuring access to our team of experts for consultation on installation, maintenance, or troubleshooting. Our commitment to your success is reflected in our readiness to provide tailored support and technical assistance whenever needed.
By following our detailed datasheet and maintenance recommendations, clients can rest assured that their turning vanes will operate at peak efficiency, providing significant energy savings and improved system performance for years to come. For further information or to request a copy of our installation and maintenance datasheet, please contact TunnelTech’s customer service team.
Choosing TunnelTech’s turbulence reduction vanes means selecting a solution that offers significant energy savings, performance enhancement, and the versatility to apply to a variety of systems. Our turning vanes are a testament to our commitment to innovation, efficiency, and sustainability in airflow management.
You can find the specification table containing the key technical characteristics of the turning vanes and corner air duct assemblies here:
A friend of mine has recently given me some slightly used 20mm PVC ducting pipe.
Theres 60m of 20mm white cable duct in 6m lengths and 24m of 20mm green cable duct.
Now if I were using pvc pipe to make weapons I’d normally use PVC pressure pipe, which is the best suited to weapons as the coloured stuff is either too flexible or too brittle (although I have seen it used for weapons).
I am not sure how the white duct is the same grade as the pressure pipe but I am guessing it will be close enough to be weapon grade. Its not the best for swords (unless you can flatten it - you heat it up and squish it, though even then it makes heavy swords) but does suit hafted weapons quite well (maces, hammers, staves, spears, javelins).
From experience 20mm is ok for weapons up to about 1.5m long like staves and spears or 1.0m for maces and axes.
It is also useful for making props as well.
It is currently sitting at my friends place, I will probably cut it into 2m and 4m lengths for transporting it.
Let me know if you would like some, I’ll see if I can find a way of sending it to you, maybe I can courier some up to somewhere central in Auckland. Otherwise it’ll be in Hamilton until I come up to Auckland next.
Hmmm… I’m driving up the North Island to Auckland early next week. In a van. With a roof rack.
If anyone wants some bringing up, I could probably detour into Hamilton and get it. Similarly, if anyone in Wellington wants some, I can bring it back as well…
2m will fit in the back. 4 meters could fit on the top. 2m is easier.
I just have to know ahead of time so I can have the right stuff to tie it on with.
Also, I would want to drop it off at one place. Don’t really want to schlep around Auckland dropping bits and pieces off…
Maybe you could take a stack to say the nzlarps gear stash… and take some back to Wellington with you.
I’d be keen for a couple of 2m lengths for making weapons. I have an idea in mind for a staff.
Ditto.
Is foam pipe-lagging a good enough cover?
Please note that PVC pipe can get very brittle over time. We have stopped using it for the NZLARPs weapons in the auckland gear library. Although it is still good for handles, gun barrels etc.
Ditto.
Is foam pipe-lagging a good enough cover?[/quote]
Yeah, foam pipe lagging + PVC pipe + duct tape = boffer weapon. The issue I would like to point out here is that 20mm PVC is quite flexible at 2m, it will whip around.
I guess you could do a latex version finish over the foam lagging but I don’t know how you’d do the tips. The lagging would also need to be glued in place.
You could also wrap in foam and make a foam latex staff. I’d suggest 2 densities, the softer going on the outside. but it’ll end up quite chunky.
You can also use a carved pool noodle + latex for a staff too but it ends up quite chunky. nzlarps has one like this in the gear shed.
Either way you do it, its the tip ends which requires the most attention.
It can get brittle and a lot of that comes down to the grade of PVC used. I have been given old nzlarps weapons that had been made from PVC and they were crap because they were made from coloured PVC. The white PVC is the most durable.
I have a staff made from 25mm pressure pipe, its 10 years old and appears to be fine. Its the lagging which is a problem, its so old its starting to harden.
The real issue with PVC is its outer diameter is more like 23mm. Therefore any weapons you make using PVC end up quite fat by the time you have padded them. They also tend to be heavy. And maybe tends towards weapons that aren’t quite as pretty as fibreglass or carbon fibre cored weapons.
Sure. But its also (in this case) free. Which means we can get some quick & dirty stuff going while people learn to make the pretty.
OTOH, if any other Wellingtonians want to club together for a bulk order of that 2m x 12mm fibreglass rod from RD1, then I’d be in for that, and go straight to trying to make the pretty myself. You can 3-layer sandwich that with campmat, and its an instant staff or haft.
Sure. But its also (in this case) free. Which means we can get some quick & dirty stuff going while people learn to make the pretty.
OTOH, if any other Wellingtonians want to club together for a bulk order of that 2m x 12mm fibreglass rod from RD1, then I’d be in for that, and go straight to trying to make the pretty myself. You can 3-layer sandwich that with campmat, and its an instant staff or haft.[/quote]
Also Keen for the smaller stuff Idiot, I was thinking the pvc stuff would be great for props rather than weapons… but like you said, it could be good for practice
I would say that the PVC is OK for basic boffer type stuff, but even better for making frameworks to hang things on.
Because you can get standard pipe fittings from hardware stores, you can use them to create frameworks for LARPs and so on.
To hang cloth on.
To hang lights on.
They actually should be pretty flexible…
You can also heat the end of a pvc pipe and flatten it (by squashing it). The flat end is a perfect surface on which to glue two layers of closed-cell foam, so you can make axes, spears, javelins etc. The handles can be round, but the blades can be flat. As long as you resist the temptation to use pvc for a polearm, you should be fine
That’s good thinking, that quantity would be good for set dressing. You could make whole rooms or large tents out of that PVC piping, some corners, and some fabric.
Just as a note, my criticism of PVC for weapons is more about the limitations it has. I have seen fairly acceptable gear made from PVC and with a little care nice gear CAN be made. If its about putting cheap weapons in hand then it will certainly do the job.
And then theres the use for props and framing…
Let’s say hypothetically you wanted to use some of this for setting up tent-like buildings.
If it was in 2-meter lengths, you could make a structure that was 4m x 4m (height of 2m) using 16 of those lengths (32 meters of it). That would require 4 T-junction joiners and 4 corner joiners, 32 square meters of fabric for walls (we already have some grey fabric painted to look like stone wall), 16 square meters of fabric for ceiling, and some cord and pegs to attach fabric to frame and help it stay upright. It might want an extra four lengths to support the ceiling, which would also require some extra joiners.
Not really that big an expense. If you had a big 3m high center pole, you could make it look like a big pavilion. Or it could look like an old stone building. It would be quite modular, so you could make a couple of 2mx2m structures from it instead. Or a long narrow structure, 2m x 6m. By creating internal fabric walls, you could use it to make a multi-room building or a small maze.
This sounds quite feasible, and cheap given that the most expensive part would be the PVC and Jared has sourced it for free. I dunno what those corner joiners cost (AJ could help, he works/worked with PVC piping for a living), but I’m guessing we could spend less than $50 on joiners and then be able to create modular buildings immediately, using the fabric we already have and about with the option to expand it later with more fabric.
Hang on though… is 20mm diameter PVC actually thick enough to make free-standing structures? I may be thinking of thicker, heavier-weight PVC pipe, this might be too bendy.
I would also be concerned about the structural integrity.
I suspect that it might be necessary to put verticals at 1m-1.5m intervals, which would increase the PVC required by 18-24m.
For planar rigidity, rope can be strung across the diagonals and tightened to stop “panels” from deforming diagonally.
I believe it’s worth an experiment…
Something modular would be awesome.
We could add rigidity to the pipes by inserting a section of dowel that is about 1/3 of the length of the pipe. The dowel would be moved until it was in the centre of the pipe, then fixed into place with screws or nails. Now the middle section of the pipe, which is where it bends, will be very rigid.
20mm is maybe too bendy and too lightweight for a gazebo if its based on 2m lengths. Its probably ok to make something from if it wasn’t the only material used. The corner joiners etc would add a bit to its rigidity, so if you used additional pipe and constructed a PVC mesh (i.e. a 2m x 2m panel divided into 4 or 9 sections) then this would probably be strong enough.
The biggest challenge would be wind stress on the PVC. On a calm windless day a gazebo made from 2m x 2m panels would likely be fine. Inside, it would be fine. You could made a maze but you’d find you used up all the pipe very quickly.
Also if you are buying joiners then you really need to talk to a a plumber friend or at least someone with a trade account with one of the supply places. You don’t want to be paying retail price for this stuff… for instance the pipe is worth about $45 per 6m length.
I see what you mean. That approach would give the walls a lot more solidity. The walls should probably have a pipe running along the ground, too, with vertical joiners going up to support the vertical pipes.
It would also open up more options. Like 1m wide doorways with framework around them. Possibly windows. The walls could be transported and stored “made up” in 1x2m wall sections.
However, it would take masses of pipe. The 4m x 4m structure I suggested would require 80m of pipe for the walls if they were a 1x1m mesh. That’s almost all the pipe you’ve got, just for the walls, leaving us short for a ceiling. Although the walls wouldn’t be totally solid mesh (or there would be no way in), which leaves at least one meter spare. With 8 meters spare we could do the most basic 2x2m framework for a ceiling.
It would need a lot more joiners too (around 50), especially 4-way joiners which are probably more expensive. We might be able to fabricate our own joiners more cheaply using wider pipe and PVC glue, but the strength wouldn’t be as good.
For interior walls, I was thinking of just fabric strung from one exterior wall to another. I think we’d also want to paint all the pipe black or a dark woody brown, so it could be exposed in the interior but look okay.
In reality, if we want a small maze, we’d be better off buying a $130 gazebo (the long white ones) from the likes of Bunnings and using the PVC to extend it and add internals. By the time you look at fittings and joiners, you’d spend more than that easily if you scratch build one. The free pipe is only one aspect.
Also I have some 20mm flexible conduit as well (looks like vacuum hose), which is good for those sci-fi projects.
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