Carter Wind Solutions, Ltd. — 300 kW Tilt-Down Wind Turbines

Anatomy of the Machine

The Components

The Carter 300 kW turbine is a lightweight, flexible system with a filament-wound spar that bends and twists to shed excess wind energy — two blades, a slender guyed tower, a compact downwind nacelle, and the winch that makes crane-free service possible.

A galvanised storage rack holding several grey composite Carter rotor blades with their aerofoil cross-section visible, outside the factory

Composite Blades

Two Flexible Blades

The Blade

A teetering two-blade rotor built on the NASA LS-1 profile. The blades are deliberately flexible — they shed gust loads by bending rather than fighting them, cutting fatigue through the drivetrain and tower and allowing a far lighter machine.

2-Blade Teetering Rotor
NASA LS-1 Profile
Flexible / Load-Shedding
Downwind

Close-up of the teeter bearing assembly at the rotor hub that supports the two blades, with wiring and a junction box visible — Teeter bearing supporting the blades.

The blade hub is mounted on teeter bearings, which allow controlled movement of the rotor assembly. These bearings help absorb blade and hub vibrations, reducing the transmission of bending and torsional loads to the main drive shaft, gearbox, and tower structure. By accommodating dynamic rotor motions, the teeter system improves component life and enhances overall turbine reliability.

One of the most significant dynamic loading events occurs during sudden shutdowns, grid loss, emergency stops, or other operational interruptions. During these events, the tower can deflect into a pronounced “S-shape” as it absorbs and dissipates the rotor’s kinetic energy. This behaviour is a normal part of the turbine’s design and can appear quite dramatic to those unfamiliar with flexible wind turbine structures.

Counter Balance Arms

Two Flexible Blades

Blade Counter Balance Arms

Cast counter-balance arms and root fittings that carry each blade at the teetering hub. Balancing the two-blade rotor keeps loads even through the drivetrain and tower, and the arms are produced as matched sets ready for assembly.

Cast Alloy Arms
Matched Sets
Teetering-Hub Mount

A Carter two-blade turbine head on its guyed tower against a blue sky, showing the counterbalance arms below the rotor — Overspeed Safety — Counterbalance arms — passive overspeed protection.

The counterbalance weights serve as an independent overspeed safety device. If the rotor speed increases beyond its design limit, the centrifugal forces acting on the weights at the ends of the arms increase proportionally. These forces generate a torsional moment on the blade assembly, causing the blades to automatically change pitch toward a stall position. As the blades stall into the feathered position, aerodynamic force is reduced, limiting rotor speed and slowing the turbine. Once the rotor speed has decreased to a safe level, the mechanical brake mounted on the drive shaft can be applied to bring the turbine to a controlled stop.

Close-up of the Carter turbine nacelle and counterbalance arm — Counterbalance arm detail.

Chart of aerodynamic torque versus rotor speed for one blade pitched at 30 m/s, with linear-fit equations for four pitch cases — One blade pitched — aero torque vs rotor speed (30 m/s).

Chart of rotor speed versus time after grid loss at 30 m/s, comparing one-blade pitch-up with normal pitch-up, with derived empirical equations — Grid-loss response — rotor speed vs time (30 m/s).

Plot of vertical force on the rotor in a non-rotating coordinate system over time (0 to 300), ranging roughly -10 to -40 thousand N, with the approximate extracted equation Fv(t) about -25 + 3.5 sin(0.15t) + 1.8 sin(1.8t) kN — Vertical Force on Teeter Pin — Fv(t) ≈ −25 + 3.5 sin(0.15t) + 1.8 sin(1.8t) kN
**Typical fatigue and dynamic loading spectrum on blade and support assembly.**

Plot of axial force on the teeter pin over time, with the approximate extracted equation Fa(t) about 28 sin(2.2t) + 4 sin(0.1t) kN — Axial Force on Teeter Pin — Fa(t) ≈ 28 sin(2.2t) + 4 sin(0.1t) kN
**Typical fatigue and dynamic loading spectrum on blade and support assembly.**

Aerial view of a full Carter rotor blade laid out on a workshop floor, instrumented with a row of loading actuators and weights along its length for a full-scale bending test — Full-scale blade bending test.

A blade root section under a load rig on the workshop floor, set up to bend the filament-wound spar at its attachment to the root fitting — Filament-wound spar attachment to root fitting bending test — location of maximum bending stress.

Finite-element von Mises stress analysis of the CWT filament-wound GFRP I-section spar under combined bending and torsion: 234 MPa peak at the fixed end, 142 MPa mid-span, 38 MPa at the tip, with material properties, section properties, the stress equation and a factor of safety of 2.35 — CWT spar — von Mises stress (GFRP I-section). Peak 234 MPa at the fixed end; factor of safety 2.35 against the fibre-direction allowable.

Detail of a blade root: the white composite shell cut away to reveal the filament-wound spar seated against its metal root fitting — Spar root detail.

Schematic

Spar curing oven.

From the Blade Shop

Period photographs from Carter blade production — spar protection and final finishing.

Blade spars over the treatment tank in the Carter factory — each welded steel spar is hot-dip protected end-to-end before the aerofoil shell goes on. Finished spars queue on the racks behind.

Blade root and pitch hardware being finished in the paint shop — the blade sits in a rotating fixture so the surfacer and topcoat go on evenly around the full section.

Galvanized tapered tubular tower sections laid out at the Carter Wind Turbines factory yard in the UK

Slender Guyed Mast

The Tower

A slim steel tower held upright by guy cables rather than a heavy free-standing tube. It carries the rotor with a fraction of the steel and sits on a much smaller foundation — lowering cost, weight, and ground disturbance.

The tower is fabricated from rolled steel plate welded into tapered tubular sections that are assembled on-site. During installation, adjacent tower sections are joined by drawing them together with a hydraulic ram, creating a strong and reliable connection.

It is intentionally designed with controlled flexibility to absorb the kinetic energy generated during rapid turbine shutdowns. By flexing and twisting under load, the structure reduces peak stresses and helps protect both the turbine and tower components from shock loading.

The tower base is mounted on a hinged foundation connection, allowing the structure to accommodate bending loads without transferring excessive moments into the foundation — improving structural efficiency and reducing foundation requirements.

All tower sections are sized to fit within a standard 40-foot shipping container, minimizing transportation costs and simplifying logistics for domestic and international deployment.

Welded Tapered Sections
Hydraulic-Ram Joints
Controlled Flexibility
Hinged Base
Ships in 40′ Container

Close-up of the main tower support at the hinged base, showing the pintle, bearing and bolted steel fittings that carry the tower — Main tower support.

Close-up of a guy cable ground attachment: the cable swaged to a threaded turnbuckle and shackle bolted to the ground anchor — Guy cable ground attachment anchor.

Close-up of the gin-pole attachment at the tower pivot, showing the hinge plates, pin and bolted steel fittings at the base — Gin-pole attachment to tower pivot.

Close-up of the tower base end fitting on the ground, showing the cast pivot bracket, bolt holes and spanners during assembly — Gin-pole attachment to tower pivot.

A Carter Wind Turbines crane-truck lifting a galvanised tower section into position at the Orton wind farm site, with more tower sections and a mobile crane laid out across the field behind — Orton wind farm taking shape — once installed, no tall cranes are required. During the India construction we used a local farm tractor with a front-end loader to lift the nacelle and assist building the site.

A Carter turbine being raised on its guyed tilt-down tower using a gin-pole and ground winch, with workers in hard hats watching as the tower lifts toward vertical — Tower-turbine raising at Orton using a gin-pole — the nacelle assembly is as heavy as a truck.

A Carter Wind Turbines crane-truck with the nacelle and rotor lowered to ground level in a field

Comparison diagram of four wind-turbine tower types — guyed tilt-up, guyed lattice, freestanding lattice and freestanding monopole — shown in elevation and plan view with guy radius and tower base footprints — Guyed vs Freestanding Towers — Footprint & Foundation Comparison

Tower section end fitting with the coupling tongue used to draw adjacent sections together with a hydraulic ram — Section Coupling

Galvanized tapered tower sections in the factory yard, jacking holes visible along the section — Tapered Tower Sections

Galvanized hinged tower base fittings and ground anchor sets laid out on the apron at the Carter Wind Turbines factory — Hinged Bases & Ground Anchors

Steve standing in front of a row of Carter two-blade turbines on guyed tilt-down towers, with a tower rest stand visible behind — Steve inspecting the turbines. Over his right shoulder is the Tower Rest Stand used to support the tower assembly when down.

At our Orton Wind Farm Cumbria in the UK — note the tower rest stand.

Labelled engineering cutaway drawing of the Carter nacelle assembly identifying the Blade Hub (P-100), Tower Joint (P-200), Generator (P-300), Gearbox (P-400) and Drive Shaft (P-500)

Assembly Drawing

Power Conversion

The Generator

The generator converts the rotor’s mechanical power into electricity, sized to the machine’s 300 kW rating. Mounted in the downwind nacelle alongside the drivetrain, it is kept compact and serviceable so the whole power head can be brought to ground level for maintenance.

Direct coupling to the gearbox output keeps the assembly simple and reliable, and the unit is matched to the turbine controller for grid-synchronised output, instantaneous power measurement, and real-time fault and alarm monitoring.

300 kW Rated
Grid-Synchronised
Gearbox-Coupled
Nacelle-Mounted

Power curve comparison chart: the CWT Model 300 reaches about 290 kW versus a typical turbine plateauing at 250 kW, plotted against wind speed from 4 to 24 m/s — Power curve comparison — CWT Model 300 vs a typical turbine.

Interactive Estimator

Annual Energy & Income

Enter your site’s mean wind speed and electricity price. The estimate applies the CWT Model 300 power curve across a Rayleigh wind-speed distribution (the IEC standard derived from the mean) to predict yearly output and revenue for one turbine.

Mean wind speed (m/s)

7.0

Energy price (per kWh)

Capacity factor

—

Annual energy

—

Annual income

—

Estimate for a single CWT Model 300 turbine using a Rayleigh wind distribution and a typical 95% availability. Actual output depends on site turbulence, air density, wake losses, and grid availability. Indicative only — not a performance guarantee.

Interactive

Power & Energy Estimator

Adjust the inputs to see the wind-energy equations recalculate live. Defaults are example values for a Carter-class 300 kW machine — enter your own site figures to model your installation.

Design Inputs

Example values — adjust to your site

Rotor Diameter 28 m

Wind Speed 12 m/s

Power Coefficient C_p 0.46

Air Density ρ 1.225 kg/m³

Capacity Factor 30%

Captured Power

— kW

Swept Area

— m²

Power in Wind

— kW

Betz Maximum

— kW

% of Betz Limit

—%

Est. Annual Energy

— MWh

Power Curve — Output vs Wind Speed

Illustrative model using standard wind-energy physics. Captured power is capped at the 300 kW rated output above rated wind speed, as a real turbine would limit via pitch/stall control.

Generator Build — Workshop

Period photographs from generator and drivetrain assembly.

Fitting the generator rotor to the main shaft in the workshop — the finned rotor slides onto the shaft taper, sling-supported until the fit is drawn up. The same shaft carries the rotor hub at its far end.

The complete drivetrain trial-assembled on the shop floor: generator frame in the nacelle cradle, output coupling and slip-ring stack toward the yaw plate — checked as one unit before the shells close around it.

Three Carter nacelle assemblies on pallets outside the Carter Wind Turbines factory, with the workshop and overhead crane behind

Carter Wind Turbines · UK

Downwind Powerhead

The Nacelle

The compact nacelle houses the generator and drivetrain and sits downwind of the tower, so the rotor naturally tracks the wind with minimal yaw machinery. Kept light and simple, it is the part that comes to ground level for service.

Built and tested at our own workshop, each nacelle assembly is delivered ready to lift straight onto the tower pintle — here, a batch of completed units stands palletised outside the factory ahead of dispatch.

300 kW Rated
Downwind Yaw
Compact Drivetrain
Low Mass

Engineering sectional drawing of the Carter gearbox and main shaft assembly, showing bearings, shaft seals and the 65 rpm input rated for 78-foot diameter blades — Gearbox Assembly — Blade Attached Directly

Carter nacelle covers and rotor components packed inside a shipping container bound for New Zealand

In Transit

Shipping & Logistics

Nacelle Covers On Shipment

The lightweight composite nacelle covers nest together for efficient transport. Here a set is packed into a standard shipping container ahead of export — part of a consignment bound for New Zealand.

Nested Composite Covers
Container-Packed
Export Ready

Great Orton, Cumbria Movable Carter winch and its reinforced concrete winch pad in a field, cables running up to the guyed tower

The Winch · Crane-Free Service

Winch and Winch Pad

A ground-level winch lowers and raises the entire hinged tower under controlled tension — no crane and no tower climbing, which makes the Carter machine ideal for remote sites and dramatically cheaper to install and maintain.

The turbine is equipped with a winch and a reinforced concrete winch pad. The winch is movable, allowing a single winch to be shared among multiple turbines within a small wind farm.

This approach reduces installation and maintenance costs while providing flexibility for turbine erection, lowering, inspection, and servicing operations. The winch pad provides a stable, durable foundation for safe operation under all weather conditions.

Controlled Tilt-Down
No Crane Needed
Ground-Level Service
Single-Visit Maintenance

The Orton mobile winch on its pad with the gin-pole attached, rigged and ready to lower the tilt-down tower — Orton mobile winch. Gin-pole attached lowering the winch to its ground bolts getting ready to tilt the tower over.

The Controller · TMC3

A Purpose-Built Turbine Controller

The controller monitors the live operation of the turbine and all associated assemblies and reports operational data remotely to the operations center via a cellular link. Operations personnel can monitor and control each turbine day to day and measure power output instantaneously, with alarms, faults, and warnings detected and communicated in real time.

Recognizing the need for improved safety, reliability, and operational efficiency, Steve entered into a joint venture with Orbital Sciences of Denmark to develop a new turbine controller.

The controller was designed in-house and jointly developed with Jens and the engineering team at Orbital Sciences. Following development and testing, the controller was manufactured by Orbital for deployment across the Carter Wind Turbines fleet.

The new system incorporated the latest electronic interfaces, enhanced sensor technology, and improved communications capabilities. These advancements provided greater operational awareness, increased reliability, more accurate performance monitoring, and enhanced safety throughout turbine operation.

Live Remote Monitoring
Cellular Link
Instant Power Readout
Real-Time Alarms & Faults

Annex B wind farm system diagram: a 300 kW induction generator turbine with a 0.415/11kV 500kVA transformer feeding 11kV switchgear, groups of turbines 2-5, 6-10, 11-15 and 16-20, an 11/0.415kV control building auxiliary supply, and an 11/33kV transformer to the PES 33kV system through a metering circuit breaker and point of isolation — Annex B — Wind Farm System Diagram (point of connection and common coupling to the PES 33kV network)

Single-line electrical schematic of the Orton wind farm: ten 300 kW two-blade turbines (WT1 to WT10) grouped to three substations at 11kV and 415V, with G59 protection, incoming supply, turbine HV isolation and HV import/export metering to the NORWEB grid — The wind farm grid connection was isolated to 3 separate switchgear.

Interior of a Carter turbine control cabinet showing the Active Control boards, I/O interface, relay logic board, terminal blocks and field wiring — Inside the control cabinet — Active Control boards, I/O interface, relay logic and field wiring.

TMC3 Wind Turbine Controller overview: an all-in-one control, supervision, communication and data-logging system for 10 kW to 1 MW turbines — TMC3 — All-in-One Concept

TMC3 interface diagram showing digital, counter, PT100 and analog inputs and outputs, CAN, Ethernet, RS232, RS485, USB and SD-card interfaces, grid surveillance and generator control — Interfaces & Connections

TMC3 specifications: 24 digital inputs, 6 hi-speed counter inputs, 8 PT100 inputs, grid surveillance with ROCOF support, relay and analogue outputs, PM alternator control, and USB, RS232, RS485, CAN, Ethernet and SD-card interfaces — Capabilities & I/O

TMC3 interface legend listing digital, counter, PT100 and analog inputs, digital and analog outputs, and CAN, Ethernet, RS232, RS485, USB and SD-card interfaces with icons — Interface Legend