Many PVC boat owners face the limitations of regular tanning motors, and the propeller works only when there is sufficient depth, and in grassy shallow waters or wetlands, it is often useless. jet-plantAble to turn an ordinary inflatable boat into a high-speed all-terrain vehicle, not afraid of grass, nor silt, nor shallow water.
Redesigning a boat to an air propeller is not just an engine replacement, it is a complex engineering task that requires accurate calculations and an understanding of aerodynamics. Unlike traditional engines, thrust is created by throwing away mass of air, which radically changes the behavior of a vessel on the water. Aerolodge It is capable of developing high speeds even where a conventional motor would have long ago stalled or wound a bundle of algae on the shaft.
However, before you start to take up tools, you need to realize that installing a powerful propeller imposes serious requirements on the design of the boat. Incorrect calculation of the center of gravity or insufficient rigidity of the transom can lead to unpleasant and sometimes dangerous situations on the water. In this article, we will discuss in detail all the stages of creating and installing your own aeroplant to ensure that your project is successful and safe.
The principle of operation and advantages of the propeller
The main difference between an aeroplant and a classic outboard motor is that there is no submerged part. propellerIt's an air-based system that works regardless of the state of the surface under the bottom, and it's a unique way to move around overgrown bodies of water, where the blades of a conventional propeller would instantly fail.
The key element of the system is the engine, which, through the gearbox or directly transmits rotation to the propeller, most often used for this purpose, car engines or specialized motors from snowmobiles, which have high torque at low revs. Efficiency of the propeller lower than that of the propeller, so a significantly higher power of the power plant is required to achieve a comparable speed.
Among the main advantages of such modernization, users highlight:
- 🚀 Passage: the ability to move on grass, silt, shallow water and even ice without the risk of damaging the screw.
- 🛠️ Simplicity of construction: lack of lower unit, reducer in water and complex cooling system with off-shore water.
- 🔇 Environmental friendliness: No emissions directly into the water and a lower risk of pollution of the reservoir of fuel.
⚠️ Attention: Airships are highly sailable and sensitive to lateral winds, and high-speed steering requires a great deal of habituation and a great response from the steering wheel.
Selection of power plant and calculation of thrust
The heart of your future aeroboat will be the engine, and its performance will directly affect the dynamics of acceleration and maximum speed. PVC Or small-class aluminum boats, engines ranging from 600 to 1,300 cubic centimeters are often the best choice. More powerful units can create excess traction that will be dangerous for light inflatable construction.
When calculating the required power, the total weight of the outfit should be taken into account, including the weight of passengers and cargo. There is a rule of thumb: for comfortable planing, approximately 1 horsepower is required for every 10 kg of weight, but for aeroplanes this factor may be higher due to the aerodynamic resistance of the frame and propeller. Designed traction must provide access to planing in an acceptable time, usually not more than 10-15 seconds.
When choosing an engine, pay attention to the following parameters:
- ⚙️ Type of cooling: Air cooling is preferred because of its simplicity, but requires careful temperature control.
- 🔄 Rotational direction: It is important to align with the direction of rotation of the screw, especially if a standard gearbox is used.
- 📉 Weight: too heavy motor will shift the center of gravity and may require alteration of the entire aft part.
For a standard two- or three-seater PVC boat, an engine with a capacity of 30-50 hp is quite enough. Excessive power will require strengthening the structure and can lead to the destruction of cylinders from the air jet created.
When choosing an engine (preferably) model with an electric starter, as manual start of a powerful motor on water can be difficult.
Design of frame and engine attachment
The frame of the aeroplant is a load-bearing element that experiences tremendous vibrational and dynamic loads. It must be not only strong, but also light, so as not to overload the craft. Most often, duraluminum profiles or stainless steel pipes are used for manufacturing. Strength of construction - the main priority, since any backlashes will lead to rapid destruction of nodes and discomfort during operation.
The engine attachment must be secure and accessible for maintenance. Usually the motor is mounted on vibration insulators that quench the high-frequency vibrations transmitted to the boat hull. It is important to allow for the ability to adjust the angle of the engine to adjust the thrust vector. The wrong angle can (lead) to the fact that the boat will either burrow nose or, conversely, sloat.
The main requirements for the frame design:
- 📐 Geometry: The frame should not block the flow of air to the screw and interfere with the vision of the steering.
- 🔩 Fastening: use only high-strength bolts and nuts with grovers or fixing composition.
- 🛡️ Defense: The presence of a protective casing around the screw is necessary for the safety of people on board.
⚠️ Attention: When welding aluminum structures, use argon to avoid disturbing the metal structure. Steel frames require careful corrosion-resistant treatment.
Selection and balancing of the propeller
The propeller is a tool that converts engine torque into thrust. For boat aeroplant, screws with two or three blades are most often used. The fabrication material can range from wood and composite to aviation aluminum. Rotor diameter selected based on the engine power: the more powerful the engine, the larger the diameter, but within reasonable limits of the dimensions of the boat.
A critically important step is static and dynamic balancingAn unbalanced screw will create a very strong vibration that can break the bearings of the engine in minutes and destroy the frame mounts, balancing by removing metal from the heaviest blade or adding load to the light one until the beats are minimized.
The specifications of the propeller affect the behavior of the boat:
- 🌪️ Screw pitch: It's the ratio of speed to thrust. The big step is for speed, the small step is for thrust.
- 🌀 The shape of the blades: It affects the efficiency of work in different modes of rotation.
- 🛑 Braking: Some screws allow the use of reverse, but on aeroboats more often used rotary rudders.
How to check the balance of the screw at home?
Static balancing can be done with two parallel knives or sharp edges that are placed horizontally, and the screw is placed on them with an axis, and if it spontaneously turns a heavy blade down, weight adjustment is required, and a perfectly balanced screw must remain in any position.
Control and steering system
Unlike conventional boats, where the rotation is carried out by the relaying of the engine or the rummel, the aeroboat is controlled by means of air rudders located behind the propeller. The air flow from the propeller flows around these rudders, changing the vector of the vessel's movement. The efficiency of steering depends directly on the flow rate, so at low speeds maneuverability can be reduced.
The control mechanism must be reliable and moisture-proof, and the control cables are laid along the side and connected to the gas sector and steering levers. duplicate control or a "Dead Man's Switch" system that shuts down the engine if the steering wheel falls overboard.
Control system components:
- 🎛️ Steering column: It can be of a motor vehicle or motorcycle type.
- 🔗 Cable wiring: It requires regular lubrication and checks for grinding.
- 🚦 Instrument panel: The tachometer and temperature sensor are required to monitor the operation of the engine.
☑️ Audit of the control system
Comparison of installation specifications
When planning an upgrade, it is useful to compare different configurations. Below is a table showing the dependency of the specifications on the type of engine and propeller used, which will help determine the choice of components for your particular case.
| Parameter | Motorcycle engine (IZH/Ural) | Automotive engine (Oka/VAZ) | Specialized Rotax |
|---|---|---|---|
| Power (hp) | 28 - 35 | 35 - 55 | 50 - 65 |
| Installation weight (kg) | 40 - 50 | 60 - 80 | 45 - 60 |
| Fuel consumption (l/hour) | 8 - 12 | 10 - 15 | 12 - 18 |
| Cost of reworking | Low. | Medium | High. |
As you can see from the table, motorcycles are winning in weight and cost, but they're losing power. Car engines provide a great supply of traction, but they make the stern heavy. The optimal solution for boats up to 4 meters long is often two-cylinder car engines with a volume of about 750 cubic meters.
Safety regulations and tests
The first watering in a homemade aeroplant is a critical moment. The tests should be carried out in calm weather, away from bathing areas and shipping lanes. You must have life jackets on all those on board. Before starting the engine, make sure that there are no people or foreign objects in the rotor zone.
During the break-in, carefully monitor engine temperature and body vibrations, and any extraneous sounds should be a signal for immediate stop and diagnosis. Security above all, so do not neglect protective casings, even for the sake of aesthetics or weight loss.
The first 5-10 hours of operation are considered break-in, during which it is not recommended to load the engine to more than 70% of the maximum power.
Regular maintenance will prolong the life of your installation, check the tightening of the bolts after each release, as vibration is the main enemy of all connections, lubricate the moving parts of the steering and monitor the condition of the cables.
Do I need to register an aeroplant in GIMS?
Yes, any modification of the craft that changes its design features or engine type requires changes in the documents. An aircraft with a capacity of more than 5 hp is subject to mandatory registration, permission to convert and undergo inspection.
Can I use the air propulsion unit in the winter?
Yes, aeroboats are great snowmobiles, but you have to keep in mind that there is lower resistance to snow and the boat can reach a higher speed, you also have to take care of protecting the engine from snow entering the cooling system (if it is airborne) and use frost-resistant materials.
Which screw is better: wooden or aluminum?
Wooden screws are cheaper and easier to manufacture, they absorb vibrations better, but they are afraid of moisture and impact. Aluminum is stronger, easier and more stable in operation, but require more accurate balancing and more expensive in production. For constant loads, aluminum is preferable.
Installation of air propulsion setup on a boat is a complex but exciting process, opening new horizons for water tourism. The right approach to design, quality materials and safety measures will allow you to create a reliable and fast vessel that will become a source of pride.