Model Dear friends, I am working on a model rc airboat and I'have several questions. The model is fiberglass construction, it measures 75 cm boat length, 40 cm beam and the all boat package will weigh 1.5 to 2 kg. I need know who explosion engine and the propeller would be indicated. I wrote this text in Spanish language too because I am not sure you undestand me in my poor english and I hope that spanish people in America can undestand me in spanish. Thanks in advance and greetings from Spain.

Apreciados amigos modelistas, estoy haciendo un modelo de airboat rc y tengo varias preguntas. El modelo es de fibra de vidrio, mide 75 cm eslora, 40 cm de manga y el conjunto final pesará 1‘5 o 2 kg. Quisiera saber que motor de explosión y que hélice serÃ*an los indicados. Pongo este texto también en español porque no estoy seguro de saber expresarme bien en inglés y espero que entre ustedes se halle algún hispano que me pueda entender. Gracias de antemano y saludos desde España.

Hi- Mine will be about 70cm by 45 cm, about the same weight, powered by an O.S. 40. So maybe for you, you can use from .35 to .46 engine? I am still learning, this is my first build, and I will build another later based upon the performance of this one. I have two propellers for this boat, a two-blade 10x6 (25.4mm x 15.24mm) and a 9x7 3-blade (22.8mm x 17.78mm). Your engine will dictate your propeller choices. Since I am new at this, don't make any choices until more members have responded, they will know better. Good luck! -Chris

For us that don't use the metric system....
3.3 to 4.4 pound boat.
29½ x 15¾"

If the boat were heavier, I'd say use a .61 engine...But a .40 - .46 should be plenty of power.

Thanks all for your answers. I think finaly to use one .40 engine. I have one question about the prop, I've seen yours model photos and there are some people with a two blades prop and another with trhee, if the three blades have diameter smaller than two, for equal performance, it's very suitable for to get an low gravity center boat, why the most models have two blades prop? I'm sorry for ignorance and my english. Best regards

I have not yet proven it, but some people believe that a 2-blade gives better high speed performance, while the 3-blade gives better thrust at the lower RPM's. This is why I have a 10x6 2-blade, AND a 9x7 3-blade. I will find out for myself when I finish my airboat. Obviously, the 3-blade will allow me to mount my motor 1/2" lower.
EDIT- And then there are those of us that are SUPPOSED to use Metric, and find it largely annoying... [:'(]

Thanks ToyStory, for your answers. I think that i'll use a 3 blades propeller if it gets me a low gravity center, it´s the best for correctly sail. I have another question about the deflectors or air rudders. I've seen a lot of solutions, more wide in upper part and more lower narrow, narrow upper part and more wide lower, high rectangle, low rectangle, long rectangle, short rectangle, one rudder, two rudders and many between these combinations. When is interesting to use any case? The surface rudder is function of what? Best regards. Salu2 para todos.

There are advantages to every type of setup. In the end I think it really is more about personal preference and what you want to get out of your boat.

I've used single rudder, dual rudder, v-tail dual rudders and water rudders (not at the same time) on various different setups. V-tails will torque a boat toward the outside in a turn. A frame style dual rudders will make a boat lean into the turns. I've heard that tall single rudders will make a boat lean into the corners but I haven't specifically experimented with this.

My personal preference is single rudders. I've had good luck with them and they are easy to set up.

hola spanish canjangator

como creo que ya te dicen por ahi,tu motor es un 40

puedes pasarte por nuestro foro español de miliamperios.com y en la seccion de barcos te asesoraremos en todo lo que podamos

saludos