How to Decide Dimensions of an RC Airplane – Part 3

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RC Airplane Series – Part 3

In this article, we are going to discuss designing the plane, and after which, in the next article (RC Airplane Series – 4), we will discuss how exactly we should select a motor for our RC Airplane. There is a proper procedure for motor selection, which is one of the important steps in RC airplane designing. 

Table Of Contents
  1. Designing the plane
  2. How to Apply the Theory?
  3. Conclusion

Designing the plane

This RC Airplane Series is going to be for ‘Beginners’ or for those who are not very experienced in this field, but just want to know the basics of RC Airplane. For this reason, we avoid getting into the details of the analysis. The actual Analysis includes a lot more, like: Airfoil selection through XFLR software, ‘Ansys Fluent’ software for model analysis, etc. 

But for now, we keep it very simple

For beginners, a suggestion would be to use online available plans in order to develop your aircraft. By readymade plans, I mean that you can get information with figures about the dimensions of the fuselage, rudder, elevator, horizontal stabilizer, vertical stabilizer, and all.

Text version for the above flowchart
  1. Select a plan from online resources
  2. Select the material which you are going to use for your plane (e.g., Depron, Balsa, Styrofoam sheets, etc.)
  3. Calculate the approximate ‘mass’ of the components by using the relation: ρ=m/V\rho = m/V, where ρ\rho is the density of material
  4. Calculate the total mass of the plane by adding up the masses of all the components. This will be your ‘model weight’ (say) since it is the weight of only the plane (excluding electronic components)

How to Apply the Theory?

Let’s take an example for now: 

I have considered this below shown plan as an example. You will get a lot of such similar plans online on various youtube channels and website. 

The one that I am using below is from this video: Video Link. I have modified the plan a bit for simplicity! And also, this website has a lot more plans. Do check it out.

Design-Plan-example-final

  • As shown in the above flowchart, after selecting a plan, we need to choose the material which we are going to use.

In this case, I decided to go with Styrofoam, and after which I searched for the density of Styrofoam on the internet, or you can also get it in the ‘specifications’ section from the website page, using which you are going to buy it.

The density came out to be 60 g/L.

  • Then, We calculate the mass of the seperate component using the density formula.
  • For this, first calculate the Area first. Area can be calculated by breaking the figure into simple geometric figures (rectangles, triangles, trapezium, etc.). Then, calculate volume, and then calculate mass using the density formula.

Volume=Area×thickness of the sheetVolume = Area \times thickness\ of \ the \ sheet

ρ=mV\rho = \frac{m}{V}

Conclusion

This was a very short article on the design of RC airplanes. We will for sure discuss this topic again at an Advanced Level. But for now, for the Beginners stage, let’s keep it simple and easy to understand. After all, that’s our main goal.

Enjoy Learning!

RC Airplane Series

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