Fan fun!


I have always thought there must be something better than the plastic air-conditioning fans we use to lift and propell our racing machines.  One aeronautical engineering degree later, and I am just about getting a decent enough understanding to think about doing it!

Its also taken a long time digging up decent information on ducted fans for propulsion (let alone getting it into my head), so i plan to share what im doing. So if you’re a fan design guru reading this and can see a better way please put me back on the right track! My main sources are shown below.

Before we try to start a new design from a clean sheet, we need to have a better idea of our requirements (MORE THRUST isn’t really helpfull…).

What are the requirements for a racing hovercraft thrustfan?

Next we need to find the baseline using the blade which most people are using- the Hascon/Multiwing 5Z blade. Whats wrong with it and how could it be improved?

The baseline design: Multiwing 5Z fan

Now its time to design a new blade in aerodynamics land, and find out if the possible improvements are big enough to go to the effort of actually making it, bearing in mind how you will actually make it, and if it can be made strong enough.

-Prototype fan design aero

Finally its time to think of the best way to make the shape of the blade and connect it to as many horsepowers as possible without it bananaing uncontrollably.

Structural design

Making the moulds

Also to race it you need to test it!

My original threshold to get to the last few steps was 10% improvement in thrust for the same engine power and fan diameter, however on paper 6% is looking more likely. Im gonna do it anyway, because I love to make things and I see this as an essential step in my goal to becoming the F1 world hovercraft champion!
Not to mention the hours and $$$ I have invested to date (£27k student loan…)

Sources:

R.A. Wallis: Practical fan design

Ducted fan design book by F. Marc de Piolenc & George E. Wright Jr.

Ducted fan design code by Marc Drela and Hal Y. as well as the ES2 version by Philip Carter

Theory of wing sections by Abbott and Doenhoff

Javafoil and Javaprop by Martin Hepperle

Multwing Optimiser fan selection program

-Many NACA and NASA papers

Thanks for help from:

Rupert Baker, Tom Brufato, Alister Simpson, Marc Piolenc, Bob Parks, Philip Carter, Keith Oakley and many others i have pinched ideas from

Posted in: Fan design, General on March 31st by admin


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