View Full Version : CALLING ALL BOFFINS !!!

Andrew Wiggin - n/a
18-Nov-08, 12:12 PM
Me and my dad are getting a new vemon hull. We are planning to put the old running gear from are Alien 503. My dad was just wandering want would the tip speed of the fan blades in a 900mm duct.

nickyd - n/a
18-Nov-08, 02:06 PM

Are you asking what it will be or what it should be?

If you are asking it what it 'will' be with your original running gear then you, or we, would need to know what speed you want to turn your engine at and the reduction ratio you are running. i.e. the sizes of your top and bottom pulleys. It is then simple maths to work out how fast your blades are turning. A bit more maths then you have your tip speed.

If you want to know what the tip speed 'should' be then if I told you that you might beat me! The construction regs have maximum tip speeds in them. Would be worth checking them out.


Paul Fitz - n/a
18-Nov-08, 05:44 PM
If you check the downloads page, you will find that Andy C. (Webby to his friends) has put on, the new version (v1.3) of the Belt calculator.

It now includes a section which calculates tip speeds and gives a recommended pulley centre-distance to help reduce noise levels.

Input your existing pulley sizes and engine speed and it will spit out the answer without recourse to pencil and paper http://hovercraft.org.uk/images/icons/smiley_icons/icon_surprised.gif)