View Full Version : fan advice please.

jon_curtis - n/a
4-Dec-08, 08:37 PM
28hp in 925 duct, engine 7000rpm reduction 1:2.42

intergrated craft, which is very light!

five bladed 5z?


jon_curtis - n/a
11-Dec-08, 04:42 PM
no one able to help me on this?

jar2 - n/a
11-Dec-08, 05:21 PM
Too fast Jon - tip speed works out at 140m/sec. It will be very noisy - recommended is 122m/s.

Ian Brooks has a calculator (see HERE (hovercraft.org.uk/downloads/files/block_0/estimating_thrust_lift-D.pdf)) that will work it all out properly.

Ian Brooks - n/a
14-Dec-08, 02:09 PM
Been a bit busy lately... whats it for? PM if its a big secret!


tonybroad - n/a
14-Dec-08, 04:10 PM
i've just tested a 28hp engine in a light integrated craft weighing just under 100kg with a 920 duct with 6 5Z blades in a 9 bladed hub - fan is spinning 3-3500 rpm which is getting towards maximum tip speed of 168m/s

it hovered OK with an adult in and skirt pressure seemed OK but is intended for a junior/cadet craft

lift will suffer a little more with a 5 in i reckon

i currently run 5 bladed fans in the same hull and duct with 50+Hp engines for our F3 craft and it's fine with those

movie of the 28Hp craft's first flight is on my website (under construction)

hope that helps


jon_curtis - n/a
15-Dec-08, 04:27 PM
hi tony

thanks for the advice, think the flying fish now use the 5 of 5 5z over the 6 in 9, from what i have heard, the lift is similar and they are slightly faster? anyone with a 5/5/5z shed any light?

Thanks all