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Modelhovercraft - n/a
30-Dec-07, 04:29 AM
where is the best place to buy fans from?



What sizes do they come in? from smallest to largest.



What size engines are required for certain sized fans?



How much should they cost?

Iceman - n/a
30-Dec-07, 03:36 PM
I'm afraid those questions are very vague. The chicken and egg question comes to mind!



You need to establish your airflow requirements first, then physical size/weight limitations, and these will give you an idea of the size of fan(s) you will need and the power requirements needed to drive it/them.



Different fans/fan setups are used depending on lift/thrust requirements which depends on weight and size of the hovercraft.



There are various publications which will help you to determine what setup you should be aiming for.

Vortex - n/a
30-Dec-07, 10:16 PM
Hi there,



I am the European and North American distributor for Hascon fans widely used on racing and crusing hovercraft. Give me a call 07793807073 or better still let me have some more details via e mail so I can do some figures for you.



sales at vortexservices dot net



Keith

Modelhovercraft - n/a
31-Dec-07, 02:57 AM
In regards to fans. so far we have been working on the lift fan only. trying various methods to see which produces the best air flow.

We Have tried massive electric motors with propellers which work well with big 20 inch propellers at various pitches but draws so much current from the battery. your average car battery lasts about 3 minutes at full power. as soon as you reduce the speed the speed controller blows up in a cloud of smoke. I think we are drawing a massive 200+ amps at full power. We have also found that to power the craft electrically you would need a forklift to lift the battery's so we think electric power is out of the window. Not to mention adding water spray to the equation.



We have looked into Model sized engines. The glow fuel type you see in model aircraft. Which unfortunately have the reliability of a Lada. (sorry Lada owners). You need up to a 50cc sized 2 stroke model engine to turn a 20 inch prop. But they sound so horrible and c**p. you know WEEEEEEEEEEEE! Bumblebee in a bottle. They Use weird expensive fuel mixes. are pigs to start and get set up. (i am not happy playing with a mixture screw on the carburetor 1 inch away from a 20inch prop spinning at 10,000rpm plus) I feel a fingerless visit to the hospital coming on. Not good.



So whats left. Jet engines and real engines. ie Briggs and striation.



Jet engines are almost ruled out due to the crazy expense of a turbo prop engine. We are talking of 4000+ and we need 2. They only produce the same power as a small 4 stroke engine.

They don't like water spray at all. I err blew my little model test gas turbine up using it to power a small model boat a few years ago. Not to mention the ridiculous noise you get from them. Not good testing the hovercraft in your back garden in a residential area.



We have tried a centrifugal blower unit which was custom built at 20 inches but needs to much power and HP to make it effective.



We have a brand new 3.5hp 4 stroke vertical shaft engine from a nice cheep Argos petrol mower. Lovely engine. starts first pull and chugs away quite happily. Fit a 20 inch prop and it sounds like a lawn mower but with rather alot more wind. So great results there but we want to get a 20 inch multi blade fan to compare to the propeller. I would assume it would be alot more quieter than a prop and probably safer. As a prop is alittle like a lawn mower blade. With the fan you can also adjust the pitch so you can set up to suit the engine in regards to revs and torque.





In regards to thrust, the craft is having 2 ducted fans but testing those with engines is a long long way off.

Don83000 - n/a
31-Dec-07, 04:26 AM
Some of the refrigerated lorries have quite a nice multi bladed fan of around 20" on the fridge pump and the one we had did have adjustable pitch blades and a fan is going to work better in a small dia lift application than a prop. Having said that you had been looking at using jet engines etc so cost can't be a concern therefore just buy a Hascon hub and blades job done.

A fan is going to be noisier than a prop if you want quieter then use a centrifugal fan.