Hovercraft

[falconmaster]

Originally Posted by adamrp

Im one of the hovercraft builders (along with edomus) and maybe you can help us predict what exactly is going to happen when we throw this thing together... Basically, we are using a bag skirt. We have an 11HP engine that is direct-drive to a 6-blade fan with a diameter of 24" (a little bigger, really). This is a very home made craft, so it is all built on top of an 8'x4'x3/4" plywood sheet. Do you think it will hover the way it is supposed to? I think the hover height will be about 8 inches.

arp

11hp is good for about one person. Take the total weigt and divide by surface area. That will give you the static pressure you need to acheive exualibrium. let say you are 100lbs, and you have 1m square that makes 100lbs per square meter , or .1lbs per square cm of pressure you need to be able to generate to achieve "zero weight". If you can somehow build an enclose to test the static pressure of your powerplant then you can predict how much weight you can lift.
Hover hieght is dependent on your skirt height and the statci pressure you can maintain. It is an illusion though. Even though you look like you are barely leaving the ground the skirt is flexible and can flex to clear obstacles. The is the lift cushion hieght that is critical, because that is what will get hung up when you try to clear obstacles.

I had a 650 cc snowmobile engine in the hovercraft I built and I could lift 600lbs with a 6 inch hoverheight and I could travel at about 15 to 20 mph. I had one three blade prop that provided both lift and thrust. About one third of the air volume was used for lift, and two thirds for thrust. I will dig up some pics and send them to you!! Hope that helps.