Ducted fan for propulsion

[Mike O'Connell]

Anyone know of a source for an electrical ducted fan in the range of 30-40 pounds of thrust ?

If not electrial, how about ?

[messabout]

Mike;
Intrigueing question.... Makes me wonder why you'd want such a propulsion device.

Del Rio is hard by the Rio Grande and I am told that is very shallow in places. Thats a good enough reson for wanting an air driven boat. I think you have a sizable reservoir just north of del Rio (Amistad). Plenty of water there no doubt.

It will require much more power to develope 30 to 40 pounds of thrust in air than it would with a Min-Kota or similar underwater trolling motor. Therefore you'll need more batteries. The Ducted fan will be noisy enough to negate the advantage of electric motors.

A few of the Florida airboat guys have tried ducted fans but they are big and use a substantial Lycoming, or Continental aircraft engines. There are quite a few air boaters who have big block V8 Chevrolet or Ford engines. Talk about noise, those things are deafening. It is mostly prop noise that we hear because the engines are, by law, muffled. The point is that a lot of power is needed to get anyplace with an air prop on a boat.

I have seen, in the distant past, a clamp on air drive for row boats. They had a cage around a fan of about 24 inch diameter. The fan was driven by a Briggs or similar motor. They worked but did not produce much speed and indeed they were noisy. The term fan above is used to identify the type of blades that were used. It looked pretty much like a shop floor fan complete with wire cage. If you want to build from scratch, consider one of the ubiquitous 25 to 30 cc engines as used on weed trimmers. A new Homelite brand is about $99. A far superior brand is Zenoah or alternatively a Fuji. Those little things will produce in the region of 5 HP. They're priced in the $300 range. These are common in good hobby shops. They have recoil starters and clutches. Matter of fact aircraft model hobbyists may provide some good information about the ducted fan system. Try Googling ducted fan.

Tell us more about your idea

Gene

[kach22i]

What would that be in CFM?

Conversion:
http://www.madsci.org/posts/archives/2000-11/975597528.Ph.r.html

I'm thinking you could use a large leaf blower.................maybe not.

link:
http://www.amazon.com/Husqvarna-Backpack-Blower-473-2-Model/dp/B0008FXOZ0
Technical Details

* Engine: 44cc 3 HP
* Air Velocity MPH: 177
* Air Volume CFM: 473.2
* Additional Features: Lower noise and emissions, Tube-Mounted throttle control, Padded harness and load reducing hip pad
* Weight: 23 lbs.


http://ec2.images-amazon.com/images/P/B0008FXOZ0.01-A1787XOD7Q2I4M._SS500_SCLZZZZZZZ_V39359846_.jpg

It's lots of work building your own duct and getting the tolerances just right.

I've looked into HVAC fans, some set up with electric motors. These are heavy and don't generat lots of thrust because when used in buildings they need to be quiet and not blow people around. Super duty fans used to bring fresh air down into mines are heavy and not designed to be mobile at all.

I've been looking for a pre-made fan and duct set-up which could absorb a typical automobile engine's power, lets say 200-300 hp. I've had no luck. Smitty airplane/hairplane company looked like they were going to bring something on to the market for ducted jet-like kit planes, but they have not followed through. I think they were just fishing for investors at Oshkosh a few years ago.

You will find that hovercraft use ducted fans the most. Lots of information here:
http://www.hoverclubofamerica.org/forum/

[Pericles]

Have a look at a Ring thruster at http://www.fleetwatermarine.com/Fleetwater_propulsion.htm

It should work for you.

Pericles

[kach22i]

Have a look at a Ring thruster at http://www.fleetwatermarine.com/Fleetwater_propulsion.htm

It should work for you.

Pericles

That's cool.

Just ignore everything I wrote if the thrust pounds are intended to be used and measured in water instead of air, I'm confused.