flyrotary@lancaironline.net Mailing List Archive

Message

Hi Rusty, I arrived at the same conclusion regarding the propulsion of a gyro copter about 20 years ago. The results of my efforts were a single seat gyro with a KAWA 440 engine driving a ducted fan(not a shrouded propeller). First flight was in 1992. Performance was not overwhelming with 35hp and close to 400lb gross. But it proved the point. By 2000 I started upgrading to a ROTAX 583 (>90hp). At the same time I started with the AVID and the SOOB conversion, and got into the Rotary stuff at the same time.

I have not given up on this yet, and still have every thing here.

The pictures are from flight testing in 1995 at CEW.

I will be glad to share everything I learned if you are interested.

Richard Sohn
N-2071U

----- Original Message -----

From: Russell Duffy

To: Rotary motors in aircraft

Sent: Sunday, September 17, 2006 6:53 AM

Subject: [FlyRotary] ducted fan questions

Greetings,

I'm still thinking of using the single rotor engine for a gyrocopter, and started considering the possibility of using a ducted fan to eliminate a couple problems.

Problem one is the lack of a proven redrive for the single rotor, and problem two is height of most gyros. Since the rotor has to clear the pusher prop, the mast ends up being really tall, and the prop is usually shortened as much as possible.   This means you end up with an 8+ ft high gyro that won't fit in the garage, and a short 60" prop which is far less than ideal for thrust.

I know nothing about ducted fans, so I'm looking for a bit of a reality check. If I want to run direct drive blades at 7500 rpm, it looks like I need to keep them around 32" in diameter to stay around .9 mach. This seems really short, but short is great as long as it works.

Can anyone venture a guess as to how long the fan unit would have to be? Would it end up being as heavy as a redrive, or is there weight to be saved.

Thanks for any thoughts. It may just be a wild and crazy idea, but I had to ask.

Cheers,

Rusty (out of touch till evening)

Attachment: ucfly.jpg

(63K)

Attachment: webfan.jpg

(47K)