In the interest of accuracy, this is not really correct Paul.
It was 13 years from the start of building my Long-EZ until first flight
- which was with a ducted fan. But I did not work on the ducted fan for
13 years.

I worked on the airframe from 1986 to 1997. I bought the rotary engine
January 1997, had it installed and was doing taxi testing with the first
ducted fan by Summer 1998. First flight was July 1999 on the second
ducted fan.

So actual ground experiments with ducted fans only consumed about 1 year
before first flight. I experimented with a third ducted fan after it was
flying.

I flew it for 500 hours with the ducted fan, until December 2004. Top
cruise speed achieved was 135 knots, engine speed 5400 RPM. With the
same engine (the engine has not been removed from the plane since 2001)
with RD1B and 62/68 3-blade prop top cruise speed is now 160 knots,
engine speed 6400 RPM. I am getting more power out of the engine now
since I can turn it up higher. Flying at 5400 RPM now, I am back around
130 knots again.

Some of the drag of the duct can be offset if the duct has a dual use as
a horizontal/vertical stabilizer. See my LSA proposal at
http://www.bridgingworlds.com/LSA.htm

Perry
http://www.ductedfan.com

Even tho the speed is the same at 5400 RPM the power generated
is less. One needs to know the intake manifold pressure at a
given RPM to determine the HP consumed.

What is the intake manifold pressure now at 5400 RPM Perry?

> Paul Lamar


At 3500 feet manifold pressure is about 28", including may 1/2" for ram
pressure.
To get to 5400 RPM I had to throttle back to about 22" manifold pressure.

Perry

So what you are saying I guess is it take about 22% (22/28) less HP
sans the duct to cruise at the same 135 kt speed all other things
being equal. What is the old fan pitch and diameter?


Paul Lamar ...No rotor no motor.

The fan was 37.5 inches in diameter and had a pitch of 38 inches.
Because of the duct shape the airspeed through the fan was higher than
the aircraft cruise speed.
38" pitch at 5400 RPM works out to 194 mph or 168 knots.

It was definitely much noisier than the prop I'm flying now. With the
fan I was pushing 900 fps
at the blade tips while the prop I'm flying now is only around 750 fps.

Perry


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