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?
Hi Perry - Interesting read, your Ducted Fan/ vertical stabilizer/
rudder idea. One aspect that concerns me is that part of Burt's great
idea to put the rudders at the wing tips - they have quite a moment all
the way out there and yours I would think also generate quite the moment
arm in the duct, "while under power" - but what happens when you pull
the power back to your rudder's effectiveness just when you actually
need it ? That is on landing with or without engine power ?
-dave
It's not my idea, I think it was Raspet's. It's been done before in the
Marvel?
I think the reason the Rutan canards have swept main wings is so that
the winglets can be far enough aft to work as vertical stabilizers and
incorporate rudders.
And like the Rutan canards, there would be a rudder on each side of the
duct, and they would only deflect outward. Left pedal to left rudder and
right pedal to right rudder. Since the rudders only deflect outward,
they would mainly have an effect on airflow on the outside of the duct.
My LSA concept is based on the Solitaire, which is a canard sailplane
but it has a straight wing, no winglets. The vertical stabilizer and
rudder are conventional at the tail end of the fuselage. I replaced that
with the ducted propulsor to dual-use as vertical stabilizer and rudders.
The only time I use rudders on my canard is for steering on the runway
above 40 knots, and to kick the nose straight just before touchdown in a
crosswind landing. I always use the crab technique because the wing low
slip doesn't feel right and is harder to do in the Long-EZ than the
crab, and it would probably be easy to scrape a lower winglet on the
runway if it wasn't executed perfectly.
Perry
Perry just as a matter of interest please try a forward slip at high altitude and
tell us what happens. For example is the canard stable or
does it buck in yaw or pitch? I am curious. The C 172 with full
flaps pitch bucks a little bit in a forward slip.
Paul Lamar
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