Mark, what model MT prop/diameter and controller did you install and do
 you
remember the cost or did it produce selective amnesia?

Also, some folks report their MT electric control system has a
 significant
lag period between input and pitch change, especially in pattern, etc,
although the last time I flew one with a rotary engine I don't remember
 it
being that bad.  You?


Steve Beckham

 Steve,

 It has been years since I ordered my M/T prop.  I would have to dig out
 the
 paperwork to find the model no.  It was a 76" as is recommended by
 Lancair.
 I bought it through Jim Ayers who was doing a group buy, so I got a
pretty
 good price (relatively speaking).

 I normally fly it with a combination of pitch and throttle, unless on
long
 x-country flights.  Then I normally fly WOT at 1700 prop rpm.  This gives
 me
 around 5200 rpm on the engine and 158-160 TAS with a fuel burn of 11.3
 gph.
 If I need to go faster, I change to 1900 prop rpm.  If I really want to
go
 fast (190 TAS), and burn lots of fuel (20+ gph), I go to 2100-2200 prop
 rpm
 with WOT.  I don't fly like this very often, but its nice to have
options.

 You're correct in that the electric controller is slow (slower than a
 hydraulic), but you get used to it.  The method I've developed for
landing
 is this... a few miles out from the airport I adjust the prop to 1900,
 wait
 for the engine to speed up and settle in to the new rpm, then switch the
 prop controller from AUTO to MANUAL and then fly it like a fixed pitch
 from
 there all the way to touchdown, adjusting speed with the throttle.  At
 this
 setting the 20b has plenty of power to do a go-around if needed.

 My takeoff setting is 2200 prop rpm.  With slippage, I'll see 7200 rpm
 initially and then after a few hundred feet of ground roll it will bite
 and
 rpm will drop down to about 6800.  (Because of this, I bring the power in
 slowly, unlike a Cessna 152/172). This airplane really accelerates and
 requires a bunch of right rudder to keep it on the centerline.  When
clear
 of the 50ft. obstacle, I start dialing the prop back slowly until I
 finally
 reach my cruise setting of 1700/5200 rpm.  Last flight I saw 1600-1700
fpm
 climb rate.  Not too bad for a 2100 lb. 4-place airplane running an auto
 conversion.  I hope to see 2000 fpm climb rate once I get my new p-port
 engine done.  ;-0

 Mark S.



--------------------------------------------------------------------------------

Very good information Mark.  Once we got the power up on even the two
rotor
engine years ago we found that some sort of adjustable pitch propeller was
essential for realizing the full efficiencies and potential of the engine.
You could fly and fly well with a fixed pitch prop but there were very
large
compromises. The deal-breaker for most folks with the MT and other prop
options at this point appear to be primarily cost.  And prop tip velocity
and efficiency is limited to some degree by the inherently thicker tip.

Steve Beckham

I remember the time to climb contest at Sun & Fun and you guys changed the
prop for the
time to climb contest :)

As I recall your rotary powered RV airplane running NOS with Allan Tolle
flying set the
all time un official record from a dead stop to 3000 feet in less than one
minute. Of
course most of your competitors were using NOS as well. I keep forgetting.
Was that an
RV4 or RV3?

Paul Lamar

--------------------------------------------------------------------------------


Paul, it was the prototype Mazda conversion (iron housing) engine we first
sorted in the RV-4. For Sun'n Fun that year we removed the SuperLight
prototype in Alan's RV-3, took the conversion engine out of the RV-4 and
built a quickie mount to put it in Alan's RV-3 because the RV-3 smaller and
lighter for time-to-climb as well as a click faster for a given h.p. at top
speed due to smaller size.  Had to retard timing for nitrous and add extra
set of fuel nozzles just outside the port in runner.

Steve Beckham