Message-ID: <40747FF3.8010703@netdoor.com>
Date: Wed, 07 Apr 2004 17:25:55 -0500
From: Charlie & Tupper England <cengland@netdoor.com>
Reply-To: cengland@netdoor.com
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: : Percent Power, Throttle position, & RD-1Cperformance
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oops! I knew better than to forget that. The intent of the question was=20
to get numbers that can be compared to cruise  fuel burn to a Lyc 160 at =

~75% power. Implied is 7k to 9k feet. 9.5gph * 6lb per gal / .45lb per=20
hp hr =3D 126.6 which is ~ 75% of 160 hp. I could cruise at 7-9k feet &  =

190 - 195 mph at about that fuel burn.

Charlie


Tracy Crook wrote:

> Altitude!  Altitude!  Must know altitude.=20
> =20
> I can go 190 mph at SL or at 15,000.  Fuel burn is about double at=20
> SL compared to 15K.
> =20
> Tracy
> =20
>
>     ----- Original Message -----
>     From: Charlie & Tupper England
>     Sent: Tuesday, April 06, 2004 9:03 PM
>     To: Rotary motors in aircraft
>     Subject: [FlyRotary] Re: : Percent Power, Throttle position, &
>     RD-1Cperformance
>     =20
>     OK, how about a 'real world' cruise power fuel burn? My 160hp fixed=

>     pitch Lyc powered -4 burned ~92-9.5 gph of avgas at ~190-195 statut=
e
>     mph. What are you burning down around 190 mph (allowing a little
>     wiggle
>     room for 'work in progress' aerodynamics of your plane)?
>
>     Tracy Crook wrote:
>
>     > Took closer note of throttle position on todays flight. At 2000
>     ft the
>     > throttle was only about 1/3 open (position of throttle quadrant,
>     but
>     > it closely mirrors butterfly position) at economy cruise setting
>     which
>     > was 6.0 GPH. This is about 42% power, 82 HP according to the EM2
>     which
>     > is fairly close but not perfectly calibrated yet. The same power
>     > setting with the -B drive would bave been a bit further open.
>     > I did a quick check of MAP at 1000 ft at full throttle and found
>     I was
>     > not getting any drop at 150 MPH and had .5" boost at 220 MPH
>     (ram air
>     > recovery I assume). I did not get around to checking it in slow
>     climb
>     > which would more accurately compare to what you would see on a dy=
no.
>     > Finally got some reasonably calm air to do performance
>     comparisons of
>     > -C drive vs -B drive. Without the prop blade cuffs it looks like
>     the
>     > break even point is at 203 MPH. Above that -C burned more fuel th=
an
>     > the -B. After installation of the cuffs, the break even point
>     was off
>     > the scale! i.e., above top speed with -B drive. I had a good data=

>     > point on the -B drive while burning 17 GPH (209 mph during SUN 10=
0
>     > race). At the same speed, the C drive was burning 15.8 gph. This
>     was
>     > better than I had hoped for.
>     > Tracy
>     >
>     >     Thanks, Tracy. I was hoping there would be someone out there
>     >     flying with the same TB diameters.
>     >
>     >     Like most things, TB diameter is a tradeoff. My conclusion fr=
om
>     >     the dyno data is that 44mm per rotor (1 =C2=BE) is a bit smal=
l as the
>     >     MAP is dropping off over 5000 RPM. But if you want to idle at=

>     >     1500, and have a decent transition from there to 3000; 1 =C2=BE=
 is
>     >     good. For a 2.85 to redrive, I=E2=80=99d want to increase tha=
t flow area
>     >     by 30% or so =E2=80=93 to about 2=E2=80=9D dia for each rotor=
=2E
>     >
>     >     My data may not be representative because of restricted flow =
to
>     >     the TB. The =E2=80=98airbox=E2=80=99 size is restricted by th=
e cowl, and may
>     have
>     >     restricted the flow a bit. In hindsight, it would have been
>     smart
>     >     (and easy) to make a run with the airbox off and see what
>     >     difference it made.
>     >
>     >     Al
>     >
>
>
>
>     >>  Homepage:  http://www.flyrotary.com/
>     >>  Archive:   http://lancaironline.net/lists/flyrotary/List.html
>