From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: BSFC change on staging
Date: Fri, 26 Jun 2020 17:37:06 +0800
References: <list-419682@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-419682@logan.com>
Message-Id: <5DC5568A-7E6E-4982-81E2-E4EC3B0175D1@gmail.com>

Hi Steve

I=E2=80=99m not sure my guess is as good as your given my inability to =
read a scale properly!!
So BSFC change and therefore fuel savings are negligible! A decimal =
place really does matter.

Cheers Steve


> On 26 Jun 2020, at 2:19 pm, Steven W. Boese SBoese@uwyo.edu =
<flyrotary@lancaironline.net> wrote:
>=20
> Steve,
>=20
> BSFC is calculated from the HP and the fuel flow.=20
> =20
> The HP is calculated from the torque and the RPM.  The engine is =
mounted  on ball bearings so it can rotate on the axis of the eccentric =
shaft.  That rotation is constrained with a 1 ft arm connected to a load =
cell calibrated in lb.  That gives torque in ft lb.  Torque in ft lb =
multiplied by RPM and divided by 5252 gives HP.
>=20
> Fuel flow is measured with a Floscan transducer calibrated in gal/hr. =
The gal/hr multiplied by 6.17 lb/US gal, gasoline gives lb/hr.
>=20
> Fuel flow in lb/hr divided by HP gives BSFC in lb/(HP hr).
>=20
> My EC2's are earlier version (SN 200-499) updated in early 2010 where =
Mode 7 allows setting the staging threshold.  The Renesis engine is =
fitted with a second CAS and a replacement trigger wheel with 12 teeth =
for the original CAS and one tooth for the added CAS. This allows =
interchangeability with my flying 1986 13B which has a stock CAS.
>=20
> Your estimate of fuel saving due to a BSFC change of 0.5 is correct.  =
Unfortunately, the observed BSFC change was about 0.05 rather than 0.5.
>=20
> Ed Anderson once told me that as a scientist, I collect data, but it =
takes an engineer to determine what the data means.  (He was smiling =
when he said that).  Your guess as to the reason for the BSFC change is =
as good or better than mine.
>=20
> Steve Boese   =20
>=20
> From: Rotary motors in aircraft <flyrotary@lancaironline.net> on =
behalf of Stephen Izett =
stephen.izett@gmail.com<flyrotary@lancaironline.net>
> Sent: Thursday, June 25, 2020 9:41 PM
> To: Rotary motors in aircraft <flyrotary@lancaironline.net>
> Subject: [FlyRotary] Re: BSFC change on staging
> =20
> =E2=97=86 This message was sent from a non-UWYO address. Please =
exercise caution when clicking links or opening attachments from =
external sources.
>=20
>=20
> Hi there Steve
> Thanks for your work here.
> How do you measure the BSFC?
> So you have a version of the EC software where you can still change =
the Staging point MAP.
> The BSFC is ~0.5 better unstaged. Is this due to better fuel-air =
mixing or is something else at play?
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> Am I right in thinking that at an economy cruise, a BSFC change of 0.5 =
might yield an approx 0.9G/hr ($5/hr) of fuel saving.
> That might then argue for a Staging Point at the earlier 15.5=E2=80=9D =
MAP to enable unstaged cruise rather than the locked in 20=E2=80=9D MAP =
of the current software version.
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> What is your thoughts and conclusion if you have reached any?
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> Thanks again Steve
>=20
> Steve Izett
>=20
> > On 26 Jun 2020, at 8:47 am, Steven W. Boese SBoese@uwyo.edu =
<flyrotary@lancaironline.net> wrote:
> >
> > I ran a test on my engine stand with staged and unstaged fuel =
injectors but with the same fuel flow and MAP.  The results are shown in =
the attached image.  The engine is a 2010 2nd generation Renesis 6 port =
from an automatic transmission car with the high RPM ports blocked off =
and stock fuel injectors.  The reduction drive ratio is 3.18:1.  The =
prop is a 3 blade 72" Warp Drive and was operating just below stalled =
RPM.  A turbo is installed but no boost was used in the test.  No =
attempt was made to operate at minimum BSFC.
> >
> > Steve Boese
> > <BSFC.jpg>--
> > Homepage:  http://www.flyrotary.com/
> > Archive and UnSub:   =
http://mail.lancaironline.net:81/lists/flyrotary/List.html
>=20
>=20
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   =
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