From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: Dyno Sheet
Date: Sat, 8 Aug 2020 06:48:22 +0800
References: <list-614607@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-614607@logan.com>
Message-Id: <532B2263-DBAA-43AC-AD73-035FB1414C4A@gmail.com>

Hi Charlie and all

On the four runs - Speeds were:=20
147 KIAS 21.6=E2=80=9D @ 9500 WOT
136 KIAS 18.2=E2=80=9D @ 7500 (Not WOT)
160 KIAS 24.8=E2=80=9D @ 6000 WOT
165 KIAS 26.2=E2=80=9D @ 4500 WOT

Prop hub is Airmaster 3 blade electric with Aerotek Blades=20

On looking over the 4500 ft run:
	As RPM steps up from 5500-7250 (in 250rpm inc) over 9 mins (OAT =
49)
	Temps gradually build from 172/154 to 198/171 (Oil/Water)
	Fuel Flow goes from 14.5 peaking at 16.2 (6750) before ending at =
15.8
	KIAS 160 peaking at 168 (7000) before ending at 166

We probably haven=E2=80=99t allowed enough time between changes for full =
settling of the numbers, but the trends seem consistent.

Not sure I agree with your thoughts re engine rpm rising and drag =
constant or rising =3D power must be increasing.
Torque x RPM =3D Power=20
RPM is increasing, but if torque is decreasing faster than rpm is =
rising, power will be decreasing.

What I was interested in discovering was the max power RPM.
My logic is, even if power is constant after 6750rpm (ie. rpm increasing =
matches torque decreasing) there is no value in spinning her above that =
rpm.

What science could I do to discover this?
Rightly or wrongly, thats why I value this list, I was looking for the =
peek in Fuel Flow AND IAS (I=E2=80=99m relying on the wideband O2 being =
accurate and keeping mixture constant)
Its not anything like dramatic, but I think I can maybe see evidence of =
that best power (torque peek) RPM being somewhere around the 6750rpm =
setting.
We had been spinning her up 600+RPM higher, perhaps for no advantage.

On another note about the Intake manifold. We shortened the OEM unit to =
lift peak torque from Mazda's 5000rpm documented curve, hoping for =
something in the low 6000=E2=80=99s.
We also kept the VDI valve that opens at high RPM to provide Mazda=E2=80=99=
s Renesis intake shockwave charging, but presently I cant activate the =
valve in flight.
And to be honest it seems to be producing a pleasing amount of hp at =
that 6750rpm.

On Takeoff with a mixture at a Lambda of 0.9 / 13.2 AFR she is burning =
17 Gal of our Premium Unleaded fuel using 1 Ounce / Gal of two stroke =
oil, whatever hp that equates too.

Is my logic OK here or am I just dreaming?

Cheers

Steve


=09

=09


> On 7 Aug 2020, at 10:34 pm, Charlie England ceengland7@gmail.com =
<flyrotary@lancaironline.net> wrote:
>=20
> That's curious. Are you saying that fuel flow *decreased* as rpm =
*increased* above 6750 rpm? And airspeed decreased, as well? The only =
way fuel flow should decrease as rpm increases is if the load on the =
engine is going down.
>=20
> Is the prop running out of pitch (or ability to absorb the HP) as you =
get faster? Is the airframe hitting a drag wall due to cooling drag =
(still shouldn't show a reduction in fuel flow; it just wouldn't go any =
faster)?
>=20
> What actual speeds are you achieving when this is happening?
>=20
> Refresh my memory; who's prop (what blades) is it?=20
>=20
> Do engine temps go up as you get above 6750 rpm?
>=20
> Think about the 'airplane as dyno' thing: If rpm continues to go up, =
and the drag (our substitute for torque on the engine brake in a real =
dyno) stays the same or increases, then power *must* be increasing, and =
so must fuel flow. Simple math; (torque*rpm)/5252. So, was the plane =
going downhill, or was the prop unable to absorb the additional power =
and decoupling, unloading the engine?
>=20
> Charlie
>=20
> On Fri, Aug 7, 2020 at 9:01 AM Stephen Izett stephen.izett@gmail.com =
<flyrotary@lancaironline.net> wrote:
> Hi Guys.
>=20
> Today we did some engine data analysis at 9500, 7500, 6000 and 4500 =
feet agl.
> WOT with constant best power mixture of 0.9 Lambda.
> We looked at Fuel Flow and IAS at 5500,5750,6000,6250,6500,6750 & =
7000rpm.
> The data revealed a very slight peak in both IAS and Fuel Flow at the =
6750rpm point at basically all altitudes.
> I think what this is suggesting is that increasing rpm beyond 6750 is =
only increasing wear and has no benefit given the current intake/exhaust =
configuration.
>=20
> With the current Prop Fine Pitch Limit, on initial WOT at Takeoff the =
engine consistently hits 6900rpm within ~6 seconds and 7000rpm by =
liftoff at 70 KIAS.
> It then generally builds to 7400rpm (With no pitch adjustment - We =
presently don't have a Constant Speed Controller) before throttling back =
as we turn downwind.
>=20
> I think this would suggest we ought adjust the props fine limit =
marginally so that takeoff WOT yields approx 6700rpm and keeping the rpm =
as close to 6750rpm as=20
> possible when seeking maximum power by manual prop pitch adjustment.
> A Constant Speed Controller would be nice!
>=20
> I=E2=80=99m now thinking we have enough data to tune the Mixture =
Correction Table of the EC2=E2=80=99s computers for climbing at 6750rpm =
and as Bill suggested cruising at 6000rpm.
>=20
> Next step in tuning in the Glasair Super IIRG will be playing with the =
cowl flaps and cooling drag. Presently the flaps are wide open and =
draggy.
> I=E2=80=99m in the process of completing a little box of 5 =
differential pressure transducers (MPX10DP=E2=80=99s) mounted under the =
cowl.
> I worked out that they interface quite nicely without any other =
circuitry with the Dynon Skyview's surplus EGT inputs via a new =
Polynomial in the sensor config settings.
> So hoping in the next few weeks to ascertain how the inlets, diffusers =
and outlets are functioning or not.
> What I like about the MPX10 interface with the Skyview EFIS is the =
simplicity of displaying the pressure data inflight while its all logged =
along with engine and flight data=20
> for analysis on the ground.
>=20
> I=E2=80=99ve got 7 more hours of Phase #1 testing.
> So far both aircraft and engine are really great.
>=20
> My friend and test pilot Dawie also demonstrated at the end of todays =
flight - a Lazy Eight, a Roll and Wingover.=20
> I felt sick for the next 3 hours. I don't think aerobatics will be in =
my future.
>=20
> Thanks for all the help you guys.
>=20
> Steve Izett
> Perth Western Australia
> Glasair Super IIRG Renesis 4 port RD1C EC2 EM3
>=20
>=20
>=20
>=20
>=20
>=20
>=20
>=20
> > On 7 Aug 2020, at 2:25 pm, William Jepson wrjjrs@gmail.com =
<flyrotary@lancaironline.net> wrote:
> >=20
> > Stephen,=20
> > The answer to one of your questions is easy. A fast cruise RPM =
should be 6000. Mazda did many instrumented runs and found that 6000 rpm =
was a sweet spot where the dynamics balanced perfectly. At 6000 there is =
almost no load on the bearings. The rotary would run at that RPM =
indefinitely. If you have more power at higher speeds you can use that =
for maximum speed. Those RPMs are eshaft RPMs not propeller.
> > Bill
> >=20
> > On Thu, Aug 6, 2020 at 4:15 PM Stephen Izett stephen.izett@gmail.com =
<flyrotary@lancaironline.net> wrote:
> > Hi Guys
> >=20
> > Thanks for all the feedback.
> > I think I didn=E2=80=99t explain my objective clearly enough.
> >=20
> > Some questions:
> > 1. Given I have variable pitch, what combination of MAP and RPM =
should I climb or cruise at? With fixed pitch I dont suppose you think =
in these terms.
> > So should I be Climbings at WOT & 7000rpm OR WOT & 6300rpm Best =
Power Mixture.
> >=20
> > I think Lynn best understood my intention of trying to use the =
flight as a dyne - I didn=E2=80=99t realise the complexity of the =
relationship of mixture and timing at various settings, thanks Lynn.
> > I thought by keeping WOT and mixture constant I might ascertain a =
maximum efficiency combination for MAP/RPM.
> >=20
> > I=E2=80=99d like a combination for max power. I=E2=80=99m thinking =
identified by higher fuel burn and IAS for the climb, and=20
> > a max efficiency/ecconomy combination for cruise identified by best =
miles per gallon.
> >=20
> > I thought our Renesis with our modified OEM (shortened) manifold but =
no variable intake valves etc. would have a distinctive peak at =
~6400-6600rpm.
> >=20
> > 2. I=E2=80=99m finding tuning the EC2 (objective being EC provides =
constant mixture across the flight envelope) is dependant on the =
combination I choose to tune it at.=20
> > Eg. Tune EC2 MCT for one MAP/RPM combination, say a cruise of 18=E2=80=
=9D AND 5000 rpm, then the EC will not be able to provide a constant =
mixture if I then choose 18=E2=80=9D at 6000rpm.
> > My EC2 has Tracy=E2=80=99s 8 table setup but fueling requirements =
given the extra permutations provided by the variable pitch prop =
(climbing that hill - which gear should I use - 3rd 4th or 5th??)=20
> > appears to stretch its inherent capabilities. So I want a plan for =
what MAP/RPM I will use and then adjust/tune the EC MCT for that =
combination.
> >=20
> > Thanks again guys.
> >=20
> > Steve Izett
> >=20
> >=20
> >  all is nice if you fly that combination. If I then choose ab
> >=20
> > > On 7 Aug 2020, at 6:16 am, lehanover lehanover@aol.com =
<flyrotary@lancaironline.net> wrote:
> > >=20
> > > Your thinking is correct. Control full throttle RPM with load. =
Then experiment always at that particular RPM until you have whatever =
data point you were after. Everything affects everything so it may be =
that (for example) advancing ignition timing at one RPM adds power but =
at another RPM reduces power. A rich mixture at one RPM may increase =
power but reduce power at another RPM. To recover even similar data on =
consecutive days is difficult. The SAE has some charts that produce a =
multiplier to account for density temperature and so on. Required to =
compare results day to day. It takes a long time to collect good =
data..........
> > >=20
> > > Lynn E. Hanover =20
> > >=20
> > >=20
> > >=20
> > > =
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> >=20
> >=20
> > --
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