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 09:30:16 +0800
References: <list-617373@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-617373@logan.com>
Message-Id: <2FBA7A4E-2702-4F3A-9880-DD7FC4039C42@gmail.com>

Thanks Lynn.

Steve

> On 8 Aug 2020, at 9:11 am, lehanover lehanover@aol.com =
<flyrotary@lancaironline.net> wrote:
>=20
> Not your fault.    I am old and easily confused.......
>=20
> After each dyno pass, you compare each number recovered near or in the =
inlet tract wherever your fresh air supply is recovered. So as to =
establish the "Weather" or air conditions the engine is "seeing"
>=20
> These are large printed (size C formats) years back. It is now =
probably a spread sheet for very quick calculations. For example you are =
looking for some help at the bottom end to help get out of corners a bit =
better. You change idle jets closer to best power at 7,500 RPM then add =
a bit of accelerator pump. I made movies of the gauges for review. In =
two days of testing (for this one problem) we have many different inlet =
air temps. Many barometric pressures and many humidity readings. So each =
pass produces a different raw HP
> reading. You look on the SAE chart for the number you just recovered =
and follow the column to the SAE correction number temp. or pressure or =
humidity and you fill in your home made form with the "NEW" SAE =
multiplier.  Since all of the charts start at sea level each SAE =
multiplier will reduce the raw HP number. But, all of the passes are now =
in the same format as all of the variables are removed. I could get 2 or =
3 good readings using the movies. The throttle is always wide open and =
the test RPM is controlled with a water brake load cell.
>=20
> In most cases your great idea will cost you HP. but every so often =
Jackpot....4 corrected HP.     Modern dynos have this stuff built into =
their computers so the numbers you see are already corrected to sea =
level. In olden times they were not. Lynn E. Hanover   =20
>=20
> In a message dated 8/7/2020 8:29:40 PM Eastern Standard Time, =
flyrotary@lancaironline.net writes:
>=20
> Sorry Lynn. My apologies those figures @ 9500, 7500,6000 and 4500 are =
altitude. Didn=E2=80=99t click that they could also be read as RPM. =
Sorry!
>=20
> Again thanks for the expertise, those things you mention re flow make =
sense of the anomalies.
>=20
> Please excuse my ignorance - SAE tables?
> Right, so convert those numbers back to sea level. Can you explain =
this for me Lynn?
>=20
> Much appreciated.
>=20
> Steve
>=20
> > On 8 Aug 2020, at 8:08 am, lehanover lehanover@aol.com =
<flyrotary@lancaironline.net> wrote:
> >
> > The impossible is possible................
> >
> > Along the way to tuning success you will find that a specific =
combination of facts may appear and disappear within a few RPM.  Such as =
induction tube length VS exhaust system harmonics/back pressure. Every =
RPM would suggest that a specific tuned intake length would be ideal. =
See the Mazda winning 4 rotor and its adjustable length intake runners.  =
Exhaust back pressure may be high at one RPM and nonexistent at another. =
The whole reason for disconnecting the intake and exhaust  in the =
Renesis among other things is to get the tuning down to some form of =
normal (Meet California UHC). Having no overlap is a giant step in that =
direction. The poor exhaust shapes help pollute the incoming charge a =
bit so as to reduce combustion temps and pull back Oxides of Nitrogen. I =
have seen movies of fuel air flowing backwards in an intake runner.    =
When you record what appears to be faulty data do not discard it and =
then see it again the next day.          When you make a change....make =
it a big one so you can see which way that one took you. Never make more =
than one change.  Use the SAE tables to take all of the data down to sea =
level. Before you compare two data sets.  It is a steep learning =
curve......but it will come to you.  I had a fabulous Stuska dyno in my =
shop for years.
> > and a flow bench. I never did learn all I should have.
> >
> > Fixed pitch props (In effect) reduce pitch as air speed through the =
disc increases.  The suggestion that you turned up 9,500 RPM gives me =
chills. What would the tip speeds be then?
> >
> > You can get above 10,000 RPM with 13-B rotors but they must be very =
light and you must look inside after every race because the tend to =
crack when that light. Note that the Renesis rear main bearing is two =
different diameters to allow for that standing sign wave that forms in =
the crank.  Nobody uses Fram filters or lets friends turn over 8,000 RPM
> > Lynn E. Hanover
> >
> > In a message dated 8/7/2020 6:48:47 PM Eastern Standard Time, =
flyrotary@lancaironline.net writes:
> >
> > Hi Charlie and all
> >
> > On the four runs - Speeds were:
> > 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
> >
> > 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
> > 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=99s 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
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > > On 7 Aug 2020, at 10:34 pm, Charlie England ceengland7@gmail.com =
<flyrotary@lancaironline.net> wrote:
> > >
> > > 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.
> > >
> > > 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)?
> > >
> > > What actual speeds are you achieving when this is happening?
> > >
> > > Refresh my memory; who's prop (what blades) is it?
> > >
> > > Do engine temps go up as you get above 6750 rpm?
> > >
> > > 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?
> > >
> > > Charlie
> > >
> > > On Fri, Aug 7, 2020 at 9:01 AM Stephen Izett =
stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
> > > Hi Guys.
> > >
> > > 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.
> > >
> > > 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.
> > >
> > > 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
> > > possible when seeking maximum power by manual prop pitch =
adjustment.
> > > A Constant Speed Controller would be nice!
> > >
> > > 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.
> > >
> > > 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
> > > for analysis on the ground.
> > >
> > > I=E2=80=99ve got 7 more hours of Phase #1 testing.
> > > So far both aircraft and engine are really great.
> > >
> > > My friend and test pilot Dawie also demonstrated at the end of =
todays flight - a Lazy Eight, a Roll and Wingover.
> > > I felt sick for the next 3 hours. I don't think aerobatics will be =
in my future.
> > >
> > > Thanks for all the help you guys.
> > >
> > > Steve Izett
> > > Perth Western Australia
> > > Glasair Super IIRG Renesis 4 port RD1C EC2 EM3
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > > On 7 Aug 2020, at 2:25 pm, William Jepson wrjjrs@gmail.com =
<flyrotary@lancaironline.net> wrote:
> > > >
> > > > Stephen,
> > > > 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
> > > >
> > > > On Thu, Aug 6, 2020 at 4:15 PM Stephen Izett =
stephen.izett@gmail.com <flyrotary@lancaironline.net> wrote:
> > > > Hi Guys
> > > >
> > > > Thanks for all the feedback.
> > > > I think I didn=E2=80=99t explain my objective clearly enough.
> > > >
> > > > 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.
> > > >
> > > > 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.
> > > >
> > > > 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
> > > > a max efficiency/ecconomy combination for cruise identified by =
best miles per gallon.
> > > >
> > > > I thought our Renesis with our modified OEM (shortened) manifold =
but no variable intake valves etc. would have a distinctive peak at =
~6400-6600rpm.
> > > >
> > > > 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.
> > > > 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??)
> > > > 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.
> > > >
> > > > Thanks again guys.
> > > >
> > > > Steve Izett
> > > >
> > > >
> > > >  all is nice if you fly that combination. If I then choose ab
> > > >
> > > > > On 7 Aug 2020, at 6:16 am, lehanover lehanover@aol.com =
<flyrotary@lancaironline.net> wrote:
> > > > >
> > > > > 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..........
> > > > >
> > > > > Lynn E. Hanover
> > > > >
> > > > >
> > > > >
> > > > > =
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> > > >
> > > >
> > > > --
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