From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] diffuser re-shaping?
Date: Mon, 22 Feb 2021 06:07:07 +0800
References: <list-1241791@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
In-Reply-To: <list-1241791@logan.com>
Message-Id: <E5A8ACF9-70EE-4B5C-9104-F376B328353E@gmail.com>

Hi M
I take it you mean the diffuser shape,
I don=E2=80=99t unfortunately. I should have taken some.

I=E2=80=99ll try and remember to take some this week when I=E2=80=99m =
hoping to make a small shape change and fly a short test flight to get =
the data.
Its forecast to be a warm one this Friday, 97F. So it will be a good =
test of the system.

Steve

> On 22 Feb 2021, at 2:15 am, Marc Wiese cardmarc@charter.net =
<flyrotary@lancaironline.net> wrote:
>=20
> Steve,
> Any before and after pictures?
> M
>=20
> Sent from my iPad
>=20
>> On Feb 21, 2021, at 1:49 AM, Stephen Izett stephen.izett@gmail.com =
<flyrotary@lancaironline.net> wrote:
>>=20
>> =EF=BB=BFHi Finn
>>=20
>> I see that I was reading your water temps wrongly. You were a little =
warmer than I first thought.
>>=20
>> The pressure transducers I am using are MPX10=E2=80=99s. I=E2=80=99m =
using 5 that I purchased on eBay. They are probably not true Freescale =
units but Chinese ripoff=E2=80=99s I=E2=80=99m guessing.
>>=20
>> I started wiring them directly to the EGT inputs with the dynon =
providing the 5v supply.
>> =46rom memory Ive now added 1K in each leg.
>> I just used Cat 5 twisted pair cable so the signals are noisy but =
readable.
>> Engine Monitor is in the cockpit while box of stacked transducers are =
under the cowl in the heat.
>> I=E2=80=99m using them with the differential inputs across the face 4 =
inches in from each corner and one in the middle of the core.
>> Wish I had a bunch more for higher resolution of the face, but this =
gives me some picture of the pressures.
>>=20
>> A couple of issues:
>> 1. When I tried to calibrate them with a water manometer to read =
inches of water on the Dynon they max=E2=80=99d out at about 6 inches =
H2O. The data sheet says 1.45 psi which I thought was 40 inches of H2O.
>> I=E2=80=99m just not sure what the EGT input circuitry thinks of the =
transducers output impedance etc. or the temp compensation.
>> 2. Ive had issues with a couple of the transducers now in flight. As =
in the data going haywire. Sometimes providing constant data but then at =
other times all over the shop.
>> I thought it was temp related, however I=E2=80=99m beginning to =
suspect that there is substantial turbulence inside my diffuser.
>>=20
>> Either way, they still have given me comparative data which has been =
very illuminating.
>> On the last test after squeezing the wedge end really tight the upper =
back transducer reported very low pressure (As in, the diffuser wall is =
now against the radiator face and there is now basically zero flow to =
that 4 x 4=E2=80=9D section - perhaps larger).
>> Having changed the shape of the diffuser, the flow through the front =
of the Rad has improved enormously. The result better cooling than =
previous flight data ever with that back corner section not flowing any =
air!
>> So I=E2=80=99m going to sand off some of the foam in the diffuser and =
open up the end of the wedge slightly, and hope to improve the cooling =
even further.
>>=20
>> Cheers
>>=20
>> Steve
>>=20
>>=20
>>=20
>>=20
>>> On 21 Feb 2021, at 11:50 am, David Leonard wdleonard@gmail.com =
<flyrotary@lancaironline.net> wrote:
>>>=20
>>> Congratulations Finn!
>>> You must be walking on clouds.
>>>=20
>>> I agree that more cooling will make flying more enjoyable for you.  =
Getting cooling capacity at exactly the optimal level is very tricky.  =
So I say error well on the side of excess cooling.  Makes life easier, =
makes flying more relaxing, and the loss in performance is practically =
trivial.
>>>=20
>>> Dave Leonard
>>>=20
>>> On Sat, Feb 20, 2021, 11:25 AM Finn Lassen finn.lassen@verizon.net =
<flyrotary@lancaironline.net> wrote:
>>> N214FL left the ground this morning for an 18 minute flight.
>>>=20
>>> Main concern was engine (water) cooling. As you know, cooling is a =
compromise between drag from unnecessary air through cowling and =
adequate cooling during normal flight conditions. Climbed to 1,500' =
before pulling back on throttle to see if coolant temp would stop =
rising. It did. Still, I think I erred in too small fluid inlet openings =
in the A/C evaporator cores I used for radiators. Some more work in that =
area is in my future before hot days arrive.
>>>=20
>>> Cut the flight short due to a bit of smoke (didn't smell anything) =
briefly observed low in the cockpit at full throttle later in the =
flight. To be investigated.=20
>>>=20
>>> Van's RV-4 with Mazda 13-B Renesis (RX-8) stock engine.
>>> RWS 2.87:1 Propeller Speed Reduction Unit
>>> RWS Engine Controller and Monitor (modified)
>>> Performance Propeller 76x88
>>> Empty Gross: Approx 926 lbs.
>>>=20
>>> Engine log attached. Unzip and open with Excel.
>>>=20
>>> WTALR: Water temp after left radiator
>>> WTARR: Water temp after right radiator
>>> Use EGT and CHT Ref to compare to OAT and adjust accordingly.
>>>=20
>>> Finn
>>>=20
>>>=20
>>>=20
>>>=20
>>> This email has been checked for viruses by Avast antivirus software.=20=

>>> www.avast.com
>>>=20
>>>=20
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>>=20
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