From: "Stephen Izett stephen.izett@gmail.com" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] N214FL RV-4 First Flight
Date: Sun, 21 Feb 2021 15:49:18 +0800
References: <list-1240625@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Message-Id: <76AB10B3-7FD7-4CB4-87EB-48E9B4E1F4D1@gmail.com>

Hi Finn

I see that I was reading your water temps wrongly. You were a little =
warmer than I first thought.

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.

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.

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.

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.

Cheers

Steve


> 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
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> 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
>  =09
> This email has been checked for viruses by Avast antivirus software.=20=

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