Return-Path: Received: from mail.theofficenet.com ([65.166.240.5] verified) by logan.com (CommuniGate Pro SMTP 4.2b8) with SMTP id 324239 for flyrotary@lancaironline.net; Fri, 16 Jul 2004 21:50:43 -0400 Received-SPF: error receiver=logan.com; client-ip=65.166.240.5; envelope-from=jackoford@theofficenet.com Received: (qmail 30076 invoked from network); 17 Jul 2004 01:36:57 -0000 Received: from ip-66-45-202-213.nw-tel.com (HELO jack) (66.45.202.213) by mail.theofficenet.com with SMTP; 17 Jul 2004 01:36:57 -0000 Message-ID: <001301c46ba0$611f5800$d5ca2d42@jack> From: "Jack Ford" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: 11th test flight Date: Fri, 16 Jul 2004 18:50:02 -0700 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0010_01C46B65.B4079040" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2800.1106 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 This is a multi-part message in MIME format. ------=_NextPart_000_0010_01C46B65.B4079040 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable You dasn't ever want to run straight H2O in your cooling system. I just went out to the shop and checked a container label for engine = coolant (Wal-Mart variety). Sez boiling point for 50/50 mixture with H2O = is 265 deg.F. Put a 16 psi cap on that and it goes up some more. If coolant and lubricant failure are the criteria for establishing = redline temps, my post of the other day is valid. I think 210-220 degree temps should be good running temps, not redlines. = Modern (Post model A) engines run more efficiently at those = temperatures. But I'd still like to hear an opinion from a 13b authority or two if = there are other criteria for coolant and oil temperature limits. FWIW, again, Jack Ford ----- Original Message -----=20 From: Dale Smith=20 To: Rotary motors in aircraft=20 Sent: Friday, July 16, 2004 4:18 PM Subject: [FlyRotary] Re: 11th test flight Steve Brooks wrote: I made a test flight today with the new scoop, but also wit cooler OAT = (70F) than I've seen in the last couple weeks. I flew for 6 tenths of an hour with temperatures for the oil at 207 and coolant 200 stabilized at 4700 RPMs. I increased the throttle to 5300 RPMs and the coolant stayed put, = and the oil increased by only 3 degrees. I was about 1500 AGL for the = entire flight. I did descend a few hundred feet and climb a few hundred feet to watch the temperatures, but usually was flying a level circle around the airport. I reduced the throttle to 4300, and maintained level flight at about 105 kts. Oil dropped to 195 and coolant to 190. I guess that the good news is the I could fly all day at those = temperatures, and I never saw any temperatures higher than 210, though I really didn't = do an extended climb. I really didn't push level cruise higher than 5300 = (135 kts), but the temperatures seemed to be holding, and actually the oil dropped a degree after letting it stabilize a couple of minutes. The bad news is that the scoop appears to be costing me about 10 kts, = which I was expecting. I also don't have any wheel pants yet on the main = gear, so it's not like I'm out to win any speed test at this point anyways. My = oil continues to run higher than the coolant which indicates to me that I = need to do some more baffling to divert more air to the oil cooler. I also have not done any filling or finishing to the scoop, so it's = surface is more like sandpaper right now. Finishing it will probably improve = air flow some more, and also reduce some of the drag. I left the scoop on = the plane for now, so that I can hopefully get another flight in tomorrow morning. My plan tomorrow is to climb up to 5000' and see what I get = there. Then I'll remove the scoop, which takes about 5 minutes, and bring it = home for some filling and sanding. And after a few more flights, and more filling and sanding, some primer and paint. I am still looking at this as a "hot weather scoop". My plan is to = remove it during cool weather, and re-install it for June-August. I mount the scoop using 6 10-32 SS screws into nutplates embedded in the landing = gear cover, plus 2 of the screws that mount the landing gear cover to the fuselage. It's not likely to come off on its own. Steve Brooks Cozy MKIV Turbo Rotary - 6.3 hours and counting Steve ... re: the above underlined. I would say that what you have is just fine regarding your oil temp. = Remember that the "delta T" between where you are running and the = temperature at where it quits working is quite high. Especially if you = are using synthetic oil. Molbil I keeps lubricating quite well up past = 400 degrees and beyond. Thus, if you are running temps near 200 = degrees you have near a 200 degree temp spread (delta T) between what = the oil can take away and what it IS taking away in BTU's of heat = dissipation in a stable system. That is a pretty fat safety margin, = when you figure you can run 100 degrees hotter than what you are now and = still have 100 degrees left before lubrication failure is imminent. = Obviously, lower is better. Water cooling now is a different story. operating coolant at temps = near 200 while water boils at 212 ... gives you a delta T of just 12 = degrees to play with. I know you can kick it up by anti-freeze, = pressure on the system, etc. etc. but the bottom line is that you have = a lot narrower delta T range to deal with, and you are always working = the system a lot closer to near it's maximum potential for heat = dissipation. Just a thought, Dale Smith ------=_NextPart_000_0010_01C46B65.B4079040 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
You dasn't ever want to run = straight H2O in=20 your cooling system.
I just went out to the shop and checked = a container=20 label for engine coolant (Wal-Mart variety). Sez boiling point for 50/50 = mixture=20 with H2O is 265 deg.F.
Put a 16 psi cap on that and it goes up = some=20 more.
If coolant and lubricant = failure are the=20 criteria for establishing redline temps,  my post of the other day is valid.
I think 210-220 degree temps should be = good running=20 temps, not redlines. Modern (Post model A) engines run more efficiently = at those=20 temperatures.
But I'd still like to hear an opinion = from a 13b=20 authority or two if there are other criteria for coolant and oil = temperature=20 limits.
FWIW, again,
Jack Ford
----- Original Message -----
From:=20 Dale=20 Smith
Sent: Friday, July 16, 2004 = 4:18 PM
Subject: [FlyRotary] Re: 11th = test=20 flight

Steve Brooks wrote:
I made a test flight today with the new scoop, but also wit =
cooler OAT (70F)
than I've seen in the last couple weeks.  I flew for 6 tenths of an hour
with temperatures for the oil at 207 and coolant 200 stabilized at 4700
RPMs.  I increased the throttle to 5300 RPMs and the coolant stayed put, =
and
the oil increased by only 3 degrees.  I was about 1500 AGL for the =
entire
flight. I did descend a few hundred feet and climb a few hundred feet to
watch the temperatures, but usually was flying a level circle around the
airport.  I reduced the throttle to 4300, and maintained level flight at
about 105 kts.  Oil dropped to 195 and coolant to 190.

I guess that the good news is the I could fly all day at those =
temperatures,
and I never saw any temperatures higher than 210, though I really didn't =
do
an extended climb.  I really didn't push level cruise higher than 5300 =
(135
kts), but the temperatures seemed to be holding, and actually the oil
dropped a degree after letting it stabilize a couple of minutes.

The bad news is that the scoop appears to be costing me about 10 kts, =
which
I was expecting.  I also don't have any wheel pants yet on the main =
gear, so
it's not like I'm out to win any speed test at this point anyways. =
 My oil
continues to run higher than the coolant which indicates to me that I =
need
to do some more baffling to divert more air to the oil =
cooler.

I also have not done any filling or finishing to the scoop, so it's =
surface
is more like sandpaper right now.  Finishing it will probably improve =
air
flow some more, and also reduce some of the drag.   I left the scoop on =
the
plane for now, so that I can hopefully get another flight in tomorrow
morning.  My plan tomorrow is to climb up to 5000' and see what I get =
there.
Then I'll remove the scoop, which takes about 5 minutes, and bring it =
home
for some filling and sanding.  And after a few more flights, and more
filling and sanding, some primer and paint.

I am still looking at this as a "hot weather scoop".  My plan is to =
remove
it during cool weather, and re-install it for June-August.  I mount the
scoop using 6 10-32 SS screws into nutplates embedded in the landing =
gear
cover, plus 2 of the screws that mount the landing gear cover to the
fuselage.  It's not likely to come off on its own.

Steve Brooks
Cozy MKIV
Turbo Rotary - 6.3 hours and counting
Steve ... re: the above underlined.

I = would=20 say that what you have is just fine regarding your oil temp.  = Remember=20 that the "delta T" between where you are running and the temperature = at where=20 it quits working is quite high.  Especially if you are using = synthetic=20 oil.   Molbil I keeps lubricating quite well up past 400 = degrees and=20 beyond.    Thus, if you are running temps near 200 = degrees you=20 have near a 200 degree temp spread (delta T) between what the oil can = take=20 away and what it IS taking away in BTU's of heat dissipation in a = stable=20 system.    That is a pretty fat safety margin, when you = figure=20 you can run 100 degrees hotter than what you are now and still have = 100=20 degrees left before lubrication failure is imminent.  Obviously, = lower is=20 better.

Water cooling now is a different story.   = operating=20 coolant at temps near 200 while water boils at 212 ... gives you a = delta T of=20 just 12 degrees to play with.   I know you can kick it up by = anti-freeze, pressure on the system, etc. etc.   but the = bottom line=20 is that you have a lot narrower delta T range to deal with, and you = are always=20 working the system a lot closer to near it's maximum potential for = heat=20 dissipation.

Just a thought,

Dale=20 Smith

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