Return-Path: Received: from [216.52.245.18] (HELO ispwestemail1.aceweb.net) by logan.com (CommuniGate Pro SMTP 4.1.3) with ESMTP id 2564586 for flyrotary@lancaironline.net; Tue, 02 Sep 2003 07:42:56 -0400 Received: from 7n7z201 (unverified [208.187.45.43]) by ispwestemail1.aceweb.net (Vircom SMTPRS 2.1.258) with SMTP id for ; Tue, 2 Sep 2003 04:43:59 -0700 Message-ID: <008d01c37146$a8d533e0$292dbbd0@7n7z201> From: "William" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: flight #2 and #3 Date: Tue, 2 Sep 2003 06:37:56 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_008A_01C3711C.BEA7D940" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 5.50.4133.2400 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 This is a multi-part message in MIME format. ------=_NextPart_000_008A_01C3711C.BEA7D940 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageRusty, With the use of the special Howe radiator with the oil coolers built = into the tanks, the following MAY need to be checked out. The transfer = of heat from the water to the oil is a function of both the temperature = difference between the water and the oil (delta-T) and the flow rates of = the respective fluids. I.E. if the water is too hot, you obviously = cannot get the oil any cooler than the water, so that becomes limiting. = From your description of behavior, it sounds like your water is cooling = okay. The second factor, the flow rate of the oil and water, could be = negatively affected by the use of the water thermostat. The thermostat = works by restricting the flow of water from the engine through the = radiator, therefore when you reach 180 degrees, it slows down the water = flow. This means that the water flowing by the oil cooler tubes (in the = headers) is going slower. This reduces the *rate* of heat transfer = across the tube (the heat transfer coefficient), so that it may reduce = the cooling effectiveness of the oil cooler. If we take your 240 degree = oil, expose it to the radiator inlet tank (180 degree) you only have 60 = degrees delta T to work with. On the other end of the radiator, you have = much cooler water (any measurement?) which would improve the delta T, = but if the heat transfer coefficient is small, that won't help much. 1. Do you have a drawing and/or specs from the manufacturer that you = could scan and email to me to look at? I would be interested in trying = some heat transfer calculations on the system, but need the physical = layout details to make much sense of it. 2. Try removing the thermostat and running a duplicate flight to see = if the oil temps come down. This would be an indication of velocity = (flow rate) limited heat transfer. Bill Schertz ----- Original Message -----=20 From: Ed Anderson=20 To: Rotary motors in aircraft=20 Sent: Tuesday, September 02, 2003 5:53 AM Subject: [FlyRotary] Re: flight #2 and #3 Rusty, my experience is that (at least the more recent rotary engines) = can withstand oil temps into the engine of up to 240F for at least a = short period of time without causing damage (been there, done that). = Oil Pan temp is going to be quite a bit higher than oil coming out of = the cooler, so I would guestimate that your oil into the engine is at = least 15-20F less (probably more like 20-30F) than oil pan temps. = After all, the oil in your pan (a lot of it) has just come from cooling = the rotors, so is bound to be carrying a lot of heat. =20 I drilled and tapped a 1/8" NPT hole in the fitting where my oil = returns to the engine after going through the cooler for oil temp = sensor. Ed Anderson ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Tuesday, September 02, 2003 12:20 AM Subject: [FlyRotary] Re: flight #2 and #3 But 210 into the engine is gospel from Racing Beat. =20 That's depressing. I may have to call Bruce tomorrow and get his = view on this. I just took another look at the log that Finn posted a = while back, and he did have a period of time where the oil pan temp was = 242, while the oil return from the cooler was 201. If (huge, unproven = "if") this is the case with my engine, then I'll be OK, but I need to = measure the temp into the engine to be sure. I believe the archives = would show that Finn suggested this to me a while back. Guess I should = have listened. =20 If I'm close to staying under 210, I could consider using a 160 = degree thermostat. I know I've seen one of those before, but I can't = find it listed anywhere at the moment. =20 Bill- I'm using a custom made Howe radiator with an oil/water heat = exchanger built into each tank. I have the oil plumbed in series with = the exchangers, such that it goes through the hot tank first, then the = cooler tank. After the second exchanger, it goes through a filter, then = back to the engine. In thinking about this, I might be able to drill = and tap a hole in the top of the spin on filter bracket for a temp = sensor. I'll have to take a closer look at that. My goal was to not = have to have a separate air/oil cooler, but rest assured, the big ugly = cowl has room for one if needed. =20 Rusty ------=_NextPart_000_008A_01C3711C.BEA7D940 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Rusty,
With the use of the special Howe = radiator with the=20 oil coolers built into the tanks, the following MAY need to be checked=20 out.  The transfer of heat from the water to the oil is a function = of both=20 the temperature difference between the water and the oil (delta-T) and = the flow=20 rates of the respective fluids.  I.E. if the water is too hot, you=20 obviously cannot get the oil any cooler than the water, so that becomes=20 limiting. From your description of behavior, it sounds like your water = is=20 cooling okay.
 
The second factor, the flow rate of the = oil and=20 water, could be negatively affected by the use of the water thermostat. = The=20 thermostat works by restricting the flow of water from the engine = through the=20 radiator, therefore when you reach 180 degrees, it slows down the water = flow.=20 This means that the water flowing by the oil cooler tubes (in the = headers) is=20 going slower. This reduces the *rate* of heat transfer across the tube = (the heat=20 transfer coefficient), so that it may reduce the cooling effectiveness = of the=20 oil cooler.  If we take your 240 degree oil, expose it to the = radiator=20 inlet tank (180 degree) you only have 60 degrees delta T to work with. = On the=20 other end of the radiator, you have much cooler water (any measurement?) = which=20 would improve the delta T, but if the heat transfer coefficient is = small, that=20 won't help much.
 
1.    Do you have a = drawing and/or=20 specs from the manufacturer that you could scan and email to me to look = at? I=20 would be interested in trying some heat transfer calculations on the = system, but=20 need the physical layout details to make much sense of it.
 
2.    Try removing the = thermostat=20 and running a duplicate flight to see if the oil temps come down. This = would be=20 an indication of velocity (flow rate) limited heat = transfer.
 
Bill Schertz
----- Original Message -----
From:=20 Ed=20 Anderson
Sent: Tuesday, September 02, = 2003 5:53=20 AM
Subject: [FlyRotary] Re: flight = #2 and=20 #3

Rusty, my experience is that (at = least the more=20 recent rotary engines) can withstand oil temps into the engine of up = to 240F=20 for at least a short period of time without causing damage (been = there, done=20 that).  Oil Pan temp is going to be quite a bit higher than oil = coming=20 out of the cooler, so I would guestimate that your oil into the engine = is at=20 least 15-20F less (probably more like 20-30F)  than oil pan = temps. =20 After all, the oil in your pan (a lot of it) has just come from = cooling the=20 rotors, so is bound to be carrying a lot of heat. 
 
I drilled and tapped a 1/8" NPT hole = in the=20 fitting where my oil returns to the engine after going through the = cooler for=20 oil temp sensor.
 
Ed Anderson
----- Original Message -----
From:=20 Russell=20 Duffy
To: Rotary motors in = aircraft=20
Sent: Tuesday, September 02, = 2003 12:20=20 AM
Subject: [FlyRotary] Re: = flight #2 and=20 #3

But 210 into the engine is gospel from Racing Beat.  
 
That's=20 depressing.  I may have to call Bruce tomorrow and get = his view on=20 this.  I just took another look at the log that Finn = posted a=20 while back, and he did have a period of time where the oil pan temp = was 242,=20 while the oil return from the cooler was 201.  If (huge, = unproven "if")=20 this is the case with my engine, then I'll be OK, but I need to = measure the=20 temp into the engine to be sure.  I believe the archives would = show=20 that Finn suggested this to me a while back.  Guess I should = have=20 listened.  
 
If I'm close to staying under 210, I could = consider using=20 a 160 degree thermostat.  I know I've seen one of those before, = but I=20 can't find it listed anywhere at the moment. =20  
 
Bill-=20 I'm using a custom made Howe radiator with an oil/water = heat=20 exchanger built into each tank.  I have the oil plumbed in = series=20 with the exchangers, such that it goes = through the hot tank=20 first, then the cooler tank.  After the second exchanger, it = goes=20 through a filter, then back to the engine.  In thinking about = this, I=20 might be able to drill and tap a hole in the top of the spin on=20 filter bracket for a temp sensor.  I'll have to take a = closer look=20 at that.  My goal was to not have to have a separate = air/oil=20 cooler, but rest assured, the big ugly cowl has room for one if=20 needed. 
 
Rusty
 
 
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