Return-Path: Received: from [24.25.9.100] (HELO ms-smtp-01-eri0.southeast.rr.com) by logan.com (CommuniGate Pro SMTP 4.1.8) with ESMTP id 2752256 for flyrotary@lancaironline.net; Wed, 19 Nov 2003 20:21:06 -0500 Received: from o7y6b5 (clt78-020.carolina.rr.com [24.93.78.20]) by ms-smtp-01-eri0.southeast.rr.com (8.12.10/8.12.7) with SMTP id hAK1KIsf016942; Wed, 19 Nov 2003 20:20:20 -0500 (EST) Message-ID: <002a01c3af03$fd7b8840$1702a8c0@WorkGroup> From: "Ed Anderson" To: "Rotary motors in aircraft" Cc: "Paul Conner" References: Subject: Re: [FlyRotary] Re: Core vs Radistor was Re: [FlyRotary] radiator Date: Wed, 19 Nov 2003 20:16:56 -0500 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0027_01C3AEDA.145193E0" 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_0027_01C3AEDA.145193E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MessageBoy, you catch me every time{:>) Thanks for the info Rusty Paul, I calculate out Rusty's radiator to have a volume of 17.5*24.25*2.25 = =3D 964 in^3. Given that he was running a turbo, he would naturally = want/need more cooling capacity than a NA block. So his basic radiator = was approx 50% large in volume than two cores. Since he could produce = up to that much additional power with his turbo, it would appear that = his is sized about right - perhaps a bit on the large size since he = probably would not run under high boost at cruise. =20 I won't go into the different configurations he tried, but it appears = he intends to go with 300 square inch area which with a core depth of = 2.25 inches would give him around 675 in^3 - again fairly close to the = area of two evaporator cores. So again, I would not recommend you spending a lot of money on a = possibly undersized radiator. You can fairly accurately calculate your cooling needs - and your = radiator builder should be able to tell you what size you need. You = probably need to let him know what air flow speed you are expecting it = to provide that performance under. If your radiator builder knows what = he is doing he should be able to take the BTUs you need to reject and = the air flow and calculate the size of radiator you need. On the other = hand, if he is just going to whip you up an "automobile" style radiator, = then you could be stuck with just auto level cooling - perhaps = insufficient for high power continuos operation. My calculations shows that at 175Hp you need to get rid of around 5400 = BTU/Min though the radiator and another 2700 BTU/Min through the oil = cooler. At 160Hp that would be around 5000 and 2500 btu respectively. = Since that is probably worst case (take off and initial climbout), you = might want to size the radiator for your cruise power setting and plan = on a bit of over temp on take off an climb out. At a high power cruise = setting (75%) you would need to cool 131 HP and that would drop your = cooling requirements to around 4000 and 2000 btu/min respectively. Any = descent radiator design shop should be able to work with that type of = information to get you close in size. If you are constrained by the = 17x8 area then perhaps a thicker radiator might be the answer. My = calculations indicates that with a 17X8 you would need a radiator approx = 5" thick to equal the core volume of two evaporator cores. =20 However, a 5" thick radiator would require more dynamic airpressure = (high airspeeds) than our 3.6" thick cores. While I think you would do = Ok with that thickness once airborne and at higher airspeeds, you might = have ground cooling problems unless somehow aiding the airflow though = the radiator. But, at least I am confident you could cool adequately at = cruise. But, in any case, I think your currently planned radiator size is = undersized. FWIW - always keepin mind my knowledge of radiators and = cooling is quite limited. Ed Ed Anderson RV-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com ----- Original Message -----=20 From: Russell Duffy=20 To: Rotary motors in aircraft=20 Sent: Wednesday, November 19, 2003 3:06 PM Subject: [FlyRotary] Re: Core vs Radistor was Re: [FlyRotary] radiator Rusty, what was the size of your radiator and the final determination = about its adequacy? Ed This is revenge for those engine out comments, isn't it :-) I started with a huge radiator, because it had (alleged) oil coolers = in it. The oil coolers didn't work out, and were bypassed, leaving only = water cooling. =20 The rad core width is 17.25, and the length as been changed. Full = length is 24.25" (423 sq in) . The length (not covered) was first = tested at 17.75 " (306 sq in) . The final length (not covered) was = 12.625" (218 sq in) . HALF the original radiator. The core is 2.25" = thick if anyone is doing the math . The other thing to consider is = that the covered portion of the radiator is only covered on the front = side. The back side is open. While there is no air passing through, = turbulent air around the back side will still be removing some heat from = the covered section. There is also a 2" thick oil cooler behind the = uncovered area of radiator, so overall, this is about 4.5" thick. =20 =20 Here is a chart of inlet, rad size, and temps for climb at around 100- = 110 mph. The cheek outlet is fixed at about 66 sq in, and the bottom = opening is about 83 sq in. OAT is ground temp, not in-flight. =20 =20 Date |Inlet (sq in)| Rad core (sq in) | water temp F | oil = temp F | OAT | comments =20 80 | 423 | <180 = (t-stat) | 180 | 80 | bottom outlet open 80 | 306 | <180 = (t-stat) | 180 | 80 | bottom outlet open 10-18 | 48 | 306 | 180 (no = t-stat) | 230 | 75 10-18 | 80 | 218 | 160 = (no-t-stat) | 185 (not max?) | 70 10-19 | 80 | 218 | 160 = (no-t-stat) | 220+ | 80 11-01 | 80 | 218 | 160 (no = t-stat) | 200 | 80 | bottom outlet open=20 My current (changes every week) plan is to go with a core that is = still 2.25" thick, but gives me about 300 sq inches of frontal area. = That will be more than I need now, but since I'll be putting the oil = cooler in front of it to lower the oil temps, I'll need more radiator = than I do now. =20 One final comment about expensive radiators, I wouldn't buy one, = unless you have a very good reason to believe it will be just what you = need. For example, I'll be retiring an $800+ dollar radiator with my = rev-2 cowl. =20 Cheers, Rusty ------=_NextPart_000_0027_01C3AEDA.145193E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Message
Boy, you catch me every = time{:>)
 
Thanks for the info Rusty
 
 Paul,
 
    I calculate out = Rusty's radiator=20 to have a volume of 17.5*24.25*2.25 =3D 964 in^3.  Given that he = was running=20 a turbo, he would naturally want/need more cooling capacity than a NA=20 block.  So his basic radiator was approx 50% large in volume than = two=20 cores.  Since he could produce up to that much additional power = with his=20 turbo, it would appear that his is sized about right - perhaps a bit on = the=20 large size since he probably would not run under high boost at=20 cruise. 
 
  I won't go into the different = configurations=20 he tried, but it appears he intends to go with 300 square inch area = which with a=20 core depth of 2.25 inches would give him around 675 in^3 - again fairly = close to=20 the area of two evaporator cores.
 
 So again, I would not recommend = you spending=20 a lot of money on a possibly undersized radiator.
You can fairly accurately calculate = your cooling=20 needs - and your radiator builder should be able to tell you what size = you=20 need.  You probably need to let him know what air flow speed you = are=20 expecting it to provide that performance under.  If your radiator = builder=20 knows what he is doing he should be able to take the BTUs you need to = reject and=20 the air flow and calculate the size of radiator you need.  On the = other=20 hand, if he is just going to whip you up an "automobile" style radiator, = then=20 you could be stuck with just auto level cooling - perhaps insufficient = for high=20 power continuos operation.
 
My calculations shows that at 175Hp you = need to get=20 rid of around 5400 BTU/Min though the radiator and another 2700 BTU/Min = through=20 the oil cooler.  At 160Hp that would be around 5000 and 2500 btu=20 respectively.  Since that is probably worst case (take off and = initial=20 climbout), you might want to size the radiator for your cruise power = setting and=20 plan on a bit of over temp on take off an climb out.  At a high = power=20 cruise setting (75%) you would need to cool 131 HP and that would drop = your=20 cooling requirements to around 4000 and 2000 btu/min respectively.  = Any descent radiator design shop should be able to work with that = type of=20 information to get you close in size.  If you are constrained by = the 17x8=20 area then perhaps a thicker radiator might be the  answer.  My = calculations indicates that with a 17X8 you would need a radiator approx = 5"=20 thick to equal the core volume of two evaporator cores.  =
 
However, a 5" thick radiator would = require more=20 dynamic airpressure (high airspeeds) than our 3.6" thick cores.  = While I=20 think you would do Ok with that thickness once airborne and at higher = airspeeds,=20 you might have ground cooling problems unless somehow aiding the airflow = though=20 the radiator.  But, at least I am confident you could cool = adequately at=20 cruise.
 
But, in any case, I think your = currently planned=20 radiator size is undersized.  FWIW - always keepin mind my = knowledge=20 of radiators and cooling is quite limited.
 
 
Ed
 
Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
eanderson@carolina.rr.com
----- Original Message -----
From:=20 Russell=20 Duffy
Sent: Wednesday, November 19, = 2003 3:06=20 PM
Subject: [FlyRotary] Re: Core = vs Radistor=20 was Re: [FlyRotary] radiator

 Rusty, what was the size of = your radiator=20 and the final determination about its adequacy?
 
Ed
 
 
This is=20 revenge for those engine out comments, isn't it = :-)
 
I started=20 with a huge radiator, because it had (alleged) oil coolers in = it. =20 The oil coolers didn't work out, and were bypassed, leaving only = water=20 cooling.   
 

The rad core width is 17.25, and the length as been=20 changed.  Full length is = 24.25=94  (423 sq = in) .  The length (not = covered)  was first tested = at 17.75 "   (306 sq in) .  The final length (not = covered) was=20 12.625=94  (218 sq = in) .  HALF the original = radiator.  The core is 2.25=94 thick if = anyone is=20 doing the math .   The=20 other thing to consider is that the covered portion of the radiator is = only=20 covered on the front side.  The back side is open.  While = there is=20 no air passing through, turbulent air around the back side will still = be=20 removing some heat from the covered section.  There is also = a 2"=20 thick oil cooler behind the uncovered area of radiator, so = overall, this=20 is about 4.5" thick.   

 

Here is a chart of inlet, rad size, and temps for = climb at=20 around 100- 110 = mph.   The cheek outlet is fixed at = about 66=20 sq in,  and the bottom = opening is=20 about 83 sq in.   OAT is=20 ground temp, not in-flight.   

 

Date   =20 |Inlet (sq in)|  = Rad core=20 (sq in)  |  water temp F     |  oil temp F         | OAT = |=20 comments

 

           =20  80              | =20 423             &n= bsp;        |  <180 (t-stat)     |  180                    |  80    |  bottom outlet = open

           &n= bsp;=20 80            &n= bsp; | =20 306             &n= bsp;        |  <180 (t-stat)     |  180            &n= bsp;       |  80    |  bottom outlet = open

10-18 | 48            &n= bsp;  | =20 306            &n= bsp;         | =20 180 (no t-stat)  |  230                    |  75

10-18 | 80            &n= bsp;  | =20 218            &n= bsp;         | =20 160 (no-t-stat)  = |  185 (not max?)  |  70

10-19 | 80      =          |  218           &n= bsp;         =20 |  160 = (no-t-stat)  |  220+         =20         |  80

11-01 | 80           &n= bsp;  =20 |  218           &n= bsp;         =20 |  160 (no = t-stat)  |  200           &n= bsp;        =20 |  80   |  bottom outlet open 

 

My current (changes = every week)=20 plan is to go with a core that is still 2.25" thick, but gives me = about 300 sq=20 inches of frontal area.  That will be more than I need now, but=20 since I'll be putting the oil cooler in front of it to lower the = oil=20 temps, I'll need more radiator than I do=20 now.  

 

One final comment = about expensive=20 radiators, I wouldn't buy one, unless you have a very good reason to = believe=20 it will be just what you need.  For example, I'll be retiring an = $800+=20 dollar radiator with my rev-2 cowl. 

 

Cheers,

Rusty

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