X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from poplet2.per.eftel.com ([203.24.100.45] verified) by logan.com (CommuniGate Pro SMTP 5.3.6) with ESMTP id 4245389 for flyrotary@lancaironline.net; Mon, 03 May 2010 03:48:29 -0400 Received-SPF: none receiver=logan.com; client-ip=203.24.100.45; envelope-from=lendich@aanet.com.au Received: from sv1-1.aanet.com.au (mail.aanet.com.au [203.24.100.34]) by poplet2.per.eftel.com (Postfix) with ESMTP id 5F21C173805 for ; Mon, 3 May 2010 15:47:48 +0800 (WST) Received: from ownerf1fc517b8 (203.171.92.134.static.rev.aanet.com.au [203.171.92.134]) by sv1-1.aanet.com.au (Postfix) with SMTP id E3956BEC049 for ; Mon, 3 May 2010 15:47:34 +0800 (WST) Message-ID: <6FA35185DFA742B4821F9231A03EC902@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Augmentors (was Re: 20B RV-8 cooling results) Date: Mon, 3 May 2010 17:47:35 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_001C_01CAEAE8.B6FDA970" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5843 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 100502-1, 05/02/2010), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_001C_01CAEAE8.B6FDA970 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Mike, My motto is " Aim for perfection" with the proviso of " always be = prepared to accept a little less" George (down under) Ed/All, I may have been a bit harsh. I like the augmentor concept. But there = are a lot of these good ideas that either don't pan out in practice or = as you say, are not worth the effort. I started building my RV in 1996. Finished the airframe construction = in about 2000. First flight came 9 years later and most of that 9 years = was spent on engine installation thinking that I was smarter than Tracy = (I'm not) and had a "better idea". A number of people (Dave Leonard and = Chuck Dunlap among them) pointed out how much time I was wasting and in = hindsight they were totally correct. My recommendation for most people still in the building phase. If you = want to fly and want to minimize the chances of problems, copy an = existing installation. If your goal is experimentation and you don't = mind adding years to your build and risk during the early flight test = period, go for it. Remember, perfect is the enemy of good enough. Mike Wills From: Ed Anderson=20 Sent: Sunday, May 02, 2010 5:42 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: Augmentors (was Re: 20B RV-8 cooling results) You're Welcome, Mike, =20 I did not make my point clearly - While its clear exhaust = augmentation can work , the question is - will the benefit be worth the = cost in most cases?. In effect, adding band aids trying to solve say - = a fundamentally cooling challenged installation is likely to be = unproductive in the long run, than say - investment in fixing and/or = "tuning" your cooling system =20 I am not against exhaust augmentation - I just question the return on = invest for MOST cases. =20 =20 I am all for experimentation - just think that expectations should be = realistic (on the other hand that requirement will exclude most of us = from this "Hobby" {:>)). =20 Best Regards =20 Ed =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm -------------------------------------------------------------------------= ----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Mike Wills Sent: Sunday, May 02, 2010 12:43 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Augmentors (was Re: 20B RV-8 cooling results) =20 Ed, =20 Thanks for the input - always valued. I question whether the augmentor = would help at all on the ground given the relatively low power settings. = Low exhaust flow trying to drag exit air through a constricted tube = would possibly cool worse on the ground than a conventional exit. =20 You said "there's no question that the exhaust augmentation can work = if done properly...". If you mean there is no question that effective = cooling can be had in an installation using augmentors, I agree. Again, = C-310 and T-34 are examples. But if you mean that there is no question = that exhaust augmentation can provide effective cooling, reduce cooling = drag with a consequent increase in airplane performance, and also = reduce, not increase noise and weight, I'd ask you to cite examples. I = know of none. =20 Mike Wills=20 =20 From: Ed Anderson=20 Sent: Saturday, May 01, 2010 6:05 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: 20B RV-8 cooling results =20 Hi Mike, =20 The theory indicates that once you get the inlet/diffuser combination = worked out - the inlet size should be in the range of from 25 - 40% of = core frontal area. After than, it's actually the exit conditions that = dominated the air flow through the core/cowl. A streamline duct = diffuser (K&W) is the most efficient practical diffuser (at least that I = have come across) - the theory behind it is to keep the air flow energy = (velocity) high until just before you expand the duct area in front of = the core to convert the dynamic energy to a localized pressure increase. = From what I have read, it appears that smoothness and preventing air = flow separation from the duct walls near the inlet is of major = importance. Any disturbance there creates an expanding "shadow" of = disturbed air which impinges on the core and reduces the effectiveness = of that area. So prevent flow separation is one of the key challenges. = =20 I developed my "Pinched" ducts for short run ducts (the streamline = duct requires something like 16" for cores our nominal size for optimum = performance). The ideal behind my "Pinched" ducts is to speed up the = airflow through the pinched area giving the boundary layer of the flow = more energy to stay attached to the duct walls as it makes the curve = just before the core. Any separation that does happened is much closer = to the core and generally up near the edges and corners - where the core = is not particularly effective in the first place. Been flying with them = for over 5 years and they do the job for my installation - however, just = about any, smooth flowing duct will add to cooling effectiveness - sharp = discontinuities generally do not help. =20 There is no question that the exhaust augmentation can work if done = properly, the question in my mind is whether there are easier ways to = accomplish the desired results. It's my opinion (have not tried one) is = that if it were easy to achieve success and there were major benefits, = we would be seeing them on many more installations. The one's I have = read about that seem to be successful were not what I would call simply = installations. Most have a long tunnel of some sort in which the = exhaust is directed out the end causing airflow inside the tunnel to be = accelerated and "dragged" along and out from under the cowl. In many = cowls that presents a considerable challenge to fabricate - as such = things as motor mounts and hardware have a way of getting in the = way.{:>) =20 =20 I can see that Exhaust augmentation might be advantageous for = promoting airflow during taxi and other low speed operations such as = ground run up - if other ways can not be found to do the job. But, if = an installation is not cooling at cruise - then the cooling system = needs work=20 =20 Just an opinion =20 Ed. =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm -------------------------------------------------------------------------= ----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of Mike Wills Sent: Friday, April 30, 2010 10:39 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: 20B RV-8 cooling results =20 Should have mentioned in my previous comment about augmentors, and = related to Ed's comments here regarding positive pressure within the = cowl impacting differential across the core. Cooling is one problem I = have not experienced. And I think part of the reason is that unlike most = of the guys currently flying tractor installations, with my radiator = under the engine, exit air has an unobstructed flow. =20 I think I actually did a pretty lousy job of building an inlet = diffuser. I've never instrumented it and taken any measurements, but = with some tweaking I bet I could reduce the inlet size some without a = negative impact on cooling. I think it works pretty well as is in spite = of the inlet because the exit is good. =20 Mike Wills =20 From: Ed Anderson=20 Sent: Wednesday, April 28, 2010 5:36 AM To: Rotary motors in aircraft=20 Subject: [FlyRotary] Re: 20B RV-8 cooling results =20 Hi George, =20 As you know, taking heat away from your radiator cores requires = sufficient air mass flow - a number of factors affect this - one of the = principle factors is pressure differential across your core. No = pressure differential =3D no flow. The primary positive pressure on the = front side of the core comes from converting dynamic energy of the = moving air into a local static pressure increase in front of the core. = This is basically limited by your airspeed and efficiency of your = duct/diffuser. The back side of your core air flow (in most = installations) exits inside the cowl. Therefore any positive pressure = above ambient under the cowl is going to reduce the pressure = differential across your core. So once you have the best duct/diffuser = you can achieve on the front side of the core - the only thing left to = increase the pressure differential is to reduce the pressure under the = cowl. =20 An extreme example is someone who flies with an opening (such as one = of the typical inlet holes beside the prop) exposed to the air flow. In = effect this hole with little/no resistance to airflow can "pressurize" = the cowl and raise the air pressure behind the radiator cores reducing = the pressure differential and therefore the cooling. Exhaust = augmentation is theoretically a way to reduce the under the cowl = pressure by using the exhaust pulse to "pump" air from under the cowl, = thereby improving the Dp across the core and therefore your cooling. =20 While exhaust augmentation can apparently work - there was a KITPLANE = issue back several years ago on the topic showing several installations = where this was used. However, from what I read (and think I = understand), it takes some carefully planning to get an installation to = work correct and the effort is not trivial. Give the challenges you may = encounter (such as motor mount struts, etc), fabrication of the = augmentation exit, the need to have the exhaust pulse exit at or inside = the cowl (or construct an extended bottom cowl tunnel) means you would = have the bark of a rotary in front of your feet. Also, to gain maximum = advantage of these techniques, it is desirable to have the exhaust = velocity at the maximum - which implies little/no muffling. Having had = my muffler back out one time (at the cowl exit), I can tell you that you = do not want to position the pilot behind the exhaust outlet (in my = opinion). It is much quieter when you have the exhaust exit behind the = position of the pilot {:>). =20 Some few people seem to have been able to achieve some degree of = success, but even in aircraft where you have an engine without the = aggressive bark of the rotary, you seldom see it used. The basic reason = (in my opinion), is that it offers few advantages (cooling wise) that = can not be achieved easier and more reliability by other methods. For = an all out racer where noise and discomfort is secondary, it may have = some benefit. =20 Having said that, it's clear that in some installations it appears to = work well (see KITPLANE issue), but if it were the magic solution, I = think many more folks would be employing it - but, again, just my = opinion. =20 Ed =20 Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://www.dmack.net/mazda/index.html http://www.flyrotary.com/ http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.rotaryaviation.com/Rotorhead%20Truth.htm -------------------------------------------------------------------------= ----- From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] = On Behalf Of George Lendich Sent: Tuesday, April 27, 2010 9:41 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: 20B RV-8 cooling results =20 Ed/ Tracy, Can't say as I understand Tracy's set- up completely, other than it's = toward the lower end of Rad sizes. I was thinking to myself how I could = create a -ve pressure in the rad outlet to create a suction on the Rad. = We all know how the exhaust augmentation works and I was wondering why = we can't do the same thing with the rad outlets by running the rad = outlets inro a larger outlet fed by outside air. At idle the air is fed = by the prop air stream and at level fight it is fed by outside air = stream. The outside air could be could controlled by a butterfly - simple = enough. I know there emphasis on using shutter /flaps to control the = cowl outlet and I believe their good at restricting air flow, but I = don't know if this equates to a good -ve pressure behind the Rad. This = presupposes the Rads are completely enclosed for both inlet and outlet = air. George ( down under) 75% of my cooling problems were solved with the oil cooler change I = did but still needed more margin for hot weather climbs. Made the = decision to not change or enlarge the cooling outlet (that adds drag) = so went ahead and butchered the pretty inlets I made. =20 Ed Anderson's spreadsheet on BTUs & CFM cooling air required was = instrumental in deciding to go this way. It showed that without = negative pressure on the back side of the rads, there would never be = enough cfm to do the job during climb at full throttle. Negative = pressure is what I had when I flew without the cowl on but oh what a = draggy condition that was.=20 The old inlets were 4.5" diameter for the radiator and 4.125" = diameter for oil cooler. New inlets are 5.190" for the rad, and 4.875" dia for the = oil. This may not sound like a lot but it represents a 36% increase in = inlet area. Results were excellent. Oil temp went down 19 degrees at the test = speed (130) and water temp dropped 9 degrees. On 80 degree day and 500 = ft msl the oil temp maxed out at 194F at 210 mph which is way faster = than I would normally go at this altitude. Temp was around 175 at 130. = Oil Temp in climb remained below redline (210) but the temperature = lapse rate today made results not very meaningful. OAT was dropping 14 = degrees a minute at 3000 fpm climb rate.=20 now back to that nasty composite work to pretty up the inlets again. = They look like large stubby pitot tubes now. I hadn't thought of a good name for the RV-8 but a friend in = California recently came up with the winning idea which fit it well. = "Euphoriac" It's a term from a Sci Fi book (Vintage Season) meaning = something which induces euphoria. =20 ------=_NextPart_000_001C_01CAEAE8.B6FDA970 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Mike,
My motto is " Aim for perfection" = with the=20 proviso of " always be prepared to accept a little less"
George (down under)
Ed/All,
 
I may have been a bit harsh. I like the=20 augmentor concept. But there are a lot of these good ideas that = either=20 don=92t pan out in practice or as you say, are not worth the=20 effort.
 
I started building my RV in 1996. Finished = the=20 airframe construction in about 2000. First flight came 9 years later = and most=20 of that 9 years was spent on engine installation thinking = that I was=20 smarter than Tracy (I'm not) and had a "better idea". A number of = people=20 (Dave Leonard and Chuck Dunlap among them) pointed out how much time I = was=20 wasting and in hindsight they were totally correct.
 
My recommendation for most people still in = the=20 building phase. If you want to fly and want to minimize the chances of = problems, copy an existing installation. If your goal is = experimentation and=20 you don=92t mind adding years to your build and risk during the early = flight=20 test period, go for it.
 
Remember, perfect is the enemy of good=20 enough.
 
Mike Wills

Sent: Sunday, May 02, 2010 5:42 AM
Subject: [FlyRotary] Re: Augmentors (was Re: 20B RV-8 = cooling=20 results)

You=92re = Welcome,=20 Mike,

 

I  did = not make=20 my point clearly - While its clear exhaust augmentation can work , the = question is - will the benefit be worth the cost in most cases?.  = In=20 effect, adding band aids trying to solve say - a fundamentally cooling = challenged installation is likely to be unproductive in the long run,=20  than say -   investment in fixing and/or =  =93tuning=94 your=20 cooling system

 

I am not = against=20 exhaust augmentation =96 I just question the return on invest for MOST = cases. 

 

I am all = for=20 experimentation =96 just think that expectations should be realistic = (on the=20 other hand that requirement will exclude most of us from this = =93Hobby=94=20  {:>)).

 

Best=20 Regards

 

Ed

 

Ed=20 Anderson

Rv-6A = N494BW Rotary=20 Powered

Matthews,=20 NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm

From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Mike Wills
Sent: Sunday, May 02, 2010 = 12:43=20 AM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re: = Augmentors (was=20 Re: 20B RV-8 cooling results)

 

Ed,

 

Thanks for the input - = always=20 valued. I question whether the augmentor would help at all on the = ground given=20 the relatively low power settings. Low exhaust flow trying to drag = exit air=20 through a constricted tube would possibly cool worse on the ground = than a=20 conventional exit.

 

You said "there's no = question=20 that the exhaust augmentation can work if done properly...". If you = mean there=20 is no question that effective cooling can be had in an installation = using=20 augmentors, I agree. Again, C-310 and T-34 are examples. But if you = mean that=20 there is no question that exhaust augmentation can provide effective = cooling,=20 reduce cooling drag with a consequent increase in airplane = performance, and=20 also reduce, not increase noise and weight, I'd ask you to cite = examples. I=20 know of none.

 

Mike=20 Wills 

 

From: Ed=20 Anderson

Sent:=20 Saturday, May 01, 2010 6:05 AM

To: Rotary motors in = aircraft=20

Subject:=20 [FlyRotary] Re: 20B RV-8 cooling=20 results

 

Hi=20 Mike,

 

The theory = indicates=20 that once you get the inlet/diffuser combination worked out =96 the = inlet size=20 should be in the range of from 25 =96 40% of core frontal area.  = After=20 than, it=92s actually the exit conditions that dominated the air flow = through=20 the core/cowl.  A streamline duct diffuser (K&W) is the most=20 efficient practical diffuser (at least that I have come across) =96 = the theory=20 behind it is to keep the air flow energy (velocity) high until just = before you=20 expand the duct area in front of the core to convert the dynamic = energy to a=20 localized pressure increase.  From what I have read, it appears = that=20 smoothness and preventing air flow separation from the duct walls near = the=20 inlet is of major importance.  Any disturbance there creates an = expanding=20 =93shadow=94 of disturbed air which impinges on the core and reduces = the=20 effectiveness of that area.  So prevent flow separation is one of = the key=20 challenges. 

 

I developed = my=20 =93Pinched=94 ducts for short run ducts (the streamline duct requires = something=20 like 16=94 for cores our nominal size for optimum performance).  = The ideal=20 behind my =93Pinched=94 ducts is to speed up the airflow through the = pinched area=20 giving the boundary layer of the flow more energy to stay attached to = the duct=20 walls as it makes the curve just before the core.  Any separation = that=20 does happened is much closer to the core and generally up near the = edges and=20 corners =96 where the core is not particularly effective in the first=20 place.  Been flying with them for over 5 years and they do the = job for my=20 installation =96 however, just about any, smooth flowing duct will add = to=20 cooling effectiveness =96 sharp discontinuities generally do not=20 help.

 

There is no = question=20 that the exhaust augmentation can work if done properly, the question = in my=20 mind is whether there are easier ways to accomplish the desired = results. =20 It=92s my opinion (have not tried one) is that if it were easy to = achieve=20 success and there were major benefits, we would be seeing them on many = more=20 installations.  The one=92s I have read about that seem to be = successful=20 were not what I would call simply installations.  Most have a = long tunnel=20 of some sort in which the exhaust is directed out the end causing = airflow=20 inside the tunnel to be accelerated and  =93dragged=94 along and = out from=20 under the cowl.  In many cowls that presents a considerable = challenge to=20 fabricate - as such things as motor mounts and hardware have a way of = getting=20 in the way.{:>) 

 

I can see = that=20 Exhaust augmentation might be advantageous for promoting airflow = during taxi=20 and other low speed operations such as ground run up =96 if other ways = can not=20 be found to do the job.  But, if an installation is not cooling = at cruise=20 =96 then the  cooling system needs work =

 

Just an=20 opinion

 

Ed.

 

Ed=20 Anderson

Rv-6A = N494BW Rotary=20 Powered

Matthews,=20 NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm

From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of Mike Wills
Sent: Friday, April 30, 2010 = 10:39=20 PM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re: 20B = RV-8 cooling=20 results

 

Should have mentioned = in my=20 previous comment about augmentors, and related to Ed's comments here = regarding=20 positive pressure within the cowl impacting differential across the = core.=20 Cooling is one problem I have not experienced. And I think part of the = reason=20 is that unlike most of the guys currently flying tractor = installations, with=20 my radiator under the engine, exit air has an unobstructed=20 flow.

 

I think I actually did = a pretty=20 lousy job of building an inlet diffuser. I've never instrumented it = and taken=20 any measurements, but with some tweaking I bet I could reduce the = inlet size=20 some without a negative impact on cooling. I think it works pretty = well as is=20 in spite of the inlet because the exit is=20 good.

 

Mike=20 Wills

 

From: Ed=20 Anderson

Sent:=20 Wednesday, April 28, 2010 5:36 AM

To: Rotary motors in = aircraft=20

Subject:=20 [FlyRotary] Re: 20B RV-8 cooling=20 results

 

Hi=20 George,

 

As you = know, taking=20 heat away from your radiator cores requires sufficient air mass flow = =96 a=20 number of factors affect this =96 one of the principle factors is = pressure=20 differential across your core.  No pressure differential =3D no = flow. =20 The primary positive pressure on the front side of the core comes from = converting dynamic energy of the moving air into a local static = pressure=20 increase in front of the core.  This is basically limited by your = airspeed and efficiency of your duct/diffuser.  The back side of = your=20 core air flow (in most installations) exits inside the cowl.  = Therefore=20 any positive pressure above ambient under the cowl is going to reduce = the=20 pressure differential across your core.  So once you have the = best=20 duct/diffuser you can achieve on the front side of the core =96 the = only thing=20 left to increase the pressure differential is to reduce the pressure = under the=20 cowl.

 

An extreme = example is=20 someone who flies with an opening (such as one of the typical inlet = holes=20 beside the prop) exposed to the air flow.  In effect this hole = with=20 little/no resistance to airflow can =93pressurize=94 the cowl and = raise the air=20 pressure behind the radiator cores reducing the pressure differential = and=20 therefore the cooling.  Exhaust augmentation is theoretically a = way to=20 reduce the under the cowl pressure by using the exhaust pulse to = =93pump=94 air=20 from under the cowl, thereby improving the Dp across = the core and=20 therefore your cooling.

 

While = exhaust=20 augmentation can apparently work =96 there was a KITPLANE issue back = several=20 years ago on the topic showing several installations where this was=20 used.  However, from what I read (and think I understand), it = takes some=20 carefully planning to get an installation to work correct and the = effort is=20 not trivial.  Give the challenges you may encounter (such as = motor mount=20 struts, etc), fabrication of the augmentation exit,  the need to = have the=20 exhaust pulse exit at or inside the cowl (or construct an extended = bottom cowl=20 tunnel) means you would have the bark of a rotary in front of your = feet. =20 Also, to gain maximum advantage of these techniques, it is desirable = to have=20 the exhaust velocity at the maximum =96 which implies little/no = muffling. =20 Having had my muffler back out one time (at the cowl exit), I can tell = you=20 that you do not want to position the pilot behind the exhaust outlet = (in my=20 opinion).  It is much quieter when you have the exhaust exit = behind the=20 position of the pilot {:>).

 

Some few = people seem=20 to have been able to achieve some degree of success, but even in = aircraft=20 where you have an engine without the aggressive bark of the rotary, = you seldom=20 see it used.  The basic reason (in my opinion), is that it offers = few=20 advantages (cooling wise) that can not be achieved easier and more = reliability=20 by other methods.  For an all out racer where noise and = discomfort is=20 secondary, it may have some benefit.

 

Having said = that,=20 it=92s clear that in some installations it appears to work well (see = KITPLANE=20 issue), but if it were the magic solution, I think many more folks = would be=20 employing it =96 but, again, just my = opinion.

 

Ed

 

Ed=20 Anderson

Rv-6A = N494BW Rotary=20 Powered

Matthews,=20 NC

eanderson@carolina.rr.com

http://www.andersonee.com

http://www.dmack.net/mazda/index.html

http://www.flyrotary.com/

http://members.cox.net/rogersda/rotary/configs.htm#N494BW

http://www.r= otaryaviation.com/Rotorhead%20Truth.htm

From:=20 Rotary motors in aircraft = [mailto:flyrotary@lancaironline.net] On=20 Behalf Of George Lendich
Sent: Tuesday, April 27, 2010 = 9:41=20 PM
To: = Rotary motors in aircraft
Subject: [FlyRotary] Re: 20B = RV-8 cooling=20 results

 

Ed/=20 Tracy,

Can't say as I = understand=20 Tracy's set-=20 up completely, other than it's toward the lower end of Rad sizes. I = was=20 thinking to myself how I could create a -ve pressure in the rad = outlet to=20 create a suction on the Rad. We all know how the exhaust augmentation = works=20 and I was wondering why we can't do the same thing with the rad = outlets by=20 running the rad outlets inro a larger outlet fed by outside air. At = idle the=20 air is fed by the prop air stream and at level fight it is fed by = outside air=20 stream.

The outside air could=20 be could controlled by a butterfly - simple enough. I know there = emphasis=20 on using shutter /flaps to control the cowl outlet and I believe their = good at=20 restricting air flow, but I don't know if this equates to a good -ve = pressure=20 behind the Rad. This presupposes the Rads are completely enclosed for = both=20 inlet and outlet air.

George ( down=20 under)

75% of my cooling problems were solved = with the oil=20 cooler change I did but still needed more margin for hot weather = climbs.=20   Made the decision to not change or enlarge the cooling outlet = (that=20 adds drag)  so went ahead and butchered the pretty inlets I = made. =20
Ed Anderson's spreadsheet on BTUs & CFM cooling air required = was=20 instrumental in deciding to go this way.   It showed that = without=20 negative pressure on the back side of the rads, there would never be = enough=20 cfm to do the job during climb at full throttle.  Negative = pressure is=20 what I had when I flew without the cowl on but oh what a draggy = condition=20 that was.

The old inlets were 4.5" diameter for the radiator = and=20 4.125" diameter for oil cooler.
New inlets=20 are        5.190" for the = rad,  and=20   4.875" dia for the oil.

This may not sound like a lot = but it=20 represents a 36% increase in inlet area.

Results were=20 excellent.  Oil temp went down 19 degrees at the test speed = (130) and=20 water temp dropped 9 degrees.  On 80 degree day and 500 ft msl = the oil=20 temp maxed out at 194F at 210 mph which is way faster than I would = normally=20 go at this altitude.  Temp was around 175 at 130.    = Oil Temp=20 in climb remained below redline (210) but the temperature lapse rate = today=20 made results not very meaningful.  OAT was dropping 14 degrees = a minute=20 at 3000 fpm climb rate.

now back to that nasty composite = work to=20 pretty up the inlets again.  They look like large stubby pitot = tubes=20 now.

I hadn't thought of a good name for the RV-8 but a = friend in=20 California=20 recently came up with the winning idea which fit it well. = "Euphoriac" =20 It's a term from a  Sci Fi book (Vintage Season)  meaning=20 something which induces euphoria. =20 =

------=_NextPart_000_001C_01CAEAE8.B6FDA970--