X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-vw0-f52.google.com ([209.85.212.52] verified) by logan.com (CommuniGate Pro SMTP 5.3.6) with ESMTP id 4240849 for flyrotary@lancaironline.net; Wed, 28 Apr 2010 22:22:37 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.212.52; envelope-from=rwstracy@gmail.com Received: by vws10 with SMTP id 10so1101831vws.25 for ; Wed, 28 Apr 2010 19:22:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:sender:received :in-reply-to:references:date:x-google-sender-auth:message-id:subject :from:to:content-type; bh=ClHAxFRCj+nsZIRZ0pfCE3LEj+8Fxch8uYv5tTuDCG4=; b=sr3yMLQeQtdZ+VGBlcoulsSwjqqiwbsnMKwYqfPMo6IP8f/NznZDrI9PEYW7sa7jlo yRwGX8c9xAxx39CmKnniPcO3+2G00n4GonbG3W6UshjaGIz9y0hcvtAEDeWK9N3FznSZ dChES1gFdK5zc+XH1uRn+XfFo1JJUv4xzL6+E= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; b=QhY2mQnOkXrQgLHOCmZkqDUz/VkSqUDPE4BvgpJYmB25qdUo+MMalnWdqNizvYnAof v2bLT51SeFD8c8b4p84byuWa6/GeFn5xY5BFe8x02Gg9PF5X+5y5WzNMNjybRyIUNByf qseDvF810A38uxhAMGWGpezozLUv/bEQQxCTs= MIME-Version: 1.0 Received: by 10.220.59.203 with SMTP id m11mr5980750vch.236.1272507720810; Wed, 28 Apr 2010 19:22:00 -0700 (PDT) Sender: rwstracy@gmail.com Received: by 10.220.97.212 with HTTP; Wed, 28 Apr 2010 19:22:00 -0700 (PDT) In-Reply-To: References: Date: Wed, 28 Apr 2010 22:22:00 -0400 X-Google-Sender-Auth: 8b7be8ab2e327290 Message-ID: Subject: Re: [FlyRotary] turbo install & ECU glitch From: Tracy Crook To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=e0cb4e887687ac4465048556ca6d --e0cb4e887687ac4465048556ca6d Content-Type: text/plain; charset=ISO-8859-1 Chris: I can only think of one (or 2?) possible reason for the NOP symptom you described (Mode 1 & press Store button). Doing that causes it to go into injector test mode (if the cold start switch is on). If it's going into inj. test, the noise generated by the injectors firing may be corrupting the serial data between EC2 & EM2. This is probably due to the electrical layout, bad grounding scheme, and/or bundling the injector power or injector control leads with the serial data leads. The injector test mode stops when you go back to Mode 0 and the NOP goes away because the data is no longer being corrupted. Other possible reason is a miss wire involving the serial data lines. Note the extra front panel that I told you about in the test report below. If you still think the one in the plane may be bad, try the other one. And try the other controller as well. I programmed it for your engine now. Here's the report I sent you after the EC2 & other service: Hi Chris, Finished the work on drive and ec2s. Here's what I found. The bearing clearance on the drive was at the low end of spec but still acceptable. There was some evidence of some contaminate that put minor scratches in the bearing race and shaft but they polished out easily. Don't know if that had anything to do with the bearing getting tight. It could have been a combination of minimum bearing clearance, a cold day (which reduces clearance) and the oil pump taking a few seconds to prime after sitting awhile. No way to tell for certain. I cleaned up the shaft and line bored the rear shaft bearing to the middle of the specified clearance range and all looks good. Your EC2 tested OK but the front panel had a couple of open circuits. The cold start switch was not working due to a foil being burned open from over current. Can't tell you what caused that but make sure there are no miss-wires on the cold start circuit. The program knob did not work right because a plated through hole that one of the leads was soldered to had broken loose from the circuit path, probably due to mechanical stress. I repaired the opens with jumper wires. Be aware that the injector test mode requires the cold start switch to be on. That's why the EC2 did not appear to work in test mode. Mode 8 (ignition) did work OK on both A & B. The other EC2 also tested OK but it was programmed for a Renesis engine at Rino's request. That's why it wouldn't run on your engine. Do you want me to update it for your engine? (2nd gen EC2 with LS-1 coils). The front panel that was stored inside this ec2 was tested and was OK. The EM2 looks like it's working fine. All the best, Tracy Crook, RWS On Wed, Apr 28, 2010 at 9:59 PM, Chris Barber wrote: > Also, as to the EC2, when I place it into Mode 1 and press the programbutton, the dreaded NOPcomes up blinking. Clears when I take it back to Mode 0. > > Back to searching the archives. Pretty slow on broadband wireless that > keeps me connected in the hangar. Oh well. > > Chris > GSOT > ------------------------------ > *From:* Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf > of Chris Barber [cbarber@texasattorney.net] > *Sent:* Wednesday, April 28, 2010 8:53 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Archives and topic drift....uh, like > this...turboinstall > > Chris, > > Good luck searching the archives. Topic drift is driving me nuts as I try > to find a response Tracy sent me long ago regarding my program knob not > responding. Perhaps it is the program button, but the button is working ok > as a primer button, but I can't get the MAP to change and my engine stalls > when I take it out of Mode 0. Thought it was fixed with its latest trip > to FL a few months ago, but alas, no joy. Seems he said it may be a > ground....so the search continues > > I did mount my turbo today. It is not yet plumbed to the intake yet, but > just the turbo by itself takes a lot of the rotary bark away....mostly prop > noise now. But, kinda moot with out being able to tune properly...due to > the program knob glitch. > > Not sure of how to test if the knob or button are working and it is a > problem somewhere else. > > My cooing seemed pretty good with the turbo. Oil was a bit higher than > water. The turbo IS a wet housing, but it did not seem to be an issue > around idle in Houston...pretty mild day in the 80's. > > All the best, > > Chris Barber > Houston, GSOT > > ------------------------------ > *From:* Rotary motors in aircraft [flyrotary@lancaironline.net] on behalf > of Tracy Crook [tracy@rotaryaviation.com] > *Sent:* Wednesday, April 28, 2010 8:09 PM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Eductor scavenging of radiator outlet, WAS > 20BRV-8 cooling results > > I was talking about the usual methods of decreasing the pressure on > backside of heat exchangers, like very large exit opening, lip on bottom of > cooling exit, cowl flaps that protrude into the slipstream, radiators > mounted naked in the slipstream, etc. I was interested in the eductor > because it was an exception. It does not increase drag if done properly. > It's hard to do properly on the rotary and still have a reasonably quiet > exhaust though.... > > Tracy > > On Wed, Apr 28, 2010 at 5:59 PM, George Lendich wrote: > >> Tracy, >> Like yourself I have been considering the benefits of an Eductor for some >> time, but can't understand why it would cause extra drag. >> >> As a matter of fact I thought it might decrease drag by speeding up the >> rad exit air back up to outside air speed as it exits the cowl. >> >> Can you explain the reasons behind the increased drag issues. >> George (down under) >> >> *"Since the draw of air via low pressure on the output side seems to be >> key, I wonder if an eductor type of scenario would work."* >> >> Sometimes I doubt my ability to get a point across clearly :-) An eductor >> can be made to help (but very hard to do as Ed pointed out) but the point I >> was trying to make in my original post is that the draw of air on the low >> side is NOT key. You will never get a fraction of the pressure delta with >> low side help (even with an eductor) that you can with the proper inlet and >> diffuser. This is especially true on faster airplanes. A Pietenpol might >> be an exception. >> >> The inlet is what fixed my problem. This is an extreme example but when I >> used low side help, it did cool but the drag caused the fuel consumption to >> increase by 50 - 60% ! at the test speed of 130 mph. That's not a price >> you want to pay. >> >> Tracy >> >> On Wed, Apr 28, 2010 at 9:19 AM, Chris Owens - Rotary > > wrote: >> >>> You know, I don't know if this has been discussed, but the whole pressure >>> differential thing got me thinking of something that I'm surprised I hadn't >>> thought of earlier. Since the draw of air via low pressure on the output >>> side seems to be key, I wonder if an eductor type of scenario would work. >>> >>> Back in my Navy days, we used to use a device called an in-line eductor >>> for dewatering flooded spaces. Similar to a venturi, more or less, you >>> pumped water through it, it created a suction, and it was designed to suck >>> as much water through it as you put into it. 100 gallons per minute input >>> would dewater at 100 gallons per minute with 200 gallons per minute flowing >>> through the output. A representative device is here (perhaps not for fluid >>> use, but the concept is similar): >>> >>> http://www.1877eductors.com/eductor_gas_dimensions.htm >>> >>> I presume a similar approach could be taken with a radiator setup, would >>> you think? I imagine it would work well for a center mounted radiator with >>> a centerline, below-the-nose scoop, so one could utilize the cheek inlets to >>> provide source air for the outlet side. >>> >>> ~Chris >>> >>> >>> >>> ------------------------------ >>> *From*: "Ed Anderson" >>> *Sent*: Wednesday, April 28, 2010 7:08 AM >>> *To*: "Rotary motors in aircraft" >>> *Subject*: [FlyRotary] Re: 20B RV-8 cooling results >>> >>> Hi George, >>> >>> >>> >>> 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 = 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. >>> >>> >>> >>> 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. >>> >>> >>> >>> 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 {:>). >>> >>> >>> >>> 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. >>> >>> >>> >>> 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. >>> >>> >>> >>> Ed >>> >>> >>> >>> 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 >>> >>> >>> >>> 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. >>> 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. >>> >>> 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. >>> >>> 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. >>> >>> >>> >> > --e0cb4e887687ac4465048556ca6d Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Chris:
=A0I can only think of one (or 2?) possible reason for the NOP s= ymptom you described (Mode 1 & press Store button).=A0 Doing that cause= s it to go into injector test mode (if the cold start switch is on).=A0 If = it's going into inj. test, the noise generated by the injectors firing = may be corrupting the serial data between EC2 & EM2.=A0 This is probabl= y due to the electrical layout, bad grounding scheme, and/or bundling the i= njector power or injector control leads with the serial data leads.=A0=A0= =A0 The injector test mode stops when you go back to Mode 0 and the NOP goe= s away because the data is no longer being corrupted.

Other possible reason is a miss wire involving the serial data lines.= =A0

Note the extra front panel that I told you about in the test re= port below.=A0 If you still think the one in the plane may be bad, try the = other one.=A0 And try the other controller as well.=A0 I programmed it for = your engine now.=A0

=A0Here's the report I sent you after the EC2 & other service:<= br>
Hi Chris,
=A0=A0 Finished the work on drive and ec2s.=A0=A0 Here&= #39;s what I=20 found.

The bearing clearance on the drive was at the low end of=20 spec but still acceptable.=A0 There was some evidence of some contaminate= =20 that put minor scratches in the bearing race and shaft but they polished out easily.=A0 Don't know if that had anything to do with the bearing= =20 getting tight.=A0 It could have been a combination of minimum bearing=20 clearance, a cold day (which reduces clearance)= =20 and the oil pump taking a few seconds to prime after sitting awhile.=A0=A0= =20 No way to tell for certain.

=A0I cleaned up the shaft and line bored the rear shaft bearing to the middle of the specified clearance range and all looks good.

Your EC2 tested OK but the front panel had a couple of open circuits.=A0 The cold start switch was not= =20 working due to a foil being burned open from over current.=A0=A0 Can't = tell=20 you what caused that but make sure there are no miss-wires on the cold start circuit. =A0 The=20 program knob did not work right because a plated through hole that one=20 of the leads was soldered to had broken loose from the circuit path,=20 probably due to mechanical stress.=A0 I repaired the opens with jumper=20 wires.=A0

Be aware that the injector test mode requires the co= ld start switch to be on.=A0=A0 That's why the = EC2 did not appear to work in test mode.=A0 Mode 8 (ignition) did work OK on both A & B.

The other EC2 also tested OK but it was programmed=20 for a Renesis engine at Rino's request.=A0 That's why it wouldn'= ;t run on=20 your engine.=A0 Do you want me to update it for your engine?=A0 (2nd gen EC= 2 with LS-1 coils). =A0 The front panel that was stored inside this ec2 was tested and was OK.=A0

The EM2 looks like it's working fine.

All the best,
Tracy Crook,=A0=A0=A0=A0=A0 RWS

On Wed, Apr 28, 2010 at 9:59 PM, Chris Barber <cbarber@texasatto= rney.net> wrote:
Also, as to the EC2, when I place it into Mode 1 and pre= ss the=A0program button, the dreaded=A0NOP comes up bl= inking.=A0 Clears when I take it back to Mode 0.
=A0
Back to searching the archives.=A0 Pretty slow on broadband wireless t= hat keeps me connected in the hangar.=A0 Oh well.
=A0
Chris
From: Rotary motors in aircraft [flyrotary@lancaironline.net] on be= half of Chris Barber [cbarber@texasattorney.net]
Sent: Wednesday, April 28, 2010 8:53 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Archives and topic drift....uh, like this...tur= boinstall

Chris,
=A0
Good luck searching the archives.=A0 Topic drift is driving me = nuts as I try to find a response Tracy sent me long ago=A0regarding my prog= ram knob not responding.=A0 Perhaps it is the program button, but=A0the but= ton=A0is working ok as a primer button, but I can't get the MAP to change and my engine stalls when I take it out = of Mode 0.=A0=A0=A0 Thought it was fixed with its latest trip to FL a few m= onths ago, but alas, no joy.=A0 Seems he said it may be a ground....so the = search continues
=A0
I did mount my turbo today.=A0 It is not yet plumbed to the intake yet= , but just the turbo by itself takes a lot of the rotary bark away....mostl= y prop noise now.=A0 But,=A0kinda moot with out being able to= tune properly...due to the=A0program knob glitch.
=A0
Not sure of how to test if the knob or button are working and it is a = problem somewhere else.=A0 <sigh>
=A0
My cooing seemed pretty good with the turbo.=A0 Oil was a bit higher t= han water.=A0 The turbo IS a wet housing, but it did not seem to be an issu= e around idle in Houston...pretty mild day in the 80's.
=A0
All the best,
=A0
Chris Barber
Houston, GSOT
=A0
From: Rotary motors in aircraft [flyrotary@lancaironline.net] on be= half of Tracy Crook [tracy@rotaryaviation.com]
Sent: Wednesday, April 28, 2010 8:09 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Eductor scavenging of radiator outlet, WAS = 20BRV-8 cooling results

I was talking about the usual methods of decreasing the pressure on ba= ckside of heat exchangers, like very large exit opening, lip on bottom of c= ooling exit, cowl flaps that protrude into the slipstream, radiators mounte= d naked in the slipstream, etc.=A0 I was interested in the eductor because it was an exception.=A0 It does no= t increase drag if done properly.=A0 It's hard to do properly on the ro= tary and still have a reasonably quiet exhaust though....

Tracy

On Wed, Apr 28, 2010 at 5:59 PM, George Lendich = <lendich@aanet= .com.au> wrote:
Tracy,
Like yourself I have been considering = the benefits of an Eductor for some time, but can't understand why it w= ould cause extra drag.
=A0
As a matter of fact I thought it might= decrease drag by speeding up the rad exit air back up to outside air speed= as it exits the cowl.
=A0
Can you explain=A0the reasons behind t= he increased drag issues.
George (down under)
<= i>"Since the draw of air via low pressure on the output side seems to = be key, I wonder if an eductor type of scenario would work."

Sometimes I doubt my ability to get a point across clearly :-)=A0 An educto= r can be made to help (but very hard to do as Ed pointed out)=A0 but the po= int I was trying to make in my original post is that the draw of air on the= low side is NOT key. =A0 You will never get a fraction of the pressure delta with low side help (even with an educ= tor) that you can with the proper inlet and diffuser.=A0=A0 This is especia= lly true on faster airplanes.=A0 A Pietenpol might be an exception.=A0

The inlet is what fixed my problem.=A0 This is an extreme example but when = I used low side help, it did cool but the drag caused the fuel consumption = to increase by 50 - 60% ! at the test speed of 130 mph. =A0 That's not = a price you want to pay.

Tracy

On Wed, Apr 28, 2010 at 9:19 AM, Chris Owens - R= otary <rotary@cmowens.= com> wrote:
Y= ou know, I don't know if this has been discussed, but the whole pressur= e differential thing got me thinking of something that I'm surprised I = hadn't thought of earlier.=A0 Since the draw of air via low pressure on the output side seems to be key, I wonder if an= eductor type of scenario would work.

Back in my Navy days, we used to use a device called an in-line eductor for= dewatering flooded spaces.=A0 Similar to a venturi, more or less, you pump= ed water through it, it created a suction, and it was designed to suck as m= uch water through it as you put into it.=A0 100 gallons per minute input would dewater at 100 gallons per minut= e with 200 gallons per minute flowing through the output.=A0 A representati= ve device is here (perhaps not for fluid use, but the concept is similar):<= br>
http://www.1877eductors.com/eductor_gas_dimensions.htm

I presume a similar approach could be taken with a radiator setup, would yo= u think?=A0 I imagine it would work well for a center mounted radiator with= a centerline, below-the-nose scoop, so one could utilize the cheek inlets = to provide source air for the outlet side.

~Chris



From: "Ed Anderson" <eanderson@carolina.rr.com>
Sent: Wednesday, April 28, 2010 7:08 AM
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net&= gt;
Subject: [FlyRotary] Re: 20B RV-8 cooling results

Hi George,

=A0

As you know, taking heat away from your radiator co= res requires sufficient air mass flow - a number of factors affect this - o= ne of the principle factors is pressure differential across your core.=A0 No pressure differential =3D no flow.=A0= The primary positive pressure on the front side of the core comes from con= verting dynamic energy of the moving air into a local static pressure incre= ase in front of the core.=A0 This is basically limited by your airspeed and efficiency of your duct/diffuser.=A0 The back= side of your core air flow (in most installations) exits inside the cowl.= =A0 Therefore any positive pressure above ambient under the cowl is going t= o reduce the pressure differential across your core.=A0 So once you have the best duct/diffuser you can achieve on t= he front side of the core - the only thing left to increase the pressure di= fferential is to reduce the pressure under the cowl.

=A0

An extreme example is someone who flies with an ope= ning (such as one of the typical inlet holes beside the prop) exposed to th= e air flow.=A0 In effect this hole with little/no resistance to airflow can "pressurize" the cowl and raise the ai= r pressure behind the radiator cores reducing the pressure differential and= therefore the cooling.=A0 Exhaust augmentation is theoretically a way to r= educe the under the cowl pressure by using the exhaust pulse to "pump" air from under the cowl, thereby improvi= ng the Dp across the core and therefore your cooling.

=A0

While exhaust augmentation can apparently work - th= ere was a KITPLANE issue back several years ago on the topic showing severa= l installations where this was used.=A0 However, from what I read (and think I understand), it takes some carefully plannin= g to get an installation to work correct and the effort is not trivial.=A0 = Give the challenges you may encounter (such as motor mount struts, etc), fa= brication of the augmentation exit, =A0the need to have the exhaust pulse exit at or inside the cowl (or const= ruct an extended bottom cowl tunnel) means you would have the bark of a rot= ary in front of your feet.=A0 Also, to gain maximum advantage of these tech= niques, it is desirable to have the exhaust velocity at the maximum - which implies little/no muffling.=A0 Hav= ing had my muffler back out one time (at the cowl exit), I can tell you tha= t you do not want to position the pilot behind the exhaust outlet (in my op= inion).=A0 It is much quieter when you have the exhaust exit behind the position of the pilot {:>).

=A0

Some few people seem to have been able to achieve s= ome degree of success, but even in aircraft where you have an engine withou= t the aggressive bark of the rotary, you seldom see it used.=A0 The basic reason (in my opinion), is that it offers= few advantages (cooling wise) that can not be achieved easier and more rel= iability by other methods.=A0 For an all out racer where noise and discomfo= rt is secondary, it may have some benefit.

=A0

Having said that, it's clear that in some insta= llations it appears to work well (see KITPLANE issue), but if it were the m= agic solution, I think many more folks would be employing it - but, again, just my opinion.

=A0

Ed

=A0

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net= ] On Behalf Of George Lendic= h
Sent: Tuesday, April 27, 2= 010 9:41 PM
To: Rotary motors in aircr= aft
Subject: [FlyRotary] Re: 2= 0B RV-8 cooling results

=A0

Ed/ Tracy,

Can't say as I understand Tracy's set- up completely, other than i= t's toward the lower end of Rad sizes. I was thinking to myself how=A0I= 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 r= unning 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=A0could 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 behi= nd the Rad. This presupposes the Rads are completely enclosed for both inle= t and outlet air.

George ( down under)

75% of my cooling problems were solved with the oil cooler chang= e I did but still needed more margin for hot weather climbs. =A0 Made the d= ecision to not change or enlarge the cooling outlet (that adds drag)=A0 so went ahead and butchered the pretty inlets I= made.=A0
Ed Anderson's spreadsheet on BTUs & CFM cooling air required was in= strumental in deciding to go this way.=A0=A0 It showed that without negativ= e pressure on the back side of the rads, there would never be enough cfm to= do the job during climb at full throttle.=A0 Negative pressure is what I had when I flew without the cowl on but oh wha= t a draggy condition that was.

The old inlets were 4.5" diameter for the radiator and 4.125" dia= meter for oil cooler.
New inlets are=A0=A0=A0=A0=A0=A0=A0 5.190" for the rad,=A0 and =A0 4.8= 75" dia for the oil.

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

Results were excellent.=A0 Oil temp went down 19 degrees at the test speed = (130) and water temp dropped 9 degrees.=A0 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.=A0 Temp was around 175 at 130. =A0=A0 Oil Temp in climb remained below redline (21= 0) but the temperature lapse rate today made results not very meaningful.= =A0 OAT was dropping 14 degrees a minute at 3000 fpm climb rate.

now back to that nasty composite work to pretty up the inlets again.=A0 The= y 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&= quot;=A0 It's a term from a=A0 Sci Fi book (Vintage Season)=A0 meaning = something which induces euphoria.=A0





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