X-Virus-Scanned: clean according to Sophos on Logan.com X-SpamCatcher-Score: 80 [XXX] (41%) BODY: contains "ambien" obfuscated (21%) URL: contains host with port number (21%) URL: HTTP is broken (-19%) URL: weird port adjustment Return-Path: Received: from ms-smtp-05.southeast.rr.com ([24.25.9.104] verified) by logan.com (CommuniGate Pro SMTP 5.1.8) with ESMTP id 2047415 for flyrotary@lancaironline.net; Wed, 16 May 2007 08:32:05 -0400 Received-SPF: pass receiver=logan.com; client-ip=24.25.9.104; envelope-from=eanderson@carolina.rr.com Received: from edward2 (cpe-024-074-103-061.carolina.res.rr.com [24.74.103.61]) by ms-smtp-05.southeast.rr.com (8.13.6/8.13.6) with SMTP id l4GCVGbS027703 for ; Wed, 16 May 2007 08:31:17 -0400 (EDT) Message-ID: <001501c797b6$555eb2a0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Marginal Cooling contributes to Crash. Date: Wed, 16 May 2007 08:32:56 -0400 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3028 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.3028 X-Virus-Scanned: Symantec AntiVirus Scan Engine Ah, now you want measurements as well {:>). Have a good trip and enjoy, Al. We'll still be here when you get back. Ed ----- Original Message ----- From: "al p wick" To: "Rotary motors in aircraft" Sent: Tuesday, May 15, 2007 9:30 PM Subject: [FlyRotary] Re: Marginal Cooling contributes to Crash. > "Marginal cooling" is actually a point on a curve. So that supports your > concept of it being fuzzy, undefined. If you find yourself watching the > temperature and changing decisions based on it, you are approaching > marginal. If you have outside air temps you have to avoid, you are > clearly marginal. > There is no reason to tolerate anything approaching marginal. Ask > yourself: "Is it truly necessary that I have temp this high?" Simple > solutions can yield much better safety margin. It does not necessarily > have to include larger radiators. There are lot's of decisions made > during construction that negatively affect performance. Type of rad, > position of rad. Little air flow diverters are very effective. > > If you guys just measure your temps as I described earlier, then all of > the successes could be copied. > > Headed to beach, so I may not respond to posts for a few days. Seeking > razor clams..mmmmmmmm. > > As always, enjoyed the discussion Ed. > > > -al wick > Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam > timing. > Artificial intelligence in cockpit, N9032U 240+ hours from Portland, > Oregon > Glass panel design, Subaru install, Prop construct, Risk assessment info: > http://www.maddyhome.com/canardpages/pages/alwick/index.html > > > > > > On Tue, 15 May 2007 21:04:16 -0400 "Ed Anderson" > writes: >> >> No question, Al, that a cooling system failure can ruin your day, >> particularly if it detracts you from "Fly the Airplane" mantra. But, >> I also >> agree its a tough sell, but I believe it is a tough sell because of >> whether >> you or I, or Joe or Bill mean the same thing by a marginal system. >> Perhaps >> we could come to a meaningful definition but one eludes me at the >> moment. I >> mean consider the nature of the beast, we KNOW of some >> configurations which >> have repeatedly shown they perform their function - now, you might >> think >> that would mean everyone would adopt them - but, who am I trying to >> kid - >> certainly not you, Al? There is always going to be somebody (most >> folks in >> this activity?) who are going to want to skin that grape another >> (better?) >> way. >> >> I guess the real underlying question in my mind is how do you >> define a >> marginal system. I have flown my system for 10 years now in all >> sorts of >> Summer heat, long waits while taxing, etc. I (obviously) personally >> don't >> view the system as marginal but actually finely tuned to my >> installation. So >> while we can all perhaps agree you shouldn't fly with a marginal >> cooling >> system - I'm not as certain we could all agree on the definition of >> one >> {:>). >> >> I gather (hopefully correctly) that you feel any temperature >> excursion >> beyond some point temperature point X in some regime of flight would >> mean a >> marginal system. So the next question becomes what temperature >> point X and >> why? There should be some meaningful reason we choose temp X. Like >> beyond >> X Water boils, coolant boils, metal cracks, spark plugs shatter? >> >> For instance, I fly with no thermostat, for whatever adverse effect >> that >> might have on engine efficiency, it does one thing a system with a >> thermostat can not do. My system begins removing heat from the >> engine the >> second the engine is started, with a thermostat no (significant) >> heat is >> removed until the coolant reaches the thermostat opening temperature >> and >> only then does the cooling start becoming effective in removing >> heat. I have >> never had problems with ground operations on hot days. The system >> cools >> fine - until I pour the fuel to it on take off and then the >> temperatures >> start a slow rise - fortunately so does airspeed and airflow through >> the >> cores. Once 120IAS is reached my "marginal" period is over and >> cooling (if >> anything) is excessive at my normal cruise power settings. >> >> Yes, hotter coolant does mean more theoretically efficient cooling >> - but, >> I don't think that increase efficiency can make up for the fact my >> system >> has been removing heat from the system from start up. Now some >> folks would >> probably think that without a thermostat the system is marginal - I >> >> obviously am not one of them{:>), but, again, my point is how to we >> define >> the parameters and how do we populate those parameter with >> meaningful >> values. >> >> I suspect the generic parameters would have a degree of commonality >> for >> just about all liquid cooled engines - but the values for a Subaru >> would >> undoubtedly be different from a Rotary or from perhaps a Chevy V8. >> Just a >> gut feel there, but again how do we decide. Exhaust valve temps >> might be a >> suitable parameter for some engines but would of course be >> meaningless for >> the rotary. >> >> My point is I think it would be difficult to get agreement on the >> parameters from which to evaluate a marginal system much less agree >> on the >> parameter values that will categorize a marginal system. The >> extremes are >> easier to define >> If the engine seizes from over-heating, if the coolant boils out of >> the >> system, the fiberglass cowl catches fire, etc, we could probably >> all >> agreed that the cooling system was "marginal". But, if none of that >> (or >> similar things) happens - what makes it marginal? 1 Degree F over >> some set >> limit? 10F over? You get my point. >> >> >> Second, I think anyone who puts Evans in a marginal cooling system >> clearly >> doesn't understand the thermodynamics of the situation (in my >> opinion). >> With a lesser Cp (considerably less than water and even an >> water/anti-freeze mixture) you will remove even less heat from the >> engine >> per unit mass of coolant flow and ensure you will eventually cause >> even the >> high boiling temp Evans solution to overheat. >> >> Yes, you can heat Evans to a higher temp before it boils - but all >> that >> means is your engine and everything else is at that temp as well. I >> do >> believe there is one way you could remove more heat with Evans but >> that is >> only if you increased the flow rate of the coolant. That stuff was >> originally used for racing and racers care more about winning than >> longevity >> of the engine - so it does have its uses, I just don't believe >> aircraft >> engines is one of them And even if I am wrong about the other >> aspects of >> Evans, its higher operating temperature may be withstood by some >> engines >> but the rotary is not one of them (again in my opinion). >> >> I always enjoy the pertinent points you bring up, Al. They >> certainly force >> us (me for sure) to re-examine our premises and perhaps even change >> them. >> I guess we could say any marginal system, be it cooling, fuel, >> ignition, >> controls, structural is operating on the "edge" and it could only >> take a >> factor or two different to suddenly make the system very, very >> marginal. >> So it comes down to the inescapable fact that those of use who 1. >> Fly, 2. >> Fly experimental aircraft, 3. Fly with Alternative engines are >> probably >> closer to the margin in a larger number of areas than we would care >> to dwell >> upon - sanity might be one of them {:>). >> >> Best Regards >> >> Ed >> >> >> >> >> >> >> >> ----- Original Message ----- >> From: "al p wick" >> To: "Rotary motors in aircraft" >> Sent: Tuesday, May 15, 2007 7:01 PM >> Subject: [FlyRotary] Re: Marginal Cooling contributes to Crash. >> >> >> >I know it's a tough sell. Hard to believe you have significant risk >> when >> > you are normally able to just throttle back, wait a while, and >> temps >> > start to drop. Tons of times I heard the same response in my >> > occupation...."If he just reacts to xxx, then the problem goes >> away". >> > Marginal systems place you closer to the boil over temp. It only >> takes a >> > 20F rise in ambient temp to affect marginal system. It takes 80F >> rise to >> > affect robust system. If you heat soak a marginal system, that >> places you >> > right on the edge of boil over. Add a bubble of air to marginal >> system, >> > you are screwed. As your temps rise, your piloting skills drop off >> due to >> > anxiety. I've gotten a number of reports from guys who landed gear >> up >> > even though their warning horn was blasting away...just because >> they were >> > worried about the engine behavior. >> > >> > The incident I referred to was the guy that took off with >> marginal >> > cooling. Landed at Whyoming airport, changed to Evans, then took >> off and >> > bit it. Underlying root cause was marginal cooling. He never would >> have >> > changed to Evans if he had started out with robust system. >> > >> > Our day to day problem solving skills set us up for failure. We >> are so >> > used to making marginal decisions, that we find it difficult to >> see the >> > significance of robust design. Easy to fly for years with marginal >> > system, then all of a sudden the other contributing factors stack >> against >> > you....... >> > High ambient temp, high altitude, heat soaked engine. >> Fortunately, >> > statistically it will only nail a few guys. A few for marginal >> cooling, a >> > few for marginal fuel delivery. One common cause....sys designed >> too >> > close to failure point. >> > >> > Certainly agree, spray bar a good solution. >> > >> > -al wick >> > Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and >> cam >> > timing. >> > Artificial intelligence in cockpit, N9032U 240+ hours from >> Portland, >> > Oregon >> > Glass panel design, Subaru install, Prop construct, Risk >> assessment info: >> > http://www.maddyhome.com/canardpages/pages/alwick/index.html >> > >> > >> > On Tue, 15 May 2007 15:10:12 -0400 "Ed Anderson" >> > writes: >> >> Hi Al, >> >> >> >> I would be interested in these other factors you mention >> referring >> >> to the >> >> crash. I have years of flying under cooling deficit conditions >> >> right after >> >> take off as do others as you mention - without any problem. >> Every >> >> study I >> >> have read on cooling indicates the designer strives for an >> optimum >> >> cooling >> >> system- for an operating regime - (frequently for the cruise >> regime) >> >> and >> >> then uses whatever, cowl flaps, exhaust augmentation, spray >> bars, >> >> to cool >> >> it under less than ideal conditions- like immediately after >> take >> >> off. I >> >> understand even the P51 faced that problem on taxi and take off >> on >> >> hot days. >> >> >> >> You can certainly design your system to not have a "take off" >> >> cooling >> >> deficit but, you are now starting to talk bigger radiators (may >> have >> >> space >> >> constraints), more weight, cooling drag, etc. for some airframes >> and >> >> flight >> >> regimes a bit more would not be significant, but for other >> airframes >> >> and >> >> speeds these factors become more significant. >> >> >> >> Perhaps we need to be as bit more specific as to what degree of >> >> "overheating" we are referring to. My limit on oil temp is 200F, >> my >> >> limit >> >> on coolant is 220F and those only for the short duration of >> launch >> >> and up to >> >> 120 MPH IAS at which time my system is on the good side of >> cooling. >> >> 10 years >> >> of flying with that limitation has not yet revealed any problem >> so >> >> far as I >> >> can tell. Now with a rotary, if your temps are going 240F on >> oil >> >> and >> >> similar on coolant then I personally would feel that is too high >> and >> >> >> >> something should be done. >> >> >> >> A crash to which the overheating was apparently one of a set of >> >> factor is >> >> certainly something that I would be interested in. How bad was >> the >> >> >> >> overheating and how did it contribute to the crash? I (and I >> >> believe all of >> >> us) would be interested in the details of the crash you mention >> that >> >> was >> >> contributed to by marginal cooling - for lessons learned. A >> spray >> >> bar does >> >> indeed provide a considerable margin, Tracy flew with one for a >> bit >> >> (mainly >> >> for racing I believe), I've never experimented with one since I >> >> don't go >> >> racing and once airborne and 120 IAS and my system is happy. >> >> However, it >> >> might be interesting to see exactly how much benefit such a >> simple >> >> system >> >> would provide. >> >> >> >> Gotta put that on my long list of "to do" things. Another >> thing >> >> I have >> >> been thinking more about is that my GM cores which have served >> well >> >> are >> >> approaching the 10 year point. They are really not designed for >> >> water flow >> >> as we know, so I would not be surprised that a custom made set >> of >> >> radiator >> >> cores might lower my coolant temps by 5-10F by simply providing >> >> improved >> >> coolant flow. >> >> >> >> As always, appreciate your input and perspective, Al. Any risk >> we >> >> can >> >> eliminate or reduce is worth examining and taking action on. >> Again, >> >> would >> >> be interested in the details of the accident if you have them. >> >> >> >> Best Regards >> >> >> >> Ed >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> ----- Original Message ----- >> >> From: "al p wick" >> >> To: "Rotary motors in aircraft" >> >> Sent: Tuesday, May 15, 2007 12:08 PM >> >> Subject: [FlyRotary] Re: First Flight - Renesis in RV-7A >> >> >> >> >> >> >I know a lot of you guys are flying with conditions similar to >> what >> >> Ed >> >> > describes. It gets hot during climb, but cools off during >> cruise. >> >> It >> >> > seems manageable. I encourage you to not tolerate such a >> design. >> >> This is >> >> > a root cause for crashes. You have marginal system, normally >> >> easily >> >> > managed, but suddenly other factors come into play. We had >> crash >> >> last >> >> > year with marginal cooling as one of the root causes. >> >> > >> >> > One simple solution that provides extra safety margin is to >> just >> >> add a >> >> > spray bar in front of radiator. It just takes a tiny mist of >> water >> >> to >> >> > dramatically improve cooling. Strongly encourage spray bar at >> a >> >> minimum. >> >> > Great solution for initial testing. >> >> > >> >> > Even then, I would seek improvements that eliminate need for >> spray >> >> bar. >> >> > There are simple improvements out there. There are guys flying >> >> exact same >> >> > hp as you, yet they have 10 to 20% better cooling efficiency. >> Find >> >> out >> >> > what they are doing right. >> >> > >> >> > If you had everyone flying record their temp as they climb out >> >> from sea >> >> > level to 12k ft, you would find a couple guys with better >> >> efficiency than >> >> > the others. You'd have to record outside air temp. Coolant, >> oil >> >> temp at >> >> > start and end of climb. Everyone would have to climb at same >> rate, >> >> say 80 >> >> > mph, then 90mph. Compare area of radiators. With some facts >> like >> >> this you >> >> > could end up with some genuine breakthroughs. Speculations do >> not >> >> lead to >> >> > breakthroughs. >> >> > >> >> > >> >> > -al wick >> >> > Cozy IV powered by Turbo Subaru 3.0R with variable valve lift >> and >> >> cam >> >> > timing. >> >> > Artificial intelligence in cockpit, N9032U 240+ hours from >> >> Portland, >> >> > Oregon >> >> > Glass panel design, Subaru install, Prop construct, Risk >> >> assessment info: >> >> > http://www.maddyhome.com/canardpages/pages/alwick/index.html >> >> > >> >> > >> >> > On Tue, 15 May 2007 07:47:09 -0400 "Ed Anderson" >> >> > writes: >> >> >> Congratulations, Dennis. A great day for sure! A lot of >> work >> >> and $$ >> >> >> coming >> >> >> to successful launch. Unless you make the cooling system >> >> capacity >> >> >> considerably greater than you need at cruise, you will always >> run >> >> a >> >> >> cooling >> >> >> deficit during climb - high power, low airspeed. So long as >> it >> >> >> doesn't >> >> >> exceed your limits and cools off once sufficient airspeed is >> >> reach, >> >> >> you >> >> >> should be fine >> >> >> >> >> >> Ed >> >> >> ----- Original Message ----- >> >> >> From: "Dennis Haverlah" >> >> >> To: "Rotary motors in aircraft" >> >> >> Sent: Monday, May 14, 2007 10:23 PM >> >> >> Subject: [FlyRotary] First Flight - Renesis in RV-7A >> >> >> >> >> >> >> >> >> >I made my first flight this evening!! All systems worked >> fine >> >> - >> >> >> cooling >> >> >> >was marginal in climb but we had a good inversion and the >> >> outside >> >> >> air >> >> >> >temperature was quite warm. Several neighbors videoed the >> >> flight >> >> >> and I >> >> >> >heard several comments about how quiet the rotary plane was >> when >> >> we >> >> >> played >> >> >> >the video. We had a 180 hp RV-7A flying chase and on the >> video >> >> it >> >> >> was much >> >> >> >louder!! Only flew about 10 minutes but made an acceptable >> >> landing >> >> >> >> >> >> >considering there were about 50 people watching. I'll post >> >> some >> >> >> picures of >> >> >> >the plane later tonight. >> >> >> > >> >> >> > Dennis Haverlah >> >> >> > RV-7A, Renesis, James Cowl >> >> >> > Radiators under engine >> >> >> > Catto 76 in dia- 8 in pitch >> >> >> > EC-2, Em-2, RD1-C >> >> >> > >> >> >> > -- >> >> >> > Homepage: http://www.flyrotary.com/ >> >> >> > Archive and UnSub: >> >> >> > http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> >> >> >> >> >> >> >> -- >> >> >> Homepage: http://www.flyrotary.com/ >> >> >> Archive and UnSub: >> >> >> http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> >> >> >> >> >> >> > >> >> > >> >> > -al wick >> >> > Cozy IV powered by Turbo Subaru 3.0R with variable valve lift >> and >> >> cam >> >> > timing. >> >> > Artificial intelligence in cockpit, N9032U 240+ hours from >> >> Portland, >> >> > Oregon >> >> > Glass panel design, Subaru install, Prop construct, Risk >> >> assessment info: >> >> > http://www.maddyhome.com/canardpages/pages/alwick/index.html >> >> > >> >> > -- >> >> > Homepage: http://www.flyrotary.com/ >> >> > Archive and UnSub: >> >> > http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> >> >> >> >> -- >> >> Homepage: http://www.flyrotary.com/ >> >> Archive and UnSub: >> >> http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> >> >> >> > >> > >> > -al wick >> > Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and >> cam >> > timing. >> > Artificial intelligence in cockpit, N9032U 240+ hours from >> Portland, >> > Oregon >> > Glass panel design, Subaru install, Prop construct, Risk >> assessment info: >> > http:// >> > >> > -- >> > Homepage: http://www.flyrotary.com/ >> > Archive and UnSub: >> > http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> >> -- >> Homepage: http://www.flyrotary.com/ >> Archive and UnSub: >> http://mail.lancaironline.net:81/lists/flyrotary/List.html >> >> > > > -al wick > Cozy IV powered by Turbo Subaru 3.0R with variable valve lift and cam > timing. > Artificial intelligence in cockpit, N9032U 240+ hours from Portland, > Oregon > Glass panel design, Subaru install, Prop construct, Risk assessment info: > http://www.maddyhome.com/canardpages/pages/alwick/index.html > > -- > Homepage: http://www.flyrotary.com/ > Archive and UnSub: > http://mail.lancaironline.net:81/lists/flyrotary/List.html