X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ew0-f167.google.com ([209.85.219.167] verified) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3578386 for flyrotary@lancaironline.net; Sun, 12 Apr 2009 17:04:34 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.219.167; envelope-from=msteitle@gmail.com Received: by ewy11 with SMTP id 11so2739058ewy.19 for ; Sun, 12 Apr 2009 14:03:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=RLh0zEdeDW/OC3yn0ckmOb8JKxRIrG2DcZVneVSoRB4=; b=VY/ARXgE/58jyn+bSCv/J+rM0Ucm6D52g0bWCJP34PUBqrbWllmXgBNzHz+ddHI7gp LPKRr1ONzo/DipQu6OZf8CX4h2qiIcnBLEdvJ1mzSG1FT7XdMlLcHs1u4UUxL+d36nKB rFrC1eAyAPCeYZ+XOiob+Ls4SVPaqptyz32dc= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=ksYv9BTd6wHzKXEH8vUl1KmVGwYMzunyesTkfMvUf0dz9B5x4bbRpnC3wV9r6BYNeY 8tFKQqEMLXGT1o3o3s62+bHIsARz5//pJ1ZrYioSm9m8/qLxnEPIOIa/Ms9u5MQm67t7 m3s8DJq7bhKhsItbAoW+K9CNHu/OXWSxV1gcI= MIME-Version: 1.0 Received: by 10.210.35.5 with SMTP id i5mr1225363ebi.52.1239570238964; Sun, 12 Apr 2009 14:03:58 -0700 (PDT) In-Reply-To: References: Date: Sun, 12 Apr 2009 16:03:58 -0500 Message-ID: <5cf132c0904121403i6c51173bsa59d4d9fee58ab5e@mail.gmail.com> Subject: Re: [FlyRotary] Re: forced landings From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015174c3770c48425046761efb8 --0015174c3770c48425046761efb8 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Thanks Bill, With the addition of Bill's exciting adventure, and one of my own, we're up to 18 incidents in the database. These last two, along with Ed's brake fire, and an oil coolant rupture, totals four incidents involving fires during ground operations. Hopefully, everyone carries at least one fire extinguisher in their airplane. Mark S. On Sun, Apr 12, 2009 at 2:56 PM, Bill Schertz wrote: > One other thing to watch out for -- This occurred during ground testing, > but if it had happened in the air it would have been a forced landing. > > From my post of Feb. 8 > Well, I haven't heard of this happening before -- I was ground running my > engine to tune it with the EM-2 and EC-2. Ran for almost an hour, at > various rpm's to change the manifold pressure and tweak the settings. > Cooling working well, I had the top cowling off to allow good exit area > since I was tied down. Coolant pressure about 14 psi as reported on the > EM-2. > > Engine was running good, took it up to ~6000 rpm swinging a 76x76 Catto > prop, when suddenly there was steam and fluid on my windshield. Shut it d= own > by killing power to the EC-2. Coolant everywhere. > > Got out and looked to diagnose the problem -- NOT my plumbing. A FREEZE > PLUG in the iron housing had blown out. Rapid coolant dump. > > Secondary effect -- Since I shut down suddenly from full tilt, either the > proximity of the cowl to the exhaust, or possibly some of the coolant on = the > exhaust started a small fire on my cowl. Put it out with extinguisher, bu= t > corner is charred. > > Now in repair mode. > > -------------------------- > Update since this incident: All freeze plugs (7) on the engine have been > replaced by Bruce Turrentine, and he has inspected the engine. I am > currently reinstalling it and getting ready for more tuning exercises. > > Bill Schertz > KIS Cruiser #4045 > N343BS > > ----- Original Message ----- > *From:* Mark Steitle > *To:* Rotary motors in aircraft > *Sent:* Sunday, April 12, 2009 1:51 PM > *Subject:* [FlyRotary] Re: forced landings > > Charlie, > > That's a very good point. I'm trying to stay away from assigning a "caus= e" > for whatever happened because I don't have all the facts. I have a field > that says "Explanation of Failure". Hopefully, we can make statements as > you suggest. Sometimes, even the FAA gets it wrong, like the time they > attributed the engine failure to the builder removing the oil injection > pump. Also, I doubt that we could all agree on a "single cause" for each > failure. Maybe it is due to a poor weld, or wrong choice of material, or > improper strain relief, or lack of heat shielding, or a little of each. > What I hope to accomplish is to point out areas where we need to be more > careful on how we design a particular part or system. > > List is at 16 now. Anyone else want to add a "dark and stormy night" sto= ry > to the list? > > Mark > > On Sun, Apr 12, 2009 at 11:46 AM, Charlie England > wrote: > >> I think that it's just as important to understand the real cause of the >> failure. In the case of the plastic fuel flow sensor, it's highly unlike= ly >> that use of the plastic sensor caused the failure; it was the use of pla= stic >> in the wrong area without any protection. The homebuilder's knee-jerk >> reaction is to say 'no plastic sensors because that one melted', even th= ough >> there are tens of thousands of the same sensor in use in boating, a much >> more severe environment. >> >> Kind of like the canard builder who tried to put fuel in a wing built wi= th >> fuel-soluble foam. Obviously, it failed, but only because of the wrong >> application of products, not the products themselves. >> >> Charlie >> >> ------------------------------ >> *From:* al wick >> *To:* Rotary motors in aircraft >> *Sent:* Sunday, April 12, 2009 10:13:00 AM >> *Subject:* [FlyRotary] Re: forced landings >> >> Absolutely excellent Mark. I'd encourage you to get the year the inciden= t >> occured too. That will be your proof of reduced risk from things like th= is >> newsgroup. >> >> Avoid the black and white approach: forced landing or not forced. Becaus= e >> all things are shades of grey. Instead rate the severity. So it's a 10 i= f >> the guy had to glide, it's a 1 if he did precautionary landing. If you a= lso >> explain what happened, then a reader can easily tell you were objective = in >> your rating. >> >> The final piece is about how many flight hours, first flights there were= . >> Each year there are more engines flying, so way more likely you will hea= r of >> incident. A wild assed guess is ok, if you just base the guess on some >> facts. For example, you could check faa database and find 100 planes >> registered with rotary engine in 2005. You can guess that equals 70 hour= s >> each. Even though it's a wild assed guess, it will still be excellent >> predictor of change over time. Each year you have the same "error". So y= our >> numbers WILL reflect improvement. >> >> More important than anything. If you can force your self to say: "That >> same failure will happen to me". Particularly if you can look at >> "contributing factors". Then you can dramatically reduce personal risk. = Good >> example: We had that guy that installed plastic fuel flow sensor in fuel >> line. It melted, he died. Tracy just reported hot exhaust caused fuel to >> boil out of carb. These have the same root cause. You don't want to say:= " I >> have efi, can't happen to me". You want to say:" I expect heat will caus= e a >> failure. I'll put a thin ss shield here, with a bit of fibrefax glued to >> back. So if muffler fails, it won't affect....." >> >> Every forced landing had 10 little incidents in the past that preceded i= t. >> Your risk isn't some new cause. It's 1 of those 10 incidents that you >> rationalized away, instead of saying:" that will happen to me too." >> >> Good stuff. >> >> >> -al wick >> Cozy IV with 3.0 liter Subaru >> 230+ hrs tt from Portland, Oregon >> >> ---------- Original Message ---------- >> From: Mark Steitle >> To: "Rotary motors in aircraft" >> Subject: [FlyRotary] Re: Gary Casey was [FlyRotary] Re: Rotary Engines >> Date: Sun, 12 Apr 2009 06:45:24 -0500 >> >> Mike, >> >> Has anyone ever tried to document the rotary incidents resulting in a >> forced landing? >> >> Here's what I recall from memory, so it likely is missing a few; >> >> 3 forced landings due to ruptured oil coolers >> 1 forced landing due to apex seal coming out of its slot (rotor out = of >> spec) >> 1 forced landing due to improper assembly of engine (seal wedged >> between rotor & side housing) >> 1 forced landing on highway due to catastrophic overheating of engin= e >> 2 forced landings (one fatal) due to probable fuel system design fla= w >> >> 1 forced landing on highway due to ingestion of FOD. >> >> There were a few others, such as turbo failures which allowed for >> continued operation at reduced power, so we may or may not wish to inclu= de >> those here. >> >> While a number of these incidents date back quite a few years, and we ha= ve >> made excellent progress, it says to me that we still have room for >> improvement in the peripheral department. The good news is that out of = all >> of the incidents listed above, none of them were caused by a true engine >> failure. That's where the rotary has really earned my respect as a viab= le >> a/c engine. >> >> Pay attention to the details! >> >> Mark S. >> >> >> On Sat, Apr 11, 2009 at 9:22 PM, Mike Wills wrote: >> >>> This has been an interesting thread. In the end, it doesnt really >>> matter how many "major" parts you have - even a minor failure can bring= you >>> down. While I believe the basic rotary engine itself is more fault tole= rant >>> than a recip, the peripherals used in the typical rotary install are a = lot >>> more complex than a typical recip install. Since we rotary fliers dont = have >>> the benefit of 70 years worth of experience flying behind the typical L= yCon >>> farm implement I think overall our odds are considerably worse. Comes d= own >>> to how well an individual engineer's his installation and there is a >>> tremendous amount of variation here. >>> >>> The dependence on electronics in the typical rotary install is a good >>> example. I may be a little sensitive to this issue since I've been tryi= ng to >>> find an intermittent glitch (2 times in 22 hours of engine testing). >>> >>> Mike Wills >>> RV-4 N144MW >>> >>> ----- Original Message ----- >>> *From:* Ed Anderson >>> *To:* Rotary motors in aircraft >>> *Sent:* Saturday, April 11, 2009 7:31 AM >>> *Subject:* [FlyRotary] Gary Casey was [FlyRotary] Re: Rotary Engines >>> >>> Good analysis and logic, Gary. >>> >>> >>> >>> You=92d make a good addition to the =93rotary community=94. I have not= iced >>> over the 10 years I have been flying my rotary powered RV-6A that the >>> problems have decreased considerably, the success rate and completion r= ate >>> has gone up and first flights are now occurring without significant pro= blems >>> =96 even cooling is OK {:>). I believe most of this improvement can be >>> attributed to folks sharing their knowledge, problems and solutions wit= h >>> others - such as on this list. >>> >>> >>> >>> I know that fewer parts count is often touted as one of the rotary >>> benefit =96 and while it is true that the part count is lower, the most >>> significant thing (in my opinion) is not only does the lower part count= help >>> reliability (if it is not there =96 it can not break), but if you look = a the >>> design of the eccentric shaft (for example) you notice the absence of t= he >>> jogs in a typical crankshaft and their stress points. The thing is ove= r 3=94 >>> in diameter at some points and does not have the same inertia loads bor= n by >>> a piston crankshaft. The parts that are there are of very robust desig= n. >>> Finally, the rotary is (I believe) more tolerant of damage and tends to= fail >>> =93gradually and gracefully=94, it can take a licking and keep on ticki= ng as the >>> old saying goes. Only extended time and numbers will provide the true = MTBF >>> for the rotary, but I believe it looks very promising. >>> >>> >>> >>> Failure of rotary engines are extremely rare, but unfortunately, as wit= h >>> many alternative engine installations, auxiliary subsystems such as fue= l and >>> ignition frequently being one-off designs have been the cause of most >>> failures =96 with probably fuel the prime culprit. The good news is th= at for >>> some platforms (such as the RVs) we have pretty much established what w= ill >>> make an installation successful. The Canard crowd is fast approaching = that >>> status with their somewhat more challenging cooling requirements being = over >>> come. >>> >>> >>> >>> Having lost a rotor during flight due to putting in high compression >>> rotors with worn apex seal slots worn beyond specs (found this out late= r =96 >>> my fault for not being aware of this spec limit and checking it) which = led >>> to apex seal failure and consequence lost of most of the power from one >>> rotor, I was still able to maintain 6500 MSL at WOT and fuel mixture kn= ob to >>> full rich =96 flowing 14.5 GPH =96 a lot of it undoubtedly being blown= through >>> the disabled rotor. Flew it back 60 miles to a suitable runway and mad= e a >>> non-eventful landing. There was a small increase in vibration due to = the >>> power strokes no longer being balanced, but nothing bad and you could s= till >>> read the needles on the gauges. Other folks have had FOD damage to a r= otor >>> and also make it to a safe landing. Two folks lost cooling (one loss o= f >>> coolant fluid , one lost of water pump) and while they did cook the eng= ines, >>> both made it back to a safe landing. So all things considered, I think= the >>> rotary continues to show that if the installation is designed properly,= it >>> makes a very viable and reliable aircraft power plant. >>> >>> >>> >>> Failure of rotary engines in aircraft are extremely rare, but >>> unfortunately, as with many alternative engine installations, auxiliary >>> subsystems such as fuel and ignition frequently being one-off designs -= have >>> been the cause of most failures. The good news is that for some platfo= rms >>> (such as the RVs) we have pretty much established what will make an >>> installation successful. The Canard crowd is fast approaching that sta= tus >>> with their somewhat more challenging cooling requirements being over co= me. >>> >>> >>> >>> My rotary installation cost me $6500 back in 1996, the primary cost bei= ng >>> a rebuilt engine $2000 and the PSRU $2900. I have since purchased a 19= 91 >>> turbo block engine from Japan for $900 and rebuilt it myself for anothe= r >>> $2200. My radiators (GM evaporator cores) cost $5.00 from the junk yar= d and >>> another $50.00 each for having the bungs welded on. So depending on ho= w >>> much you buy and how much you build the price can vary considerably. T= oday, >>> I would say it would take a minimum of around $8000 and more nominally >>> around $10000 for a complete rotary installation in an RV =96 some folk= s could >>> do it for less, some for more. >>> >>> >>> >>> But, regardless of the technical merit (or not) in someone=92s mind, th= e >>> crucial thing (in my opinion) is you need to address two personal facto= rs: >>> >>> >>> >>> 1. What is your risk tolerance? It doesn=92t really matter how sexy s= ome >>> =93exotic=94 engine installation may seem =96 if you are not comfortabl= e flying >>> behind (or in front) of it, then it certainly does not makes sense to = go >>> that route. After all, this is supposed to have an element of fun and >>> enjoyment to it. >>> >>> >>> >>> 2. What is your knowledge, experience and background (and you don=92t = have >>> to be an engineer) and do you feel comfortable with the level of involv= ement >>> needed. >>> >>> >>> >>> So hope you continue to contribute to expanding our knowledge and >>> understanding of the rotary in its application to power plant for aircr= aft. >>> >>> >>> >>> >>> >>> Best Regards >>> >>> >>> >>> 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 *Gary Casey >>> *Sent:* Saturday, April 11, 2009 8:36 AM >>> *To:* Rotary motors in aircraft >>> *Subject:* [FlyRotary] Re: Rotary Engines >>> >>> >>> >>> Just to add a few more comments and answers to the several excellent >>> comments posted: >>> >>> >>> >>> How many parts does it take to make a rotary rotate? Well, "parts aren= 't >>> parts" in this case. Mark was right in that there are maybe 4 "major" >>> components, but you have to define major. A piston engine certainly ha= s far >>> more major parts. Is a valve a "major" part? I think so. Is a rotor >>> corner button a major part? Not sure, but probably not. Is each plane= t >>> gear in the PSRU a major part? I say yes, and the PSRU is an integral = part >>> of the rotary engine. As someone correctly pointed out, it's not how m= any >>> parts, but the reliability of the total system that counts. Just looki= ng at >>> the history of the rotary (which, from the implication of another post)= it's >>> not that good, but I don't think it has anything to do with reliability= of >>> the concept. It's more to do with the experimental nature of the build= s and >>> installations. My original point, perhaps not well expressed is that t= o say >>> there are just 4 parts is an oversimplification. But let's face it, to= put >>> in an engine that has had many thousands of identical predecessors is l= ess >>> "experimental" than one that hasn't.. >>> >>> >>> >>> Are we ES drivers more conservative? Probably so, since the ES is >>> probably one of the experimentals most similar to production aircraft, = and >>> not just because the Columbia (can't force myself to say Cezzna :-) was= a >>> derivative. Therefore, it tends to attract conservative builders and >>> owners. Not surprising then that almost all ES's have traditional >>> powerplants, with the most excellent exception of Mark. While there ma= y be >>> more, I know of only two off-airport landings caused by engine failures= in >>> the ES in almost 20 years of experience. One was caused by fuel starva= tion >>> right after takeoff (fatal) and one was caused by a PSRU failure in an = auto >>> engine conversion. So our old-fashioned conservative nature has served= us >>> pretty well. >>> >>> >>> >>> Yes, I was assuming that the rotary had electronic fuel injection and >>> ignition, but that by itself doesn't change the inherent fuel efficienc= y of >>> the engine. Direct injection does have a potential to improve BSFC bec= ause >>> the fuel charge can be stratified. It will probably decrease available >>> power, though. I think the best rotary will be 5% less efficient than = the >>> "best" piston engine(same refinements added to each). But I stated tha= t as >>> a simple disadvantage - as Mark pointed out, it isn't that simple. The >>> rotary already comes configured to run on auto gas. The piston engine = can >>> also be so configured, but the compression ratio reduction would reduce= its >>> BSFC and maybe durability advantage. The total operating cost is certa= inly >>> significantly less if auto gas can always be used to refuel. I assumed= in >>> my assessment that it will only be available 50% of the time. The real >>> disadvantage, which I failed to state, is that the extra fuel required = for a >>> given mission might be 5 or 10% higher and that negated the weight >>> advantage, if only for long-range flights. >>> >>> >>> >>> Is the engine less expensive? I did a thorough analysis of a >>> direct-drive recip auto engine installation and my conclusion was that = if >>> the auto engine were equivalent in reliability to the aircraft engine i= t >>> would likely cost just as much. Is the same true of the rotary? I'm n= ot >>> sure, but you have to consider the total cost, including engineering of= all >>> the parts in the system, not just the core engine. I would love to do = a >>> rotary installation, but I don't think I could justify it by cost reduc= tion. >>> >>> >>> >>> It wasn't mentioned in the posts, but some have claimed the rotary is >>> "smoother" than a recip. I at first resisted that notion. Sure, any r= otary >>> given sufficient counterbalancing, is perfectly balanced. A 4-cylinder >>> opposed recip is not - there is a significant secondary couple. The >>> 6-cylinder opposed engine is perfectly balanced, but only for PRIMARY a= nd >>> SECONDARY forces and couples - higher order forces have never really be= en >>> analyzed, although they would be very small. And then consider the for= ces >>> within the engine that have to be resisted by that long, heavy, but fle= xible >>> crankshaft. So it isn't the mechanical balance that gives the rotary a= n >>> advantage. Let's take a look at the the torsional pulsations, comparin= g the >>> 3-rotor against the 6-cylinder: A 6-cylinder engine has 3 power impuls= es >>> per rotation, as does the 3-rotor, so they are the same, right? Wrong. >>> They both incorporate 4 "stroke" cycles, meaning that there separate a= nd >>> sequential intake, compression, power and exhaust events so that is the= same >>> for both. The power event, which is the source of the torque impulse, = takes >>> 1/2 of a crank rotation for the recip. In the rotary the power event >>> requires 1/4 of a ROTOR rotation, but the rotor rotates at 1/3 crank >>> rotation - the result is that the power impulse lasts 3/4 of a CRANK >>> rotation, 50% longer than in a recip. Therefore, the torsional excitat= ion >>> delivered to the propeller, PSRU and to the airframe is significantly l= ess >>> than for a recip. And if you analyze the actual forces imparted, they = go >>> down by the square of the rpm. The torsional vibration amplitude goes = down >>> by a factor of 4 just because the rpm of the rotary turns about twice a= s >>> fast. If you've skipped to the bottom of the paragraph, as you probabl= y >>> should have :-), yes the rotary is "smoother" - a LOT smoother.. (my >>> apologies to rotary purists, for simplicity I used the word "crankshaft= " for >>> both engines) >>> >>> >>> >>> But just because you can burn auto gas should you? The biggest problem= s >>> with auto gas in recip aircraft have nothing to do with the engine, but= with >>> the high vapor pressure of the fuel - it is more prone to vapor lock. = The >>> fuel systems of certified aircraft are not particularly well designed w= ith >>> regard to vapor lock. "Fortunately", rotary engines typically have no >>> mechanical fuel pump and are forced to rely on electric pumps. Fortuna= tely >>> because the pumps can be located at the very bottom of the aircraft and >>> close to the fuel tanks, making vapor lock much less likely. I would >>> caution any builders to consider vapor lock possibilities very seriousl= y, >>> much more so if you intend to run auto gas. when I was going to do thi= s I >>> planned to put one electric pump in the wing root of each wing, feeding= the >>> engine directly(the check valve in the non-running pump prevents >>> back-feeding). Redundancy was by a "crossfeed" line that could connect= the >>> tanks together. >>> >>> >>> >>> And thanks, Mark for - probably incorrectly - referring to me as a "goo= d >>> engineer". I'll have to put that in my resume! >>> >>> >>> >>> Have a good day, >>> >>> Gary >>> >>> (do you allow us outsiders in your events? I'll park well away :-) >>> >>> >>> >>> >>> >>> >>> __________ Information from ESET NOD32 Antivirus, version of virus >>> signature database 3267 (20080714) __________ >>> >>> The message was checked by ESET NOD32 Antivirus. >>> >>> http://www.eset.com/ >>> >>> >> > --0015174c3770c48425046761efb8 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Thanks Bill,

With the addition of Bill's exciting adventure, an= d one of my own, we're up to 18 incidents in the database.=A0 These las= t two, along with Ed's brake fire, and an oil coolant rupture, totals f= our incidents involving fires during ground operations.=A0 Hopefully, every= one carries at least one fire extinguisher in their airplane.

Mark S.

On Sun, Apr 12, 2009 at 2:56= PM, Bill Schertz <wschertz@comcast.net> wrote:
One other thing to watch out for -- Th= is occurred=20 during ground testing, but if it had happened in the air it would have been= a=20 forced landing.
=A0
From=A0 my post of Feb. 8
Well, I haven't heard of this happ= ening before -- I=20 was ground running my engine to=A0 tune it with the EM-2 and EC-2.=A0 Ran= =20 for almost an hour, at various rpm's to change the manifold pressure an= d tweak=20 the settings. Cooling working well, I had the top cowling off to allow good= exit=20 area since I was tied down. Coolant pressure about 14 psi as reported on th= e=20 EM-2.
=A0
Engine was running good, took it up to= ~6000 rpm=20 swinging a 76x76 Catto prop, when suddenly there was steam and fluid on my= =20 windshield. Shut it down by killing power to the EC-2. Coolant=20 everywhere.
=A0
Got out and looked to diagnose the pro= blem -- NOT=20 my plumbing.=A0 A FREEZE PLUG in the iron housing had blown out. Rapid=20 coolant dump.
=A0
Secondary effect -- Since I shut down = suddenly from=20 full tilt, either the proximity of the cowl to the exhaust, or possibly som= e of=20 the coolant on the exhaust started a small fire on my cowl. Put it out with= =20 extinguisher, but corner is charred.
=A0
Now in repair mode.
=A0
--------------------------
Update since this incident:=A0 All fre= eze plugs=20 (7) on the engine have been replaced by Bruce Turrentine, and he has inspec= ted=20 the engine. I am currently reinstalling it and getting ready for more tunin= g=20 exercises.
=A0
Bill Schertz
KIS Cruiser #4045
N343BS
----- Original Message -----
From:=20 Mark Steitle=20
Sent: Sunday, April 12, 2009 1:51=20 PM
Subject: [FlyRotary] Re: forced=20 landings

Charlie,

That's a very good point.=A0 I'm t= rying to=20 stay away from assigning a "cause" for whatever happened becaus= e I don't have=20 all the facts.=A0 I have a field that says "Explanation of Failure&q= uot;.=A0=20 Hopefully, we can make statements as you suggest.=A0 Sometimes, even the= =20 FAA gets it wrong, like the time they attributed the engine failure to th= e=20 builder removing the oil injection pump.=A0 Also, I doubt that we could a= ll=20 agree on a "single cause" for each failure.=A0 Maybe it is due = to a poor=20 weld, or wrong choice of material, or improper strain relief, or lack of = heat=20 shielding, or a little of each.=A0 What I hope to accomplish is to point= =20 out areas where we need to be more careful on how we design a particular = part=20 or system.=A0

List is at 16 now.=A0 Anyone else want to add a=20 "dark and stormy night" story to the list?=A0

Mark =A0= =A0=20

On Sun, Apr 12, 2009 at 11:46 AM, Charlie Engl= and <ceengland@bellsouth.net>=20 wrote:
I think that it's just as important to understand the real cau= se of the=20 failure. In the case of the plastic fuel flow sensor, it's highly u= nlikely=20 that use of the plastic sensor caused the failure; it was the use of pl= astic=20 in the wrong area without any protection. The homebuilder's knee-je= rk=20 reaction is to say 'no plastic sensors because that one melted'= , even though=20 there are tens of thousands of the same sensor in use in boating, a muc= h=20 more severe environment.

Kind of like the canard builder who tri= ed to=20 put fuel in a wing built with fuel-soluble foam. Obviously, it failed, = but=20 only because of the wrong application of products, not the products=20 themselves.

Charlie

From: al wick <alwick@juno.com>

To: Rotary=20 motors in aircraft <flyrotary@lancaironline.net>
Sent: Sunday, April 12, 2009 10:13:00= =20 AM
Subject: [FlyRot= ary] Re:=20 forced landings

Absolutely excellent Mark. I'd encourage you to get the year the= incident=20 occured too. That will be your proof of reduced risk from things like t= his=20 newsgroup.

Avoid the black and white approach: forced landing or not forced. Be= cause=20 all things are shades of grey. Instead rate the severity. So it's a= 10 if=20 the guy had to glide, it's=A0a 1 if he did precautionary landing. I= f you=20 also explain what happened, then a reader can easily tell you were obje= ctive=20 in your rating.

The final piece is about how many flight hours, first flights there = were.=20 Each year there are more engines flying, so way more likely you will he= ar of=20 incident. A wild assed guess is ok, if you just base the guess on some= =20 facts. For example, you could check faa database and find 100 planes=20 registered with rotary engine in 2005. You can guess that equals 70 hou= rs=20 each. Even though it's a wild assed guess, it will still be excelle= nt=20 predictor of change over time. Each year you have the same "error&= quot;. So your=20 numbers WILL reflect improvement.

More important than anything. If you can force your self to say: &qu= ot;That=20 same failure will happen to me". Particularly if you can look at= =20 "contributing factors". Then you can dramatically reduce pers= onal risk. Good=20 example: We had that guy that installed plastic fuel flow sensor in fue= l=20 line. It melted, he died. Tracy just reported hot exhaust caused fuel t= o=20 boil out of carb. These have the same=A0root cause. You don't want = to=20 say:" I have efi, can't happen to me". You want to say:&q= uot; I expect heat will=20 cause a failure. I'll put a thin ss shield here, with a bit of fibr= efax=20 glued to back. So if muffler fails, it won't affect....."

Every forced landing had 10 little incidents in the past that preced= ed=20 it. Your risk isn't some new cause. It's 1 of those 10 incident= s that you=20 rationalized away, instead of saying:" that will happen to me too.= "

Good stuff.


-al wick
Cozy IV with 3.0 liter Subaru
230+ hrs tt from=20 Portland, Oregon

---------- Original Message ----------
From:= Mark=20 Steitle <mst= eitle@gmail.com>
To: "Rotary motors in aircraft"=20 <fl= yrotary@lancaironline.net>
Subject: [FlyRotary]=20 Re: Gary Casey was [FlyRotary] Re: Rotary Engines
Date: Sun, 12 Apr = 2009=20 06:45:24 -0500

Mike,

Has anyone ever tried to document t= he=20 rotary incidents resulting in a forced landing?

Here's what = I recall=20 from memory, so it likely is missing a few;
=A0
=A0=A0=A0=20 3 forced landings due to ruptured oil coolers
=A0=A0=A0 1=20 forced landing due to apex seal coming out of its slot (rotor out of=20 spec)
=A0=A0=A0 1 forced landing due to improper assembly of=20 engine (seal wedged between rotor & side housing)
=A0=A0=A0=20 1 forced landing on highway due to catastrophic overheating of=20 engine
=A0=A0=A0 2 forced landings (one fatal) due to probable=20 fuel system design flaw=A0
=A0=A0=A0 1 forced landing on=20 highway due to ingestion of FOD.=A0

There were a few others, su= ch=20 as turbo failures which allowed for continued operation at reduced powe= r, so=20 we may or may not wish to include those here.=A0

While a number= =20 of these incidents date back quite a few years, and we have made excell= ent=20 progress, it says to me that we still have room for improvement in the= =20 peripheral department.=A0 The good news is that out of all of the=20 incidents listed above, none of them were caused by a true engine=20 failure.=A0 That's where the rotary has really earned my respect as= a=20 viable a/c engine.

Pay attention to the details!

Mark S.= =20


On Sat, Apr 11, 2009 at 9:22 PM, Mike Wills <= rv-4= mike@cox.net> wrote:
This has been an interesting thr= ead. In the=20 end, it doesnt really matter how many "major" parts you hav= e - even a=20 minor failure can bring you down. While I believe the basic rotary en= gine=20 itself is more fault tolerant than a recip, the peripherals used in t= he=20 typical rotary install are a lot more complex than a typical recip=20 install. Since we rotary fliers dont have the benefit of 70 years wor= th of=20 experience flying behind the typical LyCon farm implement I think ove= rall=20 our odds are considerably worse. Comes down to how well an individual= =20 engineer's his installation and there is a tremendous amount of v= ariation=20 here.
=A0
The dependence on electronics in= the typical=20 rotary install=A0 is a good example. I may be a little=A0sensitive=20 to this issue since I've been trying to find an intermittent glit= ch (2=20 times in 22 hours of engine testing).
=A0
Mike Wills
RV-4=20 N144MW=A0=A0
-----=20 Original Message -----
From:=20 Ed=20 Anderson
Sent:=20 Saturday, April 11, 2009 7:31 AM
Subject:=20 [FlyRotary] Gary Casey was [FlyRotary] Re: Rotary Engines

Good analysis=20 and logic, Gary.

=A0

You=92d make a=20 good addition to the =93rotary community=94.=A0 I have noticed over= the=20 10 years I have been flying my rotary powered RV-6A that the proble= ms=20 have decreased considerably, the success rate and completion rate h= as=20 gone up and first flights are now occurring without significant pro= blems=20 =96 even cooling is OK {:>).=A0 I believe most of this improveme= nt=20 can be attributed to folks sharing their knowledge, problems and=20 solutions with others - such as on this list.=A0

=A0

I know that=20 fewer parts count is often touted as one of the rotary benefit =96 = and=20 while it is true that the part count is lower, the most significant= =20 thing (in my opinion) is not only does the lower part count help=20 reliability (if it is not there =96 it can not break), but if you l= ook a=20 the design of the eccentric shaft (for example) you notice the abse= nce=20 of the jogs in a typical crankshaft and their stress points.=A0 The= =20 thing is over 3=94 in diameter at some points and does not have the= same=20 inertia loads born by a piston crankshaft.=A0 The parts that are=20 there are of very robust design.=A0 Finally, the rotary is (I=20 believe) more tolerant of damage and tends to fail =93gradually and= =20 gracefully=94, it can take a licking and keep on ticking as the old= saying=20 goes.=A0 Only extended time and numbers will provide the true MTBF= =20 for the rotary, but I believe it looks very promising.

=A0

Failure of=20 rotary engines are extremely rare, but unfortunately, as with many= =20 alternative engine installations, auxiliary subsystems such as fuel= and=20 ignition frequently being one-off designs have been the cause of mo= st=20 failures =96 with probably fuel the prime culprit.=A0 The good news= is=20 that for some platforms (such as the RVs) we have pretty much=20 established what will make an installation successful.=A0 The Canar= d=20 crowd is fast approaching that status with their somewhat more=20 challenging cooling requirements being over come.

=A0

=A0 Having=20 lost a rotor during flight due to putting in high compression rotor= s=20 with worn apex seal slots worn beyond specs (found this out later = =96 my=20 fault for not being aware of this spec limit and checking it) which= led=20 to apex seal failure and consequence lost of most of the power from= one=20 rotor, I was still able to maintain 6500 MSL at WOT and fuel mixtur= e=20 knob to full rich =96 flowing 14.5 GPH =96 a lot of it undoubtedly= =20 =A0being blown through the disabled rotor.=A0 Flew it back 60=20 miles to a suitable runway and made a non-eventful landing.=A0=A0= =20 There was a small increase in vibration due to the power strokes no= =20 longer being balanced, but nothing bad and you could still read the= =20 needles on the gauges.=A0 Other folks have had FOD damage to a roto= r=20 and also make it to a safe landing.=A0 Two folks lost cooling (one= =20 loss of coolant fluid , one lost of water pump) and while they did = cook=20 the engines, both made it back to a safe landing.=A0 So all things= =20 considered, I think the rotary continues to show that if the=20 installation is designed properly, it makes a very viable and relia= ble=20 aircraft power plant.

=A0

Failure of=20 rotary engines in aircraft are extremely rare, but unfortunately, a= s=20 with many alternative engine installations, auxiliary subsystems su= ch as=20 fuel and ignition frequently being one-off designs - have been the = cause=20 of most failures.=A0 The good news is that for some platforms (such= =20 as the RVs) we have pretty much established what will make an=20 installation successful.=A0 The Canard crowd is fast approaching th= at=20 status with their somewhat more challenging cooling requirements be= ing=20 over come.

=A0

My rotary=20 installation cost me $6500 back in 1996, the primary cost being a= =20 rebuilt engine $2000 and the PSRU $2900.=A0 I have since purchased = a=20 1991 turbo block engine from Japan for $900 and rebuilt it myself f= or=20 another $2200. =A0My radiators (GM evaporator cores) cost $5.00 fro= m=20 the junk yard and another $50.00 each for having the bungs welded= =20 on.=A0 So depending on how much you buy and how much you build the= =20 price can vary considerably.=A0 Today, I would say it would take a= =20 minimum of around $8000 and more nominally around $10000 for a comp= lete=20 rotary installation in an RV =96 some folks could do it for less, s= ome for=20 more.

=A0

But, regardless=20 of the technical merit (or not) in someone=92s mind, the crucial th= ing (in=20 my opinion) is you need to address two personal=20 factors:

=A0

1.=A0 What=20 is your risk tolerance?=A0 It doesn=92t really matter how sexy some= =20 =93exotic=94 engine installation may seem =96 if you are not comfor= table=20 flying behind (or in front) of it, then it certainly does not=20 =A0makes sense to go that route.=A0 After all, this is supposed to= =20 have an element of fun and enjoyment to it.

=A0

2.=A0 What=20 is your knowledge, experience and background (and you don=92t have = to be=20 an engineer) and do you feel comfortable with the level of involvem= ent=20 needed.

=A0

So hope you=20 continue to contribute to expanding our knowledge and understanding= of=20 the rotary in its application to power plant for=20 aircraft.

=A0

=A0

Best=20 Regards

=A0

Ed

=A0

=A0

From:=20 Rotary motors in aircraft [mailto:flyrotary@lancaironline.ne= t] On Behalf Of Gary C= asey
Sent: Saturday, April 11, = 2009 8:36=20 AM
To: Rotary m= otors in=20 aircraft
Subject:=20 [FlyRotary] Re: Rotary Engines

=A0

Just to add a few more comments and answers to=20 the several excellent comments posted:

=A0

How=20 many parts does it take to make a rotary rotate? =A0Well, "par= ts=20 aren't parts" in this case. =A0Mark was right in that ther= e are maybe=20 4 "major" components, but you have to define major. =A0A = piston=20 engine certainly has far more major parts. =A0Is a valve a "ma= jor"=20 part? =A0I think so. =A0Is a rotor corner button a major part?=20 =A0Not sure, but probably not. =A0Is each planet gear in the PSRU= =20 a major part? =A0I say yes, and the PSRU is an integral part of the= =20 rotary engine. =A0As someone correctly pointed out, it's not ho= w many=20 parts, but the reliability of the total system that counts. =A0Just= =20 looking at the history of the rotary (which, from the implication o= f=20 another post) it's not that good, but I don't think it has = anything to=20 do with reliability of the concept. =A0It's more to do with the= =20 experimental nature of the builds and installations. =A0My original= =20 point, perhaps not well expressed is that to say there are just 4 p= arts=20 is an oversimplification. =A0But let's face it, to put in an en= gine=20 that has had many thousands of identical predecessors is less=20 "experimental" than one that hasn't..

=A0

Are=20 we ES drivers more conservative? =A0Probably so, since the ES is=20 probably one of the experimentals most similar to production aircra= ft,=20 and not just because the Columbia (can't force myself to say Ce= zzna :-)=20 was a derivative. =A0Therefore, it tends to attract conservative=20 builders and owners. =A0Not surprising then that almost all ES'= s have=20 traditional powerplants, with the most excellent exception of Mark.= =20 =A0While there may be more, I know of only two off-airport landings= =20 caused by engine failures in the ES in almost 20 years of experienc= e.=20 =A0One was caused by fuel starvation right after takeoff (fatal) an= d=20 one was caused by a PSRU failure in an auto engine conversion. =A0S= o=20 our old-fashioned conservative nature has served us pretty=20 well.

=A0

Yes, I was assuming that the rotary had=20 electronic fuel injection and ignition, but that by itself doesn= 9;t=20 change the inherent fuel efficiency of the engine. =A0Direct=20 injection does have a potential to improve BSFC because the fuel ch= arge=20 can be stratified. =A0It will probably decrease available power,=20 though. =A0I think the best rotary will be 5% less efficient than t= he=20 "best" piston engine(same refinements added to each). =A0= But I stated=20 that as a simple disadvantage - as Mark pointed out, it isn't t= hat=20 simple. =A0The rotary already comes configured to run on auto gas.= =20 =A0The piston engine can also be so configured, but the compression= =20 ratio reduction would reduce its BSFC and maybe durability advantag= e.=20 =A0The total operating cost is certainly significantly less if auto= =20 gas can always be used to refuel. =A0I assumed in my assessment tha= t=20 it will only be available 50% of the time. =A0The real disadvantage= ,=20 which I failed to state, is that the extra fuel required for a give= n=20 mission might be 5 or 10% higher and that negated the weight advant= age,=20 if only for long-range flights.

=A0

Is=20 the engine less expensive? =A0I did a thorough analysis of a=20 direct-drive recip auto engine installation and my conclusion was t= hat=20 if the auto engine were equivalent in reliability to the aircraft e= ngine=20 it would likely cost just as much. =A0Is the same true of the rotar= y?=20 =A0I'm not sure, but you have to consider the total cost, inclu= ding=20 engineering of all the parts in the system, not just the core engin= e.=20 =A0I would love to do a rotary installation, but I don't think = I=20 could justify it by cost reduction.

=A0

It=20 wasn't mentioned in the posts, but some have claimed the rotary= is=20 "smoother" than a recip. =A0I at first resisted that noti= on.=20 =A0Sure, any rotary given sufficient counterbalancing, is perfectly= =20 balanced. =A0A 4-cylinder opposed recip is not - there is a=20 significant secondary couple. =A0The 6-cylinder opposed engine is= =20 perfectly balanced, but only for PRIMARY and SECONDARY forces and= =20 couples - higher order forces have never really been analyzed, alth= ough=20 they would be very small. =A0And then consider the forces within th= e=20 engine that have to be resisted by that long, heavy, but flexible= =20 crankshaft. =A0So it isn't the mechanical balance that gives th= e=20 rotary an advantage. =A0Let's take a look at the the torsional= =20 pulsations, comparing the 3-rotor against the 6-cylinder: =A0A=20 6-cylinder engine has 3 power impulses per rotation, as does the=20 3-rotor, so they are the same, right? =A0Wrong. =A0They both=20 incorporate 4 "stroke" cycles, meaning that there separat= e and=20 sequential intake, compression, power and exhaust events so that is= the=20 same for both. =A0The power event, which is the source of the torqu= e=20 impulse,=A0takes 1/2 of a crank rotation for the recip. =A0In the= =20 rotary the power event requires 1/4 of a ROTOR rotation, but the ro= tor=20 rotates at 1/3 crank rotation - the result is that the power impuls= e=20 lasts 3/4 of a CRANK rotation, 50% longer than in a recip.=20 =A0Therefore, the torsional excitation delivered to the propeller,= =20 PSRU and to the airframe is significantly less than for a recip.=20 =A0And if you analyze the actual forces imparted, they go down by t= he=20 square of the rpm. =A0The torsional vibration amplitude goes down b= y=20 a factor of 4 just because the rpm of the rotary turns about twice = as=20 fast. =A0If you've skipped to the bottom of the paragraph, as y= ou=20 probably should have :-), yes the rotary is "smoother" - = a LOT=20 smoother.. (my apologies to rotary purists, for simplicity I used t= he=20 word "crankshaft" for both engines)

=A0

But=20 just because you can burn auto gas should you? =A0The biggest=20 problems with auto gas in recip aircraft have nothing to do with th= e=20 engine, but with the high vapor pressure of the fuel - it is more p= rone=20 to vapor lock. =A0The fuel systems of certified aircraft are not=20 particularly well designed with regard to vapor lock.=20 =A0"Fortunately", rotary engines typically have no mechan= ical fuel=20 pump and are forced to rely on electric pumps. =A0Fortunately becau= se=20 the pumps can be located at the very bottom of the aircraft and clo= se to=20 the fuel tanks, making vapor lock much less likely. =A0I would=20 caution any builders to consider vapor lock possibilities very=20 seriously, much more so if you intend to run auto gas. =A0when I wa= s=20 going to do this I planned to put one electric pump in the wing roo= t of=20 each wing, feeding the engine directly(the check valve in the=20 non-running pump prevents back-feeding). =A0Redundancy was by a=20 "crossfeed" line that could connect the tanks=20 together.

=A0

And=20 thanks, Mark for - probably incorrectly - referring to me as a &quo= t;good=20 engineer". =A0I'll have to put that in my=20 resume!

=A0

Have a good day,

Gary

(do=20 you allow us outsiders in your events? =A0I'll park well away= =20 :-)

=A0




__________ Information from ESET NOD32=20 Antivirus, version of virus signature database 3267 (20080714)=20 __________

The message was checked by ESET NOD32=20 Antivirus.

http://www.eset.com/

=


--0015174c3770c48425046761efb8--