X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from [64.12.137.6] (HELO imo-m25.mail.aol.com) by logan.com (CommuniGate Pro SMTP 5.2.13) with ESMTP id 3579967 for flyrotary@lancaironline.net; Mon, 13 Apr 2009 19:13:32 -0400 Received-SPF: pass receiver=logan.com; client-ip=64.12.137.6; envelope-from=WRJJRS@aol.com Received: from imo-ma03.mx.aol.com (imo-ma03.mx.aol.com [64.12.78.138]) by imo-m25.mail.aol.com (v107.10) with ESMTP id RELAYIN1-249e3c6a48b; Mon, 13 Apr 2009 19:11:32 -0400 Received: from WRJJRS@aol.com by imo-ma03.mx.aol.com (mail_out_v40_r1.5.) id q.d2b.49767c60 (37528) for ; Mon, 13 Apr 2009 19:11:06 -0400 (EDT) Received: from smtprly-db03.mx.aol.com (smtprly-db03.mx.aol.com [205.188.249.154]) by cia-mb01.mx.aol.com (v123.3) with ESMTP id MAILCIAMB011-5c3f49e3c6872c6; Mon, 13 Apr 2009 19:11:05 -0400 Received: from WEBMAIL-MA11 (webmail-ma11.webmail.aol.com [64.12.88.75]) by smtprly-db03.mx.aol.com (v123.3) with ESMTP id MAILSMTPRLYDB035-5c3f49e3c6872c6; Mon, 13 Apr 2009 19:11:03 -0400 References: To: flyrotary@lancaironline.net Subject: Re: [FlyRotary] Re: forced landings Date: Mon, 13 Apr 2009 19:11:03 -0400 X-AOL-IP: 64.12.78.138 In-Reply-To: X-MB-Message-Source: WebUI MIME-Version: 1.0 From: wrjjrs@aol.com X-MB-Message-Type: User Content-Type: multipart/alternative; boundary="--------MB_8CB8AA440426157_B28_25D_WEBMAIL-MA11.sysops.aol.com" X-Mailer: AOL Webmail 42402-STANDARD Received: from 66.253.96.220 by WEBMAIL-MA11.sysops.aol.com (64.12.88.75) with HTTP (WebMailUI); Mon, 13 Apr 2009 19:11:03 -0400 Message-Id: <8CB8AA4402F4E9F-B28-12A@WEBMAIL-MA11.sysops.aol.com> X-Spam-Flag:NO ----------MB_8CB8AA440426157_B28_25D_WEBMAIL-MA11.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Bill, The beading tools would bead .06 aluminum. You might want to heat it a bit= first to prevent cracking. Alternately you can cut a small groove which= gives some slip prevention, but admittedly not as good as a bead. Lastly= you can rough up the end and use a high temp epoxy to "rib" the end of th= e tube. Bill Jepson -----Original Message----- From: Bill Bradburry To: Rotary motors in aircraft Sent: Mon, 13 Apr 2009 2:17 pm Subject: [FlyRotary] Re: forced landings Dave=E2=80=99s number 4 below brings up a question I have been pondering. =C2=A0 How do you put a bead on the ends of aluminum tubing so the hose will not= slip off??? =C2=A0 My tubing is inch and a quarter and probably 0.060 thick.=C2=A0 Suggestion= s appreciated. =C2=A0 Thanks, Bill B =C2=A0 From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Be= half Of David Leonard Sent: Monday, April 13, 2009 4:48 PM To: Rotary motors in aircraft Subject: [FlyRotary] Re: forced landings =C2=A0 Mark, =C2=A0 Thanks for putting together this database.=C2=A0 I agree with you and Al= G.=C2=A0that we should keep it to issues with the engine and it's systems= .=C2=A0 But I also agree with John and Al W. that we should somewhere incl= ude things that probably would have caused an in-flight failure, especiall= y when found on pre-flight, run-up or take off roll.=C2=A0 That is good st= uff.=C2=A0 Not the idiot-pilot-owner stuff like forgetting to attach the= =3D2 0return fuel line, but the alternator bracket and PSRU issues etc - that= could really help someone. =C2=A0 Similarly, just because it is in flight does not make it newsworthy.=C2=A0= Like the intake hose blow offs that John and I have both experienced.=C2= =A0 Sure, something happened and you are damn sure going to return to the= airport and check it out even though you are pretty sure you know what ha= ppened and it will not affect the safety of flight.=C2=A0 OOps, didn't tig= hten that hose tight enough. =C2=A0 In other words, I think Johns incident #1 is far more significant than inc= ident #4. =C2=A0 Maybe to clarify: =C2=A0 #1 caused actual damage to the engine AND he NEEDED to land soon because= of oil loss.=C2=A0 Power produced was less than normally aspirated power.= =C2=A0 This is an interesting mechanical possibility (that a turbine blade= somehow got BACK into the engine to bust the apex seal) and something imp= ortant to consider when designing a turbo install.=C2=A0 =C2=A0 #4 caused only a reduction=C2=A0to normally aspirated power and a skipped= heart beat or two.=C2=A0 No damage, no real need to land other than as a= precaution.=C2=A0 No design flaw or mechanical issue - just an underestim= ation on how tight to make the hose clamp. (and believe me, they have to= be very=C2=A0tight if there is no bead under the hose.) -- David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net On Mon, Apr 13, 2009 at 6:16=3D2 0AM, Mark Steitle wrote: Dave, =C2=A0 I have decided to take Al's suggestion and=C2=A0limit=C2=A0the criteria fo= r the spreadsheet to basically include any in-flight system failure which= interrupts the planned flight and results in a premature landing.=C2=A0= Based on this, I will add #3 & #4 as well as the one=C2=A0resulting from= =C2=A0a ruptured coolant hose.=C2=A0 =C2=A0 Mark S. On Mon, Apr 13, 2009 at 7:55 AM, David Leonard wrote= : Mark, And did you get these?=C2=A0 Added by me and John Slade under the wr= ong thread title: On Sun, Apr 12, 2009 at 5:15 PM, John Slade wr= ote: Here's a few for the list, Mark, 1. Stock turbo bearings collapsed & took out apex seal. Flew home at reduc= ed power. =C2=A0 2. Fuel filer (sinstered bronze) looked clean but was restricting fuel flo= w. Flew home on other tank. =C2=A0 3. Bad / intermittent contact on ignition timing sensor made engine run ro= ugh. Landed normally and repaired. =C2=A0 4. Turbo hose blew off on take-off. Returned to land at reduced power. John ------=C2=A0 =C2=A0 Been there, done that. (the blown-off intake hose) =C2=A0 Also: I have burned out 2 turbos.=C2=A0 The first caused precautionary/urgent la= nding at an airport pending shutting off fuel flow to the turbo.=C2=A0 The= second, I flipped a turbo oil shut off switch and flew 1000NM to get home= . =C2=A0 Had a fuel pump die in flight, switched to the other and kept flying.(soft= fai lure) I had a bad injector enable switch causing rough running during some phase= one flying (after major change)...=C2=A0 landed normally=C2=A0 Forgot to re-connect fuel return line in engine bay after doing some work.= =C2=A0 dumped a couple gallons of fuel onto the running engine until I sme= lled gas and shut down the engine.. (never left the parking space - but it= could have been really bad. Cracked alternator mount bracket found on pre-flight during phase one test= ing.=C2=A0 Would have lost cooling and alternator if it happened now. PSRU sun gear pin broke from a backfire during run-up.=C2=A0 Was able to= taxi back but would not have been able to fly. =C2=A0 This is good - broke a coolant line in flight and smelled coolant...=C2=A0= landed at nearby airport and taxied up to restaurant with steam spewing= out of the cowl.=C2=A0 Me and my buddy calmly walked into the restaurant= and had breakfast.=C2=A0 Afterward, we borrowed some tools and fixed the= coolant line.=C2=A0 Went back into the restaurant to ask for 2 pitchers= of water to put in our plane.=C2=A0 Continued ski trip to Mammoth.=C2=A0= The end. -- David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net On Sun, Apr 12, 2009 at 2:03 PM, Mark Steitle wrote: Thanks Bill, With the addition of Bill's exciting adventure, and one of my own, we're= up to 18 incidents in the database.=C2=A0 These last two, along with Ed's= brake fire, and an oil coolant rupture,=3D2 0totals four incidents involving fires during ground operations.=C2=A0 Hop= efully, everyone carries at least one fire extinguisher in their airplane. Mark S. =C2=A0 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. =C2=A0 From=C2=A0 my post of Feb. 8 Well, I haven't heard of this happening before -- I was ground running my= engine to=C2=A0 tune it with the EM-2 and EC-2.=C2=A0 Ran for almost an= hour, at various rpm's to change the manifold pressure and tweak the sett= ings. 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. =C2=A0 Engine was running good, took it up to ~6000 rpm swinging a 76x76 Catto pr= op, when suddenly there was steam and fluid on my windshield. Shut it down= by killing power to the EC-2. Coolant everywhere. =C2=A0 Got out and looked to diagnose the problem -- NOT my plumbing.=C2=A0 A FRE= EZE PLUG in the iron housing had blown out. Rapid coolant dump. =C2=A0 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= , but corner is charred. =C2=A0 Now in rep air mode. =C2=A0 -------------------------- Update since this incident:=C2=A0 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. =C2=A0 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 =C2=A0 Charlie, That's a very good point.=C2=A0 I'm trying to stay away from assigning a= "cause" for whatever happened because I don't have all the facts.=C2=A0= I have a field that says "Explanation of Failure".=C2=A0 Hopefully, we ca= n make statements as you suggest.=C2=A0 Sometimes, even the FAA gets it wr= ong, like the time they attributed the engine failure to the builder remov= ing the oil injection pump.=C2=A0 Also, I doubt that we could all agree on= a "single cause" for each failure.=C2=A0 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.=C2=A0 What I hope to accomplish is to poi= nt out areas where we need to be more careful on how we design a particula= r part or system.=C2=A0 List is at 16 now.=C2=A0 Anyone else want to add a "dark and stormy night"= story to the list?=C2=A0 Mark =C2=A0=C2=A0 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 fa= ilure. In the case of the plastic fuel flow sensor, it's highly unlikely= that use of the plastic sensor caused the failure; it was the use of plas= tic in the wrong area without any protection. The homebuilder's knee-jerk= reaction is to say 'no plastic sensors because that one melted', even tho= ugh there are tens of thousands of the same sensor in use in boating, a mu= ch more severe environment. Kind of like the canard builder who tried to put fuel in a wing built with= fuel-soluble foam. Obviously, it failed, but only because of the wrong ap= plication of products, not the products themselves. Charlie =C2=A0 From: al wick To: Rotary motors in aircraft Sent: Sunday, April 12, 2009 10:13:00 AM Subject: [FlyRotary] Re: forced landings =C2=A0 Absolutely excellent Mark. I'd encourage you to get the year the incident= occured too. That will be your proof of reduced risk from things like thi= s newsgroup. Avoid the black and white approach: forced landing or not forced. Because= all things are shades of grey. Instead rate the severity. So it's a 10 if= the guy had to glide, it's=C2=A0a 1 if he did precautionary landing. If= you also explain what happened, then a reader can easily tell you were ob= jective in your rating. The final piece is about how many flight hours, first flights there were.= Each year there are more engines f lying, so way more likely you will hear of incident. A wild assed guess is= ok, if you just base the guess on some facts. For example, you could chec= k faa database and find 100 planes registered with rotary engine in 2005.= You can guess that equals 70 hours each. Even though it's a wild assed gu= ess, it will still be excellent predictor of change over time. Each year= you have the same "error". So your numbers WILL reflect improvement. More important than anything. If you can force your self to say: "That sam= e failure will happen to me". Particularly if you can look at "contributin= g 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=C2=A0root cause. You don't want to say:" I= have efi, can't happen to me". You want to say:" I expect heat will cause= 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 it.= Your risk isn't some new cause. It's 1 of those 10 incidents that you rat= ionalized 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 forc= ed landing? Here's what I recall from memory, so it likely is missing a few; =C2=A0 =C2=A0=C2=A0=C2=A0 3 forced landings due to ruptured oil coolers =C2=A0=C2=A0=C2=A0 1 forced landing due to apex seal coming out of its slo= t (rotor out of spec) =C2=A0=C2=A0=C2=A0 1 forced landing due to improper assembly of engine (se= al wedged between rotor & side housing) =C2=A0=C2=A0=C2=A0 1 forced landing on highway due to catastrophic overhea= ting of engine =C2=A0=C2=A0=C2=A0 2 forced landings (one fatal) due to probable fuel syst= em design flaw=C2=A0 =C2=A0=C2=A0=C2=A0 1 forced landing on highway due to ingestion of FOD.=C2= =A0 There were a few others, such as turbo failures which allowed for continue= d operation at reduced power, so we may or may not wish to include those= here.=C2=A0 While a number of these incidents date back quite a few years, and we have= made excellent progress, it says to me that we still have room for improv= ement in the peripheral department.=C2=A0 The good news is that out of all= of the incidents listed above, none of them were caused by a true engine= failure.=C2=A0 That's where the rotary has really earned my respect as a= viable 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 tolerant th= an 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 ha= ve the benefit of 70 years worth of experience flying behind the typical= LyCon farm implement I think overall our odds are considerably worse. Com= es down to how well an individual engineer's his installation and there is= a tremendous amount of variation here. =C2=A0 The dependence on electronics in the typical rotary install=C2=A0 is a goo= d example. I may be a little=C2=A0sensitive to this issue since I've been= trying to find an intermittent glitch (2 times in 22 hours of engine test= ing). =C2=A0 Mike Wills RV-4 N144MW=C2=A0=C2=A0 ----- 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 =C2=A0 Good analysis and logic, Gary. =C2=A0 You=E2=80=99d make a good addition to the =E2=80=9Crotary community=E2=80= =9D.=C2=A0 I have noticed over the 10 years I have been flying my rotary= powered RV-6A that the problems have decreased considerably, the success= rate and completion rate has gone up and first flights are now occurring without significant problems =E2=80=93 even cooling is OK {:= >).=C2=A0 I believe most of this improvement can be attributed to folks sh= aring their knowledge, problems and solutions with others - such as on thi= s list.=C2=A0 =C2=A0 I know that fewer parts count is often touted as one of the rotary benefit= =E2=80=93 and while it is true that the part count is lower, the most sig= nificant thing (in my opinion) is not only does the lower part count help= reliability (if it is not there =E2=80=93 it can not break), but if you= look a the design of the eccentric shaft (for example) you notice the abs= ence of the jogs in a typical crankshaft and their stress points.=C2=A0 Th= e thing is over 3=E2=80=9D in diameter at some points and does not have th= e same inertia loads born by a piston crankshaft.=C2=A0 The parts that are= there are of very robust design.=C2=A0 Finally, the rotary is (I believe)= more tolerant of damage and tends to fail =E2=80=9Cgradually and graceful= ly=E2=80=9D, it can take a licking and keep on ticking as the old saying= goes.=C2=A0 Only extended time and numbers will provide the true MTBF for= the rotary, but I believe it looks very promising. =C2=A0 Failure of rotary engines 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 =E2=80=93 with probably fuel the prime culprit.=C2=A0 The good= news is that for some platforms (such as the RVs) we have pretty much established what will make an installation succes= sful.=C2=A0 The Canard crowd is fast approaching that status with their so= mewhat more challenging cooling requirements being over come. =C2=A0 =C2=A0 Having lost a rotor during flight due to putting in high compressio= n rotors with worn apex seal slots worn beyond specs (found this out later= =E2=80=93 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 mix= ture knob to full rich =E2=80=93 flowing 14.5 GPH =E2=80=93 a lot of it un= doubtedly =C2=A0being blown through the disabled rotor.=C2=A0 Flew it back= 60 miles to a suitable runway and made a non-eventful landing.=C2=A0=C2= =A0 There was a small increase in vibration due to the power strokes no lo= nger being balanced, but nothing bad and you could still read the needles= on the gauges.=C2=A0 Other folks have had FOD damage to a rotor and also= make it to a safe landing.=C2=A0 Two folks lost cooling (one loss of cool= ant fluid , one lost of water pump) and while they did cook the engines,= both made it back to a safe landing.=C2=A0 So all things considered, I th= ink the rotary continues to show that if the installation is designed prop= erly, it makes a very viable and reliable aircraft power plant. =C2=A0 Failure of rotary engines in aircraft are extremely rare, but unfortunatel= y, as with many alternative engine installations, auxil iary subsystems such as fuel and ignition frequently being one-off designs= - have been the cause of most failures.=C2=A0 The good news is that for= some platforms (such as the RVs) we have pretty much established what wil= l make an installation successful.=C2=A0 The Canard crowd is fast approach= ing that status with their somewhat more challenging cooling requirements= being over come. =C2=A0 My rotary installation cost me $6500 back in 1996, the primary cost being= a rebuilt engine $2000 and the PSRU $2900.=C2=A0 I have since purchased= a 1991 turbo block engine from Japan for $900 and rebuilt it myself for= another $2200. =C2=A0My radiators (GM evaporator cores) cost $5.00 from= the junk yard and another $50.00 each for having the bungs welded on.=C2= =A0 So depending on how much you buy and how much you build the price can= vary considerably.=C2=A0 Today, I would say it would take a minimum of ar= ound $8000 and more nominally around $10000 for a complete rotary installa= tion in an RV =E2=80=93 some folks could do it for less, some for more. =C2=A0 But, regardless of the technical merit (or not) in someone=E2=80=99s mind,= the crucial thing (in my opinion) is you need to address two personal fac= tors: =C2=A0 1.=C2=A0 What is your risk tolerance?=C2=A0 It doesn=E2=80=99t really matt= er how sexy some =E2=80=9Cexotic=E2=80=9D engine installation may seem =E2= =80=93 if you are not comfortable flying behind (or in front) of it, then= it certainly does not =C2=A0makes sense to go that route.=C2=A0 After all= , this is supposed to have an element of fun and enjoyment to it. =C2=A0 2.=C2=A0 What is your knowledge, experience and background (and you don=E2= =80=99t have to be an engineer) and do you feel comfortable with the level= of involvement needed. =C2=A0 So hope you continue to contribute to expanding our knowledge and understa= nding of the rotary in its application to power plant for aircraft. =C2=A0 =C2=A0 Best Regards =C2=A0 Ed =C2=A0 =C2=A0 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 Be= half Of Gary Casey Sent: Saturday, April 11, 2009 8:36 AM To: Rotary motors in aircraft Subject: [FlyRotary] Re: Rotary Engines =C2=A0 Just to add a few more comments and answers to the several excellent comme= nts posted: =C2=A0 How many parts does it take to make a rotary rotate? =C2=A0Well, "parts ar= en't parts" in this case. =C2=A0Mark was right in that there are maybe 4= "major" components, but you have to define major. =C2=A0A piston engine= certainly has far more major parts. =C2=A0Is a valve a "major" part? =C2= =A0I think so. =C2=A0Is a rotor corner button a major part? =C2=A0Not sure= , but probably not. =C2=A0Is each planet gear in the PSRU a major part? = =C2=A0I say yes, and the PSRU is an integral part of the20rotary engine.= =C2=A0As someone correctly pointed out, it's not how many parts, but the= reliability of the total system that counts. =C2=A0Just looking at the hi= story 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 th= e concept. =C2=A0It's more to do with the experimental nature of the build= s and installations. =C2=A0My original point, perhaps not well expressed= is that to say there are just 4 parts is an oversimplification. =C2=A0But= let's face it, to put in an engine that has had many thousands of identic= al predecessors is less "experimental" than one that hasn't.. =C2=A0 Are we ES drivers more conservative? =C2=A0Probably so, since the ES is pr= obably 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. =C2=A0Therefore, it tends to attract conservative builders= and owners. =C2=A0Not surprising then that almost all ES's have tradition= al powerplants, with the most excellent exception of Mark. =C2=A0While the= re may be more, I know of only two off-airport landings caused by engine= failures in the ES in almost 20 years of experience. =C2=A0One was caused= by fuel starvation right after takeoff (fatal) and one was caused by a PS= RU failure in an auto engine conversion. =C2=A0So our old-fashioned conser= vative nature has served us pretty well. =C2=A0 Yes, I was assuming that the rotary had electronic fuel injection and ignition, but that by itself doesn't change the inherent fuel efficien= cy of the engine. =C2=A0Direct injection does have a potential to improve= BSFC because the fuel charge can be stratified. =C2=A0It will probably de= crease available power, though. =C2=A0I think the best rotary will be 5%= less efficient than the "best" piston engine(same refinements added to ea= ch). =C2=A0But I stated that as a simple disadvantage - as Mark pointed ou= t, it isn't that simple. =C2=A0The rotary already comes configured to run= on auto gas. =C2=A0The piston engine can also be so configured, but the= compression ratio reduction would reduce its BSFC and maybe durability ad= vantage. =C2=A0The total operating cost is certainly significantly less if= auto gas can always be used to refuel. =C2=A0I assumed in my assessment= that it will only be available 50% of the time. =C2=A0The real disadvanta= ge, 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. =C2=A0 Is the engine less expensive? =C2=A0I did a thorough analysis of a direct-= drive recip auto engine installation and my conclusion was that if the aut= o engine were equivalent in reliability to the aircraft engine it would li= kely cost just as much. =C2=A0Is the same true of the rotary? =C2=A0I'm no= t sure, but you have to consider the total cost, including engineering of= all the parts in the system, not just the core engine. =C2=A0I would love= to do a rotary installation, but I don't think I could justify it by cost reduction. =C2=A0 It wasn't mentioned in the posts, but some have claimed the rotary is "smo= other" than a recip. =C2=A0I at first resisted that notion. =C2=A0Sure, an= y rotary given sufficient counterbalancing, is perfectly balanced. =C2=A0A= 4-cylinder opposed recip is not - there is a significant secondary couple= . =C2=A0The 6-cylinder opposed engine is perfectly balanced, but only for= PRIMARY and SECONDARY forces and couples - higher order forces have never= really been analyzed, although they would be very small. =C2=A0And then= consider the forces within the engine that have to be resisted by that lo= ng, heavy, but flexible crankshaft. =C2=A0So it isn't the mechanical balan= ce that gives the rotary an advantage. =C2=A0Let's take a look at the the= torsional pulsations, comparing the 3-rotor against the 6-cylinder: =C2= =A0A 6-cylinder engine has 3 power impulses per rotation, as does the 3-ro= tor, so they are the same, right? =C2=A0Wrong. =C2=A0They both incorporate= 4 "stroke" cycles, meaning that there separate and sequential intake, com= pression, power and exhaust events so that is the same for both. =C2=A0The= power event, which is the source of the torque impulse,=C2=A0takes 1/2 of= a crank rotation for the recip. =C2=A0In the rotary the power event requi= res 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. =C2=A0Therefore, the torsional excitation=3D2 0delivered to the propeller, PSRU and to the airframe is significantly les= s than for a recip. =C2=A0And if you analyze the actual forces imparted,= they go down by the square of the rpm. =C2=A0The torsional vibration ampl= itude goes down by a factor of 4 just because the rpm of the rotary turns= about twice as fast. =C2=A0If you've skipped to the bottom of the paragra= ph, as you probably should have :-), yes the rotary is "smoother" - a LOT= smoother.. (my apologies to rotary purists, for simplicity I used the wor= d "crankshaft" for both engines) =C2=A0 But just because you can burn auto gas should you? =C2=A0The biggest probl= ems with auto gas in recip aircraft have nothing to do with the engine, bu= t with the high vapor pressure of the fuel - it is more prone to vapor loc= k. =C2=A0The fuel systems of certified aircraft are not particularly well= designed with regard to vapor lock. =C2=A0"Fortunately", rotary engines= typically have no mechanical fuel pump and are forced to rely on electric= pumps. =C2=A0Fortunately because the pumps can be located at the very bot= tom of the aircraft and close to the fuel tanks, making vapor lock much le= ss likely. =C2=A0I would caution any builders to consider vapor lock possi= bilities very seriously, much more so if you intend to run auto gas. =C2= =A0when I was going to do this I planned to put one electric pump in the= wing root of each wing, feeding the engine directly(the check valve in th= e non-running pump prevents back-feeding). =C2=A0Redundancy was by a "cros= sfeed" line that could connect the tanks together. =C2=A0 And thanks, Mark for - probably incorrectly - referring to me as a "good= engineer". =C2=A0I'll have to put that in my resume! =C2=A0 Have a good day, Gary (do you allow us outsiders in your events? =C2=A0I'll park well away :-) =C2=A0 __________ Information from ESET NOD32 Antivirus, version of virus signatu= re database 3267 (20080714) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com/ =C2=A0 =C2=A0 =C2=A0 -- David Leonard Turbo Rotary RV-6 N4VY http://N4VY.RotaryRoster.net http://RotaryRoster.net =C2=A0 ----------MB_8CB8AA440426157_B28_25D_WEBMAIL-MA11.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8" Bill,
The beading tools would bead .06 aluminum. You might want to heat it a bit= first to prevent cracking. Alternately you can cut a small groove which= gives some slip prevention, but admittedly not as good as a bead. Lastly= you can rough up the end and use a high temp epoxy to "rib" the end of th= e tube.
Bill Jepson


-----Original Message-----
From: Bill Bradburry <bbradburry@bellsouth.net>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Sent: Mon, 13 Apr 2009 2:17 pm
Subject: [FlyRotary] Re: forced landings

Dave=E2=80=99s numb= er 4 below brings up a question I have been pondering.
 
How do you put a be= ad on the ends of aluminum tubing so the hose will not slip off???<= /FONT>
 
My tubing is inch= and a quarter and probably 0.060 thick.  Suggestions appreciated.
 
Thanks,
Bill B
0A
 
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of David Leonard
Sent: Monday, April 13, 20= 09 4:48 PM
To: Rotary motors in aircr= aft
Subject: [FlyRotary] Re:= forced landings
 
Mark,
 
Thanks for putting together this database.  I ag= ree with you and Al G. that we should keep it to issue s with the engine and it's systems.  But I also agree with John and= Al W. that we should somewhere include things that probably would have ca= used an in-flight failure, especially when found on pre-flight, run-up or= take off roll.  That is good stuff.  Not the idiot-pilot-owner= stuff like forgetting to attach the return fuel line, but the alternator= bracket and PSRU issues etc - that could really help someone.
 
Similarly, just because it is in flight does not make= it newsworthy.  Like the intake hose blow offs that John and I have= both experienced.  Sure, something happened and you are damn sure go= ing to return to the airport and check it out even though you are pretty= sure you know what happened and it will not affect the safety of flight.&= nbsp; OOps, didn't tighten that hose tight enough.
 
In other words, I think Johns incident #1 is far more= significant than incident #4.
 < /SPAN>
Maybe to clarify:
 
#1 caused actual damage to the engine AND he NEEDED= to land soon because of oil loss.  Power produced was less than norm= ally aspirated power.  This is an interesting mechanical possibility= (that a turbine blade somehow got BACK into the engine to bust the apex= seal) and something important to consider when designing a turbo install.=  
 
#4 caused only a reduction to normally aspirated= power and a skipped heart beat or two.  No damage, no real need to= land other than as a precaution.  No design flaw or mechanical issue= - just an underestimation on how tight to make the hose clamp. (and belie= ve me, they have to be very tight if there is no bead under the hose.= )
--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.Rota= ryRoster.net
http://RotaryRoster.n= et
On Mon, Apr 13, 2009 at 6:16 AM, Mark Steitle <msteitle@gmail.com> wrote:
Dave,
 
I have decided to take Al's suggestion and limit=  the criteria for the spreadsheet to basically include any in-flight= system failure which interrupts the planned flight and results in a prema= ture landing.  Based on this, I will add #3 & #4 as well as the= one resulting from a ruptured coolant hose. =
 
Mark S.=
On Mon, Apr 13, 2009 at 7:55 AM, David Leonard <wdleonard@gmail.com> wrote:
Mark, And did you get these?  Added by me= and John Slade under the wrong thread title:

On Sun, Apr 12, 2009 at 5:15 PM, John Slade <jslade@canardaviation.com> wrote:<= /div>
Here's a few for the list, Mark,
1. Stock turbo bearings collapsed & took out apex seal. Flew home at= reduced power.
 
2. Fuel filer (sinstered bronze) looked clean but was restricting fuel flo= w. Flew home on other tank.
 
3. Bad / intermittent contact on ignition timing sensor made engine run ro= ugh. Landed normally and repaired.
 
4. Turbo hose blew off on take-off. Returned to land at reduced power.
John
------ 
 
Been there, done that. (the blown-off intake hose)
 
Also:
I have burned out 2 turbos.  The first caused pr= ecautionary/urgent landing at an airport pending shutting off fuel flow to= the turbo.  The second, I flipped a turbo oil shut off switch and fl= ew 1000NM to get home.
 
Had a fuel pump die in flight, switched to the othe= r and kept flying.(soft failure)
I had a bad injector enable switch causing rough runn= ing during some phase one flying (after major change)...  landed norm= ally 

Forgot to re-connect fuel return line in engine bay after doing some work.=   dumped a couple gallons of fuel onto the running engine until I sme= lled gas and shut down the engine.. (never left the parking space - but it= could have been really bad.

Cracked alternator mount bracket found on pre-flight during phase one test= ing.  Would have lost cooling and alternator if it happened now.

PSRU sun gear pin broke from a backfire during run-up.  Was able to= taxi back but would not have been able to fly.
 
This is good - broke a coolant line in flight and smelled coolant... = landed at nearby airport and taxied up to restaurant with steam spewing= out of the cowl.  Me and my buddy calmly walked into the restaurant= and had=3D2 0breakfast.  Afterward, we borrowed some tools and fixed the coolant= line.  Went back into the restaurant to ask for 2 pitchers of water= to put in our plane.  Continued ski trip to Mammoth.  The end.<= /SPAN>
--
David Leonard
On Sun, Apr 12, 2009 at 2:03 PM, Mark Steitle <msteitle@gmail.com> wrote:
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 leas= t one fire extinguisher in their airplane.

Mark S.
 
On Sun, Apr 12, 2009 at 2:56 PM, Bill Schertz <<= A href=3D"mailto:wschertz@comcast.net">wschertz@comcast.net> wrote:=
One other thing to watch out for -- This occu= rred during ground testing, but if it had happened in the air it would hav= e been a forced landing.
 
From  my post of Feb. 8
Well, I haven't heard of this happening befor= e -- 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 cowl= ing off to allow good exit area since I was tied down. Coolant pressure ab= out 14 psi as reported on the EM-2.
 
Engine was running good, took it up to ~600= 0 rpm swinging a 76x76 Catto prop, when suddenly there was steam and fluid= on my windshield. Shut it down by killing power to the EC-2. Coolant ever= ywhere.
 
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 suddenl= y from full tilt, either the proximity of the cowl to the exhaust, or poss= ibly some of the coolant on the exhaust started a small fire on my cowl.= Put it out with extinguisher, but 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 ha= s inspected the engine. I am currently reinstalling it and getting ready= for more tuning exercises.
 
Bill Schertz
KIS Cruiser #4045
N343BS
----- Original Message -----
From:20Mark Steitle
Sent:= Sunday, April 12, 2009 1:51 PM
Subject:<= /B> [FlyRotary] Re: forced landings
 
Charlie,

That's a very good point.  I'm trying to stay away from assigning a= "cause" for whatever happened because I don't have all the f acts.  I have a field that says "Explanation of Failure".  Hopef= ully, we can make statements as you suggest.  Sometimes, even the FAA= gets it wrong, like the time they attributed the engine failure to the bu= ilder 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 accompl= ish is to point out areas where we need to be more careful on how we desig= n a particular part or system. 

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

Mark   
On Sun, Apr 12, 2009 at 11:46 AM, Charlie England <= ;ceengland@bellsouth.net>= ; 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 unlikely that use of the plastic sensor caused the failure;= it was the use of plastic in the wrong area without any protection. The= homebuilder's knee-jerk reaction is to say 'no plastic sensors because th= at one melted', even though there are tens20of thousands of the same senso= r in use in boating, a much more severe environment.

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

Charlie
 
From: al wick <alwick@juno.com<= /A>>
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 incide= nt occured too. That will be your proof of reduced risk from things like= this newsgroup.
Avoid the black and white approach: forced landing or not forced. Becau= se all things are shades of grey. Instead rate the severity. So it's a 10= if the guy had to glide, it's a 1 if he did precautionary landing.= If you also 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 wer= e. Each year there are more engines flying, so way more likely you will he= ar of incident. A wild assed guess is ok, if you just base the guess on so= me facts. For example, you could check faa database and find 100 planes re= gistered with rotary engine in 2005. You can guess that equals 70 hours ea= ch. Even though it's a wild assed guess, it will still be excellent predic= tor of change over time. Each year you have the same "error". So your numb= ers WILL reflect improvement.
More important than anything. If you can force your self to say: "That same fai= lure will happen to me". Particularly if you can look at "contributing fac= tors". Then you can dramatically reduce personal risk. Good example: We ha= d 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 cause 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= it. 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 <msteitle@gmai= l.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: [FlyRotary] Re: Gary Casey was [FlyRotary] Re: Rota ry Engines
Date: Sun, 12 Apr 2009 06:45:24 -0500

Mike,

Has anyone ever tried to document the rotary incidents resulting in a forc= ed 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 slo= t (rotor out of spec)
    1 forced landing due to improper assembly of engine (se= al wedged between rotor & side housing)
    1 forced landing on highway due to catastrophic overhea= ting of engine
    2 forced landings (one fatal) due to probable fuel syst= em design flaw 
    1 forced landing on highway due to ingestion of FOD.&nb= sp;

There were a few others, such as turbo failures which allowed for continue= d operation at reduced power, so we may or may not wish to include those= here. 

While a number of these incidents date back quite a few years, and we have= made excellent progress, it says to me that we still have room for improv= ement 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= viable a/c engine.

Pay attention to the details!

Mark S.

On Sat, Apr 11, 2009 at 9:22 PM, Mike Wills <rv-4mike@cox.net> wrote:
This has been an interesting thread. In the= end, it doesnt really matter how many "major" parts you have - even a min= or failure can bring you down. While I believe the basic rotary engine its= elf is more fault tolerant than a recip, the peripherals used in the typic= al rotary install are a lot more complex than a typical recip install. Sin= ce we rotary fliers dont have the benefit of 70 years worth of experience= flying behind the typical LyCon farm implement I think overall our odds= are considerably worse. Comes down 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 trying to find= an intermittent glitch (2 times in 22 hours of engine testing).
 
Mike Wills<= /SPAN><= /FONT>
RV-4 N144MW=  &= nbsp;
----- Original Message -----
From: Ed Anderson
Sent:= Saturday, April 11, 2009 7:31 AM
Subject:<= /B> [FlyRotary] Gary Casey was [FlyRotary] Re: Rotary Engines=
 
Good analysis and logic, Gary.=
 
You=E2=80=99d make a good addition to= the =E2=80=9Crotary community=E2=80=9D.  I have noticed over the 10= years I have been flying my rotary powered RV-6A that the problems have= decreased considerably, the success rate and completion rate has gone up= and first flights are now occurring without significant problems =E2=80= =93 even cooling is OK {:>).  I believe most of this improvement= can be attributed to folks sharing their knowledge, problems and solution= s with others - such as on this list. 
 
I know that fewer parts count is ofte= n touted as one of the rotary benefit =E2=80=93 and while it is true that= the part count is lower, the most significant thing (in my opinion) is no= t only does the lower part count help reliability (if it is not there =E2= =80=93 it can not break), but if you look a the design of the eccentric sh= aft (for example) you notice the absence of the jogs in a typical cranksha= ft and their stress points.  The thing is over 3=E2=80=9D in diameter= at some points and does not have the same inertia loads born by a piston= crankshaft.  The parts that are there are of very robust design.&nbs= p; Finally, the rotary is (I20believe) more tolerant of damage and tends= to fail =E2=80=9Cgradually and gracefully=E2=80=9D, it can take a licking= and keep on ticking 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 extreme= ly 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 =E2=80=93 with probably fuel= the prime culprit.  The good news is that for some platforms (such= as the RVs) we have pretty much established what will make an installatio= n successful.  The Canard crowd is fast approaching that status with= their somewhat more challenging cooling requirements being over come.
 
  Having lost a rotor during fli= ght due to putting in high compression rotors with worn apex seal slots wo= rn beyond specs (found this out later =E2=80=93 my fault for not being awa= re 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 fu= el mixture knob to full rich =E2=80=93 flowing 14.5 GPH =E2=80=93 a lot of= it undoubtedly  being blown through the disabled rotor.  Flew= it back 60 miles to a suitable runway and made a non-eventful landing.&nb= sp;  There was a small increase in vibration due to the power strokes= no longer being balanced, but nothing bad and you could still read the ne= edles on the gauges.  Other folks have had FOD damage to a rotor and= also make it to a safe landing.  Two folks lost cooling (one loss of= coolant fluid , one lost of water pump) and while they did cook the engin= es, 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 in= stallations, auxiliary subsystems such as fuel and ignition frequently bei= ng one-off designs - have been the cause of most failures.  The good= news is that for some platforms (such as the RVs) we have pretty much est= ablished what will make an installation successful.  The Canard crowd= is fast approaching that status=3D2 0with their somewhat more challenging cooling requirements being over come= .
 
My rotary installation cost me $6500= back in 1996, the primary cost being a rebuilt engine $2000 and the PSRU= $2900.  I have since purchased a 1991 turbo block engine from Japan= for $900 and rebuilt it myself for another $2200.  My radiators (GM= evaporator cores) cost $5.00 from the junk yard and another $50.00 each= for having the bungs welded on.  So depending on how much you buy an= d how much you build the price can vary considerably.  Today, I would= say it would take a minimum of around $8000 and more nominally around $10= 000 for a complete rotary installation in an RV =E2=80=93 some folks could= do it for less, some for more.
 
But, regardless of the technical meri= t (or not) in someone=E2=80=99s mind, the crucial thing (in my opinion) is= you need to address two personal factors:
 
1.  ; What is your risk tolerance?  It doesn=E2=80=99t really matter how= sexy some =E2=80=9Cexotic=E2=80=9D engine installation may seem =E2=80=93= if you are not comfortable flying behind (or in front) of it, then it cer= tainly does not  makes sense to go that route.  After all, this= is supposed to have an element of fun and enjoyment to it.<= /div>
 
2.  What is your knowledge, expe= rience and background (and you don=E2=80=99t have to be an engineer) and= do you feel comfortable with the level of involvement needed.
 
So hope you continue to contribute to= expanding our knowledge and understanding of the rotary in its applicatio= n to power plant for aircraft.
 
 
Best Regards
 
Ed
 
 
Ed Anderson
Rv-6A N494BW Rotary Powered=
Matthews, NC<= /div>
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 aircr= aft
Subject: [FlyRotary] Re:= Rotary Engines
 
Just to add a few more comments and answers to the several excell= ent 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 has far more major parts.  Is a valve a "major" part? &nbs= p;I think so.  Is a rotor corner button a major part?  Not sure,= but probably not.  Is each planet gear in the PSRU a major part? &nb= sp;I say yes, and the PSRU is an integral part of the rotary engine.  = ;As someone correctly pointed out, it's not how many parts, but the reliab= ility of the total system that counts.  Just looking 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 con= cept.  It's more to do with the experimental nature of the builds and= installations.  My original point, perhaps not well expressed is tha= t to 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 pre= decessors is less "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, an= d 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 tradition= al powerplants, with the most excellent exception of Mark.  While the= re may 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 starvation right after takeoff (fatal) and one was caused by a PS= RU failure in an auto engine conversion.  So our old-fashioned conser= vative 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 efficiency= of the engine.  Direct injection does have a potential to improve BS= FC because the fuel charge can be stratified.  It will probably decre= ase 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= that 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 reduct= ion would reduce its BSFC and maybe durability advantage.  The total= operating cost is certainly significantly less if auto gas can always be= used to refuel.  I assumed in my assessment that it will only be ava= ilable 50% of the time.  The real disadvantage, which I failed to sta= te, 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 flig= hts.
 
Is the engine less expensive?  I did a thorough analysis of a dire= ct-drive recip auto engine installation and my conclusion was that if the= auto engine were equivalent in reliability to the aircraft engine it woul= d likely cost just as much.  Is the same true of the rotary?  I'= m not 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 reduction.
&n= bsp;
It wasn't mentioned in the posts, but some have claimed the rotary is= "smoother" than a recip.  I at first resisted that notion.  Sur= e, any rotary given sufficient counterbalancing, is perfectly balanced. &n= bsp;A 4-cylinder opposed recip is not - there is a significant secondary= couple.  The 6-cylinder opposed engine is perfectly balanced, but on= ly for PRIMARY and SECONDARY forces and couples - higher order forces have= never really been analyzed, although they would be very small.  And= then consider the forces within the engine that have to be resisted by th= at long, heavy, but flexible crankshaft.  So it isn't the mechanical= balance that gives the rotary an advantage.  Let's take a look at th= e the torsional pulsations, comparing the 3-rotor against the 6-cylinder:=  A 6-cylinder engine has 3 power impulses per rotation, as does the= 3-rotor, so they are the same, right?  Wrong.  They both incorp= orate 4 "stroke" cycles, meaning that there separate and sequential intake= , compression, power and exhaust events so that is the same for both. &nbs= p;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 even= t requires 1/4 of a ROTOR rotation, but the rotor rotates at 1/3 crank rot= ation - the result is that the power impulse lasts 3/4 of a CRANK rotation, 50% longer than in a recip.  Therefore, the torsion= al excitation delivered to the propeller, PSRU and to the airframe is sign= ificantly less than for a recip.  And if you analyze the actual force= s imparted, they go down by the square of the rpm.  The torsional vib= ration amplitude goes down by a factor of 4 just because the rpm of the ro= tary turns about twice as fast.  If you've skipped to the bottom of= the paragraph, as you probably should have :-), yes the rotary is "smooth= er" - 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 pr= oblems 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 with regard to vapor lock.  "Fortunately", rotary engi= nes typically have no mechanical fuel pump and are forced to rely on elect= ric pumps.  Fortunately because the pumps can be located at the very= bottom of the aircraft and close to the fuel tanks, making vapor lock muc= h less likely.  I would caution any builders to consider vapor lock= possibilities very ser iously, much more so if you intend to run auto gas.  when I was going= to do this I planned to put one electric pump in the wing root of each wi= ng, feeding the engine directly(the check valve in the non-running pump pr= events back-feeding).  Redundancy was by a "crossfeed" line that coul= d 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=3D2 0from ESET NOD32 Antivirus, version of virus signature database 3267 (2008= 0714) __________

The message was checked by ESET NOD32 Antivirus.
http= ://www.eset.com/
 
 
 



--
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.Rota= ryRoster.net
http://RotaryRoster.n= et
 


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