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 3578309 for flyrotary@lancaironline.net; Sun, 12 Apr 2009 14:21:33 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.219.167; envelope-from=msteitle@gmail.com Received: by ewy11 with SMTP id 11so2685678ewy.19 for ; Sun, 12 Apr 2009 11:20:53 -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=kXiT0JH0WqzZx38XkTYAkX9KtS2HhfXyJQ6J5YHyz4I=; b=P4wMvfJ0SsJYcShBFj8oBGq11uME4bYGHCFiQRFR8PGJ8gCc5lgRoKsZdeskz4UKw8 68U4Hs0UXEBJxCoMCMNSCy14Ezo3cJ+TZHw8GWWP4A9ttOefTV4bLGWeZmum8Ozfb2wy UngBAPmMu3R26BC6MjqHOM2H5AqwghLYHQ4OE= 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=eVIKbJsMn+B7xKUdRU9U0KVSRaUlub6cvNythdVNVngbmACsEDSXJxYt6x96w3lRVC ByCNbQPv0PslMsFQn+K8LTkEAFzeTN0BpBy3tivc3RGh5B2RWNz4bbH/MCCPLFy7dH/I EE5Qeb9K/7KTl4SE2lkzdFYsKV2Zv4H/Gz2WQ= MIME-Version: 1.0 Received: by 10.210.115.17 with SMTP id n17mr2517923ebc.19.1239560453450; Sun, 12 Apr 2009 11:20:53 -0700 (PDT) In-Reply-To: References: Date: Sun, 12 Apr 2009 13:20:53 -0500 Message-ID: <5cf132c0904121120m392cbbc3v572a0487ea8824da@mail.gmail.com> Subject: Re: [FlyRotary] Engine Events was [FlyRotary] Re: Rotary Engines From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015174c40a4816f6504675fa875 --0015174c40a4816f6504675fa875 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Ed, Aren't you forgetting the incident involving the missing woodruff key in th= e oil pump? As I recall, another aborted takeoff (good decision). Mark On Sun, Apr 12, 2009 at 11:58 AM, Ed Anderson wr= ote: > Ok, Mark > > > > I think I see one (or more) of my =93events=94 in your list. However, no= ne > actually required a forced landing =96 in other words, I could have remai= ned > airborne should I have choose to do so. In fact, I did - until a suitabl= e > and safe landing site was reached. Well, Ok, the lost rotor really did b= eg > for a landing as soon as safely feasible {:>) > > > > Event 1: > > I lost the apex seal in my worn high compression rotors at 160 hours on t= he > block from a complete rebuild of a Japanese imported 1991 turbo core. > > > > Probably most important decision during the incident was: > > 1. Immediately turn for closest good air field when the engine started > to act abnormal > 2. Recognizing that the EGT on rotor 1 going to minimum indicated lack > of useful combustion in that rotor > 3. Realizing that power (or lack thereof) was going to be an issue, I > reached over and turned up the manual fuel mixture to maximum rich =96= that > move the fuel flow from 7 gph up to over 14 gph. Needless to say a lo= t of > expensive fuel was not providing much power on the bad rotor. But, I > managed to maintain 6400 MSL fully loaded with fuel and camping gear. > 4. After landing, I found it took much more throttle to taxi up hill o= n > one rotor. > > > > > > After loosing the rotor on way to 2005 Sun & Fun I landed at what turned > out to be a derelict airport (FB0) had just left and radios were being > stolen from aircraft on the field. A county investigator informed me aft= er > checking me out because I was =93disassembling=94 my aircraft to get the = engine > off to take home to repair. > > > > Event 2: > > > > Because (in part) of my concern for my aircraft on said airfield, I haste= n > (too hastily it turns out) rebuild my engine with new rotors. I had the > engine buttoned up and turned it over =96 it was indeed a bit harder to t= urn > over than I recalled from previous rebuilds =96 but there was no scraping > sound and compression was good, so convinced myself just a damn good tigh= t > rebuild! So reinstalled the engine. Even after it was running, I noted > that for the first hour - anytime I reduced the rpm below 2000 rpm the > engine would quite. (Did I fail to mention that I had plenty of warning > from the engine as well as from Bruce Turentine and Tracy Crook). But, > after the engine had =93loosened up=94 a bit, it ran fine. > > > > One the way to Charlie England=92s Mississippi Rotary fly in later that > spring, I noticed my coolant pressure was very slowly increasing =96 like > about 1 psi each hour of flight. It started out at around 10-12 and by = the > time I got to Charlie=92s place it was up to 18 psi. Well, I pretty much= knew > that I had a leak between coolant galleys and combustion chamber. Flew o= n > to Louisiana to visit Kin folks, upon departing one week later, I got up = to > just about lift-off speed but the engine was missing a bit. Nothing > serious, power was good, but still=85.. I aborted the take off. Had brak= e > line failure, hydraulic fluid fire and went off the runway into a ditch > (fortunately slow speed and shallow ditch). Thanks to Laura and Tracy Cr= ook > was able to rebuild the engine (without haste this time) during which tim= e I > found that one of the small triangular end pieces of apex seals was missi= ng > from the front rotor, instead there were two silver dollar size blue spot= s > on the iron side housings (that was also the vicinity where the TES O rin= gs > had failed (due to the clear localized high temps). Apparently the apex > part fell into one of the milled lightening holes in the side of the roto= r =96 > if it had not fallen into the hole which provided just enough clearance f= or > the engine to rotate =96 I am certain I would not have been able to rotat= e the > assembly by hand or starter. > > > > So in this case, no forced landing =96 never got airborne. Then there wa= s > the 12 mile engine-out glide =96 but that had nothing to do with the engi= ne > and everything to do with the pilot, so I won=92t go there {:>) > > > > So here is some meat for your project {:>) > > > > > > 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] *O= n > Behalf Of *Mark Steitle > *Sent:* Sunday, April 12, 2009 7:45 AM > *To:* Rotary motors in aircraft > *Subject:* [FlyRotary] Re: Gary Casey was [FlyRotary] Re: Rotary Engines > > > > 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 o= f > 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 engine > 2 forced landings (one fatal) due to probable fuel system design flaw > 1 forced landing on highway due to ingestion of FOD. > > There were a few others, such as turbo failures which allowed for continu= ed > 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 hav= e > 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 a= ll > 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 viabl= e > 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 tha= n 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 th= e > benefit of 70 years worth of experience flying behind the typical LyCon f= arm > 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 > > 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 notic= ed 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 gon= e > up and first flights are now occurring without significant problems =96 e= ven > cooling is OK {:>). I believe most of this improvement can be attributed= to > folks sharing their knowledge, problems and solutions with others - such = as > on this list. > > > > I know that fewer parts count is often touted as one of the rotary benefi= t > =96 and while it is true that the part count is lower, the most significa= nt > thing (in my opinion) is not only does the lower part count help reliabil= ity > (if it is not there =96 it can not break), but if you look a the design o= f the > eccentric shaft (for example) you notice the absence of the jogs in a > typical crankshaft and their stress points. The thing is over 3=94 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. > Finally, the rotary is (I believe) more tolerant of damage and tends to f= ail > =93gradually and gracefully=94, it can take a licking and keep on ticking= as the > old saying goes. Only extended time and numbers will provide the true MT= BF > for the rotary, but I believe it looks very promising. > > > > 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 =96 with probably fuel the prime culprit. The good news is that= for > some platforms (such as the RVs) we have pretty much established what wil= l > make an installation successful. The Canard crowd is fast approaching th= at > status with their somewhat more challenging cooling requirements being ov= er > 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 later = =96 > my fault for not being aware of this spec limit and checking it) which le= d > 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 knob= to > full rich =96 flowing 14.5 GPH =96 a lot of it undoubtedly being blown t= hrough > the disabled rotor. Flew it back 60 miles to a suitable runway and made = a > non-eventful landing. There was a small increase in vibration due to th= e > power strokes no longer being balanced, but nothing bad and you could sti= ll > read the needles on the gauges. Other folks have had FOD damage to a rot= or > 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 t= he > rotary continues to show that if the installation is designed properly, i= t > 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 - h= ave > been the cause of most failures. The good news is that for some platform= s > (such as the RVs) we have pretty much established what will make an > installation successful. The Canard crowd is fast approaching that statu= s > with 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 and how much you build the price can vary considerably. Tod= ay, > 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 folks = could > do it for less, some for more. > > > > But, regardless of the technical merit (or not) in someone=92s mind, the > crucial thing (in my opinion) is you need to address two personal factors= : > > > > 1. What is your risk tolerance? It doesn=92t really matter how sexy som= e > =93exotic=94 engine installation may seem =96 if you are not comfortable = 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 ha= ve > to be an engineer) and do you feel comfortable with the level of involvem= ent > needed. > > > > So hope you continue to contribute to expanding our knowledge and > understanding of the rotary in its application to power plant for aircraf= t. > > > > > > 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] *O= n > 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 has = 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 planet > gear in the PSRU a major part? I say yes, and the PSRU is an integral pa= rt > of the rotary engine. As someone correctly pointed out, it's not how man= y > parts, but the reliability of the total system that counts. Just looking= at > the history of the rotary (which, from the implication of another post) i= t's > not that good, but I don't think it has anything to do with reliability o= f > the concept. It's more to do with the experimental nature of the builds = and > installations. My original point, perhaps not well expressed is that to = say > there are just 4 parts is an oversimplification. But let's face it, to p= ut > in an engine that has had many thousands of identical predecessors is les= s > "experimental" than one that hasn't.. > > > > Are we ES drivers more conservative? Probably so, since the ES is probab= ly > one of the experimentals most similar to production aircraft, and not jus= t > because the Columbia (can't force myself to say Cezzna :-) was a derivati= ve. > Therefore, it tends to attract conservative builders and owners. Not > surprising then that almost all ES's have traditional powerplants, with t= he > most excellent exception of Mark. While there may be more, I know of onl= y > 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 takeo= ff > (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 efficiency = of > the engine. Direct injection does have a potential to improve BSFC becau= se > the fuel charge can be stratified. It will probably decrease available > power, though. I think the best rotary will be 5% less efficient than th= e > "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 ca= n > also be so configured, but the compression ratio reduction would reduce i= ts > BSFC and maybe durability advantage. The total operating cost is certain= ly > significantly less if auto gas can always be used to refuel. I assumed i= n > 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 fo= r 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-driv= e > recip auto engine installation and my conclusion was that if the auto eng= ine > were equivalent in reliability to the aircraft engine it would likely cos= t > just as much. Is the same true of the rotary? I'm not sure, but you hav= e > 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 installati= on, > but I don't think I could justify it by cost reduction. > > > > 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 rot= ary > 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 and > SECONDARY forces and couples - higher order forces have never really been > analyzed, although they would be very small. And then consider the force= s > within the engine that have to be resisted by that long, heavy, but flexi= ble > crankshaft. So it isn't the mechanical balance that gives the rotary an > advantage. Let's take a look at the 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 incorporate 4 "stroke" cycles, meaning that there separate and > sequential intake, compression, power and exhaust events so that is the s= ame > for both. The power event, which is the source of the torque impulse, ta= kes > 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 excitatio= n > delivered to the propeller, PSRU and to the airframe is significantly les= s > 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 do= wn > by a factor of 4 just because the rpm of the rotary turns about twice as > fast. If you've skipped to the bottom of the paragraph, as you probably > 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 problems > with auto gas in recip aircraft have nothing to do with the engine, but w= ith > the high vapor pressure of the fuel - it is more prone to vapor lock. Th= e > fuel systems of certified aircraft are not particularly well designed wit= h > regard to vapor lock. "Fortunately", rotary engines typically have no > mechanical fuel pump and are forced to rely on electric pumps. Fortunate= ly > 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 seriously, > 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 wing, feeding t= he > engine directly(the check valve in the non-running pump prevents > back-feeding). Redundancy was by a "crossfeed" line that could connect t= he > tanks together. > > > > And thanks, Mark for - probably incorrectly - referring to me as a "good > 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 > > > --0015174c40a4816f6504675fa875 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Ed,

Aren't you forgetting the incident involving the missing wo= odruff key in the oil pump?=A0 As I recall, another aborted takeoff (good d= ecision).=A0

Mark

On Sun, Apr 12,= 2009 at 11:58 AM, Ed Anderson <eanderson@carolina.rr.com> wrote:

Ok, Mark

=A0

I think I see one (or more) of my = =93events=94 in your list.=A0 However, none actually required a forced landing =96 in ot= her words, I could have remained airborne should I have choose to do so.=A0 In fact, I= did - until a suitable and safe landing site was reached.=A0 Well, Ok, the lost r= otor really did beg for a landing as soon as safely feasible {:>)

=A0

Event 1:

I lost the apex seal in my worn hi= gh compression rotors at 160 hours on the block from a complete rebuild of a Japanese imported 1991 turbo core.

=A0

Probably most important decision d= uring the incident was:

  1. = Immediately turn for closest good air field when the engine started to act abnorma= l
  2. = Recognizing that the EGT on rotor 1 going to minimum indicated lack of useful combustion in that rotor
  3. = Realizing that power (or lack thereof) was going to be an issue, I reached over = and turned up the manual fuel mixture to maximum rich =96 that move the fu= el flow from 7 gph up to over 14 gph.=A0 Needless to say a lot of expensi= ve fuel was not providing much power on the bad rotor.=A0 But, I managed = to maintain 6400 MSL fully loaded with fuel and camping gear.
  4. = After landing, I found it took much more throttle to taxi up hill on one rot= or.

=A0

=A0

After loosing the rotor on way to = 2005 Sun & Fun I landed at what turned out to be a derelict airport (FB0) had ju= st left and radios were being stolen from aircraft on the field.=A0 A county investigator informed me after checking me out because I was =93disassembli= ng=94 my aircraft to get the engine off to take home to repair.

=A0

Event 2:

=A0

Because (in part) of my concern fo= r my aircraft on said airfield, I hasten (too hastily it turns out) rebuild my engine with new rotors.=A0 I had the engine buttoned up and turned it over = =96 it was indeed a bit harder to turn over than I recalled from previous rebuilds =96= but there was no scraping sound and compression was good, so convinced myself just a = damn good tight rebuild!=A0 So reinstalled the engine.=A0 Even after it was runn= ing, I noted that for the first hour - anytime I reduced the rpm below 2000 rpm th= e engine would quite.=A0 (Did I fail to mention that I had plenty of warning = from the engine as well as from Bruce Turentine and Tracy Crook).=A0 But, after = the engine had =93loosened up=94 a bit, it ran fine.

=A0

One the way to Charlie England=92s Mississippi Rotary fly in later that spring, I noticed my coolant pressure = was very slowly increasing =96 like about 1 =A0psi each hour of flight.=A0 It s= tarted out at around 10-12 and by the time I got to Charlie=92s place it was up to 18 = psi.=A0 Well, I pretty much knew that I had a leak between coolant galleys and combustion chamber.=A0 Flew on to Louisiana to visit Kin folks, upon depart= ing one week later, I got up to just about lift-off speed but the engine was missing a bit.=A0 Nothing serious, power was good, but still=85.. I aborted= the take off.=A0 Had brake line failure, hydraulic fluid fire and went off the = runway into a ditch (fortunately slow speed and shallow ditch).=A0 Thanks to Laura= and Tracy Crook was able to rebuild the engine (without haste this time) during which time I found that one of the small triangular end pieces of apex seal= s was missing from the front rotor, instead there were two silver dollar size blue spots on the iron side housings (that was also the vicinity where the = TES O rings had failed (due to the clear localized high temps).=A0 Apparently t= he apex part fell into one of the milled lightening holes in the side of the r= otor =96 if it had not fallen into the hole which provided just enough clearance= for the engine to rotate =96 I am certain I would not have been able to rotate = the assembly by hand or starter.=A0

=A0

So in this case, no forced landing= =96 never got airborne.=A0 Then there was the 12 mile engine-out glide =96 but that h= ad nothing to do with the engine and everything to do with the pilot, so I won= =92t go there {:>)

=A0

So here is some meat for your proj= ect {:>)

=A0

=A0

From: Ro= tary motors in aircraft [mailto:fl= yrotary@lancaironline.net] On Behalf Of Mark Steitle
Sent: Sunday, April 12, 20= 09 7:45 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: G= ary Casey was [FlyRotary] Re: Rotary Engines

=A0

Mike,

Has anyone ever tried to document the rotary incidents resulting in a force= d landing?

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

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 include those here.=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 improvement i= n the peripheral department.=A0 The good news is that out of all of the incidents listed above, none of them were caused by a true engine failure.=A0 That's where the rotary has really earned my respect as a v= iable 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 minor fail= ure can bring you down. While I believe the basic rotary engine itself is more fault tolerant than a recip, the peripherals used in the typical rotary ins= tall 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 typ= ical 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.

=A0

The dependence on electronics in the typical rotary install=A0 is a good example. I may be a little=A0sensitive to this issue since I've been trying to find an intermittent glitch (2 times in 22 ho= urs of engine testing).

=A0

Mike Wills= <= /span>

RV-4 N144MW= =A0=A0

----- Original Message -----

<= span style=3D"font-size: 10pt; font-family: Arial; font-weight: bold;">From= : Ed Anderson

Sent: Saturd= ay, April 11, 2009 7:31 AM

Subject: [Fl= yRotary] Gary Casey was [FlyRotary] Re: Rotary Engines

=A0

Good analysis and logic, Gary.

=A0

You=92d make a good addition to th= e =93rotary community=94.=A0 I have noticed over the 10 years I have been flying my rotary powered RV-6A t= hat the problems have decreased considerably, the success rate and completion r= ate has gone up and first flights are now occurring without significant problem= s =96 even cooling is OK {:>).=A0 I believe most of this improvement can be attributed to folks sharing their knowledge, problems and solutions with ot= hers - such as on this list.=A0

=A0

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

=A0

Failure of rotary engines are extr= emely 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 =96 with probably fuel the prime culprit.=A0 The good news is that for some platforms (such as the RVs) we have pretty much established what will make an installation successful.=A0 The Canard crowd is fast approaching that status with their somewhat more challenging coolin= g requirements being over come.

=A0

=A0 Having lost a rotor during fli= ght due to putting in high compression rotors with worn apex seal slots worn beyond specs (found = this out later =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 fr= om 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 =A0being blow= n through the disabled rotor.=A0 Flew it back 60 miles to a suitable runway and made a non-eventful landing.=A0=A0 There was a small increase in vibration due to the power strokes no longer being balanced, but nothing ba= d and you could still read the needles on the gauges.=A0 Other folks have had FOD damage to a rotor and also make it to a safe landing.=A0 Two folks lost cooling (one loss of coolant fluid , one lost of water pump) and while they= did cook the engines, both made it back to a safe landing.=A0 So all things considered, I think the rotary continues to show that if the installation i= s designed properly, it makes a very viable and reliable aircraft power plant= .

=A0

Failure of rotary engines in aircr= aft are extremely rare, but unfortunately, as with many alternative engine installations, auxiliary subsystems such as fuel and ignition frequently being one-off designs - hav= e been the cause of most failures.=A0 The good news is that for some platform= s (such as the RVs) we have pretty much established what will make an installation successful.=A0 The Canard crowd is fast approaching that statu= s with their somewhat more challenging cooling requirements being over come.<= /span>

=A0

My rotary installation cost me $65= 00 back in 1996, the primary cost being a rebuilt engine $2000 and the PSRU $2900.=A0 I have since purchased a 1991 turbo block engine from Japan for $900 and rebuilt i= t myself for another $2200. =A0My radiators (GM evaporator cores) cost $5.00 from the junk yard and another $50.00 each for having the bungs welded on.=A0 So depending on how much you buy and how much you build the price ca= n vary considerably.=A0 Today, I would say it would take a minimum of around $8000 and more nominally around $10000 for a complete rotary installation i= n an RV =96 some folks could do it for less, some for more.

=A0

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

=A0

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

=A0

2.=A0 What is your knowledge, expe= rience and background (and you don=92t have to be an engineer) and do you feel comfortable with t= he level of involvement needed.

=A0

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

=A0

=A0

Best Regards

=A0

Ed

=A0

=A0

From: Ro= tary 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: R= otary Engines

=A0

Just to add a few more comments and answers to the several excellent comments poste= d:

=A0

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

=A0

Are we ES drivers more conservative? =A0Probably 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. =A0Therefore, it tends to attract conservative builders and owners. =A0Not surprising then that almos= t all ES's have traditional powerplants, with the most excellent exceptio= n of Mark. =A0While there may be more, I know of only two off-airport landings caused by engine failures in the ES in almost 20 years of experience. =A0On= e was caused by fuel starvation right after takeoff (fatal) and one was cause= d by a PSRU failure in an auto engine conversion. =A0So our old-fashioned conser= vative nature has served us pretty well.

=A0

Yes, I was assuming that the rotary had electronic fuel injection and ignition, bu= t that by itself doesn't change the inherent fuel efficiency of the engin= e. =A0Direct injection does have a potential to improve BSFC because the fuel charge can be stratified. =A0It will probably decrease available power, though. =A0I think the best rotary will be 5% less efficient than the "best" piston engine(same refinements added to each). =A0But I stated that as a simple disadvantage - as Mark pointed out, it isn't th= at simple. =A0The rotary already comes configured to run on auto gas. =A0The piston engine can also be so configured, but the compression ratio reductio= n would reduce its BSFC and maybe durability advantage. =A0The total operatin= g cost is certainly significantly less if auto gas can always be used to refu= el. =A0I assumed in my assessment that it will only be available 50% of the time. =A0The 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.

=A0

Is the engine less expensive? =A0I 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 it would likely cost just = as much. =A0Is the same true of the rotary? =A0I'm not sure, but you have = to consider the total cost, including engineering of all the parts in the syst= em, not just the core engine. =A0I would love to do a rotary installation, but = I don't think I could justify it by cost reduction.

=A0

It wasn't mentioned in the posts, but some have claimed the rotary is "smoother" than a recip. =A0I at first resisted that notion. =A0Sure, any rotary given sufficient counterbalancing, is perfectly balanced. =A0A 4-cylinder opposed recip is not - there is a significant secondary couple. =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. =A0And then consider the forces within the engine that have to be resisted by that long, heavy, but flexible crankshaft. =A0So it isn't the mechanical bal= ance that gives the rotary an advantage. =A0Let's take a look at the the torsional pulsations, comparing the 3-rotor against the 6-cylinder: =A0A 6-cylinder engine has 3 power impulses per rotation, as does the 3-rotor, s= o they are the same, right? =A0Wrong. =A0They both incorporate 4 "stroke" cycles, meaning that there separate and sequential intak= e, compression, power and exhaust events so that is the same for both. =A0The power event, which is the source of the torque impulse,=A0takes 1/2 of a crank rotation for the recip. =A0In the rotary the power event requires 1/4 of a ROTOR rotation, but the rotor rotates at 1/3 crank rotation - the resu= lt is that the power impulse lasts 3/4 of a CRANK rotation, 50% longer than in= a recip. =A0Therefore, the torsional excitation delivered to the propeller, PSRU and to the airframe is significantly less than for a recip. =A0And if you analyze the actual forces imparted, they go down by the square of the r= pm. =A0The torsional vibration amplitude goes down by a factor of 4 just becaus= e the rpm of the rotary turns about twice as fast. =A0If you've skipped t= o the bottom of the paragraph, as you probably should have :-), yes the rotary is "smoother" - a LOT smoother.. (my apologies to rotary purists, fo= r simplicity I used the word "crankshaft" for both engines)<= /font>

=A0

But just because you can burn auto gas should you? =A0The biggest problems 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. =A0The fuel systems of certified aircraft are not particularly well designed with regar= d to vapor lock. =A0"Fortunately", rotary engines typically have no mechanical fuel pump and are forced to rely on electric pumps. =A0Fortunately 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. =A0I would caution any builders to consider vapor lock possibilities very seriously, much more so if you intend to run auto gas. =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 the non-running pump prevent= s back-feeding). =A0Redundancy was by a "crossfeed" line that could connect the tanks together.

=A0

And thanks, Mark for - probably incorrectly - referring to me as a "good engineer". =A0I'll have to put that in my resume!

=A0

Have a good day,

Gary

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

=A0




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=A0


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