X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.120] verified) by logan.com (CommuniGate Pro SMTP 5.2.3) with ESMTP id 2921376 for flyrotary@lancaironline.net; Wed, 14 May 2008 07:49:40 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.120; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([75.191.186.236]) by cdptpa-omta05.mail.rr.com with SMTP id <20080514114901.WKXQ720.cdptpa-omta05.mail.rr.com@edward2> for ; Wed, 14 May 2008 11:49:01 +0000 Message-ID: <001501c8b5b8$38774690$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Revisiting Rotaries Date: Wed, 14 May 2008 07:46:59 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01C8B596.B10B0370" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_0012_01C8B596.B10B0370 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Humm, perhaps using that activity as an excuse not to mow the lawn?? Thanks Todd, it is easier for old eyeballs to read for sure. =20 Ed ----- Original Message -----=20 From: Todd Bartrim=20 To: Rotary motors in aircraft=20 Sent: Wednesday, May 14, 2008 12:39 AM Subject: [FlyRotary] Revisiting Rotaries I'm not quite sure why I did this, as I'm way to busy to be wasting = time like this but. =20 I thought the 'Revisiting Rotaries' article was worth preserving as a = text file so I took the time and re-typed the entire article = word-for-word (I even resisted the temptation to edit out the PL = reference). This will make it easier for the old eyes in the group to = read J. It's pasted in its entirety below as well as attached in a Word = file. It is tempting to add a few footnotes to bring the article up to = date to reflect some of the advancements made in the last 5 years since = it was written. Things such as Mistral's commercial project, Marcotte's = PSRU with hydraulic output for CS props, Tracy's ever expanding line of = products tailored for the rotary, and the continued success of members = of this list. =20 Todd Bartrim (it should be against the law to turn barley into = ethanol)=20 =20 Revisiting Rotaries By Peter Garrison = June 2003 =20 =20 When I wrote to an old friend, who had built a beautiful Falco = himself, that my homebuilt was at last flying, he replied, "I at the = same time envy you the airplane and think there-but-for-the-grace." I = knew exactly what he meant. Building an airplane is endless trouble, and = once that ends, maintaining it is endless trouble too. But it's sweet = trouble. Time spent taking things apart and putting them together, = machining, drilling, shaping laminating, is, at least for some people, = time well spent. People who don't understand that wonder how you can = stand to spend years alone in a garage or hangar puttering with pieces = of metal and fiberglass. But then they don't understand how a yogi can = spend so much time sitting cross-legged in the snow, either. The population of amateur builders has changed over the = past couple of decades. The majority used to scrounge materials and = build from plans - sometimes, as in the case of the once popular Wittman = Tailwind, very sketchy plans indeed. Today they order hardware and = materials over the Internet from huge suppliers and assemble airplanes = from largely prefabricated kits. Like any old goat who sees the rest of the flock taking a = different route than he, I grouchily disapprove. I fancy the design it = yourself, build it from scratch types are the loftier sort. But when I = arrange amateur builders in a hierarchy that - quite accidentally - = places my category near the top, I still see others higher up. For = however bold may be the enterprise of designing a new airframe and = building it from scratch, it ranks below that of another class of = homebuilders; the ones who build their own engines and test them in the = air. Two factors motivate amateur builders to seek alternative = engines. One is cost. Certified engines, especially ones in the = 200-and-up horsepower class, are prohibitively expensive for ordinary = folk, as are their parts and maintenance. The other is a sense, often = quite intuitive and unfocused, that modern technology must have = something better to offer than engines whose basic plan was laid down = more than half a century ago. The natural place to look for an alternative engine is = under the hood of a car in a wrecking yard. Auto engines are cheap and = readily available, and they come in all shapes and sizes. They are known = to be reliable, though that reliability assumes a duty cycle - 20% of = power most of the time rather than 70% - quite different from the = aeronautical one. Auto engines are much lighter today than they were = when their blocks and heads were made of cast iron, and despite the = added weight and complexity of liquid cooling, one can easily convince = oneself that it offers possibilities of drag reduction and superior = temperature control. A basic problem for aviation applications of auto engines = is that they are designed to deliver their peak power and torque at = nearly twice the rpm at which conventional propellers want to run. The = typical rev limit of around 2700 rpm was chosen by the ancients to allow = propellers of reasonable diameter to maintain subsonic tip speeds = without reduction gearing. A direct-drive engine needs a large = displacement - six to nine liters - to achieve its characteristic = power-to-weight ration of 1.5 pounds per horsepower at low rpm. Auto = engines yield the same power less than half the displacement, but at = twice the crankshaft speed. Gearing an engine down sounds like a simple matter, but it = turns out not to be. The engine delivers it's power in a series of = impulses as cylinders fire one after another. The propeller reacts like = a big springs, it's blades flexing in response. The flywheels and torque = converters that are used in cars to smooth out the power pulses would = add unacceptable weight to an airplane, and so the reduction gears (or = chains or belts) must instead be more robust and carefully manufactured = than you would at first suppose. Nevertheless, people do put auto engines in airplanes and = they do work. Aluminum-block V8s and V6s have been popular, as have = liquid-cooled Subaru flat fours. In my opinion, however, the most = promising engine for aviation use is the Mazda rotary. There are fundamental reasons to prefer the rotary, of = which its famous smoothness is the least important. Compactness is more = important; the fact that it likes to run on auto gasoline helps; but = most important of all is its simplicity. Rotaries consist of a three-sided rotor spinning inside an = oval, slightly eight-shaped case. The three edges of the rotor slide = along the inner surface of the case, forming three separate combustion = chambers whose volumes increase and decrease in turn, like those of = conventional cylinders. In order to ensure complete combustion = throughout the wide, flat combustion chamber, two plugs per cylinder are = standard. Breathing is similar to that of a two-stroke engine, through = openings in the casing that are covered by the moving rotor. There are = no valves, no connecting rods, no camshafts, no crankshaft. What makes the Wankel an appealing engine for aviation is = that long list of parts that it doesn't have. The very few moving parts = that it does have, furthermore, are extremely unlikely to break. The = only thing in the core engine that can fail is one or another of the = apex seals at the corners of the rotors, which are analogous to piston = rings; but even if these break or stick the engine continues to run. The = rotary engine combines, at least potentially, the turbine-like = reliability with the low cost of a simple mass produced engine that does = not require any high-temperature alloys. Mazda engines come in two and three-rotor configurations = of 1.3 and 2.0 litre displacement, with outputs in the 200 and 300-hp = range, respectively. (In auto racing, where they have been very = successful, they achieve more than twice those power levels.) They have = been produced in the millions, and cores are readily available from = discarded cars. They are inexpensive to buy and to overhaul. Naturally it's not that simple. Most of the automotive = accessories - fuel and ignition system, manifolds, exhaust headers, = radiators and so on - are unsuitable for aviation use. Then there is the = matter of the reduction gearing or PSRU (prop speed reduction unit). = These are readily available from several sources, but are suitable for = use only with wood or composite fixed-pitch propellers, not with = conventional oil controlled aluminum constant-speeds. Estimates of the cost of rotary installations for = homebuilt aircraft are all over the map. George Graham of Bradenton, = Florida, reports having spent a mere $2000 on his engine, but doubts = that he could repeat the accomplishment today. His side-by-side two seat = canard does better than 150 knots at 7.5 gph; it has logged more than = 320 hours in the air, on top of an initial 40 on the ground. Ed Anderson = of Matthews, North Carolina, who has flown more than 180 hours in a = rotary powered RV-6A, estimates that powerplant costs might run $5,500 = to $10,000, depending on the builders choices of accessory types and = vendors. Some improvisation may be needed. "We're still not quite to the = buy it and hook it up stage," he comments, but adds that trying = different approaches is what true experimenting is all about. "Once you = standardize it, the experimenting is over." Oregonian Perry Mick dispensed with the reduction unit = altogether, installing a direct-drive ducted fan turning at 5700 rpm on = the back of a Long-EZ. He gets 137 kts at eight gph - not great, but = then again the entry to the fan is largely blocked by the airframe. Anderson estimates that 25 or 30 rotary-powered airplanes = are now flying, many of them Van Grunsven RVs (perhaps because RVs = account for so many homebuilts overall). The current high time = installation on a fixed-wing airplane belongs to Tracy Crook of Bell, = Florida, whose RV-4 has logged over 1,400 hours and serves as a stalking = horse for the rotary-engine community. Crook, who has developed and = tested a full line of accessories for Mazda engines including a PSRU and = computer controlled ignition and fuel-injection systems, has an = excellent website, http://www.rotaryaviation.com. It provides, among = other things, candid discussion of the successes and failures of various = accessory designs, and of the present state of the Mazda-modifying art. = Rotary users have encountered a wide range of difficulties, but they = have invariably involved accessories, not the core engine. Another = extremely active promoter of the rotary - the spider, so to speak, at = the center of the web - is Paul Lamar, who maintains a frenetically busy = internet newsgroup at http://home.earthlink.net/~rotaryeng/. Given all this amateur activity, and if the rotary is so = great, it's natural to wonder why there are no commercial rotaries for = aviation. To be sure, new aircraft engines are few and far between. = Toyota certified an aviation version of the Lexus V8 a few years ago but = has made no attempt as yet to commercialize it. Honda is reported to be = developing an aviation piston engine (and a turbine, too). Continental = developed a four-cylinder diesel under a NASA contract, but then shelved = it. France's Renault has also introduced a four-cylinder aviation turbo = diesel which has a takeoff rating of 230 hp. It weighs about 100 pounds = more than a comparable Continental or Lycoming and consumes about one to = two fewer gallons per hour. It reportedly costs much more than = comparable gasoline engines. I find it hard to understand why these big companies are = interested in getting into the aircraft engine business at all, given = the small size of the market, the great difficulty of getting the few = existing airframe manufactures to try anything new and the rich = potential for generating product liability lawsuits. They must hire very = unreliable consultants. It is perhaps revealing that these tentative = moves all come from huge companies with virtually unlimited funds. = Mazda, which belongs to Ford, is the only company possessing both the = capital necessary to involve itself in the developing an aviation rotary = engine and the technological competence to do so; but, if it ever = considered the possibility, it evidently decided to steer clear. It would be a mistake, however, to apply Darwinian = principles to the aircraft engine business and to conclude that if an = aviation rotary does not exist, it must be that one does not deserve to. = The same argument could have been made a million years ago, about Man. = But, now that I think about it. A 20-year-old NASA study found a 340-hp "stratified charge = omnivorous rotary engine" superior to both a diesel and a small turbine = as a future engine for general aviation. Nevertheless, despite the = participation, at one time or another, of Curtiss-Wright, Lycoming, John = Deere and General Motors in rotary development, the job of making the = rotary into a practical aviation engine has now fallen into the hands of = a bunch of homebuilders. I hope that the combined efforts and ingenuity of these = amateurs will settle, once and for all, the question of the rotary's = suitability for airplanes. I suspect that they will find in its favor. = In the meantime they remain the noblest and most daring of homebuilders, = hairy-chested heroes for whom the evidence that their latest idea was = not a good one may well come in the form of an engine failure just after = takeoff. They continue undaunted, and their numbers increase. The world = owes them a debt of gratitude. =20 =20 -------------------------------------------------------------------------= ----- -- Homepage: http://www.flyrotary.com/ Archive and UnSub: = http://mail.lancaironline.net:81/lists/flyrotary/List.html ------=_NextPart_000_0012_01C8B596.B10B0370 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Humm, perhaps using that activity as an = excuse=20 not to mow the lawn??
 
Thanks Todd, it is easier for old = eyeballs to=20 read for sure. 
 
Ed
----- Original Message -----
From:=20 Todd = Bartrim=20
Sent: Wednesday, May 14, 2008 = 12:39=20 AM
Subject: [FlyRotary] Revisiting = Rotaries

I=92m=20 not quite sure why I did this, as I=92m way to busy to be wasting time = like this=20 but=85

 

I=20 thought the =91Revisiting Rotaries=92 article was worth preserving as = a text file=20 so I took the time and re-typed the entire article word-for-word (I = even=20 resisted the temptation to edit out the PL reference). This will make = it=20 easier for the old eyes in the group to read = J. It=92s=20 pasted in its entirety below as well as attached in a Word file. It is = tempting to add a few footnotes to bring the article up to date to = reflect=20 some of the advancements made in the last 5 years since it was = written. Things=20 such as Mistral=92s commercial project, Marcotte=92s PSRU with = hydraulic output=20 for CS props, Tracy=92s ever expanding line of products tailored for = the rotary,=20 and the continued success of members of this=20 list.

 

Todd=20 Bartrim   = (it=20 should be against the law to turn barley into ethanol) =

 

Revisiting=20 Rotaries

By Peter Garrison           &nbs= p;            = ;            =             &= nbsp;           &n= bsp; =20 June 2003

 

 

When I wrote to=20 an old friend, who had built a beautiful Falco himself, that my = homebuilt was=20 at last flying, he replied, =93I at the same time envy you the = airplane and=20 think there-but-for-the-grace.=94 I knew exactly what he meant. = Building an=20 airplane is endless trouble, and once that ends, maintaining it is = endless=20 trouble too. But it=92s sweet trouble. Time spent taking things apart = and=20 putting them together, machining, drilling, shaping laminating, is, at = least=20 for some people, time well spent. People who don=92t understand that = wonder how=20 you can stand to spend years alone in a garage or hangar puttering = with pieces=20 of metal and fiberglass. But then they don=92t understand how a yogi = can spend=20 so much time sitting cross-legged in the snow, = either.

           =20 The population of amateur builders has changed over the past = couple of=20 decades. The majority used to scrounge materials and build from plans = =96=20 sometimes, as in the case of the once popular Wittman Tailwind, very = sketchy=20 plans indeed. Today they order hardware and materials over the = Internet from=20 huge suppliers and assemble airplanes from largely prefabricated=20 kits.

           =20 Like any old goat who sees the rest of the flock taking a = different=20 route than he, I grouchily disapprove. I fancy the design it yourself, = build=20 it from scratch types are the loftier sort. But when I arrange amateur = builders in a hierarchy that =96 quite accidentally =96 places my = category near=20 the top, I still see others higher up. For however bold may be the = enterprise=20 of designing a new airframe and building it from scratch, it ranks = below that=20 of another class of homebuilders; the ones who build their own engines = and=20 test them in the air.

           =20 Two factors motivate amateur builders to seek alternative = engines. One=20 is cost. Certified engines, especially ones in the 200-and-up = horsepower=20 class, are prohibitively expensive for ordinary folk, as are their = parts and=20 maintenance. The other is a sense, often quite intuitive and = unfocused, that=20 modern technology must have something better to offer than engines = whose basic=20 plan was laid down more than half a century ago.

           =20 The natural place to look for an alternative engine is under = the hood=20 of a car in a wrecking yard. Auto engines are cheap and readily = available, and=20 they come in all shapes and sizes. They are known to be reliable, = though that=20 reliability assumes a duty cycle =96 20% of power most of the time = rather than=20 70% - quite different from the aeronautical one. Auto engines are much = lighter=20 today than they were when their blocks and heads were made of cast = iron, and=20 despite the added weight and complexity of liquid cooling, one can = easily=20 convince oneself that it offers possibilities of drag reduction and = superior=20 temperature control.

           =20 A basic problem for aviation applications of auto engines is = that they=20 are designed to deliver their peak power and torque at nearly twice = the rpm at=20 which conventional propellers want to run. The typical rev limit of = around=20 2700 rpm was chosen by the ancients to allow propellers of reasonable = diameter=20 to maintain subsonic tip speeds without reduction gearing. A = direct-drive=20 engine needs a large displacement =96 six to nine liters =96 to = achieve its=20 characteristic power-to-weight ration of 1.5 pounds per horsepower at = low rpm.=20 Auto engines yield the same power less than half the displacement, but = at=20 twice the crankshaft speed.

           =20 Gearing an engine down sounds like a simple matter, but it = turns out=20 not to be. The engine delivers it=92s power in a series of impulses as = cylinders=20 fire one after another. The propeller reacts like a big springs, = it=92s blades=20 flexing in response. The flywheels and torque converters that are used = in cars=20 to smooth out the power pulses would add unacceptable weight to an = airplane,=20 and so the reduction gears (or chains or belts) must instead be more = robust=20 and carefully manufactured than you would at first = suppose.

           =20 Nevertheless, people do put auto engines in airplanes and they = do work.=20 Aluminum-block V8s and V6s have been popular, as have liquid-cooled = Subaru=20 flat fours. In my opinion, however, the most promising engine for = aviation use=20 is the Mazda rotary.

           =20 There are fundamental reasons to prefer the rotary, of which = its famous=20 smoothness is the least important. Compactness is more important; the = fact=20 that it likes to run on auto gasoline helps; but most important of all = is its=20 simplicity.

           =20 Rotaries consist of a three-sided rotor spinning inside an = oval,=20 slightly eight-shaped case. The three edges of the rotor slide along = the inner=20 surface of the case, forming three separate combustion chambers whose = volumes=20 increase and decrease in turn, like those of conventional cylinders. = In order=20 to ensure complete combustion throughout the wide, flat combustion = chamber,=20 two plugs per cylinder are standard. Breathing is similar to that of a = two-stroke engine, through openings in the casing that are covered by = the=20 moving rotor. There are no valves, no connecting rods, no camshafts, = no=20 crankshaft.

           =20 What makes the Wankel an appealing engine for aviation is that = long=20 list of parts that it doesn=92t have. The very few moving parts that = it does=20 have, furthermore, are extremely unlikely to break. The only thing in = the core=20 engine that can fail is one or another of the apex seals at the = corners of the=20 rotors, which are analogous to piston rings; but even if these break = or stick=20 the engine continues to run. The rotary engine combines, at least = potentially,=20 the turbine-like reliability with the low cost of a simple mass = produced=20 engine that does not require any high-temperature = alloys.

           =20 Mazda engines come in two and three-rotor configurations of 1.3 = and 2.0=20 litre displacement, with outputs in the 200 and 300-hp range, = respectively.=20 (In auto racing, where they have been very successful, they achieve = more than=20 twice those power levels.) They have been produced in the millions, = and cores=20 are readily available from discarded cars. They are inexpensive to buy = and to=20 overhaul.

           =20 Naturally it=92s not that simple. Most of the automotive = accessories =96=20 fuel and ignition system, manifolds, exhaust headers, radiators and so = on =96=20 are unsuitable for aviation use. Then there is the matter of the = reduction=20 gearing or PSRU (prop speed reduction unit). These are readily = available from=20 several sources, but are suitable for use only with wood or composite=20 fixed-pitch propellers, not with conventional oil controlled aluminum=20 constant-speeds.

           =20 Estimates of the cost of rotary installations for homebuilt = aircraft=20 are all over the map. George Graham of Bradenton, Florida, reports = having=20 spent a mere $2000 on his engine, but doubts that he could repeat the=20 accomplishment today. His side-by-side two seat canard does better = than 150=20 knots at 7.5 gph; it has logged more than 320 hours in the air, on top = of an=20 initial 40 on the ground. Ed Anderson of Matthews, North Carolina, who = has=20 flown more than 180 hours in a rotary powered RV-6A, estimates that = powerplant=20 costs might run $5,500 to $10,000, depending on the builders choices = of=20 accessory types and vendors. Some improvisation may be needed. = =93We=92re still=20 not quite to the buy it and hook it up stage,=94 he comments, but adds = that=20 trying different approaches is what true experimenting is all about. = =93Once you=20 standardize it, the experimenting is over.=94

           =20 Oregonian Perry Mick dispensed with the reduction unit = altogether,=20 installing a direct-drive ducted fan turning at 5700 rpm on the back = of a=20 Long-EZ. He gets 137 kts at eight gph =96 not great, but then again = the entry to=20 the fan is largely blocked by the airframe.

           =20 Anderson estimates that 25 or 30 rotary-powered airplanes are = now=20 flying, many of them Van Grunsven RVs (perhaps because RVs account for = so many=20 homebuilts overall). The current high time installation on a = fixed-wing=20 airplane belongs to Tracy Crook of Bell, Florida, whose RV-4 has = logged over=20 1,400 hours and serves as a stalking horse for the rotary-engine = community.=20 Crook, who has developed and tested a full line of accessories for = Mazda=20 engines including a PSRU and computer controlled ignition and = fuel-injection=20 systems, has an excellent website, http://www.rotaryaviation.com. It = provides,=20 among other things, candid discussion of the successes and failures of = various=20 accessory designs, and of the present state of the Mazda-modifying = art. Rotary=20 users have encountered a wide range of difficulties, but they have = invariably=20 involved accessories, not the core engine. Another extremely active = promoter=20 of the rotary =96 the spider, so to speak, at the center of the web = =96 is Paul=20 Lamar, who maintains a frenetically busy internet newsgroup at http://home.earthlink.net/= ~rotaryeng/.

           =20 Given all this amateur activity, and if the rotary is so great, = it=92s=20 natural to wonder why there are no commercial rotaries for aviation. = To be=20 sure, new aircraft engines are few and far between. Toyota certified = an=20 aviation version of the Lexus V8 a few years ago but has made no = attempt as=20 yet to commercialize it. Honda is reported to be developing an = aviation piston=20 engine (and a turbine, too). Continental developed a four-cylinder = diesel=20 under a NASA contract, but then shelved it. France=92s Renault has = also=20 introduced a four-cylinder aviation turbo diesel which has a takeoff = rating of=20 230 hp. It weighs about 100 pounds more than a comparable Continental = or=20 Lycoming and consumes about one to two fewer gallons per hour. It = reportedly=20 costs much more than comparable gasoline engines.

           =20 I find it hard to understand why these big companies are = interested in=20 getting into the aircraft engine business at all, given the small size = of the=20 market, the great difficulty of getting the few existing airframe = manufactures=20 to try anything new and the rich potential for generating product = liability=20 lawsuits. They must hire very unreliable consultants. It is perhaps = revealing=20 that these tentative moves all come from huge companies with virtually = unlimited funds. Mazda, which belongs to Ford, is the only company = possessing=20 both the capital necessary to involve itself in the developing an = aviation=20 rotary engine and the technological competence to do so; but, if it = ever=20 considered the possibility, it evidently decided to steer=20 clear.

           =20 It would be a mistake, however, to apply Darwinian principles = to the=20 aircraft engine business and to conclude that if an aviation rotary = does not=20 exist, it must be that one does not deserve to. The same argument = could have=20 been made a million years ago, about Man. But, now that I think about=20 it=85

           =20 A 20-year-old NASA study found a 340-hp =93stratified charge = omnivorous=20 rotary engine=94 superior to both a diesel and a small turbine as a = future=20 engine for general aviation. Nevertheless, despite the participation, = at one=20 time or another, of Curtiss-Wright, Lycoming, John Deere and General = Motors in=20 rotary development, the job of making the rotary into a practical = aviation=20 engine has now fallen into the hands of a bunch of=20 homebuilders.

           =20 I hope that the combined efforts and ingenuity of these = amateurs will=20 settle, once and for all, the question of the rotary=92s suitability = for=20 airplanes. I suspect that they will find in its favor. In the meantime = they=20 remain the noblest and most daring of homebuilders, hairy-chested = heroes for=20 whom the evidence that their latest idea was not a good one may well = come in=20 the form of an engine failure just after takeoff. They continue = undaunted, and=20 their numbers increase. The world owes them a debt of=20 gratitude.

 

 

--
Homepage:  http://www.flyrotary.com/
Archive and=20 UnSub:  =20 = http://mail.lancaironline.net:81/lists/flyrotary/List.html
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