If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
subaru diesel
Bill Daniels wrote:
The Subaru oil burner looks good but then so does the DeltaHawk and the little opposed piston aircraft diesels from the UK. Not really as good as someone think... It's too heavy (178kg, 400lb). I prefer a true airplane engine like WAM120 or WAM160 http://www.wilksch.com/ They shipped some 120Hp 3 cylinder engines, but I don' know if they shipped any 160HP 4 cylinder engines. Both engines will work fine in a RV9... At this time, the WAM creator will be hired by Continental... Is WAM engines will be certified and continetal branded? About diesel mania, remember the avgas cost is twice the diesel cost in Europe; 100LL cost more than $10 one gallon. By -- Volem rien foutre al païs! Philippe Vessaire Ò¿Ó¬ |
#12
|
|||
|
|||
subaru diesel
clare at snyder dot ontario dot canada wrote:
Torque curve page 6 http://www.subaru.fr/special/pdf/doc...esel_lo_08.pdf Holy crap! That thing has the peak torque, and it is almost a level line, from about 1600 rpm to about 2400 rpm! That sucker should really pull a big prop, and well! Like I said! At 2400 rpm, you only got 90KW or 120Hp, not enough for a 400lb engine. Remember: power matter for flight..... By -- Volem rien foutre al païs! Philippe Vessaire Ò¿Ó¬ |
#13
|
|||
|
|||
subaru diesel
wrote in message ... On Mar 22, 9:33 pm, "Dale Scroggins" wrote: "Blueskies" wrote in message ... "Morgans" wrote in message ... "Philippe Vessaire" wrote in message news:19459447.yEvPs9oxTh@GastonCoute... Hello Torque curve page 6 http://www.subaru.fr/special/pdf/doc...esel_lo_08.pdf Holy crap! That thing has the peak torque, and it is almost a level line, from about 1600 rpm to about 2400 rpm! That sucker should really pull a big prop, and well! -- Jim in NC Is the price of diesel fuel 25% above gasoline prices everywhere? Jet A costs the same as 100LL now also, so what is the benefit? SNIP 2. No ignition system needed. Not to be a ball-buster, but the injection systems for the new generation of diesels is incredibly fancy. From a risk analysis standpoint, it is hard to say whether this system in place of magnetos is a gain or a loss. 3. Turbocharging a diesel is a win-win proposition. EGT is lower, so turbo system parts last as long as the engine, usually. Turbocharging improves both performance and fuel efficiency (not always true for gassers). True, but boost levels in diesels inversely effect their reputation for reliability. SNIP 8. I can make biodiesel for 67 cents a gallon. You or I can buy off-road diesel or heating oil for much less than either auto gas, avgas or jet A. Biodiesel gels at a higher temp than does winter diesel, and be damned sure you have no rubber in the fuel system. And the 67 cents is quoted for recycled oil. Not my first pick at altitude. 9. For a given trip, less fuel is needed, both in volume and weight. 25% to 35%, depending on the trip profile. If the diesel is turbocharged and gasser is not, the diesel's ability to cruise significantly higher may result in a bigger efficiency spread. This is dependent on tuning the boost map, and whether the blower is big enough. Off the shelf this may or may not be true. I have not read flight tests for any new European diesels which have been impressive in high altitude performance. I doubt this is because of any fundemental flaws, but rather performance tuning. 10. Props are more efficient at lower RPMs, usually. Diesels have torque to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving maybe another 5% efficiency gain, and a quieter cabin to boot. Given time, I can think of more. Please note that gas engines were abandoned decades, nay, scores of years ago in other transportation sectors. It will be the same in aviation if the weight difference shrinks enough. DS I dig your enthusiasm. Please post if you hear of any new diesel/ biodiesel aviation projects. I would be interested in reading any related results. I believe that the new generation of diesels are the long term solution for keeping GA operating costs down. But it will take a while. -Matt Why any sort of reciprocating engine?...small turboprops would be the best solution of they can get the mass fuel flow problems resolved... |
#14
|
|||
|
|||
subaru diesel
"Dale Scroggins" wrote The SmartCar aluminum diesel engine and the Toyota Yaris engine (Europe, aluminum diesel) might be good candidates for small aircraft. However, this Subaru seems to be an ideal candidate since its power and weight specs fit so many available airframes. PRSUs are also available. I suspect we will see these engines installed fairly quickly in European experimentals. No need for a PSRU. The torque band makes it perfect for direct drive. -- Jim in NC |
#15
|
|||
|
|||
subaru diesel
On Sun, 23 Mar 2008 08:31:29 -0400, "Morgans"
wrote: "Dale Scroggins" wrote The SmartCar aluminum diesel engine and the Toyota Yaris engine (Europe, aluminum diesel) might be good candidates for small aircraft. However, this Subaru seems to be an ideal candidate since its power and weight specs fit so many available airframes. PRSUs are also available. I suspect we will see these engines installed fairly quickly in European experimentals. No need for a PSRU. The torque band makes it perfect for direct drive. And the weight is not necessarily a killer. Likely a lot that can be removed from the automotive application - and there have been many heavier, lower powered engines thoughout aviation history. Think Model "A" Ford. 28 HP and 200+ pounds. Lots of others too. -- Posted via a free Usenet account from http://www.teranews.com |
#16
|
|||
|
|||
subaru diesel
"Dale Scroggins" wrote in message
... ... 1. Most diesels wear more slowly than gas engines. The fuel is a better lubricant than gasoline is, and the combustion products are a bit more benign. Except, of course, for the particulates. Particulates are hell on bearings, and lungs, and... NOx tends to run higher and isn't usually clasified as "benign" 5. Automatic mixture control. "mixture control is irrelevent" would be a more accurate statement. 7. Lower fire risks. Not really. 10. Props are more efficient at lower RPMs, usually. Diesels have torque to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving maybe another 5% efficiency gain, and a quieter cabin to boot. Depends on how the engine was designed, not how the fuel is ignited. Given time, I can think of more. Please note that gas engines were abandoned decades, nay, scores of years ago in other transportation sectors. It will be the same in aviation if the weight difference shrinks enough. Well, there's the problem, isn't it. Making a light weight diesel that will last. Note: I'm not suggesting that diesels are a bad idea - they do have there advantages. But, let's not over sell... -- Geoff The Sea Hawk at Wow Way d0t Com remove spaces and make the obvious substitutions to reply by mail When immigration is outlawed, only outlaws will immigrate. |
#17
|
|||
|
|||
subaru diesel
"Capt. Geoffrey Thorpe" The Sea Hawk At Wow Way D0t C0m wrote in message news:N6adnXfOAtwpgHXanZ2dnUVZ_sWdnZ2d@wideopenwest .com... "Dale Scroggins" wrote in message ... ... 1. Most diesels wear more slowly than gas engines. The fuel is a better lubricant than gasoline is, and the combustion products are a bit more benign. Except, of course, for the particulates. Particulates are hell on bearings, and lungs, and... NOx tends to run higher and isn't usually clasified as "benign" The specific comparison I had in mind was a current-production piston aircraft engine burning 100LL, compared to a current-production automotive diesel engine. Given a choice of the lead compounds that collect within and are emitted by the gasser, and the low levels of particulates deposited and emitted by a current-production automotive diesel, I'd prefer the particulates. As to oxides of nitrogen, given that current production gas aviation engines run with advanced ignition timing, have no EGR, and operate at elevated EGT most of the time, I doubt a current production auto diesel would produce more NOx, and would likely produce less. I'm open to numbers, if you have them. Again, my comparison was between current diesels and current gas aircraft engines, not current automotive gas engines. 5. Automatic mixture control. "mixture control is irrelevent" would be a more accurate statement. For a turbodiesel, "automatic mixture control" is a more accurate statement. Mixture control is quite relevent, and automatically managed. 7. Lower fire risks. Not really. Hmm. So the dozens of induction fires (some of which caused substantial damage) that I've witnessed over the years are just as likely with a diesel engine? And all the extra precautions we followed over the years when fueling and defueling avgas (or mogas), compared to jetA, were a waste of time? 10. Props are more efficient at lower RPMs, usually. Diesels have torque to turn props slow in cruise, like a turboprop (1800-1900 RPM), giving maybe another 5% efficiency gain, and a quieter cabin to boot. Depends on how the engine was designed, not how the fuel is ignited. Hmm again. So the burn characteristics of the fuel, the ability to inject additional fuel after initiation of combustion, and the surplus of available oxygen have no impact on engine torque curves? Given time, I can think of more. Please note that gas engines were abandoned decades, nay, scores of years ago in other transportation sectors. It will be the same in aviation if the weight difference shrinks enough. Well, there's the problem, isn't it. Making a light weight diesel that will last. Note: I'm not suggesting that diesels are a bad idea - they do have there advantages. But, let's not over sell... Wasn't the prospect of a relatively light weight diesel available to homebuilders the point of this thread? No one knows if Subaru's diesel will match the durability of a current-production avgas engine. However, newer diesel injection methods have helped reduce internal engine forces, so durable, light diesel engines are on the horizon. What do you see as the advantages of diesel aircraft engines? DS |
#18
|
|||
|
|||
subaru diesel
"Morgans" wrote in message ... "Dale Scroggins" wrote The SmartCar aluminum diesel engine and the Toyota Yaris engine (Europe, aluminum diesel) might be good candidates for small aircraft. However, this Subaru seems to be an ideal candidate since its power and weight specs fit so many available airframes. PRSUs are also available. I suspect we will see these engines installed fairly quickly in European experimentals. No need for a PSRU. The torque band makes it perfect for direct drive. -- Jim in NC It's going to need a starter; diesels are hard to hand prop. And the engine is not likely designed to handle thrust and gyroscopic loads. So, because of starter placement and need for a well-supported prop shaft, a nose-piece casting with bearings and a prop shaft will be needed. Incorporating reduction gearing (or belt) and a device to smooth power pulses wouldn't add much additional weight. The torque curve isn't flat to maximum power. If a fixed-pitch prop is installed that is efficient at low RPM, the engine may not be able to make take-off RPM without a bit of mechanical advantage - or variable pitch, which leads back to the PSRU. Since Subaru is hinting that a 200 hp version is on its way (giving even better hp/weight ratio), a variable pitch prop should be considered. DS |
#19
|
|||
|
|||
subaru diesel
"Dale Scroggins" wrote It's going to need a starter; diesels are hard to hand prop. And the engine is not likely designed to handle thrust and gyroscopic loads. Many auto engine cranks have done well with these loads, and no extra help. So, because of starter placement Alternate starter schemes may be developed, and might save weight. and need for a well-supported prop shaft, a nose-piece casting with bearings and a prop shaft will be needed. Not a given, IMHO. Incorporating reduction gearing (or belt) and a device to smooth power pulses Smoothing power pulses results in heating up the device, which means it is robbing power and efficiency. Double or triple bad thing. Weight, power, and reliability. wouldn't add much additional weight. I've heard that so many times, and it all adds up to an overweight airplane. The torque curve isn't flat to maximum power. True, but how much extra power will have to be made, to haul around the extra weight? If a fixed-pitch prop is installed that is efficient at low RPM, the engine may not be able to make take-off RPM without a bit of mechanical advantage - or variable pitch, which leads back to the PSRU. PSRU's are HEAVY! Why add one, if it is not absolutely needed? Extra weight has to be well justified, as does the possibility of extra components causing possible extra failures. It is hard to imagine that hauling around the extra weight could be justified, with a torque curve like that engine. It would need to make a lot of extra HP to justify a PSRU, to me. Since Subaru is hinting that a 200 hp version is on its way (giving even better hp/weight ratio), a variable pitch prop should be considered. Why? With conventional aircraft engines, they make best power and torque at up around 2700 RPM. If you have to run too big of a prop to utilize 200 HP, then you need constant speed to keep from breaking supersonic. If you have an engine running best power (or close to it) and best torque at 23 or 24 hundred RPM, you can run a bigger prop, and keep the tips slow enough, without the extra weight and complexity of constant speed props. Don't get me wrong. I'm not against PSRU's in all cases. I am against extra weight and complexity when it is not absolutely necessary. I don't think a clear case has been made, for this engine. Wait until it is being used, and see how well it does, is my opinion. It will let us know, by how it does after it has been eXperimented with, I believe. You may be surprised. I might be, too. Until then, keep an open mind. -- Jim in NC |
#20
|
|||
|
|||
subaru diesel
Morgans" wrote: "Dale Scroggins" wrote It's going to need a starter; diesels are hard to hand prop. And the engine is not likely designed to handle thrust and gyroscopic loads. Many auto engine cranks have done well with these loads, and no extra help. Name 'em and define what you mean by 'no extra help'? and need for a well-supported prop shaft, a nose-piece casting with bearings and a prop shaft will be needed. Not a given, IMHO. YES.... 'a given' or something very close to one for safety sake. Wait until it is being used, and see how well it does, is my opinion. It will let us know, by how it does after it has been eXperimented with, I believe. You may be surprised. I might be, too. Until then, keep an open mind. Aw phoof! A promising answer or solution is always just around the corner. In the meantime, I guess you can fly around in a baloon filled with the hot air generated here! - Barnyard BOb - |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
New diesel engine from Subaru... | [email protected] | Home Built | 16 | March 21st 08 02:31 AM |
Diesel Jodel information..........and .........diesel plane groups | Roland M | Owning | 1 | January 4th 04 04:04 AM |
Diesel engines for Planes Yahoo Group Jodel Diesel is Isuzu Citroen Peugeot | Roland M | Home Built | 3 | September 13th 03 12:44 AM |
Diesel engines for Planes Yahoo Group Jodel Diesel is Isuzu Citroen Peugeot | Roland M | General Aviation | 2 | September 13th 03 12:44 AM |
Diesel engines for Planes Yahoo Group Jodel Diesel is Isuzu Citroen Peugeot | Roland M | Rotorcraft | 2 | September 13th 03 12:44 AM |