Aircraft possibilities
08-24-06, 05:24 PM
#26
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Originally Posted by Aviator 902S
Agreed. Most AME types are very biased against any auto conversion and homebuilt aircraft in general. Even those few who are also pilots cast a very jaundiced eye on anything that doesn't require the services of an AME to (legally) maintain. (Conflict of interest, perhaps?)
My father was a career fighter and test pilot and took a little bit of joy in constantly referring to kit planes as, "flying deathtraps."
08-24-06, 05:42 PM
#27
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You can build a C-I rated Cub. All it has to do is have a empty weight under 1200lbs. THen you can use any engine you want ( it would clasify as an ultralight). Also if you build the Cub yourself it is a homebuilt and if I recolect corectly it can way anything you want (engien wise), and does not require certifed aircraft engines. Only a certified aircraft ( production aircraft) need certified engines.
Also a Cub is not rated to fly over 12 500 feet so Turbo normalization for high altitude flight is not an issue.
at that alttitude you may be losing 20ish hp but since the air is thiner the cruse speed should remain the same, or posibly increase a little. Either way at 12 500ft you will still get hypoxia pritty quick so you won't be spendgin a hole lot of time up that high.
Also a Cub is not rated to fly over 12 500 feet so Turbo normalization for high altitude flight is not an issue.
at that alttitude you may be losing 20ish hp but since the air is thiner the cruse speed should remain the same, or posibly increase a little. Either way at 12 500ft you will still get hypoxia pritty quick so you won't be spendgin a hole lot of time up that high.
08-24-06, 06:57 PM
#28
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Originally Posted by Aaron Cake
What sort of liability is attached to building an engine for an aircraft? Something I've always wondered...
Still, most who sell a non-certified engine to someone who wants to use that engine in an aircraft will insist the buyer sign a rider stating that the engine will not be installed in an aircraft--- just in case some hot-shot lawyer tries to do an end run around the law in order to sucessfully sue whoever has the most money.
But (so far, at least in Canada) such lawsuits over homebuilt aircraft mishaps are almost unheard of. That's not to say it couldn't happen though.
08-24-06, 07:06 PM
#29
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Originally Posted by Feds
See, I told you that you could fall out of the sky 
You'll never catch me in a homebuilt, or more than line-of-sight from shore, but at the same time, 2 of my cars and my motorcycle are basically built ground-up by me in my garage.
Different risk tolerance.
You'll never catch me in a homebuilt, or more than line-of-sight from shore, but at the same time, 2 of my cars and my motorcycle are basically built ground-up by me in my garage.
Different risk tolerance.
Statistically the risk is really no greater than that of riding a motorcycle, but the perceived risk depends on the induvidual and the degree of that induvidual's fear of flying. Some people would rather swim across a crocodile-infested stream than go up in a small plane, even though the risk of the swim would appear much higher to most people.
08-25-06, 12:19 AM
#30
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Originally Posted by Aviator 902S
Agreed. Most AME types are very biased against any auto conversion and homebuilt aircraft in general.
<snip>...
[/i]Tracy Crook (whose work I have followed since long before most had ever heard of him) answers just about any question you may have on rotary engined aircraft. His Renesis-powered RV4 sport plane has a firewall-forward weight of just over 300 lbs--- about 60 lbs less than that of the Lycoming O-320 installation that it replaces and upwards of 40 more horses. All this with a time-before-overhaul (TBO) equal to or greater than that of the certified Lycoming engine (!) He is currently building a 20B-powered RV8--- which is like an RV4 on steroids.
One caveat to the rotary engine used in aircraft is harmonics and the effects they can have on propellers. The rotary has way less vibration than aircraft piston engines do, but the frequency of the vibration that is present is much higher. This resonance, when resonating at the same frequency as the prop at certain rpms, can cause the prop to fail catastrophically. This is a problem with metal props, but going with either a wood or composite prop will cure this trait.
<snip>...
[/i]Tracy Crook (whose work I have followed since long before most had ever heard of him) answers just about any question you may have on rotary engined aircraft. His Renesis-powered RV4 sport plane has a firewall-forward weight of just over 300 lbs--- about 60 lbs less than that of the Lycoming O-320 installation that it replaces and upwards of 40 more horses. All this with a time-before-overhaul (TBO) equal to or greater than that of the certified Lycoming engine (!) He is currently building a 20B-powered RV8--- which is like an RV4 on steroids.
One caveat to the rotary engine used in aircraft is harmonics and the effects they can have on propellers. The rotary has way less vibration than aircraft piston engines do, but the frequency of the vibration that is present is much higher. This resonance, when resonating at the same frequency as the prop at certain rpms, can cause the prop to fail catastrophically. This is a problem with metal props, but going with either a wood or composite prop will cure this trait.
makes a lot of valid points.Wankel engines are a valid alternative to traditional aircraft engines, however, an auto conversion is a LOT of work and you or whoever does the conversion has a lot of homework to do (guess how I found out?) to get it right.
Certified aircooled engines have several advantages. The larger displacement (say O -320 cubic inch) allows a simple engine to produce 150hp at a relatively low 2700rpm direct drive relatively reliably for 2000?hours or so. This same engine converted to auto use could probably pump out 300+hp peak less reliably. The engine is also air cooled which has the advantage of simplicity and disadvantages such as shock cooling.
The major advantage of certified engines is the fact they have been around soo long (50+ years) that most of major bugs have been worked out and many people know about them. The fact that few engines will make it to the 2000 hour TBO with original components (read cylinder, crank,... problems) does not seem to bother most people. Buying a used aircraft engine is riskier than buying a used car from a used car salesman with all of the lightly used/maintained aircraft around.
The wankel is a cheap alternative that can reliably deliver a higher power to weight than certified engines at a higher rpm as witnessed by Tracy Crook, Atkins and others. It does mean that YOU have to pioneer and work out all of the bugs before they succeed in trying to kill you. Fortunately many groups are exchanging knowledge and best practices. There are also pioneering outfits out there such as Tracy Crook (rotary aviation, with a name like that you gotta be doubly honest and he is), Powersport, Mistral and Atkins who have done research, design and testing. You would be wise to join some of the online groups, copy a proven installation and purchase products from some of thse companies or be prepared to do a lot of test/piloting.
The wankel also offers better failure modes that aircooled engines, however, the reality is few(2500h gyro?) have yet made the magical 2000h mark. It will take some time before enough data can support such claims. Also, most installations to date have been radically different so it would be hard to draw conclusions. Most failures to date have not been with the core engine but alternators, coolant leaks, oil leaks, exhaust failures...lots of details can bring you down and liquid cooled wankels have more details.
I am also somewhat concerned lately about new products such after market cermet/whatever seals and coatings. Particularly, when few details are published on specs, testing,...they may in fact be great. It is annoying when your engine pops in a car, it really sucks over buildings, trees, rocks, water in a plane.
As an additional note, all engines have resonances and torsional resonances. Note that some certified aircraft have no fly engine/prop combinations. These can cause premature catastrophic fatigue failure in the prop, prop shaft, crank, eshaft(ok, not yet), redrive.... Tracy Crooks' damper appears to have dealt with them rather well, I assume the other vendors have dampers as well.
With regards homebuilts vs certified, I always joke than I don't feel comfortable in an airplane that is younger than me...
I am just as interested in who built a homebuilt as I am in the maintainer of a certified aircraft before I get in it. I have seen more problems (read there is usually something broken) with rental aircraft than homebuilts...
RVs and Lancairs (...) also look cooler, fly faster and cost way less...
Another opinion
Cheers
Cary
08-25-06, 12:32 AM
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Originally Posted by coldfire
Would a turbo actually be a good idea for these things?
the whole constant load issue. I mean, just imagine a turbo at full boost for 4 hours straight or something...
the whole constant load issue. I mean, just imagine a turbo at full boost for 4 hours straight or something...
Most aircraft do something called turbo-normalization which means they boost just enough to provide sea level pressure up to whatever altitude (perhaps a wee bit more
. Aircraft turbo use is generally quite conservative as most things are geared towards reliability.Cheers
Cary
08-25-06, 01:00 AM
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Originally Posted by no_name
You can build a C-I rated Cub. All it has to do is have a empty weight under 1200lbs. THen you can use any engine you want ( it would clasify as an ultralight). Also if you build the Cub yourself it is a homebuilt and if I recolect corectly it can way anything you want (engien wise), and does not require certifed aircraft engines. Only a certified aircraft ( production aircraft) need certified engines.
Also a Cub is not rated to fly over 12 500 feet so Turbo normalization for high altitude flight is not an issue.
at that alttitude you may be losing 20ish hp but since the air is thiner the cruse speed should remain the same, or posibly increase a little. Either way at 12 500ft you will still get hypoxia pritty quick so you won't be spendgin a hole lot of time up that high.
Also a Cub is not rated to fly over 12 500 feet so Turbo normalization for high altitude flight is not an issue.
at that alttitude you may be losing 20ish hp but since the air is thiner the cruse speed should remain the same, or posibly increase a little. Either way at 12 500ft you will still get hypoxia pritty quick so you won't be spendgin a hole lot of time up that high.
Turbo normalization is an option, although probably a waste unless you want to go above 18k (shiver) with such a plane. HP is 50%@18k, 75% @ 9k. True airspeed is higher due to reduced air density (friction).
I would be more concerned about structural Vne/flutter speeds.
I assume the original 12500' limit (ceiling) was due to HP, wing loading and span loading, a higher HP wankel would have a much higher ceiling.
There are legal O2 requirements, hypoxia is an issue, it will give you warm and fuzzies but not as quickly as people will have you believe. Don't take my word for it - Experience it for yourself, it's fun!
Cheers
08-25-06, 12:47 PM
#33
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this sounds pretty typical of most 'cert or nothing people' ,
Thier is a difference between a pistion and rotary ' auto conversion' this should be glaringly evident in the countless hrs logged by the rotory and subsequent teardowns that show no wear.
larger displacement? low rpm tq? i't scalled a reduction gear.. any motor can be put into the right powerband / prop speed with one. Your argument is the smae one the V8 conversion guys use for thier need to do a swap.. they want the low end tq... for what? pulling a boat? your aircraft pulling a boat and you don't have access to a reduction gear.. that argument is flawed on our part.
thier is no advantage your using a motor that is 50 years old and for legal reasons they can't upgrade.. everything HAS to be made to the specs of 50 years ago or more.. which meants the typical head cracks on the conti will contine. By your reasoning you might as well go back to using a flathead ford or stove pipe six , since naything newer is not 50 years old.. So your'll stick to outdated technology, serviced by people who make a fortune off the serviceing and parts companies that make an even bigger fortune off the purchase of parts for those servicing.. yeah I can see why the promotion of 'new' is not pushed you guys are suckers.
Pioneer?? where do you get this , thier are 1000's of flying hrs on these motors now. In all sorts of aircraft doing all sorts of jobs.. thier is no pioneering left it's simply refinement and improving design .. this is something that can never be done with a certified engine.
Failures have been almost solely due to home built installations and the people having no clue how to do a proper firewall forward package nor how to build or spec the proper materials for the buld of a rotary always ON power.
Thier is a difference between a pistion and rotary ' auto conversion' this should be glaringly evident in the countless hrs logged by the rotory and subsequent teardowns that show no wear.
larger displacement? low rpm tq? i't scalled a reduction gear.. any motor can be put into the right powerband / prop speed with one. Your argument is the smae one the V8 conversion guys use for thier need to do a swap.. they want the low end tq... for what? pulling a boat? your aircraft pulling a boat and you don't have access to a reduction gear.. that argument is flawed on our part.
thier is no advantage your using a motor that is 50 years old and for legal reasons they can't upgrade.. everything HAS to be made to the specs of 50 years ago or more.. which meants the typical head cracks on the conti will contine. By your reasoning you might as well go back to using a flathead ford or stove pipe six , since naything newer is not 50 years old.. So your'll stick to outdated technology, serviced by people who make a fortune off the serviceing and parts companies that make an even bigger fortune off the purchase of parts for those servicing.. yeah I can see why the promotion of 'new' is not pushed you guys are suckers.
Pioneer?? where do you get this , thier are 1000's of flying hrs on these motors now. In all sorts of aircraft doing all sorts of jobs.. thier is no pioneering left it's simply refinement and improving design .. this is something that can never be done with a certified engine.
Failures have been almost solely due to home built installations and the people having no clue how to do a proper firewall forward package nor how to build or spec the proper materials for the buld of a rotary always ON power.
Originally Posted by trydis7
The aviator makes a lot of valid points.
Wankel engines are a valid alternative to traditional aircraft engines, however, an auto conversion is a LOT of work and you or whoever does the conversion has a lot of homework to do (guess how I found out?) to get it right.
Certified aircooled engines have several advantages. The larger displacement (say O -320 cubic inch) allows a simple engine to produce 150hp at a relatively low 2700rpm direct drive relatively reliably for 2000?hours or so. This same engine converted to auto use could probably pump out 300+hp peak less reliably. The engine is also air cooled which has the advantage of simplicity and disadvantages such as shock cooling.
The major advantage of certified engines is the fact they have been around soo long (50+ years) that most of major bugs have been worked out and many people know about them. The fact that few engines will make it to the 2000 hour TBO with original components (read cylinder, crank,... problems) does not seem to bother most people. Buying a used aircraft engine is riskier than buying a used car from a used car salesman with all of the lightly used/maintained aircraft around.
The wankel is a cheap alternative that can reliably deliver a higher power to weight than certified engines at a higher rpm as witnessed by Tracy Crook, Atkins and others. It does mean that YOU have to pioneer and work out all of the bugs before they succeed in trying to kill you. Fortunately many groups are exchanging knowledge and best practices. There are also pioneering outfits out there such as Tracy Crook (rotary aviation, with a name like that you gotta be doubly honest and he is), Powersport, Mistral and Atkins who have done research, design and testing. You would be wise to join some of the online groups, copy a proven installation and purchase products from some of thse companies or be prepared to do a lot of test/piloting.
The wankel also offers better failure modes that aircooled engines, however, the reality is few(2500h gyro?) have yet made the magical 2000h mark. It will take some time before enough data can support such claims. Also, most installations to date have been radically different so it would be hard to draw conclusions. Most failures to date have not been with the core engine but alternators, coolant leaks, oil leaks, exhaust failures...lots of details can bring you down and liquid cooled wankels have more details.
I am also somewhat concerned lately about new products such after market cermet/whatever seals and coatings. Particularly, when few details are published on specs, testing,...they may in fact be great. It is annoying when your engine pops in a car, it really sucks over buildings, trees, rocks, water in a plane.
As an additional note, all engines have resonances and torsional resonances. Note that some certified aircraft have no fly engine/prop combinations. These can cause premature catastrophic fatigue failure in the prop, prop shaft, crank, eshaft(ok, not yet), redrive.... Tracy Crooks' damper appears to have dealt with them rather well, I assume the other vendors have dampers as well.
With regards homebuilts vs certified, I always joke than I don't feel comfortable in an airplane that is younger than me...
I am just as interested in who built a homebuilt as I am in the maintainer of a certified aircraft before I get in it. I have seen more problems (read there is usually something broken) with rental aircraft than homebuilts...
RVs and Lancairs (...) also look cooler, fly faster and cost way less...
Another opinion
Cheers
Cary
makes a lot of valid points.Wankel engines are a valid alternative to traditional aircraft engines, however, an auto conversion is a LOT of work and you or whoever does the conversion has a lot of homework to do (guess how I found out?) to get it right.
Certified aircooled engines have several advantages. The larger displacement (say O -320 cubic inch) allows a simple engine to produce 150hp at a relatively low 2700rpm direct drive relatively reliably for 2000?hours or so. This same engine converted to auto use could probably pump out 300+hp peak less reliably. The engine is also air cooled which has the advantage of simplicity and disadvantages such as shock cooling.
The major advantage of certified engines is the fact they have been around soo long (50+ years) that most of major bugs have been worked out and many people know about them. The fact that few engines will make it to the 2000 hour TBO with original components (read cylinder, crank,... problems) does not seem to bother most people. Buying a used aircraft engine is riskier than buying a used car from a used car salesman with all of the lightly used/maintained aircraft around.
The wankel is a cheap alternative that can reliably deliver a higher power to weight than certified engines at a higher rpm as witnessed by Tracy Crook, Atkins and others. It does mean that YOU have to pioneer and work out all of the bugs before they succeed in trying to kill you. Fortunately many groups are exchanging knowledge and best practices. There are also pioneering outfits out there such as Tracy Crook (rotary aviation, with a name like that you gotta be doubly honest and he is), Powersport, Mistral and Atkins who have done research, design and testing. You would be wise to join some of the online groups, copy a proven installation and purchase products from some of thse companies or be prepared to do a lot of test/piloting.
The wankel also offers better failure modes that aircooled engines, however, the reality is few(2500h gyro?) have yet made the magical 2000h mark. It will take some time before enough data can support such claims. Also, most installations to date have been radically different so it would be hard to draw conclusions. Most failures to date have not been with the core engine but alternators, coolant leaks, oil leaks, exhaust failures...lots of details can bring you down and liquid cooled wankels have more details.
I am also somewhat concerned lately about new products such after market cermet/whatever seals and coatings. Particularly, when few details are published on specs, testing,...they may in fact be great. It is annoying when your engine pops in a car, it really sucks over buildings, trees, rocks, water in a plane.
As an additional note, all engines have resonances and torsional resonances. Note that some certified aircraft have no fly engine/prop combinations. These can cause premature catastrophic fatigue failure in the prop, prop shaft, crank, eshaft(ok, not yet), redrive.... Tracy Crooks' damper appears to have dealt with them rather well, I assume the other vendors have dampers as well.
With regards homebuilts vs certified, I always joke than I don't feel comfortable in an airplane that is younger than me...
I am just as interested in who built a homebuilt as I am in the maintainer of a certified aircraft before I get in it. I have seen more problems (read there is usually something broken) with rental aircraft than homebuilts...
RVs and Lancairs (...) also look cooler, fly faster and cost way less...
Another opinion
Cheers
Cary
08-25-06, 03:33 PM
#34
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The cubs were originaly armed with a c65, people then put c85 in them. A comon mod for the cub is to install a Lycoming 0-200, or 0-230. The dry weight of the 0-230 is 220lbs, and they run between 100-130hp.
So a 12a with 130hp is easy to make, and the installed weight will be lsigtly heavier. I estamate 20lbs. I emailed one of the aviation rotary builders ( real world solution inc.) and have not gotten a responce back lol.
So a 12a with 130hp is easy to make, and the installed weight will be lsigtly heavier. I estamate 20lbs. I emailed one of the aviation rotary builders ( real world solution inc.) and have not gotten a responce back lol.
08-25-06, 09:12 PM
#35
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They use them for R/C Model Airplanes
They also use them in R/C model airplanes. If I ever get a chance to buy one for R/C I would love to try it in one of my Models.
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08-25-06, 09:48 PM
#36
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Originally Posted by trydis7
The aviator makes a lot of valid points.
Wankel engines are a valid alternative to traditional aircraft engines, however, an auto conversion is a LOT of work and you or whoever does the conversion has a lot of homework to do (guess how I found out?) to get it right.
Certified aircooled engines have several advantages. The larger displacement (say O -320 cubic inch) allows a simple engine to produce 150hp at a relatively low 2700rpm direct drive relatively reliably for 2000?hours or so. This same engine converted to auto use could probably pump out 300+hp peak less reliably. The engine is also air cooled which has the advantage of simplicity and disadvantages such as shock cooling.
The major advantage of certified engines is the fact they have been around soo long (50+ years) that most of major bugs have been worked out and many people know about them. The fact that few engines will make it to the 2000 hour TBO with original components (read cylinder, crank,... problems) does not seem to bother most people. Buying a used aircraft engine is riskier than buying a used car from a used car salesman with all of the lightly used/maintained aircraft around.
The wankel is a cheap alternative that can reliably deliver a higher power to weight than certified engines at a higher rpm as witnessed by Tracy Crook, Atkins and others. It does mean that YOU have to pioneer and work out all of the bugs before they succeed in trying to kill you. Fortunately many groups are exchanging knowledge and best practices. There are also pioneering outfits out there such as Tracy Crook (rotary aviation, with a name like that you gotta be doubly honest and he is), Powersport, Mistral and Atkins who have done research, design and testing. You would be wise to join some of the online groups, copy a proven installation and purchase products from some of thse companies or be prepared to do a lot of test/piloting.
The wankel also offers better failure modes that aircooled engines, however, the reality is few(2500h gyro?) have yet made the magical 2000h mark. It will take some time before enough data can support such claims. Also, most installations to date have been radically different so it would be hard to draw conclusions. Most failures to date have not been with the core engine but alternators, coolant leaks, oil leaks, exhaust failures...lots of details can bring you down and liquid cooled wankels have more details.
I am also somewhat concerned lately about new products such after market cermet/whatever seals and coatings. Particularly, when few details are published on specs, testing,...they may in fact be great. It is annoying when your engine pops in a car, it really sucks over buildings, trees, rocks, water in a plane.
As an additional note, all engines have resonances and torsional resonances. Note that some certified aircraft have no fly engine/prop combinations. These can cause premature catastrophic fatigue failure in the prop, prop shaft, crank, eshaft(ok, not yet), redrive.... Tracy Crooks' damper appears to have dealt with them rather well, I assume the other vendors have dampers as well.
With regards homebuilts vs certified, I always joke than I don't feel comfortable in an airplane that is younger than me...
I am just as interested in who built a homebuilt as I am in the maintainer of a certified aircraft before I get in it. I have seen more problems (read there is usually something broken) with rental aircraft than homebuilts...
RVs and Lancairs (...) also look cooler, fly faster and cost way less...
Another opinion
Cheers
Cary
makes a lot of valid points.Wankel engines are a valid alternative to traditional aircraft engines, however, an auto conversion is a LOT of work and you or whoever does the conversion has a lot of homework to do (guess how I found out?) to get it right.
Certified aircooled engines have several advantages. The larger displacement (say O -320 cubic inch) allows a simple engine to produce 150hp at a relatively low 2700rpm direct drive relatively reliably for 2000?hours or so. This same engine converted to auto use could probably pump out 300+hp peak less reliably. The engine is also air cooled which has the advantage of simplicity and disadvantages such as shock cooling.
The major advantage of certified engines is the fact they have been around soo long (50+ years) that most of major bugs have been worked out and many people know about them. The fact that few engines will make it to the 2000 hour TBO with original components (read cylinder, crank,... problems) does not seem to bother most people. Buying a used aircraft engine is riskier than buying a used car from a used car salesman with all of the lightly used/maintained aircraft around.
The wankel is a cheap alternative that can reliably deliver a higher power to weight than certified engines at a higher rpm as witnessed by Tracy Crook, Atkins and others. It does mean that YOU have to pioneer and work out all of the bugs before they succeed in trying to kill you. Fortunately many groups are exchanging knowledge and best practices. There are also pioneering outfits out there such as Tracy Crook (rotary aviation, with a name like that you gotta be doubly honest and he is), Powersport, Mistral and Atkins who have done research, design and testing. You would be wise to join some of the online groups, copy a proven installation and purchase products from some of thse companies or be prepared to do a lot of test/piloting.
The wankel also offers better failure modes that aircooled engines, however, the reality is few(2500h gyro?) have yet made the magical 2000h mark. It will take some time before enough data can support such claims. Also, most installations to date have been radically different so it would be hard to draw conclusions. Most failures to date have not been with the core engine but alternators, coolant leaks, oil leaks, exhaust failures...lots of details can bring you down and liquid cooled wankels have more details.
I am also somewhat concerned lately about new products such after market cermet/whatever seals and coatings. Particularly, when few details are published on specs, testing,...they may in fact be great. It is annoying when your engine pops in a car, it really sucks over buildings, trees, rocks, water in a plane.
As an additional note, all engines have resonances and torsional resonances. Note that some certified aircraft have no fly engine/prop combinations. These can cause premature catastrophic fatigue failure in the prop, prop shaft, crank, eshaft(ok, not yet), redrive.... Tracy Crooks' damper appears to have dealt with them rather well, I assume the other vendors have dampers as well.
With regards homebuilts vs certified, I always joke than I don't feel comfortable in an airplane that is younger than me...
I am just as interested in who built a homebuilt as I am in the maintainer of a certified aircraft before I get in it. I have seen more problems (read there is usually something broken) with rental aircraft than homebuilts...
RVs and Lancairs (...) also look cooler, fly faster and cost way less...
Another opinion
Cheers
Cary
Even with the availability of bolt-on redrive, engine mounts, ignition controllers and other components that are being supplied by Tracy and others there is still extra work to do to get the powerplant installed and properly tuned.
I would also add that the jury is still out with regard to the question of resale value of a quality auto conversion aircraft vs. the same plane with a rebuilt Lycosaurus.
Still, I'd rather fly behind a rotary than behind an over-priced, over-rated (especially in the reliability department) and outdated boinger any day.
As for projected TBO, there is a reason only a very few rotaries (and only one that I'm aware of, the afore-mentioned 2500 hours accumulated by Jim Mayfield in one of his gyrocopters) have topped 2000 hours--- it takes a long-*** time for most of us to accumulate that many hours, anywhere between ten and twenty years.
But while piston auto engines seem to be throwing rods and swallowing valves like clockwork around the three-to-five hundred hour mark, rotaries seem to be brought down prematurely by only three things: no fuel, no fire, or ingestion of large foreign objects--- none of which has any relevance to the durability and wear characteristics of the engine type.
Speaking of which, the certified aircraft piston engines quite often do not make it to TBO without a top overhaul, even when properly maintained. In fact, some don't even have a TBO of more than 1500 hours--- pretty unacceptable for an engine that sells (rebuilt, not new) for somewhere north of 40k...
Btw, Cary--- would it be correct to assume you have built (or are currently building) a plane? If so, which one?
Last edited by Aviator 902S; 08-25-06 at 10:03 PM.
08-25-06, 11:31 PM
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Originally Posted by Aviator 902S
This pretty much sums up everything I was too lazy to type out.
Even with the availability of bolt-on redrive, engine mounts, ignition controllers and other components that are being supplied by Tracy and others there is still extra work to do to get the powerplant installed and properly tuned.
I would also add that the jury is still out with regard to the question of resale value of a quality auto conversion aircraft vs. the same plane with a rebuilt Lycosaurus.
Still, I'd rather fly behind a rotary than behind an over-priced, over-rated (especially in the reliability department) and outdated boinger any day.
As for projected TBO, there is a reason only a very few rotaries (and only one that I'm aware of, the afore-mentioned 2500 hours accumulated by Jim Mayfield in one of his gyrocopters) have topped 2000 hours--- it takes a long-*** time for most of us to accumulate that many hours, anywhere between ten and twenty years.
But while piston auto engines seem to be throwing rods and swallowing valves like clockwork around the three-to-five hundred hour mark, rotaries seem to be brought down prematurely by only three things: no fuel, no fire, or ingestion of large foreign objects--- none of which has any relevance to the durability and wear characteristics of the engine type.
Speaking of which, the certified aircraft piston engines quite often do not make it to TBO without a top overhaul, even when properly maintained. In fact, some don't even have a TBO of more than 1500 hours--- pretty unacceptable for an engine that sells (rebuilt, not new) for somewhere north of 40k...
Btw, Cary--- would it be correct to assume you have built (or are currently building) a plane? If so, which one?
Even with the availability of bolt-on redrive, engine mounts, ignition controllers and other components that are being supplied by Tracy and others there is still extra work to do to get the powerplant installed and properly tuned.
I would also add that the jury is still out with regard to the question of resale value of a quality auto conversion aircraft vs. the same plane with a rebuilt Lycosaurus.
Still, I'd rather fly behind a rotary than behind an over-priced, over-rated (especially in the reliability department) and outdated boinger any day.
As for projected TBO, there is a reason only a very few rotaries (and only one that I'm aware of, the afore-mentioned 2500 hours accumulated by Jim Mayfield in one of his gyrocopters) have topped 2000 hours--- it takes a long-*** time for most of us to accumulate that many hours, anywhere between ten and twenty years.
But while piston auto engines seem to be throwing rods and swallowing valves like clockwork around the three-to-five hundred hour mark, rotaries seem to be brought down prematurely by only three things: no fuel, no fire, or ingestion of large foreign objects--- none of which has any relevance to the durability and wear characteristics of the engine type.
Speaking of which, the certified aircraft piston engines quite often do not make it to TBO without a top overhaul, even when properly maintained. In fact, some don't even have a TBO of more than 1500 hours--- pretty unacceptable for an engine that sells (rebuilt, not new) for somewhere north of 40k...
Btw, Cary--- would it be correct to assume you have built (or are currently building) a plane? If so, which one?
I have helped on several homebuilt, rebuild, engine, custom redrive, tortional damper projects - good way to learn. I have a super secret one-off project in the works with, guess what? a rotary engine.
Cheers
08-26-06, 01:54 AM
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Originally Posted by doridori-rx7
this sounds pretty typical of most 'cert or nothing people' ,
Thier is a difference between a pistion and rotary ' auto conversion' this should be glaringly evident in the countless hrs logged by the rotory and subsequent teardowns that show no wear.
larger displacement? low rpm tq? i't scalled a reduction gear.. any motor can be put into the right powerband / prop speed with one. Your argument is the smae one the V8 conversion guys use for thier need to do a swap.. they want the low end tq... for what? pulling a boat? your aircraft pulling a boat and you don't have access to a reduction gear.. that argument is flawed on our part.
thier is no advantage your using a motor that is 50 years old and for legal reasons they can't upgrade.. everything HAS to be made to the specs of 50 years ago or more.. which meants the typical head cracks on the conti will contine. By your reasoning you might as well go back to using a flathead ford or stove pipe six , since naything newer is not 50 years old.. So your'll stick to outdated technology, serviced by people who make a fortune off the serviceing and parts companies that make an even bigger fortune off the purchase of parts for those servicing.. yeah I can see why the promotion of 'new' is not pushed you guys are suckers.
Pioneer?? where do you get this , thier are 1000's of flying hrs on these motors now. In all sorts of aircraft doing all sorts of jobs.. thier is no pioneering left it's simply refinement and improving design .. this is something that can never be done with a certified engine.
Failures have been almost solely due to home built installations and the people having no clue how to do a proper firewall forward package nor how to build or spec the proper materials for the buld of a rotary always ON power.
Thier is a difference between a pistion and rotary ' auto conversion' this should be glaringly evident in the countless hrs logged by the rotory and subsequent teardowns that show no wear.
larger displacement? low rpm tq? i't scalled a reduction gear.. any motor can be put into the right powerband / prop speed with one. Your argument is the smae one the V8 conversion guys use for thier need to do a swap.. they want the low end tq... for what? pulling a boat? your aircraft pulling a boat and you don't have access to a reduction gear.. that argument is flawed on our part.
thier is no advantage your using a motor that is 50 years old and for legal reasons they can't upgrade.. everything HAS to be made to the specs of 50 years ago or more.. which meants the typical head cracks on the conti will contine. By your reasoning you might as well go back to using a flathead ford or stove pipe six , since naything newer is not 50 years old.. So your'll stick to outdated technology, serviced by people who make a fortune off the serviceing and parts companies that make an even bigger fortune off the purchase of parts for those servicing.. yeah I can see why the promotion of 'new' is not pushed you guys are suckers.
Pioneer?? where do you get this , thier are 1000's of flying hrs on these motors now. In all sorts of aircraft doing all sorts of jobs.. thier is no pioneering left it's simply refinement and improving design .. this is something that can never be done with a certified engine.
Failures have been almost solely due to home built installations and the people having no clue how to do a proper firewall forward package nor how to build or spec the proper materials for the buld of a rotary always ON power.
It is an excellent engine and it's use is gaining momentum. It has advantages and disadvantages like everything else. I am trying to present it honestly, worts and all.
The lack of a reduction gear means one less thing to fail...and there have been redrive failures, mostly the old ross redrives without an anti-thrust bearing or after Lou Ross? The latest generations seem to be rock-solid, but again time will tell. You might also note that some LS1 installations don't quote an rpm anywhere near their top end? (plus an odd 1.3 reduction to boot?, why bother?)
I have seen several pictures in the last year of rotor housings, using aftermarket seals, some just a few days ago on http://www.rotaryeng.net/, that showed very premature signs of wear...I don't know what to think?
I agree with you - certified=expensive/fixed=lack of innovation= opportunity for the rotary and other piston engines.
And you reinforce my point that bolt-on packages from the pioneers - Tracy, Ray/EverettHatch/Powersport, Francois/Gordon/Mistral, Dave/Atkins are the way to go.
Yes there are thousands of rotary flight hours, just not a lot of high timers (yet). I am aware of one(1) 2500h gyro, Tracy Crook is #2? at what? 1500? hours. Not sure if any early (record setting) powersport installs are higher. I call that excellent compared to most certified engines, given its HP and cost advantages.
There is still plenty of innovation that can take place - reduced weight(more AL/ceramic), proven seals/coatings, pport. Dreams of exotic/ceramic rotors and stupidly high rpm/hp? Intake, exhaust and cooling installations are high runners.
Paul Lamar's turbo compound http://www.rotaryeng.net/ looks promising for reduced fuel consumption- he seems to have re-ignited research in the field.
Published dyno time of installations would help - I would love to see a few dyno results of certified installations (whose HP is optimistic before exhaust losses, there is HUGE variations between specific engine/installations). Did you see the protoype adjustable telescopic trombone intake I threw together? rough, but good enough for dyno data points.
You are right about the homebuilt installations - most people are doing it themselves, with the help of the online newsgroups and best practices. although there is still a lot of disagreement on some things - interestingly, many diametrical installations are flying
You seem to be very knowledgeable and opinionated. I would be interested in dropping by your shops or discuss stuff over a beer.
A business opportunity for you might be to put together an RV installation for a customer, dyno it and offer it as a product.
Cheers
08-27-06, 11:08 AM
#39
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I'll take a reduction gear over a valve train anyday... Also we've got a few designs comming along for a variable pitch, reduction gear setup for the rotary at the moment..
The bulk of rotary homebuilt failures I've seen/heard mention of are due to the poor installs and subsystem setups. I can think of a few from the ACRE NL, that fit that bill in the last year alone.
And we do have a firewall FWD setup for our aircraft.. but no one has ever aproached us for an RV4 install yet.
The bulk of rotary homebuilt failures I've seen/heard mention of are due to the poor installs and subsystem setups. I can think of a few from the ACRE NL, that fit that bill in the last year alone.
And we do have a firewall FWD setup for our aircraft.. but no one has ever aproached us for an RV4 install yet.
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