Eggenfellner West

[rv6ejguy]

Actually if you look back through this thead and others, others have stated that Subaru engines have suffered many bottom end failures. When I asked for the details, as usual, none came forth from these people because it is simply not true. For anyone to make comments that Subaru bottom ends are weak is simply unsubstantiated nonsense. If anything, relatively speaking about specific output, the Lycoming bottom end is nowhere near as strong as a Subaru. Not that this matters in a 180hp aircraft application where both have proven quite reliable. The fact that the Sube can withstand a specific output over over 380BHP/ L for a few minutes even attests to it's strength.

My comment about Lyco cranks was referring to the massive number affected by ADs and SBs over the last 6 years. We are talking THOUSANDS of cranks, dozens of failures and 2 major lawsuits. To say that this is a minor problem is bizarre.

Lyco's head does not think this is a minor problem nor does parent Textron which is why they hired him.

I've never said that Lycos are junk. Use 'em if you like 'em. I think many dyed in the wool Lyco fans find the string of crank ADs hard to swallow when they have to foot the bill and are looking at other alternatives. It's as simple as that. Let them look. They may or may not buy once they check it out but it will be their decision based on their likes, dislikes and mission priorities, not yours.

The comment that pre 1990 cranks are good implies that you recognize that the late manufacture stuff is not so good.

As someone who has worked on and flown both Lyco powered and Subaru powered aircraft and building peformance engines for nearly 30 years, I understand the advantages and disadvantages of both possibly more than most. I think I sum the concerns up fairly in my Kitplanes article. Many people who know me thought the article might be like so many others on auto engines- being lighter, cheaper, smoother, faster and burning less fuel. My testing showed that many of these things were simply not true and I reported it that way.



Eggenfellner is addressing fuel burn and cooling drag issues with new parts for the new H6 installations like the James cowlings and other hardware under test right now.

 

[gmcjetpilot]

My comment about Lyco cranks was referring to the massive number affected by ADs and SBs over the last 6 years. We are talking THOUSANDS of cranks, dozens of failures and 2 major lawsuits. To say that this is a minor problem is bizarre.

Lyco's head does not think this is a minor problem nor does parent Textron which is why they hired him.

Oh no this is an ugly ugly mess. I am not affect or named in the law suit. However I agree they have problems getting good forgings. Many years ago it was materials. Than it was process control and inspection. I don't get it. The crank is the critical component. I am not happy or defending this. I have been around major engineer boo boo's. I was called in after the fact. The last time was stingers on the wing of large jet. They where not properly shot peen-ed for fatigue improvement and installed on the wing panels. Analysis could not show it good as is. Also scraping 10 mil worth of wing panels was no good either. So the stringers where removed and new ones installed. This created problems as many holes had to be reworked, for the inevitable damage that occurred during fastener removal and re-installation. How the parts got onto the wing in the first place I don't know.

I know. It is a mess. I reviewed the "customer letter", AD and SB. I am not on the list since my crank was made in the late 70's or early 80's. When I took my Lyc apart it had 600 hours on the second overhaul. It was like new. I lucked out. I'll give no argument defending Lycs on this issue, BUT if they are built to specs (which millions have been), thankfully, flown and maintained properly, it is not an issue for operators. On one hand Lycoming stood up to the plate, on the other they are only offering replacement parts for $2000 and no labor. Also they somehow did not communicate with the forging manufacture, which just won against Lycoming claims they where responsible. Ugly Ugly mess I agree, but still this is a blip on an otherwise excellent record.

Cheers George

PS: I WOULD LOVE to read your article in kit plane, any chance you have a scan copy you could send me? [email protected]. If you do I promise not to post on alternative engines for a week!

 

[rv6ejguy]

I have little doubt that Lycos and the clones will continue to equip the majority of new RVs for at least the next 5 years and maybe more. The auto engines are being chosen by more builders every year, percentage wise. I can only guess that not all these people are fools and have their own good reasons for choosing an auto engine. No doubt some regret the choice. Most seem happy with them. We're seeing a massive increase in interest over the last 2 years in the Suzuki G10 and G13/G16 engines as Rotax alternatives also.

Eggenfellner has made the Subaru conversions as painless as possible and continues to improve his units. The engine arrives in the crate attached to the mount, with redrive and all accessories attached. You simply bolt it up to the firewall and install the wiring, cables etc. Initial price is not the advantage of these engines but the users wax poetic generally on how much they enjoy flying them and flying is what we all like to do. Matters not what is turning the fan too much as long as it is reliable.

The unabridged Kitplanes article can be read here: http://www.sdsefi.com/air43.htm sans photos

There are some more photos and test data here: http://www.sdsefi.com/rv14.htm

Point of interest, I think Lyco has built around 40,000 opposed piston aircraft engines not millions. If someone has a more accurate number, please correct me.

 

[ship]

if they are built to specs (which millions have been),

therein lies the problem: "if" and "millions". Lyco has a lot of "if" and they probably haven't made a million cranks, let alone engines. Not even close.

Lycomings problems started when they began outsourcing the manufacture of the cranks.

Aviation is a flyspeck in the manufacturing arena. Quality control is very difficult when there are no economies of scale, especially in complex forgings. Crankshafts are by FAR the most complex piece of a Lycoming. Only 2 US companies are qualified to manufacture aviation crankshafts.

Lycoming has made a TOTAL of approx. 350,000 engines since 1938.

Toyota makes more engines in 2 weeks than Lyco has made in it's entire 68 year history.

Think about that for a second. 2 weeks vs. 68 years.

Put another way, Lycoming will finish making a SINGLE year's worth of Toyota engines in the year 3706.

Put another way, to "finish" this year, they needed to start production in the year 300 AD. (some people swear that's the date of the last Lyco design update )

Put another way, Toyota makes a year's worth of Lycoming production in a SINGLE 8-hour shift.

Subie makes 350,000 engines every 6 months.

Lyco is literally a grain of sand on a beach. Even so, there is no excuse for the crank problems. None.

 

[ship]

The unabridged Kitplanes article can be read here: http://www.sdsefi.com/air43.htm sans photos

excellent article.

Ross hits on a major item. Putting radiators in an airplane is like opening a barn door in a hurricane, i.e. be prepared for some s-e-r-i-o-u-s drag along with weight and hair-pulling design issues. Especially when the prop is up front.

if anyone is interested in understanding the ENORMOUS challenges in designing low-drag liquid-cooling systems for aircraft, this link is the best I've seen yet at laying out the subject. http://www.rotaryeng.net/how-to-cool12.html It's an eye-glazer but you'll get the gist. Written for rotary conversion but applicable to all liquid engines in aircraft.

 

[gmcjetpilot]

Oh my! logical fallacies

therein lies the problem: "if" and "millions". Lyco has a
lot of "if" and they probably haven't made a million cranks, let alone
engines. Not even close.

Lycomings problems started when they began outsourcing the manufacture
of the cranks.

Aviation is a flyspeck in the manufacturing arena. Quality control is very
difficult when there are no economies of scale, especially in complex
forgings. Crankshafts are by FAR the most complex piece of a Lycoming.
Only 2 US companies are qualified to manufacture aviation crankshafts.

Lycoming has made a TOTAL of approx. 350,000 engines since 1938.

Toyota makes more engines in 2 weeks than Lyco has made in
it's entire 68 year history.

Think about that for a second. 2 weeks vs. 68 years.

Put another way, Lycoming will finish making a SINGLE year's worth of
Toyota engines in the year 3706.

Put another way, to "finish" this year, they needed to start production in the
year 300 AD. (some people swear that's the date of the last Lyco design
update )

Put another way, Toyota makes a year's worth of Lycoming production in a
SINGLE 8-hour shift.

Subie makes 350,000 engines every 6 months.

Lyco is literally a grain of sand on a beach. Even so, there is no excuse for
the crank problems. None.

First I stand corrected, Lycomings aircraft engines dates to the early 1920s,
when it produced a nine-cylinder radial, the R-680. I have no idea, but
current estimate of Lycoming's in service TODAY is about 90,000. I
concede that there where not millions built, I don't know how many where
built? This was an honest mistake, but at least I don't have a fallacy of
logic.

I agree there are no excuses for crank problems.

My comment about production volumn, to you, is so what?

Low production should mean better QC and control not worse.

Can't auto engine adaptation into planes stand on their own merit?

Its like politics. no position or defense so attack opponent.

Its like the RV "A" models that have flipped. Some get defensive and say
the tail draggers flip to. Fair enough but that does nothing to address the
issues of how and why the "A" model flips.

Production volumn is a BIG fat Non sequitur's. (Latin for Informal logic, an
argument is a non sequitur if the conclusion does not follow from the premise.
A non sequitur, the conclusion can be either true or false, but the argument
is a fallacy because the conclusion does not follow from the premise. It is
fallacy of logic. Statistics point to more units = more chance for failure.)
So I agree there is no excuse, especially Lyc, ECI or superior.

Who cares about how many car engines Toyota makes? What is the point.

Lycoming does not make a good engine because Toyota makes lots of
them (for cars)? Does not compute. With that logic, Toyota makes a
lot more Corolla's than RV-4/6/7/8/9/10's so a Toyota should fly better
than a RV?

Fun fact: There are almost 100,000 Lycoming engines in SERVICE,
today. About 121,200 on FAA reg. Continental about the same.
World wide who knows. The combine total of all air cooled piston
engines on FAA books, almost a 1/4 Mil (including Franklin, P&W, Wright).
I am going on a limb and going to say it is a few more than Subaru and
Mazda? Could be wrong, lol. Than again it does not matter.

Is this "scale of production" an argument about how expensive Lycoming
is? Because the auto guys have lost that. I can buy a brand new O360 for
less than $20,000. I have $12K into my overhauled O360 with dual
electronic ignition. The price of "Lycomings" have gone down with now
three manufactures (Lyc, ECI, Superior). That is economy of scale.


I don't think there is any doubt that Lycoming has an excellent reputation,
at least to me. A quote from Lycoming:
Did this reputation for reliability just happen?
No, it is the result of more than 60 years of experience with aircraft
engines. That does not mean that the same individuals who engineered the
Lycoming engines of the 1930s and 1940s are still at Lycoming. It does
mean that their experience has been passed on. What has been learned from
thousands and thousands of hours of test-stand running and engineering
flight tests over all of those years provides a solid data base of knowledge
which is used to insure that a certified Lycoming engine is a safe and
reliable device when operated and maintained as recommended by the
manufacturer.


Stick to the issues. Who cares how many are built? Not sure where your
numbers are from, but please post your references and sources. I'll try to
do the same, but it does not matter how many engines are made. No
offense. I want to hear how you are going to make your car engine
lighter, cheaper, faster. Forget Lycoming

"Ship", you are forgiven, because of the excellent refrence to "How to
cool your Wankel". That is what I am talking about. Just slapping a heat
exchanger in willy-nilly won't work (well). The issue is airframes, like the
RV are so compact that installing radiators is HARD. That is why air
cooled is SO nice and why I went that way. That whole article begs
to ask the question, why not air cooled? Why not. The installation is
easy. Until engine, airframe and installation come together as an
integral system working in concert, water cooled engines (any) will
not work to the full potential (well). I was surprised that he felt the
P-51 could be improved. Excellent bring it on.

After the cooling drag issue is the prop. Hydraulic props are a better
system. Electric props have been done, 1942 Curtiss C-46 Commando
to Beechcraft Bonanza w/ electric beech prop. There are all gone in
favor for hydraulics. Not to mention you are limited to MT or IVO props.
Not that MT is bad, their FAT/THICK arirfoil, wood/fiberglass blades are
just not quite efficient and they cost too much.

George

PS:
Prediction, auto engine adaptations will never be the most popular engine
in aircraft, specifically RV's. I don't say this to be mean, I say this as a
challenge. Enough talk and excuses and pointing at Lycoming's small
productions, get with it. Prove me wrong. Auto engines will not be
popular unless their performance, weight, cost and installation all
balance out. Right now Lycoming is the winner in every category.
Forget Crank AD's. The statistics of a crank failure are such you likely
have a better chance of the wing coming off or your Subaru's ECU
going HAL 9000 (2001 space odyssey refrence) before a Lyc crank.

The Rotax is not a great engine from what I hear, but we are talking
about an expensive small 81 HP engine. I have no refrence for that
except second hand comments about cost and TBO issues.

If you want water cooled here you go:
http://www.liquidcooledairpower.com/ss-main.shtml
http://www.liquidcooledairpower.com/cj-overview.shtml
http://www.liquidcooledairpower.com/images/ad_cooljugs.jpg
http://www.liquidcooledairpower.com/gallery/view_album.php?set_albumName=cherokee-conversion
CHECK THESE PICTURES (link above) GREAT IDEAS HINT HINT

 

[rv6ejguy]

excellent article.

Ross hits on a major item. Putting radiators in an airplane is like opening a barn door in a hurricane, i.e. be prepared for some s-e-r-i-o-u-s drag along with weight and hair-pulling design issues. Especially when the prop is up front.

if anyone is interested in understanding the ENORMOUS challenges in designing low-drag liquid-cooling systems for aircraft, this link is the best I've seen yet at laying out the subject. http://www.rotaryeng.net/how-to-cool12.html It's an eye-glazer but you'll get the gist. Written for rotary conversion but applicable to all liquid engines in aircraft.

Unfortunately Paul Lamar's piece here is full of assumptions and non-flight proven conjecture not to mention many conclusions which are simply incorrect. Paul has never flown any of his ideas. I always find it interesting when "experts" poke fun at a proven system like the P51 rad setup. Over 20,000 examples flying, properly cooling a 2 stage supercharged 1700hp engine up to 35,000 feet and still being used in one form or another on 500mph Reno racers. Show me one experimental liquid cooled installation which has achieved anywhere close to this performance. The people who designed this setup were way more knowledgeable than we ever will be about this stuff. People incorrectly assume that a boundary layer rad scoop will offer higher drag than an obliquely mounted simply because there is more frontal area and wetted area. The internal aerodynamics of any duct/ heat exchanger design primarily determine pressure drop and drag.

Rads mounted oblique to the airflow are a bad idea from a drag point of view without doubt. Anytime you turn air 45 or 90 degrees from its direction of travel, you have losses and turbulence. Even wonder why no successful WWII liquid cooled aircraft had obliquely mounted rads? These people were not stupid. Although aircraft like Strega and Voodoo have reshaped the duct, they have not laid the rads down. I've met these people. They are very smart and certainly don't do things to make the aircraft slower.

I have copies of the P51 maintenance manuals with regards to the cooling system and it is facinating reading. When I built my 6A I thought all these other guys were dumber than me when it came to cooling problems. I was wrong about that! Until you've actually done this successfully, my advice is to keep quiet. It is harder than it looks.


Learn from history or you are destined to repeat its mistakes.

 

[cjensen]

If you want water cooled here you go:
http://www.liquidcooledairpower.com/ss-main.shtml
http://www.liquidcooledairpower.com/cj-overview.shtml
http://www.liquidcooledairpower.com/images/ad_cooljugs.jpg
http://www.liquidcooledairpower.com/gallery/view_album.php?set_albumName=cherokee-conversion
CHECK THESE PICTURES (link above) GREAT IDEAS HINT HINT

i've been watching these cool jugs guys for a long time now. i think this is a GREAT idea for lyc's and clones!

 

[gmcjetpilot]

Article, P-51 and P-38

Unfortunately Paul Lamar's piece here is full of assumptions and non-flight proven conjecture not to mention many conclusions which are simply incorrect. Paul has never flown any of his ideas............ The internal aerodynamics of any duct/ heat exchanger design primarily determine pressure drop and drag.

Rads mounted oblique to the airflow are a bad idea from a drag point of view without doubt. Anytime you turn air 45 or 90 degrees from its direction of travel, you have losses and turbulence.

I have copies of the P51 maintenance manuals with regards to the cooling system and it is fascinating reading. When I built my 6A I thought all these other guys were dumber than me when it came to cooling problems. I was wrong about that! Until you've actually done this successfully, my advice is to keep quiet. It is harder than it looks.

Right on. I liked the article. I only gave it the Evelyn Wood's speed reading treatment (which does not work for technical articles), but thought it made some good points.


However I was surprised when he took on the P-51 belly scoop. As you point out there have been small changes made to it by P-51 Reno racers, but almost everything you want to know about the engineering and aerodynamics of subsonic cooling / heat exchangers has been known since the 40's. Yes there has been advancements, but very small ones. I have looked at the NASA (than NACA) top secret reports (now declassified) on the design. Amazing. Than jets happened. Most heat exchanger research is now for supersonic work. The B767 I fly has skin heat exchangers to cool the avionics. No ducts or openings to the outside. It only works when flying at altitude. On the ground vents open in the belly and a fan or differential pressure is used to flow air for cooling.


They did know what they where doing. I am not saying there is not another way, but as you point out turning air 90 degrees and than trying to reintroduce that air back into the free airstream at 90 degrees is draggy. However he does outline the challenges. I don't think modification of the center section belly, aft wing spar, would be a big issue. Custom heat exchangers I suppose can be made to allow more off angle airflow for horz rads, but most Rads require the air to go thru at perpendicular.


He goes on and name drops Kuchemann & Weber (B-36) and Kays & London wedge shaped diffusers, while making some negative comment about the "7-degree rule" which is a good number for straight sides. However curved shapes and multi flow dividers/guides can message the air into submission. However I am with you rv6ejguy, it's all great on paper, but putting it into practice is another issue. I have a copy of the dictionary with all the English words, but that does not mean I can write a best selling novel. Adapting, designing, sizing and installation is the challenge. As I said there is room for improvement to the existing standard (Eggy). However to be fair to Eggenfellner, if you want a drop in stand alone self contained solution that is about as good as it gets. If you want something more elegant, than it will take an integrated airframe approach.

I really like what cool jug did, but it is a compromise. However it keeps it all under the cowl, which is a hard trick to pull off. I am guessing that cool jugs approach is half the drag as Eggenfellenrs standard approach, but still more than an optimal air cooled installation (aka Sam James style, pressure plenum). The Cool Jug set-up, likely more total drag than a "Sam James" set up, is no doubt way better than a stock Piper set up. It is not all bad, and compromises have to be made sometimes. They (cool jugs) recognises that just making a water cooled engine will not lead them to riches unless a matching installation is provided. That is where Mistral needs to go with their Rotary engine. They need a FWF installation for each airframe. That is the hard part. An engine on a dyno impresses me not. At least Powersport (the other FWF rotary kit) did this right. They offer the whole deal, cowl, installation and engine. However with that said getting a optimal water cooled installation all stuffed into the cowl is probably not physically possible. The Rad's need to be integrated into the airframe and that does not fit the BOLT it up aircooled engine replacement concept some sales folks promote.


Selected pictures of "cool jugs" cooling Rad and cowl:
http://www.liquidcooledairpower.com/albums/radiator/167_6723_IMG.sized.jpg
http://www.liquidcooledairpower.com/albums/radiator/IMG_9736.sized.jpg
http://www.liquidcooledairpower.com/albums/cowling/154_5448_IMG.sized.jpg
http://www.liquidcooledairpower.com/albums/engine-install/IMG_9731.sized.jpg
http://www.liquidcooledairpower.com/albums/cowling/156_5666_IMG.sized.jpg


The P-38 (lightning) had 4-boom mounted heat exchangers did it not?

Interesting the P-38 used wing leading edge intercoolers to cool the supercharged induction air. This link discusses but nothing about the water cooling heat exchangers on the side of the booms:
http://p-38online.com/p38j.html

What about a side scoop for the RV? It could be dual symmetric or single asymmetric. The radiator inside the aft fuselage (vertical and and vented out the belly). I think you tried this rv6ejguy, did you not.

Here are some wild guesses (feel free to criticize, they are just swags):


Anyway you guys keep at it, looking forward to cool stuff in the future. Hope this gets some creative juices flowing. If it was easy everyone would have done it. It is too much for me, so I will take the a position in the peanut gallery as self appointed "expert".

George

 

[avaviat]

Regarding the quantity sequitur...

If you take the statistical view of QA, production quantity matters. When 1,000,000 engines of a particular type are produced in a given year, you can easily find out if there is a 0.001% failure rate....that's 1000 failures. If you have 1,000 crank shaft failures, you have a 0.001% crank shaft failure rate +/- some small amount. If, otoh, 5,000 are produced per year, you simply can't compute such a failure rate accurately...after all, it would only be 5 failures, and five failures may not even indicate a trend. It is almost impossible to do statistical QA on small production runs. Sampling 1 in 10 becomes worthless if you are only producing 10 units. You simply can't claim to produce 99.9999% good engines if you only produce 1000 engines a year.

My view...

1) Engineering is all bean counting. It is all about minimizing the cost of obtaining a target performance. That's why overengineering is so common.

2) The word "Overengineering" does not mean what most people think it means. Most people think overengineering is a synonym for "making something stronger than it needs to be", but in truth it means "making something that does exactly what is specified with no margin (that costs anything), and if possible making one item do several jobs to reduce the overall cost."

3) Auto makers employ many engineers.

That is what makes me mistrust auto conversions... the knowledge that any decent engineer will tailor their product to the stresses it should actually see. Someone designing a car engine can legitimately say "I control the ECU, I control the transmission, I control everything... and I can sense knocking, sense temperatures, sense enough that if some damned fool keeps his foot on the gas when she shouldn't, I'll back off enough to keep the conrods from folding." When you attempt to engineer another product (aircraft propulsion system) based on that product, you must esentially reverse engineer the design constraints so you can decide whether their product can meet your needs. Auto makers constantly refine their engines, and not all of the refinements are across-the-board improvements. It may be a real and significant improvement to them, but that improvement might make it a worse engine for a different task.

OTOH #1) Many engine manufacturers want to sell a single product to multiple markets or use it in a variety of vehicles. E.g. GM uses the same basic engine in small cars and relatively much larger pickup trucks; VW sells the same engine in a car and as an industrial engine for running gensets and the like. As such they may not overengineer as much as they could.

OTOH #2) Sometimes, in order for something to work at all it must work very well. I own a VW TDI... which normally runs ~26"hg manifold pressure...but many people take them out to 36"hg and a few people are brave enough to go to 42"-43"hg. That's on a diesel with 18.5:1 or 19:1 compression ratio!

OTOH #3) A lot of the overengineering is bolt-on. E.g. I owned a 1980 RX-7...look in the engine compartment and you'd think it had a large engine, but when you actually studied it you realized that the carburettor (including the banks of soleloid valves and who knows what) was all you could really see. The actual engine was a little thing buried down in the mess. Strip that stuff off and you had a nice moderate performance car.

Which is just a fancy way of saying that free lunches do exist but often don't taste the way we'd like.

My #1 engine choice is a 13B or renesis... if it wasn't for the (constant speed) prop question, there'd be no question at all. I'm also really looking forward to seeing an egg west. Cable is just down the road from me.

I'm thinking seriously about how to mount a radiator in the back, but moving coolant around becomes an issue. At some point you will have 20lbs of coolant to get a 3% increase in cooling efficiency.

 

[RV7Guy]

What does Subaru think?

Just curious, does the Subaru company endorse the use of their engines in airplanes? And, two, what happens if they shut off the supply to Jan Eggenfellner who converts new engines for aircraft use? A lot of people would be left hanging.

The alternative engine thing isn't for everyone but I hate to see them go away for those who like to tinker.

 

[gmcjetpilot]

We have moved on

If you take the statistical view of QA, production quantity matters. When 1,000,000 engines of a particular type are produced in a given year, you can easily find out if there is a 0.001% failure rate....
My view...

1) Engineering is all bean counting. It is all about minimizing the cost of obtaining a target performance. That's why overengineering is so common.

2) The word "Overengineering" does not mean what most people think it means.

3) Auto makers employ many engineers.


OTOH #1) Many engine manufacturers want to sell a single product to multiple markets or use it in a variety of vehicles. E.g. GM uses the same basic engine in small cars and relatively much larger pickup trucks; VW sells the same engine in a car and as an industrial engine for running gensets and the like. As such they may not overengineer as much as they could.

OTOH #2) Sometimes, in order for something to work at all it must work very well. I own a VW TDI... which normally runs ~26"hg manifold pressure...but many people take them out to 36"hg and a few people are brave enough to go to 42"-43"hg. That's on a diesel with 18.5:1 or 19:1 compression ratio!

OTOH #3) A lot of the overengineering is bolt-on. E.g. I owned a 1980 RX-7...look in the engine compartment and you'd think it had a large engine, but when you actually studied it you realized that the carburettor (including the banks of solenoid valves and who knows what) was all you could really see. The actual engine was a little thing buried down in the mess. Strip that stuff off and you had a nice moderate performance car.


That said....
My #1 engine choice is a 13B or renesis... if it wasn't for the (constant speed) prop question, there'd be no question at all. I'm also really looking forward to seeing an egg west. Cable is just down the road from me.

Does it really matter? Who cares. I don't mean to be rude but we have moved on. I appreciate your insight but it has nothing to do with the topic or real premise, a better engine (installation) than existing air-cooled engines. If it is not faster or burning less gas who cares about the engine industry.

If you can't install a water cooled engine with reasonable weight, low cooling drag for a fair price and without massive airframe modification than it matters not.

We have moved on. The discussion about engineers, production volumn is a canard, a non sequitur. The only way the ONE SIZE fits all will work best is if its designed for it, from the start. The engine, the airframe, everything designed with that engine in mind for all applications. Hitler's engineers had the same idea in 1930's Germany with the VW, the peoples car. The aircooled VW engine was designed to run a car, an airplane and equipment from household to industrial equipment. That is why it comes out with a few bolts. Pretty smart. That has been done. Again so what? If it does not work as well as the "speciality" engine than its a compromise. I don't want a compromise.

The real issue for alternative engines is not what wrong with Lycoming but what it wrong with your alternative engine installation. As we have been discussing it is the installation. The engine is great on the Dyno. The secondary issues are the supporting systems, fuel, water, exhaust and prop.


Just buying what Eggy sells will likely not make the needed head way, because Jan is stuck with the design requirement of a bolt up installation. That is with out a doubt a compromise. Don't get mad at Lycoming guys, get rid of the compromise. Problem is the market is small, the profits are smaller, while liability is high. The first few lawsuits against Eggenfellner my put that company away. The real action and breakthroughs come from individuals, where production and easy installation are not a factor.


I wish Eggenfellner, RWS, powersport, Minstral, belted power all the luck in the world, but it has to go faster, burn less fuel and install in popular experimental airframes with little modification, while being more robust and not significantly heaver. Everything else is just peripheral. Smoother running and less oil changes are cool and all, but who wants to burn 1 gal/hr more and hour or go 15 mph slower? Also with out dispute water cooled installations are heavier, another challenge.

Folks like rv6ejguy, Tracy at RWS and many others are the ones the will come with the solutions, but they are not looking back at Lycoming, they are looking forward. I also wish you luck with your renesis engine. Wankel is great from power to weight and if I went with an alternative engine the renesis would be tops on the list, however you can expect to have more fuel burn and noise than other engines. However by flying high and leaning aggressively you can mitigate this draw back. A turbo does two things, adds more efficiency and lowers the noise. However you add weight, cost and complexity. I hope it works out for you the way you hope.

Tracy at RWS has been going faster and faster. He has won in the 160HP class, after many years of effort and refinement. As long as you realize you will (NOT) get 180hp Lyc, constant speed performance and are realistic you will enjoy it. Also it will take longer to build. However if you do it yourself you may save several thousands under a NEW Lycoming. I am guessing a Renesis is not cheap like a 13B is. I am not negative, just realistic in expectations from watching the progress of many alternative engine installations. (Also you will have to carry oil to add to the fuel or the injector, which I think is a pain, but that is what you have to do.)

George

 

[avaviat]

Dunno, George. To me, the demands and process which caused an engine to be what it is matters to how I might use that engine. I'll wax poetical about my TDI's engine as an example of great engineering... heck, I'll even wax poetical about my BMW's engine... but they would SUCK as airplane engines no matter how pretty your mount, or how slick your cooling system. They are slow turning cast iron heavy engines designed for a totally different task.

That is the basic question with sube conversions... and Tracy Crook conversions... and APU conversions, and any other "found engineering" project. The quality of the workmanship can be superb, the components can be marvels, everything can be top notch... and all of that effort and skill and and precision and expense can yield a mediocre result.

Spending a bunch of time worrying about how to route cooling lines and where to mount radiators to get a 3% improvement is silly if you start out with a 30% penalty. That's actually the genius of Tracy Crook IMO... he starts out saying "these are the limitations I'm accepting, and my reason for them is that my power plant will cost $8,000 total, so the fact that I'm a little draggy because I have a lame heat exchanger doesn't bother me" ... I'm all for that. The fact that he goes out and tinkers some more and improves his plane is nice, but those improvements are on his plane... to get the same results, you may well have to duplicate his tinkering for yourself IMO. (And I have most of Crook's videos/"books".)

My problem with the eggs and powersports of the world is that they take away that initial savings, leaving everyone looking for intangibles... looking for smoother rides, perceived reliability, a 0.2GPH difference in fuel burn, or whatever... and suddenly people are looking for 3% reductions in cooling system drag as a major factor.

Tracy at RWS has been going faster and faster. He has won in the 160HP class, after many years of effort and refinement. As long as you realize you will get 180hp Lyc, constant speed performance and are realistic you will enjoy it. Also it will take longer to build. However if you do it yourself you may save several thousands under a NEW Lycoming. I am guessing a Renesis is not cheap like a 13B is. I am not negative, just realistic in expectations from watching the progress of many alternative engine installations. (Also you will have to carry oil to add to the fuel or the injector, which I think is a pain, but that is what you have to do.)

Yep... if I go that route, I'll build myself. Renesis is more money by a large chunk... probably not necessary either, but I'm on the look-out.

I've done quite a bit of work on a 12B (in a car)... that's one of the reasons for my bias. Know the upsides and downs.

 

[jcoloccia]

My problem with the eggs and powersports of the world is that they take away that initial savings, leaving everyone looking for intangibles... looking for smoother rides, perceived reliability, a 0.2GPH difference in fuel burn, or whatever... and suddenly people are looking for 3% reductions in cooling system drag as a major factor.

This is just so right.

 

[gmcjetpilot]

Dunno, George. That is the basic question with sube conversions... and Tracy Crook conversions... and APU conversions, and any other "found engineering" project. The quality of the workmanship can be superb, the components can be marvels, everything can be top notch... and all of that effort and skill and and precision and expense can yield a mediocre result.

Spending a bunch of time worrying about how to route cooling lines and where to mount radiators to get a 3% improvement is silly if you start out with a 30% penalty. That's actually the genius of Tracy Crook IMO... he starts out saying "these are the limitations I'm accepting, and my reason for them is that my power plant will cost $8,000 total, so the fact that I'm a little draggy because I have a lame heat exchanger doesn't bother me" ... I'm all for that.

Awesome I totally get it, understand, appreciate and agree with your point of view. I get it. Also, concure Tracy is great, very sensible man with the right mix of enthusiastic mad scientist and pragmatic engineer. G

My problem with the eggs and powersports of the world is that they take away that initial savings, leaving everyone looking for intangibles... looking for smoother rides, perceived reliability, a 0.2GPH difference in fuel burn, or whatever... and suddenly people are looking for 3% reductions in cooling system drag as a major factor.

This is just so right.

Yep Right again. G

 

[dan]

Thrust measurement test results

He's doing a series of thrust measurement tests on different planes/powerplants and mine will be one of them. It'll be interesting to see!

You guys are gonna love this...we did the thrust measurement tests today at Robert's hangar. It was fun to say the least. And the data will speak for itself. No, I'm not going to give any hints. I do have a spreadsheet and some charts, but you ain't gettin' it until Robert's report is done...

 

[JohnR]

 

[jcaplins]

subbbb intent

It was my understanding that long ago the subaru boxer engine was originally designed and intended for aircraft use. Then quickly adopted for auto use.

I don't have any proof (yet). Anyone care to back me up or prove me wrong?




Jeff

 

[jcoloccia]

Maybe this is a stupid question, but is there a good reason why someone doesn't just design a propellor that will allow the Subies et al turn at their design RPM without a reduction drive? Just wonderin' why we've gone through all the trouble of redesigning the whole powertrain but then stopped at the propellor.

I'm sure some smarty pants out there will know a reason why this is a bad idea.

 

[Michael White]

Maybe this is a stupid question, but is there a good reason why someone doesn't just design a propellor that will allow the Subies et al turn at their design RPM without a reduction drive? Just wonderin' why we've gone through all the trouble of redesigning the whole powertrain but then stopped at the propellor.

I'm sure some smarty pants out there will know a reason why this is a bad idea.

John,
I'm not an Aero Engineer, so I can't offer lots of numbers for support, but the short answer to your question is TIP SPEED. Propellers get REAL inefficient when their tip speeds approach supersonic. The reduction drive is used to keep tip speeds reasonable. To keep tip speeds down you either use a PSRU or shorten the prop (shorter blades have lower tip speeds).

To go direct drive with the Wankel (which can easily do 7,000 RPM) you would almost have to go ducted fan. Somebody (can't remember who at the moment) did this with a VariEze a few years back, but switched to a normal pusher prop due to drag problems with the duct.

George (gmcjetpilot), I agree with your position that the only real solution is to design the entire sytem (airframe and engine) with the alternative powerplant in mind from the start. Trying to convert an air-cooled design to liquid cooling is, has been, and always will be a compromise from the start. The only kitplane I can think of that would be a good conversion candidate would be the Turbine Legend. Designed for a big block Chevy to start with, and still has a vestigal rad scoop on the bottom.

You could deepen the rad scoop back to it's original depth (or whatever you needed) and work from there. The downside? The kits are (a) out of production and (b) expensive ($150K+) even when they were in production.

That said, more power and all the success in the world to Tracy, Jan, RV6EJGUY and everyone else trying to make this work. I hope you all succeed.

Still contemplating a rotary for the RV-8 (but probably going Lyclone),

 

[avaviat]

Maybe this is a stupid question, but is there a good reason why someone doesn't just design a propellor that will allow the Subies et al turn at their design RPM without a reduction drive? Just wonderin' why we've gone through all the trouble of redesigning the whole powertrain but then stopped at the propellor.

I'm sure some smarty pants out there will know a reason why this is a bad idea.

The speed of sound.

Well, there is more to it. You want to couple your propulsion system speed to your plane speed. Turbofans are in a sense really fast props, and they work best on fast planes.

I used to build a few electric model airplanes... my "fast" models (45Kts) used direct drive 15,000RPM (and faster) props. My "slow" (4.5Kts) planes used gear reductions to spin large props at ~3000RPM. Both flew beautifully... but if you swapped powerplants (fast prop on slow model and vs versa) the slow model could barely climb and the fast model couldn't climb at all...

 

[gmcjetpilot]

Your both right, good question, but.....

The speed of sound.

Turbofans are in a sense really fast props, and they work best on fast planes.

I used to build a few electric model airplanes... my "fast" models (45Kts) used direct
drive 15,000RPM (and faster) props. My "slow" (4.5Kts) planes used gear
reductions to spin large props at ~3000RPM. Both flew beautifully... but if you
swapped powerplants (fast prop on slow model and viceversa) the slow model could
barely climb and the fast model couldn't climb at all...

Michael White and avaviat, you are both right.

jcoloccia, its not a stupid question, it has been thought of, but the design challenge is
just too great, and the law of physics just conspire to "get medieval on our buttock".

First avaviat, a Jet is in no way comparable to a prop. First they are ducted. The
tolerance between the fan blade and cowling is very small, basically Zero. They use
frangible rub strips and the blades do rub. A turbine blade is razor thin and made of
titanium mostly. The twist, the number of blades, "blade loading" and many factors
spell apples and oranges. Last it is not just a FAN. Directly behind the fan are
"stator vanes" and more blades. Way more going on to discuss here. Forget that
analogy, props spinning out in the open and turbine blades in a "duct" are two
differnt animals. The are like the same as your girlfrend's cat to a Tiger. Both have
fur.

Second avaviat, the tip speed is a little over 0.40 mach on your 15,000 rpm 51mph
model plane, which is about 1/2th the tip speed on a RV doing 200 mph with a 74"
prop turning 2,500 rpm. Your model's prop tips are well below supersonic. I assure
you if it was supersonic it would suck. Tip speed is a function of not only RPM, but
prop diameter and the aircraft's forward speed. A 74" dia prop is not a 7.4" prop.

avaviat, you are right, putting a slow prop on a fast plane or a fast prop on a slow
plane is bad news. Props are designed around a factor called "J" or the advance
ratio, V/nD, the ratio of velocity (aircraft speed) verses the prop RPM and diameter.
A prop that is efficient for a particular airframe or planned designed speed, will not
work well on another plane.

Also, model airplanes are not a fair example to a real airplane, because of thrust and
drag are out of "scale" to a full sized plane and prop diameters are small. However
your point is correct a prop for one plane is not good for another. It however does
not have too much to do with tip speed. If you change aircraft drag, HP or target
speed you change the optimal prop design.


What what about jcoloccia's question. A direct drive prop for a Subaru. The
punch line is supersonic tip speed. Over 0.90 you are in trouble.

Michael is very correct, as a prop tip speed approaches about Mach 0.9 efficiency
goes to heck. In fact Mach .85 is about all you want to get near with you prop tips.
A real fast RV at 2,700 can bump up to that 0.85M tip speed.

You can google this info. It does not mean fast turning props going mach 0.90 don't
work, but I can tell you a 68" 2-blade or 3-blade prop turning 4600 RPM on a plane
going 200 mph would have ugly efficency. The tip speed would be well over Mach-
1 by a large margin. That is unworkable. On take off at 6000 RPM it would be much
higher than that. This is like sailing with the anchor still out. What about a smaller
dia prop, or more blades, thinner, wider or curved?

Remember the unducted fan Boeing came up with in the 80's:
http://en.wikipedia.org/wiki/Unducted_fan and this is cool
C-130 Herc

The slower the tips the better for efficiency. Don't get efficiency and thrust mixed
up. Slower also means less thrust, but more thrust for given HP. So turning slower
will make you go slower, but more efficiency for HP you are putting into the prop
(prop HP). There is a trade off.

What about turbo props or those "unducted fans" on high speed turbo props? They
turn the blades slowly (see below). The problem of blades (props) and high forward
speed is it gets complicated, because the "vector" or tip speed from rotation and
forward speed work against you.

For sure RPM over say 3,000 to 3,200 gets to be problematic for any normal plane
(prop size and airspeed) similar to a RV. At some point, forward speed, prop speed
and thrust have to balance. I mean a solution to tip speed is just not turn it or make
the prop real small? However you will not go very fast with Zero RPM (zero thrust)
or small diameters.


High speed turbo props turn their blades real slow, like 1700 RPM. However these
blades are designed for this RPM and forward speed, not an after thought. Props
have only one RPM and speed they are best at. This is why Eggenfellner is going
to have problems with his new slow turning re-drive. Running a prop designed to
run at 2,500 rpm at 1,700 rpm is not going to work well. He is loosing
efficiency unless he has a custom prop made for that RPM, fwd speed, HP etc.....
All parts have to be designed to work together. Change one thing affect 10 other
things.


**************************************************
Factors affecting the prop besides the design of the prop itself are:
*RPM
*Air density
*HP available
*Aircraft drag
*Airspeed (climb/cruise)

Factors affecting performance due to prop design only:
*Diameter
*Number of blades (more is not always better)
*Blade design (thickness, plan&tip shape, twist, airfoil, chord vs station, area)
(Blades affect the Ct and Cp, coefficient of thrust and power)
**************************************************


There is nothing wrong with gear boxes. Lycoming and Continental have geared
engines. I think most of the radials have planetary reductions. There is nothing
wrong with turning the engine fast and prop slow, but for RV's you don't want to
turn your prop much over 2,900 RPM. The little Reno formula racers turn 3,000-
4,000 rpm, but they have smaller props and they are not going for efficiency, they
are going for speed; so they don't care about a little loss of prop efficency if they can
get enough additional HP out of their poor little engines to justify it the prop losses.
However there is a limit, and when you get to MACH 0.90 you are really making
noise not thrust. The Subaru needs to run 4600-6200 RPM. That is way to much,
unfortunately.

Most props run somewhere around 75% to 85%. That means 1 HP from the engine
gives you say 0.80 HP worth of thrust. More correctly it is equal to [(Thrust *axial
speed) / (resistance torque * rotational speed)].

A prop with 0.83 efficency in slow cruise may only have 0.79 efficiency in another
flight condition. So even an efficient prop can not be efficient over a wide range of
RPM's and speeds. This is worse for our 6000 RPM prop, that needs to work for
100mph to 200 mph and rpms from 3000-6000. A Normal prop only has a range of
about 500 RPM and +/- may be 100-140 MPH. Trying to get a prop to work over
3000-4000 RPM, over a wide speed range would be a hard trick. Unfortunately a
Subaru does not make much HP at 3000-4000 RPM.

Moral of the story, a prop has to be customize to the exact application and most
important flight operations. That is why the Hartzell Blended Airfoil is so ideal for
the RV, because it was designed specifically for the RV. Most other offerings are
generic, not exactly for the RV's: HP, speed, drag, altitude and RPM's. That is why
alternative engine set-ups suffer a little, due to lack of prop availability. I like Tracy
of RWS, he uses a fixed prop and deals with the loss of T/O and climb performance
for light weight and simplicity, not to mention lower cost.

NOTE: Prop efficency improvements and changes are measured in 10ths or even
100ths of a percent. To get 1% change is fantastic. That is why I doubt many claims
from prop manufactures who never tested their prop on a RV but somehow gained
tremendous efficiency all of sudden?

With all of Hartzells tweaking on the C2YR/F7496, BA Hartzell, they only got 3.5
mph more than the venerable Hartzell HC-C2YK, the previous standard prop for
180HP/200HP RV's. THAT IS AWSOME!! That is a 1.7% gain in speed. That is
some serious squeezing. They did it right. First the HC-C2YK is no slouch and is
faster than almost every "fancy composite prop" out there (except the WW 200RV
which was only 1/2 mph faster). However the HC-C2YK was made for the Mooney
and Comanche. A good match to RV's but not quite optimized.
Van's Prop
comparison

Its hard to get every bit out of a prop. However the Hartzell BA is the fastest prop
by 3 to over 8 MPH, compared to other brands. Hartzell addresses the experimental
market and offers props specifically designed for the RV, Lancair, Rocket and other
kits. I don't know of any other manufacture that actually tests and designs
specifically on and for the RV, except Sensenich.

Prop design and analysis is complicated, but I am sorry to say a direct drive prop on
an engine capable of running from 3000 rpm to say 6000 rpm, from 50 to 220 mph,
is a design task yet to be solved. Something could be done, but its beyond the scope
of what you would put on a little single engine piston plane, with 160-180HP. Its
too easy to make an engine that produce a 150-250 HP at 2,700 rpm direct drive
engine, Lycoming. (Sorry I had to say it.)

G

 

[avaviat]

George... "in a sense" was there for a reason... didn't say, or mean to say, that turbofans are really a bunch of sensenich FP props stuck in a length of pipe.

The real answer would be to change the problem domain. The speed of sound through hydrogen is roughly four times as fast as through dry air... so all we need to do is electrolyze the oceans, get rid of the oxygen (bind with iron from asteroids?) and we might raise the speed of sound enough to start spinning some faster props. I'm just spitballing here but I think it will work. Alternatively, water vapor at 134C gives you a 150 meter per second edge over 20C air... so perhaps it would take less energy to just boil the oceans and raise our cruise speeds that way. Work with me here....



I was really just offering a non-technical example of matching props to load. I could've said the same thing using a tug boat and a v-hull race boat as examples. As you know, you can drop the tip speed by shrinking the prop. Put a 36" prop on your RV and you can spin it very fast without exceeding mach 0.85... but throwing a small amount of air backwards at very high speed is going to give you the performance of a cozyjet.

 

[ship]

a prop is a fan is a prop

First avaviat, a Jet is in no way comparable to a prop.

c'mon. a turbofan IS a propeller. fancier, yes. but a prop nonetheless. just as a helicopter rotor is also a propeller.

a 777 has more in common with an RV than an F16 or a 707.

unlike a pure turboJET which produces thrust exclusively via it's exhaust (zero bypass), a turboFAN gets most of it's thrust by converting engine torque to thrust via rotating airfoils (high bypass).

put a shroud around a prop to increase tip efficiency, add blades to absorb more power, twist the hell out of them to deal with huge airspeed operating range, make them really thin to reduce drag, add vanes to reduce vortice drag....

viola....a fan is a glorified prop by another name.

ignoring the piston issue, the only difference between an 0-360/Hartzell and a GE90-115 is more power, more blades, more money and a big ol shroud

 

[cjensen]

ignoring the piston issue, the only difference between an 0-360/Hartzell and a GE90-115 is more power, more blades, more money and a big ol shroud

and a much cooler sound!!!

 

[gmcjetpilot]

Oh my

c'mon. a turbofan IS a propeller. fancier, yes. but a prop
nonetheless. just as a helicopter rotor is also a propeller.

put a shroud around a prop to increase tip efficiency, add blades to absorb more
power, twist the hell out of them to deal with huge airspeed operating range,
make them really thin to reduce drag, add vanes to reduce vortice drag....

viola....a fan is a glorified prop by another name.

ignoring the piston issue, the only difference between an 0-360/Hartzell and a
GE90-115 is more power, more blades, more money and a big ole shroud

Right, when you get all them there blades and shroud hooked up to your Subaru
Son, let me know, ha ha he he, lol, side hurting, laughing too hard, must stop...

"Turbofan IS a propeller, fancier.." To say over simplified would be over simplifying.
A clever mix of part truth with gross bogosity, but well done. Good luck with your
CozyRV Jet Subaru.


No offense, I got to be honest with you, it sounds like you think "add blades and
shroud" will get you a jet. You also allude to more HP and "vains to reduce vortice drag".

Look a supersonic prop or turbofan is a bad thing, even with a shroud, 30 blades or
what ever. Even the fan on a Turbofan jet engines does not like to go supersonic.
Ducted fan is another topic, I'll explain, but they don't do much for a big plane
(big does not = RC model).


("Vains" do not reduce "vortoce" drag in a jet engines. The stator vanes direct air
rearwards onto the next set of rotors so airflow (angle off attack) is optimized.
This reduces compressor stalls (yep like a wing) and converts velocity into pressure
with greater efficiency. Variable stator vanes was a breakthrough in the J79, about 1955
and used in the F-4/F-104. Sorry, I worked at P&W in Ct once and could not let that go.)

If you are implying adding more blades and a shroud will fix a prop going 6000 rpm on a
200mph plane with a Subaru engine, I got to say you're kidding, right. Your such a big
joker, next you'll tell us of plans to attach those 15,000-RPM electric motors on your RV.


A 40,000-70,000 lb thrust (now up to 127Kips thrust with the GE90) engine, can
turn a big 98", 110" or 117" fan. You are just having fun with me, but you do realize
a 160hp turning real fast (6,000-4000 rpm), even with multi (many) blade prop,
shrouded or not, will not work. Why? We went over that last class, supersonic.
I know you alluded to smaller and faster prop, but this is diminishing returns. Apples
and oranges, keep the RV model ducted fan an 15,000 rpm electric motors out of
the conversation, it is just not pratical, realistic or relative.

Fun fact: The GE90 (B777) fan only turns at 2550 rpm max! (hint hint)

How many full sized piston airplanes have you seen with ducted fan (not model
airplanes)? Not many because what works for scale RC models, is not always valid
at full scale. I know you are thinking of those scale models with ducted fans and
screaming RC model plane engines. Look a COZYJET is a Turbojet, forget
model airplane ducted fans for full scale planes. Its not going to happen. That is
why engineers always test full size engines and airframes. A "ducted fan" has a major
disadvantage, over 90-100 mph the drag (of the shroud) becomes higher than any
advantage it might give, and of course gets exponentially worse as speed goes up.
Google ducted fan and you will see mostly RC model. (Turbojet =/= Ducted fan)

The weight of shroud/blades is not justified for 160 hp Subaru engine. YOU WILL
NEVER EVER GET A "PROP" TO TURN 6000 RPM TO WORK. Geeeee. Supersonic TIPS
do not work especially with prop airfoils because they are too thick. Its like trying to go
MACH 2.8 with a Piper cub wing, even if it was made of un-a-tanium (clear aluminum).
I know you think SUPERSONIC is no big deal, but you are in 7" (or less) prop RC land.

Ship, you have a lot of facts, some right, but they are disjointed and not quite relative
to each other. A piston plane engine is not a jet, attaching a jet "FAN" on a piston plane
will not work and RC model planes are not like full size planes, roger, copy, over?
You can't baffle a BS'er with BS. G


PS TurboFan: Fans do go supersonic, you hear it on takeoff (the whine). That
is one reason we cut back power, noise. However supersonic is bad, and engine
engineers would LOVE to slow the fan down. However it is connected to the
compressor (low pressure at the back end), and the engineers have to deal with it
at high power. If they could they would turn the fan slower, but gearing it too heavy.
That is one reason why Rolls Royce has "three spool engines", so they can turn N1 (fan)
slower while N2 and N3 can scream. GE and Pratt are two spool engines.

"Hear me now, believe me later" supersonic FANs or Props are BAD, and we don't like'ee.
There are ways to deal with them (sweeps, ultra thin) but this exotic stuff for a RV, OK.

 

[n85pw]

Subie Overhaul

A friend of mine has one of these Subie engines on his RV and swears by it. I am a Lycoming guy and will stay that way til you know what freezes over.

Anyhow, my friend with the Subie engine, blew a piston on his engine after 72 hours of flight. I witnessed the event and notified him of significant smoke coming from his airplane, while he was in flight...and saved hi a@@.

Nonetheless, he had to replace his entire engine block along with all four pistons. The total cost for the overhaul, around $3,500. Not too bad. However, having do to that after ever 70 hours of flight could be costly. Compare that to an overhaul on a Lycoming after 2,000 hours (see below):

Subie overhaul every 72 hours - $3,500
Subie overhauls over the course of 2,000 hours $97,222

Lycoming overhaul after 2,000 hours - $18,000

You be the judge.

 

[cjensen]

A friend of mine has one of these Subie engines on his RV and swears by it. I am a Lycoming guy and will stay that way til you know what freezes over.

Anyhow, my friend with the Subie engine, blew a piston on his engine after 72 hours of flight. I witnessed the event and notified him of significant smoke coming from his airplane, while he was in flight...and saved hi a@@.

Nonetheless, he had to replace his entire engine block along with all four pistons. The total cost for the overhaul, around $3,500. Not too bad. However, having do to that after ever 70 hours of flight could be costly. Compare that to an overhaul on a Lycoming after 2,000 hours (see below):

Subie overhaul every 72 hours - $3,500
Subie overhauls over the course of 2,000 hours $97,222

Lycoming overhaul after 2,000 hours - $18,000

You be the judge.

ballsy first post, i'll give you that!

you're numbers make no sense (they do add up, so congrats on doing the math right, but...), and are not even close to reality. you're saying that because of his particular engine problem, that this is what ALL subies are going to do at 70 hours. hmmm...

well, i can do the same thing, and tell you that we had an engine failure on a lycoming with 40 hours on it. wow, lycoming overhaul every 40 hours!! talk about high dollar!!!

c'mon!

 

[rvatornate]

A friend of mine has one of these Subie engines on his RV

Here we go with the friends again Could you pass on some info such as: was this a self rolled engine setup or from one of the FWF packages. To imply that because he had issues at 70 hours, the cost to reach 2000 for sube engines would be near $100,000 is crazy.

Nathan Larson
N217JT RV9E 460+ hours still no overhaul EggSube 2.5

 

[Scott Will]

faster is not better

To add onto George's post...

A good example of getting the fan at a lower speed is the PW8000 being developed by Pratt & Whitney (disclosure: I used to work at PW in East Hartford, CT). It's a geared turbofan version of their PW6000. Designing a turbofan is always a compromise. Trade-offs are just the nature of aircraft and engien design.

Here's a link to a description of the advantages of a geared turbofan.

And from the PW website itself:
The PW8000, the next leap in engine technology, is an extension of the smaller PW6000 family. The ?green? PW8000 engine will reduce fuel burn 9 percent and cut noise levels 60% below the quietest of today?s engines. Because the geared turbofan design is more efficient, the engine requires 40 percent fewer mechanical parts in the air-compression system and half the number of airfoils. An aircraft flying with two PW8000s will cost airlines about $600,000 a year less to operate and maintain than one powered by a conventional engin

 

[n85pw]

The engine that was on the RV was from Eggenfeller, it was not a "homebuilt" engine that was self rolled. This was from Egg's company and installed on the airplane as per his plans.

The point here in this email and with my original one is that a Egg engine needed to be overhauled at 70 hours, which is premature for any engine. It happened and had to be dealt with and was handled in an expedited fashion.

There were thoughts that the fuel (reformulated gar gas with ethanol) being used was not the right or that the supercharger was being used beyond its limits at an altitude substantially less than 8,000'. Those items may have lead up to the piston having a hole in it.

I am not an engine guru nor claim to try and be one; however, the point here is that this happened and it would be wise to notify others of this in order to prevent it from happening again to those that are using Egg's engines.

 

[mlw450802]

gotta LOVE altruism....

 

[cjensen]

that would've been a much better way to intro yourself to the group...

your first post just came across as saying those engines don't last, and will cost a hundred grand to get to 2000 hours (and like nate said, one of the "my friend has..." stories). just not even close to what the engines have been demonstrating so far. the guys that i know that are running the egg engines are getting some decent time on them now, and are without issues. i don't know how many egg's have had early work done, but i have seen pleny of lyc's, conti's, etc. in the shop for early work as well. it can happen to any engine, although in this case, as stated in your second post, it sounds like it may well have been operator error...

 

[avaviat]

George, you are bogging yourself down in details. It's the danger of Jargon... you can't see the trees for the Abies lasiocarpa, Acer distichum, and Quercus rubra. The upshot is that details are very impressive sounding, but impressive sounding doesn't actually matter when building a bonfire.

As your post indicates, turbofan fans *are* props, with many of the limitations of props. This is absolutely true in the same sense that the observation "props are wings" is true. Does it mean you can bolt a hartzel on each side of your fuselage and go flying? Probably not. Does it mean that each operates on identical principles, in a similar environment, and they share limitations? Absolutely.

It would be easy to make a prop that spins 6000 RPM without going supersonic. a 30" prop would have a rotational velocity of about 785FPS (no need to get into translational velocity for this converstaion)...no problem. 30"&6000RPM is a perfectly reasonable size and RPM to make an efficient prop....just not an efficient prop for an RV flying in a standard Earth atmosphere... which gets back to that whole "speed of sound" thing.

The reason a turbine can spin faster is that its internal prop blades (said that way just for you George) do not operate in a Standard Atmosphere... raise the temperature, raise the pressure, and you raise the speed of sound. Change the gas mixture (add partially burned hydrocarbons, water, CO2, etc) and you also change the speed of sound.

As for implying that people are talking about model airplanes: To be blunt, the conversation has moved on and we weren't talking about that any more. As papa tomato said to the baby tomato who lagged behind, ketchup!

 

[rv8ch]

Subaru engine

Anyhow, my friend with the Subie engine, blew a piston on his engine after 72 hours of flight. I witnessed the event and notified him of significant smoke coming from his airplane, while he was in flight...and saved hi a@@.

Wow - his engine blew a piston and continued to run? Pretty tough little engine!

Nonetheless, he had to replace his entire engine block along with all four pistons. The total cost for the overhaul, around $3,500. Not too bad.

That's for sure! Rather cheap, I'd say.

However, having do to that after ever 70 hours of flight could be costly.

Har, Har! I guess since your friend still swears by his Subaru, he doesn't anticipate an overhaul every 70 hours. Perhaps every 140!

 

[gmcjetpilot]

Earth calling

you can't see the trees for the Abies lasiocarpa, Acer distichum, and Quercus rubra.

do not operate in a Standard Atmosphere...

raise the temperature, raise the pressure, and you raise the speed of sound.

Change the gas mixture (add partially burned hydrocarbons, water, CO2, etc) and you also change the speed of sound.

As papa tomato said to the baby tomato who lagged behind, ketchup!

Doha! huaaaa?

"do not operate in a Standard Atmosphere"

Is that where you are, in outer space? That explains it. Cheers G

Ship; To be honest you are the one who disputed tip speed when a question was posed, asking about direct prop drive off a Subaru, and you gave an example of your model RC plane with a 15,000 rpm electric motor and something about Turbofan jet engines. I pointed out that your RC model's prop tip speed was only about Mach 0.40, even at 15,000 rpm due to the tiny diameter. You replyed about (I quote), "hydrogen", "electrolyze the oceans" and "iron from asteroids".

Look tip speed is important. Efficency goes to S#@t above 0.90M. A small diameter prop will NOT ever, ever, work on a RV because the "thrust required" for a 1,800 lb plane, even at 6,000 rpm. Your "RC model" weighs less than a pound, I guess. Its like saying to go faster in a RV chop off 2/3rds of the wing, Shazam! less drag. Shazam! less lift. At some point you can't fly. At some point you can't get enough thrust. You NEED prop diameter. Direct drive prop on a Subaru WON'T WORK EVER. I think we are done.

 

[gmcjetpilot]

Great first post, welcome aboard

A friend of mine has one of these Subie engines on his RV and swears by it. I am a Lycoming guy and will stay that way til you know what freezes over.

Anyhow, my friend with the Subie engine, blew a piston on his engine after 72 hours of flight.

Subie overhaul every 72 hours - $3,500
Subie overhauls over the course of 2,000 hours $97,222

Lycoming overhaul after 2,000 hours - $18,000

You be the judge.

Welcome to the group, GREAT first post, I got the humor, but got to take you to task on an Lycoming overhaul, which is only $6,000-$8,000 in parts/machine shop, plus labor if you farm that out, about $2K or $4K, for a total of $8K to $12K total. You meant you can buy a whole Lyc for $19.5K.
George

 

[cjensen]

a Lycoming overhaul, which is only $6,000-$8,000 in parts/machine shop, plus labor if you farm that out, about $2K or $4K for a total of $8K to $12K total. You meant you can buy a whole Lyc for $19.5K.
George

george, i'm really curious where you get your prices? at work, we can't get original lycoming cylinder assembly's for less than about $1200 apiece. that's JUST a cylinder. i would agree you could TOP overhaul a four cylinder lyc for your $6-8k range, but not a major. we overhauled the lyc in our 152 three years ago for $10,000. that's an O-235!

in my cherokee, we bought a lycoming reman from air power two years ago for $17,000 with a core exchange (an overhaul was gonna be $14,000). if our core was bad, it was another $9,000 (i gave them the $9,000 check to hold, luckily our core was good), which meant a reman outright was $26,000. and we did the work ourselves, so there was NO labor charge.

 

[osxuser]

I'd imagine that price would be overhauling the current cylinders, replacing the bearings and seals, and doing the work youself. However, you can get new Lyc cylinders for $989 from airpower, or SAP ones for $889. The bearing kits aren't that expensive, and not much else goes wrong with a regularly flown lycoming...

 

[gmcjetpilot]

Ain't Experimental Great

george, i'm really curious....lycoming cylinder assembly's for $1200 apiece. that's JUST a cylinder....TOP overhaul a four cylinder lyc for your $6-8k range, but not a major. we overhauled the lyc in our 152 three years ago for $10,000. that's an O-235!

in my cherokee, we bought a lycoming reman from air power two years ago for $17,000 with a core exchange (an overhaul was gonna be $14,000). if our core was bad, it was another $9,000 (i gave them the $9,000 check to hold, luckily our core was good), which meant a reman outright was $26,000. and we did the work ourselves, so there was NO labor charge.

I am a BIG FAT lying son of a biscuit.

http://www.mattituck.com/ (O-360 $19,490.00)
Link above: Go to experimental engines, TMX-360, and scroll to prices.

http://www.aerosportpower.com/Prices.htm
$19,300.00 for a new O-360, constant speed $19,800.00


Now complete assemblies Jug, piston, rings, valves and everything, bolt on are $900. Times four I get $3.6K, but no more than $4k. To take them off and put on is a few hours? I don't get $6k to $8k. I guess if you just brought it to a shop they could charge $2k or $4k in labor. Especially if they have a boat payment coming up. With experimental we we are going to take the cowl off, and strip the engine at least. Cylinders are easy to take off. I just don't see more than a few hours of labor, may be 4-8 hours. $100/hr that is $800. Remember you don't NEED new cylinders when you OH, you can replace everything in a JUG full up all labor for $385+pistons/rings, so you can save $1.5k OH'ing the old ones. (no debate please on OH/new, it is what it is.) http://www.dongeorgeaircraft.com/cylinder.htm

You got screwed on your O-235. No really O-200, O-235's are EXPENSIVE. They cost more to maintain, the parts are WAY more expensive than a O-320 or even O-360. Sad but true. There are just less of them, so they charge more. (HINT DO NOT USE A O-235 IN YOUR RV-9, PUT A 320 IN.)

They know you need that exact engine. You have to remember that certified caries a price premium and the mechanics have to make a living. As far as certified aircraft you are bent over and lubed, OK. In an experimental I can get any engine or part from any manufacture and put it in my RV. I am running a certified genuine Lyc O-360A1A by the way.


If you check the price of a "non certified" engines with parts from ECI or Superior (funny they are made of 100% certified PMA parts), built-up and sold by Aerosports or Mattituck for example, you will see the price of a Carb 320 or 360 is under $20K, BRAND NEW. Take that to your USED out right $26k engine shop. Unfortantly if you have a Piper you are out of luck.

That is why we are in experimental aircraft. They cost less and perform better.

I overhauled my O-360 in 2001. I and a A&P/AI friend took it apart and sent out almost everything to ECI. All parts overhauled and tagged, new everything, pistons, rings, valves, seats, oil pump and everything Lycoming requires to call it an overhaul. I DID not buy new cylinders. Nothing wrong with old cylinders if they are good. They are designed to be overhauled. Most go new because with three makers of Jugs (Lyc ECI, Sup) the price is low ($900). The price diff between new and rebuild has gone down, but there is still savings to be had with OH Jugs. Rebuilders like NEW better because there is less liability, but it cost you, the customer more. An overhauled jug is less than $400. Since my AI friend had the tools to overhaul and lap the seats, it was much less. The rejection rate is higher for old cylinders and frankly some people put welded crap on. New Jugs come with a warranty and the re-builder has some protection. If they overhaul it and it cracks the next day they have to take it off. New the manufacture has to pay for parts and labor. Mine where fine and only had a little over 2600 hours since new, chromed once. Bottom line is it all came out to less than $6k, plus $$ and beer for the friend, plus $700 for a carb OH and $2K for electronic ignition. I paid $2K for the core, which was good. The engine was signed off as overhauled to certified standards, except for the experimental EI I put on. That was that, about $11.5K for the whole "kit and caboodle" outright (including the OH items bought outright below with out hoses). Granted I got a deal on the core, but I was lucky.

I did not include the oil cooler ($160 for a OH SW unit), prop governor (yellow tag $400 Woodward, very proud of that deal, shops extra stock). I bought them outright OH but have less than $600 in to those. I did not include hoses, which your overhaul no doubt included? (Oh yes my friend gave me a low time fuel pump when he upgraded to FI and needed a Hi-P pump. Free is good.)

After I did my OH a few years ago, I called around for quotes and got a low of $10,000 to $14,000. So I felt pretty good, because with out the $2K EI, and $2K core, I had about about $7.5k into the overhaul if the "short block". If you tear it down and send it out, buy new parts yourself, you need to get the wholesell. Because they have one price for engine shops and one for you and me, but it is not hard to get the discount. Just make sure you don't pay retail for parts and machine shop work.


Still I can't justify the prices you paid (O-235 $10,000) and ($14,000/$17,000/$26,000), but $14,000 is not that far off for the going rate for a O320/360 overhaul. You can shave a grand or two with used OH jugs and do it yourself, but your hands are tied a little with certified. I assume the price of your overhauls included the Carb/FI, Mags, fuel pump, houses, prop gov, new everything and dyno test. I would expect to pay $14k for my O-360 if I threw my hands in the air and said do it all, and touched nothing, expecting FWF new or overhauled everything. It is like building a house. You can sub contract it. Go out and get the best price on carb overhaul, on mag overhaul, on Jug OH and so on, but that takes time, shipping. Again they have to make a living. You are paying about $2K to $4k for labor, dis-assembly/assembly. The nice thing is the warranty (I hope you got one) and break-in dyno. That is worth a couple of grand to me. If my engine did not "work out" I was out of luck. So its like insurance. Also the Dyno is nice, wish I had that. If the shop does not have the Dyno capability, I would not expect to pay a premium price for the overhaul. Some will offer that ala-carte. I would think $14k got you the Dyno/break-in.

Anyway you can shop around and negotiate the price. Lycomings are dead nuts simple, not hard to work on. It is just with certified they got your nads a lot more.

Why they charge $17,000 for exchange? I guess it is a $3K premium for the pleasure of doing the exchange and quick turn. As far as the $9,000 core that is just a good ol plan screwing. If the crank was bad, they should only charge you for that ($4k-$5). If the case or cam was bad they should charge for that. The $9K penalty is crazy, but that is to keep people from sending in junk that was sitting on the bottom a lake; I guess. $26,000 is approaching the new retail price from Lyc.

Lyc gives discounts to home builders. Lets say you had a Mooney that used a O360A1A and you wanted a new one from Lyc, they would charge you more than a RV'er can buy the same engine from Vans. In part because they have to compete with ECI and Superior. I think re-builders also discount work to home builders, even for the same work. I suppose they don't have to keep the same records or some horse hockey reason for charging less. I think its they know we are picky-chiseling-cheap-skates and will shop around for the lower price.

There is no magic except I guess we (experimental) can buy a Lyc clone for less than $20K made of ECI or Superior parts. The engine is NOT certified but is made of certified parts. You see this with avionics, TSO or non TSO, same thing but the non-TSO cheaper. Superior was selling non-certified engines as ECI and still does, but they now have gained certification. SO they can sell engines to the factory plane group. Guess what? Same engine but will cost many many $1000 more. Why? I guess the price bump covers certification cost; at least that's the story and they are sticking to it.

Experimental guys get the discounts.

G

 

[rv8ch]

And Eggenfellner says...

The engine that was on the RV was from Eggenfeller, it was not a "homebuilt" engine that was self rolled. This was from Egg's company and installed on the airplane as per his plans.

The point here in this email and with my original one is that a Egg engine needed to be overhauled at 70 hours, which is premature for any engine. It happened and had to be dealt with and was handled in an expedited fashion.

There were thoughts that the fuel (reformulated gar gas with ethanol) being used was not the right or that the supercharger was being used beyond its limits at an altitude substantially less than 8,000'. Those items may have lead up to the piston having a hole in it.

I am not an engine guru nor claim to try and be one; however, the point here is that this happened and it would be wise to notify others of this in order to prevent it from happening again to those that are using Egg's engines.

Very true. In order to find out what happened, and how I can avoid the "70 hour overhaul syndrome", I asked Jan Eggenfellner, and here is what he said:

...he was flying a supercharged, high output engine on 87 octane auto fuel. This of course, does not work in any engine.

 

[gmcjetpilot]

Reality Check

You know Alternative engines where promoted as better, more modern,
more reliable than "Lyc-a-sourus", and it shakes some up in the Alt eng
group when you point out a catastrophic failure. The reaction is to blame the
pilot or attack Lycoming for some reason. All very counter productive.

Fact anything can fail. Even though the Subaru engine is the 8th wounder of
the world , its subject to failure, so is Wankel, and so is Lycoming
and so is everything mechanical. Also adding superchargers and turbos puts
more strain on engines, 87 Oct or not.

I promise there will be more Subaru's sucking and eating parts. Not because
they are bad or worst than so-and-so, but statistically engines fail; the more
in service the more will fail. So while some ALT guys gloat about some Lyc
recall or engine related accident (and I know you do because I see it on
builder web sites), it is faults security. It is not for inferiority or strength in
the Lycoming, it is because of statistics. Really it is the systems, electrical,
water and fuel, that is the achilles heel of ALT engines, due to the increased
complication and reliance of outside systems to make it run. Burnt piston or
thrown belt, both can stop a Subaru. So be nice to us Lyc'ers, because we
are sensitive about our crank recalls.


I HAVE GAS

As far as gas, Lycomings (most now a days) are only 100/100L Aviation gas.
Only Lyc, the 320/150hp, is a 80/87 octane engine. I know what to put in my
engine, because Lycoming does NOT recommend any gas other than Aviation
fuel.

In the Subaru it is less clear. It is a a car engine. It does not have the Cat
converter, but does it still have an O2 sensor. The lead in aviation fuel will
eat O2 sensors, if its indeed still retained. Is it?

G

 

[avaviat]

Doha! huaaaa?

"do not operate in a Standard Atmosphere"

Is that where you are, in outer space? That explains it. Cheers G

Way above you anyway.

Ship; To be honest you are the one who disputed tip speed when a question was posed, asking about direct prop drive off a Subaru, and you gave an example of your model RC plane with a 15,000 rpm electric motor and something about Turbofan jet engines. I pointed out that your RC model's prop tip speed was only about Mach 0.40, even at 15,000 rpm due to the tiny diameter. You replyed about (I quote), "hydrogen", "electrolyze the oceans" and "iron from asteroids".

It was not ship who cited the RC model. Nor did he make point out the speed of sound of hydrogen. Please try to pay more attention. I'm sure ship is a nice fellow but I do not appreciate you crediting him with my ideas.

Now, to address points in no particular order:

1) You are low on the tip speed.
2) You are low on the weight.
3) The speed of sound is too slow and that should be fixed.
4) Technically, you mean "won't work well" in the section I deleted, which was my whole point.
5) Lead will destroy lambda sensors in about 100 hours when running 100LL. Lambda sensors cost about $18-40 depending on what sort egg uses.
6) Does egg really use a lambda sensor? You can make a reasonable ECU without one (though they are handy).
7) You can kill a carb. lyclone by leaning it out improperly. You can certainly kill any engine that doesn't have a knock sensor and a good ECU by fitting it with a supercharger and giving it straight 87 octain road fuel...if he wanted that he should've done water injection.



I'll finish up with a quote: "A foolish consistency is the hobgoblin of little minds." -- Ralph Waldo Emerson

 

[rv8ch]

Which fuel in an Eggenfellner Subaru?

In the Subaru it is less clear. It is a a car engine. It does not have the Cat converter, but does it still have an O2 sensor. The lead in aviation fuel will eat O2 sensors, if its indeed still retained. Is it?

From the Eggenfellner engine manual: http://www.eggenfellneraircraft.com/EngineStartup.htm

• Run 87 octane automotive fuel if normally aspirated.
• Run 93 octane automotive fuel if supercharged.
• Use TCP additive if running 100LL avgas.

 

[gmcjetpilot]

Just a typo

It was not ship who cited the RC model. Nor did he make point out the speed of sound of hydrogen. Please try to pay more attention. I'm sure ship is a nice fellow but I do not appreciate you crediting him with my ideas.

No I got it right; I was talking about you. It was a typo; I missed typed the p.

G

PS:
Your No. 7) "You can kill a carb lyclone by leaning it out improperly."
Sorry, correction, YOU would kill a Lycoming, but most student pilots can handle it;
you should stick with a Subaru, it's easier. Don't forget to change that O2 sensor
every 100 hours, lol.

 

[cjensen]

we're on the same page george...like you said i was putting a certified engine on a certified airplane. i think the confusion here is that when you say lycoming, you mean ALL lycoming types, so yeah, you can get a "lycoming" type brand new for less than $20k. not a LYCOMING though. those are over $30k (and you still need baffling, exhaust, oil and fuel lines, etc, etc, etc...). anyway, we went with the $17k remanufactured motor because it was a "0" timed engine. the $14k O/H would not have been. it would have been "0" SMOH, but not zero time. i think we did fine, but that was before i got involved in the wonderful world of experimentals! that's where my numbers for the cherokee came from. it did not include oil hoses, O/H exhaust, etc...we built the baffling oursleves. that was cool doing that!

anyway...

You know Alternative engines where promoted as better, more modern,
more reliable than "Lyc-a-sourus", and it shakes some up in the Alt eng
group when you point out a catastrophic failure. The reaction is to blame the
pilot or attack Lycoming for some reason. All very counter productive.

the sube we're talking about here wasn't catastrophic. it was still running, and brought him back to the airport. no shaking up here. he was running the wrong fuel for a supercharged engine. plain jane simple mistake. a bad one though.

 

[avaviat]

No I got it right; I was talking about you. It was a typo; I missed typed the p.

G

PS:
Your No. 7) "You can kill a carb lyclone by leaning it out improperly."
Sorry, correction, YOU would kill a Lycoming, but most student pilots can handle it;
you should stick with a Subaru, it's easier.

Ahh, we have a formal debater! I do love to see the classical forms followed.

So the sube is easier to manage in flight? That is the best argument I've heard for going sube, far better than smoothness or a few thousand dollars in total cost. The practice of loading every little task onto the pilot is bad human factors engineering. A pilot doesn't individually control the left and right ailerons even though there would be benefits to doing so...why should they individually control every last detail on the engine? A dedicated ECU (or a diaphram for that matter) will do a better job with fewer errors.

I still think I'll stick with the rotory if it is all the same to you. Well, rotary if I go alternative. If I can convince my father to take my bearhawk plans and start building then we'll probably (70% chance) build up two rotaries at the same time. If not, I'll probably go lyclone. But I'll definitely have an ECU that manages the mixture for me whatever I do. Can't be too careful....

Actually, I was thinking the other day that what the world really needs is a wankegnome... no, get your mind out of the gutter... I'm talking engines here!