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  #31  
Old 03-21-2012, 01:01 PM
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Not that I call real data. There are so many different air frames and propeller pitches going on, nothing all that specific. You can throttle back and see 3.5 gallons an hour (on regular grade gasoline WITH ethanol), general consensus seems to see about 5 gph cruise, but far too many variables yet to set a number in my opinion. Additionally, in my opinion the intake manifold is a joke, the better one coming out will change those figures anyhow.

Quote:
Originally Posted by Jerry Cochran View Post
Hey Don,

If you are talking about Eggenfellner's Viking, is there real world data on efficiency?
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  #32  
Old 03-21-2012, 01:08 PM
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Quote:
Originally Posted by airguy View Post
Ahhh, but that gets down into personal choice. Some people will prefer to carry an extra 3000 pounds of steel cage around them on the highway for impact protection, while others are perfectly happy riding around in a ball of tin foil. Going by a seat-miles rating would not be realistic because we would be comparing a Ford Focus to a Chevy Crew Cab.

It takes energy to move mass (as long as friction is considered, orbital mechanics are a different animal) so the ton-mile/gallon would be a truer measurement tool of energy efficiency.
It seems to me you two are talking in terms of "efficiency" but you haven't agreed upon what that term means. This is a subjective term that needs clarification anytime it is to be used in a discussion such as this. Which is exactly what Greg originally posted (in his own words). Greg's definition is proving to be different than Phylan's. Now the question is which perspective should be used?

Now, for my thoughts on the subject. . . oh . . . well, on second thought, you guys really don't care to hear about that I am sure.

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  #33  
Old 03-21-2012, 01:09 PM
David-aviator David-aviator is offline
 
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Quote:
Originally Posted by bret View Post
And why can I run 11.5-1 CR, 230 PSI static cylinder pressure in the Olds on 91 octane. OK, I know I am going to get slammed here but bring it on, this is how new ideas get started. There are a lot of folks here way smarter than me so lets share some CONSTRUCTIVE criticisms and thoughts. I bring this up because of the ever increasing price of fuel and the possibility that 100LL may change. I know some here are using 91 Oct right now, but at the cost of low compression and HP. I remember reading an article a long time ago about Quench chamber heads, I built and blueprinted a engine, forged full floating pistons, file fit rings, align hone the mains, "0" and square the deck, balance, ported intake, heads, headers, used aluminum heads with Inconel exhaust valves and had the quench area @ .030" this produces a violent and internal turbulent event to both cool hot spots and induce A/F mix across the combustion chamber to reduce detonation. In fact a test engine was built and the lower CR engine, with .060" quench heads had more detonation than the High compression engine. Along with this is a lot of custom cam profile timing and ignition curve profile, O, and carb jetting bla bla bla, yes this is all car stuff but you get the idea. So, then you will say, it is not continuous full load, well then we can look at Mercruiser race engines and Cummins turbo charged 18-1 engines and so on. All I am saying is, why are we still in the dark ages? Is everyone afraid to try something new, and no, I am not talking about car engines in planes, I am talking about aviation engines and stepping up to the plate with all this technology available. Twin quinch non hemi head? anyone, anyone, Bueller.....
Instead of writing about the issue and asking the same old questions, why not go ahead and do it and report back on why it works - or why it doesn't work.

There's a ton of stuff written about alternative engines, most of it by dreamers, but not much real world success. Many have tried, many have failed - mostly for lack of market, money and no improvement in efficiency.

Come up with something more efficient, more reliable and at a reasonable cost, it will be a success. Go out an do it and report back.
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  #34  
Old 03-21-2012, 01:34 PM
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I should have been more clear in my first post, I am not a fan of auto engines in aircraft, I was thinking of ways to improve the Lycoming base engine, like head design, most engines, gas and diesel use 4 or 5 valves, roller rocker arms with correct geometry to reduce valve tip side load, compression chamber design. Tuned intake runner dia. and shape to match the speed of the incoming air to utilize air mass for inertia supercharging. Tuned exhaust for max cylinder scavenging, I think 4 into 2 into 1 works well. Piston oil sprayers to cool the piston. A fuel system that atomizes the fuel better and delivers the fuel timed with the intake valve events. ect.....
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  #35  
Old 03-21-2012, 01:43 PM
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http://www.adeptairmotive.com/pages/26011

And, still in the game we have http://www.deltahawkengines.com/status00.shtml
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Last edited by Mike S : 03-21-2012 at 02:04 PM.
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  #36  
Old 03-21-2012, 01:44 PM
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My only beef with a Lyc is cost. It is a great performing machine, but it is a 4-cyl, pushrod valvetrain, aircooled, direct drive engine. How expensive should that be? By my (rough) calculations, assuming the highest quality, the retail value of the engine itself should be around $5k. It should come in fully dressed with a modern fuel and ignition system for less than about $9k. If it did, sales volumes would be much higher than they are today and that alone would spark a considerable amount of innovation and development. I don't know where all of the cost is (or isn't), but it is a killer when you look at a new certified engine for ~$35k or experimental for ~$25k. What I think we should concentrate on is how we can make a 2-place certified ready to fly machine available for ~$50K retail and a 4-place for ~$80k. That's what the 1965 to 1975 CPI adjusted price of a Cessna 150 and 172 is.

Tim
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  #37  
Old 03-21-2012, 01:56 PM
WingsOnWheels WingsOnWheels is offline
 
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Quote:
Originally Posted by rv6ejguy View Post
HP is actually the motivating factor on all vehicles. HP= work, torque = force.

You will notice that BSFC is rated against hp, not torque.
Very true, but you can increase the HP output of most engines by increasing operating rpm (to a piont). HP doesn't tell the whole story for an engine that must drive an rpm-limited propeller. Most 1 liter motorcyles these days are putting out close to 200hp, that doesn't mean it will work on your RV-6/7/8. The 10,000 RPM peak hp output would be a problem. Aircraft engines run at low RPM because they have to and the design of the engine reflects that requirement. The point I was trying to make by noting the high torque way that just because the hp numbers are low does not me the engine is a poor design. Try to find another engine with the same output at that RPM (even with a reduction) for the same installed weight. You won't.
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  #38  
Old 03-21-2012, 02:12 PM
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Quote:
Originally Posted by Mike S View Post

WOW! they just flight tested this last thursday.
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  #39  
Old 03-21-2012, 03:00 PM
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Quote:
Originally Posted by bret View Post
I should have been more clear in my first post, I am not a fan of auto engines in aircraft, I was thinking of ways to improve the Lycoming base engine, like head design, most engines, gas and diesel use 4 or 5 valves, roller rocker arms with correct geometry to reduce valve tip side load, compression chamber design. Tuned intake runner dia. and shape to match the speed of the incoming air to utilize air mass for inertia supercharging. Tuned exhaust for max cylinder scavenging, I think 4 into 2 into 1 works well. Piston oil sprayers to cool the piston. A fuel system that atomizes the fuel better and delivers the fuel timed with the intake valve events. ect.....
I hear you Bret, but the simple answer to your question is probably expressed in two words - reliability and cost.

In single-engined airplanes, flown beyond gliding distance from home, we WANT performance, but we DEMAND reliability. There are millions of hours of experience with current configurations - when you start to change the configurations, you need to put a lot of money into test time to prove that you haven;t reduced reliability. Guys have done much of what you suggest in the racing world - and they have the engine-out landings to prove it/. Not that you can't make those technologies reliable - but the development costs will be high.

And that brings us to the other point - amortizing the development costs. There are just no economies of scale. you're not going to sell millions to spread the costs around - you're going to sell thousands - so the development costs are spread over very few units. And homebuilders are nothing if not , ahem...thrifty....shal we say....
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  #40  
Old 03-21-2012, 03:43 PM
David-aviator David-aviator is offline
 
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Quote:
Originally Posted by bret View Post
I should have been more clear in my first post, I am not a fan of auto engines in aircraft, I was thinking of ways to improve the Lycoming base engine, like head design, most engines, gas and diesel use 4 or 5 valves, roller rocker arms with correct geometry to reduce valve tip side load, compression chamber design. Tuned intake runner dia. and shape to match the speed of the incoming air to utilize air mass for inertia supercharging. Tuned exhaust for max cylinder scavenging, I think 4 into 2 into 1 works well. Piston oil sprayers to cool the piston. A fuel system that atomizes the fuel better and delivers the fuel timed with the intake valve events. ect.....
The improvements you mention are appropriate with modern engines running at 6000 rpm.
But with a direct drive at 2700 rpm, the room for increased performance is limited. There is some demonstrated performance improvement doing what suggest if you want pay for it. BPE, for example, did their standard balancing of parts a few other things resulting in 187 hp vrs 180.
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