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  #11  
Old 03-21-2012, 05:18 AM
WingsOnWheels WingsOnWheels is offline
 
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Location: Plano, TX
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Quote:
Originally Posted by tjo View Post
There is new technology I would like to see on a Lyc, but make no mistake, a Lyc is not low tech, nor is it stuck in the dark ages.

Tim
Very well said. If you look at the BSFC of the Lycon vs most auto engines, the Lycon is very close. Our air-cool engines may look antiquated, but they generally out perform most auto engine on a power to weight ratio. Torque is king in aviation engines. The O-360 should be putting out around 350ftlbs or torque up to 100% continuous, for ~2000 hours or as much as 400,000 miles in the RV (at WOT 200mph Cruise).

That said, if there were a diesel out there with the same power-to-weight and well proven, I would mount one instead of the lycoming. I would love to have a diesel on my plane.
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  #12  
Old 03-21-2012, 06:44 AM
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rzbill rzbill is offline
 
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Location: Asheville, NC
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Quote:
Originally Posted by bret View Post
couldn't we go to a shorter Dia prop and go with a 4 or 6 blade?
In general terms, prop efficiency is best when there is very little increase in airsteam velocity across the prop disc. With that in mind, in order to get the thrust required for the application, the diameter of the prop disc must go up and the rpm must go down to avoid tip shock.

Another way to look at the velocity comment is to compare the prop to a wing. When one is creating a lot of downwash on a wing (read prop airstream delta V), the induced drag is very high. On a prop, the induced drag sucks HP and lowers prop eff.
Just like a wing, one wants to operate a prop in the best L/D part of the polar.
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Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 850 hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'... Eyeballin' vinyl really hard.
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  #13  
Old 03-21-2012, 06:56 AM
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flywithme623 flywithme623 is offline
 
Join Date: Dec 2011
Location: Somerset VA
Posts: 77
Default Diesel????

Why is nobody talking about smooth reliable aero diesel engine. Can't beat there economy, there reliability, start up at low temps like no other.

I've been flying diesels of and on for the last three years. No greater joy when it comes to endurance.

That is my dream for my -8 as soon someone can do it for a better price....that's the only down-side.
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Michael Zimmermann

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  #14  
Old 03-21-2012, 07:29 AM
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rocketbob rocketbob is offline
 
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There is a big thing ignored here, and that's the efficiency of a powertrain system as a whole. Cars have averaged 25mpg since the early 80's. Coupled to a transmission, drive shafts, half shafts, etc. the system is very inefficient. On the other hand a propeller is fairly efficient, and that is where we make up for engine deficiencies. So the systems as a whole are pretty good, but there is a lot of room for improvement particularly in the intake system and cylinder head design.
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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #15  
Old 03-21-2012, 07:42 AM
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bret bret is offline
 
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I disagree on the 25 MPG, Honda I DTEC 2.2 Diesel is getting 63 MPG, one of their improvments was to inject the fuel at 1,600 BAR, thats 23,000,000 PSI, our comon rail systems are at around 30,000 PSI
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  #16  
Old 03-21-2012, 07:45 AM
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flywithme623 flywithme623 is offline
 
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Now we are talking diesel!!!
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Michael Zimmermann

RV-8 Sold

Happy people don't necessarily have the best of everything,
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  #17  
Old 03-21-2012, 07:51 AM
krw5927 krw5927 is offline
 
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Location: Wichita, KS
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Quote:
Originally Posted by bret View Post
I disagree on the 25 MPG, Honda I DTEC 2.2 Diesel is getting 63 MPG, one of their improvments was to inject the fuel at 1,600 BAR, thats 23,000,000 PSI, our comon rail systems are at around 30,000 PSI
1600 bar is about 23,000 PSI.
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  #18  
Old 03-21-2012, 07:57 AM
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rocketbob rocketbob is offline
 
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Quote:
Originally Posted by bret View Post
I disagree on the 25 MPG, Honda I DTEC 2.2 Diesel is getting 63 MPG, one of their improvments was to inject the fuel at 1,600 BAR, thats 23,000,000 PSI, our comon rail systems are at around 30,000 PSI
Fleet average is still around 25mpg. My Golf TDI gets 48mpg and is ten years old. The Honda DTEC is not available in the USA.
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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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  #19  
Old 03-21-2012, 08:51 AM
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airguy airguy is offline
 
Join Date: Oct 2006
Location: Garden City, Tx
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I love all the "I get XX MPG" statements without any information about the weight of the vehicle. Completely meaningless.

If you want to get into real meaningful data, let's talk about BSFC and ton-miles travelled per gallon.
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Garden City, TX VAF 2020 dues paid
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Built an off-plan RV9A with too much fuel and too much HP. Should drop dead any minute now.
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  #20  
Old 03-21-2012, 09:01 AM
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PerfTech PerfTech is offline
 
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Location: Redlands, Ca.
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Default Why?

This is very simple and can be summed up in one word!
.
LAWYERS!!!!!!!!
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