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  #21  
Old 11-05-2013, 10:38 AM
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Michael White Michael White is offline
 
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Location: Cartersville, Georgia KVPC
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Quote:
Originally Posted by flyboykelly View Post
The engine is 3600cc, 150 hp, 275 lbs dry, 33" diameter. If you look at the specs from lycoming on their O-320, there is virtually no difference. The biggest difference is in displacement.
And frontal area.

I think you're adding more frontal area than you might suspect (that whole pi-R-squared thing with the round cowling), and I'm afraid there might be a somewhat large speed penalty in the end. I hope not, but it keeps nagging at me as I follow your progress.

Not meant as criticism, just stating something you may already have thought of and accounted for. Didn't see it mentioned on your web page, though I may have missed it. My hat is off to you for taking the leap to do this, and for taking the time to engineer it properly. Can't wait to see pictures and first flight write-up.
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  #22  
Old 11-05-2013, 11:55 AM
rv7charlie rv7charlie is offline
 
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Isn't frontal area measured on the entire airplane; not just the engine? I don't see that much difference.

I would think that the bigger question is cooling drag. Even there, I'm not sure the radial has to be that much worse (could be better than a flat engine).

Charlie
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  #23  
Old 11-05-2013, 01:15 PM
Aryana Aryana is offline
 
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What a fantastic idea. I think you will have something really enjoyable when it's flying. I can't wait to see pictures of it hung on the airframe.
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  #24  
Old 11-05-2013, 05:32 PM
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flyboykelly flyboykelly is offline
 
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Default Airframe drag

Michael,

Airframe and cooling drag are definately considerations that I have tried to address. The engine will be fully baffled and a large spinner will be used. Also I have a baffle aft of the engine to smoothly exit the air. I'm hopeful of low cooling drag in this configuration, but testing will tell. Try to think of Rare Bear, but without such a small cooling gap.
BTW I love constructive criticism. The wealth of knowledge on this forum keeps us all safe.
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  #25  
Old 11-05-2013, 05:59 PM
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Eddie P Eddie P is offline
 
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Location: Aptos, CA (previously Reno, 21 years!)
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What a great project, I look forward to seeing more! I like the idea of a large spinner, it will probably make a big difference on the efficiency of a good cooling system with minimum drag.
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  #26  
Old 11-05-2013, 06:08 PM
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L.Adamson L.Adamson is offline
 
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Simply Awsome!!!!

Love the looks of that radial.
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  #27  
Old 11-05-2013, 06:13 PM
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Kevin Horton Kevin Horton is offline
 
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I?ve got a very soft spot for round engines, as I spent several years herding a pair of R-1820s around, flying CP-121s (known as S-2s in most parts of the world). Those big, bad dogs had over 200 cu inches per cylinder! Loud too, especially during during take-off with 53? HG of manifold pressure at 2800 rpm. The first couple of attempts to start them were fun, as it felt like you were going to run out of hands and fingers to manipulate all the switches, levers, etc in the right sequence at the magic moments.
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  #28  
Old 11-05-2013, 10:04 PM
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grayforge grayforge is offline
 
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Isn't a Turbine engine also Round? :-)
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  #29  
Old 11-06-2013, 09:27 AM
jrs402 jrs402 is offline
 
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I would say turbines are more tubular. Is that a word?
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  #30  
Old 11-06-2013, 10:01 AM
jbDC9 jbDC9 is offline
 
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Quote:
Originally Posted by Kevin Horton View Post
I?ve got a very soft spot for round engines, as I spent several years herding a pair of R-1820s around, flying CP-121s (known as S-2s in most parts of the world). Those big, bad dogs had over 200 cu inches per cylinder! Loud too, especially during during take-off with 53? HG of manifold pressure at 2800 rpm. The first couple of attempts to start them were fun, as it felt like you were going to run out of hands and fingers to manipulate all the switches, levers, etc in the right sequence at the magic moments.
S-2's man, I'm jealous! I've always wanted to fly one of those... but I'm making do instead by flying a CAF Lockheed Lodestar, also with a pair of R-1820s. And starting the engines is (almost!) the best part... like you said, the first few starts were pretty clumsy as you learn all the multiple switch and lever motions, but once you get it figured out, it's a hoot! I just love the sound, sight and smell of these things coughing to life.

Too bad there's no Smell-a-vision for the fuel/oil smoke...
http://www.youtube.com/watch?v=vbH0drUhFKc
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