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  #1  
Old 04-12-2010, 01:04 AM
Marc Oppelt Marc Oppelt is offline
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Default Progress (I think)

Making some progress
I think...
Here's some pictures-
click on the link.

http://picasaweb.google.com/oh.u8it2/LongEZProject#
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  #2  
Old 04-12-2010, 01:23 AM
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mfryer mfryer is offline
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Default Re: Progress (I think)

Looks good. Having the fuselage in that stage is a nice milestone.
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  #3  
Old 04-12-2010, 01:30 AM
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Dennis Passey Dennis Passey is offline
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Default Re: Progress (I think)

Looks great!
I particularly like your finished engine! Glad that is out of the way!=)
There is a pretty interesting article on a Velocity with a V8 in it in this months EAA rag.
BTW, How did the fishing run go this last time?
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  #4  
Old 04-12-2010, 12:15 PM
Marc Oppelt Marc Oppelt is offline
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Default Re: Progress (I think)

Thanks. I plan to stick the tub together this week while the weather is crap and I can't work outside.

I have the article in the rag by my bed. I joined EAA just to get that article. I plan to use a similar engine, but direct drive rather that using a reduction. I only need 300hp at 3500rpm.

Fishing was OK. We had caught almost all of our allotted quota in the Aleutians by the time I left the boat. There is plenty of fish out there.
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  #5  
Old 04-12-2010, 11:18 PM
argoldman argoldman is offline
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Default Re: Progress (I think)

Quote:
Originally Posted by Marc Oppelt View Post
Making some progress
I think...
Here's some pictures-
click on the link.

http://picasaweb.google.com/oh.u8it2/LongEZProject#

Marc,

Fortunately you have a while before you choose an engine and cooling system. The engine installation,in the photo, that you show, will probably have severe cooling problems. Not necessarily because of the radiator size.

The cooling air is brought to the radiator with a wedge plenum--Good. But before it gets to that plemum it must take a 90 degree turn--- bad (resistance). After that 90 degree turn, the plenum will cause it to do another 90, but because of turbulence created there, and the wedge shape what is left of the air flow will go through the rad somewhat evenly and for the amount of air,will cool well. However, after it exits the radiator, it goes slam into the back of the engine and other things metallic, plastic, and paper. Very bad.

Air does not do what intuitively we think that it will. Although we think that it will easily go from high pressure to lower pressure, any obstruction on the exhaust side of the radiator, within a certain distance will cause the air to, in effect stop and make cooling ineffective at that place in radiator since the air going through the fins, effectively stops. When air at the cooling air enterance hits the right resistance, (created, in this case by the first 90 and the proximity of the engine to the exhaust of the radiator (added to the resistance through the radiator), it will spill over the intake in a process called external diffusion, which apparently does not cause as high a drag as one would imagine but gives no cooling .Makes no logical sense, so you will have to ask Kuchemann and Weber. Aerodynamics of Propulsion, McGraw-Hill, 1953 LOC 52-6541

Perhaps I am misreading or misinterpreting their work. In my own work with my liquid cooled dragonfly, I quickly learned that what makes logical sense and what the air thinks, in its flowage, are not necessarily the same. Thus the observation that many (possibly most) homebuilts have initial cooling problems (liquid or air cooled).

Some of these problems may be mitigated by proper design of the cooling air exhaust or the inclusion of augmenters, however off hand, I see big problems.

Other than that, the installation looks cooool

I am currently designing and building my cooling system for my Renesis. Hopefully I have designed out most of the negative factors. We will see.

Wait until that airplane flys and cools well. Then copy what works, not what you see as a mock-up.
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  #6  
Old 04-13-2010, 12:17 AM
Lynn Erickson Lynn Erickson is offline
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Default Re: Progress (I think)

Quote:
Originally Posted by argoldman View Post
Marc,

Fortunately you have a while before you choose an engine and cooling system. The engine installation,in the photo, that you show, will probably have severe cooling problems. Not necessarily because of the radiator size.

Wait until that airplane flys and cools well. Then copy what works, not what you see as a mock-up.
I think the V8 engine in the picture is a mock up is for a tractor airplane. the exhaust seems to be exiting under the firewall facing away from the prop. the high pressure air would go around the engine and then through the radiator. I believe that the picture is Bill Gipson's RV 10
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Last edited by Lynn Erickson : 04-13-2010 at 12:32 AM.
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  #7  
Old 04-13-2010, 01:01 AM
Marc Oppelt Marc Oppelt is offline
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Default Re: Progress (I think)

Uhhh....well, that mockup hanging there is for an RV10, which has the prop on the other end and so cooling is all different. I just threw that picture in there because I like to see a V8 with a prop attached. I think its a better engine than those thrasher lycomings, so thats what I'm going to use. In fact, seeing Gary Spencer's plane with the Ford V8 in it was what finally got me building my own plane.

And yeah, alot of people fly with Lycomings and get there and all that...but just today a local Long-EZ pilot was telling me about his Brock mount cracking and turning back to the field after the plane started shaking like hell. He landed with two bolts holding the engine on. Bad enough that my Harley tries to shake itself apart...but I don't need my plane doing that.

I don't have the cooling figured yet...but I'll cross that bridge when its time. I do know that you need to slow down the air to get it to bend around corners and absorb heat properly, and that P-51 scoops tend to work better that NACA ducts. I've read some stuff and have more to read.

Right now I'm just making a tub.
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  #8  
Old 04-13-2010, 01:55 AM
Marc Oppelt Marc Oppelt is offline
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Default Re: Progress (I think)

Lynn - I think you and I were typing at the same time. I think you are right about that guys RV 10, and I also think that's the one they bellied in after gliding back to the airport when the engine heated up and went into "Limp Home" mode.

Apparently they could have disabled the lime mode with EFI tuning software but didn't. Oops. Too bad; that was a beautiful plane.
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  #9  
Old 04-13-2010, 02:12 PM
argoldman argoldman is offline
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Default Re: Progress (I think)

Quote:
Originally Posted by Marc Oppelt View Post
Uhhh....well, that mockup hanging there is for an RV10, which has the prop on the other end and so cooling is all different. I just threw that picture in there because I like to see a V8 with a prop attached. I think its a better engine than those thrasher lycomings, so thats what I'm going to use. In fact, seeing Gary Spencer's plane with the Ford V8 in it was what finally got me building my own plane.

And yeah, alot of people fly with Lycomings and get there and all that...but just today a local Long-EZ pilot was telling me about his Brock mount cracking and turning back to the field after the plane started shaking like hell. He landed with two bolts holding the engine on. Bad enough that my Harley tries to shake itself apart...but I don't need my plane doing that.

I don't have the cooling figured yet...but I'll cross that bridge when its time. I do know that you need to slow down the air to get it to bend around corners and absorb heat properly, and that P-51 scoops tend to work better that NACA ducts. I've read some stuff and have more to read.

Right now I'm just making a tub.

Yea,

What Goldman (me) said before but even worse. The fact that you have a big fan up there means little to air that has it's own mind.

In the tractor configuration, the air in the pressurized area (cowl) squirts around all the stuff, makes a series or right (or left (90 degree) turns, then through the radiator where it immediately must make two more almost right turns until the exit. Looks good but my original statement still stands.

It seems like the designer of this cooling system has taken parts of efficient cooling systems and has reversed them.

The wedge shape plenum must be on the high pressure side of the radiator. You do create some pressure loss as the air turns 90 degrees and the wedge shape helps to even the pressure over the face of the radiator (as it wants to bunch up at the far end and ignore the near end). This creates turbulence which helps in the cooling. In this configuration (tractor) the air exits the radiator smack into a wall, very small at the top, insufficient at the bottom (exactly opposite of what is required) and then is expected to turn 90 degrees and then another 90 degrees into the arstream. Exceedingly high potential resistance. Yes, air will always go from high to low pressure, however it will also always go the path of least resistance, which many times is completely around the intake.

Would that things would be so easy. Why didn't the mustang just extend the cowl a little, slip a radiator in and call it a day, especially with the slim engine they were using.. rather than all of the plumbing, weight, and vulnerability of the radiator being placed in the hinterlands. Certainly W&B was probably a factor, but just think of that huge prop pumping away pieces of air. I guess that they just wanted it to cool well

Certainly, we are free to design as we want, however copying an untried cooling system, on a mock-up, which frankly goes against some relatively well researched fluid mechanics (ref reference in my last post), one must tread lightly.

In my personal experience, with a tractor aircraft, Putting the radiator at 45 degrees to the firewall, at the firewall, and baffeling it well so that air could only escape the cowl, through the radiator, a cooling air intake of appropriate size near the prop (removed from the dead area of the hub), (in too many respects similar to that RV example) flight experience and later tufting, showed virtually no airflow through the system. How could that happen? Shocked the hell out of me as it seemed so right. Engine consistently overheated, blew out all of it's coolant in one circuit ----multiple times ----- with airflow changes between each flight.

The next iteration after much anguish and a little study, reduced the radiator to 1/4 the size of the original (granted it was then aluminum) through specific ducting, both in and out, with a small cowl flap, it kept the engine happy.

The cooling system doesn't know if the breeze is coming from a prop, or from the forward motion of the aircraft (when in flight). The air just does it's own thing, based on fluid mechanics, not on what we think it will do. Again my statement of cooling problems with homebuilts.

I applaud your consideration of alternative engines (I am of the same ilk). I just want you, and others to be aware of the obstacles to overcome. There is no need to reinvent the wheel here. I know you are just in the fuselage stages here, and all is very exciting, but understanding some concepts, long before you need them may prevent you from having to do retrofitting and redesigning later.
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  #10  
Old 04-13-2010, 03:01 PM
Marc Oppelt Marc Oppelt is offline
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Default Re: Progress (I think)

Well, you can see at a glance that the cooling system in the picture I posted is far from ideal. No big secret there. I wouldn't waste my time with anything like that.

I just posted that picture because it has a V8 and a prop. I like both of those things.

Also, its really shiny... and I like that too.

Ok, I gotta get back to work or I'll never get this doggamn thing done.
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  #11  
Old 04-13-2010, 04:23 PM
argoldman argoldman is offline
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Default Re: Progress (I think)

Quote:
Originally Posted by Marc Oppelt View Post
Well, you can see at a glance that the cooling system in the picture I posted is far from ideal. No big secret there. I wouldn't waste my time with anything like that.

I just posted that picture because it has a V8 and a prop. I like both of those things.

Also, its really shiny... and I like that too.

Ok, I gotta get back to work or I'll never get this doggamn thing done.
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  #12  
Old 04-13-2010, 05:37 PM
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Dennis Passey Dennis Passey is offline
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Default Re: Progress (I think)

..." it's really shiney...and I like that too".
Man, I agree with you it's a nice looking engine. I like shiney too. The nickname "crow" would fit nicely here.
I want shiney engine bits to put in my nest!
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Old 04-13-2010, 11:51 PM
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mfryer mfryer is offline
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Default Re: Progress (I think)

Quote:
Originally Posted by Marc Oppelt View Post
...but just today a local Long-EZ pilot was telling me about his Brock mount cracking and turning back to the field after the plane started shaking like hell. He landed with two bolts holding the engine on.
Marc, can you share with me who the local Long-EZ pilot was? Did he make any modifications to the mount to prevent the problem from happening again?
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  #14  
Old 04-14-2010, 01:07 AM
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Dennis Passey Dennis Passey is offline
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Default Re: Progress (I think)

Buy a mount from the Cozy Girrrlz. I did. Man I have one stout mount with extra gussets and awesome welds.
A-1 workmanship.
Maybe a good idea to not powdercoat the mount as they suggest, due to the powdercoats thickness maybe hiding a developing weakness or crack.
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  #15  
Old 04-14-2010, 03:31 AM
Marc Oppelt Marc Oppelt is offline
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Default Re: Progress (I think)

Yeah, Martin...I was thinking about you when he was telling me about this, because thats the same mount you have, no? He sent it back to Brock and had it reinforced. You could get a picture of a reinforced mount like yours and then take it down to Zieglers downtown. They can weld that thing up no sweat, and probably have it stress-relieved too. I'm guessing thats why these mounts crack; there are lots of motorcycle frames out there made of the same material and they see alot of vibration and usually never crack. Bike frames are stress-relieved after fabrication - very important step in the process.

The local pilot is the guy I met last summer at the fly-in. I got ahold of him, and I'm going to hook up with him soon...maybe today even. I told him about you, and he was very interested. It sounds like one of his friends here in town is building a Long-EZ and is at about the same build stage as you are. This could get interesting.

We'll talk soon.

Last edited by Marc Oppelt : 04-14-2010 at 03:40 AM.
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