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  #271  
Old 12-30-2009, 09:38 PM
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pilotjt pilotjt is offline
 
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Quote:
Originally Posted by DanH View Post
Slow but sure.



Geez Dan.... Just plain ole' Awesome! Nice meeting you at the Rhodes/Taylorsville Fly-In BTW..
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  #272  
Old 12-31-2009, 11:36 AM
Calvin25 Calvin25 is offline
 
Join Date: Jan 2009
Location: PHX, AZ
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One of the nicest RV's on here and it doesn?t even have wings on it! Dan never hesitate to give up dates as I?m sure im not the only one that is inspired by them.

Every detail I see from your plane shows all out perfection. Except that motor looks like something you would get from a second hand lawn mower shop
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  #273  
Old 01-01-2010, 09:14 AM
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Location: 08A
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Thanks guys. Bunch of experiments going on here. The primary is the large, external diffusion low velocity inlets; I'm shooting for maximum pressure recovery and hope to maintain maximum exit velocity.

Tweaks include relocating the inlet centers to about 1.5" above the crankshaft plane. They also move outboard, a natural consequence of switching to round inlets. The relocation improves the duct shapes in the vertical; more of a straight shot rather than the typical steep ramps. It should also reduce flow reversion because external pressure at the inboard sides of the inlets should be increased compared to stock slot inlets.

Although low velocity (the system is exit throttled) there is certainly some intake velocity, so internal divergent angles remain important. In this case it mostly drives the shape of the ducts and forward plenum wall nearest and above the crankshaft. The shapes there are not perfect, merely reasonable and better than box shapes. The left inlet had to accomodate the prop governor. NASA 3405 suggests some recovery loss because of a governor in the intake. I faired this one into the duct wall with a urethane collar gasket, but the head still protrudes into the intake flow. Again, not perfect but maybe better.

You can probably start an argument in an aero geeks bar (anybody having visions of a Gary Larson cartoon?) regarding plenum volume. I vote for large volume, and this one more or less mimics the inside of the upper cowl. However, it doesn't look large (and it's not) because this is all the available space when you shove a big angle valve motor into an RV-8 cowl. The front and rear upper corners on the left side are really tight; note the one-piece bent valve cover baffles on that side. I even rounded the mounting lugs on the cylinders in order to lower that side away from the inner cowl surface.



What looks like duct tape on the cylinder face is actually fiberglass cloth impregnated with Loctite 598. All the cylinder baffles are lined with this "gasket" and every other gap is sealed. The only air path out of this plenum is between fins.



The remote oil cooler mount is much like one I did on a previous project for a friend. Worked very well. 4" duct, not 3", and again some care in smooth transition between the round duct and the rectangular oil cooler face. The black transition is glass; I outlined how to make duct parts in another thread (http://www.vansairforce.com/communit...ad.php?t=44856). This one is ducted all the way to the cowl exit.



I am not suggesting you do any of these things, and you certainly don't need to do any of these things. They are experiments to suit my personal fancy. Hopefully they will add both speed and operational advantage....but they may be just a waste of time. We'll see
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Last edited by DanH : 01-29-2010 at 01:42 PM.
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  #274  
Old 01-02-2010, 06:31 PM
Andy_RR Andy_RR is offline
 
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Dan, great to see someone thinking and experimenting (and quoting NASA3405!) with cooling airflow. I wish you good speed with your mods. Nice work!
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  #275  
Old 01-02-2010, 06:56 PM
chaskuss chaskuss is offline
 
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Quote:
Originally Posted by DanH View Post
snipped
The remote oil cooler mount is much like one I did on a previous project for a friend. Worked very well. 4" duct, not 3", and again some care in smooth transition between the round duct and the rectangular oil cooler face. snipped This one is ducted all the way to the cowl exit.



snipped
Dan,
How about a photo showing how the oil cooler's exit duct blends into the cowl's exit airstream? Your workmanship is outstanding. One other question. Why did you install the oil cooler in a vertical position? Lack of space? It seems that you would have achieved better airflow by orienting the oil cooler at an angle. Then you would not have forced the air to make 90 degree changes of direction going into the oil cooler.
Charlie Kuss
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  #276  
Old 01-02-2010, 10:27 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by chaskuss View Post
Dan,
How about a photo showing how the oil cooler's exit duct blends into the cowl's exit airstream? Your workmanship is outstanding. One other question. Why did you install the oil cooler in a vertical position? Lack of space? It seems that you would have achieved better airflow by orienting the oil cooler at an angle. Then you would not have forced the air to make 90 degree changes of direction going into the oil cooler.
Charlie Kuss
Exit area isn't finished yet; more on that later. Some of the parts are here: http://www.vansairforce.com/communit...25&postcount=1

Yes, I could have turned the cooler, but then the mount would be complicated. This mount is light and dead simple. I suspect I'll need to choke the cooler flow anyway. (Postscript Jan 2012: Nope...I could use more oil cooling. Charlie may have been right, don't know yet.)

Planning, Jan 2009:



Grab the saw, take a deep breath...



Result, Jan 2010:

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Last edited by DanH : 12-10-2014 at 05:00 AM.
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  #277  
Old 01-04-2010, 08:12 AM
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DanH DanH is offline
 
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Charlie asked about the exit.

Exit bell, early fabrication:



The cooler dumps into what should be a high velocity/low pressure area. (Postcript, Jan 2012: By measurement, pressure at the cooler outflow is 2"~3" H2O higher than exterior static.) You can see the duct (black) above the tailpipe.



I built the cowl with nutplates so I could swap exit panels at will and thus vary exit area (just four screws in it here).



Made two panels to start. This is the big exit area panel.

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Last edited by DanH : 12-10-2014 at 05:04 AM.
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  #278  
Old 01-04-2010, 12:13 PM
chaskuss chaskuss is offline
 
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Default Wow!

Quote:
Originally Posted by DanH View Post
Charlie asked about the exit.
snipped
The cooler dumps into what should be a high velocity/low pressure area. You can see the duct (black) above the tailpipe.
snipped
Hopefully, that should give your oil cooling exit a scavenging affect, sort of like your 4 into 1 exhaust. What oil cooler are you using?

Quote:
Originally Posted by DanH View Post
snipped
Very shiny! Everything reflects nicely. Did you make the exhaust ramp from stainless steel, like I did? Or has the aluminum ramp been polished?
I really wanted a 4 into 1 exhaust. However, my choice of an 8A makes that very difficult. I would have to develop a prototype for the exhaust company. I'm not sure that I could get equal length runners, without making installation/removal VERY difficult.
Charlie
PS What made you decide to place the oil cooler on the right side, as opposed to the left side where Vans puts it? Control cable interference?

Last edited by chaskuss : 01-04-2010 at 12:18 PM. Reason: Added PS & removed the 6th sentence.
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  #279  
Old 01-04-2010, 01:01 PM
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DanH DanH is offline
 
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Quote:
Originally Posted by chaskuss View Post
What oil cooler are you using?
10599R

Quote:
Did you make the exhaust ramp from stainless steel, like I did?
Yes, the external ramp is polished stainless.

Quote:
I really wanted a 4 into 1 exhaust. However, my choice of an 8A makes that very difficult.
If this were an -A, I'd have eliminated the stock exit scheme entirely and explored dual exhausts and outlets. Consider the current best Legacy projects:

http://www.aerochia.com/kits_Legacy_speed-cowl.html

Wasn't Mr. Vetterman playing with dual outlets also?
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  #280  
Old 01-04-2010, 04:25 PM
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rv7boy rv7boy is offline
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Default Link for NASA document

In case anyone wants to read the document Dan refers to, here is the link. You can also Google "NASA-CR-3405" and find it.
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