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  #31  
Old 11-22-2012, 03:21 PM
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schristo@mac.com schristo@mac.com is offline
 
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Default first flight report... bone dry

A thanksgiving morning test flight filled with enough aerobatics to make my head spin... the belly is completely dry and is literally 'squeaky' clean. Glad that I did this BEFORE eating turkey!

I am looking forward to more extensive testing but the initial report is very positive, especially given the round loops with a .5 gee float at the top. After I get some more time of typical flight and light aero to observe the belly I will push some short zero / mild negative gee excursions to see what gets spit out.

Hope that we can get some meaningful real world performance data on adding the vacuum valve.
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RV7 powered by a lycoming thunderbolt IO-390
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Last edited by schristo@mac.com : 11-22-2012 at 06:09 PM.
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  #32  
Old 11-22-2012, 04:39 PM
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Default

Quote:
Originally Posted by Wayne Gillispie View Post
I get a 20-25F drop in water boiling point at cruise altitude.
The exhaust-driven evacuator holds case pressure 2~3" below ambient, i.e. boiling point 3~5 degrees F lower than normal for that altitude.

Quote:
Originally Posted by schristo@mac.com View Post
Hope that we can get some meaningful real world data on adding the vacuum valve.
Ummmm....what exactly do you want to know?
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  #33  
Old 11-22-2012, 05:34 PM
Tom Martin Tom Martin is offline
 
Join Date: Jan 2005
Location: Ontario, Canada
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Default

First, my apologies regarding the quality of the following picture but it is relevant to the discussion.

This is how I collected the oil from my separator for the 50 hour test period. Although the poor picture makes the oil look murky you will just have to take my word for it that it was clean oil, no residue, no water, and no yellow sludge.
I have seen yellow sludge in old farm equipment, neglected auto engines, garden tractors etc but I run about 100 to 120hours a year in my rocket and change the oil every 25 hours. Under those conditions the oil stays pretty clean. If you only fly 25 hours a year and change the oil once then YMMV. The oil sample was drained every once in a while and placed in a separate container. Nothing settled out with time, three to four months.

The black tube that you see is my crankcase breather hose outlet. In this location I measured a -2" ambient pressure drop in the crankcase. I placed the outlet in various locations until I got this minus 2 number. This was done using a water manometer with a fitting on the dip stick cap. Prior to this the breather was dumped directly on to the exhaust pipe, in the cowling area, as most RVs do. In that location the crankcase had a 1" POSITIVE pressure. All my little engine oil leaks disappeared when I moved the vent 2" aft of the cowling (4" aft of the firewall)
Maybe there is a reason why most of the certified aircraft dump their crankcase vent to the exterior of the cowling.....

I am posting this with some reluctance as I have been challenged with this information in the past. Generally speaking it is frowned on to suggest that what Van recommends may not be correct. Most of the time the company is spot on, say 99%of the time. If you disagree with me show me your test information, and we can have a discussion. I may be wrong 99% of the time but I am pretty confident about this 1%!



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Last edited by Tom Martin : 11-22-2012 at 05:37 PM.
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  #34  
Old 12-17-2012, 01:32 PM
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PerfTech PerfTech is offline
 
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Location: Redlands, Ca.
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Talking Oil Return All Good!!!!!

....We have been watching this thread develop and decided to chime in. The question of returning nasty by products to the engine is not what actually takes place. The water or moisture based by-products of combustion that are airborne in the breather line are not separated out by our unit. They remain airborne and exit overboard just as before. All modern engines manufactured after about 1970 are sealed crankcase engines without an external breather. The crankcase fumes are routed into the intake and consumed via the PCV valve or inlet of the throttle body. This is not acceptable for aircraft due to possible freezing issues in the air inlet. The automobiles you drive to the airport do not have a road draft tube or external breather pipe (left over from the 1920's design). All modern engines have built in oil separators and much care is taken to see that they do their job and do not blow oil into the intake stream, out on the ground or bottom of the car. To say that the trail you leave is a necessary indicator of engine health is not the case. Modern engines go 6 to 8 thousand miles between oil changes, the oil stays very clean and adding oil between changes is almost non existent. If one develops an engine problem you will know by the oil burn, pressure, performance etc. not by the filth on the belly or your hanger floor. I suppose if one kicks out a quart or two each flight you will never need to change the oil. These units are the finest quality available in workmanship, materials and design. If you find any condition to the contrary or are not happy with the product we will refund no questions asked. We began producing separators for the VariEze and other Burt Rutan creations in 1978 then offering to all other experimentals. We also began to manufacture separators for certified aircraft and aircraft with wet vacuum pumps shortly there after. This isn't new or rocket science, thousands are in aircraft use all over the world. Millions on automobiles and other equipment as well. We have yet to find an unhappy customer. Several hundred RV owners have installed them and not one bad report on this or any other forum. Anyone with questions is welcome to give us a call and we will be happy to answer your concerns. Thank you and merry Christmas to all here on the forums. Allan...
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  #35  
Old 12-17-2012, 04:23 PM
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PerfTech PerfTech is offline
 
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Default

Quote:
Originally Posted by schristo@mac.com View Post
A thanksgiving morning test flight filled with enough aerobatics to make my head spin... the belly is completely dry and is literally 'squeaky' clean. Glad that I did this BEFORE eating turkey!

I am looking forward to more extensive testing but the initial report is very positive, especially given the round loops with a .5 gee float at the top. After I get some more time of typical flight and light aero to observe the belly I will push some short zero / mild negative gee excursions to see what gets spit out.

Hope that we can get some meaningful real world performance data on adding the vacuum valve.
.
...We are glad to hear you are having good results with your separator and system. We also want to say thank you for posting and stating your opinion. In talking about power gains on our dyno we see about 5 to 8 HP on a typical 180 lycoming at full throttle. This seems to fall in line with the reports we get back from pilots after the installations. We included below a few links to information on the subject of vacuum in the crankcase and power gains. There are virtually hundreds of sites and discussions on the subject as this is accepted practice in all types of racing for efficiency gains. Thanks, Allan...
.
http://nutterracingengines.com/racin...uum_facts.html
.
http://www.competitionproducts.com/M...uctinfo/22642/
.
http://speedtalk.com/forum/viewtopic...=32881&start=0
.
http://www.team-integra.net/forum/15...uum-pumps.html
.
http://www.dragstuff.com/techarticles/vacuum-pumps.html
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AntiSplatAero.com
Innovative Aircraft Safety
Products, Tools & Services
Info@AntiSplatAero.com
Southern California (KREI)
RV-9A / Edge-540
(909) 824-1020
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  #36  
Old 12-18-2012, 06:11 AM
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dlloyd3 dlloyd3 is offline
 
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Location: Locust, NC
Posts: 440
Default air oil separator

A few months back I installed one of Allan's oil separators and check valve. I am very satisfied with the quality of construction, instruction and hardware provided. Like others, a small oil leak at the back of the engine seems to have gone away. Allan asked at the time if I saw any performance increase. Nope. More flying and a little testing have shown my top speed at 8000' density altitude to be 179 knots. Phase One testing was 177 knots. Pretty darn close but a 5 horsepower improvement would provide only about that difference. 5 Horsepower would also give another 100 FPM climb. Is it there? Can't say, don't know if my Phase One testing was accurate to within 100 FPM. One thing for certain is the airplane now has a much cleaner belly.
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  #37  
Old 12-18-2012, 06:12 PM
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Snowflake Snowflake is online now
 
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Default

Where does the crankcase vacuum valve go? In between the breather port and the separator? Just trying to understand how that works...
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1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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  #38  
Old 12-18-2012, 08:10 PM
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Quote:
Originally Posted by Snowflake View Post
Where does the crankcase vacuum valve go? In between the breather port and the separator? Just trying to understand how that works...
Tail end of the system, about 3" from the exhaust header, lower left below...

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Last edited by DanH : 12-18-2012 at 08:14 PM.
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  #39  
Old 12-20-2012, 09:38 AM
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smokyray smokyray is offline
 
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Default Been there done that...

Quote:
Originally Posted by Aryana View Post
Why not just run the breather tube through the fuse all the way out to the back of the plane?
Good Idea AA,
In fact it was in the original Pitts plans back in the 1950's to set up a rudimentary air/oil separator using just that technique. Many older Pitts still keep an old pork&bean can hanging under the tail tube for the remnant oil to drip in while parked.
When Curtis Pitts met my friend Jim Swick, Jim had designed one of the early inverted fuel/oil systems for Frank Price's Bucker. Curtis liked it and Jim built one for him. Frank Christen scoped it out at an airshow, sat down at his drawing board and the rest is history.
I have installed three Slime Fighters with excellent results. I fly aerobatics pretty much every time I strap my RV on and it does help for the occasional suare' into negative G flight. http://www.aircraftspruce.com/catalo...s/slimeftr.php

V/R
Smokey

Last edited by smokyray : 12-20-2012 at 09:43 AM.
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  #40  
Old 12-20-2012, 10:22 AM
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JonJay JonJay is offline
 
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Location: Battleground
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Default

Quote:
Originally Posted by smokyray View Post
Good Idea AA,
In fact it was in the original Pitts plans back in the 1950's to set up a rudimentary air/oil separator using just that technique. Many older Pitts still keep an old pork&bean can hanging under the tail tube for the remnant oil to drip in while parked.
When Curtis Pitts met my friend Jim Swick, Jim had designed one of the early inverted fuel/oil systems for Frank Price's Bucker. Curtis liked it and Jim built one for him. Frank Christen scoped it out at an airshow, sat down at his drawing board and the rest is history.
I have installed three Slime Fighters with excellent results. I fly aerobatics pretty much every time I strap my RV on and it does help for the occasional suare' into negative G flight. http://www.aircraftspruce.com/catalo...s/slimeftr.php

V/R
Smokey
Interesting history. I keep a pan under the tail of my Bucker in the hangar to catch the gunk. The Bucker always has a clean belly, well, except for the "clean" oil that manages to blow back there from my a bit leaky 2300 hour 0320. I would hate to see what the inside of the tube looks like running that far back. Thus far, no blockage. (crossing fingers)
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