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  #1  
Old 06-11-2018, 06:38 AM
rjcthree's Avatar
rjcthree rjcthree is offline
 
Join Date: Jan 2007
Location: Bay Village, OH
Posts: 736
Default Remote oil cooler inlet screen

I'm having oil temperature issues with the rising ambients in NE Ohio. Last year I managed it as I was just starting phase 1 on a new OH engine, but as I step almost out of phase 1, I'm still running a little higher than comfortable. Maybe it's broken in, maybe not, but there's room for improvement regardless.

Setup: 9A, 320 H2AD, AC 9 row 800074 fed from screened-inlet 3" SCAT from above/behind #4. AS 15W50. Low oil consumption. Good transition from SCAT to cooler face. Maybe a little restricted on cooler outlet via semi-open ductwork to center exit, to be relooked at. 75% power, 8000ft DA, just ROP, 68F OAT, 215F oil temp. Stock cowl outlet. CHT in 350F-360F range. Temp sensor is in range. I can see the vernatherm closing in the data (everything else steady state, the OT data has one rate of change below 175F, it pauses at ~175F for 30 sec or so, then resumes upward at a lower rate of change, distinct and repeatable in the data).

The single question I have at the moment is regarding screening the inlet to the SCAT/cooler. At this moment, the 3" inlet has a glorified window screen across it. Has anyone quantified the air pressure differential to the cooler with and without the screen?

When running baffle mounted coolers, I usually don't see screens. I will also be looking at a rolled edge to the SCAT, right now it's just squared off. Removing the screen is a easy task.

Thanks.
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Rick 90432
RV-9A tip-up, O320H2, Ellison, Dynon D180
First Flight 2017apr23 - Out of phase 1 2018jul07
RV-8 tail kit received with a 5 year plan
2011-2018 VAF contributor
Dog is my copilot, rest in peace 2015APR28. I miss that dog.

Last edited by rjcthree : 06-11-2018 at 06:42 AM.
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  #2  
Old 06-11-2018, 06:52 AM
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DanH DanH is offline
 
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Location: 08A
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Default

Quote:
Originally Posted by rjcthree View Post
The single question I have at the moment is regarding screening the inlet to the SCAT/cooler. At this moment, the 3" inlet has a glorified window screen across it. Has anyone quantified the air pressure differential to the cooler with and without the screen?
Not quantified as pressure loss, but the screen is a large area reduction...like 50%.

Remove screen, fly, report.
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  #3  
Old 06-11-2018, 07:19 AM
pilotkms pilotkms is offline
 
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Location: WARNER ROBINS, GA
Posts: 212
Default 4 SCAT ?

I have similar setup but with IO360 and 4”, with screen. Oil temps 177 - 192 and Cruise CHTs running 390. Have seen cooling issues here on VAF like yours due to 3” SCAT.
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  #4  
Old 06-11-2018, 08:46 AM
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airguy airguy is offline
 
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Location: Garden City, Tx
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Default

I started with a screened inlet as well - removed it on 3rd flight of Phase I due to very high oil temps, that single change made quite a bit of difference.

Just pull the diffuser off the front face of the oil cooler during annual to check for bugs/debris and call it good.
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Greg Niehues - VAF 2018 dues paid
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N16GN flying! http://websites.expercraft.com/airguy/
Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
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  #5  
Old 06-11-2018, 10:36 AM
rocketman1988 rocketman1988 is offline
 
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Location: Sunman, IN
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Default Screen

For anyone interested, check this out:

https://www.mcmaster.com/#woven-wire-cloth/=1d8m4qx

Data is posted on wire size, number of openings, and open area.

It is amazing how much area those little wires take up!
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Aerospace Engineer '88

RV-10
Structure - 90% Done
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On Gear
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  #6  
Old 06-11-2018, 12:15 PM
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rjcthree rjcthree is offline
 
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Location: Bay Village, OH
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Default Delta

Greg, do remember about how much difference? I realize things were probably changing fast in those hours.

Dan, that's the plan. I have to pull the top cowl to do it, I may check VT seating then too. I checked the old VT (first run) and it has a reasonably complete circular seat marking, open in about 30deg of the circumferance. I replaced it at OH with new.

I'm also interested in looking at creating an RV-8 style flow management 'nose' to cover the A-model tube intersection, just to get the hot cooling air out a little more efficiently before I think about cutting the edge of the cowl away, or going to the SW 10599R or whatever other nonsense I get into on this little tweak.

It's a carbed 320 limited to 2600 RPM due to sensenich fixed - this should be relatively easy to resolve.
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RV-9A tip-up, O320H2, Ellison, Dynon D180
First Flight 2017apr23 - Out of phase 1 2018jul07
RV-8 tail kit received with a 5 year plan
2011-2018 VAF contributor
Dog is my copilot, rest in peace 2015APR28. I miss that dog.
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  #7  
Old 06-11-2018, 01:48 PM
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airguy airguy is offline
 
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Quote:
Originally Posted by rjcthree View Post
Greg, do remember about how much difference? I realize things were probably changing fast in those hours.
There were a lot of things changing quickly during those first few hours, yes - but I do remember that both of my first 2 flights were cut to between 15 and 20 minutes due to oil temps in the 230's and approaching 240. After removing the screen I was able to fly 45 minutes with oil temps staying in the 220's. This was with an IO360 running full-bore with 3" scat to a firewall-mounted 7-row cooler, which turned out to be completely inadequate due to piston oil squirters. I later upgraded to 4" scat, a 10-row cooler, and a good diffuser for the inlet air to the cooler and now I only see 215-220 during an extended hard climb and 195-200 in cruise.
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Greg Niehues - VAF 2018 dues paid
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N16GN flying! http://websites.expercraft.com/airguy/
Built an off-plan 9A with too much fuel and too much HP. Should drop dead any minute now.
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  #8  
Old 06-16-2018, 12:08 PM
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rjcthree rjcthree is offline
 
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Location: Bay Village, OH
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Default First data form screen removal - directionally correct

I removed the screen. Conditions aren't exact, and flight time was limited due to WX.

With screen over the baffle inlet to the 3" SCAT: OAT 63F, 20.0"MP, 125 IAS, oil temp 208F. Ave CHT 356F.

Without screen over the baffle inlet to the 3" SCAT: OAT 71F, 21.0"MP, 125 IAS, oil temp 196F. Ave CHT 350F.

More testing to be done, but removing the screen was an improvement. I will get more data over the next week to solidify the impact and decide next steps, if any.

I don't see evidence of blowby in the oil - with ~25hrs on the oil, it's still a light amber - darker than EV olive oil but lighter than Jim Beam in color

7/1/18 UPDATE : this data is probably garbage, not enough time in flight or steady state conditions for the data to be solid.
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Rick 90432
RV-9A tip-up, O320H2, Ellison, Dynon D180
First Flight 2017apr23 - Out of phase 1 2018jul07
RV-8 tail kit received with a 5 year plan
2011-2018 VAF contributor
Dog is my copilot, rest in peace 2015APR28. I miss that dog.

Last edited by rjcthree : 07-01-2018 at 05:43 PM. Reason: More careful look at the data
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  #9  
Old 06-19-2018, 09:50 AM
rjcthree's Avatar
rjcthree rjcthree is offline
 
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Location: Bay Village, OH
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Default Oil temperature vs ambient temperature

Other posts have stated/suggested that once thermal saturation occurs in the oil cooler, all other things being equal, oil temperature will go up (down) with rising (falling) ambient (OAT) air temperatures, aproximately degree for degree. Is that a solid description within the temp ranges we're talking about?

If it is, I'm still in the penalty box. I wanted 30F decrease, need at least 20F, and got 10F-15F by removing the screen from the 3" SCAT. Example: 73F ambient, 21" MP, now running 206F OT, CHT fell another couple of degrees average (so it's working, just not enough). I'm ok having to block some of cooler flow for winter.

Plan B: 4" SCEET to feed a new diffuser box, sticking with the 9-row 800074 cooler at the moment. Trying not to make too many changes at once.
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Rick 90432
RV-9A tip-up, O320H2, Ellison, Dynon D180
First Flight 2017apr23 - Out of phase 1 2018jul07
RV-8 tail kit received with a 5 year plan
2011-2018 VAF contributor
Dog is my copilot, rest in peace 2015APR28. I miss that dog.
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  #10  
Old 06-19-2018, 09:56 AM
TS Flightlines TS Flightlines is offline
 
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Default

Rick---one change at a time and test under similar conditions. Too many, or different conditions and yo wont know what fixed it, or made it worse, or did nothing. 2 many changes can counteract each other.

Tom
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