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  #11  
Old 08-23-2013, 09:43 AM
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Mike S Mike S is offline
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Wink Proof of concept maybe??

Ross, it sounds like you are proving that all the work you put into the 10s cooling system is on the right track-------

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Rv-10, N210LM.

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  #12  
Old 08-23-2013, 09:59 AM
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Quote:
Originally Posted by rv6ejguy View Post
Yes, my ASI probe is tied into the main static vent and I checked my exit ASI against the one in the panel. At 110 KIAS, they are within a knot so I chose this speed for most of the testing. The pressure probes were tried both to the static source and cockpit.
For exit velocity you need a static port in the flow at the point you wish to measure. In the case of a coaxial pitot-static I'm reliably advised that the exact location of the pitot tip isn't a sensitive detail. The static location sets the point of measurement. Put another way, the tip of the pitot might be 1/2" forward of the static ports...no big deal.

Piccolo pressure is fine with delta to the aircraft static.

Quote:
My piccolo tube for the inlet was placed right at the rad face....
In the case of a diverging duct with a vertical exchanger that position would indeed result in the highest pressure indication. It's a little different with a horizontal exchanger (the air cooled cylinder set). See CR3405; pressure generally drops a bit as you move rearward from the inlet.

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It is just a testbed for ideas and has always been so for me. It wears the patches to prove it- with many failed experiments over the years but I have learned a lot from the failures as well as the successes.
Please accept my compliments for it.

THE MAN IN THE ARENA - Theodore Roosevelt
Excerpt from the speech "Citizenship In A Republic" delivered at the Sorbonne, in Paris, France on 23 April, 1910

It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat.
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Last edited by DanH : 08-23-2013 at 10:01 AM.
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  #13  
Old 08-23-2013, 10:16 AM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by Mike S View Post
Ross, it sounds like you are proving that all the work you put into the 10s cooling system is on the right track-------

The RV10 scoop was built many years ago as at that point I'd already seen the light that cowling mounted rads were a poor compromise. This scoop is not as optimally shaped as the RV6 one but I like to believe it will do the job. I also built a test rig to quantify HX thermal performance a few years back and there were some rather larger variations in temp vs. pressure drop. The Rad in the RV10 is not as efficient thermally as the Rv6 one but has slightly lower pressure drop.

I had been scared ever since I built the RV10 one that the rad was too small for the hp but assurances from my friend Russell and now my flight testing seems to indicate this is no concern. (hopefully)

We also have a friend in Oz who has built many successful under wing rad installations and his face areas and rad volumes are way less than ours per unit hp. He may not recover the exit velocity we do, but they cool well in a hot climate. They are cooling a 400hp V8 with less total rad area than me and volume is only 1.63 X mine. I may have gone too big on mine but did not want to build a second duct if I was too small. Russell also said my inlet was still way too big but I had to have unlimited ground cooling, figuring I could close the exit and be almost as efficient in cruise.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #14  
Old 08-23-2013, 10:27 AM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by David-aviator View Post
With regard to radiator location with liquid cooling, there is a guy in Europe running a Subaru with heat exchangers in inboard wing leading edge. I have not heard from him for some time but he had reported excellent results. I believe it was in a Robin but my memory may not be recalling that correctly.
This may have been Hans in Holland with a Jodel? He had good cooling but the rad areas and volumes were huge for the hp. Easy to get good cooling, harder to do it with low drag which is what I am trying to learn about here. Actually there was NO modern data I could find anywhere and little historical data on real numbers. I wanted something actual to plug into the math rather than wild assumptions.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #15  
Old 08-23-2013, 10:35 AM
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Quote:
Originally Posted by DanH View Post
For exit velocity you need a static port in the flow at the point you wish to measure. In the case of a coaxial pitot-static I'm reliably advised that the exact location of the pitot tip isn't a sensitive detail. The static location sets the point of measurement. Put another way, the tip of the pitot might be 1/2" forward of the static ports...no big deal.

Piccolo pressure is fine with delta to the aircraft static.



In the case of a diverging duct with a vertical exchanger that position would indeed result in the highest pressure indication. It's a little different with a horizontal exchanger (the air cooled cylinder set). See CR3405; pressure generally drops a bit as you move rearward from the inlet.



Please accept my compliments for it.

THE MAN IN THE ARENA - Theodore Roosevelt
Excerpt from the speech "Citizenship In A Republic" delivered at the Sorbonne, in Paris, France on 23 April, 1910

It is not the critic who counts; not the man who points out how the strong man stumbles, or where the doer of deeds could have done them better. The credit belongs to the man who is actually in the arena, whose face is marred by dust and sweat and blood; who strives valiantly; who errs, who comes short again and again, because there is no effort without error and shortcoming; but who does actually strive to do the deeds; who knows great enthusiasms, the great devotions; who spends himself in a worthy cause; who at the best knows in the end the triumph of high achievement, and who at the worst, if he fails, at least fails while daring greatly, so that his place shall never be with those cold and timid souls who neither know victory nor defeat.
Good point on the static source for the exit pitot. I am going to move that today and I'll be able to switch sources in flight to see the difference.

Great quote from Teddy here and I salute you for your testing too- most interesting to have some real data with your attention to detail.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #16  
Old 08-27-2013, 07:15 PM
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rv6ejguy rv6ejguy is offline
 
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I did a bit more testing with the revised probe setup. It was cooler at altitude this time so rad exit temp was down to 52C. Despite this and the door in the neutral position, V recovery at the exit was 87% at 100 knots IAS and 70C coolant temp. I want to try correlate exit temp with V recovery at a fixed speed to reduce variables. The problem I have is to get the coolant temp up. I'll have to block off some of the inlet for the cabin HX which is doubling as a small extra rad in the summer, just dumping overboard. Either that or I need some dive brakes so I can work the engine harder...

A number of data points so far suggest this scoop works well at recovering momentum at the exit compared to even the throttled ducts others have tested and published the results for here on VAF a while back with air cooled engines. I'm seeing 59% with the exit door fully open and as high as 97% (old probe setup) with the door closed vs. 51% for a stock RV8 outlet and 64% for the throttled exit at similar TAS as my tests.

These are preliminary and my testing continues but from the data so far, there is nothing to support the old notion that air cooled engines will always have less cooling drag than an equally optimized liquid cooled setup.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #17  
Old 09-26-2013, 05:12 PM
SHIPCHIEF SHIPCHIEF is offline
 
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Ross;
How is the cooling drag reduction project using the 'Meredith effect' doing?
(Thanks for the help on turbochargers)
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  #18  
Old 09-26-2013, 09:49 PM
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rv6ejguy rv6ejguy is offline
 
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Quote:
Originally Posted by SHIPCHIEF View Post
Ross;
How is the cooling drag reduction project using the 'Meredith effect' doing?
(Thanks for the help on turbochargers)
I've been fighting a vexing intermittent comm problem for months now. I believe (dearly hope) I have finally isolated it down to a bad intercom channel. For the time being, I've crossed rigged the pilot PTT and headset jacks to pass through the copilot channel and wiring. A few more hops and I'll know if this is really the cause, then I can get outside the pattern and gather the rest of the numbers.

Everything except the radios have been performing perfectly. My new door actuation system works wizard and cooling is amazing even with the door closed.
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Ross Farnham, Calgary, Alberta
Turbo Subaru EJ22, Marcotte M-300, IVO, RV6A C-GVZX flying from CYBW since 2003- 424.4 hrs. on the Hobbs,
RV10 95% built- Sold 2016
http://www.sdsefi.com/aircraft.html
http://sdsefi.com/cpi.htm


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  #19  
Old 01-13-2014, 07:10 AM
cujet cujet is offline
 
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Nice setup!

I had always been under the impression that a properly configured, fan forced cooling system resulted in markedly less drag. And the possibility of thrust. I have to wonder if the HP required to drive such a system would be put to good use.
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  #20  
Old 01-13-2014, 09:01 AM
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Quote:
Originally Posted by cujet View Post
Nice setup!

I had always been under the impression that a properly configured, fan forced cooling system resulted in markedly less drag. And the possibility of thrust. I have to wonder if the HP required to drive such a system would be put to good use.
I have a fan on the back side of my radiator, but I have my VP-200 shut it off during cruise - I guess I could turn it on & off manually and get a few data points....

John
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