Reminds me of that song.   Suddenly I'm feeling so vain : )

 

You probably think this emails about you—don’t you – don’t you

 

HAHAHAH

 

From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net]
Sent: Monday, August 21, 2017 8:01 AM
To: Rotary motors in aircraft
Subject: [FlyRotary] Eclipse viewing?

 

Anyone else planing to see from the air?

 

I made last minute plans to see total eclipse yesterday when I heard that a 90 %  eclipse is like sex without a happy ending.  

 

The totality band is about 300 miles north of me (at my off grid CO shack) so me & M plan to rendezvous with totality near Casper, WY.   No landing, will watch from air then return to Salida,CO.  I hear that it might be possible to see the approaching/receding  moon shadow at start and end of totality.

 

Reminds me of that song.   Suddenly I'm feeling so vain : )

Sent from my iPad

On Aug 21, 2017, at 06:46, Tracy <flyrotary@lancaironline.net> wrote:

Hi Will,   

My rule of thumb for rad core volume is between 2 and 3 CI per HP.  At 375 CI you would be on the small side but I think your calculation of CI is off.  Thick rads can be efficient but will need more CI. 

 

The needed CI  is of course affected by core design, duct efficiency, aircraft speed, etc.  At 4.5" thick you should be in at least a 200 mph top speed design, otherwise you might not have enough diffuser pressure to force the air through.

 

Other thoughts:  Airflow around the engine is a waste.  Very little cooling for a lot of drag.  There is no such thing as drag being a good idea unless you are landing (flaps) or flying a Stuka dive bomber.  A little Cooling Airflow around coils, alternators, electronics, etc. is a good idea.  

 

Personally I've had good luck with the RX-7 oil cooler.    There is a big mismatch between the delta P air pressure required between that cooler and your rad though.  Separate ducts would be a good idea otherwise the oil cooler might hog most of the airflow.   Even the pressure on the back side of the heat exchangers can affect the balance but it sounds like you are going for separate outlets so may not be a factor here.

 

Let us know how the project goes!

 

Tracy Crook

   

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On Aug 20, 2017, at 19:42, william Aldridge <flyrotary@lancaironline.net> wrote:

Ok I've spent the last few years on Paul Lamars list and got tired of it. I'm designing and building my own design and was wondering what you guys say is the right size for the water and oil coolers?  I plan on p-porting the engine so am expecting 200+ hp. I know there's a lot of factors that go into rad sizing but let's just say i get a moderately efficient cooling system, how much volume do i need?   I've got a cross counter flow setup drawn in now that is about 375 cu inches and 10.5 x 17.75 on the face and about 4.5 inches deep.   The water cooler will be mounted perpendicular to the airstream with an adjustable exit ramp.  For the oil cooler I’m planning on using a standard rx 7 oil cooler that will use a wedge diffuser on the intake and exhaust out shark gills on the side of the cowling. I will also have quite a bit of airflow around the engine itself.  That will probably take the airspeed down somewhat but it’s such a slick small airframe that I think it could get uncomfortably close to Vne in level flight, so a little unnecessary drag might be a good thing.

 

Thanks, 

 

Will Aldridge 

 

 

Sent from Mail for Windows 10

 

From: Todd Bartrim
Sent: Sunday, August 20, 2017 4:56 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Coolers

 

Another great example of how tech changes our lives. Back when, we had to guess at what was happening under the cowl. Now a few clicks on Amazon and 2 days later we can have all the investigative tools we need to know instead of guessing.

 

Virus-free. www.avast.com

Todd Bartrim

 

On Sun, Aug 20, 2017 at 2:45 PM, Ernest Christley <flyrotary@lancaironline.net> wrote:

Just a point to highlight what Todd was saying about exit ducting.

 

On the Dyke Delta I built, I had a water cooler under the cowl.  The other water cooler and oil cooler were buried in the strakes.  The air exited the cooler under the cowl close to the firewall, and was supposed to go down and out the bottom.  It didn't do that.

 

What it did was set up a horizontal whirlwind inside the cowl.  The air hit the firewall and then spun around clockwise.  I discovered what was happening during the investigation of why some hoses were melting.  I constructed a crude dam to force the air out the cowl exit, and saw a significant drop in temps.

 

All that is to say that the airflow INSIDE the cowl is as important as the flow outside. Today, I would tuft the engine with pieces of yarn on hoses, wires, and engine mount tubes.  I have a tiny camera with a 15ft cord that turns my phone into a video surveillance monitor.  I'd stick it in various places under the cowl and see how the air flows with the engine running.

 

 

On Sunday, August 20, 2017 4:22 PM, Todd Bartrim <flyrotary@lancaironline.net> wrote:

 

I didn't crunch any numbers in my decision to use this Laminova heat exchanger, I only knew that in climb and level flight I had different cooling between oil & water and figured I could balance it out with this heat exchanger at a small price in weight. It certainly doesn't increase the cooling of the system as a whole.

 It should be pointed out that these are not coolers, only heat exchangers. So if a oil/water cooling system doesn't have adequate cooling to begin with, then this will do nothing to address that.

In my case I found that I could climb from 2000' ASL (field) to 10000' ASL in 3 minutes before my coolant temps hit redline, but I still had plenty of room on my oil temps. In level flight my coolant temps would drop but my oil temps would slowly increase to redline. So I figured this would help me borrow from Peter to pay Paul. It still didn't address cooling shortfalls properly.

  I believe the biggest culprit in this was the shape and position of my oil cooler inlet which was form over function (hey, it looked good).

   Now I have made a lot of other changes which hopefully should address improper cooling airflow. As well as reshaping the oil cooler inlet duct I also did outlet ducting for the oil cooler, intercooler and right coolant radiator. I did not build a outlet duct from the left radiator due to it's close proximity to the turbo exhaust pipe. This interfered with the space required for a proper exit duct and I figured it probably would be a good idea to have some airflow over the turbo. Previously I had only ducted my inlets and left the air to find it's own way out of the cowl through what I believed were adequate sized exits. Ed Anderson spent a lot of time researching cooling air flows and finally was able to beat it into me that exit ducting is every bit as important as inlet ducting.

  The other change I made which I hope will have a significant effect is I bought a new set of deep pitch blades for my IVO prop. I also cut it down from 76" to 70". This should give me a higher cruise speed with the accompanying increase in cooling airflow with the same RPM.

So with all these changes it's unknown if this Laminova cooler will have any benefit but I'm certainly not going to remove it as it it's only cost at this point is a few pounds which if I need to get rid of that I'll just start jogging again... not a bad idea anyways :-)

 

On Sun, Aug 20, 2017, 09:46 Thomas Mann, <flyrotary@lancaironline.net> wrote:

As a side note to these observations there is something to be said about overcooling the engine oil. (i.e. cooling the oil too much at higher altitudes or in cold conditions.)

An oil-to-coolant system help to moderate that scenario.

 

T Mann

 

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