VW cooling

cardiffrob · Post by **cardiffrob** » Wed Apr 09, 2008 2:08 pm

For oil cooling, cheapest/lightest option is to duct air over the fins on the sump of the crankcase.

http://s82.photobucket.com/albums/j279/ ... 000542.jpg

Rounded edges on the intake to the sump fins (with oil cooler fitted at the back of the duct), ally sheet folded to duck air through the fins and to protect the front fins from shock cooling in descent plus a spinner that 'spins' air outwards to the barrels.
I'll bend and curve the leading edges of the scoops when I find out how much less intake area I can get away with. Lowering the leading edge will reduce drag but also slow the airflow just aft of the intake edge as it spreads out into the 'plenum' chamber. This will help to even out the flow.

Baffle material is GRP weave that has been smothered in red fire-stop (250 degrees C?) silicone sealant and placed onto a waxed and polished piece of glass (greenhouse door) before being squashed down a bit.

cardiffrob · Post by **cardiffrob** » Wed Apr 09, 2008 2:27 pm

http://users.lmi.net/~ryoung/Sonerai/Engines.html

http://home.hiwaay.net/~langford/faq/ch ... cool2.html

http://www.ch601.org/resources/cooling_systems2.htm

http://www.ch601.org/resources/cooling_systems1.htm

Some useful links and other info.

cardiffrob · Post by **cardiffrob** » Wed Apr 09, 2008 2:41 pm

http://s82.photobucket.com/albums/j279/ ... ezones.gif

....."Everybody has at one time or another come across this cowling shape (Fig. 22). Notice the split between the pressure and lift on the spinner! This is one reason why you should have a good spinner bulkhead in front of the propeller. The forces on a large spinner can be substantial. Notice the lift on the front part of the cowling which is trying to suck the front end open. This is a good place for some exhaust louvers or openings for venting hot air out of the engine compartment. Further back on the cowling and in front of the windshield we have high pressure air. A good place to install an air intake. That is exactly where most cars have the fresh air pickup. It is also the place where Porsche and other sports cars pick up the cooling air for the turbo intercooler. ".....

This one is good. Lots of high pressure under the nose which is good for ducting air past the sump and a step at the bottom of the sump creates a low pressure zone to suck fumes out of the cowling. I used a similar system to draw hot air from under the heads.

Rob Swain · Post by **Rob Swain** » Tue Apr 15, 2008 6:11 am

I finally found the Great Plains link I was looking for.

http://greatplainsas.com/iscooltin.html

There used to be a baffling manual (as in to make engine baffles, not just plain confusing) on the site somewhere too!

eyesoar · Post by **eyesoar** » Tue Apr 15, 2008 7:09 pm

I did chuckle Rob!
Now surely, to have a complete suite of documentation, every aircraft should have a Flight Manual, a Maintenance Manual and a Baffling Manual!
Any more like that?
Roger

cardiffrob · Post by **cardiffrob** » Tue Apr 15, 2008 9:56 pm

I have the GPASC Baffling manual. Only good if you are building a pressure-type full cowl rather than a lightweight one like we tend to need over here.

Mike Mold · Post by **Mike Mold** » Wed Apr 16, 2008 10:08 am

I got the cooltins for my D9's VW from German & Swedish (now GSF). Stockists are listed at http://www.gsfcarparts.com/contact/branches.asp.

Phil Burgess · Post by **Phil Burgess** » Wed Apr 16, 2008 5:00 pm

I got the GPASC baffling manual too... I'm still baffled!

cardiffrob · Post by **cardiffrob** » Fri May 02, 2008 1:27 pm

http://s82.photobucket.com/albums/j279/ ... =cowl3.jpg
http://s82.photobucket.com/albums/j279/ ... =cowl2.jpg
http://s82.photobucket.com/albums/j279/ ... =cowl1.jpg

...are 3 shots of my version of the VW cowl.
The sump cooling duct allows cold air in the high pressure area at the front of the cowl (and just below the spinner) to flow air past the sump gills and then through the oil cooler which is at the back wall of the duct. This then dumps overboard below the rear edge of the bottom cowl.
One shot also shows the baffling on the front of the pots that stops (?) shock cooling of the front pots.

Hope this helps.

cardiffrob · Post by **cardiffrob** » Sun May 04, 2008 10:52 pm

http://s82.photobucket.com/albums/j279/ ... =cowl4.jpg
http://s82.photobucket.com/albums/j279/ ... =cowl5.jpg

Taken today. The ducting takes air from the high pressure area and draws it past the gilled sump before running it past the oil cooler. The area is shielded from the exhaust heat by an alloy sheet that has a heat-reflective asbestos-type covering bonded on.
The red baffle material is grp weaved matting that has had red 250 degree celsius RTV squeezed onto it and rollered flat to make a heatresistant and chafe-proof edging to seal against the cowling lip.

http://s82.photobucket.com/albums/j279/ ... =cowl6.jpg
....shows the attempt to take hot baffle air and duct it round the inlet manifold to keep down carb icing. I doubt that it has much (any?) worthwhile effect so it may yet be removed. The oil heated inlet sounds a better system but weighs a lot more.

Phil Burgess · Post by **Phil Burgess** » Mon May 05, 2008 9:46 am

I had one of those oil heated inlets on my last mono. It wasn't connected to the oil supply though and when running with the cowl off the outside of the manifold just down stream of the carb would get a 1/4" build up of hoar frost on it! With the cowl on think there was enough warm air circulating inside the cowl to prevent this and I never experienced carb icing in flight (as far as I know). My new project will be set up the same way but not connected to the oil circuit.

I was under the impression that carb icing is only a problem if it forms in the venturi or on the butterfly valve it's self? So what effect does heating the manifold down stream of the carb really have on reducing icing? I bet it just reduces performance...

Brian Hope · Post by **Brian Hope** » Mon May 05, 2008 10:41 am

Phill, the idea is that the heated manifold also puts heat into the venturi area by heating the body of the carb as well. I do not believe that it has any negative effect on performance, as the air entering the carb is unheated. Putting pre-heated air into the carb is what reduces performance.

cardiffrob · Post by **cardiffrob** » Mon May 05, 2008 11:20 am

Anyone know how heavy they are? Has anyone got one for sale?
Ta.

Phil Burgess · Post by **Phil Burgess** » Mon May 05, 2008 8:56 pm

I'll weigh mine tomorow but it's not for sale.

cardiffrob · Post by **cardiffrob** » Tue May 06, 2008 9:15 am

Would it be hard to make one? Is it brazed, cast or welded?