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Fresh Air Source From Engine Compartment??

L

laserman

Active Member
RV8 - OK.. So Vans has the air source to the heat muffle for cabin heat coming from the left corner of the upper engine compartment..

Can.. more importantly.. should I ?

Use the same compartment source for the not-heated air venting source? It would make the installation simpler, and I expect lower pressure drop in the scat tubing having a much shorter ducting run? than grabbing it from the CB-1002A or CB-710A forward air ramps.

I assume given the volume of air entering the chamber that heating of the incoming air is minimal as well as picked up engine odors.

Yes it eliminates the option of an air source during a fire, but most fire related procedures include closing all venting.. and yes I understand a slightly increased risk of CO2 issue. (and maybe that reason enough not to do it)

But I assume CO2 issues is more of an issue with air flow in the lower engine compartment. Have uses dual SS heater control boxes. One for heated, one for non-heated, cross connected via interior via ducting pic shown.

A pic is attached of what I was thinking..

Plus a photo of interior dual venting connections?

Just need a push to take one direction or another?

My guess its all about balancing risks?

Thanks... Alan

FRESH AIR SOURSE OPTION ??

Fresh Air by Arthur Karpinski, on Flickr

INTERIOR CROSSCONNECTED DUCTING

Cross Ducting by Arthur Karpinski, on Flickr
 
Air source from just about anywhere that assures you can't get Co2 is acceptable.

The interconnect between cold and hot using the Y's is not going to work very well. Very little air will make the 120 deg turn towards the other vent unless you form some type of a splitter to insert within the Y.
 
rvbuilder2002 said:
Air source from just about anywhere that assures you can't get Co2 is acceptable.

The interconnect between cold and hot using the Y's is not going to work very well. Very little air will make the 120 deg turn towards the other vent unless you form some type of a splitter to insert within the Y.
Click to expand...

I think you mean CO. (Carbon Monoxide)
 
Thanks for the feedback.. Yes the engineer in me should have caught the CO/CO2 error...

Understand about the Y fitting may be a poor performer..

Its super easy to make both vent sources.. heated / non-heated supplies, depending on season... (Central NY here home base:B16)

Project started in 2004 with an EGG H6 Sube engine.. Tore off the engine and panel installation and started over this fall with IO/360

I do it right.. Because I do it twice...:eek:



Pics of First time build with Sube Engine and Steam Gauges...

Was so young.. and dumb...

Karpinski Sub H6 2004 by Arthur Karpinski, on Flickr

DSC01010 by Arthur Karpinski, on Flickr

DSC01051 by Arthur Karpinski, on Flickr

DSC01050 by Arthur Karpinski, on Flickr

Karpimski IO360 2016 by Arthur Karpinski, on Flickr
 
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My 182 pulls fresh air off the rear baffle like you show.

Contrary to rvbuilder2002, I think your wyes will work fine. I wyed an eyeball vent off the scat line to my defroster and pressure seems to equalize between the defroster and the eyeball.
 
Lots of available flow please...

Yes.. We shall see with the Y fittings... Have three of the Vans black "throttle-able"eyeball fitting ...Two down low..and one for defrost... (Defrost scat run not plumbed in yet) Need lots heat in the winter... and cool air in the summer ;)
 
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Y fittings..

Fully agree... Y fittings are flared for (easy) installation in that way.. Not optimal for sure... The big first questioning was drawing air from the upper cowl OK ? .. Which seems to be ok to do...

Lots more and important things ahead on this project... (Again)

Thanks all for the feedback

I do it right.. Because I do it twice...
 
Check out the Cirrus SR22 G3.
In this generation, they moved the intake from the wings (G2) to a NACA duct on the right side cowl.
Also note how they treat their emergency procedure for cabin smoke or engine fire.
Seems like a good way to get fresh air.

They have a heat mixer to provide warm/cold/mixed air to both the front and back vents.

I would do it this way on my -10 but I can't figure a route over the spar to get to the back seats (other than through an overhead or through the center tunnel, both not ideal)
 
Cooling issue...not you, the engine

I went with NACA scoops on the side of the fuselage for two reasons. The first is that they provide a huge amount of air. You will even get flow from the prop at idle on the ground. No CO problem as the air is truly fresh.

My concern with your setup is that you are robbing cooling air from the engine when you most need it, summer. Both you and the engine need cool air. If you don't get it, you get sweaty. If the engine doesn't get it, you get sweaty replacing cylinders. You might be able to get away with this in winter but you won't need the cold air in the cockpit then. Food for thought.
 
rvbuilder2002 said:
:eek: You're right Mel, I had just finished reading the OP's post, (who had also written Co2) and had that stuck in my mind.

Why didn't he get scolded?;)
Click to expand...

Because I missed HIS entry error. Guess I just pay more attention to your posts. Sorry.
 
I'll take my fresh air from NACA ducts.

There is a temperature rise between the cowl inlets and a baffle wall duct. Some of it is ram rise (there's another thread on that subject right now, as it relates to OAT probes), and some of it is heating from the upper cylinder fins.

I've measured the temperature increase repeatedly, comparing OAT to a temperature probe inserted in the plenum feeding a remote oil cooler from the rear baffle wall...essentially the same thing as feeding the cabin. Two examples from my notes, morning and afternoon business trip, out and back:

Hot day testing (107F on the ground at Jackson MS)

Morning OAT 64F @ 8500 ft
Oil cooler inlet probe 81F
81-64= 17 degree rise

Afternoon OAT 86F @ 2500 ft
Oil cooler inlet probe 101F
101-86= 16 degree rise
 
YES !! Going to take the NACA scoop direction.. Mount the scoop on the lower cowl.. Brain did not connect with that option… There is plenty of room to easily connect / disconnect the scat from the scoop when the lower cowl needs removal… Really don’t see any down side. No CO issues.. Sounds like top notch flow when desired… Courtesy photos of installation to follow in a few days.. Many thanks… Al
 
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