Cabin ventilation.
 

Hello,

In addition to the standard ventilation air ducts I'll be also adding an Aerosport overhead console with four additional vents, piped in thru NACA ducts on either side of the tailcone. My question is this: with all this air blowing into the cabin do I need to make provisions for discharge air? Where does all this air go?

Thanks,
Dave

Jack it will escape thru your baggage bulkhead sides. It goes back into the tail cone and other little places.

Geoff

Do you mean thru the corrigated gaps on the rear bulkhead covers? We were told (can't remember by who) to fill those in with foam insulation to prevent drafts in the winter.

You have to work really hard to make the cabin air tight. I've be in about a half dozen different RV-10s that have overhead consoles. None have done anything special to accomodate releasing the air pressure.

I would recommend Aerosport's NACA controller. It helps to reduce the volume of air when needed. The NACAs are quite efficient at bring air into the cabin. To the point that even with some vendor's vents closed, air still gets in. The controller assists in managing that issue.

That outgoing cabin air has two ways to leave. It'll either escape through various gaps and holes, creating drag, or you'll install a cabin-air exit in a relatively low-pressure area on the fuselage.

I've asked about cabin air exits on VAF a couple times with zero response.

As far as I know, the only general aviation production plane with them is the Beechcraft Bonanza. It's located about halfway back from the wing, on the tailcone.

Dave

The piper archer has a large screen covered exit on the belly under the rear seats. With that said, I have the same set up you are planning and have no issues with the air escaping through the baggage bulkhead. I have insulation on the bulkhead, but it doesn't block the corregations

sealed tight
 

Early in the build I went to great efforts to try to eliminate air drafts n the cockpit. The approach that I took was somewhat different than most of the hangar talk that I had been hearing. Instead of trying to block the air from infiltering the cabin from the tail cone (nearly impossible) we spent time sealing the areas that the air tries to escape the cocpit. These areas are possibly, (but not proven) firewall penetrations, any wing root openings there is low pressure here, aleron control penetrations, door seal, etc. By doing this you can shut the fresh air inlets and feel no draft in flight...none. Also noticable is, I really don't think I get as muvh air volume in the naca vents as other -10's that I have flown but that's what the air conditioning is for.

The main reason for this was not so much for draft prevention however that was an added benefit, but for drag reduction. Any air that "leaks" in has to "leak" out and causes drag in the process.

A little off topic
 

Sorry to be a little tangential but I've been wondering if a NACA vent on each side of the fuse is necessary. Will a vent on only one side do the job?

I generally have all my vents shut once at altitude, quite often heat on in the middle of the summer. Why more vents? If it gets to hot in the cockpit, I just go higher.:D When you descend into 100 F plus air, you often want to keep the vents shut, its like turning on the furnace when you don't want it.

Well, the electric butterfly valve we got with the vent kit has two ports, and every photo I've seen of its installation shows NACA ducts on both sides. Guess I never thought of putting in just one. Oh well, if a little is good and more is better, too much must be just right.