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Cabin ventilation.

JackinMichigan

JackinMichigan

Well Known Member
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.
 
jwilbur said:
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?
Click to expand...

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.
 
I might be wrong (I’m not flying yet so this hypothetical), but I’m of the opinion that one NACA scoop is sufficient to provide air to the entire overhead console and it’s potentially how you distribute the air which can drive the one vs two scoop decision. In my case I built a manifold/ducts into my console that delivers air to each of my 4 eyeball vents as I did not want to pressurize the entire console. I also went with only one scoop and no valve/controller. We’ll see how this works in reality.
 
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Auburntsts said:
I might be wrong (I?m not flying yet so this hypothetical), but I?m of the opinion that one NACA scoop is sufficient to provide air to the entire overhead console and it?s potentially how you distribute the air which can drive the one vs two scoop decision. In my case I built a ?manifold? into my console that delivers air to each of my 4 eyeball vents as I did not want to pressurize the entire console. I also went with only one scoop and no valve/controller. We?ll see how this works in reality.
Click to expand...

I like the sound of this. I wonder if anyone else who's flying has done it this way and can give a report.
 
I have been flying since winter, and I can tell you that I am glad I put in 2 NACA inlets. I do not have the controller and just pressurize the OH console. This winter I could feel a slight amount of air leaking around the rocker switches mounted in the OH. Not enough leaks to be an issue. I did use the Steinair eyeballs, which don't let anything pass through when closed. If I did it over, I wou ld not change a thing. IMHO you can never have enough fresh air for passengers!
 
I built ducts into the accuracy console on my last one. No stray airflow. Console is also removable. I made the ducts from cardboard and glass/resin. Molt Taylor style.
 
I have 400 hours now with dual NACA vents that pressurize the overhead console. It works very good and you do get some airflow when taxiing. One
NACA will work but 2 is better if you want more airflow especially at lower air speeds in the patterns or taxiing. As for the controller valve I flew for 3 months
without it. I felt it was not needed at the time. Then one day flying in the winter here in Ohio I felt the cabin was quite cold and I noticed the overhead was very cold too touch. After that I installed the controller and now in the winter you can shut the entire overhead off and the cabin is much warmer. Also it is nice to adjust the valve so you can open all the vents wider and get a bigger smoother airflow stream and adjust with the controller.
Also try shutting down the rear vents sometime when someone left them wide open in the rear seat area. With the controller it is very easy. Just my observation after 400 hrs. I would do it the same if building another 10.
FWIW

Geoff
 
Aerosport1 said:
Also try shutting down the rear vents sometime when someone left them wide open in the rear seat area.
Click to expand...

Excellent point. Not enough, by itself, to sway me on the purchase of the controller (of course I reserve the right to reverse myself once I'm flying :D), but it's enough to make me add checking the status of the rear vents to my preflight checklist.
 
Todd not trying to sell you anything or a control valve just trying to give you some good information from someone who has been flying the RV-10 for 400 hrs
and my observations and experiences.

Geoff
 
Aerosport1 said:
Todd not trying to sell you anything or a control valve just trying to give you some good information from someone who has been flying the RV-10 for 400 hrs
and my observations and experiences.

Geoff
Click to expand...

Oh I know -- you're a good egg and make some really good products and provide outstanding support. :) I'm really just pointing out there's more than one solution to the problem. And like I said, I may end up with a controller and 2 scoops before it's all said and done, but I'm going to try a minimalist approach first. If I find it lacking, I can easily add another scoop and/or a controller to my present setup.
 
Just wondering

Auburntsts said:
I might be wrong (I?m not flying yet so this hypothetical), but I?m of the opinion that one NACA scoop is sufficient to provide air to the entire overhead console and it?s potentially how you distribute the air which can drive the one vs two scoop decision. In my case I built a manifold/ducts into my console that delivers air to each of my 4 eyeball vents as I did not want to pressurize the entire console. I also went with only one scoop and no valve/controller. We?ll see how this works in reality.
Click to expand...

how this ended up for you, Todd. Did you install one NACA duct or two? Did you get a controller from Geoff? Are you happy with your setup or would you change anything?
 
Bill Boyd said:
how this ended up for you, Todd. Did you install one NACA duct or two? Did you get a controller from Geoff? Are you happy with your setup or would you change anything?
Click to expand...

I ended up with just the one NACA scoop and no controller. In flight the one scoop provides plenty of air and the eyeball vents control the flow without problems -- on the ground the flow is pretty anemic but for me it's not a big deal. I'm happy and wouldn't change my setup.
 
Actually, Geoff's controller is more beneficial in the winter. Without it, the overhead console is pressurized and every switch, valve, light, etc will leak air. With the controller, it greatly reduces the air pressure when closed. This makes for a much warmer cabin in the winter.
 
Non-issue.....

rleffler said:
Actually, Geoff's controller is more beneficial in the winter. Without it, the overhead console is pressurized and every switch, valve, light, etc will leak air. With the controller, it greatly reduces the air pressure when closed. This makes for a much warmer cabin in the winter.
Click to expand...

My air is ducted to the eyeball vents and not just dumped into the entire overhead console so I don't have air leaking out of every gap/seam/hole. This is where having quality vents, like the ones from Stein, pays off.
 
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Cabin Ventilation

I've only put one Naca Vent in to feed the four vents in home grown overhead console. More than enough airflow even when taxiing on the ground. Mine is the standard Vans Naca positioned just behind and just above the baggage door. Made the decision to put only one in, and only on the Port Side after discussion with Lancair owner who had put one Naca Vent on the Starboard Side which was completely useless, with virtually no airflow to his overhead. Got to have a lot do do with the Prop Wash Airflow spiralling around the plane, makes you think that the extra Vent some folk put in are only for decoration and not providing any useful function. Cheers from Western Australia
 
NACA vent

I also put in only one vent and experience plenty of airflow to the overhead console. I put mine on the starboard side as I was concerned about the prop wash picking up exhaust on the port side, but it appears that may not be an issue from other's experience. Even with one vent, I still decided to put in a valve to control the airflow velocity at cruise, much more comfortable now.
 
Scratching my head on this one.

For sure.

Planning on making my own overhead for ventilation, lights, GPS antenna mounting purposes. LeoK is sending me his finished female mold for this purpose. Planning a forced-air-over-icepack "air conditioner" for ground ops on hot sunny days at the beach, etc. Otherwise no A/C and no need anticipated.

Sounds like one NACA (on either side) will suffice for airflow. Questions remain about the need for the buttterfly valve in line. Seems to me that pressurizing the overhead is simpler than running SCAT to each vent. Automobile vents are far cheaper than the machined aluminum eyeball vents, seal more poorly,and probably mandate a butterfly valve for full control, partially offsetting cost. But they come in a much wider array of styles.

I come away from this thought exercise wishing Geoff offered his butterfly servo controller in a single barrel design. I could use one for the NACA outside air vent and another for the icebox AC unit. (Actually, I could use a blend-door setup like cars use for heat-cool mixing, but not sure how to practically achieve that with COTS parts.) Anybody know if the AeroSport unit can be re-clocked as a differential mixing valve, where one barrel opens proportionally as the other one closes?
 
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Bill Boyd said:
For sure.

Planning on making my own overhead for ventilation, lights, GPS antenna mounting purposes. LeoK is sending me his finished female mold for this purpose. Planning a forced-air-over-icepack "air conditioner" for ground ops on hot sunny days at the beach, etc. Otherwise no A/C and no need anticipated.

Sounds like one NACA (on either side) will suffice for airflow. Questions remain about the need for the buttterfly valve in line. Seems to me that pressurizing the overhead is simpler than running SCAT to each vent. Automobile vents are far cheaper than the machined aluminum eyeball vents, seal more poorly,and probably mandate a butterfly valve for full control, partially offsetting cost. But they come in a much wider array of styles.

I come away from this thought exercise wishing Geoff offered his butterfly servo controller in a single barrel design. I could use one for the NACA outside air vent and another for the icebox AC unit. (Actually, I could use a blend-door setup like cars use for heat-cool mixing, but not sure how to practically achieve that with COTS parts.) Anybody know if the AeroSport unit can be re-clocked as a differential mixing valve, where one barrel opens proportionally as the other one closes?
Click to expand...

The barrels are separate. I wouldn't think it would be difficult to rig what you want. I suspect all you have to do is reposition one of the levers.

Although I'm not sure how you would rig an ice box cooler since the valve is behind the baggage bulkhead.

Give Geoff a call a discuss your idea.
 
Butterfly Valve

Another reason I chose to install a butterfly valve in my setup is that without the valve and with all 4 Steinair vents closed, I found that the entire overhead console would exhibit visible buffeting from the pressurization available from the NACA duct at cruise speeds. The buffet ceased with a vent opened. After installing the valve, the buffeting is no longer an issue with the vents closed, and the passengers appreciate the ability to throttle the vent air velocity at any airspeed from taxi to cruise. I built my own valve without too much difficulty. For A/C, I have one of the cool box units and thought about plumbing it onto the overhead, but then I started flying and, well you know the rest... maybe at the next condition inspection...
 
So I ordered 2 additional rear vents and fitted them on either side just above the height of the rudder pedals . I have a push pull rod attached for activation. I have instant air flow once the prop turns. No annoying squelch break-through from the NACA ducts. Cooling to the instrument panel as well. Abundant air flow , way better than the NACA's in my opinion.
 
NACA Vents/Overhead Console

Jack in Michigan, I have 2 NACA vents, no butterfly valve and do find a bit of a draft that comes from the OH console access hatch on cold days (similar temps to you). Bear in mind I have a home made console so my engineering may not be up to Aerosports standard. In my case one vent would likely have been enough. A gasket around the hatch has helped but I will likely add a butterfly valve at some point.
Rick
#40956
Southampton, Ont
 
David Paule said:
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
Click to expand...

David,
Actually behind the doors where the passenger air vents are located might be a low pressure area. I witnessed that when going fast ~180 kts my rear air vent was sucked open.
Mike
 
The Aerosport NACA valve controller could be made to open one valve and close the other. Also Our new AEROVENTS seal off the air about 99% or more when closed.

Just an FWIW
I have 2 NACA scoops feeding my overhead and while on the ground with the engine running and valve wide open I do get airflow thru the console and it is better than no air. The air you get is enough for some relief. On hot days I have the valve wide open on the ground and once I get to about 1000 ft AGL I close it down to about have and then adjust eyeball vents to each passengers comfort. I flew my airplane for about 3 months in the winter here in Ohio before installing the valve. I had the valve completed and ready to install before the first flight but I thought maybe I will not need this. Well after flying it for 3 months in the winter I decided to install it. The big difference is in the winter you do not want that cold air inside the overhead console. It really does make the cabin Colder. Being able to shut the system down is very nice. Another advantage is that a couple times (before valve) I had passengers in the rear and they had the vents open and then the next time I flew it was colder out and the cold air was coming in thru the rear vents and it was not easy to try and close them while in the front. With the valve you can close the system down. I find the NACA controller a very necessary item when you have an Overhead console especially if you live somewhere were the temperature does not get above 60 in the winter. I do feel that 2 NACA scoops are better than just one. But that is from my personal experience.

These are just my thoughts and experiences from flying my RV-10 for 7 1/2 years. If I built another RV-10 I would repeat what I have now for the overhead and valve.
 
Fan assistance for ventilation while taxiing?

I am not claustrophobic but I hate to be in a small hot space without air flowing freely over my face. I anticipate problems in southern latitudes when I eventually get there, especially as my tip-up will be a little more difficult than the slider models to just crack open.

So, I was wondering about putting an electrical fan in-line with the panel vents. There is a kit by Lonestar but at $389, I think I would just put up with the problem. I have 2" pc fans in stock but I doubt if they have enough oomph.

Has anybody experimented with a roll-your-own electrical forced ventilation system? Please tell us how you did it and how it worked out.
 
Loman said:
I am not claustrophobic but I hate to be in a small hot space without air flowing freely over my face. I anticipate problems in southern latitudes when I eventually get there, especially as my tip-up will be a little more difficult than the slider models to just crack open.

So, I was wondering about putting an electrical fan in-line with the panel vents. There is a kit by Lonestar but at $389, I think I would just put up with the problem. I have 2" pc fans in stock but I doubt if they have enough oomph.

Has anybody experimented with a roll-your-own electrical forced ventilation system? Please tell us how you did it and how it worked out.
Click to expand...

I was thinking of doing the same thing. I am a ways out from needing to solve the actual logistics of this though. I live in NC and an extended taxi without AC can get miserable in the summer.
 
Cabin ventilation

Joe, I've only got one standard Vans Naca vent located just behind and to the top of the baggage door feeding my homegrown overhead console with four Vans Black Plastic vents. No problem with getting enough air even with all vents open. Others have said they've put only one Naca on the starboard side and it's worked well however I can only speak for mine which has been very successful. So successful in fact that while at Oshkosh I picked up a Control Valve from TCW technologies and will mate that to a Shut off Valve from ASpruce (08-07305) to be able to shut off all air to the console when at sub zero etc. cheers from Western Australia
 
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