Back-Seat Heat & Cooling

[Voidhawk9]

Two things for context, first:

I'm part-way through building the rear heat-duct, so if I want to have heat from here to the back seat area, now would seem to be the time to install provision for this.

I'm installing a liquid-cooled engine, so will be able to install an automotive style heat exchanger for cockpit heat. I'll also be using this duct for cool air, and varying the temperature by varying the coolant flow through the heat exchanger, much as it is commonly done in a car. I considered simply ducting air from behind the radiator, P-51 style, but I can't be sure there would be enough heat for warming the cockpit of a 4-place. But I'm not there yet, just working on the heat duct!

 

Has anyone made any provision to supply heat to the back-seat area from the heat duct? I have not come across anything in my research, yet. 

I was thinking about installing vents in the side of the heat duct near where it meets the seatback support (for the front seat), aimed forward under the front seatback area. With the aforementioned heat exchanger, there will be plenty of heat available, so no concerns about a lack of heat for the front seat area. I plan to have the cockpit air outlet aft, so the warm air should then flow back over the back seat passengers.

 

Any suggestions, recommendations, or prior experience, please?

[Kent Ashton]

It doesn’t take much heat to make a Cozy tolerable at say, 15000’ and 0 deg C. There is a lot of solar energy through the canopy.  We just use the wimpy plans heat to take the chill off our feet and fly with heavy cotton pullovers.   A well-sealed cockpit almost negates the need for heat.  I wouldn’t like to carry around an arctic-grade heat system I might only need once or twice a year.  Better to just wear two pairs of wool socks.

Nevertheless, my Ford Ranger heater (in my truck) will blast me out at full hot,  even in cold wx so I would guess that a heat exchanger half that size would be quite enough for a Cozy

However, high heat rises to the top of the truck cab and a hot head isn’t comfortable.  Less heat but directed around feet works better with a clear canopy—or wear two pairs of socks twice a year and build a light aircraft.  

Light airplanes are not sufficiently  appreciated.

 

Edited August 27, 2018 by Kent Ashton

[Jon Matcho]

9 hours ago, Kent Ashton said:

Light airplanes are not sufficiently  appreciated.

Thanks for the reminder Kent!  This is one of the guiding principles of Rutan's aircraft designs.

9 hours ago, Kent Ashton said:

A well-sealed cockpit almost negates the need for heat.

That's my takeaway here.

[macleodm3]

16 hours ago, Voidhawk9 said:

Has anyone made any provision to supply heat to the back-seat area from the heat duct? I have not come across anything in my research, yet. 

Putting vents / holes in the heat duct may not be OK...  it also serves as the keel / center structural member.  The plans state "The center keel provides strength for the fuselage and contains the hot air duct. It forms the base of the center control console and contains hard points for mounting the safety belts."

If you determine its OK to put vents or holes in to the center keel / heat duct, then it would be EZ to install two eyeball vents where the rear passengers can reach them.

The plans design uses the higher air pressure inside the lower engine cowl to push hot air through the heat duct up to the front of the plane.  What pressure are you planning to use to get air to flow through your heat duct?

Edited August 27, 2018 by macleodm3
hmmmm.

[Voidhawk9]

On 8/26/2018 at 10:27 PM, Kent Ashton said:

It doesn’t take much heat to make a Cozy tolerable at say, 15000’ and 0 deg C...

Light airplanes are not sufficiently  appreciated.

1

Thanks for that. I'll keep it small and light then, or reconsider simply ducting the warm air from behind the rad.

21 hours ago, macleodm3 said:

Putting vents / holes in the heat duct may not be OK...  it also serves as the keel / center structural member. 

The plans design uses the higher air pressure inside the lower engine cowl to push hot air through the heat duct up to the front of the plane.  What pressure are you planning to use to get air to flow through your heat duct?

2

I won't be carving it up, just an outlet on each side, perhaps 1" diameter. 

I intend to have a small duct off the inlet diffuser to provide the pressure. The inlet will be a ram-air type suitable for feeding the radiator, not a NACA duct.

[Jon Matcho]

On 8/26/2018 at 10:27 PM, Kent Ashton said:

Light airplanes are not sufficiently appreciated.

It's good to receive reminders as to why we chose to build a Rutan-designed/inspired plans-built aircraft.  These planes are cross country fuel efficient aircraft.  Sure, there's room to load them up and add weight, but at the expense of efficiency.  I am now more into watching GPH than MPH.