S

Short Fuse

Member
So I've been doing some research on the idea of heating for the back seat on the -8. Since there seems to be no ideal way of running Scat to the rear seat...it got me thinking. Why could one not install an electric heating unit for the passenger. They make units for vehicles that run on 12v and approx 10 amps. I know you may have to watch your load a little more, and/or go with a higher output alternator, but it seems like something should be able to be engineered. I also know these units aren't all that efficient, but it is surely better than nothing. However, more than likely I'm overlooking something or else everyone would be doing this. Any thoughts??? Thanks
 
This sounds like a good time to get familiar with the "search" function in the forum.

Take a look here also.
 
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Using the search function rarely results in the desired outcome. Normally I find everthing but what I'm looking for. I've been on Mike's site before and have seen his method. I would just rather come up with a system that doesn't require cutting holes in semi-structural members. I understand that he hasn't had any problems with his method, I'm just looking for alternatives.
 
Go for it.....

I have an electric seat heater element in both front and back seats. The electrical load is in fact negligible, though toasty warm. I used M Benz heaters, but in the backrests only, not the squab under your bum.

The heating in my -4 runs off the oil cooler, not the exhaust, so sometimes on a long descent you are dependent on electrical heat. If you are flying in less than 20F perhaps a problem, but its coping just fine for me in the UK.
 
Also something that might work well - you can buy heated vests for cold weather motorcycle riding. They are amazingly warm and comfortable and the current draw isn't bad (on max heat, about 70W and you'll not often want max heat). My guess is that you'd get more comfort for less wattage than with a small space heater type device.
 
rear seat heat

I shared your concerns on the spar carry through. What I am doing is a stick boot on the front stick with a 1.5" duct connected to it from a separate heat muff. The control tunnel is lined with thin carpet and the aileron and elevator push tubes have boots to seal the area as well. I made a plate to cover the rear stick opening with two eyeball vents and an opening for a rear stick boot. I had Rich Robins make both my muffs and valves with 1.5" duct connections only because he would not do 1". I have 2" ducting on my RV6 but I started with a 1" hole in the baffle and planned to increase it as necessary. Never have because it is plenty. The bigger the hole the more cooling air taken from the engine and dumped overboard when the heater is not used. Rear seat fresh air is dumped into this pressure chamber via a valve also. Any combination of heat and/or fresh air is possible. Not flying yet but I think it will be sweet. Should have a pirep this winter.
 
DonPro said:
I shared your concerns on the spar carry through. What I am doing is a stick boot on the front stick with a 1.5" duct connected to it from a separate heat muff. The control tunnel is lined with thin carpet and the aileron and elevator push tubes have boots to seal the area as well. I made a plate to cover the rear stick opening with two eyeball vents and an opening for a rear stick boot. I had Rich Robins make both my muffs and valves with 1.5" duct connections only because he would not do 1". I have 2" ducting on my RV6 but I started with a 1" hole in the baffle and planned to increase it as necessary. Never have because it is plenty. The bigger the hole the more cooling air taken from the engine and dumped overboard when the heater is not used. Rear seat fresh air is dumped into this pressure chamber via a valve also. Any combination of heat and/or fresh air is possible. Not flying yet but I think it will be sweet. Should have a pirep this winter.
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I will love to hear how that works out.
 
Robby Knox(Hardknox) has a seat heater in the back of his RV-8 and it was a life saver going out to LOE a few years ago.
 
Another way...

To get hot air to the back without going through the spar carrythrough bulkhead is to put a pair of 90-degree elbows in the corners of the front seat ramp. They dump warm air right onto the passenger's feet and legs.

I used 1.25 PVC, so there is a pipe running under the seat ramp with a Tee fitting in it, and an elbow at each end. a 1.5 scat tube comes from the right side gear tower, under the little floor plate on the side (can't remember the formal name for that, but its the mirror image of the piece that covers the fuel selector on the other side) and connects to the Tee. I cut round holes in the triangular seat ramp ribs. The PVC elbows have a narrow wrap of neoprene foam for cushioning.

When the fuselage gets back from the paint shop and I put it all together, I'll post a couple of pictures. I think it is going to be great for the back seater.

Another thing that helps is to make a place for the air to get out. You can't expect to pump much air into the cockpit, hot or cold, unless you make a place for it to go out. I made two small holes in the turtledeck skin, just inside the canopy skirt, that allow air to flow back into the tail cone. Another poster in the archives went so far as to put an exhaust hole in the belly that was connected to these vent holes. I think that once the air makes it into the tail cone, it can find its way out along the elevator hinge line and rudder cable holes. But I may yet also put an exhaust port back there.
The other good thing about putting the vent holes in the back area of the canopy is that it will ( hopefully) scavange off the cold draft that comes in under the canopy skirt back there. Just getting rid of that draft will be a big plus for the passenger, and will allow front-seat heat to flow back aft as well.

Stay tuned. BTW, anyone think of a way to do this with parts that are lighter than PVC plumbing fittings, I'm open to suggestions. I'm thinking about molding some glass parts, but....I'll test out the idea with PVC first.
 
heated seats vs air?

For those of you with more experience, what's better, hot air or heated seats? My only concern with heated seats is you might have a hot a$$ with cold hands and feet...

FWIW, we spent $500 to add hot air to the back of our Citabria...worth every penny! I assume the RV-8 will be similarly cold without it...
 
I haven't tried to extend heat to the back of the -8 (living down here in Texas and all), so my comments probably don't mean much, but my experience with the standard heater says that it is going to be hard to get enough "Therms" of heat (from the standard heat box) to both the back and front seats to make both people comfortable. I flew the Val up to Minnesota in February, and got pretty chilly when the temps dropped below zero, and that was with ALL the heat going to me alone in the front.

If I were doing back seat heat, I'd probably go electric with either a seat heater or vest. Neither will get the passengers feet, but if the pilot is nice, the front seat heat might spill around to help keep their toes warm. Remember that the sidewalls can get pretty cold, and conduction through the skin will make some real cold spots as well.

The best thing you can do is fly on a sunny day - that bubble canopy is a solar oven!

Paul
 
Rear seat heat

I used a very simple method to deliver cabin heat to the rear seat of the Doll. I put the battery in the back, therefore the firewall had room for the heater box where the battery would mount in the front. I placed it so a two inch scat tube would pass through the forward baggage compartment just below the shelf. Then I placed a controllable air outlet on the rear wall of the baggage compartment near the top of the right gear tower. The hot air will blow past the pilot between the right side of the seat to the rear cockpit. It blows so hard at cruise speed that you can feel it blowing in the back seat. It heats the entire cockpit well. Ok.... it works well on days that are 40 degrees or above. I only have an eight inch heat muff. I've considered adding a second muff in series, but after 1000 hours, there hasn't been that many days here in Texas that it is needed.



1zlep8n.jpg


2w56lna.jpg

I cleaned the cockpit right after taking this picture.... Man does it ever get dirty down there!
 
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You don't notice cold hands and feet when using a heated vest. I think it has something to do with maintaining core body temperature. I used one under a motorcycle suit to fly acro in a Maxair Rocket during the Alabama winter, meaning down to 45F or so. May not sound very cold until you realize the Maxair has no enclosed cockpit, and airspeed can reach 110. Hands and feet were happy in Reeboks and plain uninsulated gloves.



The new -8 won't have a heat muff, firewall holes, or scat tube spaghetti, just seat base heaters and electrical plugs for heated vests. I'm pretty sure I'll be warm enough even if the canopy blows off <g>
 
Yep, I've done 10's of thousands of miles in subfreezing temps on an unfaired bike and nothing keeps my hands and feet warm like a heated vest. My hands and feet (lightly insulated gloves, uninsulated boots) would start to get cold when temps got into the 20's. I added heated hand grips and that pretty much solved that problem (also useful for de-icing the throttle). I think that without the constant 80mph wind that I get on the bike, you could be very comfortable in an RV with just the vest and perhaps some light gloves and warm socks, at least in southern climates. I imagine that flying at altitude in the north in the winter could get rather cold! When I finally build an RV (I'm a student and part-time student pilot now) I would likely add heat as I'd like my passenger to be comfortable and I'd likely be flying in the rockies in the winter.
 
DonPro said:
I shared your concerns on the spar carry through. What I am doing is a stick boot on the front stick with a 1.5" duct connected to it from a separate heat muff. The control tunnel is lined with thin carpet and the aileron and elevator push tubes have boots to seal the area as well. I made a plate to cover the rear stick opening with two eyeball vents and an opening for a rear stick boot. I had Rich Robins make both my muffs and valves with 1.5" duct connections only because he would not do 1". I have 2" ducting on my RV6 but I started with a 1" hole in the baffle and planned to increase it as necessary. Never have because it is plenty. The bigger the hole the more cooling air taken from the engine and dumped overboard when the heater is not used. Rear seat fresh air is dumped into this pressure chamber via a valve also. Any combination of heat and/or fresh air is possible. Not flying yet but I think it will be sweet. Should have a pirep this winter.
Click to expand...

Do you have any pics of this that you could post? Thanks!
 
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