Cabin heat with an Aerovee - another approach
Posted: Sun Dec 17, 2023 5:56 pm
by Bryan Cotton
Hi all,
If you remember I was chasing hot oil issues this summer. I came up with a plenum behind the oil cooler, and two 1.75" scat tubes going to reverse scoops on the bottom of the cowl.
(edit: I had the wrong link here before)
viewtopic.php?f=7&t=7279&start=20
Then winter came and all my temperatures were too cold. I did some blocking of the air inlet and got the temps toasty, but well within limits.
viewtopic.php?f=7&t=7498
Seems to me that I could intercept some of that air leaving the oil cooler and heat the cabin. I started making a heater valve body out of 0.016 aluminum.
Screenshot_20231217-121400-868.png (392.59 KiB) Viewed 10528 times
For the flapper valve, I am going to use stainless. I also want the hinge to be stainless for fire safety. I bought these hinges:
https://www.amazon.com/gp/aw/d/B093LKF4JL
They are a pain to drill. The hinge is a little sloppy but a real hinge pin can be substituted and it tightens things up.
I made a prototype setup using an aluminum flapper valve. On either side I bent a small return flange. It took me a couple of tries to figure out sizing so it moves freely but has minimal gaps. Video:
My concept is to have the bowden cable inside and work directly on the door. When closed the hot air will pass right through to the reverse scoop. When all the way open all the airflow will go into the cabin. I’ll have a deflector to push the air down and serve as a mount for the bowden cable.
Old threads for reference:
viewtopic.php?f=7&t=5366&p=40644
Re: Cabin heat with an Aerovee - another approach
Posted: Sun Dec 17, 2023 9:30 pm
by BRS
I like the idea of using heat from the oil cooler. Just be cautious about Carbon Monoxide. Do you have a detector in your cabin?
Re: Cabin heat with an Aerovee - another approach
Posted: Sun Dec 17, 2023 10:58 pm
by Bryan Cotton
BRS wrote:I like the idea of using heat from the oil cooler. Just be cautious about Carbon Monoxide. Do you have a detector in your cabin?
I had one, I plan on putting fresh batteries in and reinstalling it. I would think there is a lot less risk of CO from the oil cooler, since the exhaust is on the low pressure side of the baffles.
Re: Cabin heat with an Aerovee - another approach
Posted: Sun Dec 17, 2023 11:28 pm
by BRS
Ah, so you have the top mounted oil cooler. For some reason I always think everyone’s plane if built like mine. Hmmm, I must be self centerd. Need to work on that.
Re: Cabin heat with an Aerovee - another approach
Posted: Mon Dec 18, 2023 12:37 am
by daleandee
Bryan Cotton wrote:Seems to me that I could intercept some of that air leaving the oil cooler and heat the cabin. I started making a heater valve body out of 0.016 aluminum.
FWIW … viewtopic.php?f=8&t=6505&p=49377&hilit=oil+cooler+heat#p49377
Dale
3.0 Corvair/Tailwheel
Re: Cabin heat with an Aerovee - another approach
Posted: Mon Dec 18, 2023 8:57 am
by Bryan Cotton
Thanks Dale! I remember that now. Wes did you use a conventional cabin heat valve? It will be interesting to see how the stock VW oil cooler works for heat compared to the real aviation oil cooler.
Re: Cabin heat with an Aerovee - another approach
Posted: Mon Dec 18, 2023 11:25 am
by WesRagle
Good Morning Bryan,
Bryan Cotton wrote:Thanks Dale! I remember that now. Wes did you use a conventional cabin heat valve? It will be interesting to see how the stock VW oil cooler works for heat compared to the real aviation oil cooler.
Yes. The valve is a purchased part as seen in this photo.
Hope it works out for you.
You can join these guys in experimenting with using the oil cooler for cabin heat as can be seen in this video at about the three minute mark .
https://www.youtube.com/watch?v=VmPNRMDD1ZU&t=160s
Good Luck,
Wes
Re: Cabin heat with an Aerovee - another approach
Posted: Sat Dec 23, 2023 3:53 pm
by Bryan Cotton
Progress pics:
hose trial fit heater.png (550.62 KiB) Viewed 9509 times
final riveted valve body.png (483.58 KiB) Viewed 9509 times
Re: Cabin heat with an Aerovee - another approach
Posted: Sun Dec 24, 2023 3:09 pm
by Bryan Cotton
Heater valve:
Re: Cabin heat with an Aerovee - another approach
Posted: Thu Dec 28, 2023 10:20 pm
by Bryan Cotton
Control Cable for heater valve:
Re: Cabin heat with an Aerovee - another approach
Posted: Sun Jan 07, 2024 1:43 pm
by Bryan Cotton
I’ve made some more progress on my heat installation. A big problem was where to mount the heater control knob. I had very little panel real estate. It looked like I could mount it to the left of the trim wheel, so I 3D printed a mockup and taped it in place. One attempt to use the trim and that was shown to be unworkable. I have a real vernier type mixture control, which uses a huge nut to fasten it to the panel. The body of the mixture is an approximately 1/2" OD steel housing. So I thought I would try to use an adel clamp and mount it to the mixture under the panel. Here is the bracket:
means for holding heater cable.png (494.33 KiB) Viewed 2927 times
Before I made it all nice, I tried it in place. Seemed pretty good.
Heater knob mounted temporarily.png (643.33 KiB) Viewed 2927 times
The black heater knob was actually a choke cable from Amazon: https://www.amazon.com/dp/B07NQ6RNPJ
It was hard to see under the panel, so I painted it white and turned the choke icon into an ‘H’ for heat.
Painted heater knob.png (452.32 KiB) Viewed 2927 times
Here is a closeup of my flapper, clevis and swivel. The flapper and clevis are stainless. I bought some titanium off of ebay for the flapper, but it snapped when I tried to bend it in my sheetmetal brake. Back to stainless! Also the hinge is a stainless hinge I bought off of ebay. I took it apart and got two sections with no screw holes, so I could put in my own rivet holes.
flapper with stainless clevis.png (504.33 KiB) Viewed 2927 times
Here are both ends of my cable mount cleaned up. They are 7075-T6 angles that I had in the junk box. The cable sheath grabber is stainless. First I made the rounded hat section around a drill bit,using the vise. Then I cut off a little piece of an AN3 bolt that was a little shorter than the hat section so I could form the ends around it. It seems to hold the spiral sheath really well when socked down.
Heater parts.png (615.88 KiB) Viewed 2927 times
I can’t remember how many pictures per post is allowed so I’m going to do another post for part 2.
Re: Cabin heat with an Aerovee - another approach
Posted: Sun Jan 07, 2024 1:56 pm
by Bryan Cotton
So the big dilemma is locating the parts before drilling holes in the firewall. I had these things to consider:
- Clearance for my feet
- Clearance for the control cable with respect to the rudder pedals
- Clearance on the engine side of the firewall
I took my drill template, temporarily riveted the cable end bracket to it, and taped it in place. Seemed ok from the inside, so I used a center punch to mark where I would be holesawing the 1.75" hole. Then I marked the firewall on the engine side with a sharpie on the center punch dent. I taped my simulated firewall that was in my videos to the real firewall. I taped a piece of paper to the 1.75" hole with a hole in the center, and centered that on my mark. Immediately I had clearance issues. The valve body hit the engine mount. Also my mixture cable was going right through the air inlet tube. So I figured I could move it up about 5/8", and inboard about 1/4". I tried that out and it seems good.
prototype cable routing.png (483.66 KiB) Viewed 2924 times
For attaching the valve body, I put nutplates on it. Would be a major pain to put nutplates in the firewall with the floor installed. So I’ll have to screw it on from the inside. I’m using #8 screws.
valve body with nutplates.png (505.29 KiB) Viewed 2924 times
Two of the mounting screws pick up this deflector I made. Idea is to send the hot air largely downwards, rather than shooting directly out.
deflector.png (508.89 KiB) Viewed 2924 times
So I am about to pull the trigger on this and install it. So far my parts weigh 0.256 lbs, minus the control cable, 6 screws, 4 rivets, and a short piece of scat tubing. So probably about 1/2 lb. If I can save that in clothing I have to wear then I have definitely won!
Re: Cabin heat with an Aerovee - another approach
Posted: Sun Jan 07, 2024 5:50 pm
by BobDz
Looking forward to a success story.
Re: Cabin heat with an Aerovee - another approach
Posted: Fri Jan 12, 2024 3:36 pm
by Bryan Cotton
BobDz wrote:Looking forward to a success story.
Thanks Bob!
My deep holesaw was too big to get on either side of the firewall with my drill. So I bought a low profile holesaw. I took my drilling template to a piece of plywood, and made some pilot holes for woodscrews, Plus I also piloted the 1/4" hole for the holesaw, and for the top mounting hole I brought it up to #18. This let me hold the plywood in place with an AN4 and a #8 screw while I installed the lath screws from the other side.
plywood backup from outside.png (678.67 KiB) Viewed 2699 times
I replaced the drill bit with an AN4 bolt, since I already had the guide hole in the firewall and plywood. Success!
hole sawed.png (276.2 KiB) Viewed 2699 times
Took off the plywood, and deburred the hole. Now I need another set of hands to dimple a couple of rivet holes.
plywood removed.png (266.07 KiB) Viewed 2699 times
In case anybody was wondering, drilling stainless still sucks. This is especially true when you have no room. The first #40 pilot holes were the worst. I had to drill 11 of them.
Re: Cabin heat with an Aerovee - another approach
Posted: Sat Jan 13, 2024 1:15 am
by Bryan Cotton
In theory, I’ve almost got heat.
flapper closed.png (598.38 KiB) Viewed 2655 times
flapper open.png (640.66 KiB) Viewed 2655 times
valve body mounted.png (704.38 KiB) Viewed 2655 times
valve body mounted underneath.png (691.25 KiB) Viewed 2655 times
hose routing to valve body.png (640.44 KiB) Viewed 2655 times
deflector installed.png (618.21 KiB) Viewed 2655 times
Total weight added is 0.5 lbs. A half pound.
Re: Cabin heat with an Aerovee - another approach
Posted: Sat Jan 13, 2024 1:20 am
by BRS
Question: So during the winter when you most need the cabin heat, yet need less oil cooling (don’t some folks block off the oil cooler in winter) is there still enough reserve oil heat to warm the cabin without cooling the oil too much?
Re: Cabin heat with an Aerovee - another approach
Posted: Sat Jan 13, 2024 2:00 am
by Bryan Cotton
BRS wrote:Question: So during the winter when you most need the cabin heat, yet need less oil cooling (don’t some folks block off the oil cooler in winter) is there still enough reserve oil heat to warm the cabin without cooling the oil too much?
Same cooling. The air after the cooler is divided between the cabin and the reverse scoop. I am probably going to block off half of the oil cooler exit. That would be the left side oil cooler exit.
Re: Cabin heat with an Aerovee - another approach
Posted: Sat Jan 13, 2024 12:01 pm
by Bryan Cotton
Bryan Cotton wrote:
BRS wrote:Question: So during the winter when you most need the cabin heat, yet need less oil cooling (don’t some folks block off the oil cooler in winter) is there still enough reserve oil heat to warm the cabin without cooling the oil too much?
Same cooling. The air after the cooler is divided between the cabin and the reverse scoop. I am probably going to block off half of the oil cooler exit. That would be the left side oil cooler exit.
I think the real answer is - we will see! I’ll report back if the weather is ever flyable again. Thinking of starting the annual.
Re: Cabin heat with an Aerovee - another approach
Posted: Sat Jan 13, 2024 8:27 pm
by Bryan Cotton
If you remember, I have two reverse scoops to pull air out of the oil cooler exit plenum. For the Arctic temperatures we are experiencing, I made this easily removable block off plate for the left side. The cabin heat exit is plumbed to the right side.
Screenshot_20240113-182234-033.png (497.3 KiB) Viewed 2531 times
Edit: this is intended to reduce oil cooling and keep the temperatures up.
Re: Cabin heat with an Aerovee - another approach
Posted: Mon Jan 15, 2024 9:02 pm
by Bryan Cotton
Adam was off today for MLK day and was the first to fly with the heat. Ambient temperature was only -3F. In Celsius (for the Canadians, Europeans and Australians), that is frigging cold. Oil temps maxed at 145F during a climb to 2500’ MSL, or 1700’ AGL. Otherwise oil temps were 130-140. But he did report he could feel heat during full power climbs. Not as much in cruise. Oil temp is too cold, despite my inlet blockoff plates.
I am going to add some blockoffs on the exits, and try to get temps up. Considering he felt anything at -3F, it seems promising to me.
And, Adam has discovered the ultimate Aerovee performance enhancement. At a density altitude approaching -4000’, he said it climbs better than a 180HP Skyhawk, solo, in the summer.
Re: Cabin heat with an Aerovee - another approach
Posted: Mon Jan 15, 2024 9:09 pm
by BobDz
Success!
Re: Cabin heat with an Aerovee - another approach
Posted: Mon Jan 15, 2024 11:57 pm
by Bryan Cotton
BobDz wrote:Success!
Success, but not victory. Victory is needing to shut down cabin heat some to be comfortable. If I can get the oil temp back to 160-180, I think I will achieve victory.
Good thing you have all those lakes around you to moderate the temperatures, so you will never need to go through this.
Re: Cabin heat with an Aerovee - another approach
Posted: Tue Jan 16, 2024 9:22 am
by BobDz
Bryan Cotton wrote:
BobDz wrote:Success!
Good thing you have all those lakes around you to moderate the temperatures, so you will never need to go through this.
The lakes do not appear to be doing their job. It was -10 when crazy puppy and I went for our walk this morning.
Re: Cabin heat with an Aerovee - another approach
Posted: Thu Jan 18, 2024 12:03 am
by Bryan Cotton
I’m trying to get my temperatures up some more. Here I am blocking off a portion of the outlet. This is what I made:
Screenshot_20240117-211259-130.png (389.37 KiB) Viewed 1691 times
It picks up the lower hinge pin and then installs with one screw.
Screenshot_20240117-211318-498.png (405.9 KiB) Viewed 1691 times
Re: Cabin heat with an Aerovee - another approach
Posted: Thu Jan 18, 2024 12:09 pm
by Bryan Cotton
I flew for an hour today. 16F out, oil temp was 165. Sufficient but some room for improvement.
Re: Cabin heat with an Aerovee - another approach
Posted: Sat Jan 20, 2024 2:02 pm
by Bryan Cotton
Flew 0.6 today, I think it was -2F on the ground (edit: metar history shows 2-6F). I added this additional blockoff to the cowl exit:
Screenshot_20240119-211421-766.png (637.63 KiB) Viewed 1548 times
Climbed to 4500’, oil temp stabilized at 165 in cruise. During descent it came down to 155, either if I dove to a higher airspeed or pulled power back. Down by my feet the temperature read 48, and was about 38F on the seat. CHTs were 160-170. They were over 200F in climb.
I also pulled off the orange electrical tape from the wing roots. That tape is a few years old and is shot. I re-taped it with wider 1" tape and reduced the air leaks considerably. I think I’m declaring success. We are going to fly tomorrow and it is supposed to get to 20 as the day’s high. I’m leaving the blockoff configuration as is and I’m predicting 185-190F oil temps. If it gets too hot it is only one screw to step down in the blockoff of the outlet, to the prior configuration.
Edit: This new plate screws to the prior plate I showed with 1 screw. The first plate now has a nutplate. The new one hooks onto the hinge pin near the center, where there are no hinge loops. Otherwise it rests on the inside of the cowl sort of. I drilled 3 large clearance holes for the rivets that install the first plate to the hinge. So if it is hot, I can land and remove the new plate with one screw and the original plate is still there.