Kitfox Aircraft Stick and Rudder Stein Air Grove Aircraft TCW Technologies Dynon Avionics AeroLED MGL Avionics Leading Edge Airfoils Desser EarthX Batteries Garmin G3X Touch
Page 1 of 2 12 LastLast
Results 1 to 10 of 14

Thread: Rotax cabin heat: How good is it?

  1. #1

    Join Date
    May 2017
    Location
    NH
    Posts
    13

    Question Rotax cabin heat: How good is it?

    Hey guys I wanted to ask some of you Rotax owners how good your cabin heat is? If anybody has concrete numbers that would be even better, such as "the outside air temp was X and my cabin temp was Y". I flew with Finn (Dorsal) and he mentioned it was enough to keep the chill out on a cold day. He also mentioned the lengths you go to seal up the cab make a big impact.

    I am a bit spoiled now as I fly in an older 6 cylinder cessna that will bake you out of the cab. But I am really curious as to how the kitfox with a factory heater would do in the frigid weather?

    Thanks in advance!
    Flying a 1965 Cessna 172 for now - it is a 6 cylinder Conti so at least she runs smooth and has the heat to cook you out of the cab even on the coldest winter day!

  2. #2
    Senior Member
    Join Date
    May 2011
    Location
    MN
    Posts
    469

    Default Re: Rotax cabin heat: How good is it?

    I also have/fly an older 172 with the O-300, great engine and plane that I have owned for 30+ years.
    My other toy (plane) with the Rotax has a barely usable heater. Mine only has muffler type heat and in the very cold winters we have up here (northern MN) it is almost non-existent heat. I have been meaning to put in a small heater core that uses the coolant for better heating, but just never seem to remember doing it until it gets too cold in the hangar to do the work.
    Definitely install a couple of the 'Earls' type heat exchangers if you are wanting to fly in the cold.

  3. #3
    Senior Member Slyfox's Avatar
    Join Date
    Dec 2008
    Location
    felts field, spokane
    Posts
    1,327

    Default Re: Rotax cabin heat: How good is it?

    the heat is as good as what you can keep out. meaning, how you seal up the cold from coming in.
    I don't use the water heater. I put a funnel on the back side of the radiator and scat tube it into the cabin. works great. you have to block off most the radiator to make good.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  4. #4
    Senior Member Dave S's Avatar
    Join Date
    Oct 2008
    Location
    St Paul, MN
    Posts
    1,833

    Default Re: Rotax cabin heat: How good is it?

    ...310R

    Slyfox is absolutely correct...the cabin has to be sealed well enough. The S7 has a much better door seal system than the early KFs which had round tubes for door frames and a little harder to seal - so you also have to think about which KF version you want to keep warm.

    On the 7, there are a number of things a person can do to keep the cabin cozy.
    1) How good a job the builder does in fabricating and installing the doors and door P-seals is an obvious factor
    2) The flaperon horn holes in the turtle deck can be sealed up - I used some small aluminum panels with 1/4" felt.
    3) The forward floor and boot cowl edges can be a source of leaks (sucking the air out of the cabin which is replaced by cold air coming in elsewhere)
    4) a lot of cold air can come in through the back between the seat and baggage bay from the tail - depending in construction.
    5) The wing roots can be a source of drafts

    With a few points of attention to these items, we find that the cabin will stay comfortable (55 - 60 F) in the OATs we fly in during the winter ( zero to minus 5 F) Anything around 20 - 30F - we cycle the heater fans to keep from cooking.

    I don't think it is simply a matter of the rotax cabin heat or not - I believe there have been different sized heater cores over the years, certainly the current kitfox models are better sealed than the earlier ones and it does matter what kind of attention to detail was done in the build with regard to sealing. Then there is the issue of what coolant temps are normally maintained in a particular plane due to choice of coolant, type or radiator, cowl design. oil cooler location, etc.

    Aside from those details, am I warm enough? - yes, happy with the system - definetly. I don't fly when it is colder than 10 below zero F so I can't say I know much about the affects of really, really cold temps.

    Sincerely,
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  5. #5
    Senior Member Slyfox's Avatar
    Join Date
    Dec 2008
    Location
    felts field, spokane
    Posts
    1,327

    Default Re: Rotax cabin heat: How good is it?

    just a note on electronics. I don't fly my fox below 25. I save that flying for the rv. if colder then about 5 degrees f the dynon d180 won't fire up. I have a mixture of steam and glass, so this doesn't keep me from flying. I'll take off and in flight generally when things warm up the dynon will come on, just something to think about in real super cold ops.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  6. #6
    Senior Member av8rps's Avatar
    Join Date
    Oct 2009
    Location
    Junction City, WI
    Posts
    680

    Default Re: Rotax cabin heat: How good is it?

    Whether a Continental, Lycoming, or a Rotax, your plane needs to have air leaks contained (especially in the tail, right behind the cabin, as well as pressurized air coming into cabin) if you are to keep whatever heat you have in. Especially a fabric covered plane, as the cold and heat goes right through the fabric.

    Exhaust temps on a Rotax is the same as any other gas engine, right around 1400+ degrees. So what kind of a heat muff you have on your exhaust pipe is the biggest factor there.

    And if the heat muff you make doesn't give you enough heat, then add another from the other side of the exhaust (something you can't do legally on a factory built plane). And if that still isn't enough, take the heat right off the header pipes and put extra springs or coils in the muffs to retain more heat (that alone can make a huge difference).

    And if you want even more cabin heat, add a heater core (or two) to your 912 in addition to the heat muffs. Or if you live in the Yukon, put a school bus heater core under your panel . Yes, a 912 will run a bus heater core without a problem. It will be heavy, but you'll have lots of heat.

    Also, make sure you fly with a 180 degree thermostat (or radiator shutters) so you can keep your 912 hot on those extra cool days. Now your plane is just like your car (actually better because you also have 2 heat muffs in addition to the heater core, which you can make as big or small as you want )

    And if that still isn't enough heat for you because you live north of the Yukon, capture all the hot air from the back side of the engine radiator and duct that into the cabin too (that's all I used on my Avid Flyer and even without a sealed cabin it was pretty good. I didn't need gloves unless it was below 10 degrees OAT).

    With all that said, remember, you can't do any of that to a Cessna, a Piper, etc. Or at least legally. Oh, and not every factory built airplane has good heat like your 172. Talk to a few J-3 pilots and I'm sure they will confirm...

    A friend of mine did a few things that I suggested above to his Avid Flyer years ago and he ended up moving the heat vents up into the cabin because the heat literally melted his boots on a 10 degree day. He had so much heat he never bothered to seal everything up like he should have (I personally would work first at sealing air leaks as I feel that is the best thing to do to minimize your need for a high volume of heat).

    Bottom line, you do everything mentioned above and you will have way more heat than that Cessna. And since it is a homebuilt, if you don't like your result you can just keep adding muffs, heater cores, fans, more cabin sealing, etc. So you'd only have yourself to blame if your cabin is still cold.

  7. #7
    Senior Member Slyfox's Avatar
    Join Date
    Dec 2008
    Location
    felts field, spokane
    Posts
    1,327

    Default Re: Rotax cabin heat: How good is it?

    mentioning keeping cold out. what I do on my 4 is remove the cowls and take some clear plastic, not to thick, and wrap from the firewall to the wind screen. I tape around the windscreen down the side and then put the cowls back on. at the firewall I kind of go over the top and wire tie the plastic to the motor mount. ha! like you said, can't do that to a certified. we be lucky ducks. this really works, generally I feel wind on my hands when flying in the summer, I like it. but in the cold, yuk. this keeps the wind out. I also sealed up at the wing roots with fabric. that helped a lot also. haven't done anything in the back. drafty back there. I'm good down to 25 after that, it's rv time.
    steve
    slyfox
    model IV 1200-flying
    912uls
    IVO medium in-flight
    RV7A-flying
    IO-360
    constant speed prop

  8. #8

    Join Date
    May 2017
    Location
    NH
    Posts
    13

    Default Re: Rotax cabin heat: How good is it?

    Quote Originally Posted by WWhunter View Post
    I also have/fly an older 172 with the O-300, great engine and plane that I have owned for 30+ years.
    They are great planes with that conti 300! More maintenance and weight due to the two added cylinders, but they heat amazing and run nice and smooth even at idle with carb heat applied.

    Quote Originally Posted by Dave S View Post
    With a few points of attention to these items, we find that the cabin will stay comfortable (55 - 60 F) in the OATs we fly in during the winter ( zero to minus 5 F) Anything around 20 - 30F - we cycle the heater fans to keep from cooking.
    Thank you for the numbers Dave, that is EXACTLY what I was looking for! Good to know if the cabin is buttoned up you can still remain comfy in there.

    Quote Originally Posted by Slyfox View Post
    just a note on electronics. I don't fly my fox below 25. I save that flying for the rv. if colder then about 5 degrees f the dynon d180 won't fire up. I have a mixture of steam and glass, so this doesn't keep me from flying. I'll take off and in flight generally when things warm up the dynon will come on, just something to think about in real super cold ops.
    That is another point I had thought of but forgot to elude to in this post, thank you for bringing it up. I plan to do a 912is and not 100% sure of the system I will go with but honestly it will probably be whatever Kitfox recommends so I am not in uncharted waters and can call them with any questions. I wonder if some displays will operate in frigid temps? I know many full color displays simply will not. Good thing to factor into my decision though.

    Quote Originally Posted by av8rps View Post
    And if you want even more cabin heat, add a heater core (or two) to your 912 in addition to the heat muffs. Or if you live in the Yukon, put a school bus heater core under your panel . Yes, a 912 will run a bus heater core without a problem. It will be heavy, but you'll have lots of heat.

    Also, make sure you fly with a 180 degree thermostat (or radiator shutters) so you can keep your 912 hot on those extra cool days. Now your plane is just like your car (actually better because you also have 2 heat muffs in addition to the heater core, which you can make as big or small as you want )

    And if that still isn't enough heat for you because you live north of the Yukon, capture all the hot air from the back side of the engine radiator and duct that into the cabin too (that's all I used on my Avid Flyer and even without a sealed cabin it was pretty good. I didn't need gloves unless it was below 10 degrees OAT).
    I really appreciate the detail and knowledge from somebody with experience. I am actually kinda planning on being in AK at some point in my Air Force career so I may need to add a heat shroud as well, cross that bridge when I get there. I would love to be stationed in AK for a few years but the old lady has already voiced STRONG opposition hahaha I keep telling her the AF doesn't care about her dislike of cold....

    Dave S: Thank you for listing specific things to do during the build to button up the cab! I will definitely be referencing back to these!
    Flying a 1965 Cessna 172 for now - it is a 6 cylinder Conti so at least she runs smooth and has the heat to cook you out of the cab even on the coldest winter day!

  9. #9
    Lawdog's Avatar
    Join Date
    Apr 2018
    Location
    Colorado
    Posts
    19

    Default Re: Rotax cabin heat: How good is it?

    The cabin heat in my Series 7 Sport with 912 ULS is very good. Not sure what heater core is installed but is about 6x12” w 2 fans. I can use either 1 or both fans. A recent cold morning flight air temps were 18-20F, the cabin was warm enough to fly without a jacket or gloves..

  10. #10
    Senior Member efwd's Avatar
    Join Date
    Jun 2015
    Location
    Yorba Linda, CA
    Posts
    2,817

    Default Re: Rotax cabin heat: How good is it?

    Dang, guess I'm going to need to fly high or far from my home in Southern CA to make use of the heater....
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •