Cold cabin

[Guest]

Looking for any suggestions on warming up the cabin of a Bravo GX. My customer from northern Ontario has a very uncomfortable ride in colder weather.

We've insulated all of the Scat ducts in an effort to help, but so far still cold.

Thanks,

Clarence

[Marauder]

Looking for any suggestions on warming up the cabin of a Bravo GX. My customer from northern Ontario has a very uncomfortable ride in colder weather. We've insulated all of the Scat ducts in an effort to help, but so far still cold. Thanks, Clarence

Any possibility of using an external heater? I use one of these gizmos with a portable power pack to warm the cockpit before flying in the winter (my ceramic heater keeps blowing the circuit breaker in the hangar). It will work off of the cigar lighter. http://t.harborfreight.com/12-volt-auto-heater-defroster-with-light-60525.html?utm_referrer=https://www.google.com/ Sent using Tapatalk

[Awful_Charlie]

I'd be very interested in this too - unfortunately warming up with ground heat isn't really effective on flights over an hour or so, and those are the ones where it is more likely to be worth going up high into the cold.  Any electrical heater is going to need to be a 24V model, and even 20amps is only going to make 500W which might start to make a dent on it, but that's still less than half the power of a hairdryer

 

I was wondering what one would need to route an oil pipe onto something which is through-bolted (with super heat conducting bolts) to a heatsink (maybe with small fan) on the inside of the firewall (on the basis that installing a standard oil cooler in the cabin would be totally forbidden with the oil pipes penetrating the firewall)

 

I find that with thick socks and pullover, something like -20 OAT with the heater full on makes it just about ok inside, when it gets down to -30 or -35 I need a thick jacket too, and after that then thick gloves, scarf, hat and the works.  It varies a bit depending on how much sun you can get in the windows

[Cris]

Have you checked to see if the winter plate used to cover the oil cooler is installed?

[Awful_Charlie]

Oil temperature isn't the problem, that'll be around 180-190F - it's the cabin temperature below freezing that is!

 

Such a shame there is so much heat just the other side of the firewall, only need a safe & legal way to get it to the inside

[Cris]

What I was thinking regarding keeping the oil temp up was that it might impact the EGT's. That exhaust gas temp is what is used to heat the air that is drawn around the muffler and then driven into the cabin. So if one could increase the EGT and still remain in an acceptable range the air should be heated to a higher temp for the heater. But maybe warmer oil has no bearing on the EGT's only mixture.

[Danb]

Great question I have a Gx and agree, I flew in my buddy's brand B today ad remarked to him how nice and warm his Bonanza was...I have a heated hanger so the problem is a deficient system, Chris may be onto something trying some other type of contraption? Put the baby's pix back up!

[jlunseth]

One issue is the location of the heater outlet, at the foot of the console, which does not help the footwells much.  Warm socks and footwear are really important even in the summer if we are going to the flight levels.  We have been known to tape the eyeball air outlets in the winter, because the butterfly plates always leak a little.  The real problem, I think, is that the cabin has a designed in air leak and it is probably not a good idea to block it.  There are vents just above the wing on both sides.  The biggest problem in my aircraft seems to be leakage through the tail and past the rear bulkhead, it is not sealed at all and we get a cold draft right on the back of the neck.  Not noticeable in the summer, but definitely noticeable at FL220 and -52 dF.  I have never found gloves necessary except for preflight and at the beginning of a flight, and a light jacket usually works for me even in cold temps as long as my feet are warm, but cold temps in the flight levels and in the lower altitudes are two different things.  The air packs a cooling wallop down low.  I just don't fly if it is -20 or more in the low altitudes unless I have to.

 

As I understand it, there is an adjustment in the heater system so it is possible to reduce the heat some.  You might have that checked to make sure your system is putting out full heat.  Also, if you are not aware of it, pulling the cabin vent control puts cold air into the heater flow so make sure the vent knob is fully closed.

[Nemesis]

I am not sure how the system on the M models work, but on my K model there are muffs wrapped around the exhaust headers right after each stack comes out of a cylinder. Oil and oil temp has nothing to do with it. Those headers 8" away from the cylinders have to be 1000 dF. With the owner assisted annuals that I have done, I have personally checked the muffs and associated scat tubing every year. Mine are all very tight with no or minimum leakage. My problem is that 10 minutes after I crack open the cabin heat with a little cabin vent for normalizing, I am just roasting; even when the OAT is -20 dC or lower. It is so hot that I have to keep a close eye on the defrost side to be sure that my windshield does not melt.

 

So, if the M setup is similar, I would first check the muffs and scat tubing under the cowl. Next, there is likely an opening on the pressure side (top side) of the engine baffles that feeds air into the heating system and muffs. I would check that opening and associated scat tubing for a clear air path and no pinched tubing. Then, I would check to make sure that the heat control is opening the air valve / butterfly in the heat box enough to allow for greater heat flow. Lastly, if the baffle seals are worn or are not sealing well against the cowl, there might be enough loss of air pressure so that the hole that feeds air into the heat system is simply not getting enough air. However, if that were the case, I would guess that you would have a cylinder temperature problem as well.

 

Dave

[Guest]

Thanks for the replies. Here is what we have attempted so far.

The problem seems to be that Mooney did not consider the environment in which a turbo charged aircraft would operate. The heater jacket area is quite small and is located on the forward cross over pipe well down stream of the left bank of cylinders. Heated air exits the heater then passes through a duct which is part of the inter cooler inlet NACA duct which is exposed to cold ambient air on the outer surface.

The other day we opened the jacket and wrapped the exhaust pipe with a 10 foot long coil spring in an effort to get more heat transfer. This is what Mooney did way back for the Mite. We've wrapped all of the scat ducts with fibreglass insulation, none of this seems to make much difference.

The owner does not report that the cabin is drafty, just cold. We may look at electric as the next option.

Clarence

[Awful_Charlie]

Some good ideas and observations coming along - keep them up!

The M heater has a muff on the crossover pipe, so only extracts heat from the odd cylinders. It takes air from just under the prop into the muff, which outlets into a dedicated void in the intercooler intake moulding, the inside of which has a heat shield to protect it from the collectors on the right hand side, and from the back of this via a bit of scat hose into the the heater mixing box (which as jlunseth points out, comes with the ability to mix in cold air) it then comes out from the bottom of the console.  On mine, the air comes out fairly hot, but move your hand back 6 inches or so and it barely feels warm: this makes we wonder if there is a restriction upstream somewhere, but of course upping the flow is likely to mean the temperature of it drops :-(

 

I've just bought myself a 'smoke stick' and intend to spend an hour or three in the cabin sometime, with a vacuum jury rigged onto the ceiling vents to see if I can find some significant leaks - the hint about the rear bulkhead will be a good starting point, but also intend to look around the floor, pedal boots, door seals to see where all the heat is going (or more likely, where there is cold coming in)

 

Up in the FL's I quite often get ice forming on the inside of the windows, ISA at FL250 is -35C, and when it is ISA-20 odd on the ground, the heater certainly has work to do.  Looking at the janitrol heaters used in twins, even the small ones are 20,000BTUs or more, which is like a 5kW heater - anyone care to guess what getting an approved fitment of one of those would be like?

[aviatoreb]

I figure my heater in my rocket is ok - I take off the heavy coat and gloves even at -35C oat but being at the bottom of the console, the heat output does not seem to reach the footwells - someone else mentioned that.  My feet get very cold on those especially cold days.  Very cold.

 

I fly with leather booties (no soles) in the winter and just socks in the summer - for pedal feel.

 

So I was just thinking about this topic on Thursday when it was -20C on the ground….and same up at 10k as it was a temperature inversion.  I am planning to try out these out - toe warmers - a cheap solution that will be good enough at least for the pilot(me):

http://www.amazon.com/HotHands-Toe-Warmers-40-pairs/dp/B0007ZF4PE/ref=sr_1_1?ie=UTF8&qid=1393764494&sr=8-1&keywords=hot+hands+feet+warmers

We use them anyway for cross country skiing when it is arctic conditions.

 

I was also thinking of getting some electric hunters socks.  The WWII bombers used to use electric socks and gloves.

 

Window frosting.  When it is -35C, window frosting is an issue.  Even at -20C on the ground, while I taxi I need to keep a door cracked and the side window open for the airflow if I have 3 on board to prevent windows from frosting on the insides.  Once flying only the rear windows are frosted.  If I am solo, I only keep the right side ceiling vent cracked while in taxi to prevent window frosting.

 

BTW at -30C my car does something funny - if I leave the windows closed after I drive then when I come back later all the moist air of my breathing has adhered to the windows and frosted ALL the windows from the inside, after shut off.  So to counteract that I need to remember to slightly crack on one window after I park it if it is in the <-30C range.  Sometimes I forget and I need to scrape the insides of my windows before I can drive.

[BorealOne]

Hey Clarence - 

 

I block the cabin inlet ducts that are just above the wing on each side of my Ovation with high density foam each fall, and remove it in the spring. That makes a huge difference to the overall cabin temps, especially in the footwells. My interior cabin temps in -30C OAT are around 10-15C - 'comfortable enough to fly without gloves and a toque', but certainly not 'by the fire toasty'. 

[carusoam]

What do you guys have for boots where the rudder pedals go through the floor?

My 65C had the original fabric boots. They were the source of cold air down low.

Carbon fiber would make nicer pedals to minimize the heat transfer / cooling effect on your feat. (Just an idea)

The pedals are attached directly to the outside temps, plus the boots are not air tight.

Best regards,

-a-

[orionflt]

To prevent heat loss or cooling  is to use double wall sceet or my product, not scat single wall duct.

 

I make silicone ducts with 2 ply fiberglass that are made in the correct i.d. x length with cuffs to slide on flanges etc.

( no wires to cut your hands or wear into something else )

 

I have copied all the beech cooling ducts and heater ducts, all of our product is smotth wall inside even during a 90 degree bend the wall stays smooth..

this provides more cooling/more heating.

 

want pics

 

N77GB@NSN.COM

GB

yes please