Might be a dumb question, do cessna's have a defrost for the windshield? I rent 152's and 172's and have wondered what to do if im flying along and the windshield begins to fog up? Is there a defrost similar to a car, if so how do you use it?
C152/172 windshield defrost?
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dlsmith
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Dylan Smith
The cabin heaters will normally blow some hot air on the windshield to defrost it, like in a car. You can't control the defrost independently from the rest of the heating system though. It's either all on or all off.
MAKG1
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If it's fogged, not frosted, you can often direct the vents, in addition to or instead of cabin heat. Or open the windows.
It's not too unusual to fog up windows during preflight at night, if the temperature drops a lot. Since I don't fly at night with a really low dewpoint spread, engine start and an open window has always cleared it right up.
It's not too unusual to fog up windows during preflight at night, if the temperature drops a lot. Since I don't fly at night with a really low dewpoint spread, engine start and an open window has always cleared it right up.
DavidWhite
Final Approach
I second opening the window, it helps quite a bit to de-fog the airplane.
Stewartb
Final Approach
Once the cabin heat is stabile at a normal cabin temp it's highly unlikely you'll have any moisture appear on the interior side of the windscreen. Most windscreen fog comes on a cool day when your warm body brings humidity inside a cold cockpit. Most Cessnas have a cabin heat control that you can control by how far you pull it out. It is not all or nothing. On top of that most defog vents have some adjustment to restrict or direct windscreen air flow.
oldShar
Cleared for Takeoff
The avionics cooling fan also helps to (eventually) defog the windscreen, starting from the center bottom and working upward and to each side
Pedals2Paddles
Cleared for Takeoff
On a related note, let me explain to you how the heat in general works. Think VW Bug.
When you pull the heat lever, air flows through the exhaust shroud and into the cabin. The hot metal exhaust heats the fresh air passing over it. There is no blower fan like your car. It is just ram air into the cowling. That air is ducted in down by your feet and up on the windscreen. Therefore:
1. You get no heat until the exhaust is warmed up.
2. You get very little if any air movement while parked
3. You get ok air movement while taxiing.
4. You get lots of air and lots of heat once you're underway.
5. If your exhaust leaks, you will ave a CO poisoning issue.
On the ground, it can be cold and frustrating due to the low heat and low air volume. As others have said, use the windows and doors to keep the humidity down. Every time you exhale, you're pumping humidity into the cabin. Just like during the summer. But instead of it being hot and humid, it is cold and humid.
In flight, there are sometimes only two functional settings, no matter how much you try to adjust the little lever. Those two settings are "off" and "flame kissed". The heated air will be very very heated. You will probably need to mix in the cabin air vents and the wing root vents to keep it from getting too hot.
When you pull the heat lever, air flows through the exhaust shroud and into the cabin. The hot metal exhaust heats the fresh air passing over it. There is no blower fan like your car. It is just ram air into the cowling. That air is ducted in down by your feet and up on the windscreen. Therefore:
1. You get no heat until the exhaust is warmed up.
2. You get very little if any air movement while parked
3. You get ok air movement while taxiing.
4. You get lots of air and lots of heat once you're underway.
5. If your exhaust leaks, you will ave a CO poisoning issue.
On the ground, it can be cold and frustrating due to the low heat and low air volume. As others have said, use the windows and doors to keep the humidity down. Every time you exhale, you're pumping humidity into the cabin. Just like during the summer. But instead of it being hot and humid, it is cold and humid.
In flight, there are sometimes only two functional settings, no matter how much you try to adjust the little lever. Those two settings are "off" and "flame kissed". The heated air will be very very heated. You will probably need to mix in the cabin air vents and the wing root vents to keep it from getting too hot.
Pedals2Paddles
Cleared for Takeoff
Just make sure it won't overload the lighter plug. Most of them I've noticed are fused or CB'd at 10 amps. Traditional automotive light plugs are 15-20 amps. So if you buy a 12v hair dryer designed for a 15-20 amp outlet, it will not be much use in a plane with a 10 amp limit.
MAKG1
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I'd be very concerned about warping the plexiglass. It doesn't take much. Just open the window.
ARFlyer
En-Route
I like the set up on the newer Piper Arrows. There are two levers that work the heat and defrost independently. So you can mix and match depending on how much and where you want the heat.