If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
air humidity
It's not humidity, per se, but visible moisture that's the risk
factor. You don't need a gague to detect that. "karel adams" wrote in message ... depending on where one flies, icing is a major concern the risk of icing depends on outside air temperature and humidity but this puzzles me: it is quite normal for an aircraft to have an ourside air termometer but i never heard of an outside air hygrometer gauge i am wrong once again or is there a good explanation? grateful for all your patience, karel |
#2
|
|||
|
|||
This depends on whether he was talking about airframe icing or carb icing,
and that isn't at all clear from the original post. Carb ice is quite possible without visible moisture, but it isn't a major risk, if the pilot is alert for signs of slow, progressive power loss, the aircraft has an effective carb heat system, and the pilot uses it properly. Airframe ice is quite often not seen even if you are flying in visible moisture, i.e. in a cloud or in precipitation. But there are so many variables at play that it is not really practical to nail it down to a simple, single number that says whether you will collect ice or not. You would need to have instruments to determine at least two numbers - mean droplet diameter and liquid water content. But even that doesn't tell the whole story as the spectrum of droplet diameters may vary quite a bit, so the single measurement of mean droplet diameter doesn't give the whole story. Once you had all this real-time data, you would need to spend a whole bunch of mental energy putting it together with the ambient temperature and total air temperature to figure out whether you were in the icing envelope or not. And to make it all much worse the icing envelope will vary with type of aircraft, as some aircraft are more efficient collectors of ice than other types. It is easier to just look out the window and see if you are collecting ice. Kevin Horton RV-8 (finishing kit) Ottawa, Canada http://go.phpwebhosting.com/~khorton/rv8/ e-mail: khorton02(_at_)rogers(_dot_)com On Sat, 17 Jan 2004 22:22:40 -0800, Corrie wrote: It's not humidity, per se, but visible moisture that's the risk factor. You don't need a gague to detect that. "karel adams" wrote in message ... depending on where one flies, icing is a major concern the risk of icing depends on outside air temperature and humidity but this puzzles me: it is quite normal for an aircraft to have an ourside air termometer but i never heard of an outside air hygrometer gauge i am wrong once again or is there a good explanation? grateful for all your patience, karel |
#3
|
|||
|
|||
On Sat, 17 Jan 2004 21:21:48 -0000, "karel adams"
wrote: depending on where one flies, icing is a major concern the risk of icing depends on outside air temperature and humidity but this puzzles me: it is quite normal for an aircraft to have an ourside air termometer but i never heard of an outside air hygrometer gauge there is no such thing as an outside air hygrometer. the instrument is called a psychrometer and it basically is a fan forcing air over two thermometers. one is surrounded by a wet wick, the other is just bare dry glass. evaporation cools the wet thermometer. when you set it in motion and the temperatures stabilise you read the two temperatures. precalculated tables are used to derive the humidity. on an aircraft icing is to be expected occasionally and that is what the carby heat is for. it directs hot air from an exhaust muff into the carby to melt away the ice. works well on my aircraft. Stealth Pilot Australia |
Thread Tools | |
Display Modes | |
|
|