Outside Air Temperature gauge?

[IvanK]

So does the BS atmospheric model actually model temp reduction with altitude ?

(I assume it does)

[AlphaOneSix]

So does the BS atmospheric model actually model temp reduction with altitude ?

(I assume it does)

 

Yes, it does.

[bogusheadbox]

Here, we often fly at temperatures well below -15°C on aircraft that are not equipped with deicing equipment. Avoiding icing conditions is crucial and the temperature is really not a good indicator.

 

 

The thing to note with icing is that it is dependant on air pressure, moisture content and temperature. The less pressure air has and the colder it becomes, the less moisture it can contain. Physical airframe icing will be most prevalent in low temperatures above and below zero with high moisture content. so it goes to reason (in theory) that the colder the air is and the higher you fly the less moisture it can hold and the less likely you will encounter icing.

 

Though remember air is a collection of parcels of air of different temperature / density spanning in volume of space and moving in 3 dimensions. So you can have a cold air parcel moving through warm air or vice versa (clouds and fronts)

 

The most prevalent form of icing actually happens in moist warm air and is known as induction or carb icing described below.

 

 

mmm yes, Developer comment might be good on this, I fly a 172S Regularly here in Colorado, things to Note about Icing

 

it Requires Visible Moisture - Ie... a Cloud, Rain, Sleet, or Snow

the temperature that Icing becomes a big factor is a bit below 0*, and the reason for this - the faster it's moving, the more friction, more friction more heat, Airplanes do their own De-icing work to a *Small* extent :pilotfly:. by that standard, why do my engines die when flying over the mountains in partly cloudy weather? - when avoiding clouds, the aircraft should have No need what-so-ever for Anti Icing in temperatures well below Zero. a Cloud at that altitude is something to worry about though :noexpression:

 

Moist air well above zero is a major factor of induction or carburettor icing. And is the one of the largest contributing factor to forced landings. Induction / carb icing can happen in tempereatures as high as 15 degrees celsius or slightly higher depending on air conditions (high moisture content)

 

Carb icing is most prevalent and this is caused by the venturi effect from the air appature controlling the flow of air into the carb to be mixed with fuel. From Bernoulli's law, the venturi effect will cause a pressure drop of the flow of air. As the pressure drops it cannot sustain as much water and will become more saturated. The air speed increases and cools the water vapour to a point where ice forms in the throat of the carburettor causing a restriction of air. This will result in power loss and possibly engine failure.

 

This is why carburettor engines on low revs will be prone to icing more than an engine at high revs and can suffer from icing at temperatures well above 0. At low revs the butterfly or appature introducing air to the carburettor will be mostly closed. It is here that the venturi effect will be greatest (and from bernoulli's law) the pressure drop the greatest leading to a greater chance of icing.

 

Fuel injected engines won't suffer from carb icing but are still succetpable to induction icing.

 

At full power the butterfly or appature in the carburettor will be fully open with very little venturi effect.

 

Hence why a lot of carb craft suffer from icing on decent causing engine failure.

 

Induction icing works fairly similar in principle from the venturi effect of the air intake restriciton / air speed increase feeding the engine.

 

 

So in real life.

Icing can happen at temperatures well above 0 degrees c.

Lowering the air pressure, the less water can be contained in the air.

Lowering the temperature, the less water can be contined in the air.

 

Its a combination of these factors that can cause icing and the reason why an OAT is a good indicator and here is the reason why.

 

Before take off you grab the met weather. This will give you an idea cloud base, temperature and dew point.

 

As we know as pilots that we are passing through parcels of different air, its stands as prudent that a drop in OAT whilst in flight in what we deem to be possible icing conditions will warn us that icing will become more likely.

 

An OAT is not a device that will tell you exactly when you will encounter icing. It is however a great indicator that your likelyhood of encountering icing is increasing. A very useful device.

 

Anyhow i have rambled.

Edited January 15, 2009 by bogusheadbox

[IvanK]

Yes, it does.

 

Good ... then we need a working OAT gauge :)

[miguez]

Several aircraft have ice detection systems, and some of those, like the Embraer 145 and 170 family, have the anti-icing system kick on automatically when icing is detected.

 

In the Ka-50 we have an ice detection system, although it appears not to be functioning. i am talking about the Ice Detected light on the Auxiliary Panel. The EKRAN warning, as far as I know (can someone confirm/disprove this?), is based solely on OAT.

[manbird]

Good ... then we need a working OAT gauge :)

 

being a RL pilot, I see things a bit differently. The only times I ever use an OAT is when calculating my True Airspeed. All Icing detection and avoidance is done by visual means, or by routing my flight to avoid areas of expected icing conditions.

 

In particular, 747 and 767 pilots don't use OAT for anti Icing at all. Simply they are told to use it in visible icing conditions. It takes more than low temperature to create icing conditions.

 

The decrease in OAT at altitude is a standard formula, and the only reason the fomula is used is to, again, calculate your True Airspeed.

But this isn't necesary for glass cockpit aircraft like the KA-50.

 

So, no, you don't need an OAT gauge, which is probably why it was left out.

[manbird]

Secondly, don't confuse de-icing with anti-icing. The KA-50 does NOT have de-icing ability for anything other than the canopy and the windscreen (which is a liquid agent sprayed onto the surface). It has ANTI-Icing equipment.

 

Anti Icing equipment, like on most aircraft, is turned on, to prevent icing in case of icing conditions. Therefore a good policy to turn it on at high altitudes and in visible icing conditions. Which is what we do in this sim. regardless of what the OAT gauge says. The OAT guage is not an icing detection guage.

 

DE-Icing equipment, like on large aircraft and some smaller aircraft, use bleed air or deicing boots to get rid of icing that is FORMING on the surfaces, and is only used when icing is seen forming on the plane. And it is periodicaly used in icing conditions, in conjunction with anti icing equipment, to break up forming ice.

 

In this simulator, we are told to turn on ANTI-icing equipment to prevent icing forming in our engine, or on our rotors. It just so happens (IMHO) that to simplify the weather engine in DCS, they gurantee that you will get icing if you fail to turn them on.

 

Since it's policy to turn them on at high altitudes and low temperatures (JUST IN CASE), why go through the bother of simualting icing regions? So you can purposly fly into a cloud and roll the dice to see if your engine will go Kapuut?

 

-manbird out

[AlphaOneSix]

I look at the OAT all the time in when I fly! But mostly just so I can see why I'm freezing my rear end off (we fly at night at altitudes exceeding 11k with the doors open*...brrrr).

 

*Actually, at 11k we usually have the doors closed, it depends on how high above the ground we are. In some places, we have the doors open at about 9k AGL, at about -18C outside. Talk about wind chill!

[manbird]

hehe, the only time I ever touch the OAT guage, is when I have to rotate it to let in some outside air, since it's usually attached to the outside vent. Damn magnifying canopy glass!!

[manbird]

If you want to know when to turn on ANTI-Icing, do what evey other pilot does, take the temperature you set in the mission editor or from the flight briefing, if it's under 5c then turn it on.

 

Then take the same temp, and reduce it 6.5c for every 1000 meters, if you get to under 5c then turn it on.

 

So for example, if your airfield temp is 25c, then you would effectively turn on Anti-Icing at around 3,800 meters. ROUGHLY, simplified for this sim is..

Your OAT is (Ground temp - (6.5*(current alt/1000)))

[Aser]

 

So, no, you don't need an OAT gauge, which is probably why it was left out.

 

As CPL/IR helicopter pilot with experience in IFR and some icing in the helo, don't tell me I don't need a OAT gauge.

It's ok if ED don't want to make it but you don't come here and teach us if we need it or not, just point me one aircraft without OAT or just a f*** compass!

 

 

Regards

Aser

[manbird]

As CPL/IR helicopter pilot with experience in IFR and some icing in the helo, don't tell me I don't need a OAT gauge.

It's ok if ED don't want to make it but you don't come here and teach us if we need it or not, just point me one aircraft without OAT or just a f*** compass!

 

 

Regards

Aser

 

Aser, no need to be rude. Be thankfull you have a compass. ;)

 

BTW, Since we're flashing badges, I'm a PPMSEL/ IFR myself in airplanes.

Edited January 16, 2009 by manbird

[manbird]

IN all seriousness, if you want an OAT gauge that is useful in this sim, then they'll need to add various temperature regions and atmospheric moisture regions, since temperature is not an indication of icing alone. Otherwise, all you have is a boring instrument that does the same thing every time, which is go down at altitude, and stay the same at ground level, no matter where you are. Really neat.

[IvanK]

Manbird

 

"Real pilots" specfically use OAT and TAT and visible moisture as criteria to switch Anti ice on ... Certainly on the B767,B744,A330, and A380 :)

Edited January 16, 2009 by IvanK

[Draco]

I look at the OAT gauge everytime I fly to determine available power and probability of carb ice.

[manbird]

Manbird

 

"Real pilots" specfically use OAT and TAT and visible moisture as criteria to switch Anti ice on ... Certainly on the B767,B744,A330, and A380 :)

 

 

I meant to say they don't use it exclusively.

[manbird]

I look at the OAT gauge everytime I fly to determine available power and probability of carb ice.

 

 

Same here. But I'm talking about the Sim. If we are talking about real life, then yes, OAT would be VERY helpfull.

[manbird]

Oh what the heck, throw in the OAT in the upcoming patch. I was trying to communicate that OAT is really not that important in this sim since BS doesn't model moisture content and varying temperatures and inversion layers. Whatever makes ya' happy. I say go for it!

 

Perhaps I failed to communicate that OAT is not the only indicator of icing conditions and that the other variables are not simulated in BS, therefore no need for an OAT gauge.

 

If you feel that there is, great. But I don't. For those of you who felt I was "teaching", my apologies. I truly have no place here on this board.

 

Cheers and enjoy what DCS has given us, and we welcome any improvments.

 

-Manbird over and out. :pilotfly:

[PE_Tigar]

I guess it's all different between helos, large turbine airplanes and small GA, but I'm flying (GA airplanes) a lot in marginal VFR with a lot of haze and low clouds in wintertime and let me tell you, I am very much paying attention to the OAT gauge.

 

That said, though, what would really help would be an explanation of how the EKRAN knows when to tell you to turn the de-ice on. If it's just interpreting the OAT input then we don't need the OAT gauge. If there is a separate ice detection system then again, we don't necessarily need it - it feeds into the EKRAN. This is in the sim. In real life, I wouldn't fly combat missions in icing conditions without an OAT gauge operational - even if it's "just" a backup.

 

Of what kind that ice detection system would be, I wouldn't know, I'm in ATPL training now and never heard of such a system, but we're mostly focused on B737 Classic and A320 family for systems, and they have pretty rudimentary ice detection equipment. A320 has basically a small rod with a light shining on it, visible from the cockpit. Funny thing is that the light is in MMEL and you can't fly with it inop :).

[DiabloSP]

I wouldn't fly in comfort waiting for the Ekran to tell me that I need to turn on the anti-ice equipment. I have lost both engines almost at the same time, twice, and Ekran said nothing at all prior to that.

 

As most people said before, turning anti-ice is a must under certain conditions. I guess, and that's just a guess, that if the icing is too fast, or if the "ice sensor" is already iced before takeoff, the Ekran shows nothing at all.

[PE_Tigar]

Well, since those certain conditions include mist/fog/precipitation and OAT below a couple of degree C (common in the Caucasus), and you say that EKRAN can't be relied upon 100%, we do need OAT indication then.

[ViperTech]

Me don't need a OAT at the sim, I just turn on de-icing at above 3k and/or temperature below 10°C.

For all the other who need OAT...just work out a little LUA-script that calc the temp and throw it to your sight through chatlines or other output. Shouldn't be so hard to code that or? Maybe you can code an automatic turning on of the de-icing-systems at the known conditions. :smilewink: