ICED TRIKE WINGS

[Asterix]

I post this new thread, having posted a "caveat" in the section dealing with destinations, under the Elands River Quad Camp thread, having reflected on the ice I encountered on my wing and my decision not to take of on a planned flight.

Pilots who do fly aways in winter will often find themselves securing their trikes at their destination at sundown before the onset of bright windless winter nights. Temps will drop to below freezing overnight with no wind, and they will find themselves confronted next morning in pre-dawn as they approach their trikes, shining their torches over their wings, with a diamond - like reflection of millions of pretty little ice crystals. Nothing looks out of place, except for the glitter.

As someone who dropped out of physics and maths at around 16, I would like to pose the following questions/ideas , and ask the more clued up guys to correct, or add comment. Please don't laugh.

Here goes: My wing flies because of pressure differential. Air slows down on the underside of my wing, thus creating a high pressure, producing lift. If the air slows on top of the wing, it might equal the reduced pressure on the underside of my wing, thus creating a neutral situation.

In order for the pressure to drop on top, the airflow must be faster, unhindered, and laminar. If not, no pressure differential will result, and no lift will occur.

The top of my Aquilla 2 wing has been designed to make air flow faster, and the bottom to "heap" up the air.

If I have "stuff", like little ice crystals, on the top, then the laminar airflow will be disrupted and millions of microscopic "windshears" will occur, resulting in the top airflow slowing down to the point where there is no or too little pressure differential. Thus no take - off.

If one wing is "clean", and flies normally, and the other wing is full of this little crystals, the former will start flying quicker, and the latter will lag for a second or two, resulting in a very steep "dip" on the latter, iced up wing, and it will stall dramatically because of the airspeed which is barely above the aircrafts stall speed. One wing flies, the other is almost flying - but not yet.

Am I being paranoid, or is wing icing on a trike a real danger? I have been branded as over cautious on occation because of this, but I feel that I am right?

[Africa]

In the winter when setting my trike outside I will swwp the top of the wing with a brush or a broom before take off. This is a very valid and comon danger in the cold as ice definatly affects your lift and the way the wing flies. you can use any brush or even a rag or a dirty shirt to wipe the wing top surface down before take off.

[Newguy]

First off. Forget the rubbish you learnt to pass your exam...that the pressure differential is what causes the wing to fly etc.. The wing fly's because of the lift from deflecting the air down. The second cause is Coanda effect which explained is water clings to the back of a spoon. This deflects the water which is an action. Newtons reaction is it moves in the opposite direction. Read Jim Davis What makes it Fly p20. FORGET THE PRESSURE DIFFERENTIAL. A cessena 152 would have to go supersonic to generate enough lift for take off!! Again not my words but Jim Davis and those of NASA (www.lerc.nasa.gov/WWW/K-12/airplane/wrong1). Regards icing i'm sure it has a negative effect but not for the reasons you have outlined. I'm sure those with more knowledge will help out here. Read what actually makes a plane fly its probably what you always believed in the back of your mind .

[Biggles]

If you are refering to a thin coating of frost on a wing it will slightly increase the parasitic drag. Air right against the skin experiences x drag. Then the drag felt as you move away from the skin will rapidly decrease. So you will have a very thin layer of air moving slower than a clean wing but it will be minor. You will even get people that argue that a ruff surface will have less drag. (think of a golf ball) but the effect will be minor. This parasitic drag will be overcome by thrust and the ovall airflow over the wing will remain the same.

The danger from icing is when it changes the shape of the airfoil. This would require large slabs of over a cm thick ice.

[Mc Guyver]

Many years ago I was at the Aerotrike factory in Springs when an almost brand new 912 (one of the first) arrived on a trailer in a very sorry state.
He had parked overnight at an airfield, frost on the wing and he ran out of runway when trying too take off and ended up in a ditch as he could not get lift.
So I would say with frost on the wing don't take a chance

[Biggles]

Many years ago I was at the Aerotrike factory in Springs when an almost brand new 912 (one of the first) arrived on a trailer in a very sorry state.
He had parked overnight at an airfield, frost on the wing and he ran out of runway when trying too take off and ended up in a ditch as he could not get lift.
So I would say with frost on the wing don't take a chance

Iesh did not think it would have that big an effect!!! Better get that dust off the top of my wing ASAP!!

[Africa]

agree with Mcguyver I too have seen a few trikes loosing lift from frost and ditching. wipe it off, its not worth it

[JCH]

I know of one incident where Frost played a role in an accident.

This guy also seems to think that one of the causes of trike accidents can be attributed to heavy dew or frost.
Written in 2004 - possibly still valid.

http://www.upac.ca/trikers_corner/Trike ... l-2004.pdf

[AlanM]

I posted this in 2008 under the heading "I learned from that".........

Ice on the Wings


I recall during my training how our instructor Peet at Crosswinds used to not allow us to take the trikes out of the hangar in the early winter pre dawn mornings to avoid dew forming on the wings.
The dew might turn to ice. Even if the wings were wet in any way, he would not fly until they were dried off.

I was to learn very clearly what he meant on a trip to Dragon Peaks in the Drakensberg in July 2002 – mid winter.

The hangar space that was promised to us on booking our accommodation did not materialize, and I had to leave the aerie out in the open overnight.

The following morning at dawn, during the pre-flight inspection, I noticed a very thin layer of ice on the upper wing surface, which I brushed off as best I could with a cloth. The ice came off fairly easily, leaving the wing wet, with ice only in the centre of the wing, where I couldn’t reach.

I strapped my passenger in, warmed the motor, did my pre-take off checks, and pushed full throttle for take off.

The first thing I noticed was that the take off roll was taking longer than the previous afternoon’s flight. I carried on, checked airspeed, and pushed the bar full forward for rotation. All the aerie did was lift the nose wheel off the ground, and as soon as I pulled the bar in, the nose wheel came down again. I tried once more as I now had more than enough airspeed – same thing, so I aborted, cut the throttle, and applied brakes, only now to find that the grass is also frozen, and we are skating along merrily towards the end of the runway. Fortunately we came to a stop with inches to spare.

We waited for the sun to melt the ice, wiped the wing completely dry, and took off normally an hour later for a most enjoyable flight.

Lessons learned:

- DON’T take off if there is any sign of icing. Even moisture will re – freeze in winter on the take off roll.
- I was fortunate in a way, because if the icing had been less severe, I would have got airborne, and then found that I had limited climb performance, and who knows what would have happened then.
- Winter flying has its magical moments, but it also has its hidden dangers.

[Morph]

Icing on the wing surfaces even downs beeg aeries. What makes you think a trike is impervious to this.

[Biggles]

Frost and icing are different things.

Frost is when water vapour directly freezes onto a surface. Create a fine fur of crystals. This creates drag. And can be overcome by thrust. Not good but not as bad as...

Icing is when water freezes on a surface. Such as dew or rain. This deforms the aerofoil and destroys the ability of a wing to create lift.

[Africa]

Frost and icing are different things.

Frost is when water vapour directly freezes onto a surface. Create a fine fur of crystals. This creates drag. And can be overcome by thrust. Not good but not as bad as...

Icing is when water freezes on a surface. Such as dew or rain. This deforms the aerofoil and destroys the ability of a wing to create lift.

I dissagree, frost is infact dew that freezes to the wing and you can loose lift severely and it can mess up your aerofoil completely. Iceing is when you are flying and ice builds on your leading edge due to freezing moist conditions, flying in fog/mist in below freazing conditions. You cannot get icing on a clear sunny day no matter what the temp and what the atlitude. but frost can ocur on anyday with subzero temps as long as there us due on your wing. i have seen frost cause a sheet of ice on a trike wing and if the opilot had atempted take off he would have had a big repair bill

[Gyronaut]

Never underestimate the effect of smoothe air over an airfoil.

I have experienced serious rotor shake in a gyro simply because the 3ft sock on one end kept the dust off, the rest of the rotor had a thin layer of dust on it. Landed, cleaned the rotors and flew smoothly after that!
Of course Ice/Frost of any kind will affect the performance of the wing negatively just like a dirty prop will affect your machines performance negatively.

[Asterix]

I am feeling a bit of vindication - I am NOT over-cautious. "New Guy" - any comments on your alternative theory?

[Biggles]

Frost and icing are different things.

Frost is when water vapour directly freezes onto a surface. Create a fine fur of crystals. This creates drag. And can be overcome by thrust. Not good but not as bad as...

Icing is when water freezes on a surface. Such as dew or rain. This deforms the aerofoil and destroys the ability of a wing to create lift.

I dissagree, frost is infact dew that freezes to the wing and you can loose lift severely and it can mess up your aerofoil completely. Iceing is when you are flying and ice builds on your leading edge due to freezing moist conditions, flying in fog/mist in below freazing conditions. You cannot get icing on a clear sunny day no matter what the temp and what the atlitude. but frost can ocur on anyday with subzero temps as long as there us due on your wing. i have seen frost cause a sheet of ice on a trike wing and if the opilot had atempted take off he would have had a big repair bill

Firstly I am not saying iether one is not dangerous. Just the effects of frost and icing are different. Frost creates drag, icing deforms the aerofoil.

Frost occurs when the surface temprature drops below a subzero dew piont temprature. So no liquid dew forms and water vapour condenses directly to solid. Making hair like ice crystals.
wiki definition:

Frost is the solid deposition of water vapor from saturated air. It is formed when solid surfaces are cooled to below the dew point of the adjacent air as well as below the freezing point of water.[1] Frost crystals' size differ depending on time and water vapor available.

While I suppose sufficient frost could cause deformation of the airofoil it would be a spectacular amount of frost.

Icing is when liquid on a wing freezes. This will be any liquid like dew, rain or even snow. This is why what affects the big metal is called wing icing. Not frosting.