Farsight
Topic Author
Posts: 26
Joined: Wed Feb 27, 2019 8:20 pm

Runway Aquaplaning

Wed Apr 17, 2019 7:40 pm

Hi All

What stops planes from aquaplaning in wet conditions? I know that the rudder can minimise this above a certain speed and add stability, but I am surprised it doesn't seem to happen more often. Aircraft tires seem remarkably simple (in comparison to automotive tires). Am i missing something?
 
thepinkmachine
Posts: 368
Joined: Tue Apr 28, 2015 4:43 pm

Re: Runway Aquaplaning

Wed Apr 17, 2019 8:01 pm

Perhaps higher tire pressure prevents aqua planning?
"Tell my wife I am trawling Atlantis - and I still have my hands on the wheel…"
 
VSMUT
Posts: 3012
Joined: Mon Aug 08, 2016 11:40 am

Re: Runway Aquaplaning

Wed Apr 17, 2019 8:19 pm

It happens more often than you think. It is best prevented by doing a firm touchdown and using the wheel brakes carefully.
 
e38
Posts: 627
Joined: Sun May 04, 2008 10:09 pm

Re: Runway Aquaplaning

Wed Apr 17, 2019 8:56 pm

Farsight, the situation you are referring to is more commonly called "hydroplaning" in the world of aviation, not aquaplaning.

With regard to your question, "Am i missing something?" Well, yes. Most of my flying is done in the United States and at many large commercial airports, some, if not all, of the runways are grooved. This allows water to be channeled off the actual surface of the runway. I don't know if airports outside of the U.S. have grooved runways as well--other A.net members will follow this response with additional information on airports outside of the United States.

The grooved runways are effective to the point that for some aircraft and/or operators, there may have provisions in the aircraft performance manuals such that even if it is raining, a grooved runway may be considered "dry" for landing and/or rejected takeoff operations.

Of course, even with a grooved runway you have to use some judgment and common sense. It is important to remember that the touchdown zone of the runway (first/last 3,000 feet depending which way you are looking)--the portion with a lot of rubber deposits from landing aircraft--can deteriorate to the point of being considered "icy" when it is actually just wet.

So, grooved runways help reduce the propensity of an aircraft to hydroplane, but they do not eliminate it.

Lot of variables.

e38

starlionblue, you're up . . .
 
CosmicCruiser
Posts: 2342
Joined: Tue Feb 22, 2005 3:01 am

Re: Runway Aquaplaning

Wed Apr 17, 2019 10:32 pm

thepinkmachine wrote:
Perhaps higher tire pressure prevents aqua planning?


I was always taught the the speed at which you will hydroplane is 9 x the square root of the tire pressure so higher the tire pressure higher the hydroplane speed.
 
Max Q
Posts: 7697
Joined: Wed May 09, 2001 12:40 pm

Re: Runway Aquaplaning

Thu Apr 18, 2019 2:35 am

e38 wrote:
Farsight, the situation you are referring to is more commonly called "hydroplaning" in the world of aviation, not aquaplaning.

With regard to your question, "Am i missing something?" Well, yes. Most of my flying is done in the United States and at many large commercial airports, some, if not all, of the runways are grooved. This allows water to be channeled off the actual surface of the runway. I don't know if airports outside of the U.S. have grooved runways as well--other A.net members will follow this response with additional information on airports outside of the United States.

The grooved runways are effective to the point that for some aircraft and/or operators, there may have provisions in the aircraft performance manuals such that even if it is raining, a grooved runway may be considered "dry" for landing and/or rejected takeoff operations.

Of course, even with a grooved runway you have to use some judgment and common sense. It is important to remember that the touchdown zone of the runway (first/last 3,000 feet depending which way you are looking)--the portion with a lot of rubber deposits from landing aircraft--can deteriorate to the point of being considered "icy" when it is actually just wet.

So, grooved runways help reduce the propensity of an aircraft to hydroplane, but they do not eliminate it.

Lot of variables.

e38

starlionblue, you're up . . .



Grooving is important and helps in water
drainage but just as critical is that the runway be crowned

Otherwise it will not run off and you’ll have a standing water situation
The best contribution to safety is a competent Pilot.


Guns and the love of them by a loud minority are a malignant and deadly cancer inflicted on American society
 
LH707330
Posts: 2210
Joined: Fri Jun 15, 2012 11:27 pm

Re: Runway Aquaplaning

Thu Apr 18, 2019 6:02 pm

"Aquaplaning" is a common term in Germany and some other places, typically referred to as "hydroplaning" in the US. Different strokes....

Regarding why plane tires (and bike tires) don't hydroplane as much as car tires is the much higher ground pressure of the contact patch, and its ability to push water out of the way. Plane tires typically have the circumferential grooves to allow water out between them, with the treads themselves being good at pushing the water laterally. Regarding the shape, plane and bike tires have a longitudinal oval contact patch, whereas car tires have a more rectangular patch that's typically wider than it is long. This is because bike and plane tires' main traction requirement is braking, the cornering requirements are much smaller. Car tires, meanwhile, have to corner better, hence their differently shaped contact patch that results in more hydroplaning as a tradeoff.
 
Farsight
Topic Author
Posts: 26
Joined: Wed Feb 27, 2019 8:20 pm

Re: Runway Aquaplaning

Thu Apr 18, 2019 7:23 pm

Interesting, thank you for the replies!

So aquaplaning/hydroplaning DOES happen occasionally. It seems like if an aircraft were to start sliding to one side I can't imagine the nosewheel steering having enough authority to correct.

I've searched youtube hoping for some examples but haven't found any proper sideways action, and despite grooved runways I have found videos that show aircraft running down the runway through substantial puddles.
 
Farsight
Topic Author
Posts: 26
Joined: Wed Feb 27, 2019 8:20 pm

Re: Runway Aquaplaning

Thu Apr 18, 2019 7:25 pm

I suppose the general geometry of aircraft landing gear (2 mains, 1 nose) adds inherent stability kind of like a rail dragster with the big wide rears and skinny front tires too.
 
LH707330
Posts: 2210
Joined: Fri Jun 15, 2012 11:27 pm

Re: Runway Aquaplaning

Fri Apr 19, 2019 7:54 pm

The TAM3054 and LH2904 crashes involved hydroplaning, I'm sure there were others as well.

Regarding the nosewheel, they only have a small percentage of total weight on them, so not much authority. Depending on the airspeed, the rudder would likely do more. I don't know how sophisticated the ABS system logic on a given design is, so I don't know how they deal with skids. One consideration I would have as a designer is what to do if one leg hydroplanes and the other is still on dry ground, how much yaw should one allow before modulating the brakes on the good leg to prevent the plane going sideways, and is that a worse failure mode than going straight...? Lots of stuff to think through there.

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