Clay Pans - Landing on Damp Ones.

[walrus]

As some may know, it’s been raining in the outback.

 

Dry clay pans I have experience- all good.

 

Damp clay pans, not so much. Does anyone have experience they wish to share? My inclination is to avoid one. Yes, I am seeking local knowledge but at present it’s not yet available. A precautionary search is a possibility but I’m not sure is going to  show much.

[APenNameAndThatA]

I'm pretty sure it would be a disaster. The main reason that I bought an aircraft and learnt to fly was to land on clay pans, but I have never done it. I imagine that a 4WD running 14 PSI (a low, sand pressure) would sink, so an aircraft running the same pressures would sink and flip over. Being clay, if you did not sink, you would probably pick up a lot of very sticky mud and the stickiness would stop you gaining enough speed to take off. What I most fear is landing in an apparently-dry clay pan and breaking through the crust. You might be able to check the condition of the surface by flaring, going along with your back wheels on clay pan, taking off again, and thinking about it. Disclaimer: no knowledge of that of which I speak. 

 

What is your technique? I would *really* love to know. 

[RossK]

Hmmm

Stuck in Salt Lake Clay

[walrus]

Yes Ross, I’m aware of salt lakes and the breakable crust. This is different- it’s a hard surface clay pan that has been used as a strip for generations - but I don’t know what it might be like if damp.

[KRviator]

51 minutes ago, RossK said:

Hmmm

Stuck in Salt Lake Clay

Yep, I was going to link to that one too.

[FlyBoy1960]

an old flying school instructor once told me if you are going to land on clay pans or on beaches to take a decent sized rock with you about the size of a tennis ball. fly over your intended landing area and throw the rock out the window. If it skips several times then you are safe to land, if it disappears, you will to !

[APenNameAndThatA]

A clay pan and a salt lake are different things. 

Edited April 26, 2022 by APenNameAndThatA

[onetrack]

As with all Outback conditions, if it has been raining within the last 10 days, you need to keep right out salt lakes, claypans, and most red soils - even if they look hard.

Rain softens claypans, and even though you may not bog in them, there will be a layer of sticky red clay on some, which can causes problems with anything with wheels on it, that tries to operate on it.

[pmccarthy]

Happens with black soil in river flats too. 

[turboplanner]

2 hours ago, onetrack said:

As with all Outback conditions, if it has been raining within the last 10 days, you need to keep right out salt lakes, claypans, and most red soils - even if they look hard.

Rain softens claypans, and even though you may not bog in them, there will be a layer of sticky red clay on some, which can causes problems with anything with wheels on it, that tries to operate on it.

In addition, during the time the clay pan is inundated, winds can move the topography around and create ridges, and floating tree branches can be pushed around by the winds and crab holes can be created, so clay pans really need a local to visit the pan and give the all clear. That visit can confirm whether the surface will support a wheel, and the recovery can be fast. On one occasion I drove a 3 tonne motor home from Marree to Lake Eyre South, spinning the wheels in the valleys in the morning, and came home on dry clay pulling up dust late afternoon.

 

Salt lakes are different, treacherous because they dry as a crust. The aircraft photo above is nowhere near the first; many have gone down to the belly before.

[Thruster88]

The clay pans I am familiar with in western nsw remain quite hard even when very wet. They don't have vegetation on them because water will not soak in so the soil is quickly to dry for plants to survive. Have had lots of fun drifting vehicles on wet clay pans even before drifting was invented.  

[onetrack]

Another interesting feature of claypans and salt lakes, is something called a seiche. This is a situation where there may be a pool of water up one end, or to one side of the claypan or salt lake - which initially appears to leave a dry area that can be driven on. So you select that dry area to utilise, thinking you're right, and the water will stay where it is.

However, strong winds will pick up the body of water, and drive it across the lake or claypan, with the body of water ending up in a completely different position, to where it was first sighted. This, despite the lake or claypan bed being dead level!

[walrus]

The locals have advised to wait a week. They should know. End of story.

Edited April 26, 2022 by walrus