Air cushion patterns
 

Looking for an online digram that shows the wake/wash pattern of a air-cushion vessel and or a hovercraft. Looking to compare and contrast such footprints with that of conventional, displaced vessels for a research project on riverbank erosion.

Re: Air cushion patterns
 

For a variety of wake images see: http://www.cyberiad.net/wakeimages.htm

Also see (for a variety of air cushion pressure distributions): "Wave Patterns and Minimum Wave Resistance for High-Speed Vessels", E.O. Tuck, D.C. Scullen and L. Lazauskas, 24th Symposium on Naval Hydrodynamics, Fukuoka, 2004. http://www.cyberiad.net/library/pdf/tsl02b.pdf

All the best, Leo.

Re: Air cushion patterns
 

got it. seems to be a lack of published material on transport carrying hovercraft.

jia

Re: Air cushion patterns
 

The "FAST" series of conference proceedings has a few references, but there isn't much, around as you said. Also look at CCdoT which assessed many different types of sea-lift vessels including hovercraft, SES and some other hybrids.

I've done some calculations for large (>10000t) hovercraft travelling at 100+ knots, but I doubt that anyone would want to build such frightening things.

All the best, Leo.

Re: Air cushion patterns
 

is CCDOT California DOT ?

If you have stats on a larger hovercraft sure I'd be interested in taking a look at these.

b/r,

jia

Re: Air cushion patterns
 

Sorry, CCDoTT is: "Center For The Commercial Deployment Of Transportation Technologies"

The conference I was referring to was: "High-Speed Sealift Technology".

The most important conference documents to get are at: www.ccdott.org/Deliverables/1997/task2.0.1/task2.0.1_m.htm

There are many references you can glean from:

Lazauskas, L.,"Hydrodynamics of advanced high-speed sealift vessels", www.cyberiad.net/library/pdf/llmsc.pdf

For an examination of (unachievable?) optimal pressure distributions see:

Tuck, E.O. and Lazauskas, L., "Free-surface pressure distributions with minimum wave resistance", www.cyberiad.net/library/pdf/tl01.pdf

Cheers, Leo.

Re: Air cushion patterns
 

It was a bit egotistical citing only my own papers. Anyone doing serious research on air-cushion vessels must look at the work of Lawrence J. Doctors who is probably the world's leading authority. In particular see: "On the use of pressure distributions to model the hydrodynamics of air-cushion vehicles and surface effect ships", Naval Engineers Journal, March 1993.

Now back to me again. :)

If you are interested in evaluating damage to the littoral zone by large fast ships, you might also consider the pressures induced on the sea-bottom. I've included some bottom pressure signatures for a large displacement vessel in: "The hydrodynamic resistance, wave wakes and bottom pressure signatures of a 5900t displacement air warfare destroyer", Dept. Applied Mathematics Report, The University of Adelaide. www.cyberiad.net/library/pdf/nibberluna0.pdf

Unfortunately I don't know enough to assess whether those pressures are significant in terms of disruption to sea-grass beds and the fauna that rely on them.

Regards, Leo.

Re: Air cushion patterns
 

thanks and obliged. after reading over your beta i read up on pressures and was wondering are studies available that shows the pressure bubble: depth and width of a hovercraft at different lift pressures ?

b/r,

jia

Re: Air cushion patterns
 

I'm not sure what you mean by the "pressure bubble". Do you mean contour plots of the over-pressure, or do you mean the elevations of the free-surface under the pressure patch? Or something else?

Leo.

Re: Air cushion patterns
 

leo,

Can't rightly say but contour plots of the over-pressure and the elevations of the free-surface under the pressure patch seems to meet the issue.

that is what can be shown of underwater pressure depth under a hovercraft.

b/r

jia