I have no knowledge here...but intuitively that looks like a random number generator...(even assuming square root )9 times the square of the tyre pressure: 2.5 bars = 36 psi = 9 x 6 = 54 mph.
I don't know where those numbers come from, but surely, weight of the car, depth of water, as well as the design pattern of the tyres play a HUGE role. You can't seriously mean that 54mph is some sort of magic speed you can keep, regardless of the other data...9 times the square of the tyre pressure: 2.5 bars = 36 psi = 9 x 6 = 54 mph. Not many cars travel in the outside lane at less than 54MPH - and there is only so much that narrow tyres can do! It looks like the driver might have been a passenger for a while. I bet it gave the guy behind quite a shock as well.
All that doesn’t change the fact that the i3 with narrow front tyres has better aquaplaning characteristics than many other vehicles I have driven/tested over the years.Total width of the tyre is pretty much irrelevant for aquaplaning resistance compared to the tread pattern design.
This is why aquaplaning resistance is one of the metrics measured when testing different tyres - of the same size against each other. Sure, if the tread pattern is identical a narrower tyre will do slighty better but not much, and the difference is smaller than staying with the same size tyre with a different tread block design more optimised for removing water.
Tyres with tall tread blocks with sipes and wide gaps between blocks tend to be best for aquaplaning reistance as they give the water a lot of room to displace within the tread of the tyre before aquaplaning can initiate.
So winter/all season tyres can do quite well here as they tend to have tall tread blocks with sipes and have a lot more water channels and less rubber than a summer tyre. Most summer tyres have large flat areas of tread with no sipes that can't displace large amounts of standing water.
54mph is a calculated/approximate speed based on the lower of the two tyre pressures for an i3. In truth, the calculated speed is slightly higher as the actual calculation is:I don't know where those numbers come from, but surely, weight of the car, depth of water, as well as the design pattern of the tyres play a HUGE role. You can't seriously mean that 54mph is some sort of magic speed you can keep, regardless of the other data...
Fair enough: I will put my hand up to one basic school boy error. For 54 mph read Knots, so the speed for an i3 is just over 60mph.I fail to see how a simple equation like Vp = 10.35*sqrt(pressure in psi) can give any meaningful insight into the aquaplaning characteristics of a car/tyre when it takes nothing about the tyre into account except the pressure. Where does the 10.35 come from ? I also notice this equation is lifted directly from the Wikipedia article and the section of the article says "This section does not site any sources". So I call BS on this dinky formula. It might as well say that red cars aquaplane more easily than blue ones. Tyre pressure is a minor factor relative to tread depth and pattern.
Perhaps quoting Wikipedia is not the best scientific evidence and is not the best answer to my question... Anyway, I guess that the calculation is still wrong, because as I said, it doesn't take all the parameters into account. Weight plays a role, just like the tire pattern. I know very well what aquaplaning is and what causes it, as well as the fact that weight alone is not protecting you from it, but ALL parameters must be used in a calculation, INCLUDING weight, if you want to come up with such precise figure. So, I strongly question your calculation, as it is far too generic. In fact, what you don't quote is that even the Wikipedia reference is warning you, saying that:54mph is a calculated/approximate speed based on the lower of the two tyre pressures for an i3. In truth, the calculated speed is slightly higher as the actual calculation is:
Vp = 10.35 Square Root of the Tyre Pressure in PSI
There is science underpinning the aquaplaning/hydroplaning formula.
The possibility of aquaplaning is instilled into all pilots from day one of their training. Weight alone will not stop a machine from aquaplaning. I have experienced it twice on very wet (debatably, flooded runways) with an aircraft landing weight well in excess of 100 Metric Tonnes. Modern runways are now grooved but not all airports and runways can be considered modern. It will not surprise you know that crews carry out some very detailed calculations before landing. In the case of a very wet runway, the maximum landing weight of the aircraft would be markedly reduced below that of the same aircraft on a dry runway.
It happens to small aircraft as well:
A wet runway and wind gusts made an Air Force Thunderbirds F-16 Fighting Falcon slide and flip after landing during a routine training flight.www.military.com
So be careful spreading that as absolute facts, because it isn't.Wikipedia said:However, the above equation only gives a very rough approximation. Resistance to aquaplaning is governed by several different factors, chiefly vehicle weight, tyre width and tread pattern, as all affect the surface pressure exerted on the road by the tyre over a given area of the contact patch - a narrow tyre with a lot of weight placed upon it and an aggressive tread pattern will resist aquaplaning at far higher speeds than a wide tyre on a light vehicle with minimal tread. Furthermore, the likelihood of aquaplaning drastically increases with water depth.
Meaning that visibility was too bad, the pilot did not pay attention to warning signs and lost contact with runway, landed using only instruments, had no visual reference before touching the surface, so he had too high speed. Simply put it, he should have aborted the landing in time, and should have followed procedures, landing elsewhere or whatever routines they have. The wet runway was NOT the cause of the accident, planes land on wet runways every day somewhere on this planet and they don't crash.Military.com said:"Contributing factors to the accident included: environmental conditions affecting vision, misperception of changing environment, and failure to follow procedures," .
"We land in rain all the time."
Applying common sense is better than applying that formula, even if it comes from NASA. It is also different if you hit the water at high speed and you have tires which don't rotate yet (landing plane), compared to tires which rotate already (car).Fair enough: I will put my hand up to one basic school boy error. For 54 mph read Knots, so the speed for an i3 is just over 60mph.
It does NOT mention knots, it says mph. Reducing speed is the only sensible think you can do when you drive a car. You can't reduce the speed of the landing plane because you will crash. Leave out the aviation issues, the problems are different."skybrary" said:"Aquaplaning is also highly relevant to cars at speeds as low as 40 mph."
Can't disagree with that!Bottom line is if you don't want to aquaplane - (in any car) - reduce speed according to the conditions.
And if you do aquaplane that tells you that you are going too fast.
I'm not sure that is correct - if you look at the derivation of the formula it is based on the weight /surface area expressed in psi. This may be similar to the tyre pressure in aircraft but not on cars, and certainly not EVs. In my case I'm running at 45 rather than the recommended 36 (which may be based on weight/surface area), but increasing tyre pressure for a given mass of car will make no difference to aquaplaning.Vp = 10.35 Square Root of the Tyre Pressure in PSI
Driving faster increases aquaplaning risk, I have no argument with that. If it's wet, slow down.Might I respectfully suggest that you search for Horne's Formula. I chose Wik as it a source that many people are familiar with. Here are other sources that you might not have seen before (there are many others with lots of scientific references):
The original research into aquaplaning tyres was carried out by NASA in the 1960s. I suggest that you look at page 5:
Of course, it is entirely up to you whether you think what I have posted is BS. All I am saying is that when I am driving on very wet roads, it is at the back of my mind that at high speeds on wet roads there is the possibility of aquaplaning. Sadly, from experience, many drivers on wet Motorways have a different opinion.
In other words the fudge factor at the front depends on the type of tyre and isn't just some magic number. What a surprise, this is exactly what I already said...tyre design is the most important factor.V = 9 x √P
This formula is based upon the validation of hydrodynamic lift theory by experimental evidence. For many modern tires the constant maybe closer to 6 or 7 rather than 9.