AQUAPLANNING IN BELGIUM
Discussion
Driving back from Mons Belgium in the company Focus Diesel at 120 kph and in difficult driving conditions and the warning signs about aquaplaning on the overhead. However, the Focus was fine through any standing water at 120kph and so were the white vans. Then we start to slow down and there is a new Porsche 911 rear end into the barrier and badly damaged. He may have been over 120kph, but not much as there are so many cameras around and the density of the traffic does not allow speeding. The standing water was about 100m before the spin and in subsequent standing water the Focus passed no trouble. I can only assume it was not a 4WD or that the tyres were crap. I was really surprised to see the car had spun as I would have thought, like the Focus and vans, it would literally sail through this type of standing water. PS: I don't post much on here, but enjoy reading and thought your Porsche aficionardos would be interested.
Even with new tires on either of my Porsches I can sometimes detect the early signs of hydroplaning if I let my car's speed get too high. And I'm not talking about autobahn too high of speed either I'm talking about staying at under 75mph down to even 65mph.
Thus I always when the roads are wet try to keep my car's speed down.
I've never had it happen to me but I have watched a couple of cars leave the road due to hydroplaning and it happens very quick. Since the tires are not making contact with the road braking or steering have no real effect and the driver (and any passengers) is (are) just along for the mostly likely very bumpy ride.
My Porsches are the worst for this tendency to hydroplane of any cars I have owned, except possibly a Dodge D200 pickup truck with fat tires and no weight over the rear axle. That thing would hydroplane on a humid day.
Thus I always when the roads are wet try to keep my car's speed down.
I've never had it happen to me but I have watched a couple of cars leave the road due to hydroplaning and it happens very quick. Since the tires are not making contact with the road braking or steering have no real effect and the driver (and any passengers) is (are) just along for the mostly likely very bumpy ride.
My Porsches are the worst for this tendency to hydroplane of any cars I have owned, except possibly a Dodge D200 pickup truck with fat tires and no weight over the rear axle. That thing would hydroplane on a humid day.
Oh! Boy looking forward to all this aquaplaning stuff!! My fettled Aston V8S was pumping about 470 brake. Going on a jaunt with Petrol Head Nirvana up and over the Alps wearing nothing but Potenzas in serious rain I can honestly say that they never ever let go. So in my soon to be GT3 what can I expect?
IIRC, aquaplanning can occur at about 8 x the square root of the tyre pressure, give or take 5 mph, depending on tread depth. So anything more than 48mph on a well treaded tyre inflated to 36psi, or above 43mph on a lightly treaded tyre, could make for an interesting moment in standing water.
Happy to be corrected by someone smarter than me!
Happy to be corrected by someone smarter than me!
I have 315s on the back of my C4S and, despite the 4WD, it felt all over the place on the M20 when the rain was coming down a couple of weeks ago. It was torrential, but white van men were going over 80mph and i was having to back off at that speeds as i was getting silly having to make minor corrections with the steering!
Funnily enough, on the same stretch about 2 years ago i saw a 911 in the barriers on a rainy day. Now it makes sense!
Taking the GT3 on Cups to Snett on Friday... bring on the hurricane!
Funnily enough, on the same stretch about 2 years ago i saw a 911 in the barriers on a rainy day. Now it makes sense!
Taking the GT3 on Cups to Snett on Friday... bring on the hurricane!
This thread has just brought back a bad memory! (Although the ending was happy.) 27 years ago, when I was 20, I had an Alfasud Sprint with relatively fat tyres for that era . My sister was 18 and had just passed her test and had just bought her first car a 0.9l Fiesta! I don't recall where we were going, but for some reason we had to go in two cars and it was absolutely lashing it down with rain and there was standing water everywhere. She was ahead of me as we passed through our high street and I started to feel my car aquaplaning / torque steering. At 25-30MPH it was fun. I noticed my sister was pulling away... Then I remembered, as we leave our village, the 30MPH zone becomes national speed limit (it's 40 today - boo) and after a small hill, a horrible right-hand bend with an adverse camber. My sister was away - I just could not catch up with her to flash her and warn her about the right-hand bend. The rain was so hard, and the road a river, I just about maintained my speed but certainly couldn't get any traction down to increase speed. I can remember with such dread the helpless feeling I had as I was certain I would brow the hill before the bend and see her red Fiesta in the ditch. She wasn't there! Phew - she was now 1/4 mile further up the road! Her skinny tyres just sliced through all the water like she was driving on rails. When I eventually caught up with her at our destination, having nearly ruined my pants and fallen off every bend along the way, she calmly asked, "What happened to you?".
Thanks for jogging my memory! Happy days...
Thanks for jogging my memory! Happy days...
speedyellowrs said:
IIRC, aquaplanning can occur at about 8 x the square root of the tyre pressure, give or take 5 mph, depending on tread depth. So anything more than 48mph on a well treaded tyre inflated to 36psi, or above 43mph on a lightly treaded tyre, could make for an interesting moment in standing water.
Happy to be corrected by someone smarter than me!
I'm confused as to why that calculation isfor pressure and speed? I'm sure many of the white vans mentioned are running pressures not disimilar to the sports cars, but with vastly different abilities to move water and resist aquaplaning.Happy to be corrected by someone smarter than me!
robgt3 said:
Oh! Boy looking forward to all this aquaplaning stuff!! My fettled Aston V8S was pumping about 470 brake. Going on a jaunt with Petrol Head Nirvana up and over the Alps wearing nothing but Potenzas in serious rain I can honestly say that they never ever let go. So in my soon to be GT3 what can I expect?
You really want to know? http://rennlist.com/forums/991-gt3/801096-porsche-...
The guy has gone back to (me thinks) Aston.
Seriously, I'm just over the county line from you. If you need someone to drive it back from the OPC, I'm more than willing.
Infact I'll scrub those tyres in for you a wee bit as well, so just leave her with me for a month or so ...... well until after Christmas maybe.
thegoose said:
I'm confused as to why that calculation isfor pressure and speed? I'm sure many of the white vans mentioned are running pressures not disimilar to the sports cars, but with vastly different abilities to move water and resist aquaplaning.
Hi Marcus,I believe the size and shape of the contact patch is also a factor. The long thin contact patch of a van tyre will be less likely to aquaplane than the short wide one associated with a sportier tyre.
Again, happy to be corrected by someone with better engineering knowledge than me!
SYRS
robgt3 said:
Oh! Boy looking forward to all this aquaplaning stuff!! My fettled Aston V8S was pumping about 470 brake. Going on a jaunt with Petrol Head Nirvana up and over the Alps wearing nothing but Potenzas in serious rain I can honestly say that they never ever let go. So in my soon to be GT3 what can I expect?
You'd definitely have been ok in the Aston as you have a great lumping motor pushing the tyres through the surface water. Hence (partly) the reason the Focus was ok in the OP (helped also by thinner tyres). Any mid / rear engine car (especially those with wide tyres will be at risk).I once wrote off a perfectly good 348TS in Switzerland after getting caught out in a freak rain storm in Switzerland... Nothing quite like aquaplaning at about 70 odd, spinning and then gliding down the motorway sideways. I came to rest on the hard shoulder having taken out a few saplings en route. Most amusing of all was that the Swiss authorities sent me a bill for thousands to 'repair' the grass and trees!!!
Fricken Swiss - gotta love um...
Be careful indeed. 2011 in the 997 GT3 on the way back from Le Mans and I arrived back in Blighty to lots of rain and pools of standing water. Never having driven the GT3 in that much rain I had a couple of real ring tightening moments as the back slithered away. I couldn't keep up with my mates and in the end I thought I was going to crash so I radioed the guys to wish them well and pulled into the inside lane at about 50mph, and even then the rear end felt squirmy. When I compare that to a rock solid Chrysler Voyager at 115mph in a proper Euro storm in Germany a few years back and I'm just glad my GT3 experience didn't involve Armco. The cause is mainly to do with wide tyres, light weight body and the rubber cut. Interestingly my super light and over powered Ginetta G33 did the 'run' a couple of years before and covered the entire return trip in torrential rain without a single moment. It's an issue well worthy of the occasional reminder to new 911 owners.
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