slick coating to save fuel???

[Steve L]

Yesterday Easy jet announced they are applying a nanotechnology coating to their aircraft to save fuel. Apparently it makes the plane pass through the air quicker and with less effort, thus saving fuel. Next thing, they'll have us pedelling a dynamo to save fuel!!

But having said that most people who polish their cars with silicon coating polishes are arguably doing the fuel saving job unwittingly.

Going way back to my teens, I used to polish the hull of my sailing dinghy to make it go through the water better. Wether it was .sycological or fact, I did seem to win races better.

I now use showroom shine dry wash on our car and diamond ice polish for post wet washing. I do it as it makes the car look very nice and well looked after.

But does a dirty car use more fuel?

 

[Parksy]

...........But does a dirty car use more fuel?

I bet it does when the bone idle driver goes 5 miles out of his way to get his car washed by those shifty looking Albanian asylum seekers for £3 and he sits inside the car leaving it running with the heater on hot and the stereo on full blast while six of them wash his car with grubby scratchy wash cloths

 

[Steve L]

I concurr on that Parkesy.
We've got a gang set up on the industrial estate in my town.
I know for a fact having had the industrial unit opposite, that they are not able to put a filter sump in to capture and clean the waste water. They operate outside the actual unit they rent and do nothing inside it!!
So I wonder just what their core business realy is

.

Due to the no washing of cars or caravans on our summer site, I have to use dry wash or the local english car wash.
Or covertly wash the car late at night or pre 6-30am. My service moto comes to mind. Who dares wins.

I wonder what the GPM is on an Easy Jet?

BTW I did get the letters the right way round

 

[mcghee]

There was one of the big manufacturers actually did some tests on this years and years ago. I think it may have been Turtlewax, although I could be wrong about that. Anyway, they reckoned that a clean but unpolished, unwaxed car used 4% more fuel than the same car polished and fully waxed.

 

[Lutz]

Unless you intend to drive at a speed similar to that of a jet aircraft, such measures are not going to make any measurable difference. The suggestion ranks on a par with discussions we've had on this forum about apparent aerofoil lift if the caravan has a nose up attitude, so I presume it was meant tongue in cheek.

 

[ProfJohnL]

Lutz got in before me

And likewise I think it is unlikely to make any practical difference at normal road speeds. Of more concern might the weight of mud plastered in the wheel arches, behind the bumpers and on the underside of of the car, but again its not going to be much

However I do recall a report that claimed Jaguar went for painted decals rather than stick on ones on the D type claiming it allowed the car to go 1mph faster because of the smother airflow!

 

[OmOnWeelz]

Going back some 40 years when I was a youngster, dingy's at our sailing club were prep'd to a glass like finish and then sprayed a familiar grey colour and it changed the speed of the boats and brought our club more wins. All was well until somebody at the local RAF base found that they were going through quite a bit extra of the special low drag 'Fast Jet' paint and the senior officer was also a member of the sailing club as were numerous RAF personell and he was able to add 2 + 2 and make 4. As the club got some good results I think he turned a blind eye to what was goig on.
So nothings new really

 

[Philspadders]

Smooth, polished oatings reduce drag. Reduce drag , use less power, use less power, use less fuel. Submarines use sonar absorbing coatings that are very smooth to reduce drag.

Now if the airspeed of an aircraft were to increase it would actually create more lift and the aircraft would climb, thereby requiring the pilot to reduce power. Its this that saves fuel.

Cars with smooth , highly polished surfaces do have reduce drag, but the wing mirrors and door handles, windscreen wipers all ****** it up.,

Unfortunatley with aircraft the physics are somewhat different where drag is required to maintain flight. I suspect only the fuse is polished and the wings are not. Elimintaing drag on the wings will alllow the boundary layer to seperate and the result will be a failure of Bernoullies law. Newtons 3rd law willl still help to the aircraft up but ultimatley it will stall and crash.

Heres a question. If an aircraft is on a moving conveyor belt and the belt and airspeed are the same ( the arcraft is not mmoving forward) will it achieve lift?

 

[Parksy]

To have a stab at answering your question Phil if the aircraft wasn't fastened down in any way as long as the conveyor belt is moving forward fast enough in the direction of flight to overcome drag then lift would be achieved I think.
Aircraft used steam catapults to take off from aircraft carriers, battleships and even armed merchant cruisers at one time and some gliders use a catapult arrangement to take off without a tug aircraft.
You can throw a paper aeroplane and it will glide so your hand represents the conveyor belt.
As soon as the airspeed is sufficient for air to flow over the wing fast enough the aircraft would be airborne although I'm not sure how long it would stay that way.

 

[Steve L]

Now Lutz and John are probably right that you wouldn't see a significant result on any one particular journey.
But I would suggest you could see a saving on a year's driving. Even if it's the cost of a couple of car washes it's still a saving. And I can see that this year we are going to see people scrimping and scraping like never before as their pound goes round less and less.

I much prefer to see a nicely polished car any day.

 

[ProfJohnL]

Hi Steve,

I can't deny that a nicely polished car looks better, and there can be no doubt that polishing and allowing the smoothest airflow over car will minimise air resistance losses, so a clean car will be more efficient.

But in reality I am very sceptical about the ordinary driver being able to conclusively establish any difference in fuel economy directly derived for the state of the paintwork. Not even over a year or mores motoring.

Other factors such as direction and speed of the wind, temperature, humidity and general traffic conditions will have a much greater effect, and mask any differences through polishing or not.

However, I have often convinced my self that my recently cleaned and polished car is quieter!

 

[Steve L]

I know what you mean John

My car was clean two days ago.

At this rate I'll be cleaning the car twice a week

After a yer of that the car might need a respray

Oh sod it, I'll *** out and buy another gallon of diesel to cover the fuel saving

 

[ProfJohnL]

Oh steve,

Now I see where you are going wrong.

"Oh sod it, I'll *** out and buy another gallon of diesel to cover the fuel saving"

If you need to buy fuel to cover a saving, then its actually a loss, not a saving,

and have you also factored in the cost of travelling to your cheapest loacal filling station just to buy that extra gallon.