AirTabs shown to work by respected EM member

[freebeard]

Gee Frank, you're getting all serious and stuff.

Originally Posted by euromodder

I've had tiny VGs on Hägar - mirror and A-pillar.

I've been thinking about Gerrelt's Garage -- Reducing Windnoise / Raingutter Fillers and Gerrelt's Garage -- Vitaloni California mirror on standard stalk.

Do you have a search term or reference link?

[Frank Lee]

Gee Frank, you're getting all serious and stuff.

Don't worry- it'll soon pass!

[slowmover]

Originally Posted by freebeard

slowmover -- There's something I've been wondering...

Suppose the trailer had a retractable skid at the rear, and some feedback loop that fed off the difference between the angle of the front wheels and the angle of the tongue at the hitch. Wouldn't judiciously applied drag cause the trailer to fall in line behind the hitch?

If the contact pad was titanium, as a bonus you could throw sparks at any tailgaters.

Manually slam the trailer brake control and nail the throttle. Since the first days of trailer brakes.

There have been some other electro-mechanical devices tried over the years, but Americans and the DOT has little interest. In Europe there are a few electronic devices now in place to correct sway (but the geometry of how they do the lash up is different, and predicated on some different assumptions about towing).

Sway is a subject rather past a bit of tail wagging. All trailers do it, it is only how much. A fair sized grey area, overall.

Titanium sounds fun, but wouldn't magnesium be MORE fun?

.

[RedDevil]

Would it be possible to kill the sway by coupling the wheels together, like when using a diff lock?
If the wheels on both sides are forced to turn at the same speed that would kill the sway.
It better be unlocked in tight corners though to stop it from killing other things than sway.

EDIT never mind, wouldn't work. The trailer would resist changing direction, pulling the towing vehicle sideways thereby inducing rather than killing sway.

[baldlobo]

i think everyone missed the part of the manufacture website that says they only do something over 35mph(60kph)

so who here drives 35 or over in a city(without pulse and glide) ..... me thinks they suck back more then they give.

[Julian Edgar]

Here I am back again - only just saw this thread.

I agree that an A/B/A test would be more valid than what I have done.

But also a bit more on the background. I live 80km (50 miles) north of Canberra, Australia. I drive into Canberra and back 2-3 days a week. There is no traffic - I don't even reach a traffic light until about 75km into the trip. Sometimes I see only 5 cars in the first 50km.

It is just an empty country road driven at a constant speed - 100 km/h.

I also drive from here to Sydney and back - freeway all the way (it's about 250km each way, with only the final part in city traffic).

I owned the car for about 10 months before adding the vortex generators.

I know the fuel economy on these trips very well. I can immediately see by the fuel economy if my wife has filled with 95 versus 98 octane, and I can see the difference in fuel economy that my 0 degree C mornings are having. (40 degrees C in summer, 0 degrees in winter.)

The fuel economy has never been as good as with the vortex generators fitted. Never.

Now: here's the joy for you sceptics. I had a cam belt change at 100,000km, about 2 weeks after I fitted the vortex generators. I saw the improvement in fuel economy straight after I fitted the VGs, but the confirmation over the 10,000km since has been with the cam belt changed and the VGs fitted. So perhaps some of the improvement is that cam timing is changed a fraction, i.e. belt stretch is no longer there? To me it doesn't seem likely, but it is possible.

Oh and the kit price people are quoting is for heaps of the things. I think mine cost me a few dollars each - but I did buy them years ago.

[MetroMPG]

As much as I blather about A-B-A tests, I wouldn't rule out long distance (and also long term) testing as a way to measure meaningful trends in fuel economy... provided it's a big sample.

There are a few members here who are meticulous record-keepers (recording the results of every single commute, both ways, with environmental and other info as well) who can spot a deviation from the norm just because the sample is so good.

[RedDevil]

But even a big sample can give warped data.

Take my fuel log (sorry to repeat myself from page 1); up to a point all fillups were worse than 50 mpg, after that all were better.
It was not the weather (it kept freezing for months and even now the temp averages below what it was when I got the car in October). It wasn't driving style (or so I believe). It wasn't the HIDs or LEDs, It certainly wasn't VG's.

So what does that prove? Nothing but that fuel logs are an indication, probably, but no certain proof of the effect of a modification.

[aerohead]

Originally Posted by Julian Edgar

Here I am back again - only just saw this thread.

I agree that an A/B/A test would be more valid than what I have done.

But also a bit more on the background. I live 80km (50 miles) north of Canberra, Australia. I drive into Canberra and back 2-3 days a week. There is no traffic - I don't even reach a traffic light until about 75km into the trip. Sometimes I see only 5 cars in the first 50km.

It is just an empty country road driven at a constant speed - 100 km/h.

I also drive from here to Sydney and back - freeway all the way (it's about 250km each way, with only the final part in city traffic).

I owned the car for about 10 months before adding the vortex generators.

I know the fuel economy on these trips very well. I can immediately see by the fuel economy if my wife has filled with 95 versus 98 octane, and I can see the difference in fuel economy that my 0 degree C mornings are having. (40 degrees C in summer, 0 degrees in winter.)

The fuel economy has never been as good as with the vortex generators fitted. Never.

Now: here's the joy for you sceptics. I had a cam belt change at 100,000km, about 2 weeks after I fitted the vortex generators. I saw the improvement in fuel economy straight after I fitted the VGs, but the confirmation over the 10,000km since has been with the cam belt changed and the VGs fitted. So perhaps some of the improvement is that cam timing is changed a fraction, i.e. belt stretch is no longer there? To me it doesn't seem likely, but it is possible.

Oh and the kit price people are quoting is for heaps of the things. I think mine cost me a few dollars each - but I did buy them years ago.

Julian,forgive me,as I'm quite late to the party,but can you please tell us the kind of car you're driving?
My mind was thinking in the direction of a notchback.I wanted to make sure.Thanks!

[freebeard]

Julian E. -- I believe you. But then I simutaneously believe in 'gut feelings' and 'confirmation bias'.

Are you familiar with the work of Yoshi Suzuka? He's been at it since the mid-70s, like you and aerohead, and talks at one point about up to 1500 component tests a month, using miniatures for preliminary work before moving to the full scale tunnel for fine tuning, and how power required grows with the cube of the volume of air (or something).

Late one night, in a certain frame of mind, I got to thinking about wind tunnels with multiple propellers needing diffusers to smooth out the resulting flow and I wondered—why not paddle wheels? I did this and posted in another thread:


More lately, I'm thinking only two wheels, at the 'stern' and shorter, thin walls with fillets that concave up against the sweep of the paddle wheels.

Less turbulence? On-topic for air tabs?