Gas mileage discussion + thread collection

[Ol'fogasaurus]

"It makes a big difference in cruise kpa if you draft a vehicle in front of you"

I'd be very careful about doing that as some vehicle's designs give off a lot of turbulence which can make a light toy dance a lot. In one of my few trips in the blue buggy I got into a couple of those situation during the end of a workday on I-5. I'd be even more cautious if my buggy only had a hoop for decoration as in a rollover, they just lay down flat because of no real strength and they (most of t he hoops I have seen) are already angled to the rear somewhat.

I know of one death caused by the hoop not helping the driver.

Lee

[oprn]

Yes it is true that drafting makes a difference. It is also true that it makes our light Buggies dance. As for a roof... I don't know how much difference that would make. Not that much I suspect. I am considering a 3" shorter windshield to see if that would improve the drag. I suspect the windshield is one of the biggest offenders for wind resistance.

The change from the '67 swing axle (4.12 gearing?) to a late single side cover IRS (3.87 gearing?) has not been that dramatic.

[Bruce.m]

https://youtu.be/Ez1_8pj9aVc?si=v7ukNMYfwqrm4cer

That’s the YouTube video

[Ol'fogasaurus]

Watched the video... interesting but one thing didn't get discussed and that was the fuel tank which changes the weight up front as the level of fuel in the tank changes. Would it make a difference... probably but not much... maybe.

My blue buggy has the tank in the rear for several reasons and my black buggy has the tank in the rear as the body isn't well set up for a tank up front (both buggies are build/rebuilt for sand riding.

Again, the video was interesting other than the metric definitions .

Lee

[oprn]

It is interesting! I would never have guessed that side windows would have been the most effective drag reduction! Not surprising to me that the frontal area and the windshield shared the drag split fairly evenly. One would then wonder what the model would have looked like with no windshield. Perhaps the human forms and the rear seat upright would have nearly made up for the drag lost by the absence of the windshield.

There is no free lunch I suspect! The statement he made about the highway use of these cars is way above and beyond what they were designed for is true. I had not given that much thought.

[Ol'fogasaurus]

It is interesting! I would never have guessed that side windows would have been the most effective drag reduction! Not surprising to me that the frontal area and the windshield shared the drag split fairly evenly. One would then wonder what the model would have looked like with no windshield. Perhaps the human forms and the rear seat upright would have nearly made up for the drag lost by the absence of the windshield.

There is no free lunch I suspect! The statement he made about the highway use of these cars is way above and beyond what they were designed for is true. I had not given that much thought.

Flat or straight (not arced), the windshield does cause turbulence of the wind as it comes around the edges of it. The turbulence also can cause a suction like affair as it starts to curl back against the glass.

While I don't recommend doing it but if you put your arm out the door window you might get a small idea of what is going on with air flow. Different speeds give different flow patterns and pressures at speed changes.

I've talked about this before but with tubular sand rails, mounting the radiator facing the side of the vehicle causes the airflow not to go through the radiator. I have seen two smaller radiators mounted sideways, one on each side of the rail and still not work well. The same with adding scoops to the radiator does not work much either.

Also suspension changes could/should be in the discussion. For example, swing axles could have different draws due to the tires angles change (not fore and aft but side swings) when going up and down and the tires contact with the pavement changing. IRS is not as strong in this way but there is some "cause and effect" also.

7-28-2010 007 (2).JPG

The glass buggy body with no top does not give much support to the pan now that the Bug's body is not there to do support and load transfer. On the street the pan and glass body is just about as weak as it is off-road. The spot welding needs to be updated, for the pan changes, to better/stronger welds. Then there is the proper cage to cover not only protection like the body did but load transfers (front to rear, side to side and diagonal/twisting and shock loading) also.

This can go on and on but again, the video is interesting.

Lee

[Ol'fogasaurus]

012 - Copy.JPG

A look at the beam adjuster. I was playing with this around 2012 so more info should be in my black buggy build.

Lee

[oprn]

I spent quite a but of time riding in our open Buggy both feeling the shape of the wind with my hands, with a streamer on a stick at all points that I could reach and with a temperature probe to learn what the air is doing. It was a real education to say the least. The main purpose of my experiments was to try and determine the possible effects of changing from an upright fan engine to a crank mounted fan. I can fully understand what you are saying about the difficulty of mounting a radiator at the rear of our cars. The same is true for mounting an intercooler back there. There is no predictable airflow direction behind our cars! Any external cooling device we add is going to have to be force fed air at all speeds! I have also seen wings added to the rear of Buggies and unless they are mounted 3 feet or more above the rear of the Buggy they will do nothing at all! Strictly eye candy.

As for adding a roll cage to an open Buggy, I have no experience with that. The only thing I will say is that I do not think it would improve the drag issue in any way. However it may not be a big impediment due to the fact that the air in that area is mostly just turbulent and in some places relatively stagnant.

[Ol'fogasaurus]

Like most everything else, the cage can and does make some drag to the buggy assy. The weight of it also has some effect too but the cage is for protection (and for some... looks) so, if done right, it stiffens up the pan where the missing structural body isn't there to help.

Most all choices often end up being safety or looks but I usually pick safety assuming I can do it or have the money to do it. If you look at a sand rail... they probably started when the buggy body takes a dump (gets caught up in a wreck for instance) and all that is left is the structure.

Lee

[oprn]

In an effort to get this thread back on track, I filled up in town, can't trust this speedometer, not even close to accurate, 18 km home according to Google maps... will see if the weather is decent enough to put a few miles on today.

[Ol'fogasaurus]

Like most everything else, the cage can and does make some drag to the buggy assy. The weight of it also has some effect too but the cage is for protection (and for some... looks) so, if done right, it stiffens up the pan where the missing structural body isn't there to help.

Most all choices often end up being safety or looks but I usually pick safety assuming I can do it or have the money to do it. If you look at a sand rail... they probably started when the buggy body takes a dump (gets caught up in a wreck for instance) and all that is left is the structure.

Lee

Pretty much everything has "cause and effect", and it must be considered. Windshields, for example, have a large effect. No windshield, then your body does have an effect also. The wind circles around the windshield and your body (and hair) are/can be aware of it as either or both causing a drag of many sorts. The body and it's drag in the front, along the sides and the potential vacuum in the rear have effects

One of my jobs, when I was working, was to deal with "cause and effect" (to call or point it out and some of it was very detailed at times) of things even if it wasn't obvious. Some of the discussions at my desk or in rooms could get heated and/or loud. Vocabulary was often another thing. Words, the order of wording and the meaning of words (words can and do have a different meaning everywhere even locally) and the tone and use of the words need to be determined at times.

Like OPRN said, back to other things.

Lee

[oprn]

I was thinking seriously about taking 3" off the height of the windshield for drag reduction. Right now the top bar of the windshield frame is dead center in my vision. I know that the windshield is at t least 50% of the frontal area. Someone on another site pointed out that although the wind and rain would still go over our heads, the rocks, bees and grasshoppers would not... and I might add from personal experience... neither would the hail stones!

So - the windshield stays as is for now. If I slouch down a bit I can look under it and if I sit at attention I can look over it...

It rained most of the day yesterday so no mileage run. Ah well, we need the rain!

[Ol'fogasaurus]

I was thinking seriously about taking 3" off the height of the windshield for drag reduction. Right now the top bar of the windshield frame is dead center in my vision. I know that the windshield is at t least 50% of the frontal area. Someone on another site pointed out that although the wind and rain would still go over our heads, the rocks, bees and grasshoppers would not... and I might add from personal experience... neither would the hail stones!

So - the windshield stays as is for now. If I slouch down a bit I can look under it and if I sit at attention I can look over it...

It rained most of the day yesterday so no mileage run. Ah well, we need the rain!

Aw yes, but is that the only answer?

First of all your vision is most important (especially with insects and frozen stuff) so it's height is important.

Even without the windshield, there is air curling at the dash's top end of the hood so that is also something to think about.

Lowering the seat some to accommodate the windshield height may help or... can make things worse.

Does the windshield stand straight up or is it "laid back" some (I have seen both on buggies). Straight up I think is worse than slightly laid back some.

Remember that both sides of the windshield have air and other things wrapping around it besides just the top which can affect you and passengers.

https://en.wikipedia.org/wiki/Quarter_glass

https://www.bing.com/images/search?q=wi ... RE&first=1

I did a quick search on "wing windows" and found these but the wing windows here were only for motorcycles. Maybe that might work as they are similar to what we did back in the mid-1900s. There are pictures of the wing windows in these posts... if you look closely.

If this is a street legal buggy, your local safety rules must apply. You should be able to get a copy of what is needed from the central license point. Where I live "yes" and "no" are very important.

The only other option (if it is streel legal) is a helmet with a shield on it . This is not legal on a car in a lot of places so checking it out should be used.

[oprn]

Yes the windshield does slope back a bit. More would help though.

Wing windows are not likely to result in any appreciable drag reduction but I have considered them for helping with wind shear across the Buggy when driving in a cross wind. The person on the windward side gets hammered pretty bad, ear plugs are needed to keep the wind noise down when this happens.

I have read through the regulations and other than the type of glass for the windshield, nothing else is specified. There are some odd things in there though but no need to get into them here. I have not seen anything about helmets one way or the other.

[Ol'fogasaurus]

Yes the windshield does slope back a bit. More would help though.

Wing windows are not likely to result in any appreciable drag reduction but I have considered them for helping with wind shear across the Buggy when driving in a cross wind. The person on the windward side gets hammered pretty bad, ear plugs are needed to keep the wind noise down when this happens.

I have read through the regulations and other than the type of glass for the windshield, nothing else is specified. There are some odd things in there though but no need to get into them here. I have not seen anything about helmets one way or the other.

The idea of the helmet instead of a windshield in a car (a dune buggy for instance) wasn't a for fun thing but more of a curiosity question so I did another search and found this:

https://www.bing.com/search?q=wearing+a ... cc=0&ghpl=

Lee