Idea Release: vehicle efficiency

[Flying Binghi]

And,.....your point?

 

A bit remiss of me there.

 

Many years ago I had a small motorbike which I rode long distances. Overtaking large trucks doing over 80km/hr was a minor study in truck aero dynamics.

 

Dutchdivco, you have touched on the front and rear of the truck though have you considered the possible side forces of the prevailing winds ? and re the bike, I have a vague memory of hitting a major pressure wave/ increased wind speed (?) about a fith of the way back from the front of the truck (bike overtaking from the rear) On some occasions my underpowered bike could barely overcome the increase in wind.

[Roadam]

All that of course point out that trucks are big and bad and ugly in terms of aerodynamics. But any sort of tunnel trough it would probably just add more drag. It may be better to attach a sharks tale to the truck :)

[Flying Binghi]

It may be better to attach a sharks tail to the truck

 

Might make the steering a little giggle headed when the tail caught the wind :)

 

Sharks mouth and gills...Hmmm.

 

I wonder if there is much energy in the heat of the road ? (clear sky, full sun) Make the road one 'side' of the tunnel perhaps - Ground hugging skirts length ways between the tyres...

[Roadam]

I do see that formula 1 racecars regularly incorporate such a tunnel in there designs. I also see that after someone put a fan in the tunnel, they outlawed putting any kind of mechanical device in there, which leads me to think it must have given an advantage. I find this hopeful.My truck is not anything like a formulae 1 race car, aerodynamiclaay. its about the opposite. As I say, I'm hoping, maybe, thats a good thing. I'll have a significant sized negative pressure zone, with a, I hope, significant amount of negative pressure.

 

With a bit of digging I can say that what they banned from formula 1 is ground effect. See lotus 78 in wikipedia. Short version is that with creating low pressure below the car helped the car stay pinned to the ground in even the fastest corners. So some later models used a vent to additionally vent the air out ot from the underside.

 

Also, I dont see any point of creating a tunnel trough the truck. The only thing it may do is create more drag. If you want to stick to the road create a low pressure below trough lowering it, but that would basically eliminate all the clearance :).

 

The areas on the truck that do most to the aerodynamics are front and back section.

Aerodynamic improvements & flow control boost fuel efficiency in heavy trucks

[Zythryn]

Again though, you would most likely loose more energy overcoming the added drag from the 'skirts' than you would gain from the device.

In all of the above ideas, you are adding weight and/or drag.

For example, the OP idea of getting 100lbs of lift for the vehicle. How much weight would be required for the structure, and how much additional drag? As a practiical issue, would you be adding any width to the vehicle, and if so, how much?

[Dutchdivco]

Not sure I'm following some of the points,here.The amount of weight I'm adding is very little.Certainly less than 100 lbs.Not using "skirts", though I am lowering the truck some, it won't be a "lowrider", tho! Anyway, its an experiment and I'll see whether it improves things, or not.I still THINK, at a minimum, it should reduce drag. I must admit tho, when i start researching aerodynamics at a certain point my eyes glaze over.Jim

[Flying Binghi]

Not sure I'm following some of the points,here

I must admit tho, when i start researching aerodynamics at a certain point my eyes glaze over

 

Dont worry, plod on.

 

Speaking of things aerodynamic - it was a couple of push bike mechanics who first designed and flew a heavyer then air flying machine. At the time there was a 'scientific' aircraft design effort going on involving large floating launch barges on rivers etc...

[Zythryn]

Lowering the air drag is a great way to increase gas mileage. If that is your goal, you are making it too complicated on yourself.

Have you looked into what is necessary in order to get 100 lbs of lift? I am not sure myself, but I am curious.

[Dutchdivco]

Not sure why you say I'm making it too complicated on myself. I maybe didn't explain; I raised the body off of the frame, for other modifications I was committed to making, and looking at the frame, and some of the other things I'm doing, it just kinda seemed to naturally fit in with it.Without going into a lot more detail, suffice to say, the tunnel or duct isn't that much work, time money or additional weight.So, if it doesn't give me much benefit at all, it won't be a terrible loss. Jim

[Roadam]

I am not sure where exactly you would put that duct. Can you take a picture or two. :phones:

[Dutchdivco]

Have some, not sure it would help, how to load it, take ur pick. Its not rocket science.Its on older truck, has an actual full frame, so I was able to disconnect the body and lift it off the frame; Axles and drivetrain intact with frame.Its going to go between the framerails.Will have bellypan, which will double as bottom of duct.Jim