Aerodynamics / MPG increase - up 16%

[hoser]

Originally Posted by Augster59

Hello, i'm Augie in Salt Lake City. all new to this forum and been listening in{well reading anyway}on this is very interesting subject. I was thinking of a spoiler under the front bumper would help? something like the old locomotives used! Well just a thought, and this site has been so very helpful to me on ideas to my up-comeing work on my school bus...
Thanks to you all.

I was thinking the same thing add something to the bottom of the bumper, both my 87 chevy pickup and my 90 Suburban have them mounted below the bumper they are plastic and wrap around the sides.

[pete c]

Originally Posted by Augster59

Hello, i'm Augie in Salt Lake City. all new to this forum and been listening in{well reading anyway}on this is very interesting subject. I was thinking of a spoiler under the front bumper would help? something like the old locomotives used! Well just a thought, and this site has been so very helpful to me on ideas to my up-comeing work on my school bus...
Thanks to you all.

That spoiler they tacked on the front of old steam locomotives....Yes, it was made to deflect stuff, like cows. I am fairly certain that they hadn't invented drag coefficient yet.

[pete c]

Originally Posted by Eric von Kleist

I have considered under belly skins, but one problem that I forsee with them is moisture accumulation (and road gunk). Sidewalls would keep air from going under the bus, but would not accumulate any moisture.

Actually, I was thinking that a smooth belly pan would actually preserve the underside atleast on a pusher where you could extend the skin all the way up to the front of the bus.

I would construct it by laying 3/4 plywood across between the frame rails. This way you could make that considerable area a storage basement that was accessible from inside the bus. It should also provide sound and temp insulation. I would then skin over the plywood with sheet metal and paint the hell out of it.

Is there any decent bus underside pics/drawings anywhere on the board?

[the_experience03]

you're not going to be able to make it very air tight I don't think just due to the flexing of the body and stuff so it might be best to allow it to have some airflow. The frame on my truck, for instance, is fully boxed and even has a diagonal gusset internally in the front ( so it kinda looks like this [\] if you cut it open) but even the frame has actual breather holes.

I would be left wondering if the decrease in drag wouldn't just be offset by the weight. I think a good front air dam, some side skirts, and maybe one of those spoilers for the rear (which also helps keep the rear windows clean) would probably give you the same benefits and would be a lot easier. The side skirts would even help cover those unsightly battery compartments and water tanks that inevitably hang lower than the stock skirt.

[captainkf]

Here is a phot of a bus that has had the skirt lowered.

http://www.skoolie.net/gallery2/v/Skooli ... 1.jpg.html

-Richard

[Eric von Kleist]

Instead of a spoiler, how about rounding off the rear end? I think that would work better (could be wrong). If you could just round off the rear end until it was half as wide as the end of the bus, you could probably get another 10%+ on mileage.

This was my original plan with the Jeep, but I never got around to building the rear end. If you look at some of those car hauling semis on the road, the ones with the fabric sides, you will see a fiberglass cap on the rear end that helps to streamline the vehicle. This is very effective. Maybe not extremely practical from the stand point of access to the rear door, but very effective.

Funny thing is, I had the idea for those fiberglass caps about 30 years ago. Glad to see that my idea was not just useless speculation...oh, wait, I never did anything with it...I guess it was useless speculation!

[pete c]

Yeah, flex would be a concern, but, if you overlap the skins kind of like roof shingles, I think it would work, would keep the weather out and allow enough rbeathing to keep things inside dry. You just couldn't do high speed runs in reverse particularly in wet weather. I think this is a reasonable design restraint.

[the_experience03]

Originally Posted by pete c

You just couldn't do high speed runs in reverse particularly in wet weather. I think this is a reasonable design restraint.

[lapeer20m]

wanna save money on fuel??? don't drive your bus....lol

i'm j/k

be interesting to see how things work out.

i haven't even started my bus since jan 1st. My block heater doesn't work and temps have been hovering right around zero degrees. i have confidence she would start, but not without a battery charger or jumper cables. Even with my almost new 8D battery.

[Griff]

Originally Posted by captainkf

Here is a phot of a bus that has had the skirt lowered.
http://www.skoolie.net/gallery2/v/Skooli ... 1.jpg.html. . .

When I tried the link, I got this:
Error
Error (ERROR_MISSING_OBJECT) :
in modules/core/classes/helpers/GalleryFileSystemEntityHelper_simple.class at line 119 (gallerycoreapi::error)
in modules/core/classes/GalleryCoreApi.class at line 1942 (galleryfilesystementityhelper_simple::fetchchildi dbypathcomponent)
in modules/core/classes/helpers/GalleryFileSystemEntityHelper_simple.class at line 64 (gallerycoreapi::fetchchildidbypathcomponent)
in modules/core/classes/GalleryCoreApi.class at line 1885 (galleryfilesystementityhelper_simple::fetchitemid bypath)
in modules/rewrite/classes/RewriteSimpleHelper.class at line 50 (gallerycoreapi::fetchitemidbypath)
in ??? at line 0 (rewritesimplehelper::loaditemidfrompath)
in modules/rewrite/classes/RewriteUrlGenerator.class at line 98
in modules/rewrite/classes/parsers/modrewrite/ModRewriteUrlGenerator.class at line 50 (modrewriteurlgenerator::_onload)
in init.inc at line 113 (modrewriteurlgenerator::init)
in main.php at line 73

What color do I use for which number? (Man, I haven't done a color-by-number picture in quite a while. . .hope I can stay in the lines. . .)

[pete c]

Originally Posted by Eric von Kleist

Instead of a spoiler, how about rounding off the rear end? I think that would work better (could be wrong). If you could just round off the rear end until it was half as wide as the end of the bus, you could probably get another 10%+ on mileage.

This was my original plan with the Jeep, but I never got around to building the rear end. If you look at some of those car hauling semis on the road, the ones with the fabric sides, you will see a fiberglass cap on the rear end that helps to streamline the vehicle. This is very effective. Maybe not extremely practical from the stand point of access to the rear door, but very effective.

Funny thing is, I had the idea for those fiberglass caps about 30 years ago. Glad to see that my idea was not just useless speculation...oh, wait, I never did anything with it...I guess it was useless speculation!

I've thought about this as well. You could make horizontal cuts in the sides at the floor and roof and bend it inboard for kind of a boat tail look. I would leave the existing floor for and bumper to form cool looking horizontal stabilizers.

This might give you a fraction of a mpg and give up valuable living space, but, you'd surely have the only boattail speedster skoolie on the block.

[captainkf]

http://www.skoolie.net/gallery2/v/Skooli ... 1.jpg.html

Let's try this.


-Richard

[pete c]

kinda makes it look like a city bus.

[Ryan Grimm]

Eric Von Kleist, I think the rounded tails on those fabric-sided trailers are there to relieve vacuum that forms when the truck passes through the air: otherwise the fabric would tend to balloon out and rip off/flap in the breeze....dunno if I'm right, but it's my delusion and I'm stickin' to it!

I'm waiting for the local rock crushing company to let me know when they replace their conveyor belting....they said I can have up to 300 feet of it when it comes off. Normally they have to pay to dispose of it.....
The fact that it's flat black would look cool on my pickup (test bed), and if it works it's going on my future rig.
And I can always touch up the color with black rubber paint if need be.

[oldog12]

I'm waiting for the local rock crushing company to let me know when they replace their conveyor belting..

Save me a 10' hunk

[crazycal]

A couple of things to think about. When I was a wee tot(17 to be exact), I worked as a gopher at a garage the specialized in Ferraris. One of the things that I noticed(besides the fact that the owner was a dope smoking A-hole) was that the newer cars had the under bellies sheeted with metal panels to make the car smooth from the front to back. Obviously not where the suspension was. I asked one of their top mechanics why that was. He told me that it helped the air pass under the car with less turbulence which meant less drag. When you worked on something from underneath, you unbolted the panel and had access to what you were working on. A 308 (besides being a very good rifle cartridge) had a 3.0L 8 cylinder that had a top end of about 140mph. I also saw one 208gt(2.0L 8 cylinder) that was a grey market car(made for european market) that was just as fast. By today's standards, those speeds aren't that impressive. But this was the late 1970's. I'll bet that many of today's cars are designed the same way.

Another thing that I noticed(sometimes I amaze even myself with how observant I am) when I was coming back from AZ to CA in my new bad boy. I was traveling pretty slow, 55 to be exact on I5 that has a speed limit of 70. I think some of the truckers were pissed off that they had to pass me. About a half dozen times, a semi would pull to about 20 feet of my back end, then change lanes to pass me. This seemed to slow me down just a little bit. It might have been my imagination(we won't talk about that), but I think they were doing it on purpose. They might have been NASCAR fans. Does anyone remember Rolling Thunder when they were talking about drafting.

The other subject that was brought up was the auto transporters that had the rounded caps on the back. I read that the rounded edge provides a smoother transition for the air at the back of the truck decreasing the vacuum effect. I have also seen trucks with these pillow type things(I know, my technical terminology is overwhelming for some) that get pulled out as the truck goes faster down the freeway. I read that this gave an increase in fuel economy. I don't remember how much.

So, I'll bet you are wondering what this idiot is rambling on about. Well, Im wondering too, because I lost my train of thought. Oh, now I remember. I think that any turbulence that can be eliminated from the bus will help lower drag and increase fuel economy. That is in the front, underneath, sides and back. I think the underneath and back being most important.

That my story and I'm sticking to it!

[boojiewoojie]

I ain't no engeneer, but I used to work for a homebuilt airplane company (Lancair) and they obsessed over the trailing edges of the plane. I'd say the most important drag improvement is to make less space between pavement and bus and decrease the sucking noise coming off the back end of the bus. I'm thinking about some kind of wing on the back or rounding the back off a little w/ fiberglass. I definately want to lower the bottom and mold an air dam at the front. There's plenty of clearance to at least bring the front down to the same level as the door. I have some storage bays underneath and I'm thinking that maybe I should skin the whole bottom. Of course I'll have to figure out how to get to everything etc. Even a 1mpg improvement would pay for itself on one trip w/ today's fuel prices.
Rick

[lapeer20m]

one thing i like about my skoolie is it's rugged off-road-ability compared to stick and staple rv's. Curbs, ditches, fields, ect are all things a skoolie without a skirt can tackle. Watch out for the ocean though! The sand can really suck the life out of ya! .....or so i've heard!

I guess good fuel economy might be worth giving up off-road-ability. depends what you do with your bus.

[oldog12]

... Maybe put one of those bubbles on the rear so it could be lifted like a canopy when you're not driving?...

[boojiewoojie]

Yeah, definately a comprimise. 'Course I haven't even taken my seats out yet so I'm just kind of dreaming right now anyway. We plan on traveling backroads so I'm not too worried about clearance. I do want to keep the front and rear angles decent so we don't scrape excessively.