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Old 09-03-2014, 05:39 PM   #111
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Re: The Broccoli Bus

Based on thjakits's suggestion,

viewtopic.php?f=9&t=467654&start=30#p591056

I started looking at kamm airfoils and decided it would be pretty easy to stick a kamm foil on the rear end of a brick, er, I mean, bus.

You can't see it from the photos, but the last about 5 feet of the roof taper down by approximately 3 inches to give a shape approximating the kamm end foil.

It seems like all the hypermilage kids are taping cardboard onto the butts of their cars, and you see those semi trucks with the crazy unfolding tail thing, so I figured I could build something in there that looked OK and sort of served a purpose.

I think on a car, a kammback instantly gives the vehicle a shape that, stylistically, looks dated or weird. On the bus it seems OK to me.

Take a look at some visual examples here:
https://www.google.com/search?q=kamm+ba ... r&tbm=isch

In the end, the sharp hood over the end is more about keeping water and rain off the end of the bus than anything else, and visually I think it looks better than the rounded endcap.

Quote:
Originally Posted by crazycal
I think your bus looks awesome but I have one question about the back cap. Do you think having it straight with sharp edges will hurt mileage?
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Old 09-03-2014, 07:55 PM   #112
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Re: The Broccoli Bus

...up that high the sharp edges should not be a safety problem.
In any case you always can make the edge blunt - Kamm design will work as long as the air gets a clean break from the surface - so the edge of the upper rear end cap has to be as sharp as you dare...
The basic idea is, that the air leaves the rear edge without a chance to "follow" the surface. Rounded edges ALWAYS drag some of the air around the edge curve (koanda effect) and finally create turbulence.
The soft downwards curve of cars at the rear is just a design compromise - Kamm didn't care if it goes straight back or slightly down (...it seems the max angle you can curve down is 11 - after that air would become turbulent (as opposed to laminar flow) and create more drag.

There is plenty of reading and looking and studying on the net, regarding vehicle aerodynamics - you wouldn't believe how much difference it makes to point the exhaust correctly - from actually getting some thrust from it, ....or at least zero drag, to acting like a bloody parachute - straight up stacks are a big aerodynamic no-no!
Then - how often do you go at full speed and for how long? Not likely that any of the buses on here do even 1% of the average Long-hauler distances.....

Also, IF you plan to put anything on the roof - solar panels, roof deck, water tank, roof cargo pod, etc, ...your airflow is turbulent LOOOOONG before it ever hits the rear cap!
However - looking that sharp, I'd stick a few vortex generators on it, just 'cause!!
[But don't use the huge ones that are used to streamline long-haulers, too big and ugly!!]

Cheers,

thjakits
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Old 09-04-2014, 11:33 PM   #113
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Re: The Broccoli Bus

Just pounding in the rivets...

Takes longer when there is a left and right side.
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Old 09-05-2014, 03:46 PM   #114
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Re: The Broccoli Bus

When it came time to remove our floor on the 1996 Bluebird All American we found the best tools to be a 5 foot straight bar like landscapers use and a 4 foot wrecking bar with a nail puller on one end.
I would use the long bar and the wife the short one. I would slide the long bar under the plywood and she would slip in the shorter bar to hold the floor up while I pushed the long bar in deeper and we lifted
the plywood up off of the nails that they used to hold the flooring down. When we got the plywood up the long wrecking bar was used to pull the nails which pinged off of the ceiling when they came out of the floor. Nails that wouldn't extract that way we would pound side to side to widen the hole in the floor sufficiently to release the nail. Also have you checked out Airtabs for further streamlining on your bus? I was toying with the idea of using some conveyor belt bolted to the from bumper for a makeshift airdam since 50% of air drag is created from air hitting the under carriage.
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Old 09-05-2014, 06:08 PM   #115
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Re: The Broccoli Bus

...who is doing the bucking bar?

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Old 09-05-2014, 07:23 PM   #116
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Re: The Broccoli Bus

You might want to check on the BCM bus forum before you add air dams under your bus. There are several discussions of the topic over there. Depending on where your radiator gets its cool air from, an additional air dam may mess up the factory cooling. My bus has a front engine with the radiator in the conventional location. There is a factory installed dam between the frame rails and directly under the radiator. This set up produces high pressure in front of the radiator and low pressure behind it thereby forcing air through the radiator (and doing whatever else it might be good for). My two cents worth.
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Old 09-05-2014, 07:44 PM   #117
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Re: The Broccoli Bus

.....YOU - want to play with airdams, cold air intakes, SITING LOW/HIGH pressure areas on your vehicle??

http://www.autospeed.com/cms/search/ind ... 21&x=0&y=0

WARNING! THIS SITE IS ABSOLUTELY ADDICTING!



YOU HAVE BEEN WARNED!!

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Old 09-05-2014, 07:49 PM   #118
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Re: The Broccoli Bus

http://www.autospeed.com/cms/article.html?&A=2159

http://www.autospeed.com/A_2160/cms/article.html

http://www.autospeed.com/cms/article.html?&A=2162

OBVIOUSLY all car stuff - but the how-to, theory, practical application is just the same for the buss - just BIGGER!

....especially if you have RE cooling problems - try to figure out the airflow in the "engine room" ....


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Old 09-05-2014, 09:48 PM   #119
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Re: The Broccoli Bus

A friend of a friend who is studying to work in aerospace, (Boeing) installing rivets. How lucky am I?


Quote:
Originally Posted by thjakits
...who is doing the bucking bar?

thjakits
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Old 09-05-2014, 09:52 PM   #120
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Re: The Broccoli Bus

Fun fact for some (all?) of you who own a front-engine bus on an International chassis and possibly others:
Have you noticed where the air intake is on the hood/cowling? It's right below the front windshield with the opening facing the windshield. Why? Because the windshield creates a high pressure area which helps push air into the engine! Or so I've read, anyhow.
Now that's clever use of poor aerodynamics...
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