New and seeking aero advice for my "brick"

[freebeard]

Anyway thanks all for the ideas & suggestions but I'm trying to get an idea of my cost and effort for reward ratio. Is there a site to help me compare different modifications and what the energy savings would be? I'm sure I could spend $10G making it look like a rocket but I'm not going to do that. Im trying to find that sweet spot in the ratio (effort<=reward) and what to expect.

That would be Ecomodder. It's all anecdotal, because each owner and use case is different, but there are accepted principles based on both hearsay and evidence.

Question: If I have a square meter box, what is the aerodynamic reduction of force required to push that through air at 60mph if I instead it had a 45 degree leading edge? Is this an applicable question for the front box of the truck?

Every element has a Cd. Those are both summed and interactive.

If that greenshield thing works, maybe I could mimic the idea and use it to hide my spare up there. Reasonable?

It needs to be moved forward over the cab to maximize the length of roof behind it. Davits for storing and retrieving the spare? That's the style with [the decidedly unaerodynamic] Dekotora trucks. They started out as a place to store tire chains, etc. Colani's trucks use a tilted oblate spheroid:


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

Here is a sketch I did for another thread, some of it might transfer to your case. Half-round front corners and a deflector ring at the rear.



Rear-view mirrors are also impotant.

I just discovered the archive view of the Aerodynamics sub-forum. Scan this list for item of interest:

https://ecomodder.com/forum/archive/f-6.html

Here's a list of relevant threads from here.


https://ecomodder.com/forum/showthre...uck-34674.html

[kach22i]

Originally Posted by Farraider

Anyway thanks all for the ideas & suggestions but I'm trying to get an idea of my cost and effort for reward ratio. Is there a site to help me compare different modifications and what the energy savings would be?

1. How much can you get for your vehicle today? It would make a great work truck for a builder.

2. I so much more favor a Diesel Sprinter as your starting point as myself and others have been leading to towards.

Will you ever get it this nice?

Winnebago
https://winnebagoind.com/products/cl...avato/overview

Travato

Class B Starting at: $111,645*
View Model

No, but it can be a nicer end product with less effort and money than if you start with your ambulance.

2006 Dodge Sprinter - $7200 Diesel 5 cylinder
https://seattle.craigslist.org/see/c...717993528.html

Selling my 2005 Sprinter van. Strong engine and transmission. No leaks. Good tires.
I'm second owner. Clean title. 250k miles. Super efficient - 21 MPG.

2013 Mercedes Sprinter Bluetech Long-wheel base One owner - $1 (NE Couch st)
https://portland.craigslist.org/mlt/...713535697.html

Hello, Im selling my 2013 177" extended wheel base sprinter van. This van is in great shape and has never let me down. It has 231,624 miles all of those miles are strictly freeway miles as I drive to Missouri very often. The inside of the van is already insulated and upholstered. The van holds a clean title as it has never been in any kind of accident. The check engine light is on, and I have been told by a mechanic that it is the DEF system which I never had the time to repair and was quoted $1000 to fix it. I am the original owner from 2013 and have taken care of it very well.
WINDSHIELD HAS BEEN REPLACED.

06 sprinter van high top short model runs perfect very reliable 24mpg - $4900 (Turbo diesel 5 cylinder Marysville)
https://seattle.craigslist.org/sno/c...710593951.html

odometer: 396,708

Oh my God, 400,000 miles................dang, those other ones at 250k are just babies.

What a mule that thing is, in a good way.



The artwork I would do for one of these Diesel Sprinters would be far less involving, that much alone tells you what a superior starting point they are.

The 8-point list would be down to less than half.

Chin spoiler, rear box cavity baffles and pizza pan wheel covers with zip ties - DONE!

[euromodder]

Welcome !

Originally Posted by Farraider

Hi Everyone,
I have a camper I built from a 1994 square-box-style ambulance. It has a 7.3 IDI diesel and get about 13mpg at 55mph

Never going to return great mileage with a huge engine and boxy bodywork.

Do you plan on doing many miles /year ?
That'll mean wether the improvements have any true value (saved fuel minus your investment)

Driving 5mph slower may be an option.

It has a huge flat front area that just grabs the wind and I keep thinking about putting something up there to make it more aerodynamic.

Air dam underneath up front

Sideskirts

Cover the rear wheel arc

Wheel hub caps

Close the gap between cab and box, if any, including underneath.

Bigger / wider & higher deflector on the roof of the cab.

Bigger radius on the corners of the box
(by adding a half-pipe - can be used to store long thin items)
or
turning vanes on the corners



Rounding the rear corners too much, will decrease stability though
(google coanda effect

You would need something like this to reduce drag aft:




Lighter color than black will keep it cooler

[kach22i]

Originally Posted by euromodder

Welcome !

Never going to return great mileage with a huge engine and boxy bodywork.

Do you plan on doing many miles /year ?
That'll mean wether the improvements have any true value (saved fuel minus your investment)

Driving 5mph slower may be an option............

Good points and nice graphics euromodder.

There are nice camping sites on a lake less than 30 minutes from my house, in that situation this ex-ambulance would be just fine.

Then again I could drive half a day and still be in Michigan and on a really big lake, some would call it a Great Lake. In that situation something with better MPG would be nice.

Farraider , could you share some more details?

It's going to come down to some simple math.

[euromodder]

Originally Posted by Frank Lee

Why add the frontal area?

If it manages to reduce the drag coefficient more than it increases area, it works ...

Thos bumps are found on small European vans, busses seen above, trains, ...

Don-Bur trailers work
Despite the added area - c an't reduce internal trailer height
Aerodynamic Teardrop Trailer

[kach22i]

Originally Posted by euromodder

If it manages to reduce the drag coefficient more than it increases area, it works ...

Thos bumps are found on small European vans, busses seen above, trains, ...

Don-Bur trailers work
Despite the added area - c an't reduce internal trailer height
Aerodynamic Teardrop Trailer

There is a simple diagram from the late 1970's (I presume) that I find once in a while on the Internet. It shows a boxy sedan with a 90 degree angle between radiator and hood and some rotational arrows illustrating turbulence at the plane change. This is not a real life condition found in the last 30 years on vehicle design but even back then I suspect it was a misrepresentation because the high pressure wave in front of the vehicle directs air flow just above it up and over the hood.

I think you are right that it comes down to in field or in lab testing of individual conditions, and no two will be the same.

In the link below "radius of curvature of a fairing sitting on top of the caravan" seems to be an important element in the CFD studies. maybe there is something in the article that sheds light on our related topic.


Posted By LEAP CFD Team on Jun 21, 2017 | 0 comments
https://www.computationalfluiddynami...l-consumption/

The Findings

The most dominant factor that contributes to drag and fuel consumption on a caravan is the speed at which it is driven. This follows from basic aerodynamics theory which states that the drag goes up four-fold, for a two-fold increase in speed. Put another way, the drag you experience at 30kmph is a quarter of the drag that hits you at 60kmph. So unfortunately, speed will eat into your fuel economy and holiday budget.

The Don-Bur Aerodynamic Teardrop™
Aerodynamic Teardrop Trailer



Of course there can be other problems with going higher, like not fitting into your garage, or worse.

http://forums.pelicanparts.com/off-t...pics-4597.html

[kach22i]

I passed a similar ambulance on the highway yesterday, dang those things are wide.

I can see the attraction of starting with a wider box than a Sprinter type van.

One thing a bit unclear to me, is the former ambulance already outfitted as a camper?

I can see why you would want to hang on to it if already made into a camper.

[Farraider]

Originally Posted by kach22i

I passed a similar ambulance on the highway yesterday, dang those things are wide.

I can see the attraction of starting with a wider box than a Sprinter type van.

One thing a bit unclear to me, is the former ambulance already outfitted as a camper?

I can see why you would want to hang on to it if already made into a camper.

Hi Guys,
Yes it's already a camper and we drive it down and around Mexico in the winter to escape the snow/cold and go rock climbing, eat cheap tacos and soak up some sun. Probably 10-15K mi/yr.

Regarding Sprinters, they're too common and have no character IMO - I like this vehicle and I did all the work myself.


I just seem to be making the aero worse. Today I installed a hitch on it so I can also carry my dual sport bike down this year too. There's an extra 400lbs to carry. Ugghhhh. Maybe that will encourage me to take the "5mph slower" advice.

Euromodder, your suggestion about rounding the corners more with half pipe. Half a 6 or 8 inch pvc pipe just mounted down the corners? With middle of the curve directly over the corner? I wonder how much that would help? It probably pales in comparison to fixing that huge flat front and rear drag.

Thoughts?

[kach22i]

Then get started.

If you just want to get your feet wet, the conveyor belt chin spoiler is a weekend project if you get all your supplies together the weekend before. There is a link in my signature for some tips on how to do this. Lawn edging is fine for a year or two or until someone backs into it with their bumper and should be considered temporary.

The roof deflector fairing is at least a two week project unless you can repurpose a found item and make do.

The most beneficial item is the longest most time consuming and challenging, the rear box cavity as it may have moving parts. Maybe there is something on the market already or a damaged semi-truck unit from a junk yard can be modified. Point is, it's just big and requires some engineering.

I would proceed in the order above and knock out the other items along the way.

[freebeard]

Take a look at this picture from Permalink #4



The dust in the air shows your areas of concern. The dust suspended abaft the top edge is heavier than the sides because the step is 2-3ft instead of 6-8". The dust over the cab is similar to the cap you have already.

I'd make a bullnose cap that extends above the windshield as a visor. I'd also make it clamshell open reverse-alligator style to make a roof-top tent, but that is optional.

For the sides, what is the dimension of the front face of the van, the depth of the door pillar and the distance from the van edge to the opened door's edge?

In the rear, would a box cavity (Trailer tail™) enclose the sport bike?