1973 dodge motorhome areo

[seuadr]

take a look at this thing!







evidentially designed by Larry Shinoda - i guess he had an outside firm and this was an attempt at an efficient design, allegedly wind tunnel tested.

kinda interesting.

one popped up on my facebook marketplace search, so i looked into them, having never come across this.

kinda homely, but, considerably more aero and handsome than most of the other motorhomes from the early 70s

[seuadr]

i found that while looking for something like this:





late 70's early 80's transvans - fiberglass shells and kinda a bit aerodynamic at least. i've seen several of them around here gutted for projects and then the owners lost interest and are selling them cheap (looking pretty hard at one for 500 right now...)



maybe maybe?

the one i'm currently looking at has a 318, and is a 79, which means it has either a 3 or 4 speed no OD trans - that is problematic.. but newer, hydraulically actuated 4 and 5 speed OD trans that will bolt up are out there, and, a 318 carb to EFI conversion with a stand alone controller can be done for ~700 dollars.

got me thinking...

i've been reading on diffusers vs pans for the underside, and it seems like an either/or proposition - so if i were to make up a front and rear diffuser for the above, i wouldn't also need to worry about a pan or visa/versa?

i presume that a boat tail or offset box would still give me benefits as well even though the back appears to need to be a little more sloped to fit inside the template better?

[Piotrsko]

Well a 79 should have a spreadbore thermoquad carb which if it hasn't been backfired on can be modded to be really frugal. Will have a 3 speed 727 auto which will accept a lock up TC but isn't stellar otherwise

[freebeard]

That spare tire and rear door remind me of my Clark Cortez.

If that body is fiberglass {or not] one could make 2ft-long pie cuts on the back and taper it down to the door height. Maybe turn the spare and put a pocket in the back wall?

[seuadr]

Originally Posted by freebeard

That spare tire and rear door remind me of my Clark Cortez.

If that body is fiberglass {or not] one could make 2ft-long pie cuts on the back and taper it down to the door height. Maybe turn the spare and put a pocket in the back wall?

Now that is an interesting idea.. i saw one that was 30 ft but dont want one that long, but could shorten it and maybe boat tail it a bit at the same time...

[aerohead]

Originally Posted by seuadr

i found that while looking for something like this:





late 70's early 80's transvans - fiberglass shells and kinda a bit aerodynamic at least. i've seen several of them around here gutted for projects and then the owners lost interest and are selling them cheap (looking pretty hard at one for 500 right now...)



maybe maybe?

the one i'm currently looking at has a 318, and is a 79, which means it has either a 3 or 4 speed no OD trans - that is problematic.. but newer, hydraulically actuated 4 and 5 speed OD trans that will bolt up are out there, and, a 318 carb to EFI conversion with a stand alone controller can be done for ~700 dollars.


got me thinking...

i've been reading on diffusers vs pans for the underside, and it seems like an either/or proposition - so if i were to make up a front and rear diffuser for the above, i wouldn't also need to worry about a pan or visa/versa?

i presume that a boat tail or offset box would still give me benefits as well even though the back appears to need to be a little more sloped to fit inside the template better?

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For a motorhome, I'd use something other than the 'template' as a guide.
The 'template' is for a 'wide' vehicle, compared to its height.
The MH is 'narrow' compared to its height, and it's more proper to use the width to define the aft-body shape.
Length for length:
1) an all-compound-curve boat-tail will return the lowest Cd.
2) 1st runner-up is a simple 'curved-panel' boat-tail, with edge radii, but no compound surfaces.
3) 2nd runner-up would be the simple, curved-panel boat-tail, with zero-edge radii.
4) 3rd would be a straight, fixed-angle boat-tail, with edge radii.
5) 4th, a straight, fixed-angle boat-tail, without any radii.
6) 5th, a box-cavity.
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* The 'ideal' is going to be 'long' and like the tail-car on Samuel Calthrop's 'Air Resisting Train', of 1865.
* Tietjens & Ripley's WESTINGHOUSE aerodynamic self-propelled railcar, Cd 0.08, 1932.
* Next to that would be Fachsenfeld's mid-1930s extensible tail, Figure 8.64, in Wolf Hucho's 2nd-Edition Aerodynamics of Road Vehicles.
* Followed by Walter Korrf's semi-trailer, SAE Paper # 649B, January, 1963.
* R.B. Potter's US Patent # 2,737,411, March 6, 1956.
* NASA's Project Shoebox, Ford Econoline.NASA Photo: E-38096, 1981, NASA Dryden Research Center Photo Collection.
* Thomas Scott Breidenbach's US Patent# 8590961, February 21, 2012.
* Bearman et al., modified Ahmed body
* Continuum Dynamics box-cavity.
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A decision will have to be made about a target Cd and your choice of 'design', as it will heavily impact the complexity of fabrication.

[seuadr]

Originally Posted by aerohead

A decision will have to be made about a target Cd and your choice of 'design', as it will heavily impact the complexity of fabrication.

so - that is a really good point - i have no idea what target Cd i want, much less what i currently have (well, i don't have anything .. yet.. but when i do..)

Now, the stock B300 is 79 inches wide by 80 inches tall exterior, the interior cargo height is 54 inches. the height of the camper is between 66 and 70 inches reportedly (i've seen people report anywhere from 5ft 6" to 5 ft 10" but most seem to settle right around 5ft 8") so it is ~16 inches taller than wide at the front. I haven't found any info about how much wider it is, but i've seen several with queen mattresses in the back and they go wall to wall supporting that it is at least 86" (i'm taking a swag at ~3" either side interior to exterior at a bare minimum.

given how the mirrors look in relation to the sides, i'd take another swag at it is probably at least 12" wider than that, lets call it 8ft 4" wide for giggles.

i can't find any info on frontal dimensions so getting an idea of drag is going to delayed until i have one i can physically inspect i fear.

still, i think that there appears to be significant opportunity anyhow.

[aerohead]

Originally Posted by seuadr

so - that is a really good point - i have no idea what target Cd i want, much less what i currently have (well, i don't have anything .. yet.. but when i do..)

Now, the stock B300 is 79 inches wide by 80 inches tall exterior, the interior cargo height is 54 inches. the height of the camper is between 66 and 70 inches reportedly (i've seen people report anywhere from 5ft 6" to 5 ft 10" but most seem to settle right around 5ft 8") so it is ~16 inches taller than wide at the front. I haven't found any info about how much wider it is, but i've seen several with queen mattresses in the back and they go wall to wall supporting that it is at least 86" (i'm taking a swag at ~3" either side interior to exterior at a bare minimum.

given how the mirrors look in relation to the sides, i'd take another swag at it is probably at least 12" wider than that, lets call it 8ft 4" wide for giggles.

i can't find any info on frontal dimensions so getting an idea of drag is going to delayed until i have one i can physically inspect i fear.

still, i think that there appears to be significant opportunity anyhow.

I agree. Quite a bit of low-hanging fruit and a number of vehicles we can be inspired by.
Drag is a direct function of wake area.
And there are a number of areas that can be cleaned up before we ever get to the trailing edges.

[freebeard]

I agree. Quite a bit of low-hanging fruit and a number of vehicles we can be inspired by.

Recycling an old pic incase you haven't seen it.

Drag is a direct function of wake area.

Strike an arc from the windshield to the aft end to just clear the van body. It could carry a favorable pressure gradient further back to counter the increase in frontal area, and give a nice opportunity for skylighting and &.

Ogive curves added to the front edges of the van body.

edit: The picture was embarrasing, so I took it to the GIMP. The result is embarrassing, I can't seem to resize the Smudge tooll.

[seuadr]

Originally Posted by freebeard

Recycling an old pic incase you haven't seen it.





Strike an arc from the windshield to the aft end to just clear the van body. It could carry a favorable pressure gradient further back to counter the increase in frontal area, and give a nice opportunity for skylighting and &.

Ogive curves added to the front edges of the van body.

edit: The picture was embarrassing, so I took it to the GIMP. The result is embarrassing, I can't seem to resize the Smudge tooll.

i like it!

i was thinking something similar for the mirrors or even possibly replacing them with cameras - i already have them for my current travel trailer.

i actually might be able to get a photogrammetry scan of the vehicle after i get one - the university i work for has equipment like that and might let me check it out.. i may also have access to software to model it as well as fluid dynamic modeling software (and there are some free options out there for both..)