Quote:
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? |
--------------------------------------------------------------------------------------
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.
----------------------------------------------------------------------------------
* 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.
--------------------------------------------------------------------------------------
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.