rear bumper delete and removable boat tail filler panel 2 ideas to merge

[gumby79]

Eg of tarped load.




Ideal would have been to fill the gap from underneaththe tarp to tuch the tail finn instead of 4'from the rear. Some glad bags will help with thisin the future, as it was this was the maiden voyage for cap and this is what I got.



What angle on the gate(absolute angle to level)?

I may go as simple as a simple I.M.C.A. stile 2"×.125 tube . Bumper .Insted of a hand built role pan, to cover the hitch.


Airfoil could be flat. Purpose for airfoil is to streamline the 4.5"sq ×1/4" hitch cross tube. It would be nice if the tail of the Airfoil was positioned to be a step when the gate is closed/open like the current step bumper

Easy to clean snow bugers is a design requirement , they can over load a 1ton truck from a bad design.

[kach22i]

As a guy with a pickup truck which backed into a pole because my passenger was distracting me by throwing his arms around wildly and yelling/laughing like a maniac (I have some "fringe" friends), and as a guy which was just sitting there at a stop light when the idiot behind me thought the light had changed and crushed my rear bumper a second time - keep the rear bumper intact.

Do you have a belly pan or something which would begin to warrant removing the rear bumper?

I can see cutting slits or drilling holes in the rear bumper to relieve air pressure, but doubt you have anything resembling clean air flow under the truck.

[gumby79]

Agreed safty first the

I.M.C.A. stile 2"×.125 tube . Bumper. Insted of a hand built role pan, to cover the hitch.

,not in drawing ,should have about the same crash strength as the stock + more crush zone distance
If i get hit or I back into something hard enough to get through the I.M.C.A. Modified bumper , then the stock bumper would have done body damage by folding into the body as the side sections are just chromed sheet metal ~ .090" thick maby as low as .065" with a center section (frame wide)of .250" flat plate for the bumper mount hitch ball.

Ill fix the broken link to the pic of I.MC.A Modified rear bumper.

[Xist]

I have often thought a foot of six- or eight-inch-thick foam board would make a great back bumper.

Or a boat tail!

I would feel safer with a better bumper up front, too, it would just do little aerodynamic good. It seems like I keep seeing cars that do not have bumpers, just a big rounded front.

[aerohead]

unless the panel goes all the way down to the bottom of the belly there will be a pressure discontinuity 'kink' as Hucho calls it,which will compromise the drag reduction.
The wing may be in a stalled area of turbulence and not be able to divert any flow.A nearly-full belly pan might be required to clean up the flow enough for a wing to work down there.

Pickups have some of the highest drag underbodies

If it did,Hucho says that it will cause more harm than good,due to the drag of the wing itself.He tested a lot of aero accessories while at the VW wind tunnel and never saw any sort of flow diverter improve drag.

[gumby79]

If im understanding correctly the 5 sided box that sticks out 3"per side and a brick shaped hitch cross member is the best cleanup I can expect.
Ive heard sence I was a kid that a rollpan bumper with a hidden hitch was about the best aerodynamic package you can do to a pickup. Nowdays its airdams , side skirts, aero caps,and belly pans and many more on top of the tryed and true Rollpan . Iam merely trying to tie it all together and figure out a long term plan.

I have a tendency to dream big. Some times to big.
So for this level of mod some extra steps are needed.
1 full belly pan
2 side skirts
I alluded to side skirts by asking for advice on width "hitch wide or out to side skirts as rear mount" under "Request for Advice #4"in drawing picture.
3 ??? What else keep them coming this is another high-school idea like the cap its purpose and design have adjusted to changing life ... I cannot see all the shortcomings but I can adjust to the ones that are visible to me or others. Eg I saw that the supper aggressive Airfoil could be to much and said it could be flat if nothing mote than a pice of sheet metal pop rivited as a tail cone...

Airfoil could be flat. Purpose for airfoil is to streamline the 4.5"sq ×1/4" hitch cross tube.

Corection the hitch is 38"w 2.75×2.75 sq. It hangs 13"lower than the lowest sheet metal and 17below the bottom of the bed over a foot off the ground.

----
---- how about part 2 idea #1
Boat tail patch panel to allow the tailgate to be set at ??°as a rear diffuser . The gate idea would work better minus the the giant hallow ,parachute 5 sided air scoop they called a bumper in the 90's and a rearbelly pan from the rear end. I have a 4 ×8 sheet of plexiglass from an old sign to work with just trying to think of a best use of it but mixing a 4th consept in I felt was too long a title blending 2-3 into one build is complex enough .
I like the suggestions so far it just increased the #of concepts
The center belly pan should be simple slap a flat panel to the bottom of the running bords with dutz aircraft fasteners into the cross stringers . add the missing section between the cab and rear wheels wala a belly to the rearend. Corce have to accommodate the drive shaft . This is what we had to do to our street stock with a custom floor pan also make room fore 2 6"×36" glasspacks. All with in the scope of my toolbox of understanding and skills my shapes are dreived by eye not computer programs so my thinking is a little different but we can communicate (as long as you can figure out the Cypher)sorry bad spelling and composition but I do try.
Gumby Stay Flexible

[kach22i]

I'm going to try my had at being an unimaginative pragmatist here, so bear with me.

Take that long list of yours and toss it out, nothing is going to be as effective as lowering the "A" in the CdA formula.

As with any type of pickup truck cover, you have already compromised the utility of the vehicle, frequent large heavy loads are not a daily routine to say the least, right?

Lowering the truck depletes it of most it's cargo holding capacity, but it is the simplest route in my opinion.

Below is a truck I've seen recently, I forgot to ask him about his MPG, we talked mostly about Eastwood rust preventive products having a marginal effect.

2016 Misc by George Kachadoorian | Photobucket






Just food for thought.

I'm sure the baby moons and tiny sport mirrors help a bit.

Perhaps go one step further and seal off the gap between the cab and bed?

[gumby79]

I hope I haven't offended
2
Agreed reduction of A is a large gain. in this old dodges case loss will occur apon repars being made . Ill explain . This model of dodge uses an aproxamitly 3" tall 0 rete spring rubber for proper ride hight. Theas last (from what I've read) aproxamitly 100,000 mi 10-15 years. My truck on the original rubbers @275,000 and 25years the rubber is about as thick as a pice of paper. = ~ 3"lowerd in the front. Stock rear /~ 17" under the hitch. So whin i get this defect repaired the A will grow.

If the Montana roads and 4-8"ice ruts hadn't taken out 3 Ball joints in 6 months, I would not be considering raising the front end. Cause and effect. I think the Ball joints are operating out side an accepted operating angle causing failure.at a price of $100.00 ea upper and 75.00usd ea lower purchased yesterday will in stall in near future. With theas NASCAR spring rubber less the splits ABA testing will be labor intensive but valid. I will have to do a life span test to determine. If the accelerated Ball joint wear is worth the extra FE of the lowered front
I would rather keep it low and find some geometry corrected control arms . Then 4 link and bag the rear for load compassity.
Point#3
Appearances can be deceiving.
Some of my design requirements to call a truck a truck it must maintain the ability to:
1 haul 1 cord (4'×4'×8' neatly stacked) fire wood, wet/green Oak ~ 3,000lbs . (This will fit under the cap as in the wrapped load pic the top duse not nee to tuch to bed this load travaled 800 mi with no trouble at 69-75mph)
2 have at least a class 3hitch with a min of 10,000lbs WD
.
If theas 2 are not true itis not a truck, then its a glorified car and the mod isnt practical.
Hence all modds must pass this litmans test
For my cap
easy and quick removal by 1 person (v1.2 =35lbsV1.0=21lbs sub 5min removal, it takes longer to tie it down than to r&r the cap, with my current cap. Note: it duse help to point the truck straight into the wind for installation as the windvaine effect can be strong
Point 4
Allready discussed my method of lowering .. more details to solve this lost compassity. Add some ride hight controls mechanical lenkage or go high-tech decade old tec magnetic, these are both load compensateing .
Eg of a random load that found its way to my truck to day



Moons would help .
Larger mirrors are already wanted . For towing safety.

Sealing off the cab i finally spent the $3 on pool noodles on tusday on Wednesday I got a personal best on my 200mi mpg test route 29.3south and 27.26north an aproxamitly 1.5mpg improvementin each direction . I have wanted to rebuild the headache rack when I first built it (I should have measured twice and welded once .to close the gap to .5-.325" .
Nice truck .
Like they say no pic no happen so

[kach22i]

gumby79 you are to be commended for using your truck like a truck, for ingenious packing/loading skills and just the functionality in general. I did not realize the cover was able to tilt up like that.

I'm not a big fan of lowering a truck, Montana where you live and Michigan where I live it makes little sense.

I mostly mentioned it as an alternative.

In design one makes design decisions, best way make a decision is to have a choice between two or more schemes. I'm sure you went though many ideas and tossed out more than you kept to arrive at your current configuration.

Thank you for the detailed and well documented explanation, I feel like I learned something.

SIDEBAR: If you know of any International Scouts (1960-1970) for sale out your way which might NOT be showing up through the usual Internet resources, give me a shout. For some reason I'm attracted to boxes on wheels, perhaps it's the challenge of getting them to be more aero friendly, not sure.

I wonder if they make square or rectangular stock pool noddle extrusions. Might fill the gap between cab and bed a little more cleanly. What you have done now looks pretty good, but I also understand what I am looking at. Strangers to aerodynamics might not be so accepting, but screw them.

[freebeard]

I hope I haven't offended

Well, I'm offended by that. Man up! It's only words.

Corection the hitch is 38"w 2.75×2.75 sq. It hangs 13"lower than the lowest sheet metal and 17below the bottom of the bed over a foot off the ground.

This is your main constraint. All the air below the vehicle has to be herded through that opening. An at least partial bellypan, of course. I suggest a difusser made by fences that start inside the rear tires and curve outward to 38". Like this only with more ground clearance.



The only reasonable angle for the tailgate is 0°, so as to not compromise load/unload (it's in the middle of the wake anyway). There is a 17x38" space below that could have some structure added or unfolded.