Commercially produced aerodynamic pickup bed cap

[freebeard]

That was my hope. The Cybertruck establishes that longitudinal creases can work, but a compound curve give more interior space.

Are you going to roll the sides down as on the left, or go to the corner as on the right? Will the whole thing alligator, or what do you plan for bed access?

[Bicycle Bob]

Originally Posted by freebeard

That was my hope. The Cybertruck establishes that longitudinal creases can work, but a compound curve give more interior space.

The Cybertruck establishes that stylists can copy unsuitable shapes from stealth aircraft, just as they sold millions of cars with unsuitable shapes from supersonic aircraft. Flat panels are not even good structural practice in metal - Citroen used to corrugate them.

[JulianEdgar]

Tuft testing will be very interesting. Once you have attached flow, a rear spoiler lip may further reduce drag and lift.

[tomi_k]

freebeard : Still puzzling with the those two options - straight to the corner (easier, more room, no sharp corners when opening bed door etc.) vs. rolled / blended sides (reduces "sharp" corner between the top and side walls -> tiny vortex, more complicated split line between the cap and cap door but could be a tad better from aero perspective).

So key thing is to keep in mind how to shape whole cap while making sure that it can be also finished (continued after prototyping) and the main cap shape and the cap door shape can be split / separated "easily" and then finish. But main focus for now is to make prototype(s) and get proofs of improvements, and then focus how to make finished one.


Rolled / blended sides as shown on the pics is just one option (they are straight lines looking from the top of the vehicle). More complicated option is to make the view from the top also "tier drop shape" but lets see... And yes, there will be a cap door, almost whole top surface (at least that's the plan) but it's limited to bed length at the moment. The extension piece (when bed door is open as shown) is now planned to be separate piece which can be taken out as needed (to further improve aero -> especially for long distance travels).

JulianEdgar : Was planning to do a half truck tuft (longitudal) test before anything as a baseline and then see what happens with the cap + mods...

In general, after reading this forum (thanks for the Admins, this is great stuff), I am confident that improvements can be made and that they are effective.... just need to get data from my own vehicle.

[tomi_k]

Regarding drag and lift.... trying to minimize tail surface are yet still keep shapes "laminar" hence sharp corner where airflow "wraps" around corners are under details....

Well shaped form will start to remind a wing upper surface which creates lift so need to be careful also while testing....

If all goes well, then next will be underbody mods (full length)....

[Bicycle Bob]

The first time I talked with a professor of fluid dynamics, almost the first thing he cautioned me about was trying to copy skin-on-frame shapes like a glider fuselage. Those creases don't matter for aircraft, but with a crosswind, they throw everything off. Be sure to test for that.

[tomi_k]

If understood the "skin-on-frame shapes like a glider fuselage" correctly, I will take different approach, even for prototype(s).... it will be a firm surface....

[Bicycle Bob]

Originally Posted by tomi_k

Regarding drag and lift.... trying to minimize tail surface are yet still keep shapes "laminar" hence sharp corner where airflow "wraps" around corners are under details....

Well shaped form will start to remind a wing upper surface which creates lift so need to be careful also while testing....

If all goes well, then next will be underbody mods (full length)....

You won't stand any chance of getting laminar flow that far back, but turbulent flow is much more forgiving. Also, since you are not racing, you can probably accept a bit of upforce if it reduces drag.

[tomi_k]

may have my terminology wrong about "laminar".... but target is to get a good attached flow over the whole cap (not turbulent)... testing will show that how well it was achieved....

[Bicycle Bob]

Originally Posted by tomi_k

may have my terminology wrong about "laminar".... but target is to get a good attached flow over the whole cap (not turbulent)... testing will show that....

Large scale turbulence is detached airflow. Boundary layer turbulence is almost inevitable, and works as a cushion. The thicker it is, the more basic drag you get, but also the greater resistance to separation. If a shape is too abrupt, we deliberately add boundary layer turbulators.