Honda Insight Under-body Smoothing Panels (custom belly pan / undertray)

[3-Wheeler]

After purchasing a used 2000 Honda Insight, several things came to mind when attempting to change the oil:

1) Before the oil could be drained, several panels had to come off.
2) The existing panels were rather flimsy, and might move easily in the wind
3) Getting the panels back on in cold weather, was shall we say, 'interesting' with cold fingers.

That made it obvious that something would be done when warm weather came in Wisconsin.

In May of 2009, 1) the motorcycle was brought out of winters hibernation to get back and forth from work, and 2) the Insight was jacked up to determine how new panels could be implemented. After accessing what hard points were available, construction was started on the mounting system.





Hard mounting points for the support rail were embedded into components on the car.




Making a curved surface, requires many smaller blocks glued together.


Here you can see the blocks filed down to a smoother shape.


Here's a close-up shot of the blocks.


You can see the many small blocks that are added together, to make the overall shape.





This shot shows the panel about one foot in front of the second catalytic converter. In the foreground in an access hole for changing the oil filter.


A detail shot showing the hard mount points and embedded wood blocks that act as stress relievers to the relatively soft foam.


Now you can see the panel extending rear-ward towards a new hard mount point. Also, in the middle of this picture is the access hole for the oil drain. There is a fumoto oil drain valve mounted there to aid in easy oil changes.


Fresh blocks of foam are being glued in this picture and extend to where the drivers side panel will be started later. The drivers panel was missing when I bought the car this spring.


This shot shows the start of an inverted airfoil, covering the underside of the suspension arm.


Start of the inverted wing shape on the drivers side.


This shot shows just how complicated the shape is on the back side of the panel. You can imagine the hours it took to shape all of this.


A close-up of the contour shape of the back side of the panel.


This is the same area after smoothing out the area. This will allow the glass cloth an easier time of adhering to the complex shape. More shaping is yet be done, however. The foam needs to be very smooth before glassing.


Now the back side of the panel is starting to take shape!!


This area is a little thin and weak, so another layer of foam is added for strength.


Here is the shape smoothed down so the glass cloth will transition the shape easily.


The is the blocked-out area of the suspension airfoil.


After shaping with a rasp file, here is what the shape looks like.


Here's an edge view of the airfoil.


Airfoil almost finished now.


Panel is back on the car now, and the wheel well area being filled in. This accomplished two things:

1) Support for this portion of the panel.
2) Keep snow from being packed under the panel in this area.

The car is primary transportation in the winter.


Adding yet more blocks.


This area is almost filled-in now.


Hey, just about done. A pair of wood blocks are used to hold the two portions of the panel together in this area.


And the same thing on the front side of the wheel-well.


A backside view of the almost complete panel. Notice all the hard-mount locations. This is ensure that snow does not pack behind the panel in cold weather.


This shot shows the geometric layout of the panel's backside.


You can see the embedded wood blocks, to allow attaching to the car.


Here's the panel flipped over and just about smoothed out. If this were a car body panel, the entire surface would be glazed, sanded, primed, and painted. This process would take about one more month to get smooth for exterior body panels.

The project has taken six weeks at this point.


A detail shot of the oil filter access panel, and oil drain hole.


And the recently fiberglassed wheel well supports.


And the front side.


This shot shows the tight fit of the panel on the car body.


Jim.

[silverinsight2]

Fannnntastic, it must have taken a zillion man hours.
I can't wait for the mpg testing!

[aerohead]

Your attention to detail is what will make or break the performance of a bellypan.I'm very impressed! Did you add the Dzus fastener weld plates? or is that something Honda already used? Those 1/4-turn fasteners are a great way to go.Thanks for sharing the thread.

[3-Wheeler]

Originally Posted by silverinsight2

Fannnntastic, it must have taken a zillion man hours.
I can't wait for the mpg testing!

It took all summer to make the engine and drivers side panels, which would be about 2-1/2 months.

As for MPG, I seem to be getting about 7 mpg more than before. Average is about 81 with 60F temps, and this is over a full tank of gas.

Next spring, I would like to perform Cd generating coast down numbers using a hand-held GPS device that sets on the dash.

Jim.

[3-Wheeler]

Originally Posted by aerohead

Your attention to detail is what will make or break the performance of a bellypan.I'm very impressed! Did you add the Dzus fastener weld plates? or is that something Honda already used? Those 1/4-turn fasteners are a great way to go.Thanks for sharing the thread.

aerohead,

Thanks for input. I have read many of your various threads on 'aero' issues, and find many of your comments very interesting. In fact, besides reading about the aerocivic, I find the aerodynamics area the most interesting part of EcoModder.

As for the fasteners, I used various fasteners in different areas. Since the panels are not likely to be removed very often, most are fastened with course wall-board screws. These fasteners are either screwed into the aluminum under body rails or into custom made wood substructures that are epoxied in place. A few of the fasteners are machine screws.

Jim.

[ChrstphrR]

Thanks for letting us see what you did over the summer! It's making the gears in my head turn for building a hybrid foam/fibreglass/metal tray in sections for my car.


I'm curious, though, about some of the unmentioned details of your build.

Did you glass over the top/inside surface of your tray?
Did you coat or prep the rest of your wood you mounted on the car to secure the tray?

I know the foam used would be impervious to water/slush/snow, but all the wood used, is another story entirely.

[Wonderboy]

This is really nice work - thank you for posting this. Exciting!

[silverinsight2]

just cross posting this picassa link from insightcentral

Picasa Web Albums - jsmosher - Air-Smoothing...

[NeilBlanchard]

I nominate this for the Mod of the Month!

(I installed CoolIris so I could use it on the Picassa page...)

[3-Wheeler]

Originally Posted by ChrstphrR

Thanks for letting us see what you did over the summer! It's making the gears in my head turn for building a hybrid foam/fibreglass/metal tray in sections for my car.


I'm curious, though, about some of the unmentioned details of your build.

Did you glass over the top/inside surface of your tray?
Did you coat or prep the rest of your wood you mounted on the car to secure the tray?

I know the foam used would be impervious to water/slush/snow, but all the wood used, is another story entirely.

Hi Christopher,

Both the top and bottom side of the foam board is glassed over. This is known as typical 'composite construction'. The foam board by itself is not very strong, but very light. A layer of glass cloth impregnated with resin is itself is not very good in compression, but very good in tension.

When the two are added together however, now you have a very light, yet strong structure. Plywood is another composite structure of sorts. It utilizes various layers of grained wood to make a structure that is stronger than the base wood would be without the cross-grain structure.

All of the wood supports mounted to the car have been epoxied to keep the water out. The only weak area is were the wood screws hold the panels onto the car. Water can seep into those areas. Only time will tell how this holds up.

I do have a motorcycle fairing with 115,000 miles that is constructed in a similar manner and still looks good, but it is not mounted underneath a car body either. However, the fairing still gets rained on just like the car, since I typically ride it rain or shine when it's warmer, such as this summer when working on the smoothing panels.

Jim.