Full boat tail on a Matrix

[Weather Spotter]

Just where might I find such a spray? I also want to paint it all to match the car and paint will not stick to silicone.

[euromodder]

Originally Posted by Weather Spotter

Does the back snow build up something I can fix or will it be there unless I taper it to a point?

Slightly lengthening the sides, top and bottom with sharp edged plates extending beyond the rear face might reduce it - giving the air something to cleanly detach from (see those sharp edges in rear bumpers).

An even longer plate mounted horizontally on the bottom might work even better to keep the white stuff off the rear - and work like a stern plate.


You could trial with cardboard, then make something more permanent with clear plates so it doesn't obscure the lights.

[Weather Spotter]

Good ideas euromodder

I had to run into town today, the roads are slush covered but I did get a good idea if any snow/slush was getting under my belly tray. I could not see any. Only two places on the axle had slush on them and that was not even to the top of the axle.

[aerohead]

Originally Posted by Weather Spotter

Update: test run

Today I needed a tube of caulk and some 1x2s to make a floor in the tail. My brother was heading off and so I had him follow me for a mile and watch the light snow flow off the tail. Then we swapped cars I and watched. I also took a video clip (not sure how to embed so here is the link) :

Nothing fell off on my trip into town. I taped the gaps and the tape held just fine.

I also took some pics:








snow build up, so I think this area could use some help:


Ideas?

Weather,I'm late to the party so first off let me say 'wow',I'm really impressed with your project!
I watched the videos and have been burning the still photo images into my brain.
*The transition down the roofline of the Matrix and onto the tail looks good.
* The sides appear as though they are not 'bulged-out' as much as the Matrix body but I understand how complicated it is to do a perfect integration from one to the other.
* Without photos from above,looking down,it's difficult to figure the 'curvature' of the sides as they project rearward from the Matrix.A straight sided cone is going to offer drag reduction but with a bit of penalty compared to the extremely complex compound curves of an organic boat-tail.
*Also,as I'm sure you are well aware,the sharp intersection between upper sides and roofline are apt to produce some vorticity.And of course,to construct a radiused intersection there requires drastically more time to fabricate!
* So there may be a little drag penalty with all that,but as you may have considered going into the project,could easily be justified against the additional trouble to construct.
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* As to the bottom,without a complete bellypan,some mid-section turbulence is probably being maintained from the end ofthe forward pan,all the way back,cutting into the performance of the aft pan/diffuser.
* The belly of the tail is steep,with separated flow,and without a movable diffuser which raises and lowers,the steepness is something we have to live with to survive driveway ramps and the like.
* The back-soiling of snow is normal,as the sharp cut off of the tail forces separation and the turbulence transports the snow into that area.The recommendation to install short panels all around the periphery of the taillight area I would second.
* I also second the recommendation for tufts when you can do it.The snow,while quite light,has much more inertia than the air,and will not give as fair an evaluation of flow as smoke,inkblots,or tufts will.
* Living in a 4-Season environment may require that mods be done which can 'grow' with three of the seasons,then 'retreat' for winter.
If you can find it in you to complete the pan it will be like an insurance policy for all the aft mods.Hucho and others tell us that the onset flow to the rear of a vehicle must be absolutely perfect for rear mods to perform.Cleaning up any upstream turbulence will pay big dividends!
I think your numbers are well in range.Next spring I think you'll be all smiles at the gas pump.Great work,thanks for doing all that!

[Weather Spotter]

aerohead, nice summery and comments.

I might make the end panels per the suggestions, how long? Can I make it come to a point?

I might do some tuft testing when it warms up. Most modding has come to a frozen stop

As for the sides, I need to do some work on the transition from car to tail. Right now I have it changes angles twice, at the car and at the top end of the window. The angles might need a bit of work but that is fill in and finish stuff, on hold till temps are 45-50F (mid march).

You are right in that I decided for the squared off shape due to the labor needed. To be totally honest I only sketched it out, most of the design came during building phase.

I may do a mid section belly pan, But I need more material I am out of any good sized colorplast or sheet metal. It is also easier to get under the car without winter gear on.

If I do 3 season mods they will only be on for 6-7 months a year

any tips on reducing Styrofoam squeak?

[arcosine]

It seems to be kicking up alot of snow, looks like a fair amount of turbulence under the car and blowing out from the front wheels. Cool video. Cool boat tail.

[Weather Spotter]

I think most of the turbulence is due to the tires. Watch a car on a snowy or rainy day and see the wake coming out sideways. I have that blocked but the tires can still kick up stuff.

[arcosine]

Yes, but look at the exhaust with it starts off, it blows off the top but sticks to the underside of the boat tail. There is not enough flow under the car, air is being pushed out to the sides in the front and not flowing under the car.

[Weather Spotter]

maybe, by the time this run was done the exhaust was not visitable. It is all snow being kicked up by the tires.

[JasonG]

You can get silicone spray at a SCUBA dive shop.

I think the foam rubbing the car body is what is creating the squeak. Especially the bumper cover.