Maxus get a acrylic rear spoiler

[mtb9153]

Looking at the attached picture, that is not what I had in mind.  My idea was just to construct an extension of the factory rear spoiler which I feel falls short of it's intended purpose.  I guess I was not aware that the tuft tests which have been done showed no area off the rear spoiler for improvement.  The picture shows an extension of the cars shape in the back into a much longer car which I don't have any desire to do.

[ScubaDadMiami]

Even if it just takes care of the dust that clings to the rear of the vehicle, that would be worth it.

[mtb9153]

Well now I'm not sure I'm going to do it since I'm reminded that the tuft tests shows very little need for laminar flow improvement at the top of the hatch.  Somewhere lower or at the bottom of the glass appears to be the area most needing improvement.  But I haven't come up with a good design for that portion.

[62Lincoln]

I might have missed this, did you decide not to order the rear spoiler from Loder in Germany?

[mtb9153]

Yes I decided against ordering his spoiler, the design just wasn't aggressive enough for me to think that it would improve the turbulance issues on the back of a CMax.

[mtb9153]

I have ordered from Tap Plastics a new piece of clear Acrylic which will be custom cut to attach to the rear glass with 3M gel adhesive just under the windshield wiper and run across the full width of the glass.  I did some tuft testing today using some red yarn I bought at Michaels craft store.  I took video using my GoPro 3 on their suction cup mount which by the way fell off while driving.  Much to my horror as I saw in my rear view mirror as it was being run over by the car behind me.  This is why you should never hang your expensive GoPro outside your car without being inside the clear plastic housing it came with.  When I came back to pick up my camera, I found the front cover of the housing totally smashed with the lens cover shattered to pieces, but the camera inside was still filming believe it or not?  I did break the small LCD screen on the front of the camera, but hey! the camera still works.  I put the camera in my backup housing and good as new...WHEW!! :clapping: When I get the footage edited I will post it to this thread.  I did notice quite a bit of erratic movement of the yarn strands I taped to Maxus across the bottom of the rear window.  They were all twisted around themselves when I got home so it appears there is a great deal of dirty air turbulence across the bottom of my rear window.  The only strands which seemed to stay relatively under control at freeway speeds were the ones I attached to the middle of the rear glass.  Even the ones across the rear bumper just below the liftgate were pretty messed up while driving in the 40-45mph range on surface streets.  Was a good test but messed up my GoPro.

Edited September 19, 2014 by mtb9153

[fbov]

My condolensces on your GoPro, but your story is almost as good as the old Timex commercial where John Cameron Swayze stands on a sand bar while a boat slides up the sand to reveal a watch on the keel... "Takes a licking but keeps on ticking!" Given their application, GoPro probably has documented lots of these kind of things. I mounted mine ($70 dashcam) on a monopod and drove a chase car for this reason; you'll recall the upside-down video...

 

What you report from your tuft test is consistent with my observations:

- attached, non-tubulent flow down the glass, at much lower velocity than roof or sides

- detached, turbulent flow below wiper level, basically tail light-to-tail light, down to the bumper

 

I still see an opportunity separating these flows, or moving their confluence farther back in the wake.

 

Have fun,

Frnak

Edited September 19, 2014 by fbov

[mtb9153]

Fbov I remember that commercial I'm sorry to say, guess that means we both have been around for awhile?

[kostby]

There is a lesser-known John Cameron Swayze commercial where "his" Timex was attached to the prop of a small boat motor in a tank of water...

 

[ptjones]

Sorry to hear about your GoPro, It's good you got some info from the test.  What I would like to do is to attach a piece of cardboard vertical on the back of car with tuffs on it. Extending a couple of feet so you could see whats happening with the airflow behind the car. That way you could monitor what happens when you add spoiler or other aeromods. :)

 

Paul

[mtb9153]

Interesting thought Paul, might have to ponder how that could be done and get good results.  That would really get locals looking at me.  The strands of yarn had drivers scratching their heads as it was.  Only the performance minded drivers understood what I was trying to do.

[mtb9153]

I tried my new custom cut piece of acrylic on the tailgate at the bottom of the rear glass.  It seems to cause a very erratic behavior of tufts placed on the glass above the spoiler which were pretty stable without the spoiler so it seems to have a reverse affect.  Not sure this is the answer to the dirty air problem behind a CMax. 

[scottwood2]

Thx for the update.  Any pics?  How did it look?  I would like to see what it looked like.  

[mtb9153]

I want to conclude my findings from the tuft testing I've been doing both with and without a rear spoiler in place. 

 

I conclude after spending $100 for a piece of custom cut acrylic that there is NO benefit to installing a rear spoiler anywhere on the back of a CMax.  My tests showed erratic behavior of the tufts placed on the rear glass across the rear hatch and below across the bumper.  In fact with the spoiler placed under the rear glass the tufts across the glass got even more active in their movement to the point where they were twisting themselves around the tape which secured them to the car.  With the spoiler it did nothing to clean the air flow over the tailgate and the rear bumper.

 

This leaves me to think that the only way to possibly clean the flow of air behind a CMax is by developing some sort of rear air diffuser to refine the flow of air coming out from underneath the car.  I'm shelving the idea of a rear spoiler as a functional piece of equipment.  I see it would only be a piece of eye candy for giving your CMax a sportier look if that appeals to anyone.

[fbov]

Sometimes, Brother Mike, data sucks... but it doesn't lie! Reality is what it is. Thanks for the effort!

Frank

[mtb9153]

Yes it was a valiant effort but not to be it seems :sad: :banghead: thanks Frank now if I could just convince my wife it was worth the effort and the $100 for nothing. :rant: :rant2:

Edited October 7, 2014 by mtb9153

[fbov]

Testing has never been free... sometimes you get a return on your investment, other times, not so much. The price of failure is therefore higher than the price of success, but it's not a waste of money, as you always learn someting.

 

Too bad I can't see what I'm typing... can't see how I can post a reply... the internal pop-up ads are going to kill this forum for me!

 

HAve fun,

Frank

[kostby]

 My tests showed erratic behavior of the tufts placed on the rear glass across the rear hatch and below across the bumper.  In fact with the spoiler placed under the rear glass the tufts across the glass got even more active in their movement to the point where they were twisting themselves around the tape which secured them to the car.

 

Honestly, most of our driving is in town and short trips on the interstate (30 minutes or less), so we're not likely to travel fast enough, or long enough, that a reduction in drag from a rear spoiler is going to significantly affect fuel mileage...

 

but maybe your test WAS successful from another standpoint: 

 

I DO wonder if that extra turbulence created on the surface of the glass above the spoiler is enough to keep the hatch window clean(er).

Edited October 9, 2014 by kostby

[mtb9153]

Honestly, most of our driving is in town and short trips on the interstate (30 minutes or less), so we're not likely to travel fast enough, or long enough, that a reduction in drag from a rear spoiler is going to significantly affect fuel mileage...

 

but maybe your test WAS successful from another standpoint: 

 

I DO wonder if that extra turbulence created on the surface of the glass above the spoiler is enough to keep the hatch window clean(er).

Interesting thought kostby, I'm not sure if it would have helped?