Morphic Studies

AriLea said:

Spoilers have a few purposes, which you use if you need it. ( let's not forget looks is often the top reason, but ignore that for now ) So basically you first find out if you need it or not. And what it does depends on the shape and the airflow in that area via the body aero effects.
Down force is one either by 1)creating high pressure zone or 2) as a inverted airfoil. Balancing out a pressure area 3) is another. and then we have; Cleaning up non-laminar flow 4), and moving the center of pressure backward 5). (A tail works better for #5 than a spoiler.)

So straightening out existing squirrellyness is a function of 4 and 5. But once you have the spoiler, you could pick up squirrelly effects if the side wind (or turbulent winds ) undermines implemented effects for any of 1 thru 5. Remember how I said a brick is predictable and a bird is not. Or also to say you can't feel a loss unless you have something to lose. But, I would think if you have problem 3, you would want the fix no mater what. However, fixing the balance at the body is the better solution for #3. So generally that is an after market product.

Well, admittedly all 5 can be fixed at the body. Well that's also a simplification, if you look at aircraft, the body has fixed 1 thru 4, at the expense of #5, so they add a bit of area to the tail.

Anyway it's all a trade off. Generally, use the least spoiler that is still suitable for the effect you need. Then you have the least to lose. So I say, you need to do testing with the existing body to find the problems. A combination of smoke in a tunnel and roll-down testing is likely the best way. It's iterative, slow, expensive, but gives the best final results. Sure-Sure, could/should use simulations first, but that just gives a best first guess.

The poor-man's way is a really big fan and the smoke stick (or load the smoke equipment in the actual car), then make cardboard models of the spoiler(s) and do roll downs on the real car.

We all know what the roll down test is yes?

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AriLea said:

Spoilers have a few purposes, which you use if you need it. ( let's not forget looks is often the top reason, but ignore that for now ) So basically you first find out if you need it or not. And what it does depends on the shape and the airflow in that area via the body aero effects.
Down force is one either by 1)creating high pressure zone or 2) as a inverted airfoil. Balancing out a pressure area 3) is another. and then we have; Cleaning up non-laminar flow 4), and moving the center of pressure backward 5). (A tail works better for #5 than a spoiler.)

So straightening out existing squirrellyness is a function of 4 and 5. But once you have the spoiler, you could pick up squirrelly effects if the side wind (or turbulent winds ) undermines implemented effects for any of 1 thru 5. Remember how I said a brick is predictable and a bird is not. Or also to say you can't feel a loss unless you have something to lose. But, I would think if you have problem 3, you would want the fix no mater what. However, fixing the balance at the body is the better solution for #3. So generally that is an after market product.

Well, admittedly all 5 can be fixed at the body. Well that's also a simplification, if you look at aircraft, the body has fixed 1 thru 4, at the expense of #5, so they add a bit of area to the tail.

Anyway it's all a trade off. Generally, use the least spoiler that is still suitable for the effect you need. Then you have the least to lose. So I say, you need to do testing with the existing body to find the problems. A combination of smoke in a tunnel and roll-down testing is likely the best way. It's iterative, slow, expensive, but gives the best final results. Sure-Sure, could/should use simulations first, but that just gives a best first guess.

The poor-man's way is a really big fan and the smoke stick (or load the smoke equipment in the actual car), then make cardboard models of the spoiler(s) and do roll downs on the real car.

We all know what the roll down test is yes?

Click to expand...

I'll confess... I don't. Unless that's where someone rolls down one window and the buffeting hurts your head... buff buff buff buff...

In a nutshell, how fast does the car slow down, from a speed, tranny in neutral. (I'm making up DWW as a term)

If you can determine the drag from wheels and weight (DWW)( and internal friction), what is left over is from aerodynamics. So on a roll down, you see how fast the car slows from some speed. That is an HP amount, measurable at each MPH. So subtract the DWW for that speed and there you are, the total drag at each speed. There is momentum and change in deceleration involved but let's not mention that.(too much)

But the nice thing is, if the wind is adjusted for, it's very comparable, from any set of two tests. Just accurately measure the time to slow from say 75mph thru 50mph (start at 80 to preload momentum issues) The difference is how much your change saved.

Look up how myth busters tested for golf-ball pits. That's another way it's done, but similar. In the mythbusters way, you don't have to worry about momentum, but each MPH would have to be tested separately. How many different speeds do we care about? 65mph, 55mph and maybe 45?
When you test below 35mph, DWW is predominate. Above 50 in normal cars, aero becomes more so. The nice thing about a constant test via fuel usage, you can increase accuracy via longer runs, if the winds (and temp) stay as expected. Takes a long-long time with very little equipment.

In a rolldown, you get a graph (set of graphs actually) through a range of speeds, but then you have to adjust for momentum to get the aero drag. Then with the frontal area you derive the cd. More technical equipment, very little time. Averaging more runs helps eliminate wind and temp effects.

DWW can be determined from a 25mph to 10mph roll down. Then it's projected as linear up from there. Not 100% accurate, but "good enough for the girls we date!" lol
So typically you do your full roll from 80 down to 5, eliminate 5 off each end, calc the DWW from 25 to 10, and use the results to adjust the 75 to 55. Look at the 35 to 55 just for the fun of it, and as a cross check. Then predict your fuel usage at 55 and do a myth-busters type test run as a double-check.

You can probably do all of the calcs with some software on line somewhere, loading the sampled time-marks.

You guys are ignoring possibility an additional remedy for drag on most any object, car bodies included. It's known as the DIGB effect. Most parasitic drag is the result of air separating from the smooth laminar airflow across any object moving through the air. This is known as the skin effect of a thin air boundary generated on the surface on all objects allowing the smooth movement threw the air. If this air separates from the object turbulence occurs and forcing the air to reattach itself as some point farther down the line or just expelled at the end of the object. The separation simply results and more drag force known as parasitic drag. The teardrop shape is considered the superior or best shape to prevent separation or the ideal shape for minimum drag. All other shapes must contend with premature separation and the resultant drag. Turbulators placed slightly ahead of separation have proven to delay separation and thus decrease drag. To a point the less aerodynamic shape of the object the more these turbulators aid. Case in point, the Dimples on a golf ball are the turbulators that cause the air to stay attached longer and thus to appear more laminar to the resisting air. If you and can put up with the ugly dimples in your paint job running ones car threw a good hale storm would result in considerable number of turbulation dimples and much more aerodynamic vehicle.
OK So I've got the record for the longest joke. BTW DIBG effect stands for dimples in a golf ball.

Folks said:

Snipped: If you and can put up with the ugly dimples in your paint job running ones car threw a good hale storm would result in considerable number of turbulation dimples and much more aerodynamic vehicle.
OK So I've got the record for the longest joke. BTW DIBG effect stands for dimples in a golf ball.

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Every so often the creative rebel in me just has to be heard, or seen in this case...
I just love hacking 4's into 3's.

AriLea said:

Every so often the creative rebel in me just has to be heard, or seen in this case...
I just love hacking 4's into 3's.

View attachment 5790

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Well aint that cute. Also seems others are craving some aerodynamics too;

https://www.youtube.com/embed/NER9X4_gtYk?feature=player_detailpage.

Well, they spent a few million on that one! Very cool though!
Back in my research days the typical one off commercial prototype was 6mil for a sedan.
So at today's prices, (but more advanced tools) and for a carbon fiber trailer and truck? whew a pretty penny I'm sure.

The latest morphic hack.. enjoy!


Edit update: Added 3d graphic to the Sketchup 3d warehouse

As you can tell I'm a bit obsessed with how tandem three wheelers can look very 'hot' and still be a very efficient vehicle. In part because this is still a fairly untapped opportunity. There are a number of interesting prototypes in 3 wheels, but compared to what exists in 4 wheels, just a pittance. Just staying inside an exploration of cloning existing super-cars can take up a person's full career. So I just spend enough effort to give a taste of the resulting form. A lot of this is enabled by the EV drive train, since it can fit in spaces a modern ICE drive can not.
Also conveniently, a 2F1R layout with integrated fenders has huge spaces behind the front wheels for low-laying battery pacts. I try and keep realistic for space allocation and such things of actual seat position, door entry and viable line-of-sight. Door entry remains one of the most challenging aspects. A lifting door is often the resolution to that problem.
Because of the angle of view, the one above could represent a narrow sociable seating or a wider tandem cockpit, but this one below probably is just sociable seating, I'd have to do another cut to what it's look is like in tandem. But the one below had traditional doors, and the one above has to have lifting wing-doors or a clam-shell hatch.

I hope the Elio gets built and this catalog becomes a useful resource to inspire the Elio II.

AriLea said:

As you can tell I'm a bit obsessed with how tandem three wheelers can look very 'hot' and still be a very efficient vehicle. In part because this is still a fairly untapped opportunity. There are a number of interesting prototypes in 3 wheels, but compared to what exists in 4 wheels, just a pittance. Just staying inside an exploration of cloning existing super-cars can take up a person's full career. So I just spend enough effort to give a taste of the resulting form. A lot of this is enabled by the EV drive train, since it can fit in spaces a modern ICE drive can not.
Also conveniently, a 2F1R layout with integrated fenders has huge spaces behind the front wheels for low-laying battery pacts. I try and keep realistic for space allocation and such things of actual seat position, door entry and viable line-of-sight. Door entry remains one of the most challenging aspects. A lifting door is often the resolution to that problem.
Because of the angle of view, the one above could represent a narrow sociable seating or a wider tandem cockpit, but this one below probably is just sociable seating, I'd have to do another cut to what it's look is like in tandem. But the one below had traditional doors, and the one above has to have lifting wing-doors or a clam-shell hatch.

I hope the Elio gets built and this catalog becomes a useful resource to inspire the Elio II.
View attachment 22620

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Have you considered sliding doors rather than lifting? It seems with the 2F1R layout that rearward opening sliding doors would be easy enough to implement.