Aero Design Senior Project Community Ideas - Fuel Economy, Hypermiling, EcoModding News and Forum

Aeroguy · 02-01-2017, 02:36 PM

I am currently working on a senior project that revolves around designing, 3D printing and scale model wind tunnel testing various wings, spoilers and other rear attachments (not diffusers at least not yet anyway). Each wing/spoiler is attached to the trunk. I am reaching out to the community for designs for wings/spoilers. I have a few (~14) but I would like more. In addition, if there is anything you would like me to test for you, please let me know. The car is a 1/24th scale EM1 Civic Coupe. The wings will be tested for drag and downforce/lift. I may or may not be able to translate these into real world values but at the very least they can be compared to one another (and stock).

Thanks for taking to the time to read this.

rumdog · 02-02-2017, 10:00 AM

How bout testing a bonneville flat spoiler - on rear of trunk?

ChazInMT · 02-02-2017, 10:08 AM

OK, I'll say it. Sounds like a cool project. However, the spoilers on the trunks of cars are not a significant aerodynamic feature when it comes to ecomodding. Even if optimally designed, the spoilers offer only a very small MPG gain. However, they may have a significant impact in the negative light on MPG if done improperly.

Still an interesting project with possible insights for high performance applications with high speed and handling aspects.

It's the overall shape of the car that results in its ultimate Cd, since the trunk spoiler area is such a small part of the overall design, and is in the very turbulent wake area, it's ability to have a large impact isn't that big.

Prepare yourself for only very small variations from one design to the next.

kach22i · 02-02-2017, 11:49 AM

Sixth generation (1995–2000) – EK2, EK3, EK4, EK5, EK9, EJ6, EJ7, EJ8, EJ9, EM1
https://en.wikipedia.org/wiki/Honda_Civic

Quote:

The first Civic Si coupe EM1 was introduced in 1999 until 2000.

Using the forum's "Aero-Template" as a starting point.
Aerodynamics by George Kachadoorian | Photobucket

My guess is that anything beneath the red line and in the green area will have little affect.

On second thought, something right up to that line like the early Ducktail on a Porsche 911 (1973-1974 RS) should reduce lift by getting flow closer to the template.

What I meant to say is the wing on the red car is not in the flow and does little.

Wings; should be placed above the green area for maximum affect.

Spoilers; should be placed at or below the green area for maximum benefit.

The biggest challenge in conversation is in discussing spoilers which look like wings but are really spoilers as they allow no air flow underneath the alleged wing.

This has been a big problem in the forum before.

There may be little discovery of many new forms for these cars as they are the most riced out in history with aftermarket accessories. Could be a public service testing what's currently out there. And then from that data base create your new form/shape.

EDIT: If anyone can find a better side view please post it, I had a devil of a time just finding this one.

Aeroguy · 02-02-2017, 12:23 PM

Rumdog - I have designed many wings (or spoilers?) of that style

ChazInMT - You're more correct than I'm sure you could ever imagine haha. I have two different setups, one to test downforce and one to test drag. The one for downforce works beautifully, but the drag one has been having issues of not reading enough on the force gauge to see any differences. With any luck this issue will be fixed by next week.

kach22i - I actually did test a ducktail for one of my designs. Look up a Rocket Bunny 240z to see a similar style wing. Strangely enough at both high (40 mph) and low speed, the spoiler zeroed out the lift of the car. For a good side view, google "civic coupe dimensions".

kach22i · 02-02-2017, 12:34 PM

Quote:

Originally Posted by Aeroguy

For a good side view, google "civic coupe dimensions".

That is a pretty good search phrase, however I don't trust anything I see, they ain't worth a darn.

I have a pretty good eye and so far nothing I see is more accurate than the perspective ridden view already posted.

Who draws these things, drunken Russian teenagers?

EDIT:
Might be a 1999-2000 2-door Honda Civic in this thread, no guarantees.

http://ecomodder.com/forum/showthrea...ead-26678.html

Aeroguy · 02-02-2017, 12:39 PM

Quote:

Originally Posted by kach22i

That is a pretty good search phrase, however I don't trust anything I see, they ain't worth a darn.

I have a pretty good eye and so far nothing I see is more accurate than the perspective ridden view already posted.

Who draws these things, drunken Russian teenagers?

I could try taking a picture of my model. I have a legit camera but I don't know how good I can get it. Precision is not really the main focus here. All the wings are attached by hand for instance. I'm kind of more looking for general ideas for shapes and such rather than discreet dimensions.

kach22i · 02-02-2017, 01:20 PM

Quote:

Originally Posted by Aeroguy

I could try taking a picture of my model. I have a legit camera but I don't know how good I can get it. Precision is not really the main focus here. All the wings are attached by hand for instance. I'm kind of more looking for general ideas for shapes and such rather than discreet dimensions.

Sounds like you have a good foundation and understanding already.

What I think perhaps is a neglected aspect of rear spoiler and wing design is the termination edges. That is to say the corners and also plan view alterations from being so monolithic and straight planed.

As a guide look at the tip of aircraft wings or winglets which attend to the pressure differences which create vortexes as having more variations and innovations than NACA wing sections. Some of these wing tips are inspired by nature (bird wings) for instance.

I think it would be great if rear spoilers were given similar attention.

For instance, take your Rocket Bunny 240z; what if the corners had little wavy edges to break up resonance nodes and to mediate various angles of attack found in turning/curves?

Cars may be driven mostly in straight lines, but recent CFD studies are including various geometries of the vehicle in motion in a more 3D sense than in previous decades.

So there you go, my concept deals with plan view sweeps and curves to cup or deflect the air flow and air pressure. Coupled with top edge and corner treatment of spoiler shapes, undulating/wavy/curved/serrated and so forth.

Background: my hovercraft experiments dealt with sound mostly, sound is wasted energy or energy built up at specific frequencies. The splitter on my hovercraft spread some of this energy around to lower peak levels. If such an ideology were applied to a rear spoiler there could be a greater range of use out of it (useful speeds and or angles of attack).

Making Curves - is this one way? - Boat Design Forums

My Photobucket:
George Kachadoorian's Library | Photobucket

Related old thread;
http://ecomodder.com/forum/showthrea...ign-22101.html

Quote:

Originally Posted by Bennett_Racing

Morning all, Can someone explain the reason for these 'notches' in this wing's gurney flap please? are they vortex generators?

One really good response to that old thread:

Quote:

Originally Posted by aerohead

My guess is that without the whale fin tubercules,or raptor feathertips,that there is something about the frequency and amplitude of the shedding vortices approaching the dragsters body that the crew didn't like,so they've altered them with this mod.Which goes with the 'accoustics' comment mentioned by Kachi above.

Aeroguy · 02-02-2017, 01:34 PM

As far as winglets are concerned, I believe you are referring to what are called endplates in terms of cars. There is a good example on Mulsanne's Corner and I have uploaded an image of one of the wings I designed (it has something similar to a NACA 4412 airfoil flipped upside down) and there end plates on it although they are built into the mounts. imgur. com/a/PhFcd (I don't have enough posts to post links yet).

I am having a hard time understanding what you are getting at with the wavy corners. Is there any way you could sketch something out so I could get a better idea. I'm not really knowledgeable enough to understand the acoustic side of aerodynamics. I've never really looked into it.

kach22i · 02-02-2017, 01:58 PM

A picture is worth a thousand words, these two designs do not curve in plan, would have to draw by hand to illustrate that intent. Maybe will do later.

Again, this isn't for looks (selling/marketing), it's for testing and exploring an idea.

Started with this image off the Internet, used a really crude photo editing program. I can draw, but wanted to keep this simple to start with.

Aerodynamics by George Kachadoorian | Photobucket

Taking it a bit further.

Now I made you all hungry for the wrong foods, right?

https://www.walmart.com/ip/Great-Val...16-oz/46460985

I would expect these designs to break up the edge pressure differentials similar to they way they for frequency nodes for sound. The advantage is less lost energy to peaks and transitions. The mass of air would still behave the same I suspect, the interactions at the top edges would be flattened out, an irony considering all the curves and undulations.

You wanted something to test, be careful what you ask for.