Cooling Drag

[skygazer6033]

One of the sore spots of streamlining a vehicle or aircraft is cooling drag. Every IC engine is cooled by the transfer of heat to the ambient air either directly through cooling fins on an aircooled engine or indirectly through liquid coolant to a heat exchanger (radiator). Both cooling fins and radiators job is to increase surface area to radiate heat into the air. Unfortunately more surface area means more drag. Radiators and fins are engineered to provide adequate cooling under all forseeable circumstances therefore they provide far too much cooling and therefore drag under most circumstances. Some cars have shutters in the grill to cut down on cooling drag at cruise speed. Aircooled recip powered airplanes have cowl flaps for the same purpose. The only mention I've read from Elio is they intend to redesign the front because the inlet is too big. Articulated inlet flaps or shutters could be incorporated in the redisign. This could increase aerodynamic efficiency at minimal cost. Thoughts and views on this.

 

[NSTG8R]

Been thinking about this too. Won't know until I have my Elio, but I was thinking about closing off the bottom of the engine compartment with a Kevlar plate/cover [light and tough as nails], and venting the hood [something like the pic] to route the air over the roof, and streamline the air flowing under the vehicle. Might even help to keep the bugs off the windshield too!

 

[JEBar]

while I do believe that when the Elio goes into production it will be a fine vehicle, real world lessons learned will lead to improvements/changes in subsequent models .... it will be really interesting to follow those changes

Jim

 

[skygazer6033]

NSTG8R--- I know what you're saying. However air doesn't always do what is obvious. When in motion a car developes a high pressure area at the base of the windshield. You could end up with the air trying to blow forward into the hood. I believe a better air exit to be on the sides. We already have stylized body crease in that area so it would look completely normal for an air exit vent there. Don't know how the front wheel spats would effect the aerodynamics in the body side area.

 

[NSTG8R]

NSTG8R--- I know what you're saying. However air doesn't always do what is obvious. When in motion a car developes a high pressure area at the base of the windshield. You could end up with the air trying to blow forward into the hood. I believe a better air exit to be on the sides. We already have stylized body crease in that area so it would look completely normal for an air exit vent there. Don't know how the front wheel spats would effect the aerodynamics in the body side area.

Like older Trans Ams and Formulas...Hmmm, possibility there. Then again, I see lots of supercars with vented hoods. I was thinking if I could match the angle of the hood vents to mimic the angle of the windshield, it would keep the airflow around the car cleaner that dumping out the bottom. Gotta get this thing (Elio) modeled and see if I can get a CFD program in my 3D boat design software to run it. Might work, might not, but I've got some time (1yr) to play around with some ideas I've been having. Keep the thoughts coming guys (and girls)!

 

[zelio]

One of the sore spots of streamlining a vehicle or aircraft is cooling drag. Every IC engine is cooled by the transfer of heat to the ambient air either directly through cooling fins on an aircooled engine or indirectly through liquid coolant to a heat exchanger (radiator). Both cooling fins and radiators job is to increase surface area to radiate heat into the air. Unfortunately more surface area means more drag. Radiators and fins are engineered to provide adequate cooling under all forseeable circumstances therefore they provide far too much cooling and therefore drag under most circumstances. Some cars have shutters in the grill to cut down on cooling drag at cruise speed. Aircooled recip powered airplanes have cowl flaps for the same purpose. The only mention I've read from Elio is they intend to redesign the front because the inlet is too big. Articulated inlet flaps or shutters could be incorporated in the redisign. This could increase aerodynamic efficiency at minimal cost. Thoughts and views on this.

Won't something like this add weight? :-) Z

 

[Craig]

NSTG8R--- I know what you're saying. However air doesn't always do what is obvious. When in motion a car developes a high pressure area at the base of the windshield. You could end up with the air trying to blow forward into the hood. I believe a better air exit to be on the sides. We already have stylized body crease in that area so it would look completely normal for an air exit vent there. Don't know how the front wheel spats would effect the aerodynamics in the body side area.

You are correct. Back in my day, it was called cowl induction.
http://www.ehow.com/about_5571485_pros-cowl-induction-race-hood.html

 

[Terrence]

After the Elio is produced and magazines review the Elio, I hope they include an image of the Elio in a wind tunnel so I can see the air flow with actual drag numbers. Too Cool Elio in 2015 and 84 mpg.
Just recently in the Wall Street Journal September 9, 2014 (page B1 marketplace), they cover the topic of substituting super glue/ adhesives for welds or rivets, screws or bolts with Ford, BMW and GM to save weight. Reducing the weigh of welds-screws-bolts-rivets with the minimal weight of adhesive bonding. That for them contributes to weight saving and thus minor mpg increase.
My, the Elio weight is 1,240 lbs, 84 mpg and cost $6,800.00 <> go team Elio!
Terrence

 

[NSTG8R]

You are correct. Back in my day, it was called cowl induction.
http://www.ehow.com/about_5571485_pros-cowl-induction-race-hood.html

Silas Sunday to the rescue! This is exactly the type of hood venting I was thinking about. Well forward of the windshield (no cowl induction), and with the ridge on the hood just in front of it [hard to see in the pic], it's pretty much guaranteed to be a low pressure area. Might even get a little windshield de-icing action out of the deal!

 

[outsydthebox]

.......... We already have stylized body crease in that area so it would look completely normal for an air exit vent there......

I agree. And add temperature/thermostat controlled "shudders" mounted flush with the nose (instead of recessed) in the grill opening.