Cooling Drag

[NSTG8R]

I am expecting to see many mods like this become available in the aftermarket which should help improve those MPG numbers even more. Another addition would be an undertray as EM has said they are designing a smooth underside however it may not be fully smoothed out with an undertray as that would cost more.

I would love to see someone design an undertray which even attempts to direct air around that rear tire which does add drag. To my mind to accomplish this the undertray design would have to be shaped to create an air curtain like effect around the tire as you could not have something hanging down too low on the underside.

Not sure if this is what you had in mind, but the Porsche 914's have flaps (vortex generators?) just forward of the cylinders to create a low pressure area there. Helps with the airflow through the engine tin when you're up to speed. Kind of hard to see in the pic, got the yellow arrows pointing at them. I could see like a half conical shape on it's side, narrow end forward (rubber) just forward of the rear tire might do something similar. Just thinking...

 

[skygazer6033]

Ultimately a belly pan should completely flat and sealed with only enough air allowed to circulate to flush out any exhaust gases. A boat shaped rubber splitter forward of the rear tire flexible enough to deflect upon impact with road debris. Not sure how low it would need to be to be effective. Seem to recall seeing 1.5 inch somewhere. Maybe something similar in the leading edges of the spats.

 

[goofyone]

Not sure if this is what you had in mind, but the Porsche 914's have flaps (vortex generators?) just forward of the cylinders to create a low pressure area there. Helps with the airflow through the engine tin when you're up to speed. Kind of hard to see in the pic, got the yellow arrows pointing at them. I could see like a half conical shape on it's side, narrow end forward (rubber) just forward of the rear tire might do something similar. Just thinking...

View attachment 2745

Yes this is exactly what I am thinking about. It will be fun to play with this kind of thing when we finally get a chance!

I don't believe it will be very hard to mod the Elio enough to achieve over 100 MPG on the highway. Just need a combination of the items we have been discussing.

 

[skygazer6033]

NSTG8R --- I like your half cone better than my boat shape.

 

[outsydthebox]

NSTG8R --- I like your half cone better than my boat shape.

I like your idea of a rubberized piece. I have been picturing something (shaped) like a shark fin antenna, turned upside-down, with the back of the fin "open" with the tire kind of "tucked in."

 

[NSTG8R]

I like your idea of a rubberized piece. I have been picturing something (shaped) like a shark fin antenna, turned upside-down, with the back of the fin "open" with the tire kind of "tucked in."

Sounds good, shark fin or boat bow shaped like skygazer mentioned, but I think we'd need to leave enough room between the air deflector [for lack of a better term] and the tire, so that if...more like 'when' you hit some road debris, it won't cause contact between the deflector and the tire, might end up making some of your own road debris . Maybe the deflector would be better mounted to the rear wheel swing-arm so it would travel with the wheel, and not the floor pan...Man! Can't wait to see what the bottom of the Elio (production model) looks like.

 

[ElioDigger]

I put vortex generator s on the back of my smart. Cleaned up air flow and made it smoother on the highway.

 

[Mark Ambrose]

I used vortex generators (VG's) on both my homebuilt airplanes to lower their stall speed. These things work beautifully. I have a couple hundred VG's left over and plan to experiment with them to keep the flow attached over the aft of the body to reduce drag. Very simple to "tuft test" your work by having someone driving next to you to video how the tufts of yarn are behaving.

 

[NSTG8R]

I used vortex generators (VG's) on both my homebuilt airplanes to lower their stall speed. These things work beautifully. I have a couple hundred VG's left over and plan to experiment with them to keep the flow attached over the aft of the body to reduce drag. Very simple to "tuft test" your work by having someone driving next to you to video how the tufts of yarn are behaving.

Oh yeah Mark! Some yarn, tape, a buddy with a Go-Pro, and an open stretch of highway...who needs a windtunnel?

Just curious. Are they attached to the wings, the fuselage, or both?

 

[skygazer6033]

NSTG8R --- Vortex generators can be used anywhere laminar boundary layer airflow is separating. Separation is turbulence, turbulence is drag. VG's wind up the air, keeping it laminar longer. When used forward of control surfaces keeps controls responsive deeper into the stall. Allows an aircraft to mush along slowly fully controllable rather than stalling and snapping into a spin. Anyway on an Elio use to reduce drag.