Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 


Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 02-12-2021, 05:34 PM   #1 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 3,726
Thanks: 36
Thanked 2,464 Times in 1,720 Posts
Angles for Automotive Design - Guidelines

SAE practices
https://www.researchgate.net/figure/...fig1_255700982


I know it's out there, but I cannot find it right now.

What are the recommend upvision and downvision angles (see image above)?

Aerohead has listed vehicle approach and departure angles along with the inside angles between the front and rear wheels - see below (forgive me if I wrote them down wrong).

Front: 10 degrees min.

Rear: 16 degrees min.

In-between wheelbase: 10 degrees min.

I'm doing a few sketches and the upvision angle (so driver can see traffic signals) seems a bit low on my design. Just want to check with some standards.

H124 in this link:
https://law.resource.org/pub/us/cfr/...1100.2001.html

The math on this PDF is daunting.
https://www.google.com/url?sa=i&url=...AAAAAdAAAAABAD

Nice PDF paper on ergonomics:
https://www.google.com/url?sa=i&url=...AAAAAdAAAAABAV

__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html

Last edited by kach22i; 02-12-2021 at 05:50 PM..
  Reply With Quote
The Following User Says Thank You to kach22i For This Useful Post:
aerohead (02-12-2021)
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 02-12-2021, 06:02 PM   #2 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,181
Thanks: 19,612
Thanked 6,151 Times in 3,784 Posts
angles

Quote:
Originally Posted by kach22i View Post
SAE practices
https://www.researchgate.net/figure/...fig1_255700982


I know it's out there, but I cannot find it right now.

What are the recommend upvision and downvision angles (see image above)?

Aerohead has listed vehicle approach and departure angles along with the inside angles between the front and rear wheels - see below (forgive me if I wrote them down wrong).

Front: 10 degrees min.

Rear: 16 degrees min.

In-between wheelbase: 10 degrees min.

I'm doing a few sketches and the upvision angle (so driver can see traffic signals) seems a bit low on my design. Just want to check with some standards.

H124 in this link:
https://law.resource.org/pub/us/cfr/...1100.2001.html

The math on this PDF is daunting.
https://www.google.com/url?sa=i&url=...AAAAAdAAAAABAD

Nice PDF paper on ergonomics:
https://www.google.com/url?sa=i&url=...AAAAAdAAAAABAV
The SAE Handbook probably has the vision material. I'll look.
I think the approach, break-over, and departure angles are 16,10,10,and 10. I'll check.
The 'daunting' stuff is statistics. You might rearrange all the symbols and definitions.
Root Mean Square Error would be figured, then plugged in.
Go slow. Watch the brackets ( parentheses )
__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Old 02-12-2021, 06:03 PM   #3 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 18,363
Thanks: 5,037
Thanked 6,073 Times in 4,862 Posts
Off by one minute!

As a first approximation, measure the angle off the drawing. Estimating by eye-ball, it's ~30 degrees. Tell me how I did.

It's not like nobody's had the problem before: duckduckgo.com/?q=traffic+light+prism
__________________
.
The difference between science and screwin' around, is writing it down.
Adam Savage
_________________
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
aerohead (02-12-2021)
Old 02-14-2021, 03:29 AM   #4 (permalink)
Too many cars
 
Gasoline Fumes's Avatar
 
Join Date: Oct 2009
Location: New York State
Posts: 1,376

CRXFi - '88 Honda CRX XFi

Insight 256 - '00 Honda Insight
Team Honda
Gen-1 Insights

Insight 5342 - '00 Honda Insight
Team Honda
Gen-1 Insights
90 day: 65.78 mpg (US)
Thanks: 883
Thanked 645 Times in 383 Posts
Attached Thumbnails
Click image for larger version

Name:	blindspots.jpg
Views:	77
Size:	31.0 KB
ID:	30154  
__________________

  Reply With Quote
The Following User Says Thank You to Gasoline Fumes For This Useful Post:
aerohead (02-24-2021)
Old 02-14-2021, 09:27 AM   #5 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 3,726
Thanks: 36
Thanked 2,464 Times in 1,720 Posts
I love it, thank you gentlemen.

My trusty green 30/60 triangle that I've had for +40 years will come in handy once again.

I've got several adjustable triangles as well, and the drawing is in AutoCad already for when I have to get precise.
__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
  Reply With Quote
The Following User Says Thank You to kach22i For This Useful Post:
aerohead (02-24-2021)
Old 02-14-2021, 01:50 PM   #6 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 18,363
Thanks: 5,037
Thanked 6,073 Times in 4,862 Posts
3.9 out of 30? First approximation strikes again.
__________________
.
The difference between science and screwin' around, is writing it down.
Adam Savage
_________________
  Reply With Quote
Old 02-14-2021, 03:27 PM   #7 (permalink)
Long time lurker
 
AeroMcAeroFace's Avatar
 
Join Date: May 2019
Location: Uk
Posts: 114
Thanks: 55
Thanked 91 Times in 68 Posts
Remember People are differing heights

If you are designing a car, remember that people are different heights and some people like/need to be more reclined than others. The worst cars are the ones where the roof line is so low that you need to recline the seat just to fit. And then you are even further back, talking from experience from when I drove a Triumph Spitfire.

The opposite is true though sometimes you may not be able to see the hood at all due to sitting further back and lower down to get around the dashboard and wheel. Some cars are terrible for both taller and shorter people and some are good for both.
  Reply With Quote
The Following User Says Thank You to AeroMcAeroFace For This Useful Post:
aerohead (02-24-2021)
Old 02-14-2021, 03:47 PM   #8 (permalink)
Master EcoModder
 
freebeard's Avatar
 
Join Date: Aug 2012
Location: northwest of normal
Posts: 18,363
Thanks: 5,037
Thanked 6,073 Times in 4,862 Posts
In the SAE practices picture at the center of the seat adjustment range the bull's eye is called the H-point, or hip point. That's the thing every driver [probably] has in common.
__________________
.
The difference between science and screwin' around, is writing it down.
Adam Savage
_________________
  Reply With Quote
The Following User Says Thank You to freebeard For This Useful Post:
aerohead (02-24-2021)
Old 02-15-2021, 12:55 PM   #9 (permalink)
Master EcoModder
 
kach22i's Avatar
 
Join Date: Jul 2011
Location: Ann Arbor, Michigan
Posts: 3,726
Thanks: 36
Thanked 2,464 Times in 1,720 Posts
I'm not posting my design yet, as it's just for fun and is a work in progress.

However, my attempts to best the old Cab-Forward rules have had some disappointments.

When I draw a Le Mans Prototype style canopy it keeps getting pushed reward because of rules of thumb for vision angles, distance of driver's head to windshield (typically too much) and foot room better than that of a 1960's VW Beetle.

Measuring from front axle to head horizontal distance looks great at 3 feet, but needs to be 4-5 feet for foot room around the front wheel wells. This pushed the driver to the center area between the wheelbase and further back than I want.

Interesting article below that supports the study diagrams that I've been doing since the 1970's when I was but a child and teaching myself.

Cab-forward Design Saved Chrysler and Reshaped Urban Cars
https://medium.com/cardesignchronicl...s-e1a5620642dc

Quote:
In short, Chrysler managed to enlarge the cabin by making it move toward the car’s two other compartments, mostly the engine’s.
NOTE: My concept design has an electric motor at each wheel (inboard not hub-motor), and a rear mounted gas generator, the old center-line battery tray of former designs being replaced by a battery skateboard and or other low center of gravity and center of mass locations.

Where I'm at has gone full circle, two distinct paths.

Back to the clay car (fastback dune-buggy) I made with light blue pool noodle wheels - fits the aero-template and as posted over a decade ago in this forum.

And another path truer to the Le Mans Prototype inspiration that only fits a scaled down aero-template over the upper greenhouse teardrop canopy.

Circles within circles, I will probably put this down for a few weeks and go back the the Cab Over Engine (in look only) inspired concept that is in the spirit of the old Ford Model-T and Model-A, platforms that spawned; roadster, coupe, convertible, pickup truck and cargo van variants.

These head of a fish and body of a cheetah or bear designs are dear to my heart.
Attached Thumbnails
Click image for larger version

Name:	cab forward.jpg
Views:	73
Size:	49.0 KB
ID:	30155  
__________________
George
Architect, Artist and Designer of Objects

1977 Porsche 911s Targa
1998 Chevy S-10 Pick-Up truck
1989 Scat II HP Hovercraft

Chin Spoiler:
http://forums.pelicanparts.com/off-t...effective.html

Rear Spoiler Pick Up Truck
http://forums.pelicanparts.com/off-t...xperiment.html

Roof Wing
http://ecomodder.com/forum/showthrea...1-a-19525.html
  Reply With Quote
Old 02-24-2021, 12:20 PM   #10 (permalink)
Master EcoModder
 
aerohead's Avatar
 
Join Date: Jan 2008
Location: Sanger,Texas,U.S.A.
Posts: 12,181
Thanks: 19,612
Thanked 6,151 Times in 3,784 Posts
SAE angles

My dated SAE Handbook recommended :
* 16-degree approach
* 10-degree breakover
* 10-degree departure
If you 'slide' any of these angles along the ground plane until they contact the tire face, and they strike any part of the body when loaded to SAE test weight, you run the risk of a ground strike in daily operation.
Active air suspension can easily mitigate these issues. Best of both worlds.

__________________
Photobucket album: http://s1271.photobucket.com/albums/jj622/aerohead2/
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com