LocostUSA.com

Learning how to build Lotus Seven replicas...together!
It is currently August 19, 2018, 9:00 am

All times are UTC - 5 hours [ DST ]




Post new topic Reply to topic  [ 38 posts ]  Go to page 1, 2, 3  Next
Author Message
 Post subject: interesting aero
PostPosted: February 18, 2018, 12:30 pm 
Offline
User avatar

Joined: March 30, 2011, 7:18 am
Posts: 1395
Location: central Arkansas
This turned up while smurfing for 7 pictures:

http://www.racedandrallied.com/performa ... ally-built

The builder added a number of aero tweaks that mostly seem intended to reduce cockpit turbulence. The windshield sits back close to the seat, the sides of the frame are high, and there's a horizontal deflector at the top of the side. There's a boxlike deflector behind the front wheel, and one just ahead of the A-arms, tied into the winglets.

I also note the windshield has a bit more rake than normal, and it's formed from two round tubing hoops instead of the usual C channel. I expected to see triangular Lexan windows there, but it looks like he didn't bother. It looks like the windshield is held in a 360 degree hoop with mounting legs. I can't see a good reason for that, unless the windshield is removable for track events. The back of the cowl seems to be pulled into a more or less rectangular shape, which let him use a straight bottom on the glass.

Thread with Locost CFD streamlines: https://www.locostusa.com/forums/viewto ... 23&t=13379


Attachments:
x4.jpg
x4.jpg [ 137.35 KiB | Viewed 982 times ]
x2.jpg
x2.jpg [ 140.71 KiB | Viewed 982 times ]
x1.jpg
x1.jpg [ 85.64 KiB | Viewed 982 times ]
Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 19, 2018, 1:29 am 
Offline
User avatar

Joined: April 26, 2008, 6:06 pm
Posts: 2956
Location: Under the weather. (Seattle)
It does kill some of the 'traditional' looks, but seems like it should be functional. If nothing else, they're definitely interesting solutions. I kind of like it.

_________________
-Justin

Also follow my build on blogspot, tumblr, or instagram and twitter (GarageOdyssey)


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 19, 2018, 8:14 am 
Offline
User avatar

Joined: September 22, 2005, 8:12 am
Posts: 1470
Location: 4AGE in S.E. Michigan
Should be functional if the intent is to reduce the max top speed!
Dave W


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 19, 2018, 12:56 pm 
Offline
User avatar

Joined: October 24, 2008, 2:13 pm
Posts: 3532
Location: Carlsbad, California, USA
It's hard to guess at the builders intent, but the nearly flat pieces on the cockpit sides would make nice arm rests if they were padded. Also,they could be to prevent heat radiating up from the exhaust system, or to deflect stones away from the driver. I'm sure there are other possibilities too.

On an intuitive level, the only thing that looks like it would cause real trouble are those vertical pieces from the winglets. I'm seeing nothing but turbulence, hence drag, from those. You've got to test this stuff to know, however. Obviously, I could be wrong.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 19, 2018, 2:01 pm 
Offline
The voice of reason
User avatar

Joined: January 10, 2008, 4:47 pm
Posts: 7548
Location: Massachusetts
It looks like part of what's going on is he is trying to vent the engine compartment and make his radiator and cooling more efficient. it's putting low pressure areas where there are side opening form the engine compartment....

It looks like he lives in a warm/desert area.

_________________
Marcus Barrow - Car9 an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 19, 2018, 2:21 pm 
Offline
User avatar

Joined: April 26, 2008, 6:06 pm
Posts: 2956
Location: Under the weather. (Seattle)
davew wrote:
Should be functional if the intent is to reduce the max top speed!
I wouldn't be too sure about that.

_________________
-Justin

Also follow my build on blogspot, tumblr, or instagram and twitter (GarageOdyssey)


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 19, 2018, 3:26 pm 
Offline

Joined: June 5, 2016, 7:03 am
Posts: 210
Location: ontario
[quote="TRX"]This turned up while smurfing for 7 pictures:

http://www.racedandrallied.com/performa ... ally-built

An attractive rig. Some of the work I don't fully understand, like the front winglets. It looks that the aluminum "elbow guards" (my words) are designed to protect the driver from gravel stones and other debris thrown by the front wheels. The deflectors behind the wheels? I assume that the idea is to improve air flow on each sides of the vehicle. I guess many people would think all this was a good idea. I am not sure that (if I build a third seven) I will do any of that. On the issue of better protection for the driver and passenger for instance I would consider clam shell fenders or even better fabricate my own fixed front fender system that would take into consideration all the issues that this builder was attempting to address. I am thinking of fuller bodied sevens à la Donkervoort.


Attachments:
donkervoort.jpg
donkervoort.jpg [ 8.58 KiB | Viewed 854 times ]
Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 20, 2018, 3:12 pm 
Offline
User avatar

Joined: March 30, 2011, 7:18 am
Posts: 1395
Location: central Arkansas
Wossname's CFD plot of 7 airflow around the cockpit shows some of the streamlines curling up and over the sides of the cockpit. The "armrests" (not a bad idea...) would move the air stream a bit further away from the driver's head.

Likewise, the box structures behind the wheels look like they're intended to deflect air away from the sides.

The winglets and vertical pieces at the nose do look more like cooling aids, though.


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 20, 2018, 3:44 pm 
Offline
User avatar

Joined: October 23, 2010, 2:40 am
Posts: 1040
Also note the grill screen on the scuttle in front of the windshield. Possible air inlet (engine intake?) that takes advantage of the higher pressure in front of the windshield.

_________________
Cheers, Tom

My Car9 build: viewtopic.php?f=35&t=14613
"It's the construction of the car-the sheer lunacy and joy of making diverse parts come together and work as one-that counts."

Ultima Spyder, Northstar 4.0, Porsche G50/52


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 20, 2018, 4:03 pm 
Offline
User avatar

Joined: April 26, 2008, 6:06 pm
Posts: 2956
Location: Under the weather. (Seattle)
seattletom wrote:
Also note the grill screen on the scuttle in front of the windshield. Possible air inlet (engine intake?) that takes advantage of the higher pressure in front of the windshield.
Good eye.

Image

_________________
-Justin

Also follow my build on blogspot, tumblr, or instagram and twitter (GarageOdyssey)


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 21, 2018, 9:25 am 
Offline
User avatar

Joined: September 22, 2005, 8:12 am
Posts: 1470
Location: 4AGE in S.E. Michigan
"Wossname's CFD plot of 7 airflow around the cockpit shows some of the streamlines curling up and over the sides of the cockpit. The "armrests" (not a bad idea...) would move the air stream a bit further away from the driver's head."
The trouble is that the arm rest would increase the air flow outboard around the rear fender, making the outboard fender appear wider to the air stream which would add to the drag vs over and inboard flow. Also there is a substantial net affect of increasing frontal area around the fender including the other additional structures.
It there is an over heating issue a small vertical lip in front of the side panel opening, would cause a low pressure area behind opening, Vs all the induce drag of the pod added to the sides of the vehicle.
None of these changes are simple form radius or bevel changes. when you start hanging stuff out in the air stream, it is going to increase the drag.
Dave W


Attachments:
streamlines2_front_iso.JPG
streamlines2_front_iso.JPG [ 86.59 KiB | Viewed 770 times ]
Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 21, 2018, 12:40 pm 
Offline
User avatar

Joined: April 26, 2008, 6:06 pm
Posts: 2956
Location: Under the weather. (Seattle)
davew wrote:
when you start hanging stuff out in the air stream, it is going to increase the drag.
Often, but not always.

_________________
-Justin

Also follow my build on blogspot, tumblr, or instagram and twitter (GarageOdyssey)


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 21, 2018, 2:16 pm 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 4653
Location: West Chicago,IL
It shouldn't be too hard to mock up those arm rests in cardboard and duct tape. Then go for a ride to see if there is any benefit. My gut feel is, maybe as much as a 50% reduction in dis-comfort level. Not gone, but an improvement.

That might be why half-doors are such a thing in the UK.

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my active Cushman Truckster resurrection log: over HERE
or my archival Locost build log: over HERE


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 22, 2018, 8:06 am 
Offline
User avatar

Joined: September 22, 2005, 8:12 am
Posts: 1470
Location: 4AGE in S.E. Michigan
Chuck
You are right about the half doors. It is surprising how much air is re-directed rearward over the fender, Vs into the cockpit area. My half doors are on 90% of the time. Only when it is extremely hot do they get removed. The nice part about half doors, is if you leave early in the morning and later it gets hot out on the road, you can remove them, because the half door will actually fit in the trunk area.
Dave W


Top
 Profile  
Reply with quote  
 Post subject: Re: interesting aero
PostPosted: February 22, 2018, 9:50 am 
Offline
User avatar

Joined: July 17, 2008, 9:11 am
Posts: 4653
Location: West Chicago,IL
Dave, you guys with trunks make me laugh :lol:

_________________
Chuck.

“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my active Cushman Truckster resurrection log: over HERE
or my archival Locost build log: over HERE


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 38 posts ]  Go to page 1, 2, 3  Next

All times are UTC - 5 hours [ DST ]


Who is online

Users browsing this forum: No registered users and 3 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
POWERED_BY