Automotive Aerodynamics (video series)

[gumby79]

Just called darko they said :
"A full size pickup is to large for our tunnel as well as A2 wee have the same tunnel. The only tunnel that i know of that is large enoughfor an full size PU is Lockheed Martin in Atlanta Georgia for $3,000 per hour. This is ware GM took their production vehicles for Aero testing until they built their own WindTunnel. Darko test cell is 13'x9' " He asked for pics to do some math and figure out , if we take the wheels / tires off and put it on blocks , if it will fit. He said they have a 5000lbs limits per axel . He estimated 3-4 hr @500usd
Aerohead: if it fits without tires will this negate the reliability of the test?
Freebeard: the accuracy of a creek or stream would not be available the flow speed and volume is constantly changing and would negate any results as a steady speed could not be maintained this is why I was going the route of trying to get a model tested in a water channel where controlled conditions exist. But a good idea

[freebeard]

Speedboat on a lake? What kind of model can you build for the cost of one hour of tunnel time?

[gumby79]

Originally Posted by freebeard

Speedboat on a lake? What kind of model can you build for the cost of one hour of tunnel time?

2ft Of ice on the lake and no boat
Thank you for making my point this is exactly why I am looking to get a model tested
And this is the response from Darko
"David,

Your truck is too big for the Darko Tech tunnel.

After your call I talked with Gary at Aerodyn and A2. The A2 tunnel can accommodate your size but the weight is an issue. Call A2 for possibilities.

Good luck with the project.

Layne


Layne Christensen
Darko Technologies
766 Depot Drive Suite 1
Ogden, UT 84404
801-648-7016"
Too bad, I'm going to visit family in Ogden this summer

A2 Website said
A2 Wind TunnelA2 Wind Tunnel
"Balance: External 6 component load cell balance; 4200 lbs capacity."
My truck is 5520lbs 2wd full size


Aerohead this 27% is not a 1 best tank# if i go that route. ..
22.63 Best naked tank. Vs
27.33mpg best with cap =20.77% improvement ,still 41.54%
The 27% is based on thousands of real world miles including loaded excding10,000lbs at 62.5 ,3-4shift point, to75mph
I adjusted my "TV"cable to move my shift point downto 50mph Next trip to the VA 200mi ill run 55 and report

[freebeard]

Thank you for making my point this is exactly why I am looking to get a model tested

Happy to help.

[aerohead]

Originally Posted by gumby79

Just called darko they said :
"A full size pickup is to large for our tunnel as well as A2 wee have the same tunnel. The only tunnel that i know of that is large enoughfor an full size PU is Lockheed Martin in Atlanta Georgia for $3,000 per hour. This is ware GM took their production vehicles for Aero testing until they built their own WindTunnel. Darko test cell is 13'x9' " He asked for pics to do some math and figure out , if we take the wheels / tires off and put it on blocks , if it will fit. He said they have a 5000lbs limits per axel . He estimated 3-4 hr @500usd
Aerohead: if it fits without tires will this negate the reliability of the test?
Freebeard: the accuracy of a creek or stream would not be available the flow speed and volume is constantly changing and would negate any results as a steady speed could not be maintained this is why I was going the route of trying to get a model tested in a water channel where controlled conditions exist. But a good idea

*Yeah,without the wheels we'd have no clue as to what was going on.
*Tesla claims that the wheels on their S model contribute 20% of the overall drag.
*Hucho reported up to a 50% drag increase when wheels were added to low drag bodies.Here you can see what happened to Buchheim et al.' model at VW's tunnel

*Even if we had a wheels-off baseline on your truck,we wouldn't necessarily know if that relationship would hold as your streamlining brought the drag down.
--------------------------------------------------------------------------
CAR and DRIVER used to do fee testing which included SAE-protocol coastdowns at the Chrysler Proving Grounds near Ann Arbor,Michigan.They tested my Honda back in 1991 for $500.Since Csaba Csere left as Technical Editor,I'm unsure if any of the current staff are even acquainted with the procedure.C&D hasn't included coastdown data since the 1990s.
It wouldn't hurt to call them or email.They'd also do top speed on the Chrysler oval test track and we DO have a drag relationship for this where we could reverse-engineer drag coefficients.Gearing can be an issue though,as basically all USA vehicles are using gears are a speed governor.
*Forget about Bonneville.The rolling resistance is so high,and the 1-mile track to short to allow for terminal velocity.You'd never make it to top speed.
*I don't even think that the 2-mile at Mojave Airport,California is long enough.
*El Mirage Dry Lake isn't any better,and we have rolling resistance issues there as well.
*we amateurs have a tough time getting lab quality data.

[aerohead]

Originally Posted by gumby79

2ft Of ice on the lake and no boat
Thank you for making my point this is exactly why I am looking to get a model tested
And this is the response from Darko
"David,

Your truck is too big for the Darko Tech tunnel.

After your call I talked with Gary at Aerodyn and A2. The A2 tunnel can accommodate your size but the weight is an issue. Call A2 for possibilities.

Good luck with the project.

Layne


Layne Christensen
Darko Technologies
766 Depot Drive Suite 1
Ogden, UT 84404
801-648-7016"
Too bad, I'm going to visit family in Ogden this summer

A2 Website said
A2 Wind TunnelA2 Wind Tunnel
"Balance: External 6 component load cell balance; 4200 lbs capacity."
My truck is 5520lbs 2wd full size


Aerohead this 27% is not a 1 best tank# if i go that route. ..
22.63 Best naked tank. Vs
27.33mpg best with cap =20.77% improvement ,still 41.54%
The 27% is based on thousands of real world miles including loaded excding10,000lbs at 62.5 ,3-4shift point, to75mph
I adjusted my "TV"cable to move my shift point downto 50mph Next trip to the VA 200mi ill run 55 and report

I apologize for not following through,checking Hucho's Diesel vs Gasoline relationship / delta-CdA.Let me look into that.
I think we have 3-other caps similar to yours. Two have been CFD analyzed,and road tested.Let me try and dig out that data.
I'm limiting my trips to town,trying to be ready for Darko.It may be Saturday before I'm online again.
Enjoy that 27%.That's very sweet!

[freebeard]

6 months away? Sorry I won't be there. But I've worked out a plan to get my car back on the road. There's a lift reserved and I've already started on the payments.

The good news is it will have a 'mileage motor' stroker 1776 with dual Solex carbs. Given my bestest ever 37mpg tank, that should make 40mpg an attainable goal.

It sounds like you're down on Bonneville. For me it's that brine soup I drove through. Remember the coin-op car wash? I don't think my car recovered from that.

[gumby79]

I sent pictures that included the dimensions from my brake components to the ground and all the dimensions of the truck in a 360 ° fashion and Darkos answer was no a stock 91 Dodge d250 is too large for their wind tunnel. As to getting a Baseline the v1.2 cap weighs 35 pounds and can be handled by me or somebody smaller with ease the headache rack portion weight might be 50 pounds and I can have it stripped down to stock configuration in 15 minutes 30 minutes tops with an assistant make it 5 minutes as to the missing tires I can simulate with wood with the same spacing and protrusion but it still doesn't fit in the tunnel so back to models
Too bad they didn't ever put a Cummins in the Dakota, S-10, D-50, T100 then imy truck would fit. But I don't think it would be wise to put over a ton of payload into any of those small size trucks or pull a '85 F-250 4x4 on a 2000lbs trailer
thank you for your help looking forward to getting a 1:8 or whatever size he says will fit in his (grays garage) water Channel. printed with modifications that can be removed and or added to the stock configuration to go towards where I want to be
Small list aerodynamic parasites to address
Complete :
Aero cap

To do or develop :
Wrap around rain gutters (if testing shows that is worth the hours under the welding hood and in the paint booth).
Flat front/ recessed bucket halogen 55/65 watt headlights.
Almost vertical recess flat windshield.
Protruding bumpers( stick out past the body sides increasing frontal area in front and a giant scoop sticking out the side of the body and underbelly in the rear).
No air dam.
Excessive ground clearance (16"Under front bumper 21"rear of bed).
excessive rake .
Giant room for the tires and still have room for a cookie Fender Wells.
Lack of Front of tire spats and or full motion wheel enclosures for summers .

[freebeard]

Even if you could squeeze it in, the results skew off. The % blockage is important. If there isn't enough free air around the vehicle, it chokes down the flow and you get interference drag between the vehicle and walls.

Have you PM'd grays garage? His last post is still 04-07-2015 08:49 PM.

[gumby79]

Originally Posted by freebeard

Even if you could squeeze it in, the results skew off. The % blockage is important. If there isn't enough free air around the vehicle, it chokes down the flow and you get interference drag between the vehicle and walls.

Have you PM'd grays garage? His last post is still 04-07-2015 08:49 PM.

This is why I am patiently awaiting his response (and answering questions in the meantime) . To find out what size water chanal he has to find out what scale I can send ,to not my results. And why is the truck does not fit in the wind tunnels(perma link#53)
In permalink 29 He asks for 1/18-1/10 scale in( as these are the two most common Scale Models available from suppliers) permalink 32 Freebeard suggested 1/3 or 1/5( I like this idea closer to life test,closer to life results) in the videos it appears his water channel is approximately 4 foot by 4 foot and may handle a 1:5th Graysgarage.ca would know if his equipment can handle your suggestion.
Again I patiently await an answer

posted on his YouTube channel, I've posted here,and I've PMed. him. I have not been able to find an email/ or mailing address on his website. just checked still no contact information Help
Website

About Me - Graham Feltham - graysgarage.ca at Gray's Garage

I engaged in this lengthy conversation as a final attempt to get ahold of him. As stated in permalink #29 hes not on hear vary often. So my patience is necessary he has only posted 8times in the last year,2 of those are on this thred once in January and as you said in April. I'm a patient person. Give him time to respond. If I do not hear back from him.I will have to find other company to hire that has the appropriate air or water test equipment and I'LL call the 3D print shop in Butte Mt about a 1:10th -1:3 scale print. The reason for me trying this route is he specifically asks on his YouTube channel ,see video link in permalink #41, anybody's got anything like this they would like to have tested send him a model. This started out with. 1 question will a 1/43 scale model work in your water Channel? And thank you freebeard and Arrowhead both have very well answer the question for me. No it will not so now I have question number 2 what scale do I need to find. Seeing as this body style of Dodge pickup only has one size model currently commercially available . That I've been able to find so far and that is a 1/43 scale ,however ,that won't work, as per permalink #32 and 36