Armed Polite Society

Main Forums => The Roundtable => Topic started by: Ben on May 25, 2013, 02:39:02 PM

Title: Tailgate Up or Down?
Post by: Ben on May 25, 2013, 02:39:02 PM
Interesting study by GM. I've never driven with the tailgate off or down outside of hauling stuff because I never figured any fuel savings would be all that great. The tailgate net thing is interesting.

http://www.foxnews.com/leisure/2013/05/20/tailgate-up-or-down-gmc-solves-age-old-pickup-truck-mystery/?intcmp=features
Title: Re: Tailgate Up or Down?
Post by: Jamisjockey on May 25, 2013, 02:43:46 PM
I usually have a shovel back there....up it is.....would rather not FOD out the cars behind me....
Title: Re: Tailgate Up or Down?
Post by: Gewehr98 on May 25, 2013, 03:00:15 PM
Doesn't anybody watch MythBusters? 

They tested this one out years ago.

Results:  Better aerodynamics with tailgate up.
Title: Re: Tailgate Up or Down?
Post by: 230RN on May 25, 2013, 04:24:18 PM
Akin to the question of does "drafting" a vehicle increase, decrease, or not affect the power/mileage of the front vehicle.  I suppose by now someone's answered that one.

I remember a while ago this question generating three or four pages of .45 v .9-type "discussion."

Title: Re: Tailgate Up or Down?
Post by: Waitone on May 25, 2013, 04:24:33 PM
Why is this nooze?  Next thing you'll hear is a recently washed car drives better than a dirty car.
Title: Re: Tailgate Up or Down?
Post by: Fly320s on May 25, 2013, 04:28:41 PM
Why is this nooze?  Next thing you'll hear is a recently washed car drives better than a dirty car.

But not better than a dimpled car.
Title: Re: Tailgate Up or Down?
Post by: birdman on May 25, 2013, 05:01:59 PM
Akin to the question of does "drafting" a vehicle increase, decrease, or not affect the power/mileage of the front vehicle.  I suppose by now someone's answered that one.

I remember a while ago this question generating three or four pages of .45 v .9-type "discussion."



For the vast majority of combinations, drafting improves the aerodynamics of both.  But definition, the rear vehicle is experiencing a lower average air velocity, and in most cases, the front vehicle sees a reduction in drag due to a higher pressure at the rear.
Title: Re: Tailgate Up or Down?
Post by: BlueStarLizzard on May 25, 2013, 05:05:44 PM
Why is this nooze?  Next thing you'll hear is a recently washed car drives better than a dirty car.

My car must drive really crappy then...

=D
Title: Re: Tailgate Up or Down?
Post by: Northwoods on May 25, 2013, 05:21:28 PM
For the vast majority of combinations, drafting improves the aerodynamics of both.  But definition, the rear vehicle is experiencing a lower average air velocity, and in most cases, the front vehicle sees a reduction in drag due to a higher pressure at the rear.

That's what she said ...
Title: Re: Tailgate Up or Down?
Post by: Devonai on May 25, 2013, 08:38:08 PM
Be sure to use a medium viscosity lubricant!
Title: Re: Tailgate Up or Down?
Post by: BlueStarLizzard on May 25, 2013, 09:33:45 PM
Be sure to use a medium viscosity lubricant!

 ;/

The 'P' stands for 'polite', not 'pervert'.

Although, considering this crowd, maybe we could use a name change.

Title: Re: Tailgate Up or Down?
Post by: Devonai on May 25, 2013, 10:13:50 PM
I'm sorry!   =(  I can delete the offending comment if you want.  I will be more careful in the future.
Title: Re: Tailgate Up or Down?
Post by: BlueStarLizzard on May 25, 2013, 10:19:22 PM
I'm sorry!   =(  I can delete the offending comment if you want.  I will be more careful in the future.

Twas a jest.
Title: Re: Tailgate Up or Down?
Post by: Gewehr98 on May 25, 2013, 10:51:50 PM
Armed Promiscuous Society. 

I like it!
Title: Re: Tailgate Up or Down?
Post by: BlueStarLizzard on May 25, 2013, 11:01:50 PM
Armed Promiscuous Society. 

I like it!

No, no, no. 'promiscuous' is to much a mouthful and has the wrong connentation. 'pervert' more accuratly discribes the majority of the membership.
Title: Re: Tailgate Up or Down?
Post by: zxcvbob on May 25, 2013, 11:02:01 PM
Interesting study by GM. I've never driven with the tailgate off or down outside of hauling stuff because I never figured any fuel savings would be all that great. The tailgate net thing is interesting.

http://www.foxnews.com/leisure/2013/05/20/tailgate-up-or-down-gmc-solves-age-old-pickup-truck-mystery/?intcmp=features

I read a patent a couple of years ago about reducing drag with a half tonneau cover (just the back half.) it's supposed to work better than a full cover.  The counter-intuitive part is you leave the front of the the box created by the cover and bed and tailgate *open* (and the tailgate closed.)  I have a scrap of plywood in the garage that looks about the right size but I haven't tried it yet -- would have been handy a couple of weeks ago when I took a long trip.  As an added bonus, it'll keep the rain off my luggage thrown in the back.  
Title: Re: Tailgate Up or Down?
Post by: French G. on May 25, 2013, 11:09:33 PM
So if I get arrested for bump drafting on the interstate can I get out of it by pleading that I was doing it for the environment? Not that I would ever initiate contact with another car, that'd be just wrong.  :angel:
Title: Re: Tailgate Up or Down?
Post by: Northwoods on May 26, 2013, 12:09:38 AM
No, no, no. 'promiscuous' is to much a mouthful and has the wrong connentation. 'pervert' more accuratly discribes the majority of the membership.

And some of us might fit the perv lable while being monogamus >:D.
Title: Re: Tailgate Up or Down?
Post by: BlueStarLizzard on May 26, 2013, 12:20:41 AM
And some of us might fit the perv lable while being monogamus >:D.

That too.
Title: Re: Tailgate Up or Down?
Post by: lupinus on May 26, 2013, 08:48:45 AM
Perverted thread drift, as APS tradition
Title: Re: Tailgate Up or Down?
Post by: birdman on May 26, 2013, 10:06:09 AM
I read a patent a couple of years ago about reducing drag with a half tonneau cover (just the back half.) it's supposed to work better than a full cover.  The counter-intuitive part is you leave the front of the the box created by the cover and bed and tailgate *open* (and the tailgate closed.)  I have a scrap of plywood in the garage that looks about the right size but I haven't tried it yet -- would have been handy a couple of weeks ago when I took a long trip.  As an added bonus, it'll keep the rain off my luggage thrown in the back.  

Not surprising.  The tailgate up reduces drag (for modern trucks) by creating a vortex area of higher pressure, but low flow that enables the air going over and around the cab to flow smoothly back (around the vortex) and not impact the tailgate.  A back-half tonneau cover would do something similar, by both creating the high pressure zone in the front of the bed (possibly at lower flow than having the whole bed open), while minimizing area for any bleed flow to hit.

The best would obviously be a cap that slopes downward at approx a 15deg angle, then has a K-tail at the rear to create a vortex trail to reduce wake drag.

A K-tail is the slope plus moderate flip-up seen at the back of hatchbacks designed for mileage, like a Prius.  What it does is truncate an ideal teardrop-end but create a high pressure vortex that virtually recreates it and reduces wake drag.
http://en.wikipedia.org/wiki/Kammback

Also the logic of boat-tail bullets :)
Title: Re: Tailgate Up or Down?
Post by: zahc on May 26, 2013, 10:19:19 AM
No, no, no. 'promiscuous' is to much a mouthful and has the wrong connentation. 'pervert' more accuratly discribes the majority of the membership.

The correct rendering is "preverts". As in "deviated preverts".
Title: Re: Tailgate Up or Down?
Post by: Tallpine on May 26, 2013, 10:22:34 AM
So maybe now they will figure out how to build a tailgate latch that lasts more than a few years  ;/
Title: Re: Tailgate Up or Down?
Post by: Waitone on May 26, 2013, 03:54:09 PM
Quote
So if I get arrested for bump drafting on the interstate can I get out of it by pleading that I was doing it for the environment?
Years ago Richard Petty got hacked off at a driver driving too slowly in the left lane.  So he proceeds to act like a NASCAR driver and bumped her.  The judge wasn't impressed and it terminated his promising political career.
Title: Re: Tailgate Up or Down?
Post by: 230RN on May 31, 2013, 07:49:57 PM
And some of us might fit the perv lable while being monogamus >:D.

<trivia>

Quote
Higamus hogamus,
Woman's monogamous.
Hogamus higamus
Man is polygamous.

Ross Barnett in "The Marriage-Go-Round" by Leslie Stevens

</trivia>

Title: Re: Tailgate Up or Down?
Post by: RoadKingLarry on May 31, 2013, 11:05:40 PM
Be sure to use a medium viscosity lubricant!

That's what she said ...