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07-24-2015, 09:27 AM
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#29
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Senior Member
Join Date: Jul 2012
Location: Fulltime, USA
Posts: 16,706
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Wind Gen. While Driving - Mounted in Rear Backwash
I wish you luck and look forward to test results.
If the gizmo was on my 40K lb rig at 65 mph, I don't know how any gain/loss could be measured unless always in dead calm air. Perhaps need a smaller, lighter test vehicle?
So what tools will you use measure gain/loss?
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07-24-2015, 11:09 PM
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#30
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Senior Member
Monaco Owners Club Workhorse Chassis Owner
Join Date: Aug 2002
Location: Clovis, CA, USA
Posts: 13,103
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I'm looking forward to your test results too.
Perhaps you could get 'Myth Busters' involved for a little financial support.
__________________
2004 Monaco La Palma 36DBD, W22, 8.1, 7.1 MPG
2000 LEXUS RX300 FWD 22MPG 4020 LBS
Criticism is easier than Craftsmanship
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07-25-2015, 02:21 AM
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#31
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Senior Member
Join Date: May 2014
Posts: 1,368
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We are all so lucky the most famous inventors were not as close minded as some of the comments make folks look here when asked to contribute to thoughtful exchange of knowledge. Just because (you) don't know the right answer, doesn't mean the next person's answer is wrong.
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Dan & Loretta, US Army Retired Aero Scout Pilot
2012 Fleetwood Providence 42P Class A/DP
Spartan Chassis, 8.9L Cummins 450HP
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07-25-2015, 12:21 PM
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#32
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Senior Member
Join Date: Feb 2010
Location: Sunnyvale, CA
Posts: 1,195
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So here's how to test the theory. And most folks can do this at home with little to purchase.
Ideally, we would do this with a hanging scale, but it CAN be done with a conventional scale and a tall chair.
You can use a cutting board to represent the flat plane that will be your motorhome body, and then you want to be able to tape/attach the small fan to one side of the cutting board (but you will want to be able to adjust the position of the fan on the cutting board).
You will need the large fan to create the relative wind/passage through the air.
Assemble this vertically with a vertical hanging scale, so you know what the weight is when everything is at rest.
Then turn on the big fan blowing down on the cutting board and see what the weight/drag is at "speed."
Now, move the small fan into position until it is consistently spinning in the downwash, and see what the weight(drag) is.
If you can get the small fan to spin without increasing the weight of the test rig, voila! "Free Energy!"
If the weight of the rig increases, it means you have increased drag and TANSTAAFL has come into effect.
Steve
__________________
The Green Machine -- 2000 Mountain High Coachworks Summit (Spartan chassis / Cummins ISC)
...and F-Troop: Fearghus, Fiona, and Frankie (Cairn Terriers)
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07-25-2015, 12:26 PM
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#33
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Administrator in Memoriam
Newmar Owners Club Retired Fire Service RVer's Spartan Chassis
Join Date: May 2000
Location: Newark, DE
Posts: 25,898
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Folks, some of the posts are getting a bit testy and off topic.
Let's stay on topic and keep our Mission Statement in mind;
Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Thanks!
__________________
Adios, Dirk - '84 Real Lite Truck Camper, '86 Wilderness Cimarron TT, previously 4 years as a fulltimer in a '07 DSDP
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07-28-2015, 06:53 PM
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#34
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Senior Member
Join Date: Dec 2014
Location: Warren, MI
Posts: 268
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Apparently folks are not observing the devices that empirically prove that the behind the vehicle generator does not work. The devices that I'm referring to are those little novelty boat propellers that are mounted to the hitch. Most of them that I've seen turn faster when the vehicle is parked and there is a crosswind, than when the vehicle is in motion. The bottom line; turbulent flow will not do the job because the wind energy doesn't come from a uniform direction.
__________________
Tom - KK8M -Warren, Michigan
MI Licensed Electrician, ISA Level 2 Certified I&C Tech, UL Certified PV Installer, Organic "Olla Irrigation" Gardener and bona fide Schlepper
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07-29-2015, 09:23 AM
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#35
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Member
Thor Owners Club Mid Atlantic Campers Ford Super Duty Owner
Join Date: Jul 2015
Posts: 60
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One thing to clarify: the airflow behind a MH will not be turbulent. The airflow will be fully separated and full of shedding vortices and other nasty unstable/unpredictable airflow patterns. Basically, chaos.
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2009 Four Winds Majestic 23A (ex-rental vehicle)
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07-30-2015, 10:12 PM
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#36
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Senior Member
Monaco Owners Club Vintage RV Owners Club
Join Date: Sep 2014
Posts: 993
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I commend the OP for sharing an idea.
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08-04-2015, 05:56 PM
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#37
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Senior Member
Join Date: Jul 2015
Location: Sandy, Utah
Posts: 196
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I looked into small wind gens and they really don't work that well. They don't handle gusts well. Sounds like your going solar so just spend your time researching and money on the right stuff, New battery bank, maybe a mppt controller. Also look into aftermarket alternators. Even your local alternator guy can rewind it to produce more amps. I can't see how it would be hard to add a isolator ( 100$) diverts alternator to the battery that needs it. Then run a wire under the body to the battery compartment. If you drive a bunch it may be worth it. But solar may be all you need.
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08-16-2015, 10:32 PM
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#38
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Junior Member
Thor Owners Club
Join Date: Mar 2012
Posts: 4
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Interesting concept for an RV. We have ram air turbines on commercial aircraft as an emergency power source when the other power sources fail. For example, the plane I fly is the Airbus 320. It has 3 AC generators powered by the main engines and the APU ( think genset but supplying air and elec). If all these fail, a little propeller drops out of the belly between the main landing gear. It drives a hydraulic pump to power the flight controls and can power another AC generator for electrical power. It is designed to work at speeds of 150 to 250 knots.
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2015 Thor Palazzo 36.2
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08-17-2015, 09:41 AM
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#39
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Senior Member
Outdoors RV Owners Club
Join Date: Dec 2014
Location: Nowhere, now here. Freedom!
Posts: 4,602
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The little propeller you speak of is in smooth air flow. There is likely almost no smooth air flow right behind an RV at highway speed.
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ORV 19B Full Timer from '15 to '20, '14 Ram 2500 Diesel and a GSD. Vancouver, WA
de K7NOL 146.52Mhz Safety? (CLICK ME!)
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08-18-2015, 06:31 AM
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#40
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Senior Member
Join Date: May 2014
Posts: 1,368
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Quote:
Originally Posted by redbusdriver
Interesting concept for an RV. We have ram air turbines on commercial aircraft as an emergency power source when the other power sources fail. For example, the plane I fly is the Airbus 320. It has 3 AC generators powered by the main engines and the APU ( think genset but supplying air and elec). If all these fail, a little propeller drops out of the belly between the main landing gear. It drives a hydraulic pump to power the flight controls and can power another AC generator for electrical power. It is designed to work at speeds of 150 to 250 knots.
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Redbusdriver,
Being an ATP you are well versed in the theory and application of aerodynamics.
When this concept was introduced, and even now it's so difficult for some to visualise how it is very possible and workable if the placement and size of the generators are just aft of the coaches top rear as we know the air that flows over the top and over the rear is near like it flows off the rear tip of a wing (airfoil).
And as I see it, with the fans not up directly in the main air flow, but mounted in a horizontal position facing up and approximately in the 12 to 24 inch range from the rear cap of the coach, there is no drag on the coach, and the air flow is changing towards the downward direction.
If this worked out, it would be as close as one could come to a free flow of air and not creating additional drag on the coach.
The biggest draw back is it would be ugly as all hell. So I'm sure it would never catch on.
__________________
Dan & Loretta, US Army Retired Aero Scout Pilot
2012 Fleetwood Providence 42P Class A/DP
Spartan Chassis, 8.9L Cummins 450HP
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08-18-2015, 09:33 AM
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#41
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Member
Thor Owners Club Mid Atlantic Campers Ford Super Duty Owner
Join Date: Jul 2015
Posts: 60
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Quote:
Originally Posted by Dtwallace
And as I see it, with the fans not up directly in the main air flow, but mounted in a horizontal position facing up and approximately in the 12 to 24 inch range from the rear cap of the coach, there is no drag on the coach, and the air flow is changing towards the downward direction.
If this worked out, it would be as close as one could come to a free flow of air and not creating additional drag on the coach.
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Mmmm...the flow over the rear cap really doesn't turn downward very much. There isn't much flow visualization for RVs, but there's quite a bit for big rigs and the airflow at the back should be similar.
__________________
2009 Four Winds Majestic 23A (ex-rental vehicle)
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08-18-2015, 12:02 PM
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#42
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Senior Member
Join Date: Sep 2012
Location: Tasmania now, USA/Canada/Alaska in April
Posts: 2,473
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When you get the generator working you could use it to feed an electrolysis cell to produce Browns Gas which you then feed into your engine to produce 25% more power and reduce fuel consumption by 35%. WIN-WIN-WIN situation.
__________________
Tony Lee - International Grey Nomad. Picasa Album - Travel Map
RVs. USA - Airstream Cutter; in Australia - MC8 40' DIY Coach conversion & OKA 4x4 MH; in Germany - Hobby Class C; in S America - F350 with 2500 10.6 Bigfoot camper
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