Proud new owner of a rpod 193 |
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GlueGuy
Senior Member Joined: 15 May 2017 Location: N. California Online Status: Offline Posts: 2629 |
Topic: Proud new owner of a rpod 193 Posted: 17 Jul 2020 at 5:21pm |
I don't think you can just take the frontal area; exposed or not. A significant portion (in fact, I think the majority) of the drag from trailer towing is the "suction" at the rear. That's why very aerodynamic things (e.g. airplanes) have the pointy part in the rear; it's to reduce the turbulence/suction/drag imposed by the back end of whatever it is.
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bp
2017 R-Pod 179 Hood River 2015 Ford F150 SuperCrew 4WD 3.5L Ecoboost |
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lostagain
Senior Member Joined: 06 Sep 2016 Location: Quaker Hill, CT Online Status: Offline Posts: 2587 |
Posted: 17 Jul 2020 at 6:14pm |
So a giant dunce cap on the back of the trailer is what I need? Too much time on my hands after returning from camping.
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Never leave footprints behind.
Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
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KerieG
Newbie Joined: 15 Jul 2020 Location: Portland, OR Online Status: Offline Posts: 8 |
Posted: 17 Jul 2020 at 9:09pm |
Wow thank you all for the explanations. We are still debating what to do. Its a chicken or egg thing. We have a Honda Pilot AWD with 5K towing capacity but I REALLY want that 193. But ugh this pandemic is both making me crazy and need to get out of this house but also the idea of trading in a vehicle right now is a pain in the butt.
Thank you all for the info! Lots to consider.
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Kerie
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 18 Jul 2020 at 5:06am |
Good for you in recognizing that the tow vehicle you have isn't up to towing that trailer. You have a decision to make, smaller trailer or bigger tow vehicle. I have a Highlander which is a good all around mid sized SUV with I think the same towing capacity as your Pilot. It gets used 90% of the time with no trailer behind it. Paired with the 179, it is a good match and provides what my wife and I find is an ideal size rig for two people. I wouldn't want anything bigger, and wasn't interested in owning a pickup truck again. Others have different needs, opinions, and budgets.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 18 Jul 2020 at 5:54am |
The reason aerodynamicists separate A and Cd is so they have separate shape and scale factors. That way they can do small scale wind tunnel testing of a shape and then scale it up to full size using the frontal area A. Since the tow vehicle and trailer share an air stream they effect each other, so, think of the rig as a single shape, It doesn't work to try to calculate their areas and drag coefficients separately. In this case the rig has a frontal area of say 55 square feet, the area of the trailer, which is larger than the tow vehicle. We don't know what the Cd is, which is why the manufacturer's 55 square foot restriction seems pretty bogus. The other reason is that just slowing down 5 mph has about the same impact as say the difference between 45 and 55 square feet would, everything else being equal. My guess is that the manufacturers just use A because it is fairly easy to measure. No one knows the Cd of each combination of tow vehicle and trailer. It allows them to place some kind of limit on the size of trailers being towed which they could use to protect themselves from litigation I suppose. I came up with the roughly 0.4 Cd for my rig by backing into it using fuel efficiency and rolling resistance numbers. But its a rough assumption, and similar to what other boxy vehicles are. The way to find out would be to do coast down testing. For me, that would only be worthwhile to test out the effect of a spoiler on the back of the SUV or removing the a/c or something like that. |
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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lostagain
Senior Member Joined: 06 Sep 2016 Location: Quaker Hill, CT Online Status: Offline Posts: 2587 |
Posted: 18 Jul 2020 at 8:17am |
Oh, heck, I'm just not going to think about it any more. My truck is balanced with the trailer to the point that it drives smoothly, has no tail wagging the dog issues, gets above average mileage, does fine with strong cross winds, and has plenty of reserve power. So I'll just keep plodding along with the cruise control set at 55, smiling as I drive, and arriving relaxed and ready to so some more serious relaxing at the destination.
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Never leave footprints behind.
Fred & Maria Kearney Sonoma 167RB Our Pod 172 2019 Ford F-150 4x4 2.7 EcoBoost |
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offgrid
Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290 |
Posted: 18 Jul 2020 at 10:01am |
Sounds like a good plan to me. Besides, while you're in CA you'll be driving at the legal speed limit for towing.
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1994 Chinook Concourse
1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold |
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KerieG
Newbie Joined: 15 Jul 2020 Location: Portland, OR Online Status: Offline Posts: 8 |
Posted: 01 Sep 2020 at 4:25pm |
Welp we did it! I think we're the first 193 owners in the PNW. Still working on upgrading the tow vehicle but I couldn't pass up the 193 that was on the lot. Super excited!
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Kerie
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StephenH
podders Helping podders - pHp Joined: 29 Nov 2015 Location: Wake Forest, NC Online Status: Offline Posts: 6288 |
Posted: 01 Sep 2020 at 4:44pm |
Congratulations and welcome! Just take it easy until you can upgrade. I hope you have many fun adventures and make many great memories with your new RP193.
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StephenH
Happy is the man that findeth wisdom,... ouR escaPOD mods Former RPod 179 Current Cherokee Grey Wolf 24 JS |
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KerieG
Newbie Joined: 15 Jul 2020 Location: Portland, OR Online Status: Offline Posts: 8 |
Posted: 01 Sep 2020 at 4:56pm |
Thanks!
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Kerie
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