Tongue weights at which sway has occurred? - R-pod Owners Forum

Offgrid, Yes to all questions.

Mike Carter
2015 178
" I had the right to remain silent, I just didn't have the ability."

Jato was good enough to remind me that he had already shared his sway data. His 177 had dual batteries and a single propane on the tongue and a full fresh water tank aft when he experience significant sway at only 40 mph. I back calculated his tongue weight to be right about 10% at that point.

I've added his data to the list:

7%? (guy on physics forum) catastrophic sway, trailer stops swaying only when it hits back corner of TV

9.5% (mcarter's 178) sway causes anxious moments but not catastrophic.

10% (jato's 177 significant sway at 40 mph brought under control)

11%?(Glueguy's Pacheco pass 172 guy) "a little squirrely"

12% (lostagain's 177) no sway

13-15% (offgrid's and Glueguy's 179's), no sway.

This is painting an interesting picture I think. It seems like the rPods are subject to sway at a bit higher tongue weight percentages than the generally accepted 10% number.

Of course, there are plenty of other factors involved that will help to determine if sway will actually start (side wind from semi's, downhill braking, trailer tire pressures, etc, and even more factors as to whether the sway is damped out before it gets significant (weight and wheelbase of tow vehicle, tow vehicle tire pressures, antisway systems, etc. It's a complex phenomenon and from what I've read so far not as well understood from a mechanical engineering perspective as you'd think.

Still, I think this information at least gives us an idea when you would want to start being concerned about it, probably anything below 11% tongue weight or so. By 10% sway is happening is some cases.

That tells me not to try to move very much weight aft in my 179, if any. The 179's lose about 3.5% of tongue weight moving 30 gal of fresh water to 30 gal of gray water, and I'm currently right at 15% with the fresh tank loaded. that would put me at about 11.5% if the gray tank was filled instead, about as low as I feel comfortable going.

Thanks everyone.

1994 Chinook Concourse
1995 RV6A Experimental Aircraft
2015 Rpod 179 - sold

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mcarter Members Profile Send Private Message Find Members Posts Add to Buddy List podders Helping podders - pHp Joined: 07 Apr 2016 Location: Greenbrier, TN Online Status: Offline Posts: 3419	Topic: Tongue weights at which sway has occurred? Posted: 04 Nov 2018 at 2:33pm
	Offgrid, Yes to all questions.
	Mike Carter 2015 178 " I had the right to remain silent, I just didn't have the ability."

offgrid Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290	Posted: 04 Nov 2018 at 3:26pm
	thanks mcarter. The listed empty weights for the 2o15 178 are 257 tongue and 2535 trailer, so right at 10.1% tongue wt. All your added stuff should be about 390 lbs and it I estimated distances right about 20 additional lbs on the tongue. So, you should have been at about 9.5% on the tongue. So now we have a few data points for rPod trailer sway susceptibility: 7%? (guy on physics forum) catastrophic sway, trailer stops swaying only when it hits back corner of TV 9.5% (mcarter's 178) sway causes anxious moments but not catastrophic. 11%?(Glueguy's Pacheco pass 172 guy) "a little squirrely" 12% (lostagain's 177) no sway 13-15% (offgrid's and Glueguy's 179's), no sway. So far this is supporting maybe 11% as a min safe tongue wt rather than the "standard" 10% . Lets see if anyone else has any info.
	1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold

offgrid Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Jul 2018 Online Status: Offline Posts: 5290	Posted: 05 Nov 2018 at 12:54pm
	Jato was good enough to remind me that he had already shared his sway data. His 177 had dual batteries and a single propane on the tongue and a full fresh water tank aft when he experience significant sway at only 40 mph. I back calculated his tongue weight to be right about 10% at that point. I've added his data to the list: 7%? (guy on physics forum) catastrophic sway, trailer stops swaying only when it hits back corner of TV 9.5% (mcarter's 178) sway causes anxious moments but not catastrophic. 10% (jato's 177 significant sway at 40 mph brought under control) 11%?(Glueguy's Pacheco pass 172 guy) "a little squirrely" 12% (lostagain's 177) no sway 13-15% (offgrid's and Glueguy's 179's), no sway. This is painting an interesting picture I think. It seems like the rPods are subject to sway at a bit higher tongue weight percentages than the generally accepted 10% number. Of course, there are plenty of other factors involved that will help to determine if sway will actually start (side wind from semi's, downhill braking, trailer tire pressures, etc, and even more factors as to whether the sway is damped out before it gets significant (weight and wheelbase of tow vehicle, tow vehicle tire pressures, antisway systems, etc. It's a complex phenomenon and from what I've read so far not as well understood from a mechanical engineering perspective as you'd think. Still, I think this information at least gives us an idea when you would want to start being concerned about it, probably anything below 11% tongue weight or so. By 10% sway is happening is some cases. That tells me not to try to move very much weight aft in my 179, if any. The 179's lose about 3.5% of tongue weight moving 30 gal of fresh water to 30 gal of gray water, and I'm currently right at 15% with the fresh tank loaded. that would put me at about 11.5% if the gray tank was filled instead, about as low as I feel comfortable going. Thanks everyone.
	1994 Chinook Concourse 1995 RV6A Experimental Aircraft 2015 Rpod 179 - sold