Originally Posted by Alumineer
Take your time to read this thesis
before you do a bunch of experimenting.
Basically, it's all been done before and the theory is clear and well understood. The operative principles of trailer sway elimination are:
- keep your loads close to the center of the trailer
- keep your tongue weight in a reasonable range
- keep your speed down.
But, you seem to be bent on pushing the envelope on all three fronts. Good luck with that. If I was your wife I'd whack you over the head with the bicycles until you stopped.
I disagree that the OP is pushing the envelope on those 3.
Because the OP has not weighed his HW - there is still no direct evidence that his HW is low, other than presumptions of same by others on here based on his sway issue, which could've been due to many other factors.
I would bet that the HW was within 10-15% - even with the bikes on back, once he does weigh it, since the LP tanks & WD/SC hitch alone would counteract it, & AS allows some bikes carried on the rear.
He has stated that he kept his speed down, & a bike rack & 2-4 bikes are allowed per his AS manual (I don't recall if it said 2, 3 or 4 bikes).
While useful to some extent, this Grad School Thesis paper involves some significant differences from USA/N.American trailers & tow vehicle & their WD/SC hitches.
1st, is that our WD hitches aren't used in the UK/Euro area, because they were outlawed in most of the area back in the 1960's in a protectionist move by their major trailer chassis maker when they were approached by a US WD hitch maker/inventor suggesting that they strengthen their frames to be able to use WD hitches & build bigger/better trailers (search for the story if you're interested. Therefore....
2nd - All UK/Euro trailers are (still) built smaller, lighter & narrower, than are most US/NA trailers - so they have different dynamics than those here. And more significantly ....
3rd - All UK/Euro trailers - including the ones in this paper's study - are towed on a bare ball & using other types of less effective sway control than we use here in the US/NA.
However, there was a similar & more detailed study done for US-DOT in the late 1960's or early 70's on the subject & other matters relevant to towing, which I've seen on the net. Unfortunately, that bookmark & pdf download is on my old "dead" laptop, so I'll leave that to your own devices to find it (it may have involved CanAm's Andy T's Dad IIRC).
Also, what pteck is saying above, is to use counter-weighting at the front of the trailer to maintain the the HW at 10-15% ot GTW - NOT as a dynamic counterbalance as dkottom took his comment.
While it makes sense to do that if you're rear weight inside or outside the trailer box/frame (e.g.: rear bathrooms, queen & king size beds with storage under them, all that stuff we put in our trailers' "trunk"/storage area back there) is causing it to be less that 10-15% - the better solution is to keep the rear weight less than where counter-weighting is needed.
In many cases, the addition of big LP tanks, battery boxes, power jacks, WD/SC hitches, etc. to the A-frames, tends to put the HW at more than 10-15% - so counter-weighting at the rear isn't necessarily a bad idea, bringing the HW back within 10-15%, & perhaps helping with the TV's HW & Rear Axle Wt. limits.
In our case, our factory dry 2680# & 275" HW 1960
Avion T20 (dry/empty/no options I assume) - went to 542# (per my Sherline), due to the addition of 2x 30# LP tanks, Tekonsha RF Brake Controller mounted on a 15"x18"x3/32" steel plate (for clearance), & the 160# Hensley Cub + the change from the factory 20 gal aluminum pressure fresh water tank to a 27-30 gal. poly tank, pump & battery/box at the front of the trailer/dinette. So clearly putting +/- 200# at the rear of my trailer will still leave me at 342# & within 10-15% HW (assuming a 100% counter-weight effect).
So there are cases where counter-weighting will work to a positive benefit.
AS & all of the other trailer mfgrs. are "breaking the rules" laid out by the writer of the thesis above, by placing bathrooms & tanks, storage bins & trunks etc., beds & furniture etc., at the far rear of their trailers - as well as making trailers with huge long rear overhangs.
So to assume it's inherently dangerous to add a properly designed for trailer use & appropriately secured/stabilized bike rack at a position on the rear of the trailer, which is loaded within the limits of the rack & trailer's mfgr's. documentation for same - is just not correct.
Many of you wouldn't give a second thought to adding a non-mfgr. or non-mfgr.-recommended aftermarket item to your cars or trucks, but some here will call foul for using a non-AS or non-AS-recommended bike rack - even when the OP has stated that he has or will attend to all of the weight & stabilization parameters of the AS.
AS has a vested interest in only recommending their racks & accessories, called profit - as well as the cost/time limitations on testing each & every rack or accessory available out there. Instead, the recommend theirs & 1 or 2 others (maybe), & the owner is left to match the parameters of those items design.
For example, Porsche has a whole line of their
accessories for the Cayenne which we are looking at for our TV, but that doesn't mean that I can't safely use my Yakima Swing Daddy bike rack on it's hitch, nor other non-Porsche roof rack mounted bike, ski, surfboard racks or cargo boxes on its roof either.
If your AS is under warranty & you want to play it safe, then by all means make your choice to only use AS products, but don't assume that other products can also be safely used. If an AS/Fiamma hitch is allowed to carry 2, 3 or 4 bikes per AS, then another type/brand can likewise safely do so, as long as it is properly mounted & stabilized to perform in the same way.
I wonder how many AS buyers out there would suddenly dump their current favorite WD/SC hitch, if AS/Thor were to suddenly strike a deal with Hensley &/or PP to ONLY recommend that hitch for use on their trailers? Would we suddenly have a whole new crop of Hensley/PP devotees? .... or would we see most folks sticking with other hitch choices? I suspect the latter.
So don't unjustly harrang the OP for using another bike rack, but instead just offer the parameters to to make it safe, because there is nothing inherently unsafe about using another non-AS bike rack to carry the same number of bikes.
If anything, perhaps the AS/Fiamma bike racks are not all that great nor strongly made, because at least one photo erlier in this thread showed that the AS recommended Fiamma bike rack BROKE & FAILED while carrying bikes! And yet that is completely ignored by the disciples of them for some reason.
Lastly, as to the dynamic loading & whether counter-balancing
weights would be effective or now in damping any natural sway - there are high rise building around which are using dynamic counter-balance systems to dampen, counteract & eliminate seismic (earthquake) movement.
While that sort of computerized dynamic system is beyond application to our trailers, it is likewise not absolutely correct to say that there can be no
counter-balancing effect at all by careful placement of what is stowed inside, on top of & outside/behind our trailers.
Pilots also have to do weight & balance calculations & adjust loads & placement accordingly, in order to keep their aircraft in balance & controllable in 3-axes. Certainly we can do so in 2-axes.
Most of you out there do strategically place cargo in your trailers, without them becoming a Lucy "Long Long Trailer" disaster, so this should be no different if done properly.
Keep Cool in the Heat & Cheers!