COBRA Anti-Sway Coupler

Tony wrote on 9/4/2020 1:31 PM:
Thread Drift on RAS, who would've thunk.

Solid advice from Mark Mocho. I've towed a lot of mostly new-ish Cobra trailers around the country at Speed Limit+5 but never more than 80 MPH (I'm looking at you Texas and Utah). None of them that I recall had the anti-sway coupler and none of them ever showed the slightest tendency to sway behind my 3.6L Subaru Outback.

I talked briefly with Keith Essex last year about his experiences towing his ASH
32Mi behind a smallish SUV. He said the Cobra coupler made the combination steady.
That's a two-seater, of course, so a more difficult task, but it shows it works.
Your car/combination may or not need the assistance of the coupler.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

I have lived in California for 35 years. I am unaware of this "I can't drive 55" while towing law/suggestion.

There is that pesky small print on the white highway signs that start with '55'.

They seem to be posted in pairs. One for trucks, one for towing.

I have lived in California for 35 years. I am unaware of this "I can't drive 55" while towing law/suggestion.

There is that pesky small print on the white highway signs that start with '55'.

They seem to be posted in pairs. One for trucks, one for towing.

There are a number of threads on RAS concerning vehicle size vs sway potential. The gist seems to focus on mass and wheelbase of the tow vehicle (more mass, longer wheelbase preferred), fore/aft loading of the trailer (10% of trailer weight on tongue), tire size/construction (radial vs. bias ply) and tire pressure for both the trailer and vehicle (higher pressure = stiffer sidewalls).

Of course, since this is RAS, assorted self proclaimed "engineers" will come out of the woodwork arguing the exact opposite of any of these principles.. Using their logic, the "ideal" tow vehicle is a motorized skateboard with silly-putty tires and the ass end of the trailer loaded down. But with vortex generators. Please ignore these people.

On Friday, September 4, 2020 at 8:43:34 AM UTC-7, Jonathan St. Cloud wrote:
On Thursday, September 3, 2020 at 9:45:25 PM UTC-7, 2G wrote:
On Thursday, September 3, 2020 at 6:19:20 PM UTC-7, AS wrote:
On Thursday, September 3, 2020 at 8:43:52 PM UTC-4, 2G wrote:
On Thursday, September 3, 2020 at 4:40:00 PM UTC-7, wrote:
I've installed three or four of these on Cobra trailers. Very well made and nicely designed. I put them on both single place and two seat glider trailers. They are pretty effective at controlling sway, even though the customers all tow with full-size pickups or SUVs. It definitely helps when towing with a short wheelbase vehicle.

I can't say how effective they are with something like a VW Golf, (but I consider that to be too small to tow a glider anyway. Maybe the wagon, with the longer wheelbase will work better.) I know they tow with tiny vehicles in Europe, but the glider trailers all have an 80 kph limit over there. Here in the US, 75 mph freeway speeds, crosswinds and passing eighteen wheelers are going to make towing a pretty "sporty" adventure. Keep an eye on the rear view mirror. If the trailer changes lanes, try to stay in front of it ;-)

You do have to use an actual 50 mm ball. A two inch ball is too big for the clamping action and 1 7/8" is too small. Remember that it's unlikely that anyone else will be able to tow your trailer unless they also have a 50 mm ball. Order an un-plated (stainless steel) ball if possible. Chrome plating has a tendency to start flaking off under the clamping loads while turning. Lubrication is NOT permitted, as it negates the clamping friction that controls sway. Another issue is making sure the ball CANNOT turn and loosen the nut! No matter how much torque you put on the nut, it can still get loose. In Europe, the ball must be welded to the hitch plate. I usually machined a flat spot on the base of the ball just above the threaded shank and welded a piece of steel bar stock to the hitch plate.

Hope this helps.

80 kph is about 50 mph. Do that on Nevada's 80 mph freeways and they will be scraping you off some 18-wheeler's grill guard.

Tom

Most modern trailers are exempt from the 80 km/h limitation and are allowed to go 100 km/h. Still not the speed some 18-wheelers do here but a big improvement for the German Autobahn.

Uli
'AS'

100 kph is 62 mph - pretty slow by US standards (but not California which has a 55 mph speed limit while towing that nobody obeys).

Tom

I have lived in California for 35 years. I am unaware of this "I can't drive 55" while towing law/suggestion.

Then, Jonathon, your eyesight has deteriorated so badly that you should immediately cease both driving and flying.

Tom

On Friday, September 4, 2020 at 4:55:40 PM UTC-7, wrote:
There are a number of threads on RAS concerning vehicle size vs sway potential. The gist seems to focus on mass and wheelbase of the tow vehicle (more mass, longer wheelbase preferred), fore/aft loading of the trailer (10% of trailer weight on tongue), tire size/construction (radial vs. bias ply) and tire pressure for both the trailer and vehicle (higher pressure = stiffer sidewalls).

Of course, since this is RAS, assorted self proclaimed "engineers" will come out of the woodwork arguing the exact opposite of any of these principles. Using their logic, the "ideal" tow vehicle is a motorized skateboard with silly-putty tires and the ass end of the trailer loaded down. But with vortex generators. Please ignore these people.

Les Sebald would swear that the optimum tow vehicle is a 74 Cadillac Coupe DeVille due to it's massive length and weight. Bonus was the luxury driver/passenger comforts plus style points.

On Friday, September 4, 2020 at 4:55:40 PM UTC-7, wrote:
There are a number of threads on RAS concerning vehicle size vs sway potential. The gist seems to focus on mass and wheelbase of the tow vehicle (more mass, longer wheelbase preferred), fore/aft loading of the trailer (10% of trailer weight on tongue), tire size/construction (radial vs. bias ply) and tire pressure for both the trailer and vehicle (higher pressure = stiffer sidewalls).

Of course, since this is RAS, assorted self proclaimed "engineers" will come out of the woodwork arguing the exact opposite of any of these principles. Using their logic, the "ideal" tow vehicle is a motorized skateboard with silly-putty tires and the ass end of the trailer loaded down. But with vortex generators. Please ignore these people.

Sometimes pictures are better than words as it is harder to argue with what you can see with your own eyes (assuming that you can still see, unlike Jonathan):
https://www.youtube.com/watch?v=-uvPIjaK01A
https://www.youtube.com/watch?v=iCDt4tjxp-E
https://www.youtube.com/watch?v=YjZn_zQt_Q0
https://www.youtube.com/watch?v=UdmlPu33Iew
The cause of many of these accidents is pretty obvious: tow vehicle too small, very bad trailer load distribution, and speed. Others are not obvious from the video. One thing that is common: the time period between initial instability and the crash is very short, a few seconds.

Tom

I am all about two heavy duty crossed chains as a last line of defense. Had a glider trailer come off the ball in a patch of rough downtown Omaha construction zone (cause - underjaw not tight enough). The chains saved the day causing nothing more than a broken 4-flat cable.

I have heard that in Europe that chains are not required (not allowed?). True? Something about saving the driver by getting rid of the trailer instead of tipping over the vehicle. While I get that concept I would much rather risk my own life than injure, or kill, an innocent person hit by my trailer.


My $0.02.

John DeRosa OHM Ω http://aviation.derosaweb.net wrote on 9/5/2020 1:33 PM:
I am all about two heavy duty crossed chains as a last line of defense. Had a glider trailer come off the ball in a patch of rough downtown Omaha construction zone (cause - underjaw not tight enough). The chains saved the day causing nothing more than a broken 4-flat cable.

I have heard that in Europe that chains are not required (not allowed?). True? Something about saving the driver by getting rid of the trailer instead of tipping over the vehicle. While I get that concept I would much rather risk my own life than injure, or kill, an innocent person hit by my trailer.

The trailers have a "break-away" cable that activates the handbrake on a Cobra
trailers, so the trailer will slow and stop. It might be better to have a loose
trailer that is braking hard, than an out of control-car-sliding around with a
trailer attached. The crossed chains you and I use is the usual recommendation,
but I doubt it would keep the trailer stable at highway speeds, even behind a
heavy, stable vehicle; instead, it is likely to begin whipping widely until you
slowed down, the chains broke, or it hit something.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Saturday, September 5, 2020 at 3:54:38 PM UTC-5, Eric Greenwell wrote:
John DeRosa OHM Ω http://aviation.derosaweb.net wrote on 9/5/2020 1:33 PM:
I am all about two heavy duty crossed chains as a last line of defense. Had a glider trailer come off the ball in a patch of rough downtown Omaha construction zone (cause - underjaw not tight enough). The chains saved the day causing nothing more than a broken 4-flat cable.

I have heard that in Europe that chains are not required (not allowed?).. True? Something about saving the driver by getting rid of the trailer instead of tipping over the vehicle. While I get that concept I would much rather risk my own life than injure, or kill, an innocent person hit by my trailer.

The trailers have a "break-away" cable that activates the handbrake on a Cobra
trailers, so the trailer will slow and stop. It might be better to have a loose
trailer that is braking hard, than an out of control-car-sliding around with a
trailer attached. The crossed chains you and I use is the usual recommendation,
but I doubt it would keep the trailer stable at highway speeds, even behind a
heavy, stable vehicle; instead, it is likely to begin whipping widely until you
slowed down, the chains broke, or it hit something.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Eric - While most modern glider trailers have a brake activation cable (Cobra in particular) my event was years ago while pulling a home built trailer which, unfortunately, did not have any brakes at all. I was probably going 60mph-ish (100kph-ish) when the trailer did a pretty wild dance shaking up my 2003 Nissan Pathfinder. I thought it was a flat tire. I let off on the gas (no braking initially) and coasted to a safe stop.

Maybe this is obvious but bears repeating - the point of the crossed chains is keeping the coupler off the ground. My newer Cobra trailer has a V shaped "stand" welded to the tongue's underside to also help keep the coupler off the ground. These features attempt to prevent the coupler from dragging on the pavement to avoid hitting a gap in the road's surface which can cause the trailer to come to a very abrupt stop, probably immediately severing the trailer/vehicle connection. Not good.

Still, am I right that trailer chains are not used in Europe?