How Do Airstreams Perform on The Road

[Moflash]

Originally Posted by Adventure.AS

Another factor which is often overlooked is the rear overhang. The shorter the distance from the ball to the rear axle adds to stability of the TV. For most pickup trucks this overhang (52.4") is far greater than a good SUV (41.8") or passenger vehicle.

Your statement is correct for 5th wheel trailers which have much heavier tongue weights along with Semi tractor trailers.

Actually a short wheelbase tow vehicle at or near it’s factory recommended tongue weight coupled with a short overhang is a recipe for disaster as a tailwagging trailer takes over.In most cases there is no recovering especially with lighter weight tow vehicle.
This downfall also becomes apparent on a steep decline with a long curve and a trailer much heavier than the tow vehicle.

[streaminwild]

Originally Posted by slowmover

Not that it can’t be taught or sufficient skill acquired. Some start with better visuospatial skills (monkey skills), but none are exempt from learning procedures.

I have ''monkey skills''. At the zoo, a monkey taught me to peal a banana from the bottom up...much easier. Common sense is not so common anymore. When towing you stay under 65mph. With a heavy wind, you go slower. Snow.......................don't even think about it. Don't tell me you been pealing bananas wrong all this time

[Adventure.AS]

Originally Posted by Moflash

...
Actually a short wheelbase tow vehicle at or near it’s factory recommended tongue weight coupled with a short overhang is a recipe for disaster as a tailwagging trailer takes over. ...

This is the physics of moment but perhaps I am missing something. Could you please explain how you arrived at your conclusion. The following is my understanding of the force at work on the hitch.

Moment can easily be understood if one recalls using a wrench. We have all experienced that more force is required with a short wrench (6" moment) than a long wrench (18" moment) when trying to loosen a nut or when tightening a nut using a torque wrench. (Thank heavens for 'cheater bars' )

The short rear overhang of a SUV is an illustration of a shorter moment arm. Any force on the hitch of the SUV, made by the trailer coupler, will have less force applied to the rear axle of the tow vehicle (short moment arm) than the same force applied to the longer moment arm overhang of a pickup truck.

Given a similar rear axle loading and a SUV with a short rear overhang, more sideways force at the coupler is required to break the rear tires loose. This alone makes the rig more stable. Combine that with proper trailer loading, weight distribution, sway control devices and above all lower speed and the rig will be able to withstand higher initial 'tail-wagging' forces allowing an attentive, experienced and skilled driver to maintain control.

IMO a massive tow vehicle may only serve to mask the incipient "tail-wagging" providing an illusion of control of an improperly tuned rig.

[BillF95]

This is the way I understand physics. How can a short overhang NOT decrease moment (and be better than a longer one)?

[Moflash]

The closer the rear axel is to the hitch the more lateral movement the vehicle will have when tail wagging occurs.Resulting in almost immediate lose of control for a novice driver.
Still don’t understand? place your cell phone on a flat surface place your thumb and your middle finger on each side 1/2 inch from the end.Now simulate tail wagging by moving just the rear back and fort a1 inch or so..Now place your fingers 2 inches from the back and move it the same distance back and forth.The farther back you place your dings the more the lateral movement when this situation arises.
Simple physics ??
By the way In my country a pickup truck is not considered a “massive vehicle “ Lol

[PKI]

Originally Posted by Moflash

-- snip -- place your cell phone on a flat surface place your thumb and your middle finger on each side 1/2 inch from the end.
-- snip -- Simple physics ?? -- snip --

Your example ignores your wheelbase argument and does not include the resistance of the front tires. You need four fingers. Also, note the recommended action for sway is to accelerate the tow vehicle and apply the trailer brakes. Neither is negatively impacted by short wheelbase or overhang. Pat

[Adventure.AS]

Originally Posted by Moflash

The closer the rear axel is to the hitch the more lateral movement the vehicle will have when tail wagging occurs.Resulting in almost immediate lose of control for a novice driver.
...

The amplitude of rear tire movement is irrelevant in this discussion. If the TV tires break contact, at all, you've got a problem that only the most skillful driver may be able to resolve. Once your rear tires break loose you have lost control and it's all over except the crying. A "tail-wagging" loss of control event is related to the breaking of the contact patch of the tires with the pavement, not how much they move laterally with the first application of sideways force at the coupler.

If you watch trailer accident videos on line you will see that the trailer starts moving before the rear of the tow vehicle breaks loose. There is a short opportunity to regain control, with proper technique such as acceleration of the TV while manually applying the TT brakes.

If my previous post with the illustration of the torque on a wrench didn't work for you, think about the principle of a lever.

To reiterate, moment arm is the key factor in resistance to the lateral force which is being applied at the coupler by the trailer movement. With a pick up truck's longer rear overhang it will take less force (i.e. less movement of the trailer) for loss of adhesion to occur at the TV rear axle. This is because the lateral force is being multiplied by the moment arm. Even through the same amount of force is being applied at the ball as with the pick up, a short overhang SUV will experience less lateral force at the rear axle.

To me this the obvious advantage for an attentive driver of a SUV can apply corrective measures before the TV tires break contact.

I am not suggesting that a pick up truck isn't the right vehicle for some, like those who need to carry a lot of stuff. A SUV isn't for everyone, but if stability and the safety of your rig is important to you , a short overhang vehicle, like a SUV, should be considered before a long overhang TV.

[Moflash]

Actually you are incorrect on your statements.

[Moflash]

Originally Posted by PKI

Your example ignores your wheelbase argument and does not include the resistance of the front tires. You need four fingers. Also, note the recommended action for sway is to accelerate the tow vehicle and apply the trailer brakes. Neither is negatively impacted by short wheelbase or overhang. Pat

My wheelbase statement is not a argument but is a known fact.

If you do some research you will find I am correct......

https://caravanchronicles.com/unders...f-towing-pt-2/

[PKI]

Originally Posted by Moflash

-- snip --
https://caravanchronicles.com/unders...f-towing-pt-2/

Read the linked blog. It says that a longer distance from axle to ball increases the applied force. They also explain how wheelbase mitigates that force, but it does not reverse the physics as you are arguing with your cell phone example.

Also, Slow's data has not gone stale. No one pulls their coach with a AA Fuel dragster, because we all go around corners. There is a point of diminishing returns on the wheelbase "argument".

And more to the point. This is a thread on towing safety. It is a not a discussion where laughter has much traction. Pat

[Moflash]

I did not realize that I had entered into a Can Am propaganda forum.

You need to read it again.....lol

[BillF95]

Doesn’t seem that way to me. The article you linked says:
“What else have we learned?

Well we have proved that a longer wheelbase is preferable to a shorter wheelbase given the same towing conditions and trailer, and we have also proved with a bit of school maths that a short tow bar to rear axle length is better than a long tow bar as it imparts less sideways (lateral) force on the rear axle and tyres.”

Short overhang “towbar” is a good thing..l

[PKI]

From your link

"In general, a longer wheelbase (axle to axle distance) and shorter tow bar length (rear axle to tow ball distance) will make for a more stable tow vehicle."

I can read that again, but it does not change the physics to the position you stated. A longer tow bar length does not improve stability. Within reason, a longer wheelbase helps. Was that your point? Pat

[jcl]

Originally Posted by Moflash

My wheelbase statement is not a argument but is a known fact.

If you do some research you will find I am correct......

https://caravanchronicles.com/unders...f-towing-pt-2/

Moflash, do you have training in physics? The problem appears to be your focus on lateral movement, and not on lateral forces. Suggest you start with the forces. They are what produce the motion, not the other way around.

Let's take the example of a trailer tongue quickly moving laterally, and consider that the starting point. If you assume that the front tires are fixed in place laterally, and that the lateral tongue movement translates to an instantenous movement of the rear tires, then I see your point about a longer moment arm being better, because it reduces the lateral movement of the rear tires. The problem with this form of analysis is that you have to assume things that aren't in fact correct to even get here.

First, the front tires are not fixed. The vehicle is not yawing left or right around a front axle pivot.

Secondly, we can't get to a significant lateral movement of the tongue without going through the steps that happen first. The forces that are applied.

First, the trailer pushes to the side. Could be wind, a bow wave from a passing truck, or what have you. That lateral force (not motion) is transmitted through the hitch ball. With a longer moment, there is more yawing force on the tow vehicle. That is why a shorter overhang is better. That is why a 5th wheel has the shortest distance, essentially zero. The resistance to this lateral force is the contact patch of the rear tires. They are planted, for now, in this example. The lateral force causes the tow vehicle to yaw (turn left/right) opposite to the force at the hitch. Use your cell phone. Pin it in the centre of the screen, that represents the rear tire contact patch. Push on the bottom of the phone, and the top shifts to the other side. Yaw. Now the driver notes that the vehicle has been impacted, and so corrects, turning the other way, correcting the yaw. That pushes the tongue back opposite to the direction it moved first, because of the moment from the rear axle to the hitch. Now we have set up a sway situation, with an oscillation. A shorter moment (rear axle to hitch point) is always better.

Your link explains all this. You just need to focus on the forces, and not assume that the initiating action is a sudden displacement of the hitch laterally, without any lead in. Because by the time your hitch jumps a significant distance to the side, it is too late.

[DBinSD]

All interesting...

I just read a study that said the closer to your combined gross vehicle weight rating CGVWR the higher susceptibility the tow vehicle is to oscillation (sway). Especially at higher speeds.
They said this alone had the single greatest effect.

[slowmover]

Originally Posted by Moflash

Sorry Slowmover but your 70 year old test results are laughable at best.

You counter it with what? Your pickup is better than a current Charger (the RWD fleet police choice)?

Specify “how” your pickup is better. Start with the empty FF/RR weight bias. And post your scaled bed load numbers (those items which cannot be stored in the trailer or RV passenger compartment).

I guess ol’ Isaac Newton and questions on gravity are out of date by a few centuries.

I won’t hold my breath. You’ve yet to exhibit other than manufacturer advertising copy responses.

.

[slowmover]

Originally Posted by Moflash

I did not realize that I had entered into a Can Am propaganda forum.

You need to read it again.....lol

It’s because you literally refuse to understand basics. Or how tens of thousands of others had better rigs than yours. A half century ago.

[Moflash]

Originally Posted by slowmover

It’s because you literally refuse to understand basics. Or how tens of thousands of others had better rigs than yours. A half century ago.

Lol, u guys are hilarious.

[PKI]

Originally Posted by Moflash

Lol, u guys are hilarious.

You continue to laugh at a very serious issue. You provide incorrect analysis. You insult experienced contributors. No, not the least bit Hilarious. Solution = IGNORE status.

[Moflash]

Slow mover your test results 50- 60 years old . Your above statement is you belief that vehicles were better tow vehicles in that time frame.
I did I mention my tow vehicle.I have been watching your repetitive statements regurgitating Can Am’s propaganda.Not everyone drinks the Koolaide.All vehicles are purpose built and have their limits.You can make modifications to allow them to do things that they were not designed to do.I get that.But that does not make them a superior tow vehicle.
Shorter wheelbase vehicles with less overhang, lighter in weight with independent suspension a 50/50 weight distribution and large brakes make a good track vehicle but are severely lacking when towing a 25ft+ trailer With 800-1200lbs tongue weight.

I have 40+ years in the automobile business.I am certified in medium,duty and HD trucks.I have in my career ordered literally thousands of them.I have studied suspension design and theory.I am a member of Chevrolet’s legion of leaders and Chevrolet trucks Hall of Honor.Not to mention product knowledge champion for Chevrolet Motor division.I have done consulting for Mercedes Benz,Porsche,Ferrari,Lamborghini and Ford.
I have been to the factories met the designers engineers and workers.
I have driven the fastest cars in the world on most of the major race tracks in the USA and Europe.I am also a certified technician.

I am still learning and keep a open mind but I see all these bs posts so at times like this I call BS.

It’s amazing how many people on here preach and beat their chest on automotive design,engineering and physics and have zero experience or knowledge in a automotive background.

Slowmover I bet you are a great truck driver and I respect your experience.But your chip on your shoulder for light duty trucks is not justified.Vehicles are designed and engineered for a specific purpose.

I do not think everyone needs a pickup truck.But some of the poor choices for tow vehicles that I see on this forum being justified is just sad.I don’t know everything but I have learned a few things along the way.

Peace out