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12-13-2010, 06:08 AM
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#81
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Rivet Master
1976 25' Tradewind
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, Maine to Arizona
Join Date: Sep 2004
Posts: 621
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Time For a New Hitch for me
Great timing Andy, I need a new hitch.
Looking forward to seeing your results.
In response to some posts, with all that math, tapered bars and anti sway de-vices, it is easy to forget that; the load needs to be balanced in the trailer and tow vehicle, tires inflated to proper level and most importantly the driver should have some experience, common sense and be wearing the thinking cap.
__________________
"Talk is cheap, Airstreams are expensive," Wally Byam.
25' Tradewind
'18 Promaster 1500 High Roof
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12-13-2010, 06:48 AM
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#82
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by fastrob
Great timing Andy, I need a new hitch.
Looking forward to seeing your results.
In response to some posts, with all that math, tapered bars and anti sway de-vices, it is easy to forget that; the load needs to be balanced in the trailer and tow vehicle, tires inflated to proper level and most importantly the driver should have some experience, common sense and be wearing the thinking cap.
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Very true, and I am assuming a proper static setup, per scales and vehicle load specs for all conversations. That should be anyone's startin g point before discussing bar load increases during travel, etc.
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12-13-2010, 06:58 AM
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#83
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by barts
If we assume bars have length L and spring constant k, and we
denote the truck beginning to climb a hill as a positive angle theta, we
can say (assuming small angles of deflection, blah blah):
force due to hill = L * sin(theta) * k
or for a 24" bar, 10% grade (5.7 degree slope) and 500 lb/inch spring constant:
24 * sin(5.7) * 500 = 1190 lbs....
So climbing a steep hill effectively bends the bars a bit more than 2" extra....
Those w/ 1000 lb bars can wince now...
This is why I feel a more constant force hitch would be a good thing for
one's trailer if one needs a WD hitch... and why those headed off road may wish to relax their WD bars somewhat...
- Bart
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Yup, I get that. What I wold like to see eventually, is a spreadsheet with various slopes and loads. I would like to get to the place where I can eyeball a steep entry and say "that rise is about 24" over the length of my TV wheelbase, so I am weel within the load limits of my AS frame, hitch, etc." Or, conversely, "I gotta get out and unload the bars..."
Does anyone have any idea on the physical property specs of AS farmes for the various build configurations?
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12-13-2010, 07:06 AM
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#84
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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Quote:
Originally Posted by fastrob
Great timing Andy, I need a new hitch.
Looking forward to seeing your results.
In response to some posts, with all that math, tapered bars and anti sway de-vices, it is easy to forget that; the load needs to be balanced in the trailer and tow vehicle, tires inflated to proper level and most importantly the driver should have some experience, common sense and be wearing the thinking cap.
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All of that if fine and dandy, and I will not disagree with any of it, but keep in mind Andy is only testing bars amount of bend vs load in these tests:
"We are measuring the bend in the load equalizing bars, at 100 pound increments, with different brands as well as square and round bars.
The range of the tests start at a low level and up to and including a 20 to 25 percent overload."
Personally, I think he needs to measure the amount of weight needed to bend each bar 1", and in additional 1" increments, rather than measure the bend at each 100 pound of weight loading. I think he will end up with so much data the way he says he is going to test that it will simply be confusing.
As an example, if testing a 1000 pound bar, he will have no less than 12 measurements for each bar if he goes to 20% overload.
__________________
Regards,
Steve
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12-13-2010, 07:12 AM
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#85
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by SteveH
All of that if fine and dandy, and I will not disagree with any of it, but keep in mind Andy is only testing bars amount of bend vs load in these tests:
"We are measuring the bend in the load equalizing bars, at 100 pound increments, with different brands as well as square and round bars.
The range of the tests start at a low level and up to and including a 20 to 25 percent overload."
Personally, I think he needs to measure the amount of weight needed to bend each bar 1", and in additional 1" increments, rather than measure the bend at each 100 pound of weight loading. I think he will end up with so much data the way he says he is going to test that it will simply be confusing.
As an example, if testing a 1000 pound bar, he will have no less than 12 measurements for each bar if he goes to 20% overload.
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We can do the math either way. I like more data points. More data is good IMO.
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12-13-2010, 08:44 AM
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#86
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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I'm not saying a lot of data is bad, just that it can be confusing. Many times in lab type tests, there is so much data that no one but an engineer can actually make a determination from it. It leads to arguments many times.
We all here know that arguments are possible.
__________________
Regards,
Steve
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12-13-2010, 10:25 AM
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#87
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by SteveH
All of that if fine and dandy, and I will not disagree with any of it, but keep in mind Andy is only testing bars amount of bend vs load in these tests:
"We are measuring the bend in the load equalizing bars, at 100 pound increments, with different brands as well as square and round bars.
The range of the tests start at a low level and up to and including a 20 to 25 percent overload."
Personally, I think he needs to measure the amount of weight needed to bend each bar 1", and in additional 1" increments, rather than measure the bend at each 100 pound of weight loading. I think he will end up with so much data the way he says he is going to test that it will simply be confusing.
As an example, if testing a 1000 pound bar, he will have no less than 12 measurements for each bar if he goes to 20% overload.
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I see what you mean, but from his brief description, you could interpret his methodology either way. He may be doing what you suggest in your statement.
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12-13-2010, 10:35 AM
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#88
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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Quote:
Originally Posted by barts
If we assume bars have length L and spring constant k, and we
denote the truck beginning to climb a hill as a positive angle theta, we
can say (assuming small angles of deflection, blah blah):
force due to hill = L * sin(theta) * k
or for a 24" bar, 10% grade (5.7 degree slope) and 500 lb/inch spring constant:
24 * sin(5.7) * 500 = 1190 lbs....
So climbing a steep hill effectively bends the bars a bit more than 2" extra....
Those w/ 1000 lb bars can wince now...
This is why I feel a more constant force hitch would be a good thing for
one's trailer if one needs a WD hitch... and why those headed off road may wish to relax their WD bars somewhat...
- Bart
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Hmmm, Bart, how would you do that? Some sort of spring on a saddled spring setup? Better get your patent application in now!
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12-13-2010, 06:05 PM
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#89
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Maniacal Engineer
1971 25' Tradewind
Lopez Island
, Washington
Join Date: Jan 2010
Posts: 1,244
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Quote:
Originally Posted by dznf0g
Hmmm, Bart, how would you do that? Some sort of spring on a saddled spring setup? Better get your patent application in now!
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I'm inclined to suggest a suspension air bag w/ an external reservoir to increase volume as a useful relatively constant force spring. You adjust the pressure to control the amount of weight transfer; three-way solenoid valves could be used to release the air pressure on each bag to permit unhitching w/o emptying the reservoir. Any flow restriction between bag and reservoir would act as a damper to decrease pitching.
- Bart
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12-13-2010, 06:09 PM
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#90
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Rivet Master
2007 30' Classic
Oswego
, Illinois
Join Date: Jul 2010
Posts: 13,655
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There ya go! Git 'er done, and send me a free sample to test out.
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12-30-2010, 11:10 AM
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#91
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3 Rivet Member
1986 25' Sovereign
Plant City
, Florida
Join Date: Mar 2010
Posts: 228
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Andy,
Any update on this?
Chris
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12-30-2010, 02:54 PM
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#92
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by ck21084
Andy,
Any update on this?
Chris
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The research has been completed.
The write up however, is taking some time, as I want it to be as simple as I can, so as to minimize negativity.
A few more days should do it, since I have been very busy with some other projects as well.
Andy
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12-31-2010, 08:52 AM
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#93
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by SteveH
All of that if fine and dandy, and I will not disagree with any of it, but keep in mind Andy is only testing bars amount of bend vs load in these tests:
"We are measuring the bend in the load equalizing bars, at 100 pound increments, with different brands as well as square and round bars.
The range of the tests start at a low level and up to and including a 20 to 25 percent overload."
Personally, I think he needs to measure the amount of weight needed to bend each bar 1", and in additional 1" increments, rather than measure the bend at each 100 pound of weight loading. I think he will end up with so much data the way he says he is going to test that it will simply be confusing.
As an example, if testing a 1000 pound bar, he will have no less than 12 measurements for each bar if he goes to 20% overload.
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How I designed the tests, was my choice.
They were designed to help the "majority", and not the "minority" that have already expressed negativity, even before the results are published.
Since you already disagree with that, then I would suggest you invest your own money, and time, and test them to your satisfaction.
Then, others can disagree with your test results.
Because of the negativity, from a small source, we will publish the results on our web site, only, with a copyright.
Andy
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12-31-2010, 10:01 AM
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#94
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Rivet Master
1976 25' Tradewind
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, Maine to Arizona
Join Date: Sep 2004
Posts: 621
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Dear Andy,
I appreciate your efforts over so many years.
Not saying you are old, but I retired yesterday and I have followed your work for quite a while now.
In the next two weeks or so I am buying a load leveling hitch for my Airstream and a utility trailer. IS any of the information you derived useful as a sort of buying guide or is it engineer speak for top capacity Airstreams?
I was thinking of something simple, like me.
Thanks for all the parts and info.,
Rob
__________________
"Talk is cheap, Airstreams are expensive," Wally Byam.
25' Tradewind
'18 Promaster 1500 High Roof
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12-31-2010, 10:49 AM
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#95
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by fastrob
I appreciate your efforts over so many years.
Not saying you are old, but I retired yesterday and I have followed your work for quite a while now.
In the next two weeks or so I am buying a load leveling hitch for my Airstream and a utility trailer. IS any of the information you derived useful as a sort of buying guide or is it engineer speak for top capacity Airstreams?
I was thinking of something simple, like me.
Thanks for all the parts and info.,
Rob
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Rob.
I assume you still have the "Jeep".
If so, it's an OK tow vehicle for maybe a 17 to 18 foot Airstream, because of it's short wheel base.
To me, towing a 24 footer, is way past the "safe" point.
But, since you asked, probably a 750 to 800 pound full sway control hitch would be OK.
But, make super sure you have a full sway control, since in your case, the tail will easily wag the dog. Meaning, that your Airstream will shove your Jeep around as it pleases.
If your Jeep has a rigid suspension, then drop the rating down 200 pounds, as your rig will need all the help it can get.
Above all, be safe.
Andy
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12-31-2010, 12:57 PM
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#96
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Rivet Master
1981 27' Excella II
mays landing
, South Jersey
Join Date: Nov 2009
Posts: 1,179
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I agree with Andy. first started towing 27 ft. Excella with a 1987 Dodge shot bed PU. Not too much longer than a Jeep. Very stiff susp. Just did not feel safe. Upgraded to a F250 extended cab long bed. All the difference in the world. Sal.
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12-31-2010, 09:25 PM
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#97
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by fastrob
I appreciate your efforts over so many years.
Not saying you are old, but I retired yesterday and I have followed your work for quite a while now.
I was thinking of something simple, like me.
Thanks for all the parts and info.,
Rob
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Rob.
"OLD" is a state of mind.
Thinking and working, like a young person, "as long as the meds hold out" is the way to go.
If I quit, what would I do?
Gotta stay busy doing something productive.
Some say I lie about my age, and I say, "no I don't", but I do lie about my looks.
Keeping at least somewhat busy, is what makes the wheels keep turning.
Andy
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01-01-2011, 01:11 AM
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#98
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Be Calm, Have a Cupcake
Vintage Kin Owner
Houston
, Texas
Join Date: Nov 2007
Posts: 223
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The Majority Values Your Work
Andy,
Forget about the naysayers. From what I can see in the forums, the vast majority of members value all your posts and comments. When someone of your vast experience and expertise goes to the trouble to conduct testing that has not been conducted by the industry or manufacturers, and that entirely at their own expense, not subsidized by any manufacturer, I for one am interested in the results.
It certainly makes no sense to criticize before the results are published. The fact that the results are NOT subsidized by any manufacturer speaks volumes about your integrity.
I hope you will reconsider and publish the results here in the forum.
__________________
Secguru
Would you rather have a mansion full of money or a trailer full of love?
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01-01-2011, 09:44 AM
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#99
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Incorrigible
1976 Argosy 24
--
, Georgia
Join Date: Jun 2007
Posts: 559
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Quote:
Originally Posted by Inland RV Center, In
The research has been completed.
The write up however, is taking some time, as I want it to be as simple as I can, so as to minimize negativity.
A few more days should do it, since I have been very busy with some other projects as well.
Andy
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Will you be loading it under the "Projects" or "Articles" link on the Inland RV site?
Thanks.
__________________
Tim
1976 24' Argosy
1973 International Harvester Travelette 1210 4x4 'Bernard' 164" WB
1997 Georgie Boy 30' SuperDuty v10
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01-01-2011, 11:18 AM
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#100
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Rivet Master
Airstream Dealer
Corona
, California
Join Date: Feb 2002
Posts: 16,497
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Quote:
Originally Posted by Ike T
Will you be loading it under the "Projects" or "Articles" link on the Inland RV site?
Thanks.
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Articles.
Andy
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