Air suspension for a 12 Trailer

One of the things I've seen with trailers (boats and caravans) is it bouncing all over the road while the vehicle pulling it, is gliding along. After some investigation with trailer manufacturers, who deem 1400lb "light weight"; leaf springs are worse for this bounce than the rubber "springs" used for little squre box trailers. Both are pretty bouncy. Air suspension is king for a smooth ride.

The advantage of air suspension is that it can be lowered or raised, and gives an exceptionally smooth ride, typically used in the luxury end cars range rovers, mercs, rollers etc. Air suspension kits are sold typically to modify cars, low riders for example, that can be pumped up to legal heights if required.

If you could lower the suspension of the trailer, then the angle of the aircraft loading could be reduced, reducing chances of tail strikes, less force to pull/push it onto the trailer and most importantly a smoother ride giving the instruments/component/nuts and bolts inside the RV less stress, rattle and roll.

My plan is to keep the 12 at home, so I need to know it is going to work in real life.

There are some interesting threads on design shapes and sizes however has anyone considered air suspension?

Trailers

Grant Stewart said:

One of the things I've seen with trailers (boats and caravans) is it bouncing all over the road while the vehicle pulling it, is gliding along. After some investigation with trailer manufacturers, who deem 1400lb "light weight"; leaf springs are worse for this bounce than the rubber "springs" used for little squre box trailers. Both are pretty bouncy. Air suspension is king for a smooth ride.

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My instructor at the LSA Repairman course commented that over the years he has seen a lot of damage to planes done from riding on trailers. All those bumps and potholes working on the stiff trailer suspension is not good with that airplane engine hanging on its mounts. I am planning to hangar but will be taking it easy trailering the plane to the airport.
Tony

Tony_T said:

My instructor at the LSA Repairman course commented that over the years he has seen a lot of damage to planes done from riding on trailers. All those bumps and potholes working on the stiff trailer suspension is not good with that airplane engine hanging on its mounts. I am planning to hangar but will be taking it easy trailering the plane to the airport.
Tony

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I think this is because the trailer needs to be designed and built for the application. This is rarely done. Adapting a closed trailer that is designed to haul a car and putting an RV-12 in it is a guaranteed way to beat it to death.

The suspension needs to be designed for the total weight of the trailer and what will be hauled in it.

I think the air suspension has a lot of merit.

Regardless of the type of spring, a good set of shock absorbers is a must for a smooth ride.

Suspension

Many years ago I built a 15 foot sailboat and I had the same concern about the boat being too light for the trailer. I designed a trailer with independent suspension instead of the beam axle with leaf springs. My suspension consisted of 2 trailing arms and a shock absorber integrated with a helper spring on each arm. It worked terrific. Recently a friend came over to show me his new kayak and behold the trailer was similar to the one I built 35 years ago! Search kayak trailers for ideas such as this one: http://www.cabelas.com/cabelas/en/c...ayak and Canoe Trailer&tProdID=0019960018515a

Ken

Scott,

What kind of rig did Mr. Partain use when he hauled the RV12s to Florida?

I believe this is the heart of the problem. The vast majority of trailers of any sort, have no dampeners at all. Leaf springs are the worse, torsion axles have some dampening in them due to their design. To ride like a smooth car, you need to have shock absorbers of some sort. Monroe makes an aftermarket kit to add shocks to most typical leaf spring trailers.

Mike S said:

Regardless of the type of spring, a good set of shock absorbers is a must for a smooth ride.

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Go with torsion axles, I have them on my 7x14 enclosed trailer ... rides very smooth. I agree with everyone, you need a trailer designed to carry the weight. Many trailers have spring rates much higher than the axels or tires could carry maing for a rough ride.

http://www.dexteraxle.com/torflex_axles


two more points;

1. many people don't balance their trailer tires ... all tires should be balanced.
2. lots of 'cheapy' trailer tire/wheel combos are out of round (you can see it when you try and balance the tire), check the rims before buying.

I've found replacing a out of round rim and balancing all my trailer tires years ago, the trailer tows much better.

They make a trailer like that about 50 miles away from me. Most of them are open trailers, but he has been making them for at least 10 years. They work great, but cost a little more than a spring model. He also make an air ride hitch, called the shocker. I have one and it works great.

Google Bob Sagen in Arthur, North Dakota. He came up with them. I don't think he has a web site. They were called travel-lite trailers.

Vistos trailer sales also sold them, you could try them.

http://vistotrailers.com/Index.htm

RV-12 Trailer

Not much (if any) recent talk about trailering an RV-12. Guess that the people at Van's were right when they said that most of us would just use a hanger. There are no affordable hangers in So Cal that I know of. Trailer is a must as I see it. It'll be interesting to see if I can find a local airport that will allow me access while using a trailer. Wonder if the security zars have decided that people with airplanes on a trailer are a security risk??? How absurd.

I'll still want to trailer my 12 home but we'll see how practical that is when the time comes. Another reason to move from So Cal permanently.

While I am in favor of a top quality trailer for the RV-12 for the people who need to keep them off airport or folks that just want to tow it behind their motor-home I think many of us are overlooking an additional value in the quickly removable wings.

At many airports hangar space for an aircraft is very hard to find and/or very expensive, we have this at my field where the hangar fee for a RV of any type is about $ 350 per month and this is cheap as the hangars cost about $ 300,000 to own. With the RV-12 we can make do very nicely with only a 20 x 10 foot corner of the hangar and we can create a new source of revenue in a hangar that will not accommodate an additional full aircraft. We have seen people here offering this space for only $ 100 per month which is still a lot but it is a great deal less than $ 350. Many of you will be able to find similar arrangements (many for less money) from people who have a smaller aircraft and a larger T-hangar because it was all that they could get. In some areas square or rectangular hangars are the norm and they always have this kind of extra space, that is if the owner has not filled it with other junk.

It is probably better for a RV-12 if it is not trailered to and from each flight even a good trailer will extract some wear each trip and just having to remove the wings and placing them in a good wing rack is a very simple task compared to hooking up your trailer, driving to the airport, getting the trailer on the ramp, unloading the RV-12 from the trailer then installing the wings, then close up the trailer and perhaps having to move it to some parking area and then you can go fly with the prospect of doing the reverse after the flight. I did it for years with gliders and you get good at it, so it is very do able it is just simpler to remove the wings and push it into the hangar.

Have a good day.

Best regards,
Vern

If it is of any help I have a trailer designed specifically for motorcycles - its a box trailer, mfg'd by Highpoint (no longer in business I'm afraid). It rides very smooth; I've ridden in the back while a friend towed it around a dirt/gravel parking lot and road. The ride is smoother than the 3/4 ton surburban that was doing the towing.

It uses rubber elastomer torsion axles. No shock absorbers, but the rubber seems naturally damped.

I've in the past had an open trailer that was home made using the rear axle, wheels, suspension and shock absorbers off a front wheel drive vehicle (I suspect a minivan, but am not entirely sure). That also had a very smooth ride.

I found a number on the hitch I mentioned earlier for travel lite trailers, it is listed as 1-877-nine six seven-eight five seven seven

Air suspension is great, however, it creates a lot of complexity. Onboard compressor or connection to towing vehicle with onboard compressor, air tank, leveling valve, dump valve, plumbing, etc.., and that's just for the air system.

I own a trailer manufacturing company.
TRUE air ride starts generally with 6,000# to 8,000# axles. You can get air ride assist for 3500 axles but its in conjunction with spring axles. all light duty trailers bounce. we cannot build an enclosed trailer because the rv 12 landing gear is too wide to fit in our largest door opening! airplane is too wide.

These guys make a trailer that fit my Highlander that needed a door wide enough for it, which was 6 foot & 10 inches.

Classic Trailers of Sturgis, MI

http://www.classicmfg.com/

AV2682TE is the model #

Call Randy at (800) 826-1960 or (269) 535-0002 for a quotation or to leave a message. You can also email Randy at [email protected].

Thanks!

Thank you for the valuable updates to this thread. I've more info coming in from air suspension suppliers in the US, the UK seems to draw a blank.
Shocks are required but it seems that it is an affordable and practical option if you decide to have "fixed" air pressure rather than inflatables which require pumps and valves. I'll update it with facts and figures when I have them.

I'm working on a sketchup cad drawing, and I've everything else exept an RV12 in 3D, so in true fashion I'm now distracted and working on a 3D RV12. 80% there.

This may be counter to most thoughts but adding 1000 lbs in the form of dead weight (we used a 1/2" metal plate welded to the frame) and a set of good shocks made all the difference in our trailer (102" wide by 27' long) for hauling kits and fast builds from ohio to washington.

Door Width

At the risk of hijacking the thread, I would like to share my thoughts. The door width should not be a problem if you have a tailgate that buts up against the rear of the trailer. The bigger problem I see is the width of the side walls. Let me explain. The maximum overall allowable width of the trailer Downunder is 2.5M. ( 98.4"). If the width of the stab is 8' (96"), the wall thickness for both sides cannot exceed 2.4" for the area of the stabiliser. The other problem is the Gear width. The distance between the wheel arches must be wider than the gear width. (plus any additional wheel fairings in the future.) I cant find the gear width spec that Van posted for us, but it was around 7'. That leaves about 6" for each wheel arch. (that will mean the wheel width cannot exceed 4"). The solution could be to have a flat floor. The downside is that the floor height will be higher, leaving a steeper ramp angle, and higher overall trailer. Inside height of the trailer will need to be 8' minimum, (if you dont run the nosewhheel up onto a ramp. to dip the tail lower.) Overall this will be a BIG trailer.

If not trailering very far, and not overnight, wouldn't an open trailer with a stone shield on the front be both adequate and cost effective.

In a previous life I manufactured race car trailers. Because they typically need lots of extra tires, spares, tools, and because race tracks could be long distances from home, enclosed trailers made sense. However, if all I'm doing is hangaring at home and hauling 10 - 20 miles to the airstrip, a purpose-designed open trailer seems adequate to me.

LarryT

Check out glider trailers

This has been mentioned in other threads, but if you want to build a trailer for an airplane, you should definately check out the enclosed glider trailers made in Germany. The best are the Cobra brand, and there are lots of them in the US. Most active gliderports will have a few of them on the field.

These trailers use a rubber cushioned torsion axle similar to the Torflex brand, and most are equipped with shocks. I have a 23-year old Cobra trailer that has hauled my Discus sailplane around the country for probably over 60,000 miles. The rubber cushioned torsion axles provide a soft ride (when they are properly selected to match the trailer's grosss weight), are maintenance free, and reliable. The glider and its instruments have been unaffected by the trailering.

I wouldn't consider any other style of axle for trailering an aircraft.

Airbag technical details.

This is from Joe at Airbagit

http://www.airbagit.com/Air-Bag-Brackets-s/1809.htm
http://www.airbagit.com/product-p/air-con-30.htm
http://www.airbagit.com/v/vspfiles/pages/AirBags_PAGE.htm
http://www.airbagit.com/product-p/shock-1000-t.htm

To get a soft ride, it is all about where you position the bags/brackets to achieve ride height at optimum pressure for the weight you have. I would assume very low pressure of perhaps 15-20lbs. The larger the bag diameter, the smoother the ride. I would suggest the DeNominator-II #2500 if you have room for a 6.25” diameter bag



I now have a 3D model of an RV 12 in sketchup I just need to work out how to post it

How wide is the wheel track on the 12? You might not be able to get it in between the wheels on the trailer.

No requirement for 2 axles

My former company manufactured a single rubber-torsion axle trailer that weighed 400lbs for the purpose of carrying Formula Ford (900 lbs.)and Sport Renault (affectionately known as "Sport Real Slow", weighed 1300? lbs) race cars. That trailer (trade-name "Formula Star by Haul-Lite"), with a mini-tire rack in front for an extra set of mounted tires, which then functioned as a stone shield, could be pulled by any FWD vehicle rated for 2000Lbs. towing capacity.

The trailer pictured above is significantly over-designed for the application of transporting an RV-12, IMHO. I did not have sheet metal forming capability at the time (1985 - 1991), so the trailers were made of welded steel tubing trusses. With sheet metal forming capability an aluminum trailer could be designed that would be (slightly) lighter. I suppose one could also come up with a design that Huck-bolted together so it could be sold as kit and assembled in a weekend.

LarryT

Grant Stewart said:

This is from Joe at Airbagit

http://www.airbagit.com/Air-Bag-Brackets-s/1809.htm
http://www.airbagit.com/product-p/air-con-30.htm
http://www.airbagit.com/v/vspfiles/pages/AirBags_PAGE.htm
http://www.airbagit.com/product-p/shock-1000-t.htm

To get a soft ride, it is all about where you position the bags/brackets to achieve ride height at optimum pressure for the weight you have. I would assume very low pressure of perhaps 15-20lbs. The larger the bag diameter, the smoother the ride. I would suggest the DeNominator-II #2500 if you have room for a 6.25? diameter bag

I now have a 3D model of an RV 12 in sketchup I just need to work out how to post it

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Back in August '08 there was much discussion about trailers. I made some simple 3D models & animations:

http://www.vansairforce.com/community/showthread.php?t=33597&highlight=trailer

lancef53 said:

How wide is the wheel track on the 12? You might not be able to get it in between the wheels on the trailer.

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The outside dimension of the wheels just fits inside the standard car trailer wheel with the fenders on. Several of us have had no issues moving them on car trailers to the airports. Vans must have figured that in.