Trailer Design - Resources?

[Kiwi303]

Laws differ by state in some ways. For example, in some states 8' 6" width is allowed only on some designated roads, otherwise it is 8’ 0".
And, aside from what is legal to operate on a particular road, do states have discretion regarding what they allow in a vehicle that is registered in their state?

Rederal laws don't generally give a set hard and fast size that states MUST use. They give minimums and maximums, States are allowed to legislate that state minimums are greater than federal minimums or state maximums are lower than federal maximums.

So the issue is when one state has a maximum at fed max, and the next door state has state maximums lower than fed maximums.

So if Fed says 9', State A says 8'6" and State B says 8'. Then 8'6" State A Trailers can be used on the Federal interstate in all states but not on State roads in State B.

 

[Topaz]

... If the trailer is enclosed and sealed why do you need to keep it in an indoor storage unit???

The short and pithy answer is that there's simply nowhere else.

If I put it in the garage, the 914 loses its home. I live in a condominium complex, so it's not like there's someplace else on the property it can stay. There are specific rules against storing trailers in the "guest" parking spaces on the property. It can't stay out on the street. Outside storage here costs almost as much as inside storage, and I already have the inside unit with drive-up access. I could leave it out at the airport, but that's extra-per-month to the tune of a tie-down fee, whereas putting it into my storage unit is essentially "free" in that it doesn't cost any more per-month than I'm already paying. The gliderport is also an hour and 15 minutes away. Not exactly conducive to fiddling with the airplane on a random evening.

So a variety of factors, really.

 

[Topaz]

I don't have any design resources, but I've had the misfortune to deal with a variety of home built sailplane trailers and fortune to deal with a number of name brand ones. Regardless I rig and derig almost every time I fly (now from a "homebuilt" Jiran half-clamshell which is the best of the homebuilt's I've run across) so I have a fair list of things I've noticed....

Outstanding post. Thank you! It's going to take me a little bit to digest all that, but I'm sure I'll be back with questions. I really appreciate all the information in this post.

 

[Old Koreelah]

Topaz there are some excellent ideas in your thread;
I built my aircraft carrier to suit the aeroplane, so didn’t have the flexibility you seem to enjoy. A few things I learned:

No matter how careful your design or your driving, your plane will get knocked about, especially during loading.

Use the same wheels on trailer and towing vehicle- more spare tyres.

No matter how light your trailer, you’ll need brakes- for parking at least.

Storing your plane at home on its carrier in a shipping container is inexpensive and may allow you to do some maintenance that was not possible while it’s assembled.

This is what mine looked like a decade ago; it’s been improved since:

 

[Topaz]

Topaz there are some excellent ideas in your thread;
I built my aircraft carrier to suit the aeroplane, so didn’t have the flexibility you seem to enjoy. A few things I learned:...

Wow! That's quite the ingenious rig! I love the pivoting crane to sling the fuselage onto the wings. Very clever.

Oh, and nice airplane, too!

 

[mm4440]

Hi Topaz, I have: "Trailers, How to Design and Build"; M. M. Smith, vol. 1 & 2. You can borrow.

 

[Victor Bravo]

Topaz, FWIW I have to agree with aivian on just about everything, especially for you to go and spend a few hours helping the local glass ship drivers put their gliders together and take them apart into the various trailers for comparison.

Yes the rear "tailgate" of the trailer can fold down flat and have the fuselage and wing dollies roll out of the trailer a foot or so. But at that moment, a gust of wind can put the wing root over onto the fuselage or off the trailer, because it will be very difficult to lock the dolly from flopping over to the side. Also, it will require a heavier structure for the tailgate, and it will require jacks on the tailgate and jacks or "feet" for the back of the trailer to keep it level. If you are building a tube or rectangular trailer, this becomes a good option.

 

[Matt G.]

... it will be very difficult to lock the dolly from flopping over to the side.

This design was chosen for my trailer because the dollies are captive in the trailer. They cannot roll out the end (stops not yet installed in this photo) and cannot tip out the side, either.


Topaz-

My trailer weighs around 1450 lbs, the glider weighs about 540 lbs if I remember right.

I am very happy with my construction method for the clamshell top, and would definitely do it that way again.

 

[PMD]

Thanks, that works!

However, we're getting into duplicates now. Karmarepair posted that same document in post #8, and I realize in looking through my OneNote notebook that I've gotten the Timbren "rubber block" axle-less suspension twice now, as well.

Pretty sure that's for inter-state commerce; the big commercial tractor-trailer rigs. As Vigilant1 notes, for non-commercial trailers I believe that each state has its own rules for motor vehicles. There are certainly some federal rules as well but, as is overall, states have priority where federal law doesn't apply.

IF you were to go with rubber block suspension (that as a trailer builder I strongly reccommend AGAINST!!!) Timbren is leagues above Dexter (who, BTW, own almost every axle manufacturer in this market). Rather than start kludging up shock mounts, take a look at their tandem walking beam if you want a simple bolt-on solution with FAR MORE TRAVEL than any other OTC "trailer" axle. Timbren Silent Ride Tandem Axle Truck Suspensions - Suspension for Trailers ANY single axle rubber based suspension is going to be VERY stiff and count on internal friction for some dampening. Again, if you want decent ride, you need air - but OTC air are for much heavier loads. Piece of cake to build something from small air bags though.

The simplest thing you could imagine was the old VW type I shown earlier) but that was for something around 1k lbs. not 2k. It is made from a "T" shape of two pieces of flat bar and can simply be cut, two more pieces splice in and welded back together to get whatever width you want without much fuss about alignment - but at 2K far too light. 2 of them would work, but you are back to the same problem as trailer suspension - old school adjusting bearings, seals, etc. and wheel/tire sizes getting hard to support. Also, as I mentioned earlier, brakes a good thing for highway, but since you are going only a few miles, not worth the bother at 2k.

As for regs; there are CMVSS and USMVSS federal standards in Canada and USA that apply to trailers. They "divide" similar to the trucking world at 26,000 lbs. and below that are nearly unknown and unenforced. As you have concluded, each state and province has their own take that easily pass USMVSS since those standards barely exist. For example: there is NO braking performance standard for U/26 trailers in the US, so NATM and its more ethical members build to and advertise a CMVSS standard that DOES exist (but is marginal at best....laughable if you have any understanding of motor vehicle safety). Side note: there IS an SAE committee studying this question/bigproblem, but they are years away from publishing anything (that will normally be adopted by Feds).

 

[Mike W]

Do the Plank's main gear tires pass between the trailer's wheels/fenders for loading and unloading, or is some other magic going on with that cross-trailer channel that they are both sitting in? I'd guess that everything comes off the back of the trailer, rolling on the channels shown.

Thanks.
PS: Cool Jaguar in the background! They gave admirable service for a long time.

The trailer is normally for transporting motorcycles to sporting events. It has a cross frame bolted on to support the aircraft on it's main wheels and a front wheel support beam.

We load the aircraft from the tow bar end with the trailer removed from the car, as the tyres are too wide for the trailer wheels. A tube is passed through the spar tube to lift the aircraft with someone supporting the front.

The wing carrying assembly is slid off the roof rack. A bit of a struggle. For short journeys we take two cars, one pulling the wings on a low boat trailer.

 

[tailwind]

Can you illustrate a walking beam design for light axles?

 

[reo12]

Having just transported 2 planes over 100 miles using a trailer - this is a nice string.

I used a modified American Aircraft open Falcon UL trailer. These were purpose built with a flat bed and framework with rigid wing pockets to support the wings and the canard on top. The trailer's18ftx75"wide open flat deck originally had 1/2" wood sheeting (osb when I got it - now 1/8" steel ) The frame is 2"x4"x1/8 rectangular steel tubing. Cross members are 2x4 tube on the ends. Then 2x2 tube where the upright frame mounts and some 2"channel on 4ft centers.

The axle and springs are light duty - I think they were rated for 1250 or 1500lbs. Sorry - been too long since I read the tag. Tires are 13". Tongue is a V made of 2x4 tube.

I sawed the framework off flush with the deck. Then use loose pipe inserts to allow the frame to be placed back into location. I removed the welded in place wing pockets and made pockets out of carpet. I found it to be not tall enough for transporting the wings above the landing gear of the planes but made it work.

One significant issue of flat type trailers is the flexibility of the frame. The lack of side walls or framing leads to significant flex. This one visibly bows 3/8 to 1/2" over it's length when a 200lb person steps on the back end. The flex is very apparent if one jumps up and down on the trailer. This flex could present some problems with some wing cradles or tie down methods.

I've considered making an enclosed trailer for hauling/storing aircraft. One item I've considered using for side wall framing is pallet rack uprights placed on edge rather than upright. They are a truss design, stiff and quite lightweight.

 

[Topaz]

Hi Topaz, I have: "Trailers, How to Design and Build"; M. M. Smith, vol. 1 & 2. You can borrow.

Thanks, Murry! I'll take you up on that. E-mail or call me and we can touch base on both that and next-steps for ESA after the workshop.

Topaz, FWIW I have to agree with aivian on just about everything, especially for you to go and spend a few hours helping the local glass ship drivers put their gliders together and take them apart into the various trailers for comparison.

I'd love to. But the guys with the glass don't like to fly out of Skylark very often because of the dirt runways, and Hemet, Crystal, and Warner Springs are a long drive away. YouTube is going to have to suffice. I haven't started that search yet, but since everything that ever was is on YouTube...

 

[Hot Wings]

The short and pithy answer is that there's simply nowhere else.

Can't you call it a homeless shelter and just leave it wherever you want !?! .................not much sleep last night and haven't had my - tea - yet.

Spent a considerable part of the night designing in my mind a single legged suspension system for a sidecar to attach to a motorcycle I'm bidding on. A side car is a similar suspension problem. Anyway I thought I'd post yet another option for you to ponder:
First generation Mini rear suspension. The pic is hydrolastic but there is no reason airbags or the Mini rubber cones couldn't be substituted.

If I get the cycle I'll probably use a front strut/wheel from a Metro I happen to have with the strut turned 90 deg - serving as the trailing arm.
This isn't the first nights sleep I've lost due to thinking about a subject related to one of your threads.

 

[Topaz]

IF you were to go with rubber block suspension (that as a trailer builder I strongly reccommend AGAINST!!!) Timbren is leagues above Dexter (who, BTW, own almost every axle manufacturer in this market). Rather than start kludging up shock mounts, take a look at their tandem walking beam if you want a simple bolt-on solution with FAR MORE TRAVEL than any other OTC "trailer" axle. Timbren Silent Ride Tandem Axle Truck Suspensions - Suspension for Trailers ANY single axle rubber based suspension is going to be VERY stiff and count on internal friction for some dampening.

Thanks for the suggestion. That looks really nice. I'll have to see what range of loads they have those in.

The simplest thing you could imagine was the old VW type I shown earlier) but that was for something around 1k lbs. not 2k. It is made from a "T" shape of two pieces of flat bar and can simply be cut, two more pieces splice in and welded back together to get whatever width you want without much fuss about alignment - but at 2K far too light. 2 of them would work, but you are back to the same problem as trailer suspension - old school adjusting bearings, seals, etc. and wheel/tire sizes getting hard to support. Also, as I mentioned earlier, brakes a good thing for highway, but since you are going only a few miles, not worth the bother at 2k.

There's nothing magical about 2,000 lbs here, even though that's the number that's been bandied about here for example. In point of fact, with a ~450lb. payload of airplane and spare fuel cans, the entire trailer - loaded - is more likely to end up closer to 1,200lbs than 2,000.

I'm coming more and more to the mind of wanting a COTS solution for the suspension. It may not end up being the "best" solution possible, but the point Peter Hudson and TFF have made is very well-taken: Don't turn the trailer project into something on-par with designing and building another airplane. On a given flying day, I'm only trailering the airplane about 23 miles in each direction over very good roads and freeways. Maybe a 50-mile trip each way once a season if I leave the airplane and trailer at the gliderport for the best weeks. This isn't for cross-country moves, multi-thousand-mile trips, or off-road. As VB pointed out, having a little tow-plane bolted to the nose of my glider minimizes the odds of an outlanding and the Call-of-Shame for the trailer.

Please understand that I'm not being dismissive of your experience or expertise. You've been incredibly helpful in this thread.

 

[Topaz]

... This isn't the first nights sleep I've lost due to thinking about a subject related to one of your threads.

My work here is accomplished!

 

[Victor Bravo]

IF you were to go with rubber block suspension (that as a trailer builder I strongly reccommend AGAINST!!!) Timbren is leagues above Dexter (who, BTW, own almost every axle manufacturer in this market). Rather than start kludging up shock mounts, take a look at their tandem walking beam if you want a simple bolt-on solution with FAR MORE TRAVEL than any other OTC "trailer" axle. Timbren Silent Ride Tandem Axle Truck Suspensions - Suspension for Trailers ANY single axle rubber based suspension is going to be VERY stiff and count on internal friction for some dampening. Again, if you want decent ride, you need air - but OTC air are for much heavier loads. Piece of cake to build something from small air bags though.

PMD, how does that Timbren suspension work? I watched the video in the link, and did not see where the spring or shock absorption is. The trailing arm (you called it a walking beam) looks REALLY GOOD for this kind of use.

What is it about this type of suspension you do not agree with? Is there an air bag suspension with this same kind of trailing arm that you can recommend?

It seems to me that using one half of that Timbren mechanism (single axle)... or whatever you recommend that uses this style with an air bag... would work really well for Topaz' use.

 

[billyvray]

I'm not an expert on the Timbren. The info calls out hollow rubber bladders for the main support. Also there is an opposing rubber bladder on the front side that acts as a damper. No air bags. I've never seen it or how it works but it is interesting.

 

[Hot Wings]

My work here is accomplished!

I'm afraid it is a never ending affliction. If not you - than someone else.

PMD, how does that Timbren suspension work?

Looks to me like it is a mechanical version of the Mini Hydrolastic suspension?
Not the best explanation but it kind of gives the basics:

 

[PMD]

PMD, how does that Timbren suspension work? I watched the video in the link, and did not see where the spring or shock absorption is. The trailing arm (you called it a walking beam) looks REALLY GOOD for this kind of use.

What is it about this type of suspension you do not agree with? Is there an air bag suspension with this same kind of trailing arm that you can recommend?

It seems to me that using one half of that Timbren mechanism (single axle)... or whatever you recommend that uses this style with an air bag... would work really well for Topaz' use.

A walking beam is for two axles. The single arm is just a trailing arm with a carefully designed compression member and an opposing rubber member that gives non-linear rising rate and some good damping. The Timbren system for two axles uses a compound compression system with a second point of articulation on each side of the walking beam. Essentially two sets of the single system. What makes the walking beam SO much better than a single trailing link is considerably more wheel travel = lower effective spring rate for single deflection, but much high spring rate for double deflection (i.e. lateral acceleration).

Hot Wings got this exactly right - a mechanical version of hydrolastic. Except, IIRC, Minis never used that (just single acting rubber "spring". It was the larger cars (I think beginning with the Austin 1100 - sold later over here as the Austin America) that tried it. Don't think it actually worked very well, and I think they missed the big one by not providing a flow restrictor for braking loads. If you want to see what in my mind is the most elegantly engineered non-driven bit of vehicle suspension - look at the tandem rear axles of the GMC motorhomes of the '70s. There is a leading link at the rear and trailing link ahead, both bearing on a single horizontal air bag. Gave all of the advantages of a walking beam plus all of the advantages of air suspension. BRILLIANT.