Trailer Loading Geometry

dunc

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My RAF purchase included a 12 ft tilt bed trailer which has now been used a couple times. Each gyro loading time is a real problem due to its four wheel geometry (nose, mains and t/w). As soon as the front wheel is raised, the tail wheel is grounded and all the weight shifts there. Generally one of the main wheels becomes airborne as the gyro teeters forward via electric winch or muscles. It is never "easy".

I reviewed many nice gyro trailers in the forum, but this common loading problem is not addressed. Of course many makes and models do not have the tailwheel just a couple inches off the ground as the RAF does. So I must be missing something simple, like using different ramp lengths, or ???

Can one of you experienced towing gyro gurus help me out? Pictures might help.
 

AirCommandPilot

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Make some ramps for the main gear only so they raise the machine off the ground a bit before the nose wheel starts rising onto the trailer. This will allow the tail wheel a little room to drop as the machine is pulled onto the trailer.
 

dunc

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Since the main gear are five feet behind the nose wheel, does this mean like an eight ft (or longer) main gear ramps combined with a three ft nose wheel ramp? It would still seem that for each foot moving in towards the trailer, the nose wheel will rise faster than the main gear due to higher ramp angle, thus still cause the tail to move downwards. Maybe I should have paid more attention in high school geometry class. I'd like to know what works before buying ramps as a practical geometry experiment. <smile>
 

Brian Jackson

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Great thread Duncan. I've been sketching a design for mine for a while and ended up similar to what AirCommandPilot describes, although it's 3 ramp planes that all run parallel at the same slope angle, the outer 2 starting 5' or so farther rearward, and the level-off "peak" points are also 5' offset so the ship stays keel level along the entire loading path.
 

Vance

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There is a lot of information missing before someone could calculate how long the ramps need to be such as how far does you trailer tilt, where does it tilt from and how high it the deck.

The basic concept Bobby advocates simply allows the aircraft to rise up the ramps on the mains before dealing with the nose wheel.

I was never good at math so I would simply make a sketch of the important bits with long ramps, cut the parts out and to see where the nose wheel ramp needs to be.

The RAF is easy because it is so light on the nose bear it is easy manage. The tail wheel is fairly far back and strong.

You may even be able to get by with a little standalone nose gear ramp or simply handle the tilt manually.

Good luck with your project and your aviation adventure.
 

dunc

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Vance - Rereading Bobby's reply shows that you better understood it that I did. However I still don't see how it would work. While the two ramps raise main gear, what does one do with the nose gear? Let it stay on the ground until just before the trailer's edge then (manually?) lift it onto the trailer? Using scale paper-doll cutouts was going to be my next step, assuming I learned nothing from the Forum.

I think Brian's reply mirrors an earlier thought. See my sketch, not to scale. The outside two main wheel ramps start 5 ft from where the center nose wheel ramp starts, and all three level out at the same point. The horizontal distance "x" can be as short as desired.

Another wild-ass thought was to cut the trailer bed into three lengthwise parts, keeping the outside two full length, shorten the center section by five feet and adjust its fulcrum point to touch the ground. Too much work! This has to have been solved many times by Forum membrs.

My trailer bed is 12 ft long, with the tilting fulcrum point is 58" from the front, the wheel axle is 70" from the front, and the bed is 16" above the ground when not tilted.
 

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AirCommandPilot

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If the bed does not hit the ground when tilted, Just add a shorter nose wheel ramp like you drew up.
 

Vance

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Your sketch looks like what I imagined Bobby was recommending.

When we unloaded an RAF from a box truck I was impressed with how easy it was to tilt.

I have a single axle trailer for The Predator and use a crane to lift The Predator on to the trailer. I would not recommend this scheme. The challenge I was trying to manage is the track of the trailer is the same as The Predator and to balance the trailer correctly The Predator's mains need to be ahead of the fenders. Fortunately I seldom use the trailer so I have not been motivated to improve.

I have seen tilt trailers that tilt from the hitch making it easy to load anything. This would be my preference.

Given your situation I would just diddle around with various loading schemes till you find one you are comfortable with.

The key to success on a limited budget (time or money) is to keep an open mind and just solve the specific challenges you have.
 

dunc

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Bobby - the bed does indeed hit the ground when fully tilted, but not sure how that helps? That's why I sketched the non-tilted configuration. i.e. if the nose wheel is placed on the bed while at ground level, the mains are also at ground level, and there is no main wheel "ramp" to connect to the end of trailer bed. If the bed is then forced upwards from the ground, thus lifting the nose wheel, then the tail wheel quickly hits the ground and the mains will also be quickly elevated as it is solely supported by nose and tail wheels respectively. I suspect a similar scenario still occurs should the main wheel ramps be attached forward to the end of the bed.

Vance - "tilt from the hitch" - does that mean the front of the trailer bed hits the ground? Not sure how the box truck experience was achieved, unless a power lift gate was used? Do you recall? Otherwise seems like the same geometry. I understand that it does not take much downward force on the keel to lift the nosewheel.

Another of my simpler thoughts was to attach an electric winch cable to each of the main wheel struts, and use ~10 foot ramps. One then needs to lift the tail while being winched forward to keep the keel relatively level until the nose wheel rests upon the trailer bed. A removable extension would give some mechanical advantage in controlling the tail to keep it "level". Still sounds like a scary two person job.

I was hoping to have success by asking a simple question to the vast knowledge-base represented here, buy some material and a winch and be done by the afternoon. I have another month before our next gyro "road trip".
 

Vance

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Tilt from the hitch means that the hitch stays the same height and somehow the axels get out of the way.

We backed the box truck up to a high curb and used two six foot motorcycle ramps. We balanced the aircraft on the mains and rolled her down the ramps. The nose and tail wheel were briefly in touch with the ground at the same time slightly unloading the mains.

I am sorry I am not more knowledgeable about trailers. I feel it is a great way to shake an aircraft apart and put most of my energy into giving her a soft ride.


Occasionally I have a client who wants to trailer their aircraft in for training. I rent out part of my hangar instead.
 

Uncle Willie

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dunc;n1138677 said:
... My trailer bed is 12 ft long, with the tilting fulcrum point is 58" from the front, the wheel axle is 70" from the front, and the bed is 16" above the ground when not tilted.
It looks like you have about a 12° ramp to climb but do not have 12° of clearance under the Gyro.
Give us the numbers and we'll design you a set of ramps!

Confirm these...
Height of Trailer Bed above Ground on Lever Surface = 16"
Distance from Rear of Trailer Bed to Trailer Axle = 74"

Now all we need now are the Aircraft dimensions.

Distance from the Main Gear Axle to the Nose Gear Axle = ???
Distance from the Main gear Axle to the Tail Gear Axle = ???
Clearance under Tail Wheel on a level surface = ??? (Or Nose Wheel but state which it is.)

This fellow has the same issue to a minor degree.
Notice how the tail wheel digs into the grass as the Nose wheel climbs the ramp until the Main wheels reach the ramp.

https://www.youtube.com/watch?v=r4d_ev6UmWI
 
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dunc

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Tilt from the hitch sounds interesting. Was it then hydraulically lifted back to level? Great idea for cars, etc. If only I had room on the trailer for carrying a high curb!

My paper doll engineering exercise, using graph paper, showed that using two ten foot long main wheel ramps, plus a five foot long nose wheel ramp, may work nicely and not using the tilt bed function. These would easily stow on the 12 ft trailer bed. Now I need some materials engineering to determine thickness and temper of aluminum channels that will hold the 800 lb gyro (400 lb per main wheel). I note sveral "arched" ramps are offered commercially on Amazon, but hard to approximate this effect on paper. It is also difficult to approximate the effect of real world tire pressure.

My whole reason for getting a gyro is for nationwide touring behind the RV. I understand your prima facie opinion about gyros being shaken apart during trailering. Are you aware of any crashes or repairs that were a result of such treatment? The opinions concerning rotor removal for transportation was especially interesting. I am not sure my new RAF will be the final solution, but I expect it will be the beginning of a beautiful relationship (Bogey, Casablanca)
 

AirCommandPilot

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Something like this. A few 2x6s about 8' long layed under the main gear wheels about 2 feet up the end of the trailer should give you the clearance needed. The front wheel will just ride up the center of the trailer.


RAF.PNG
 

dunc

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I like this, Bobby. I think I have some scrap around to give this a try. Is this image done to scale, e.g. AutoCAD?

I had tried something similar with some shorter aluminum ramps I had around. The tailwheel still hit forcibly. It also proved that the ramp ends need to be secured to the trailer bed, and "hang on" as the gyro went past the trailer tipping point. The full bed tilts on my trailer. You have the fulcrum placed pretty close.
 

dunc

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Uncle Willie - I REALLY liked the video on the fast loading SC trailer setup. Do you know if the owner/operator is still around? Contact info? The setup looks almost perfect for me - assuming I would choose to tow with rotor attached - although I am not sure about my SC rotor length overhang interfering with the RV without lengthening the trailer tongue. Do you know if he use a canvas or other cabin cover? The gas shocks looked like a great addition, and easy too. I am also considering adding shocks the trailer axle which has only springs now.

My RAF/SH conversion has 60" between main and nose gear axles, 57" from mains to tailwheel, and about 3" of tailwheel clearance

I will bet that Antonov AN-2 in the background is the only aircraft at that field that can "maybe" take off shorter, or fly as slow as any gyro. They are an incredible aircraft and too bad the FAA won't allow them to fly commercially. They are not cheap to fly however!
 

Vance

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dunc;n1138690 said:
Tilt from the hitch sounds interesting. Was it then hydraulically lifted back to level? Great idea for cars, etc. If only I had room on the trailer for carrying a high curb!
We were just lucky to find a high curb and borrowed the ramps.

They use them at Bonneville because most of the cars don’t have much ground clearance.

They use hydraulics or air to return it to road height.

Imagine if you had a drop axle and could compress the springs the tail would be on the ground.

I feel you are making progress so let's not get side tracked.

Building that sort of trailer is a big project.

If you have a typical trailer it will have way to much spring and no dampening so those are the things I would work on if I was planning a lot of trailer miles.

I am a take the rotor off enthusiast.
 

Uncle Willie

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OK, this is to Scale based on the numbers you supplied.
With only 3 inches of clearance, a 2x6 is not going to do it.
3 inches means the wheel hits the ground at 3° of tilt. Almost nothing!

You are trying to drive the tail wheel 9.5 inches into the ground so the ramp will need to be at least 10 " tall at a bare minimum. 12" would be safer.
The wheels are 5 ft apart and you will need to get up the ramp in 4 feet.
That makes the ramp 9 ft long overall.

Remember the ramp is only for the Main wheels. The nose wheel ramps up the trailer bed.

GyroTrailerRamp.JPG
 
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Eric S

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Dunc,

Maybe try flipping the tailwheel bracket and see if it helps your clearance. On my RAF Sparrowhawk, the front bolt hole is offset, so when you flip the bracket, the tailwheel is raised approx. 1"-2". I flipped mine and it gave me better ground clearance for more aggressive landing flares. You know, like all proper gyro landings should be!! I will probably end up making a custom tailwheel bracket someday to raise my tailwheel as high as possible so the rudder will just barely clear the runway on landings. Here's a pic I saved where a guy trimmed the bottom of the tall tail at an angle so the tailwheel can stick straight out the back. Trimmed tall tail pic.jpg

Eric
 

Eric S

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Dunc,

You might simply swap your tailwheel for a smaller one for more ground clearance. Here's a pic of mine that was taken before I swapped the tailwheel bracket for additional clearance.

Eric
CIMG1670.JPG
 
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