Easy hoist for enclosed trailers

dunc

RAF/Sparrowhawk/SC 2.5 FI
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1967 Turbo/RSTOL/VG Cessna 185 Skywagon, 1946 Grumman TBM Avenger
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I am considering this design, mounted to the side of an enclosed 20 ft x 7.5 ft tall trailer. The hoist would be stowed flat against the side of the trailer while driving. It is then swung out perpendicular from the trailer, lifted, and secured tight at full height. Rotor is to be assembled and inspected on sawhorses below the boom end, while parallel to the trailer. It is then hoisted fully upwards, clearing the gyro mast height. The gyro is then rolled below the rotor, and the rotor lowered slowly to align the single bolt holes.

Bottom line
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I am looking for a engineer's structural design help in calculating whether 1-1/2 inch tubing of 6061 T6 aluminum (or ?) can adequately support a 100 lb rotor weight with a reasonable safety margin, or do I need to use larger diameter tubing?

Trailer Crane Design 2.jpg
 

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wolfy

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You don't say the wall thickness, but I would say even with a very light wall 1-1/2 tube would do it in spades. I'm not an engineer though:)

wolfy
 

BEN S

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Suggestion. Make a welded cradle on the top piece that the hub bar two blocks into. If you are trying to assemble on even a slightly windy day alone, you will thank me in spades.
 

Aerofoam

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I would consider 2 lifting arms about 7ft. apart. They could be simple inverted L shaped arms from 1" square steel and drop them into 2 sockets that stay attached to the trailer sides. Pop out the arms for transport. Each arm has a small pulley and line with a cam cleat on the socket.
Assemble the blade sections and hub on the ground, then lift it up alternately, so you don't have to lift the entire weight in one shot.
You could also have a small crank winch (boat trailer type) to lift both at the same time.
As for your single arm, not much benefit in AL over steel, but either one, even in 1/16" wall would handle 100lbs.
Your use of a knee brace puts most of the stress on the top trailer mount. Make sure it is attached with structure and use large fender washers to support the tensile load pulling away from the trailer wall.
 

dunc

RAF/Sparrowhawk/SC 2.5 FI
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1967 Turbo/RSTOL/VG Cessna 185 Skywagon, 1946 Grumman TBM Avenger
Total Flight Time
5000
Wonderful suggestions all so far!

Ben S - I have about two years experience with my RAF rotor assembly on sawhorses, then using a remote controlled electric ATV winch mounted to the boom. See that collapsible hoist image below used with open trailer. This is way over-built and capable of 1000 lbs. Also a quick press on the winch remote control moves too much for the fine motion control needed to align and insert the rotor pivot bolt. I keep one blade tethered to keep from swinging.

Brian J - 1st step would be to loosen hoist mast wall clamps, rotate until boom is perpendicular to trailer wall, lift hoist upwards 4 feet via the lifting handle, and then tighten the mast clamps using thumbweel bolts. The whole hoist would only weigh about 11 lbs if 1/8" wall, or half that if 1/16". Then attach 100 lb rotor via nifty-lift.com block and tackle which has 4:1 ratio, so only 25 lbs pull required to lift rotor to top. This block and tackle unit has marine style cord grip to lock the cord. Once fully hoisted, position gyro and a 10 ft ladder for myself to stand upon to adjust position and insert the rotor pivot bolt.

Aerofoam - I think your design is much more complex, with difficult, and time consuming assembly. ;^) Aluminum is much stronger per pound vs steel and does not corrode. I will surely use a large drilled and tapped flat plate for backing the mast clamps and mount through the trailer wall ribs.

Keep the ideas coming guys!

20190831_113108.jpg
 
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Aerofoam

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Aerofoam - I think your design is much more complex, with difficult, and time consuming assembly. ;^) Aluminum is much stronger per pound vs steel and does not corrode. I will surely use a large drilled and tapped flat plate for backing the mast clamps and mount through the trailer wall ribs.

Complicated?
2 arms instead of one, no pivot, they simply drop into slightly larger square steel, or Al sockets. This is as simple as it gets.
If you think it is complex, I did a poor job explaining, or you just are not understanding what I said...
I could build these arms in less than an hour.

Al is strong enough and lighter in many applications, but it also has to be thicker because of very poor fatigue issues and welding is more difficult with the added hassle of needing heat treating afterwards if you want to get anywhere near the original per-weld strength at the margins.
For many applications such as this one, the thinner steel tubing is easier and not heavier (If you bumped up to 1.5" it wouldn't need the knee brace).
I would estimate each arm to be about 3lbs. max. so is weight an issue?
I use aluminum all the time and would consider it for this application if I were using cheek plates and bolts, but welding the steel tube would be so easy and fast......
For me it would ultimately boil down to which material was in the in rack that matched the size specs. needed..
I would stick to a manual block and tackle, a small boomvang assembly off the shelf, or small manual winch as to NOT have the added complexity of having to run something electrical for an electric winch to lift only 100lbs. If the winch or tackle is utilized, you could use a single arm, but then you don't have stability of the hanging object. I think I would stick with 2 arms just to keep it from swinging around in the wind.
Pivot, removable, folding, whatever, that's personal preference, I like the simplicity of a socket, and nothing else hanging on the outside of the vehicle when not in use.
 
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dunc

RAF/Sparrowhawk/SC 2.5 FI
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1967 Turbo/RSTOL/VG Cessna 185 Skywagon, 1946 Grumman TBM Avenger
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Aerofoam - Unless I don't understand your suggestion, the "complex" assembly part to me is lifting each inverted "L" to the upper square bracket and dropping through square hole. This means balancing an 8 foot inverted "L" while standing on a ladder as the top bracket is in the air about 8 ft. Then inserting the bottom into a lower square socket(?) Times two. Plus the rigging.

I was already thinking 1.5 AL tubing with .125 wall, but this was exactly where I was looking for some structural engineer to help calculate elastic strength. If I uses a simple mast/boom "L" (no brace) this is 12 linear ft of 1.5 square steel, at .120 wall that is 2.2 lb/ft or 26 lbs with a long lever arm! No rack here - so I will have to purchase any material required regardless, and the cost difference is negligible overall.

You may not have read the planned simple small block and tackle part. We both certainly agree on the "no electric winch" part. Been there, done that. Raising that mast with the electric winch and upper diagonal brace attached as as seen with my RAF gyro is "just about" all my skinny 72 y.o. arms can handle! All the wiring was done through the square aluminum tubing, and using a small electric towing brake battery charged through the trailer cable. Looks nifty, and works, but way too much effort to get the side sway braces and all attached.
 

Aerofoam

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I am thinking the arm is only 4ft long with about a 2ft. vertical component to drop into the fixed tubes.
If the angle was 45deg. instead of 90deg. the arm would be about 6ft., but the post could start about 2ft. lower on the trailer as to not have to
climb and it would be fairly light. Probably about 8lbs out of 0.250" wall,or the same for 0.093" steel.
I was not envisioning the long post component, and with 2 arms at whatever distance, the load is cut in half and the stability actually exists.
The arms could be 0.062 wall x 1" square steel, 4lbs.ish maybe? Very easy to set into sockets at the 6' level and throw back in the trailer when not in use. the rigging could just be a welded loop on the arm with a haul line. (maybe to a single point with a winch, or boomvang.) Many options...
I ditto the overhead lifting, I have a hard time with the 24' dragon wings on my AC. and am thinking about building a folding mast that folds 6" above the seat "sideways" to put the rotor at chest height for assembly.
 

dunc

RAF/Sparrowhawk/SC 2.5 FI
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1967 Turbo/RSTOL/VG Cessna 185 Skywagon, 1946 Grumman TBM Avenger
Total Flight Time
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I had to look up boomvang. Although i learned a new word, not sure how to select or use one for my application.

The end of the horizontal boom needs to be at 12 ft high in order to leave room for block and tackle and rotor support. I use a 1.5" square aluminum tube with a downward eyebolt at each end, and upward eyebolt in the midde attached to the hoisting line. The end eyebolts are attached to ropes loopedcaround each rotor blade. The horizontal boom is 4 ft long to extend to middle of gyro with sufficient clearance for its wheels vs the trailer.

Later I plan for a fold-out 10" deep work bench on the full length outside trailer wall to be used for rotor assembly. Then I can stop carrying the sawhorses.

I see you have a single place SC. I have always wanted to fly a light single gyro just for fun. Maybe my next one!
 

Sv.grainne

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Dunc:

Block selection pretty straight forward, I can post some pics and details if you are interested. Double block with Becket and double block. Bought from Garhauer Marine, got line from Amazon.

Bobby
 

Aerofoam

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Pteradactyl, AC 447/503, too many UAVs
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The boomvang tackle can be bought as a single unit that snaps on with shackles at both ends, it is usually triple, or even quadruple purchase with a built in cam cleat on the loose end.
You could have an upper and lower attachment point on the side of the trailer and the line, or lines from the boom would clip in so the pull would be vertical and downward along the side of the trailer, the boom lines could live with the booms....
 

Sv.grainne

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The boomvang tackle can be bought as a single unit that snaps on with shackles at both ends, it is usually triple, or even quadruple purchase with a built in cam cleat on the loose end.
You could have an upper and lower attachment point on the side of the trailer and the line, or lines from the boom would clip in so the pull would be vertical and downward along the side of the trailer, the boom lines could live with the booms....
Just easier to buy the hardware IMO.
 

Aerofoam

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Az.
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Pteradactyl, AC 447/503, too many UAVs
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Over 3k....(From the ground !)
This is simple and more than adequate for a light load like 100lbs.
The components cost more separately than as a assembly, this is the first one that came up, so you can find it for less on Ebay...

 
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