aircraft trailer secrets › members › seaplanetrailer... · 2019-10-30 · under the aircraft...

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Seaplane Trailer

Secrets In this special report, we’re going to take an in-depth look at seaplane trailers. We’ll discuss three major designs with basic drawings and explanations of each so you can build your own trailer for your aircraft. The fist design we’ll discuss is the oldest and simplest design, the flatbed trailer. Next we’ll take a look at the most recent and versatile design, the hydraulic lift trailer. We’ll take a quick look at a manual lift trailer. Finally, we’ll cover a cheap and portable alternative, the manual dolly.

Don’t get caught high and dry!

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Flatbed Seaplane

Trailer

Side view of a flatbed seaplane trailer.

The most common (and maybe worse) seaplane trailer design is the flatbed trailer. The flatbed trailer has a couple of advantages but it also has some substantial disadvantages. Let’s take a look at these:

Advantages

1) Very cheap to buy or build. 2) No special mechanical/movable parts to break.

Disadvantages

1) You can’t easily get the aircraft off the trailer. 2) The length of the tongue makes it difficult to

put in a hangar and close the door.

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3) The trailer adds an additional 2 feet of height to the aircraft, making clearing the door opening of almost any hangar very difficult.

4) Aircraft weight is supported by the float keel, which can cause leaks. The flatbed trailer can be a cheap, easy solution if you’re just looking for a trailer to pull your aircraft out of the water for the winter or for maintenance. If you intend on putting your aircraft in a hangar be careful. Unless you have a lot (14’ + depending on the trailer and aircraft) of vertical door clearance in your hangar you may not be able to get your aircraft in. In addition to that, it’s difficult to remove the trailer from under the aircraft. If you leave the aircraft on the trailer, the trailer tongue may extend past your doorway, making it impossible to close your hangar door. If you don’t have a door on your hangar yet and you own a seaplane, there are some special considerations you need observe. Check out our website at http://www.HangarDoorSecrets.com for more information on hangar doors designs. It’s a good idea to attach flags (the ones on fiberglass poles from a bike shop work well) to the rear corners of the trailer so you can line-up the aircraft with the trailer when the trailer is submerged under water. Also, to alleviate the potential float keel damage from a flatbed trailer (and for greater friction for towing take-offs), you can build “V” shaped cradles on the deck to support each float. If you leave your plane on a flatbed trailer and tie it down outside, be very careful. Be sure to chock the trailer wheels so the trailer can’t sway back and forth in heavy winds. Also, be sure to put supports to carry the weight under the front, rear and sides of the trailer. You need to do this for two reasons. First, if the wind causes the weight of the aircraft to shift on the trailer, the trailer could tip and the plane could slide right off the trailer. I’ve seen cases where this has almost totaled the aircraft. Secondly, if a tire goes flat the trailer could list to one side and with a little wind, your plane could slide off. Even if the aircraft stays on the trailer, you would likely break the bead of the tire, forcing you to jack up the trailer and aircraft. The final consideration if you intend to leave the aircraft on a flatbed trailer outside is to clearly mark the trailer tongue. I’ve seen cases where a vehicle has not seen a trailer tongue and ran right into it. If this happens while your plane is on the trailer, you risk sever damage to the aircraft. As ugly as it is, it’s best to wrap the entire tongue in florescent survey tape or reflective tape and place an orange construction cone at the end of the tongue. It’s best to never leave a seaplane on any trailer for an extended period of time. If you have an overhead hoist in your hangar so you can lift your plane and pull the trailer out, a

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flatbed trailer will work fine. Apart from that, you may want to consider a hydraulic lift trailer. It’s much more versatile.

A small flatbed seaplane trailer is a simple solution for a light seaplane like this experimental Kitfox. Stay away from the small (usually red) folding trailers you can buy at hardware stores. They are designed for less than 900 pounds and can be extremely

dangerous if they’re overloaded…

A heavier-duty flatbed trailer like this one will work well for most small to medium-sized seaplanes. Be careful with

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the wheel-well design. If the wheels protrude above the deck as in this example, the floats may not fit. If you build your own flatbed trailer, build the deck over the wheels like the example below…

There are many commercial manufacturers who build flatbed trailers suitable for seaplanes. A commercially manufactured flatbed trailer like this one above can be

purchased for around $5,000 but it can be built for much less…

A framework cut-away shows the very simple steel frame of a flatbed trailer. The deck can be made of steel or wood. Steel is the strongest and longest lasting but can be very hard on the floats and the slick surface makes it easier for the aircraft to slip off of the trailer. Wood will deteriorate over time but it’s less likely to damage the floats. Our

favorite design is a steel deck for strength and lifespan and wood runners attached to the steel deck to save the floats. These runners can be replaced when they rot or sliver

without affecting the strength of the trailer. Additionally, “V” shaped cradles on the deck to support each float will reduce the possibility of float keel damage.…

You can access a full list of suppliers for the axles, wheels and other flatbed trailer parts on our website at http://www.SeaplaneTrailerSecrets.com/members/parts.html

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Hydraulic Lift

Seaplane Trailer

Side view of a hydraulic lift seaplane trailer.

The hydraulic lift seaplane trailer is one of the best and most versatile seaplane trailers in existence. It’s relatively easy to build. Let’s take a look at some of the advantages and disadvantages of this design:

Advantages

1) Can be used for multiple aircraft – perfect for FBOs. 2) Hydraulic lift capability makes it easy to both lift and drop the aircraft from

the trailer. 3) Can add as little as 2” to the height of the aircraft for hangaring. 4) Won’t create leaks by damaging the float keel like a flatbed trailer.

Disadvantages

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1) More moving parts to break. 2) More difficult to build. 3) More expensive.

The hydraulic lift seaplane trailer is really a slick design. Think of it as a narrow boat trailer with a hydraulic scissor lift that lifts the aircraft from the float spreaders. The hydraulics can either be electric or manual. One word of caution; the hydraulic lift seaplane trailer lifts the aircraft from the float spreader bars. Not all spreader bars can handle the full weight of the aircraft. Please consult with your float manufacture before lifting the aircraft by the spreader bars. Let’s describe how it works. Let’s say your plane is in the float pond and you want to pull it out to do an annual inspection. All you need to do is back up and hook this trailer up to your truck like a normal boat trailer. While you’re on flat ground, raise the hydraulic scissor lift to its maximum safe height either with the electric hydraulics or by pumping the bottle jack. Once the scissor lift rails are up, back the trailer into the water until the base of the forward bump-stops are just below the bottom of your float spreader bars. Pull the aircraft snug to the bump-stops and secure with the spreader bar locks (see pictures below). Then, simply pull the trailer out of the water just like a boat. Once you’re on level ground, you can lower the scissor lift rails a little to keep the aircraft from being too top heavy on the trailer. Back it into your hangar and release the spreader bar locks. Throw a couple of old tires under each float and slowly release the hydraulics, setting the aircraft down on the tires. Then you can pull the trailer out from under the aircraft and park it wherever you want (it’s best to pull the trailer out by hand so you don’t risk driving out at an angle and damaging the floats). To move the aircraft again, simply back the trailer under the plane until the spreader bars touch the bump-stops (again, it’s best to do this by hand so you don’t damage anything) and lift the hydraulic scissor lift with the electric hydraulics or by pumping the bottle jack. Secure the spreader bar locks and you’re on your way. Here’s an important note. Whenever you’re pulling the aircraft from the water or launching it, it’s important to keep the scissor lift at its maximum safe height so you don’t risk driving the floats into the ramp.

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Here’s a drawing of a basic hydraulic lift seaplane trailer. The lift rails are typically directly above the wheels and are designed to lift at the furthest outboard width of the float spreader bars close to the floats themselves. The wheel span of the trailer needs to be narrower than the inside of the floats of the smallest aircraft you intend to move. This way the floats can be set on the ground without interfering with the trailer. Note the bump-stops with the spreader bar locks on the front of the rails (close-ups below)…

This same trailer as above that may have been built specifically for a Cessna 206 on floats can be modified to accommodate a Beaver on floats by simply adjusting the rails outwards to fit the wider floats (assuming the axle, tires and trailer frame were designed

for the heavier load). A close-up drawing of the adjustable width rails is below.

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A close-up from above of the extendable cross-members shows how the rails can be extended by simply pulling out the pins and moving the rails narrower or wider. The cross-members must fit snuggly into the receivers attached to the rails. If there’s too much slop the receivers could split open, dropping the aircraft. Note the dotted lines

showing the cross-member stop points. If the cross-members are not set deep enough in the receivers at the widest opening, the receivers could split and fail. At the narrowest opening, the cross-members can not protrude past the outside of the rails or they could damage the floats. For pins, we use the standard trailer hitch pins with cotters available from any auto parts store. A side view of the bump-stop and spreader bar lock is below.

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A side view of the bump-stop and the spreader bar lock. The bump-stop is nothing more than a vertical stop covered with carpet. The bump stop should be approximately 50%

taller than the thickness of your float spreader bars. The bump stop bolts to the rail and is adjustable forward and back to allow for different aircraft with different center of gravities. You want the center of gravity of your aircraft to be approximately 1 foot forward of the center of the trailer axle. Measure the distance between the front of the

forward spreader bar and the center of gravity of the aircraft. Take that number and add 1 foot. Then measure that same distance from the trailer axle forward and bolt the bump-

stop to the closest hole. The spreader bar lock is simply an L shaped hook that bolts to the bump-stop so that it can pivot up and down. The top length of the lock (horizontal piece above) should be approximately 1 inch longer than the width of the forward spreader bar to allow for padding and a little slop. You can use some fuel line to slip over the spreader bar lock for padding. You may want to consider putting springs on your locks to keep

them from releasing if you hit a bump. Also, be sure you mount the locks on the inside of the bump-stop (closest to the center of the trailer) so they don’t conflict with the floats. To open, just swing the lock open so it lies backward. Once you have the spreader bar

tight to the bump-stop, swing the lock over the spreader bar on both sides and the aircraft is secured to the trailer.

A simple bump-stop and spreader bar lock…

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Above is the sample framework for the hydraulic lift seaplane trailer. Notice the center rails (box shaped) for the scissor lift. These rails need to be much stronger than the standard trailer framework since these two rails will hold the entire weight of the aircraft. See the pictures below for more detail of the scissor lift rails. Apart from the scissor lift rails, the following is a general guideline for the steel gauge to be used for the trailer framework based on aircraft weight. Again, these are generalized guidelines, have an engineer review your plans before you build. We always suggest you overbuild your trailer for two reasons. First, it’s not worth risking the entire aircraft to save a couple of bucks and secondly, it’s more versatile in case you want to use it for a larger aircraft…

Up to 2,000 Pounds – 14 gauge rectangular 2x4” tubing Up to 5,000 Pounds – 11 gauge rectangular 2x6” tubing Over 5,000 Pounds – Consult a professional engineer

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The scissor lift is one of the most important pieces of the hydraulic lift seaplane trailer. A picture of a basic scissor lift design is below:

A basic table-top scissor lift. The scissor lift we’ll build for the hydraulic lift seaplane trailer will be very similar with one minor (but very important) modification. If you look closely at bottom rails that the rollers run on, you’ll notice that the rails are built with L shaped steel. This is the standard for almost all scissor lifts. The rails for your

trailer need to be built out of C shaped steel. Here’s why: The L shaped rails are designed to handle a load pushing down but not a load pulling up. With the L shaped rails, if the weight of the load on this scissor lift were to shift backward, the force on the front

supports would shift to an upwards force and the bottom rollers would pull right out of the track and the whole lift would tip backwards. Imagine that happening when your

aircraft is the load! The C shaped steel rails solve this problem by adding equal support for a down-force and an up-force.

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Here’s a narrow scissor lift designed for a 2,000 pound capacity trailer with a narrow wheelbase so it could handle small aircraft. This lift

was designed with a manual hydraulic bottle jack…

This scissor lift was designed for a 5,000 pound capacity trailer for larger aircraft like a Cessna 206 or Beaver. This lift was

designed with electric hydraulics…

You can access a full list of suppliers where you can get discounted manual and electric hydraulics for the scissor lift and one set of basic schematics on our website at http://www.SeaplaneTrailerSecrets.com/members/parts.html

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Close ups of the scissor lifts…

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Here’s a slightly cruder style of scissor lift…

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A rear view of a hydraulic lift trailer. This trailer was built by Marshall Gildermaster but it is very similar to our design. This design does not have

bump-stops, spreader bar locks, or adjustable width lift rails…

Front view of the same trailer as above. The adjustable width lift rails in our design place these lift rails closer to the floats, therefore putting less stress on the spreader bars. The wider stance also holds the aircraft more securely so it can’t slide sideways on the rails. The adjustable bump stops also ensure the center of gravity of the aircraft is balanced

correctly on the trailer to avoid a major catastrophe…

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Same trailer as above. We suggest that you park the trailer in place in the water and then pull the aircraft onto the trailer as opposed to backing the trailer under the aircraft, as shown here. One overzealous turn of your steering wheel could damage your floats…

Below is Marshall’s suggested trailer dimensions from his website…

SMALL SEAPLANE MOVER (ie: Aeronca, Cessna 170/172, Cub, Maule, Taylorcraft)

46" wide x 18" Tall - 2000# Max Weight

LARGE SEAPLANE MOVER (ie: Cessna 180, 185, 206, Beaver)

61" Wide x 20" Tall - 3500# Max Weight

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Here’s a couple of examples…

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Manual Lift

Seaplane Trailer

Advantages

1) Very cheap to buy or build. 2) No special mechanical/movable parts to break.

Disadvantages

1) You can’t easily get the aircraft off the trailer. 2) The length of the tongue makes it difficult to put in a

hangar and close the door.

You can also build a small, light-duty manual lift trailer without hydraulics or adjustable rails. The downside of this is that it’s

not easy to get the aircraft off of the trailer…

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Manual Dolly

Seaplane Trailer

Side view of a manual dolly seaplane trailer.

The next design for a seaplane trailer is the manual dolly. Let’s discuss some of the advantages and disadvantages of this design.

Advantages

1) Very cheap to buy or build. 2) No special mechanical/movable parts to break. 3) Low ground clearance design keeps the aircraft low. 4) Can be built as a break-down trailer that can fit in the back of an SUV or

mini-van.

Disadvantages

1) You can’t easily get the aircraft off the trailer. 2) Light-duty design will not work for heavy aircraft or towed takeoff.

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3) Aircraft weight is supported by the float keel, which can cause leaks.

The main advantage of the manual dolly is that it can be disassembled if you don’t have room to store your trailer at the airport. It does keep the aircraft low to the ground, which is an advantage over the flatbed trailer design discussed earlier. The disadvantages are that it’s designed for light aircraft only and it’s not safe for a towed takeoff. The manual dolly above was built by Robert Murray. Here’s his explanation of how it’s built:

“Take-down seaplane dolly for PA18 on EDO 2000's fits in back of large

mini-van.

Assembled frame is 10' x 4'. With wheel assembly, overall width approx. 11'- 6".

2 1/2" square steel tubing has 3/16th wall. Axle brackets are 1/4" thick.

2x6 wood platform is 40 x 48". Main wheels are approx. 22" x 5 1/4". Bolts

for frame and pins for tow bar 3/8th ss. 1/4" drain holes are drilled in

underside of frame and tongue.

Main wheels are 'doughnuts'(spare tires) from an auto junk yard. They are

mounted on solid axels - no bearings, which keeps maintenance to a minimum

but means you probably shouldn't use this dolly on roadways or for a towed

takeoff.

I had a boat-trailer front wheel (with crank) , but changed it in favor of

two fixed solid wheels. Tow bar (in 2 pieces) can go in front or inside

square tubing from behind to either push or pull the dolly. Length of tow

bar depends on slope of launching area and whether or not your vehicle can

go part way into the water. Removable wood platforms are made from pressure

treated material. Flags on fiberglass rods (purchased from a bike shop) help

to position floats over dolly when platform is submerged in the water.”

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Above is a picture of the manual dolly completely disassembled…

The manual dolly with removable wood platform…

Floats on the fully assembled manual dolly…

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The break-down manual aircraft dolly can transported in a minivan or SUV and quickly reassembled to pull your aircraft…

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Above are Robert Murray’s manual seaplane dolly drawings for a PA18…

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For larger aircraft (Beaver, Otter, etc.), you will need a lot wider and stronger trailer…

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Conclusion

In this Special Report, we exposed many of the unknown advantages and disadvantages of these different seaplane trailer designs. Many of these designs are very easy to build and designs like the versatile hydraulic lift trailer can be built for less than $2,000 in most cases. The ranking system (stars) that we attach to each design is based upon generalized advantages versus disadvantages. Pay close attention to both general use and structural concerns when deciding which trailer design is right for you. If you do decide to build your own trailer, take the time to have it properly engineered. The last thing you want to happen is to have your trailer break and watch your plane fall to the ground. We have a list of companies who sell pre-engineered plans for the flatbed trailer design on our website at http://www.SeaplaneTrailerSecrets.com/members/parts.html If you’re thinking of building the hydraulic lift trailer, you can base your design off of a pre-engineered boat trailer frame. We have a list of companies who sell pre-engineered plans for boat trailer frames on our website at http://www.SeaplaneTrailerSecrets.com/members/parts.html I hope this report has enlightened you to the many different seaplane trailer possibilities. Most people only know about one or two designs and end up building an inferior trailer. Each trailer is different and each has it place. We would love your feedback, testimonial and photos of your trailer. Please send them to [email protected] If you have any improvements or new designs not mentioned above, please send them to [email protected]

Happy Flying!

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Taking-Off From A Trailer Or Dolly

Taking-off from a trailer pulled by a vehicle or a dolly is possible and many FBOs and private pilots alike do it routinely. It does carry some element of risk no matter how experienced you are and it’s definitely not for the novice pilot. Below are quotes from pilots experienced in trailer/dolly take-offs. They share some of their experiences and some tips to help you complete a successful take-off:

“We made a "dolly" for a J-3 sized airplane, a few years ago, before I dug my 2000 foot pond (so I wouldn't have to take part in the "activities" anymore) - basically we made a triangular shaped frame with two wheels on the front and the tailwheel on the back - we actually used the wheels off the airplane - I put a piece of plywood on either side for the floats to sit on - we fastened it to the tube across the front and the diagonal tube that ran back to the tailwheel - with this fairly long space in between it's attach points, it sagged and sort of formed a cradle for the floats to sit in - we towed it out to the runway and pointed it down the runway - I tied about a 20 foot rope to the tail of the airplane and told a friend to run behind and keep the plane straight until we got enough speed for the air rudder to work - the only problem with this mater plan was that as I was barreling down the runway - the J-3 didn't seem to be accelerating - all of sudden it just leaped into the air - I turned and looked back as the dolly spun off the side of the runway and my steering man lay almost passed out with exhaustion just behind the dolly - I told him to keep the airplane straight (which he did a fabulous job!!) but I never told him to let go - he ran at about 20 MPH for about 500 feet down the runway!! This worked well but a J-3 is light and gets off good. Some friends of mine took a Utva 66 (Yugoslavian military airplane about the size of a 185) on floats off a large flatbed trailer behind a truck going down the runway - it worked for them. I have heard of someone wrecking a 185 on floats doing the truck and trailer routine some where in Michigan. There was also a story about Dehavilland, when they used to take the Beavers and Otter out of their Toronto factory years ago - they had a fancy dolly that when the airplane lifted off, brakes came on - on one particular day the brakes didn't work and the dolly went across the tarmac and totaled one of the executives new Cadillacs.” - Doug Ronan

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“The only major problems we had with dolly take-offs was similar to what Doug R. described. When you used a large dolly we found that the low HP aircraft 50 to 90hp had trouble bring the dolly up to take-off speed. For these type of aircraft we would require at least 3000ft of runway.” - J.J. Frey

Avoid cross winds. Forward stick helps or nail a wooden cleat behind the step. Feed in power gradually as truck accelerates. I have the truck driver call out ground speeds on a handheld. I don't ever remember hearing "fifty miles an hour" for my PA18. I was gone by then. Be sure to leave the driver enough room to slow down before end of runway, but not before you are airborne. If you are operating from a short runway, it might be useful to have truck do a dry run to see where you reach fifty miles an hour and set up a traffic cone or other marker at that point. All in all it's easier than you probably imagine. A gentle tug on the stick will get you unstuck from the trailer/dolly, then make a shallow climb out. By dry run I mean without the aircraft on the trailer. When you're doing this for the first time, one of the concerns for both pilot and driver is to know approximately when or where to expect lift off. Following which the driver have to worry about stopping (if it's a short runway) and the pilot about climb out. Having the driver call out truck speeds on a hand held from about 35 - 40 mph on will give you an idea how you are doing until the airspeed indicator kicks in, but it's not something I would bother with if you have plenty of runway. The purpose of the wooden cleat behind the skeg is to prevent the a/c from sliding backward and to reduce any tendency for it to walk around on the trailer as you reach flying speed. Do a thorough run-up check but don't come in with full power too early into the run. Let the truck get you up to speed. Forward stick also keeps the a/c in place until you have reached lift off speed. I've seen trailers with very short tongues used for this purpose. The a/c tends to rise into the air as the truck pulls ahead without much danger of the floats hitting the truck. If you are not in radio communication a second person in the truck can let the driver know when you are clear. Make sure you have enough airspeed to prevent settling. ie don't stall it off. As I said, you likely will be surprised how easy it is. It must be. I've done it. - Rob Murray

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I took off from a flat trailer in a J-3. I hooked the plane to the trailer with a military seat belt hooked to lines between the floats. the seatbelt had a string for a release to the cockpit secured by masking tape. The purpose of this, is in case of an abort, a gust, or the application of too much power, the plane will stay with the trailer This sounds complicated, but it isn't. I used a weak string held by masking tape so it wouldn't interfere with the flight if it got stuck. The trailer had a long tongue that would flex some. The car was a 4 banger and it was a grass strip. I found that as the car accelerates I could flex the trailer tongue with stick pressure and I could help the acceleration with the throttle. I added power slowly to help the acceleration and flew the plane to keep the tongue straight. It didn't take much runway, when I saw 40 on the airspeed indicator, I knew I could fly, I pulled and released the string to release the seatbelt, lifted off and turned right to avoid the car. It was not a difficult bit of flying, but I had to be prepared. You have to be sure that however you attach the plane to the trailer, that it won't get hooked to the trailer when it is time to fly. The release has to be fool proof. If you don't want touse that method, you need to build a cradle for the floats to rest in so they won't slip to the side or for and aft. Be careful and good luck - Jim Poel

Make sure that the aircraft, when on the trailer attached to the vehicle, does not have a positive angle of attack. You could get blown backwards off the trailer before reaching take off speed. Make sure that the aircraft is positioned so that the CG is over the wheels and tongue weight is not excessive. A big change in trailer deck angle on departure is not a good thing. Use a smooth runway. Do not use a trailer that has light springs. You do not want to get bounced off below flying speed. If you have never done this before find a pilot who has and get him to do it. Watch and learn and then do it the next season yourself. - Doug

For online videos of seaplanes taking-off from trailers and dollies, visit our website at http://www.SeaplaneTrailerSecrets.com/members/video.html

aircraft trailer secrets › members › seaplanetrailer... · 2019-10-30 · under the aircraft...

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