Full Lotus, Full Lotus Floats, Full Lotus amphibious floats, troubleshooting the Full Lotus float system, flying on Full Lotus floats.

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Rating the Full Lotus float systems

The Full Lotus float system has been on the market since the mid 1980's. They were designed to be light and rugged, and over the years have become one of the best selling float systems on the market.

The Full Lotus system came about because anything being built for ultralights at the time was being done by small under funded back yard operations, building floats by using the "R&D" method. With R&D standing for "rip off and duplicate." They learned they were doing something wrong when you called to complain that it didn't work or broke.

Full Lotus on the other hand had the finances to design and develop and test a float system, from the ground up using technology that was not available to the "R&D" group. This system was the number 1 float system for ultralights at the time.

The following is based on knowledge from over 5,000 hours of float flying on 158 different float and amphibious ultralight style aircraft. Plus personal installation, test flying and adjustment of floats on 145 ultralight category aircraft since 1978.

Common Full Lotus problems

UV - The Full Lotus float mounting area is made from materials that degrade over time with exposure to sunlight. For this reason Full Lotus uses two layers of material on the top of their float in the float tube mount area.
(Note: very early models of the Full Float only used 1 layer.)

The first layer is exposed to the UV and is sacrificed to protect the second layer. Pilot's who have floats with a damaged outer layer, or a layer that has been removed for whatever reason should inspect this area of their floats regularly. Remember this is the area that connects your plane to the float. It is being subjected to extreme speed, and pressures during take off and landing.

Inspection of the threads holding the mounting material onto to the top of the float should also be an area of inspection for UV damage.

Bladders - When flying on Full Lotus floats there are a number of things that you should have near by.
  • Pressure gauge for checking air pressure in each bladder of the float prior to each flight
  • Air pig or pump for refilling bladders
  • Spare bladders for both front and rear of float
  • Make sure to fly with a bladder repair kit in your tool kit.

It is important the Full Lotus float system be checked for proper inflation before each flight. Under inflation of the bladders can cause the bladder to move inside the float, which will eventually cause it to leak. Over inflation can lead to a bladder exploding on landing causing loss of floatation.

Bladders should also be removed several times a season and checked for water. The bladders will collect water from osmosis, and condensation. Several pilot have reported accumulations of over a gallon of water in their bladders!

Remember this water is able to MOVE. During lift off it will move to the REAR of the float. This can cause loss of control due to improper C of G. Unlike regular floats which can be pumped out the only way of removing the water the Full Lotus system is to remove the bladders.

One pilot flying his craft on floats in winter reported over 40 lbs of water had frozen into ice in the rear of his floats!

Zippers - Several years ago Full Lotus updated the way that the top and bottom sections of their floats were held together. The older system used plastic zippers to join the two halves together.

There were apparently reports of failure of this system. In November of 1998 Full Lotus issued a "CEASE FLYING" directive for their float system. It basically said to stop flying on the float until a FREE at the time update was installed.

This is the newer style of system.

Step Area - The step area of the Full Lotus float has been modified several times. The first modification replaced the wood material used at the step for support with metal. It was found that the wood rotted with time and exposure to water.

The second modification was the addition of a set of small bladders located in the step area of the float. Pilot's of heavier ultralight aircraft with double surfaced wings were reporting problems getting airborne.

The problem was traced to the float support tubes bending when the pilot rotated for lift off. This allowed the front of the float to move up but kept the back of the float on the water preventing lift off.

The bladder system stiffens up the float in the middle. Experience has shown that while this helps, it also suggested that thicker walled tubing be used for float support. The recommended tubing even with sleeves is just not rigid enough when used on heavier ultralight aircraft requiring 40 to 50 mph to lift off.

Spray - Full Lotus floats are very wide and the spray coming off of them is considerable. This spray can enter the prop area in a pusher configuration, which will cause loss of thrust, and could result in prop failure.

Many manufacturers and owners of trikes, and other pusher aircraft are now installing splash rails on the side of the floats to help prevent this. In the case of trikes a splash pan such as shown here can be installed.

The other problem area is the tail section, of craft that are mounted low on Full Lotus floats, with the tail section directly to the side or behind the float. For demonstration purposes picture a spray of water 2 feet wide coming off the floats and hitting the tail section at 45 mph.

It is recommended that any water coming off the floats be prevented from striking flight controls such as the horizontal stabilizer, rudder, and elevator.

How to mount the Full Lotus float system on your ultralight aircraft.
Many owners of Beaver's, Quicksilver Challengers, L'il Hustler's, Merlin's, etc. use their original landing gear with some minor modifications.

This requires a lot of fabrication of parts, and drilling of tubing that has to be re-drilled if the floats are not mounted correctly the first time.


Here Full Lotus floats are mounted on an MX style ultralight.
A simpler installation is to use the original landing gear when possible and install square tubing below it. Then use U bolts to connect your landing gear to the round tubes used on the Full Lotus system.

Using this system no holes need to be drilled into the float tubing or fabric AND the floats can be moved fore and aft by just venting air from the float and then refilling them in the required position.

Here Full Lotus floats are mounted on a Hornet, using square tubing and U bolts for a very clean and simple installation.
Drag - Pilot's report lower climb rates when flying on Full Lotus floats versus aluminum, fiberglass, composite or wood floats.

They also report needing higher rpm settings to fly at the same speed on Full Lotus floats versus more the more aerodynamic shaped fiberglass and aluminum floats.

On two identically powered and propped Challenger aircraft one flying on Full Lotus floats the other on Puddle Jumper floats the climb rate for the Full Lotus equipped craft was 25% less, and the cruise rpm had to be increased to 6400 from 5800 to maintain the same airspeed.

The other problem is that most Challenger float installations make use of the landing gear to mount the floats. This puts the tail section directly in the path of the spray coming of the floats. Which decreases take off performance and can lead to structural damage to tail supports, and control systems.

Two systems that work considerably better on the Challenger are the Puddle Jumper float, and the Key West Float system, with my preference being for the Key West.

Specific Full Lotus aircraft installation problems.

In all of the cases above we have talked about pusher aircraft. Now lets look at aircraft in a tractor configuration.

A number of problems have been reported when using Full Lotus  1200 or 1260 floats on craft such as the Merlin, Rans Courier, Rans Coyote, Kitfox, Avid, L'il Buzzard and L'il Hustler.

The reported problems are

  • the submersing of the front of the floats when taxiing, especially right after the throttle has been backed down
  • the submersing of the front of the float while taxing in rough water
  • being able to get on the step and take off with one pilot but NOT being able to get on the step when two pilots are on board

These problems can be traced to floatation. In my opinion the 1260 floats do not have enough floatation in the front section of the float for most two place, tractor aircraft.

In most pusher configuration aircraft the weight put on the craft is distributed over the full length of the float. In the case of the Challenger front pilot is supported on the front section of the float, the pilot sits on the step or middle section and the fuel and motor sit on the rear section.

In the case of MX the pilot(s) sit in the step area, the motor and reduction on the rear section and the fuel on the nose section.

On a tractor aircraft the full weight of the engine sits on the front section, with two pilots and full fuel normally located near or on the middle area of the float.

In the case of tractor engine, tandem seating craft the weight is spread out more evenly but still ONLY towards the front of the plane. This is why the craft becomes a submarine on the front end when you taxi in rough water, or back the power down quickly.

When pilots adjust the float forward for more floatation they can't get off the water because the step is in the wrong location. The plane just plows through the water nose high a lot like a boat with too much weight in the rear.

Trike aircraft present also have problems with the Full Lotus Float system.

Trikes do not have a tail with a control system to help force the float up on to the step.
Trikes center of lift changes as the control bar is is moved forward and aft.

A system that was designed from the ground up to work on Trike aircraft is that designed by Krucker Manufacturing of Sudbury Ontario. The Krucker system is very aerodynamic and has two steps. These steps are specifically positioned on the float to work with trikes.

As the trike picks up speed the second step helps force the front step out and the floats out of the water. The system is extremely light, durable, easy to mount and can be equipped with a very light weight, quick and efficient amphibious float set up.

Krucker also has a variety of accessories specific for trike application. These guy just don't build trike specific parts - they fly TRIKES so they know what is needed.
For more information:

Krucker Manufacturing Ltd.
1400 Barrydowne Road,
NORCAT Building,
Sudbury, ON, Canada.
P3A 3V8
Phone: (705)521-8324 Ext.217
: (705)521-1040
e-mail jp@4kru.com

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