Issue 19

Article By Greg Covey

Print Issue 19 "Float Flying"

Flying an R/C plane off water can be one of

the best experiences you can enjoy in our

hobby. When done correctly, the site of your

plane gliding across the water is both

mesmerizing and a great deal of fun!

If you live in a northern climate, the floats

can also be used to fly off snow. Further,

when enough power is available, a float plane

can even take off from grass.

In this month's issue of AMP'D, we'll cover

some of the key points in adding floats to any

plane as well as some tips on successful

flying off water, snow, and even grass!

Multiplex Mentor

The Multiplex Mentor is a replacement for the Magister and is a

robust trainer and tug (tow plane) made of ELAPOR (pronounced

el-a-pore) foam. Medium CA glue used with an activator (or kicker)

as the only method of gluing recommended by the manufacturer.

This radio controlled model is electric powered and Almost-Ready-

to-Fly (ARF). It is meant for beginners to intermediate fliers.

Trainers have been around since the very beginning of model flying.

The so-called .40-size trainer was offered in a multitude of

variations all over the world. The beginner is expected to

cope from the outset with an easily damaged all-wood model and a motor which is not properly set up or even broken

in. It was no surprise that this type of "first model" was often the modeler's last.

The Multiplex Mentor was designed with the beginner in mind. The ELAPOR foam provides a robust, high-strength

structure that is easily and quickly assembled using CA glue. The aircraft's flying characteristics are simply

outstanding! When using the mating Multiplex Brushless Motor Power Pack (M993228), which contains a motor,

ESC, Prop, and hardware, the trainer provides reliable, maintenance-free power flight after flight.

Schwimmer-Bausatz for Mentor

A whole new level of fun was created for this model by using the Mentor Float Set (or Schwimmer-Bausatz) from

Multiplex. The solid Elapor floats come with custom bent aluminum undercarriage supports, water rudder, and all the

hardware. The 5-language manual has detailed text and drawings to make the assembly quick and easy.

After first drilling 1.5mm holes in the plastic bars,

they are glued into the mating float slots. I used CA

on the float foam, sprayed the plastic with kicker,

and then simply pressed them in place.

The undercarriage supports are then mounted to the

floats using the supplied screws. Both aluminum

supports angle toward the float center.

The existing ground gear undercarriage is unscrewed and the new float front undercarriage fits right in its place. You

can then mark the exact spot to cut a 6mm deep flat area for the new rear undercarriage. I used a hobby saw and then

lightly sanded the area flat.

The plastic plate is CA'ed in place and the new float assembly is secured by the four original machine screws up front

and four new sheet metal screws in back. I needed to open the holes slightly larger in the back brace to allow the sheet

metal screws to freely fit through the holes before being secured into the plastic plate.

The next step is to attach the water rudder. On smaller planes, I sometimes skip this step and see if the rudder has

sufficient authority to turn the plane in water at low speed. However, Multiplex states that the water rudder on the

Mentor is absolutely essential for both steering in water and flying. The additional area of the water rudder is needed

to aid the normal rudder in controlling the larger lateral area distribution. The water rudder also works in snow!

The water rudder is made by copying the full size diagram in the manual and then simply replacing the steerable

tailwheel. The tail assembly piece must be drilled out to 2mm to accept the larger metal rod used by the water rudder.

I used shipping tape to secure the foam rudder to the bent rod.

I made a few simple modifications to help keep the

ESC safe from water damage. I first sealed the ESC

ends with some Zap-A-Dap-A-Goo II which helps

keep the water out.

I then cut a piece of nylon screen material from an

old furnace filter and glued it over the air intake

opening using more of the Zap-A-Dap-A-Goo II.

This protects the opening from water splashing

inside while allowing most of the air flow to

continue cooling the motor, ESC, and battery.

When finished, the CG was in the same spot as

before I started and the float step was right under

the CG. Now that's German engineering!

Float Flying in the Finger Lakes

The Finger Lakes are a pattern of lakes in the west-central section of Upstate New

York. The lakes are linear in shape, each lake oriented on a north-south axis. The

largest lakes in the group collectively reminded early map-makers of the fingers of a

hand.

One of our local club events, sponsored by the Canandaigua Sky Chiefs, is held at

beautiful Honeoye Lake in the Finger Lake Region.

Honeoye Float Fly Introduction Video (16 meg)

In the video below, my friend Lynn Bowerman and I, took turns with the sticks and had some aerobatic fun with the

Mentor. This model flies very well for 10-15 minutes on only a 3-cell LiPo pack.

Multiplex Mentor on floats Video (27 meg)

The Monocoupe on Floats

Back in 2003, I did a review of the Bohemia Models Monocoupe for Hobby

Lobby. This 7’, 10lb giant scale plane was a blast to fly during the summer.

The giant scale Bohemia Models Monocoupe has an 82” wingspan and weighs

about 10lbs when converted to electric power. For all its intimidating size, the

1920s Velie Monocoupe model was a relaxing docile flyer.

I missed flying the model during the long winter months in upstate NY so I decided

to add some floats the following year and have some fun in the snow! By adding a

set of 35” “Zeedoo” fiberglass floats, I was now able to fly it all year off of snow

and water.

A general rule of thumb is to use floats that are about 75% to 80% the length of the

fuselage. The pre-fabricated “Zeedoo” fiberglass floats from Hobby Lobby came in

various sizes and the largest 39” set provided about a 74% ratio which was just

about perfect.

Although the floats added about 1.5lbs more to my flying weight, the stock Monocoupe wheels were also removed to

drop the weight by 11oz. My net weight gain was about ¾ lb.

The Zeedoo floats were very strong and easy to install. I used the stock Monocoupe gear axle for the front struts and

hand-made a rear strut from K&S 0.156 (5/32) music wire. The rear strut was then attached to the solid brace just

behind the cockpit area and reinforced internally. I used Dubro (#158) Steel Landing Gear Straps to attach the music

wire to the fuselage.

Everything worked very well and we had a blast flying the big model off a snow-covered field. It was fun to get

outside in the wintertime and enjoy a sunny day while dreaming of warmer weather. After the flight was over, I

realized that my floats were not very parallel so I removed one of the front spacers on each side to make them perfect.

Although not needed for snow take-offs, a water-rudder is needed for taking off the water. I selected two of the Ernst

(#156) Retractable Float Rudders for .90-1/4 Scale from Tower Hobbies. I decided to use two water rudders controlled

by flexible cables from Great Planes (GPMQ3702).

My Monocoupe on floats was a good success at a 2004 float fly in the finger lakes of upstate NY. Although take-offs

were a bit weak, we flew the Monocoupe five times during the day.

Once airborne, the plane still flew at half throttle but initially breaking the suction of the water contact required some

skill and long take-offs. After upgrading the power system to an AXI 4130/16 and a 6s LiPo pack, the Monocoupe

was stored in my garage loft for 6 years.

Return of the Monocoupe

Flash forward to September 2010 and my old

Monocoupe was pulled down from the loft and

made ready to return to Honeoye Lake.

After testing all the control surfaces, my only real

change was to upgrade the cylinder heads on my

mock Velie engine and change out the old NiMH

packs for newer Lithium technology.

The original power system for my 2003 review used an AXI 4120/14 with a 14-cell, 2600mAh NiMH pack and APC

13x8 e-prop. I measured 8200 RPMs at 43amps but had no wattage readings. Although never tested, I had upgraded

the power system to use an AXI 4130/16, APC 15x8 prop, with two of the ThunderPower 3s2p, 4200mAh packs in

series. The short ThunderPower packs fit well just inside the nose. The power system drew about 50amps for 1000

watts of power. The extra weight in the short nose helped with the balance and I was certain that the increased power

would provide water take-offs in any conditions.

In the video below, Lynn took the sticks and showed just how well the new power system worked when flying off

water. The model flies for about 10-12 minutes on a 6-cell 4AH LiPo pack.

The Monocoupe on floats Video (20 meg)

E-flite J3 Cub on Floats

In 2006, I reviewed the E-flite J3 Cub 25 when it was first released. The review

included the original build with wheels and the optional adaptation to the 25-Size

Fiberglass ARF Floats (EFLA500). Four years later, the E-flite J3 Cub 25

(EFL4000) is still being sold, which speaks for its scale appearance and

performance.

The solidly-built model is the only 25-size Cub with scale ailerons. Quality balsa

and light plywood construction make for a sturdy, lightweight airframe that handles

incredibly well in most flying situations. The firewall is set up for use with an

outrunner motor, such as E-flite’s Power 25, making a perfect power match for the

airframe. The optional floats add a new dimension to the scale flying experience,

and the one-piece wing allows for easy transportation to and from virtually any

flying field, pond or lake.

I have found that the E-flite J3 Cub when equipped with floats takes off well from

water, snow, and even grass! It is a versatile all-seasons scale flyer.

The float kit provides a ventral fin for adding stability in

flight, especially at slower speeds.

When taking off grass, the floats can be made extra slippery

by spraying Pledge furniture polish on the bottom. While it

is not always needed, keeping a can of Pledge in your flight

box can come in handy when the grass is long and green.

E-flite J3 Cub 25 on floats Video (xx meg)

ParkZone Meets HobbyZone

Since I fly off grass, snow, and water, these

HobbyZone Super Cub floats (HBZ7390) seemed

like a good experiment to try on my ParkZone

Extra 300 (PKZ5180).

When landing the Extra 300 in the thick grass, I

would sometimes rip off the gear mains. Although

it was an easy CA repair, I had other planes on

floats that are fun to fly off grass so it seemed

natural to me...but probably not scale.

When tested, my Extra 300 continued to perform

well on the HobbyZone Super Cub floats. It

retained all its aerobatic capability while allowing

me to take off from grass, water, or snow.

The only trick to mounting the floats is to make them parallel with the plane body so

you need to keep the front metal bars flush with the fuselage bottom. I did this by

gluing some plywood pieces in the existing grooves where the normal gear mains

mounted. You can then hold the front frame in place either by wedging a center

plywood piece in the middle or gluing it in place.

For the back frame, simply cut out a rectangular piece in the foam so that the

additional plastic piece that comes with the HobbyZone floats mounts flush.

The video below is of my stock ParkZone Extra 300 on the HobbyZone Super Cub floats. As you can see, it has

retained all of its aerobatic capability but the floats allow me to take-off and land on grass without tearing out the

mains.

ParkZone Extra 300 on HobbyZone floats Video (12 meg)

Float Tips

Although there are some things to keep in mind when flying off water, float flying

is very similar to flying off land. The length of the floats should be around 3/4 of

the fuselage length measured from the prop to the rudder hinge.

The 30" fiberglass floats on the left are sold by Hobby Lobby (HC1802) for 5lb to

7lb planes. They are similar to the ones I used on my Monocoupe, only smaller in

size. Fiberglass floats have an advantage over plastic molded

floats because the corners are molded much sharper, which makes them plane on the water much better than the

rounder-shaped plastic floats.

The step of the float should be located on the CG or just behind the CG. As the plane starts to increase speed on take-

off, the floats ride up onto the step and reduce most of the of suction from the water surface.

A ventral fin, like the one supplied in the E-flite 25-Size Fiberglass ARF Floats (EFLA500), will increase the effect of

the tail feathers and keep the plane going in a straight line.

For completes details on float selection and setup, read "THE BASICS OF FLOAT FLYING" by Ironsides and Jim

Casey's "RC Seaplane Webpage".

Summary

The wind picked up in the afternoon so we decided not to fly the smaller planes like

the Clever Boy from Maxford USA and the Polaris from ModelAero. You can see a

video of the Clever Boy on floats from my 2007 review on RCU. Both of these

planes can take off from almost any surface. They are versatile and fun to fly!

One of the key points when adding floats to any plane is that it is not just for flying

off water. If you live in a northern climate, the floats can also be used to fly off

snow. Further, when enough power is available, a float plane can even take off from

grass. If the grass conditions are "sticky", the floats can be made extra slippery by

spraying Pledge furniture polish on the bottom.

Although the size of the floats doesn't have to be perfect, a general rule of thumb is

to use floats that are about 75% to 80% the length of the fuselage. When flying off

water, adding a water rudder and ventral fin help control the plane in the lake and in

the air, respectively.

When you fly electric, fly clean, fly quiet, and fly safe!

Special thanks for contributions by:

"Papa Jeff" Ring, Lynn Bowerman, and Devin McGrath

This section of AMP'D covers some of the questions that our readers have sent in and I thought would be interesting

for others.

John W. asks:

Greg,

I read with interest your review of the T-34 Mentor by E-flite. I have one

and it performs great except that the canopy/hatch would fly off during

flight. At first I thought the magnets were not engaged but after ensuring

the magnets were ok it flew off again. You can imagine what losing the

hatch does to the flight characteristics!

Several others have had the same problem. Horizon did not acknowledge

that there was a problem, but they did send me another canopy/hatch

that unfortunately did not fit (too long). I have patched the original

canopy with R-560 and I am securing the hatch with tape to keep it

intact. Of course this has to be removed to change batteries. This is not a

big deal but I am trying to find the real cause to the mastery of the

"flying canopy".

Any feedback on this problem and solutions? Any ideas on what might

be the cause? I have a suspicion that it may be air pressure pushing the

canopy/hatch loose. Your thoughts would be appreciated.

Hi John,

I agree that the Mentor has a big canopy that you don't want to lose in flight.

It is certainly possible for air flow to come in from the cowl front and build

pressure inside the fuselage. This air flow is designed to cool the components

inside. The question is there sufficient pressure to pop off the canopy in

flight? One way to reduce the pressure is to make the air exit opening about 3

times the size of the air intake opening. There is some covering on the aft end

of the fuselage bottom that you could cut away to allow more air to

exit…thus reduce pressure

Another possibility is that the fuselage twists in flight and weakens the hold

of the magnets. A combination of twisting and air pressure is yet another

possibility. My canopy seemed to hold on well until we really beat on the

plane during aerobatics. A few small pieces of tape worked nicely to hold it

in place.

Good luck with your T-34 Mentor!

Ask questions by e-mailing me at greg@rcuniverse.com

Hobbico LiFe Source Receiver Packs

Xoar Beechwood Props

Spektrum AR6400LBL DSM2 6Ch Ultra Micro Receiver

with Brushless ESC

RC Lander Metal Retracts with Suspension Struts

Print Issue 19 "Float Flying"