Spitfire76's Build log of FT's Simple Cub (to fly off water)

[Spitfire76]

This summer has been the first time that I've flown off water and I've really enjoyed it. With temperatures these last 2 months almost constantly being 100F + it has been so much more pleasant flying off of a local lake than at my AMA club field.

The first foam board plane that I built for the water was the FT Sea Duck. I really loved this plane but last week I did have to scrap it after a bad crash onto the shoreline. Here is the log.

Spitfire76's Build log of FT's Sea Duck (to fly off water)

Note: This is more of a post build log as I have completed the Sea Duck but have yet to maiden it. The reason for building the FT Sea Duck Several members of my AMA club fly at a local lake during the summer and since I have never flown off water I wanted to give it a try. Initially I thought...

forum.flitetest.com

I also added floats to my FT Tutor but after installing a Spektrum flight controller from an E-flite Apprentice it also crashed. So I am now turning to the FT Simple Cub as its a fast and simple build.

 

[Spitfire76]

My friend gave me a fuselage and some floats that he had built so I just need to add the power pod and wings. Not counting floats there are only 11 parts to this plane.

 

[Spitfire76]

What motor should I use for the Simple Cub ? The FT store has 2 options a B pack or C pack radial and so since I have the C pack radial from the Tutor that I crashed the other day I'll use that. It should give me plenty of power to get off the water.

FT Simple Cub MKR2

The FT Simple Cub is easy to build and easy to fly. 11 separate pieces of foam is all that is required to build this RC plane.

store.flitetest.com

I'll also go with 3s 1300mAh batteries as I have a few of those.

 

[Foamforce]

I would definitely do the C pack. When I flew off the snow with a Tutor with those floats and a C pack equivalent, it was already somewhat of a dog, so I can’t imagine it would have gone well with a B pack.

 

[Spitfire76]

Floats painted to help seal them.

 

[Spitfire76]

Notes on the build.

• Cut off tabs on power pod as they are not used and make it a tight fit.
• Wing servo arm hole- as per build video, nearest center to provide minimum throw (ailerons are large).
• Elevator servo arm hole - middle as need reasonable throws for getting off the water.
• Rudder servo arm hole - nearest center seems to provide sufficient throw.
• Covered in some holes on the bottom of the fuselage to keep the water out but may reduce the ventilation.

 

[Spitfire76]

Elevator and rudder servos installed. Elevator servo is on the right.

 

[Spitfire76]

Power pod layout


Note the battery or ESC is not going underneath as it will get wet.

I plan on using a Gemfan 9x6 prop on the C radial motor.

 

[Foamforce]

Note the battery is not going underneath as it will get wet.

Are you going to copy the hood from the Tutor?

 

[Spitfire76]

Are you going to copy the hood from the Tutor?

I was considering that but initially I'll just pull the power pod out a bit to install the battery.

 

[Spitfire76]

The Cub is finished and I am off to the lake in the morning to maiden it.

I had forgotten how simple and quick this plane is to build.

 

[Spitfire76]

Well the maiden did not happen. My friend tried to fly his cub first but it would not get off the water and he could not steer it very well. Also there was a bit of a breeze and then it tipped over. I sent out my rescue boat but by this time his plane was a long way out. Also the rescue boat didn't seem to be performing as normal and eventually I lost control of the boat. We found a paddle boarder that recovered both the boat and plane. The boat had one motor dangling by its wires and off its mount and the other motor was missing. Maybe the screws came loose but not sure. Anyway boat is being repaired and I will try to maiden the Cub this Friday.

 

[FoamyDM]

Well the maiden did not happen. My friend tried to fly his cub first but it would not get off the water and he could not steer it very well. Also there was a bit of a breeze and then it tipped over. I sent out my rescue boat but by this time his plane was a long way out. Also the rescue boat didn't seem to be performing as normal and eventually I lost control of the boat. We found a paddle boarder that recovered both the boat and plane. The boat had one motor dangling by its wires and off its mount and the other motor was missing. Maybe the screws came loose but not sure. Anyway boat is being repaired and I will try to maiden the Cub this Friday.

Good Luck Sir

 

[Spitfire76]

The maiden was successful but I stalled the plane on my second flight. Normally I would have used my recovery boat but a nearby woman offered to swim out to get it. There was a but of a breeze and the plane was much further out by the time she had reached it and I was getting worried that she was getting tired. I don't know how she made it back holding the plane in one hand and swimming with the other. The plane suffered no damage and the electronics just need to dry out.

 

[Foamforce]

How was takeoff? Adequate power? How about air handling?

 

[Spitfire76]

How was takeoff? Adequate power? How about air handling?

With the radial C motor and a 9x6 prop it seemed to have plenty of power to get off the water.

On the first flight I lacked aileron authorly so I moved the control rod to the middle hole on the servo arm.

I just bench tested the electronics and none seemed to be damaged by getting wet although I need to secure the Aura mount as the paper under it did come away from the foam.

 

[Spitfire76]

So took the Cub back to the lake this week and flew it a total of 4 times. This is one of the flights.

Just to note the control rods for the Ailerons are now in the center hole of the servo arm.

 

[Spitfire76]

Ideas for design improvements.

The 3d printed mounts for the rudder and elevator need to be mechanically secured to the foam rather than just hot gluing them to the paper as the paper will delaminate when wet.

 

[bisco]

that was beautiful, what a sweet flyer. well done!

 

[Spitfire76]

This Cub is really flying well off the water and I must have had around 10 flights from it so far. I noticed though a bit of a gap developing just under the wing. It looks like the foam board between the 2 ailerons needs some strengthening.




I flew it at the lake yesterday and although the first flight was great, including the landing I hit the water rather hard on the second and the front float mount collapsed. I still had power but could not steer it to the shore so got out the recovery boat. Videos to follow.