Sea Viggen

[RavenFly]

I have been looking at my Viggen and thinking converting it to a Sea Viggen would be fun.

I intend to graft on a cub float and some cut foam skids for the delta wing tips and see if it will work. I am flying 4s 2300 mah with an 8-blade 70mm fan (2845 3000kv).

Will have to figure out a water rudder and also plan to add a CF spar to the single sheet wing to help with durability and stiffening up the wing as it has warped on my original viggen.

I haven't been able to find anyone who has tried, this. Let me know if you have or have any advice as I start kit-bashing this.

 

[LitterBug]

I fly above seas of corn, wheat, and beans. Haven't found floats that work on those. You could use thrust vectoring for yaw control. Perhaps just a rudder in the EDF exhaust....

I need to finish my Viggen. I tried to add a spar where the wing fold was in the speed build kit, but between the spar and wiring for wingtip lights, I botched up the kit wing. Still need to cut a new wing in order to finish mine out.

 

[RavenFly]

I fly above seas of corn, wheat, and beans. Haven't found floats that work on those. You could use thrust vectoring for yaw control. Perhaps just a rudder in the EDF exhaust....

I need to finish my Viggen. I tried to add a spar where the wing fold was in the speed build kit, but between the spar and wiring for wingtip lights, I botched up the kit wing. Still need to cut a new wing in order to finish mine out.

I think I will go with a water rudder. I’m ok with bank and yank in the air, but want the water rudder for more “bite”. TBD.

Plan is to see how deep it sits fully loaded on the cub float and see if I need a bigger float to keep air under the wings when in the water.

 

[RavenFly]

Ok, test 1 took me a while to get to with other priorities, crashes and fixes.

Here is what I did for v1: I glued the Cub float into approximately the right place for the CG and water step location.

Then, I mocked up a water and thrust rudder using a piece of a fishing tackle tray and control horns as a pivot point. I hacked a spot for a rudder servo and cut into the fuselage to attempt to seal up my ESC in case of water penetration. Some floor insulation float tips behind the leading edge are not shown.

Result: Not enough buoyancy on water taxi test with my batteries. While the rudder and thrust paddle were effective, the wing tips kept digging into the water.

For the hell of it, I decided to hand launch just to see how it flew with the float attached.... and my CG was off. Barely crash-landed on the belly. Moved the battery forward, ripped off the rudder servo and rudder mess, and had another go, realizing that the thrust tube I had used in the original build was paper and sagging after getting wet. Oh well. Point proved, it flew and I caught it on the dock rather than try out the float on the water again.

V2 plans - going to kitbash:
- a larger float I have from a Turbo Timber and see if that gives more buoyancy.
- I'll use its built-in rudder with a servo mounted on the belly of the viggen way closer to CG and remove the thrust vector paddle. As long as I have a rudder on the water, I can bank and yank in flight.
- FT's v2 wing for more lift and stiffer wing. My Viggen had a real bow in it and was ready to be rebuilt anyway.
- extend the float tips forward of the wing. May use the float design from the Sea Duck instead of the XPS foam.

Will get a video of it next time.

 

[L Edge]

2 concerns I would worry about:

If the float step isn't at the right position, might have a problem in taking off. Not enough power.
I have a 4S 12 bladed balanced 70mm EDF and I added a thrust vectoring nozzle, goes nicely, but lacks power to do any fancy acrobatics.
You might need a 80 mm to make it work.

 

[Piotrsko]

Could rock it with a bit of elevator to break suction. Tips typically dont have water contact, might require a 1/2"spacer under float.

 

[RavenFly]

It did seem like it had enough power to take off, but the tips were digging in so I never got that far. Once I hand launched, I didtn have CG right and it crashed..

I just tacked on the floats from the Sea Duck ahead of the wings to get better coverage. I will try another float/taxi test in the next day or two.

 

[RavenFly]

Update. Float repositioned and mounted stiffer to underside of the wing. MUCH better water taxi performance and able to get it up on step. Just for the heck of it, I held full back and managed to get it to take off, even with the damaged wing.

Next step - rebuild with the new V2 wing and care to build lighter. One option would be to use the new floats that FT released for the Twin Otter.

I am getting the feeling it would be easier to just hand launch it and then catch on the dock rather than add all this weight..