Savoia Marchetti S55X (round two a never ending story)

[bweaver]

Bruce,
I am impressed! Beginning to think of you as Mr Warwing, but for me, this is way better! I missed what happened to the first S55X (such a cool airplane!) ....or is that a closed topic?
Anyway, well done!
BTW,  In order to lend a Canadian flavour to your build, I could bring a Canadian beer can to the next pilots' meeting to replace the A&W thing...do you need a regular size, or tall boy?
Cheers,

Bill

Hi Bill, 

The original balsa model cruised a number of times and flew once.  When flying, it made a number of circuits at the Indian Line Campground reservoir.  It needed a lot of up elevator trim to get it to fly without wanting to dive, but on a slow turn it tip stalled and spun into the water. That's where it met the bottom of the muddy reservoir.  Minor damage, but I have yet to fly it again.  I have felt that it would fly better if it was larger.  (Hence, my current project.)  The original still sits pretty on display in my home.

Regarding your offer for the beer can(s).  Please note that I only accept beer cans containing their original contents.  Once the contents have been personally disposed, I will then determine the suitability of the remaining vessel for use in my project.  So, to answer your question, I don't know which size I need.  I will probably have to try both sizes from an indetermanet number of brewers before coming to a final decision.   

[Wingnutz]

"I will probably have to try both sizes from an indetermanet number of brewers before coming to a final decision.    "

Bruce, I would like to point out that most mainstream Canadian breweries sell beer in cans of one of two sizes. While I would love to be more generous at this time of giving, financial restrictions and my own propensity to consume the contents of beer cans obliges me to limit my gift to two cans (with contents), one of each size...burp...

[bweaver]

The primary structure of the pylon is finished, shaped and lightened with lightening holes spaced relatively evenly throughout the motor mount base.  The lightening holes will also allow air movement for cooling the motors and ESCs.

NOTE:  The centre line of the electric motor shafts are going to be mounted parallel with the centre line of the plywood base of the pylon.  This will require motor mounts to be installed front and rear on the pylon.  Locations to be determined once I have decided on the motors to be used.

A battery will be installed in each hull to provide power to each motor independently. The battery wires and an esc wire will run up the inside of each of the pylon front struts. 

The two motors and ESCs will be installed in a cowl enclosure.   They will be enclosed in an engine cowl of some sort. (Refer to earlier posts with Billy Q above.) A tallboy just won't do it.  I am going to have to have a drink and think of what I will do to enclose the hardware.

The ESCs will be connected with a Y harness with one of the positive wires disconnected, in order to operate both motors simultaneously with one link to the receiver.  (See drawing)

The photo below depicts a dry fit (not glued) of
1 - the center wing component with the pylon sitting in its final position.
2 - two hulls - note I have started to shape the hull at the front of one of the hulls.

Now to carry on...

[Wingnutz]

Impressed again...a unique and innovative build accompanied by a classy beer can (an oxymoron?), even if it's an import! Bruce I had no idea how big this model is and obviously even a tall boy is woefully inadequate as a cowling.  I'm guessing a steel can large enough would be prohibitively heavy. Can you use the "firewalls"/motor mounting plates to stabilize the cowling cylinder? Perhaps "rolling your own" (cowling that is) out of depron or acetate like an EDF thrust tube would keep it light, rigid enough and still capture the character of the real cowling?
I'm sure you'll find a suitable solution and if the weather permits, I'll bring the promised beers to the Wed meeting...it'll add Canadian content to you beer menu, if not your model!

[bweaver]

Thanks Bill,

I am hoping someone can provide some guidance on the rudder and elevator servos and receiver installations.   

My earlier model had the servos installed in the hulls and the pushrods ran through plastic tubes mounted to the side of each boom, with a clevis connected to the elevator and rudder control horns.  They were dry but hard to get to when service/replacement became necessary.

As an alternative to this, I am strongly considering using 'thin wing servos', installing them in the horizontal and vertical fixed portion of the rudder and elevator stabilizers.  This will shorten up the pushrods considerably and access to the servos will be readily available.   The servo wires will be run along each boom to the individual servos. 

In my earlier model I had installed the receiver in the central wing cockpit area.

As an alternative, I am thinking of installing the receiver in the pylon along with the motors and ESCs because there is a lot of space up there and it would make it easy to get to if/when needed.

If you have any thoughts on these installations, pros and cons would be appreciated.

Thanks, Bruce

[Wingnutz]

"As an alternative to this, I am strongly considering using 'thin wing servos', installing them in the horizontal and vertical fixed portion of the rudder and elevator stabilizers.  This will shorten up the pushrods considerably and access to the servos will be readily available.   The servo wires will be run along each boom to the individual servos. "
Bruce,
My guess is that adding servos in the tail surfaces will make the cg problem worse. I read through your earlier SM thread (same beer can banter five years ago!) and if I've understood the first model, you put servos in the hulls and connected to rudder(s) and elevator with pushrods. I think you were on the right track. As a slight variation, how about using Sullivan cables to connect hull mounted servos to rudder(s) and elevator? At least then, the cable weight isn't all in the tail...I've done it on several models and as long as the outer shell around the cable is anchored, the system works well in a push/pull application.
If you locate the rx in the motor(s) pod, you'll have a pile of wires running up the pylons and the rx will be pretty close to the ESCs and motors...not sure that's a good location for reliable reception...it will also dictate a non metal cowling...
Keep us posted!

[bweaver]

Back at it.

@Crazyflyer has kindly lent me his hot wire foam cutting tool.  Not only that, he delivered it too.  Thank you so much.

I have watched a number of YouTube videos on the subject of hot wire cutting and there was sure a lot of useful information and guidance in them.

Originally, I was going to use 5 layers of 1/2 inch blue foam to make up the foam core wings.  But then I decided to break the bank and buy another 2 X 8 foot sheet of foam but this time the board was 2 inches thick.  This way I will only have to use two layers of stacked foam to make each wing.

The wing shape was traced and transferred to the foam for cutting.  I must remember that there is a right and left wing panel.  This will require the wing template to be set up differently to make the opposite wing panel. 

Ribs #1 and #10 were traced from the plans and transferred to the 1/8th inch plywood to make rib-end templates.  Both were cut out and sanded to eliminate any burrs, so that the hot wire will not bind as it glides across the templates and cuts through the foam boards.

Multiple holes were drilled in each of the end plywood rib templates and finishing nails were pushed through them into the foam board to hold the templates securely in place.  Tomorrow (duckling @davidk ) will return to assist me with the actual hot wire cutting.  The photos below depict the process. 

[davidk]

Burn pictures posted tomorrow 

[bweaver]

It's today and the foam has been cut.  Thanks Dave.

It will have to be filled and smoothed out, but it is really coming along.

Wooden trailing edges to be added to the wings and ailerons to be cut out and installed.

[davidk]

Beautiful... just excellent looking.  And that Marchetti is also looking fantastic. 

That foam cutting bow worked perfectly... cutting through that foam... like butta.

[Frank v B]

Bruce,

I love your focus on built-in flotation.  Blue foam all the way.

Frank

[bweaver]

Added more floatation to the outer wingtips and rounded them off to match the plan. 

Determined location for defining the ailerons.  Cut them out.  Then installed balsa wood for hinge points on the top of the wing and ailerons.  Filler added.

[bweaver]

Aileron servo installations. 

Servo wire passageway holes drilled through wing using a piece of tubing and electric drill.

On the bottom of wings, I cut out the servo placement compartments using a knife by making many small slices of the same depth into the foam surface.  The smaller foam pieces were chipped out using a small chisel type tool.  The base of the servo compartment surface was smoothed out using a Dremel Dura-Grit shaping tool. 

I am using Thin-wing servos for mounting horizontally in the wing.  The servos are going to be mounted (screwed) to a 1/8th ply base that will be varathaned and glued in place. (Varathaned to protect the wood from water.) A cover plate will be placed over the servo compartment later.

To protect the servo from water, I was going to completely paint the servos with this silicone conformal coating.  Has anyone had any experience with this?

[bweaver]

The pylon motor mounts have been constructed to accommodate two electric motors and escs.
The pylon has been varethaned to protect it from moisture.  The pylon will be painted white before final installation into the central wing area. The external finish of the motor mount compartments and cowlings will be finished after the motors and ESCs have been installed.

The throttle control wire will be run down a pylon strut and fished into the rear wing receiver area.  Each ESC battery wire will also run down a pylon strut and fished into each hull battery compartment. The battery wires from each ESC have been lengthened by soldering so that the only electrical battery connection in the wiring will be made at the battery compartment.

As you can see from the photos the foam construction technics have become more sculpting than building.  It has been fun, but obviously it isn't a race.  I'm pacing myself so that I can try to think ahead to ensure all components will be accessible in the future should repairs or replacements become necessary. 

All servos are in place.  I am going to take Billy's advice and use the Sullivan cables for the rudder and elevator pushrods.

I think the photos speak for themselves.

[davidk]

It's beautiful... and currently looks like something straight out of the mind of George Lucas and Star Wars.
The pylon looks like an Imperial Walker.

I can't wait to see the wings on.

I had to go look up what Sullivan Controls are... very cool.