Savoia Marchetti S55X (round two a never ending story)

[Frank v B]

Bruce,

Brilliant building of the cockpit hatch.

The Monokote is ready and eager to take up its place in history.

Frank

[Michael]

Impressive!

[piker]

Awesome cockpit greenhouse!  Very nice!

And those images of the full size cockpit!  Amazing.  What a blast from the past.  You can see the pilots literally sat in the leading edge of the wing.  So cool!

Robert

[GuyOReilly]

I do not know if you have seen this video, but it is superb, just not electric and a bit larger than yours...
https://www.youtube.com/watch?v=HGGHeaImuu8&feature=youtu.be&fbclid=IwAR32BRCr0OQN9LGQ0zhTSl2x5JKNnnCtsa5g83USPpSmIKVUeQs3_19mPBY

Enjoy!

[bweaver]

Thanks @GuyOReilly , I have watched this video and a number of other videos and photos people have made available in many ways on the internet.  What a great resource for gaining ideas and seeing successes which encourage me to carry on. (Just like TEMACs Forum)

The photos below depict the evolution to date.

I am hoping to be painting by next week once all the fiberglass is completed and sanded.

The pill bottle base is going to be my new front cowl.

The last photo puts the plane size in perspective.  Katie says she's not my personal photographer and it's going to cost me.

Everyone keep well and I hope to see you soon at the field or the water side.

[piker]

The Marchetti is looking fantastic, Bruce!

[octagon]

Looks awesome Bruce. Good job. Can't wait to see it fly.

[Gregor77]

Hail to the King of Blue Foam!

[bweaver]

Thanks guys for your kind comments.

Photos 1 and 2 - The plywood hull center alignment tabs have been cut off. Everything is aligned and not going anywhere. They serve no longer any function, so begone.   

Fiberglass done. Only minor touch ups here and there.

Photo 3 - Guess what these are? No, they're not blue foam futuristic speakers.  No their not tomb stones for Bottom R and B.

If you guessed they are blue foam water resistant battery hatch covers, you are right. (Magnets yet to be installed.)

The plane is all set for painting provided we get good weather for doing it outside.

I have yet to finish off the front cowl and pylon decorative motor enclosure.  (photo's to come as future progress occurs)

[bweaver]

While examining the model, I have come to the conclusion that the booms as currently constructed will not have sufficient strength to withstand the stresses of multiple flights. The piano wire and the spruce pieces used in the construction were consistent with the expanded size of the spruce booms shown on the drawings that I had expanded by 20%.   I am just not comfortable with it.

In order to strengthen the booms, I am laminating 1/16th inch plywood strips to both sides of the top and bottom spruce boom components.  In order to reduce the lateral flexibility of each of the booms I am also going to apply a third plywood strip to the bottom of the laminated booms as well.

I have not decided if it will be necessary to install functional wire bracing in a similar manner as that used in the full size aircraft for structural purposes.  (Any thoughts on this and/or tips on how to do it?)

Photo 1 - Depicts both sides of how the battery hatches and hulls will overlap to reduce water infiltration while taking off and landing.

Photo 2 - Depicts the original booms. The horizontal tail surface has a 20 inch span. (As previously mentioned, the tail while finished as a separate structure will not be secured to the booms until after painting.)

Also in the same photo one can see that the front cowl has been cut from the base of a plastic bottle.  (The cowl is just sitting there, not secured yet.)

Photo 3 - Depicts the 4 plywood strips that I have cut from a sheet of plywood for use in reinforcing one boom.

Photo 4 - Demonstrates that I also have and use clamps when constructing models.     I am using thin CA to laminate the plywood to the spruce.

[Frank v B]

Bruce,  Looking neat.  I love the awkward elegance.

Two observations:

The booms-  The reinforcing strips look really good and should add a lot of strength.  I am wondering if any side force during a landing when one hull hits the water before the other
will whiplash the whole tail assembly sideways.  It may be worth adding some non-stretching line (spider wire fishing line) from the back end of one boom to the root of the opposite one. (a horizontal "X" pattern).

The hulls- from my hydroplane days way back, one of the rules on a planing hull was that the chines (bottom corners) had to be razor sharp and not rounded otherwise the water goes up the sides and sucks the hull into the water.  It never gets on a plane.
I googled the SM X55S and saw this video of a large model of this plane that clearly shows sharp chines.  Of course, if the first model got off the water,  larger hulls of the same shape should be able to get off the water.

FWIIW

Frank

https://www.youtube.com/watch?v=eGWXOHjjzQ0

[bweaver]

Thanks for the comments and suggestions @Frank v B .

My smaller original model was successful in getting off the water. Upon examining the bottom edges of the hulls ('chines' - I had to look that up) , they were relatively straight edges and not rounded like how I have shaped the foam hulls on this model. (Wish I had known about chines before.) 

Considering I haven't painted the plane yet and the fact that the hulls are only blue foam board, I think I may modify the bottom edges of each hull to avoid the problem of the hulls being sucked into the water.  (I am building an airplane, not a submarine, so your advice will be useful.)

I will also get some 'spider wire fishing line' and install it in the manner suggested to strengthen the structure as well. 

YPWGFFT

[Frank v B]

Bruce,

re; the chines. I can think of two simple ways of adding chines to your hulls.

1) Add small balsa tri-stock to the transition point (where the hull sides become the bottom) on the hull.  Glue the hypotenuse to the hull and let the corner stick out at 45 degrees.  The bottom of the tri-stock will deflect the water away from the side of the hull.  In boating terms, you are creating a cathedral hull, closer to the hull in the video.

or,

2) add a strip of 1/2" wide, 1/32 thick ply chine (or 1/16 but it will be tougher to bend)  Slice a groove in the hull at a 45 degree angle with a #11 blade at the waterline and make it go up at the bow so it can get up on step.  Slip the 1/32 ply into the groove and leave about 1/4" sticking out.  Glue in place.

I will Google some photos of planes with chines (the CL 215 has them) and add them soon.

Found photos of a CL 215 and the Martin Mars.

Frank

ps.  my alphabet soup sign-off was "For What It Is Worth".  I have drawn a blank on your spilled alphabet soup.

[bweaver]

Way ahead of you @Frank v B .

Using my favorite foam shaping tool, I shaped the foam hull bottom/side area in order to apply another piece of blue foam. I then cut another piece of blue foam to apply to same area.  I applied the foam glue.  Made the glue tacky like you do with contact cement, then stuck them together when really tacky. 

Once dry, I will shape the bottom to the side ending up with straight edges (a chine).  I won't be able to shave with it, but it still should do the trick and still float. (Three more sides to go, then reapply some fiberglass to the areas before painting.) I will provide more photos after the shaping is completed.

ps.  my alphabet soup sign-off was "Your Post Was Great Food For Thought".  Just to help you get your mind out of 'blank' mode.

[Frank v B]

Great Job.
I forgot I was dealing with Bruce who can solve any problem........... he creates.

Frank

ps: Love the Roger Mason "can sand anything" DuraGrit sanding tool.  It is absolutely the best.