SHORT SOLENT MARK IV – 2014 WINTER BUILD

[frajolex]

I knew something was strange! I was looking for my post all the night! lol!

[wollins]

Not much to show but I got the H stabs sheeted. Didn't plan to sheet them originally since the plans called for open structure. However I think they'd be kind of fragile for my plane ... since the plans revolve around a 8 to 10 pound plane.  No way mine is gonna be that light of a weight.  As you can see I added just under an extra three ounces total by sheeting them.

Colin

[frajolex]

They really look nice and clean Collin, do you use an electric sander?

[wollins]

Nope, good ole' elbow grease! It's actually quite easy to sand sheeting cause it's very smooth to begin with. I would STRONGLY recommend NOT using an electric sander on anything that we do with these builds. 

Colin

[wollins]

It's a no brainer, you only have one option. Go back to square one and do it right. You'd never live with yourself if don't.


Jack.

Ok guys so here's where we're at. We've wasted another ten to fifteen hours or so on these darn elevator linkages and we're still not where we need to be.  As you know there are two methods I've tried so far.

1. I used some brass tubing as a female coupler installed in the ele itself, (installed straight across the bottom portion of the ele to try to compensate for the dihedral) which will mate with my male music wire coupler in the fuse.

The male coupler is a straight piece of music wire that is encased in an aluminum sleeve which serves a "bearing" of sorts. This coupler is then attached to a servo arm, which is attached to a Sullivan Gold N rod flexible rod attached to a servo etc etc. This setup worked ok but there was unacceptable binding when trying to install and remove my removable stabs. Music wire into brass tubing not the smoothest of connections unless your alignment is 1,000,000% accurate, which doing this by hand in the space I have to work with back there is practically impossible.   

The second method I tried was ...

2. I went with dual female CF couplers in the fuse to completely negate the dihedral issue. I replaced all the brass and music wire stuff with CF, since CF is not as "sticky". This worked extremely well in terms of the fit of my stabs to the fuse and the connection between my linkage couplers. The problem here though is that there was now a bit of flex and slop within the system. 

The elevators now felt "spongy" for lack of a better term. I suspect this was due to the fact that my female CF tube couplers (within the fuse) may not have the torsional rigidity that is required in this situation and may be "collapsing" when the torque of the male couplers were applied to them?

Long story short I need something that will allow me to have my stabs removable and I need my linkages completely internal. If there was no dihedral this would have been pretty simple ... I would just have to run a straight one piece coupler right across and there would been no binding etc.

However the dihedral has caused me to go with dual linkages in this second attempt ... and even this would not be a problem if I didn't need the stabs to be removable. I'd just run dual music wire torque rods short coupled to a servo/servos within the fuse and that would have been it. It's the fact that I want BOTH removable stabs AND hidden linkages that's my dilemma. 

I guess worse case scenario if I have to give up one of the desired features I'd make the stabs permanent and that would simplify things considerably but hey, I want it all! One thing I know for sure, I will not compromise on the second requirement. If these linkages are visible that would negate all my attempts to make this plane "scale", so that is not an option.

So ... I came up with a third idea ... run the control rods traditionally outside (first pic) and then cover the whole shebang within the sheeting that would "round out" that portion of the fuse.  So ... I would have the best of both worlds! Nice solid no slop linkage but still hidden! Yeh!

Well, after doing all that work ... running extra rods, doing the supporting brackets for said rods, etc etc etc, the realization dawned on me that any degree of down elevator would cause the elevator to jam against that "rounded" sheeting. (second pic) CRAP!!!!!!   What a novice mistake! (I guess ONE scratch building project doesn't take me out of "novice" category! lol!)

Lesson to other scratch building novices ... think your moves out thoroughly (every scenario) before you commit your plan to action!  So three tries ... three failures. Maybe I should give up now, admit defeat and just settle for either nice hidden linkages and no removable stabs ... or removable stabs but visible (to me anyway) linkages.    

Nope ... can't do it.  (give up that is)

So I came up with a fourth plan which is so simple (in theory, lol!) that I can't believe I didn't think of it before. I would simply run a DIRECT servo to elevator connection. Just embed a servo arm into the elevator (see third pic) and install the corresponding servo into the fuse so that when I plug my stab into the fuse, it plugs directly into the servo. Simple, easy, absolutely no slop since there is no linkage involved.


But ....

Here's the catch.  One of the big problems with this situation is that the space to work back there is extremely tight (47mm wide to be exact) as you can see from pic #4.  Good luck getting two servos butted up together base to base in that space! If only they made low profile (max 23mm tall) absolutely reliable high torque servos! Or do they? Hmmmm ....[

To be continued ... 

Colin

[Papa]

Have you measured slim wing servos? They might fit.


Jack.

[Papa]

What about that gear door servo with a singe CF rod from one elevator to the other through the end of the servo arm. It won't be fast at transition but it would be scale. Of course you would have to set the CF rod back from the hinge line to get a pivoting motion.


Jack.

[wollins]

Too slow for an elevator application.  I think this might work though. https://www.servocity.com/html/hs-77bb_low_profile.html#.VLwHoDx0yGl

[wollins]

Ok I've decided to order those low profile servos and if that plan doesn't work, I'm just gonna go with the torque rod approach, install the stabs permanently and be done with it. Not gonna muck around with this any longer cause I just have 13 days to completely finish this fuse. (structurally)  That means all the windows, all the sheeting, the keel, the nose and the canopy.

If anyone's wondering if this is ever gonna end, it will ... trust me it will. Here's the updated timetable:

Fuse - 3 .5 months. (Half of October, November, December and January.)
Wing - 2 months (February and March)
Finish details to flying stage (glassing, paint and covering) - 1 month (April)

Maiden - Sat May 2nd. (rain date Sunday May 3rd. )

Completion (final detailing ie: decals, rivets, panel lines etc etc. ) - 2 months. (May and June)

It'll be interesting to look back and see how it all turns out relative to the above timetable. lol!

Colin

[piker]

I hope you can get it all figured out, Colin.  The plane look fabulous so far!

Hey!  I'll plan to join you for that May 2 test flight with my Stranraer!

[bweaver]

Wow, you guys are really ambitious, focused and goal oriented.  I am working towards a May completion date too.  I just have to determine the May of what year? Both of your build projects and those of other club members are incredible. It is going to be great to see all these projects come to fruition and enjoy seeing them fly.


Bruce

[wollins]

I hope you can get it all figured out, Colin.  The plane look fabulous so far!

Hey!  I'll plan to join you for that May 2 test flight with my Stranraer!

That'll be a sight! Two giant scale waterboats at the same time.

Colin

[piker]

Yes!  Wouldn't it be awesome if we piled in both our planes at the same time?   

[wollins]

Yes!  Wouldn't it be awesome is we piled in both our planes at the same time?   

Oh gawd!  After all of this, I would just go jump off a cliff!

[sihinch]

We have a Cliff!