i12fly a Ballerina

[i12fly]

I'm not planning a proper blog as I'm a slow builder but would like to post a few things that I hope will be interesting to other people.

As a habitual meddler with plans, I like to modify bits to suit my build style.

First of all I'm using closed loop rudder so having spent some time working out how best to avoid the wires clashing with the elevator snake I thought the dimensions might be useful to others doing similar.

Fair size 'holes' were made in the formers doing a TLAR approach with the side view on the plan

Then I worked out a suitable position for the horns from the fus centreline / bottom of the rudder to avoid interference

Next the exit position of the loop wires was planned using a couple of lengths of piano wire, and the slots made with a dremel. Putting the piano wire through these and into position meant the snake route could be planned

Note there is a bracket on one of the middle formers to ensure the loop wire will not touch the snake

So the dimension for the exit holes come out at:

Hopefully the rule can be read.........

[simon burch]

I've always found the closed loop wires work better if they cross. Looking at your layout, I think you would get a nicer run to each horn, but obviously this is hard to tell without the model in front of you.

Nice looking build.

Simon

[Biggles' Elder Brother - Moderator]

I like pull-pull as a control mechanism always seems to give good positive control. I've never been that keen on snakes TBH I find them fiddly to terminate. Its a personal thing of course. Might copy you here i12fly!

BEB

[i12fly]

Interesting point there Simon, I always thought they should avoid crossing so there is no wear or metal to metal (although with 2.4GHz I guess there is no risk of interference). Crossing does make it more compact.

What is the general feeling - parallel or crossed?

[Biggles' Elder Brother - Moderator]

Crossed for me - as Simon says they seem to find their line easier that way. but I don't think it makes a huge difference. I tend to use the plastic covered wire or fishing trace - so interference isn't such an issue anyway.

BEB

[i12fly]

Second mod for me is a steerable tail skid. A similar one works well on my Puppeteer. I like to isolate it from the rudder servo to reduce stress on the servo so connect it with a rubber band. OK not pretty but is practical and you don't notice in the air.

Its made using a tail wheel bracket with 16gauge wire, an 18 gauge 'arm' is soldered onto this that projects directly backwards. The idea is to set the bracket into the fus to hide most of it

A piece of hardwood is shaped and drilled to take the 16 gauge wire, the wire is roughened with a file and epoxied into the wood.. A loop of thin wire is set into the bottom of the rudder (its shown on the surface in the picture) and the arm is then attached to it using a rubber band

I'm leaving the front end of the fus unfinished at this stage now and moving onto the wing. I've left the fus extra long at the front so that I can work out the balance using the battery/ motor etc.

Next mod: I want to fit flaps, looking at split flaps like Miles Magister but I've got to make a test piece wing section first to see if the trailing edge will be strong enough..... Only problem in my head at the moment is what to use for hinges. Can anyone advise if supershrink polyester is good enough to form hinges? I've done it with solartex successfully but never tried polyester. Don't want to use hairy mylar as it would mean cutting into the rear spar!! Definite no-no.

[Lucas Hofman]

On gliders is is very common to use tape. I have used 3M crystal clear. Has functioned well for over 2 years now.

[AVC]

On the topic of "crossed" "no crossed" wires, in my experience it all depends on the shape of the fuselage; in a thin, long fuselage, they should be crossed to try and find a straight line on each wire, but if the plane is shorter and more "fatty", non crossed lines are ok, are shorter and the potential wear in the wires is avoided (especially those with plastic covering).

For the Ballerina, I'm planning to use pull-pull as well, and my plan is to apply the "non crossed" system, same as you i12fly

[Bob Cotsford]

I have a 92" 35cc Glen's Models Maule that comes with film hinges on flaps and ailerons, if it works ok on this I think you will be ok on a Ballerina.

[i12fly]

I do like to make mods to plans to suit what I like. OK it may not be right for 30's golden era style but it is a fun sporty model so I'm going to fit flaps. If they don't work out I'll make a new wing and pretend it never happened.

I'm going to do split flaps and that means revising the trailing edge design to my favourite style, so I'll make a short test piece wing section first to see if the trailing edge feels strong enough. This is the plan (OK it includes a couple of mods after building the test piece and these are shown). The plan:

The flaps will extend from the ailerons inwards towards the fus for 239m, this lines up nicely with the rib. I've not decided on the hinge method yet.

This is the end view of the test section, the ribs have a cut-out to make room for the retracted flaps. The flaps don't run to the trailing edge to preserve the strength of the trailing edge, it would be just too thin

View from above with a flap in place:

and this is how it looks from the rear, with the flap open, upside down so it doesn't drop off. The flap itself is 1/32 ply stuck to 1/16 balsa using evo stick solvent based contact glue, I didn't use it as contact though, I spread it out on the ply, added the balsa and weighed it down to set overnight -its strong and warp free

The trailing edge is just strips of 1/16 balsa which come together behind the ribs. I quite like to use this method as its light and doesn't need sanding -just a clean up.

Is it strong enough? I certainly think so, but I have used quite strong 3/32 balsa for the ribs. Right I'm going to make the first wing now, if it feels at risk of twisting then I'll add another spar, I don't think I'll need it though.

Ribs prepared:

The ribs are held together with 2 sharpened pieces of 14swg piano wire, the position drilled for each rib using the 1/64 ply template. The spar positions were cut after assembly on the wire and sanding.