By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by CML

Martyn's Ballerina @ 115%

It's called Ballerina 115 - sounds more impressive than Ballerina 70

All Topics | Latest Posts

Search for:  in Thread Title in  
Martyn K26/01/2016 14:05:17
5087 forum posts
3681 photos

A little bit of progress last night.

The wing tips glued into place and small gussets/reinforcement added




The real LE and TE will overlap the wing tips and add a little extra strength.

The wing halves then joined with one wing tip lifted by 2.3" (including the additional 15%).

The way I join halves is to draw a line perpendicular across the board, and making sure that the LE or TE is at right angles use this as the reference when I trim the LE, TE and spars.

I have also used a 6mm thick front to the centre rib to accommodate the 6mm dowel I will be using. The rear section is simply two ribs glued together.

Its not very clear but there is also a spruce doubler over the rear spar (1/16 x 1/4 - centre bays only) that was bent before glueing into place. Mainly to keep it together while I am handling and assembling the wing


Started work on the undercarriage bearers. The torsion legs are very long!

Following the design, I will be using a 3mm ply plate but with minor additional reinforcement. I am going to use M3 captive star nuts and will screw the u/c retaining plates into these. This means that I can easily remove the legs to simplify storage. We will see if it works

The undercarriage plate is also one piece for both wing halves. I have cut through the top ply layer (in the centre) and nicked the middle layer then cracked the plate at the centre line - photos to follow. When I glue the plate in, I'll fill the cut with a little epoxy to provide a little additional strength.

I have also added 2 more R1A lite ply doublers at the outer ribs as well. I am still thinking about adding more as the model will be heavier than the original design but in the main, I am still using the same sized material. I think the triangle stock will probably suffice though - but I'll definitely be using larger section wood for these.


Outer doubler


Inner doublers.

You will also notice a small brace - added while I was joining the wings - just to keep everything in line until the glue dries and the sheeting has been added.

This morning before I started work, I added the first of the LE sheets. Note the wing is weighed down while the glue dries


(Apologies that the pegs aren't colour aligned - I am fixing my OCD and learning to live with the discomfort)

That's about it - probably wont get much more done today as I have a club committee meeting tonight

More to come.


AndyD26/01/2016 22:15:58
771 forum posts
553 photos

love those wing tips wish i had the patience,last time i done that was in the 80s on a pitts special and had 4 to do,proberly why i dont like wings.

Martyn K27/01/2016 09:56:37
5087 forum posts
3681 photos

The great thing about laminated tips is that only one template is required and this has two purposes, it sets the shape for the wing tip and also sets the cutting angles for the LE, TE and spars to butt up against it. You also know that your wing tips will be exactly the same shape...

It takes about 10 minutes to cut and sand the template to shape, and about 2 minutes to cut the strip, 30 minutes soaking - but the boring bit is that once glued it takes about 24 hours to dry. However, it isn't attached to the model at the point so you don't have to twiddle your thumbs.

To me, that is far quicker and far less effort then carefully cutting all those odd shapes with pointy bits that always break off and will never be as strong as a laminated wing tip. I can't ever imagine that I would go back to built up wing tips again. Too much hassle


Martyn K28/01/2016 09:29:51
5087 forum posts
3681 photos

The other half upper LE sheet has been added. Next job - Undercarriage blocks..

I am basically following Peters design here except adding captive nuts so that I can use M3 bolts to secure the U/C legs and remove them for easier and safer storage. As the model will be heavier, I am adding a little extra reinforcement.

First job was to add a couple of beech blocks to the centre ribs after the slot for the U/C plate had been cut. Its quite easy to cut the slot in situ by the way. I have added lite ply doublers (R1A) at the inner and outer ends of the plate. The plate was cut to fit the slot and then laid over the ribs so that it is pushed into the two outer ribs. With a scalpel, mark the position of the plate on the remaining ribs and then cut out the slot, checking with the plate that the width and depth is correct.


Clamped into place and allowed to dro. A slight bevel needs to be cut as the centre rib is vertical to allow for the dihedral


While the glue was drying, I fitted the Rudder Elevator servo tray.Ply side plates and triangle section supporting the 4mm ply plate. No rocket science here.


The plate was laminated following the plan - 3mm birch main plate and 3mm lite ply torsion leg channel plates. I have added additional 3mm birch plates to support the captive nuts. These are butted up against the ribs to provide additional torsional support. Additional triangle support has also been added - both sides of the ribs and slightly longer than the plan suggests


U/C legs were bent up last night. My legs are 25mm longer (more than 15%) to accommodate the 13" prop I will be using


Wheels are quite nice as well. And quite light as a bonus. Using a domed 8g collet to finish them off


The holes for the bolts. I am using 16g aluminium saddles to hold the legs in place secured with 25mm M3 bolts.

Quite pleased with that. I need to add a little epoxy to the edges of the star nuts . I don't want them coming adrift!

More to come


AVC28/01/2016 10:23:37
539 forum posts
147 photos

Very neat building Martyn thumbs up

I've got one question: do you think that the aluminum saddle and 3mm bolts are necessary, or is it "additional security"? Clearly there's nothing wrong with it and for sure you'll have issues with legs falling off, but in my eyes it looks a little bit overkilling.

AVC28/01/2016 10:34:29
539 forum posts
147 photos
Posted by AVC on 28/01/2016 10:23:37:

Very neat building Martyn thumbs up

I've got one question: do you think that the aluminum saddle and 3mm bolts are necessary, or is it "additional security"? Clearly there's nothing wrong with it and for sure you'll have issues with legs falling off, but in my eyes it looks a little bit overkilling.

Marty, forget my last comment. I've read your post about removing the UC, and it makes a lot of sense to use bolts and not screws...

Martyn K28/01/2016 12:01:53
5087 forum posts
3681 photos

No problem

john stones 128/01/2016 14:31:59
11590 forum posts
1517 photos

Posh wheels/ballet shoes Martyn nice bit of rake on it to stop her tripping up as well smiley


AndyD28/01/2016 22:35:35
771 forum posts
553 photos

glad you mentioned useing longer legs,i havent checked prop clearance on mine,not sure what prop size im useing yet,i got a feeling i might be making new ones.

Martyn K01/02/2016 08:52:27
5087 forum posts
3681 photos

(1) A bit lax with the blog updates. I didn't actually get much done last week, work has been very busy and consequently been a bit shattered in the evenings. Did get some work done this weekend though.


Wing tips sanded down -initially rough and then fine. Needed as the lower sheet goes right out to the wingtip


With the U/C blocks completed I added the lower LE D box sheet. Lots of pins and pegs again.


And the vertical web added. Note I put my web on the rear of the spar rather than the front. I find it easier to fit. I also believe that it makes the wing torsionally more rigid and the spars get enclosed with the the 'D' box


Then we played a game called hunt the screw holes for the Undercarriage


Fitting the TE. Mine is laminated from a balsa/spruce strip. I have started using spruce as a boundary on many of my aeroplanes recently. Helps prevent dings and keeps a nice sharp edge.


Note that the strip is - too thick - it will be sanded down - and also locks the aileron - I'll separate it much later.

Part 2 follows

Martyn K01/02/2016 09:09:24
5087 forum posts
3681 photos


Fitting out the radio bay


This is the layout for the servos and switch. Standard sizes servos. for Rudder and Elevator and a mini for the throttle and Ailerons (2)


The LE sheet added on the upper side of the wingtip. Lots of clamps while that compound curve was eased into place.


The area where the wing bolts pass through has been blocked up between the upper and lower sheet and finally a piece of 1/16 ply inlaid.


With the wing fitted - it did with very little adjustment I added the 5mm birch plate for the captive nuts, with additional triangle (top and bottom_ for additional support. a 3mm liteply plate locks the tubes for the pushrods. Allowed to dry


At the rear, a small piece of 3mm birch ply has been inlaid for the steerable tail wheel. I am fed up of ripping steerable tail wheels off on 3 point landings.


The push rod tube exits have the tubes roughened up - gets rid of any release agent that may be present and provides a good keying area. Slow epoxied on the inside.


And on the outside - epoxy and micro-balloons


While that was drying, the LE dowel was fitted. The photo looks a bit odd - its raked upwards by about 10 degrees, it looks a lot more in this photo.


The tube outer epoxied into place at the cockpit end. Short lengths of inner pushed in and jammed so that the tube outlet remains straight and pointing to the servos while the glue dries.


Fitting the steerable tail wheel. The steering arms plugs into a hole on the bottom of the rudder. Here, I have epoxied in a short length of Nylon. This additional width adds a great deal of extra contact area for the glue - and importantly = lets me get the tail wheel assembly out


Add a lite ply support for the tail wheel assembly


Jobs a good one.

Continued in (3)

Peter Miller01/02/2016 09:13:34
11205 forum posts
1321 photos
10 articles

Have you sheeted the entire tip?

Martyn K01/02/2016 09:21:30
5087 forum posts
3681 photos


Seating the wing -

Its not a bad fit..


One thing that I forgot to mention is that I have had some 3/16 doublers around the inner wing seat area to give a larger contact area for the wing


Drilled and added 2 M4 Captive nuts. The wing is held in place by 2 steel cap head bolts. Overkill - I would normally only use 1 bolt but there is only one LE peg on this wing

You can see the 1/16 ply reinforcement plate that has been added


With the wing fitted, I couldn't resists a bare bones shot of a naked Ballerina


OK - 2 shots


My aileron mounting plates. I recess my ailerons as much as possible so that only the arm sticks into the airflow. This is the way that I do it.

A 3mm lite ply plate with a correct sized hole cut. 3mm ply behind the screw holes. The build up the frame - in this case with 6mm square balsa to provide the contact area for the film covering. Seems to work OK for me and looks quite neat.

Finally, any filling of small dings etc and then a final sanding down and then I covered the wing last night. No Scallops here though - sorry Peter


This is the top surface - the underside is predominantly dark red but will have white transverse stripes (for orientation. Model covered in Solartex

Coming along nicely and the end is in sight

More to come






Edited By Martyn K on 01/02/2016 09:39:09

Martyn K01/02/2016 09:24:35
5087 forum posts
3681 photos
Posted by Peter Miller on 01/02/2016 09:13:34:

Have you sheeted the entire tip?

No just the LE section, top and bottom


Bob Cotsford01/02/2016 09:44:26
8626 forum posts
483 photos

With that scheme it's going to look very AstroHog Martyn, still missing your old one?

Martyn K01/02/2016 09:59:56
5087 forum posts
3681 photos

Very much.. Tempted with the large SLEC kit for the 'Hog. But keep resisting it - no space left. One of the things that attracted me to this model was the Astro Hogish appearance. I am looking forward to flying it. I think it will be a lovely stress free model to fly. I hope its long lasting.


Martyn K01/02/2016 13:19:18
5087 forum posts
3681 photos

Just trying to sort out a pilot. I thought this would represent a full sized aircraft at about 1/5 scale but the cockpit is too small. What scale pilots are other Ballerina builders going for? I think the biggest I can hope for is 1/7 at the moment - probably 1/8 scale for the normal Ballerina



Edited By Martyn K on 01/02/2016 13:19:56

Peter Miller01/02/2016 14:41:37
11205 forum posts
1321 photos
10 articles

1/6th is fine, that is what I use. I have one of the rare Assagai pilots in mine. No, you can't get them now. BOOHOO

The SLEC pilots, Jet style would do well but you might need to add a bit to the bodies.

Martyn K01/02/2016 14:44:01
5087 forum posts
3681 photos

Thanks Peter

1/5 seems definitely too big I found a large 1/7 model that I would like to use but it may be just a little too small and out of proportion.


David Hayward.01/02/2016 15:11:14
176 forum posts
97 photos

Hi Martyn, I rather fancied the same as Peter with the Pilot looking to the side but as he says, no longer available. Having looked around there seems to be quite a limited choice so I decided to look in toy shops ending up in Toys-r-us where I bought a suitably sized doll for £7. You can just see her on the shelf above my worktop. Just an idea for something different. (Just had to cut her off just below the shoulders)20160123_130940.jpg

Edited By David Hayward. on 01/02/2016 15:12:23

All Topics | Latest Posts

Please login to post a reply.

Latest Forum Posts
Support Our Partners
electricwingman 2017
Sussex Model Centre
Advertise With Us
Latest "For Sale" Ads
Has home isolation prompted you to start trad' building?
Q: The effects of Coronavirus

 Yes - for the first time
 Yes - but Ive bashed balsa before
 No - Ive existing projects on the bench
 No - Im strictly an ARTF person

Latest Reviews
Digital Back Issues

RCM&E Digital Back Issues

Contact us

Contact us

Magazine Locator

Want the latest issue of RCM&E? Use our magazine locator link to find your nearest stockist!

Find RCM&E!