Depron Ballerina

In 2016 RCME published a full size plan of Peter Miller's Ballerina sport plane as the 2016 "Mass Build"
As it was a substantial balsa/ply IC powered plane I though it would be interesting to build one out of Depron and be electric. It ended up at just 25% of the weight, bringing new meaning to "slow & floaty".
In December 2024 it suffered a serious crash and has been untouched since.
 
So I have today made a start on the repairs.
First restoring the fuselage sides to the correct length.
 
The operation watched by the Chihuahua "Disco" sitting on my lap.
 
Looks like a cat, affectionate as a cat, but barks like only a chihuahua can and does so for no particular reason!  

 

A bit  more progress. With  the flat side plates on both sides a start can be made of the formers.
 
All a bit wobbly and tricky to avoid a "banana" fuselage but the top and bottom planking which greatly stiffens the structure can't start until all the formers including the motor mount are in.    
Just as well as I kept the plans and the stl files for its few printed bits!

The wing needs fewer repairs and is retained by 3 nylon bolts. The only problem is they did not shear in the crash but simply tore out the threaded retaining plates in the fuselage!
This rather explains why the fuselage damage all the way back to those plates was completely wrecked but the back end including the fin and tail plane was completely undamaged.
Of course it was originally built so long ago I have trouble remembering some of the construction detail I put in as I went along.   

Things moving on slowly. With all the formers in place a start can be made on the top and bottom planking.
 
The gap between the top planks is where a battery box for a 200mAh 3s will be "let in". Exactly where will be set to obtain the CG position.
Being virtually all Depron is it ridiculously light for its size so it only need a tiny motor in fact an Emax 2812 which will drive a 9x6 "e" prop.
Only160W but that will still give a quite adequate 110 W/lb! 
The original balsa/ply IC powered Ballerina weighed 4.5 lbs. The Depron Ballerina weighs 1.5 but still has the same wing area    

A short video showing the installation of the salvaged ESC and the printed threaded mounting plates.
The second part shows that it actually works. Phew!
 

Now nearly complete. Just the battery hatch to make. 
 
To keep to the super light weight theme it uses a 1500mAh 3s which has to be right behind the motor bulkhead for CG balance.
Had to order another bottle of white acrylic as my existing bottle has gone "off" as it now consists of white resin granules floating in water!
Not that surprising really as it was last used over 7 years ago.
 

The fuselage repairs are now complete,
 
With a modest battery box and hatch.
 
Suitably calm weather to try it out does not look likely for at least a week. 

Remarkably still this afternoon before next band of rain arrives. Although the ground was very wet and rather soggy in places I just had to have a go. For safety (the Lemon RX is most reliable on a true Spektrum DSM) so I bound the Ballerina to the DX6i doubling up with an existing plane as all its 10 slots are already in use. To my relief it does fly.
Not even full power for the hand launch and a bit erratic until I adjusted the trims then it flew "hands off" rather well. It was climbing so throttle back to 50% and gently float around for 5 minutes. Even included a loop. I had forgotten just how slowly it flies and that can be ridiculously slow if required.  
An easy long glide approach and a gentle flare. Stopped on the very wet rather long grass in it own length!
The new titanium white acrylic has arrived so some "smartening up" before it goes back on the wall.
        

Very wet, overcast and rather chilly but pretty calm this afternoon so at last a very poor video of the Ballerina.
The hat cam was not correctly lined up so I had to edit out those bits where there was nothing to see and most of the rest is concentrated to the top right hand corner but it does give an idea of just how slowly it flies. The glide approach is shown but the actual perfect touch down is just out of shot! 

Better video next time.   

Despite the alignment issues watching the video was a joy.  Ballerina is an apt name. Slow dancing gives plenty of time to enjoy that park setting. 

Nice flying, Simon. The vid was very jerky, though, is that the camera, or were you so cold you were shivering?

Not exactly sure about the jerkiness.
The new camera is significantly heavier than the original 808 which may make any flexibility in the head cam set up worse.
I note that in my 808 cam videos shot 10+ years ago whilst not entirely jerk free they are much better but then I am older too so maybe my head movement is now jerky and it is that my eye automatically compensates. I do consciously try to keep my head movement as smooth as possible!
I am at the moment organising a "ring sight" for the new hat cam set up so at least the plane should jerk in the centre of the screen most of the time! 

I think that it is the camera recording unit that is trying to keep up with the constant movement and failing. It is fairly well known as Latency.

Having lost the battery hatch on the last flight I decided to try to print a replacement and at the same time change its retaining method!.
It is actually quite a complex shape and took far too long to get right to be a good good fit.
A top view showing the holes at the front for the 2mm wood dowel retaining pegs.
 
A rear view showing the recess for the rear magnet.
 
The hatch finished and painted.
 
It weighs 1.8g of which 0.3g (17%!) is the weight of the paint! Mustn't grumble as it adds significant stiffness to the hatch.