English Electric Canberra - in Depron of course

Are you using a Spekky DX6i?
These have been known to forget servo orientation, if left standing with a low battery, or if you switch on then immediately off again, because something inte4rrupted. It seems the start-up takes some fractions of a second, and if bad luck catches it part-way, it gets all confused!. It's happened a few times, I can't quote numbers) where this has happened in between flights at the field!
Normal flight, good landing, park it for a cuppa and a chat, take off - splat!
Apart from the on/off switch, nothing had been touched between flights.

Interesting!
It is certainly possible that I had switched the DX6i on/off in rapid succession which might explain it.
Now I know such a fault is possible I will take care not to do it any more!

As I used my Canberra as an example of a sub 250 g (actually 246!) it resurrected a thought that I had when I first entertained building it in 2014.
As I intended to use scale engine nacelles and the Avon is a very 'thin' turbojet I was concerned that a Canberra was always going to be a marginal EDF.
At the time this suggested 2 possible alternatives:-
a) Use slightly over size nacelles with a bigger EDF but it would then have to have significantly over size jet exhaust.
or
b) Build a RB57D. The one that had over span wings on an otherwise unchanged Canberra layout although it had J57s in rather longer nacelles. I judged with the extra span would fly pretty slowly so it would manage better on a low thrust level.
A neat view showing just how much the span was increased.

Of course in the end I just built a standard Canberra B2.

But I still wonder how it would fly with the bigger wings.
The EDFs I originally used are available but are seriously expensive at over 3 times the price I paid in 2014.:woohoo: I just don't feel the needs to spend that sort of money and build a complete new plane just to satisfy a mild curiosity.

So what if I cut off the B2's outer wing panels and substituted a pair of RB57D ones.
Of course it would not be an exact scale Martin RB57D but with the minimum of work it would fly like one and it might still come in under 250 g.
By a bit of judicious cut and past I have a RB57D plan created from the one I originally built the Canberra from.

It will just need blowing up to give a span of 54" and the outer wing panels tile printed.

With the weather forecast such as it is I don't have much else to do.

Interesting idea Q. Aerodynamically, no idea. Aesthetically, to me it's looks better with the extended wing.

What weather, Q?
Flat calm, a bit grey and chilly, but you're a (pretend) Northerner - put your big coat on and get out there!
So you're now making the High Altitude reconnaisance Canberra!
Have fun.

Eric
Agreed calm at the moment but the field is very soggy and the small ridge of high pressure will be gone by this afternoon so back to 25 mph gusts with a 95% chance of rain by even 13.00 hrs today for Warrington, according to the Met Office web site.

Flat calm, a bit grey and chilly, - - - Well - it WAS!
It's now drizzling steadily!
Plan B has been scrapped, now it's plan C! [badass]

Just because I am lazy I decided to print 'masters' for each wing rib that can then be used to accurately cut a pair of ribs out of 2 mm Depron.

Only the biggest rib was actually drawn in CAD. The rest were % reduced using the CURA 'scale' function. The complete set just fitted on the printer bed so were all printed at the same time.
As I did with the B2 they are a true symmetrical section. As a sub 250 g EDF I judged minimum drag was more important than achieving the highest lift to drag ratio.

Question. With the extension in wing length will you still leave the H & V stab's the same size ?The reason I'm asking, is because from what I have been reading on model design, full scale aircraft don't scale down exactly to model size that well. The general consensus of opinion seems to favor slightly bigger tail than the real aircraft, or have I completely misunderstood ?

crash
You are correct about tail areas normally being bigger on models although I suspect some of this is to make the plane more stable as a pilot on the ground is unable to respond as quickly as an on board pilot. Of course it is possible that the arrival of stab rxs may make true scale tails easier.

As far as my B57D(ish) mods are concerned everything other than the new wing panels will be the original just to see how well it manages. Maybe not such a risk as despite its light weight it does indeed have a 'micro' 4ch stab rx in it.

I read through the complete build log to refresh my memory and had forgotten the rather unusual wing construction method.
The outer wing panels were built 'free hand' working from a 'stand alone' D box spar.:woohoo:
So the first task is to build the D box.
Front, rear, top and bottom skins with 7 ribs. I cut out all the bits for both wings at the same time.

All 2mm Depron
A bit of a nightmare to put together. The front, rear and ribs are glued in place first (very wobbly!) and then the preformed top and bottom skins go on but once complete it is remarkably stiff.

It weighs 6.8 g.

I note from the build blog the original fuselage nose was substantially modified (twice!) to get the battery in the right place and significantly repaired last year after a serious crash.
As the Canberra is already within just 4 g of the 250 g limit :woohoo: I might take the opportunity to build a complete new nose (with a Martin type cockpit canopy ) to see if I can save a few grams to compensate for the bigger heavier wings.

With both box spars built the rest of what will be tissue covered is added on.

It now weighs 10.1 g
Now to do the same for the other wing.
Then the ultra micro 2.1 g aileron servos will have to be 'extracted' from the short wings and built into the new ones.

I'd have carried the false te spar from the aileron cut-out in to the 'root' rib, to spread the load better and reduce possible twisting.
Then, I don't work with depron or such light structures!

Eric
Its not really a spar but just to provide an 'edge'. First to stick the tissue to and then the tape top hinge!
The forces created by the aileron are carried forward by the ribs, which also have 2 mm thick cap strips so become I beams, to the rear surface of the box spar.
Well that's the theory.

Today's building.

Still got the Depron leading edge to add and sand to shape.
The RH wing weighs 10.6 g, the LH one 10.8. :ohmy: but not really bothered by the difference at this stage.

I will weight the Canberra accurately and then take off one wing and reweigh it so it can be compared to a new wing when it is complete. It will take some resolve to destroy the old but perfectly flyable wings.

Started work on the new B57D nose.
First operation was to cut off the old one.

It weighs 17.4 g so that's the target to beat with the new one.