Fairey Delta 2

If I were you, I'd put in a main spar because I can't see that construction working.

Old Fart
You may well be right!
I am sure it will flex a bit under g but as long as the wing does not twist positively to increase the aerodynamic load any minor distortion of the duct will have little impact on the EDF.
The RH wing with the inlet duct profile cut out and fixed to the duct.

Now I have just got to build the other wing exactly the same and attach it. Then the top and bottom fuselage formers can go on. Each will be positioned in line with the wing shear webs.
Of course the full structural strength will only be achieved when the outer skin is applied.
The weak point is really the inlet ducts as they have a thin wall (and in mine the wall is even thinner to maximise the inlet area) so it provides very limited support to the first 1/3 of the delta. :ohmy:

The second wing added along with the top and bottom fuselage formers.

So far so good and it is surprisingly rigid even without the outer fuselage skin.
It will remain on the mandrel until the internal shape of the inlet ducts has been established.

At some point soon I will have to build at least part of the nose section in order to complete the inlet duct. Those inlet compound curves are a pain to do!

Looks good Q, the formers should also strengthen the wing root.

Sorry to be a complete plank but could you just explain "twist positively to increase the aerodynamic load" for me (pref in easy to understand jargon lol!)

Sarah
If a wing bends under load provided it just bends but does not twist everything is fine. Just watch a modern full size glass glider pull some 'g'. Like this!

The problem occurs if as the wing bends it also twist a bit.
If the twist increase the angle of incidence of the outer part of the wing then it will create even more lift, bend more, twist more, create even more lift and it breaks. all in a fraction of a second!

If you look closely you'll see he's dumping his ballast water at the same time as pulling the high G turn. Paradoxically gliders with high aspect ratio wings (long and thin) have some washout built in, ie when the root of the wing is at zero incidence, the tip is slightly negative. This is to reduce the likelihood of tip stall at high angles of attack. This gives rise to another problem, at high speed, because there is little or no angle of attack, the tip is negative! Which means the wing tip actually pushes down!, and the wing itself curves downwards!
Love the Nimbus, one of the last glass fibre ships, the new birds with acres of carbon fibre are apparently very rough to fly (the rigidity which gives them their superb flight characteristics works negatively on the pilots bum!) On a booming day the pilots come back with bruises all over!

Wing twist does this -

I am not sure that was a wing twist or simple wing failure. Difficult to tell but it looked like the front strut failed which of course would cause the wing to twist.

Not much to show for nearly a days work but creating the former shapes for the inlet ducts has been a real brain teaser.

Quite a bit of the existing duct and formers have now to be cut away and then re-skinned but done such a way I can get my fingers in to do it!
The alarming bit is what is in the photo represents only 1/3 of the total fuselage length! :ohmy:

Now comes the really fiddly bit - planking those inlets!

The lower half is bad enough but when doing the top half the access will be much more restricted.
Started skinning the lower half of the fuselage as all the electrics will go in the top.

Looking at 'wing twist does this' (for the umteenth time' it certainly looks as though the outer wing is pressing down on the strut, and like any good seesaw the inboard end is being pulled up. You can see how that whole inner panel just explodes. It can only be a building fault (a tiny amount of built in washout) since I can't see the Decathlon (an airobat) ever needing any!

This is a still from the video one frame before the wing completely disintegrates.

It definitely looks like almost the entire leading edge failed either through structural failure or the front wing strut giving way.
With such a low quality image it is hard to see the front strut but the rear one is clearly still in place
It was rolling to the right and pulling out of a dive at the time so the wing struts would be under additional load.

Looking at the decathalon wing departure, it looks more like it just folded backwards to me. There doesn't appear to be any load factor on the aircraft at the time apart from 1g straight and level. The pitching moment of the wing is nose down, so had it been a 'twist' related failure, the wing should rotate downwards. It looks like this one is going up. The machine is going quite fast. Drag produces quite a large force and it' looks to me that this is the highest contributing factor in this case.

With the inlet ducts nearly finished a start can be made of the cockpit and nose section.

As it is fundamentally circular and symmetrical it can be built vertically in one piece.
After some thought I have decided to limit the length of nose, at least initially, as that scale 'spike' would be just too delicate. The nose will terminate 10" short with a simple (and robust) nose cone.
Hopefully once the flight characteristics have been sorted the natural nose high landing attitude should protect a full length nose but I bet it still gets broken more often than not!

The cockpit section complete as far as possible at the moment.

The battery goes under the cockpit and is sized for an 1800mAh 3s.
This is what it looks like with all the sections stacked on top of each other.

There is another 10" of nose to go on but will maiden without it.
So far all the Depron bits weigh 4.6oz.