60" A4b for vertical take off

As this will be a new bigger version so it has a new thread.
The tail section is first.

The biggest former is 7" in diameter.

The problem is as the diameter increases each former has to be made 'deeper' for the fuselage to maintain adequate 'handling' strength. This adds weight. For this large diameter former the inner Depron flange is replaced with a thin narrow balsa strip.

A bit of a faff to do but it is actually slightly lighter for the same stiffness than one using just Depron.

The other change, apart from its size, is to arrange the cheat holes specifically for maximum static airflow at the cost of slightly higher drag when in flight - but as a vertical riser it will not be short of 'flight' thrust.
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Today, apart from refitting a PIR security light! , I have made the remaining 8 formers for the tail section.

The five largest have balsa flanges, #6 has a Depron flange, #7,#8 & #9 are so small they are just 3 mm Depron.

The planking completed on the big tail section and along side the small A4b for comparison.

The view inside.

The tail fin 'production' line

All 2mm Depron.

Fins now added to the rear fuselage.

Next is to mount the EDF.
To get the servos well forward I think I will build the fuselage centre section and join it to the tail. It will be big enough to mount everything working from the inside!

Watching this thread with great interest Q .

Garry

me too

Just realised I put this in the small A4b thread!
The EDF mounted between the fins.

The first inlet.

The actual inlet area 'normal' to the airflow is quite generous about twice the FSA. The intention is to allow the EDF to breath as freely as possible so as not to restrict the vital static thrust.

Spent most of the day completing the other 3 inlets which look exactly the same so nothing new to see.
The next stage is to build the fuselage centre section so 8 big 'ring' formers to make.
The first 3.

Each is made up of quadrants so that's 32 to be cut out (in 3 different sizes!) but by far the trickiest job is adding the balsa strip around the inside edge of each completed 'ring'.
To improve access the intent is to arrange that the wing can be slid into position after the whole fuselage is complete.

This is a most unusual construction photo!

The first two formers of the fuselage centre section.
The four planks are splayed out because when the are 'curved' to match the fuselage radius they become like that.
They will be drawn back into shape as the 'stack' of formers progresses upwards - honestly!

Unlike an exploded boiler it actually comes together!

Now for some more planks.

Centre section complete.

Its a bit of an exercise in emptiness!

I have four 5g servos and the lightweight snakes. I have just got to work out how and where to fit them!

The first control surface and vane.

The vane and surface are connected with a 2.5 mm diam hollow glass fibre tube which also acts as the inner bearing.
About what I expected but it is hard to imagine even four of these a tiny (22 x 21 mm) surfaces will be able to keep the thing 'balanced'!

Not entirely happy with the vane layout. Too small and difficult to assemble.
So onto the MkII

Now in 'one piece' and with 40% more 'vane' area in the EDF exhaust.

It is made up of two layers of 2mm Depron with a balsa leading edge. Each layer is sanded on its inside to give the required section (to a very fine trailing edge) before being glued together so the outer smooth skin of the Depron is retained over the whole area.

Now just got to make the other three!

The four control surfaces mounted.

It was not easy to take this picture. The tail section had to be suspended so the free moving surfaces hung down correctly.

A bit of cardboard tube in place of the fuselage confirmed that like the smaller A4b I will struggle to get the CofG in the right place even with the 1800mAh 4s battery right forward. This really means the four servos will have to go further forward than the CofG position which in turn probably suggests I will ave to alter the way the fuselage is constructed!
I shall have to think about it carefully first.