DH SEA VIXEN for 40 mm EDFs

With the other side formers glued in a start can be made on the planking.
First a beam is temporarily glued across the back to keep it all square.

The first few planks simply help to stabilise the formers.

To give the best access the duct will be planked first. Creating an "S" shaped tube that changes section from a circle to a triangle along its length and on the inside of the formers makes for a very tedious job.

Very impressive

Before the outer skin can progress the RH inlet duct has to be planked.

Actually slower to do that the first as the rather delicate structure has to be handled whereas for the first half was held firmly on the building board.

With the EDF part added to the fuselage a trial 'positioning' fit of the wings.

The above bits weigh 5.1 oz (144 g).
The next step is to install the ESCs and wire them up to the EDFs to allow the majority of the fuselage planking to be completed as in its current form it is difficult to handle without damage, however enough access will still have to be left to run the elevator servo wire.
The wings will then be fitted followed by the booms (they fit on the wings) and tail. Only then can the battery position be determined allowing the cockpit area to be completed.
Well that the 'new' plan.

The complex shape of the planking is slow going but at least the underside is more or less complete.

Some of the top planking still to do for strength and then wire up the motors and ESCs.

The motors wired up to the ESCs using "magnet" wire to save weight.

The ESCs are temporarily connected for testing..
The "bare" heat sinks of the ESCs are mounted flush in the intakes to ensure good cooling but without creating drag..

With a bit more planking for structural integrity it should be possible to do thrust test 'nose down' on the scales.

With the ESC temporarily connected to a big 2s LiPo and controlled by a servo tester the first test run of the 40 mm EDFs.

At 240 W input it is an incredibly inefficient and noisy way of creating 'not a lot' of thrust! :woohoo:
But at least you will be able to hear it

"Wow" your right, ear defenders a must, :woohoo:

There's enough draft to blow the cupboard door about!
Don't forget - with edf's, the faster the model moves through the air, the more draft you get - when static like that, the fan blades are stalling at higher rpm's, because they are quite high pitched.

Slowly creeping forward, the wings attached.

Now comes the fun bit - building the booms and then attaching them to the wings.
No idea yet how to do any of it so quite a bit of "make it up as you go along" will be required..

Eric
Not quite sure about the EDF blades stalling.
I seem to recall there is a critical pitch angle for a prop below which it cannot stall even in still air.
The EDF blades may be above that pitch angle but providing the inlet is not too restrictive the blades are not operating in still air as it is already travelling at speed down the inlet duct even when the plane is stationary.

The booms are proving to be very slow going.
They will be made in two sections. The boom and a fin section.
Rather too long and thin to plank, let alone in 2 mm, with an awful lot of bits but I have more or less completed one boom. Light enough at 7.2 g although I am not completely happy with it.

Now all I have to do is make another, hopefully better, whilst the techniques used are still fresh in my mind.

The first half of the second boom under construction.

The 'outline' of the boom to which the formers are glued is temporary and is removed once it is lifted.

At last a bit of progress.


The hole through the left hand boom is for the elevator servo wire.
They are only 'positioned' in place but are pretty much symmetrical.
The tail fin sections will be added to each boom before they are glued to the wings.
The tail plane will then be made to simply 'fit the gap' between the fins!

The first fin assembly added to a boom.

Still only resting in place.
As weight at the back is so critical the fin, like the wing, is basically a hollow 2 mm Depron structure but it does require rather more individual planks to create the smooth shape change from the oval boom to the aerofoil fin section.

I watch in awe Stephen! At this scale I would be worried about size and orientation while flying, I have trouble with my Blizzard and that's 'only' 1.4Metres