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DH 91 Albatross

Exceptional streamlining?

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Simon Chaddock14/06/2018 00:34:08
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5169 forum posts
2708 photos

Just before starting the rear end I though I had better get the retracts working.

First cut out the wheel wells. A bit tricky when the actual retract units are completely buried under the skin!

Wheel well1

The U/C legs are bent from 1/8" SS wire.

Wheel down

Wheel down

Wheel raised.

Wheel up

As the legs have absolutely no 'give' in them the wheels incorporate some spring movement within the hub.

Sprung wheel

All 3D printed the outer covers are only glued on at their perimeter so allowing the axle to move,.not a lot (4 mm) but better than none!

A 'tyre' made of 3 Depron rings is glued on around the hub perimeter to bring the diameter up to 60 mm.

The finished wheel weighs 5.1 g

Simon Chaddock18/06/2018 11:03:58
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5169 forum posts
2708 photos

The completed retracts under test.

The original had additional hinged panels to completely cover the wheel wells when retracted.forbisherfront.jpg

However apart from the difficulty of actually moving them I fear they would be far too vulnerable for a 'non scale' grass field so they will be left off! wink 2

Simon Chaddock21/06/2018 19:28:58
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5169 forum posts
2708 photos

The L & R tail planes.

Tail plane 1

Just 2 mm Depron skins over Depron shear webs so creating a symmetrical section. Each elevator half has 3 3D printed hinges.

After much thought I decided to use individual servos (4) for each surface. Even using micro servo this will add weight right at the back but worth it to avoid complex linkage.

The servos are almost completely hidden with only the arms and horns exposed.

Tail front

The LH elevator servo.

Elevator servo

The LH rudder servo.

Rudder servo

Of course the RH servos have to be the other way round so the paired surfaces move in unison.wink 2

The RH tail plane under test using a servo tester.

Still slow going but technically all the servos are now installed but just in 3 separate pieces of the plane!

Simon Chaddock25/06/2018 12:40:11
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5169 forum posts
2708 photos

The rear portion of the fuselage is next using my usual planked Depron skin but over over the printed formers.

Fuse rear 1

Not too difficult as this part of the fuselage is a straight sided cone although it is offset vertically.

Completed

Fuse rear 2

It weighs 16 g.

The tail plane halves glued in place.

Fuse tail 1

Despite my concern at the weight using 4 individual servos was probably the right choice as the tail end of the fuselage has very little room inside!wink 2

It has been tested so the next job is to wire up the motors and the ESCs in the wing.

Simon Chaddock20/07/2018 11:25:18
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5169 forum posts
2708 photos

This is a very slow build but a bit of progress, the motors do all turn and the desired way too! Of course having counter rotating props is not actually scale as on the original they all turned in the same 'Gipsy' way - or in other words the opposite to virtually every other small engine manufacturer!  

Only 'tick over' as the wing was not restrained in any way but very slow and stable none the less.
Just a test 'lash up' so there is quite a bit more to organise the wiring and to install the BEC as well.

Edited By Simon Chaddock on 20/07/2018 11:30:23

Simon Chaddock31/07/2018 14:53:33
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5169 forum posts
2708 photos

The wing centre section showing the Lemon 'stab' Rx, the four ESCs and the UBEC.

Stab Rx

A full test of the wing functions using RC.

The final operation is to install the wing retaining bolts but to do this I also need the fuselage centre section.wink 2

Simon Chaddock07/08/2018 10:39:21
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5169 forum posts
2708 photos

The fuselage mid section built vertically using my "terribly wobbly to start with" technique. wink 2

Mid fuse 1

The formers are 3D printed.

The 6 mm Depron plate between two formers has a 3D printed surround that incorporates the 'nuts' for two of the wing hold down bolts.

Wing mount box

The holes are printed the correct size to be tapped to suite the 4mm nylon bolts.

Mid fuse 2

The completed centre section showing the wing mounting cut out.

Fuse mid wing

More small printed bits will be needed to secure the bolts to the wing.

As this is taking so long I placed the bits together to get an idea of what it will look like.01 Aug 18a

Also to convince me that some progress is actually being made!smile o

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