TOPIC: DH 91 Albatross

DH 91 Albatross 09 May 2018 11:43 #31

  • Quorneng
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The ribs glued on to the lower skin.

Four ribs, including the big centre one, had to be reprinted as they were not quite the right size.
This would have been no problem if they had been in Depron as they could easily be 'sanded to fit' and no one would ever know! ;)
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DH 91 Albatross 10 May 2018 11:28 #32

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The interesting bit, actually doing what I imagined in my mind!
The completed wing as far as intended at this stage.

It feels slightly 'heavy' compared to say the A350's wing but is admirably stiff, probably unnecessarily so, but I was concerned at the weight of the 4 motors on the wing, not for flying loads (they actually distribute the load) but in any sort of any sort of hard landing.
One problem is that with my rough grass field it will not belly land well. The bottom of the fuselage is level with the under side of the wing so there is nothing to 'slide' on. As a result it will probably ground loop very easily and likely breaking off those low mounted tail fins in the process! :woohoo: .

Now the boring bit - making the other wing, but at least I have already cut out and printed virtually all the bits. ;)
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DH 91 Albatross 13 May 2018 00:37 #33

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The two wing halves joined.

In this state the wing weighs 115g which of course includes the retract inits.
Still a bit of sanding to get both halves of the wing to the same standard, then its cutting out the wheel wells to ultimately get the retracts working. ;) .
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DH 91 Albatross 14 May 2018 13:53 #34

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You have a record of success with challenging projects and this must be one of the most challenging! I envy your progress with the practical use of 3D printing.
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DH 91 Albatross Today 09:34 #35

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With the Big Dragon 2 rebuilt and flying attention can return to the Albatross.
I used 'printed' hinges for the A350's rudder. All the other surfaces use tape hinges.

They work well enough but are not very strong so a better more robust version that will be used for all the control surfaces of the Albatross.

The two parts simply 'click' together and it can be 'scaled' in CURA to a suitable size but below 75% the hinge 'pin' (at that scale it is only 1.5 mm in diameter) does not print well enough to retain all the required diameters.
The air frame side of the hinge will be glued to a printed rib. The other side is simply glued into a slot in the solid Depron control surface.
If possible I would like to use surfaces 'direct coupled' to the servos as in 2.4 individual centring, range of travel and differential movement can be incorporated. The 'thorny' problem is how to do the rudders in a way that is both simple and light!
The lightest of all is of course "bank & yank" (no rudder) but that might not be a good idea with the inertia of 4 motors out on the wings and with a rather modest fin area.
This could be a significant issue as on the prototype the fins/rudders were enlarged and moved to the ends of the tail plane to overcome directional control issues!
Last Edit: Today 09:36 by Quorneng.
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