Servo Seagull

Description

Passive articulated sail-wing gull, a new wing-system invention.

Development Log

2022-08-05 — Gull TestFlight in wind 04.08.2022 with passive articulated foam wings — A new wing design I am working on that has several flaws. Wing material is superboard 0.5mm superboard foam layered with Orcon. Passive articulation causes further instability of the inherently unstable wing configuration making this impossible to fly; although the efficiency is good, the foam is adding some flutter resistance which helps in wind but generally it is only delaying the responsivity. I will make a new version that is less articulated and uses 0.2mm foam layer.
2022-09-05 — Servo Seagull TestFlight at evening with new Wing 04.09.22 — The previous attempts didnt hold the tension on the high aspect ratio wing good enough, therefore I decided to add many foam ribs to form the airfoil, the outer part of this backswept wing uses strong reflex to add some gentle inwash and help to balance out the relatively short tail. the control is very fragile and a bit unpredictable in stronger wind and certain flight situations… motors: 2X KST-MS320 wing membrane material: ORCONfilm+0.2mm pichler superboard elastic foam (layered by spray glue) ribmaterial: 2mm superboard foam wingspan: 1060mm
2023-02-06 — Servo seagull with new passive articulated wingsystem 05.02.23 — wings have been remade an improved by invention of a new passive articulated wing system: at the end of the large front spar rod there is a wire that extends in direction of downstroke, to which the outer part of the sail wing is attached, therefore it is possible to add downwash to the sail type wing. Another string is controlling the wing twist during upstroke. After this test I am now remaking the model to flap at opposite angle of incidence (downstroke from front to back) to get more speed and make a better use of the halfway swept wingshape
2023-02-09 — Servo seagull test flight with new wing system 09.02.23 — I tried to improve the wing by adding some airfoil to the battens and have a bigger tail. actually I dont know if a bigger tail is required. the airfoil must be improved around the wing tips there is too much reflex for a forward swept part of wing. I found that because this wing is slighty forward swept, it will perform only good and stable by the right amount of in-wash at wing tips.
2023-02-11 — Servo seagull test flight with new wing system 10.02.23
2023-02-24 — Servo seagull test flight with new wing system 23.02.23 — changes in this version: the in-wash setting was set to a bit more agressive angle of attack for outer wing which is more efficient for the forward sweep wing shape and allows a lower elevator while also allowing more passive stability and more thrust during down stroke (by lowering tail the wing is moving rearwards, and tail can produce lift and thrust). the tail is also flexible and adjustable at the base by attachment with piano wire. this is to assure that the tail does not stall while flapping.