Wednesday 26 June 2019

Sky Hawk V2 Twin Fin Tail

I'm not convinced about the value of V and A tail configurations. They may serve practical purposes but seem to reduce yaw stability, and even pitch stability in turbulent wind.

So to try and improve the performance of the Sky Hawk I changed to a twin fin configuration.

Once I sorted out a twitchy elevator servo the results were very good.

Twin fins dimensions
150mm high
200mm long
50mm top

The forward extensions add strength and may help to organise the flow across the horizontal stabiliser.

Horizontal stabiliser is made from the old A-Tail halves, just cut off and glued together flat, with 20mm x 6mm depron added to the leading edge for extra area.

The wing foam flexes a bit around the boom mounts (shown by the icy pole sticks) so I may add some stiffening there

Flights with the new twin tail mod

Sunday 23 June 2019

Sky Hawk V2 Mods

This excellent 960mm wingspan A-Tail can be set up as a twin motor or a single pusher.

I really like it's size and adaptability, small enough for easy handling, but has heaps of internal space for big batteries and flight control boards. Very similar size and performance to the Talon GT

However there are a few things that can be improved.
It's a bit lacking in yaw stability, which basically means it wiggles in any wind, mainly due to the A-Tail being too small. I have added more tail area using 6mm depron which has reduced the wiggle.

The battery bay cover is flat, meaning thicker batteries will not fit. I'm using a 3000 4S which just fits, but a domed cover would allow room for Li-Ion bundles.

For the moment, to create more battery space I have cut off the nose tab and made a tape hinge for the cover

The twin motor set up is very cool and makes for a very fast plane with a sweet twin motor sound, but it's less efficient than a single pusher setup. I changed to a single 2212 980kV SunnySky motor with a 9 x 6" prop running on 3000mAH 4S. It cruises at under 4A and has heaps of extra power for fast fun. Suprisingly the weight dropped by 10g changing from twins on a 2200mAH 3S to single pusher on a 3000 mAH 4S.

I have also sliced off the boxy FPV camera mount under the nose for less drag and to reduce grass and mud entering the nose.

Flying weight - 700g without FPV and FCB
850g with all the gear.

Banggood - Sky Hawk V2 PNP / KIT 

Single motor maiden

I'm adding a Matek F411 Wing flight control board running iNav 2.1 (June 2019) with a Runcam Eagle camera and Eachine 5.8GHz 200mW VTx.

Strange behavior and crash video

Monday 3 June 2019

Smeg Head 1060mm Canard Pusher

This cruising FPV canard pusher is inspired by the Experimental Airlines APD

The original APD uses elevon mixing and a fixed canard, but I wanted to test ailerons and a separate elevator with a central fin.

Here is the Canard Center of Gravity calculator I used to get the balance right (after the maiden)

Maiden flight video

Build overview, mods and follow follow up flight

Carboard Box version