Project SBSW (update 3) — wing design disaster!

I began working on the main wing again today and decided to cut the two  1m CF tube spars in two and just stick a bamboo barbeque stick in  between, like so:


Bad idea.. this means that the load and wing twisting stress will be focused on the contact points of the bamboo spar and the CF tube which can mean disaster.

At this point i couldnt really revert to using the whole CF spar as the halves are already well glued to the wing. The only option therefore is to just join the wings together permanently and charge this to experience.. $%@$!.

Still about 75% complete.. the main wings now weigh about 320g.. it will most probably weigh about 450g eventually which means I have less than 100g to complete the fuselage.  Doesnt look too good, at this rate the plane will probably weigh 1kg empty =S


Project Scratch-built Skywalker (update 1)

I began making a scratch-built Skywalker (SW) rc plane based on plans from rcgroups.  “IF” it flies and wont weigh a ton from my usual over design tendencies ill be using it for long range.  My target is it should have a base, empty weight (sans ALL electronics) of not more than 600g 800g*. Or a total flying weight of not more than 2.2Kg fully loaded with all the RC, Servos, 5000mah 4S LiPo,  APM2.6 and FPV gear etc.

So far I’m done with the cutting of the main wings and tail assembly (rudder and elevator) which took a ridiculous  amount of time: I couldn’t decide whether to put the elevator on top of the rudder (like the pre-CF tail 2013 SW) or below the tail (somewhat like the 2013 SW). Eventually decided to do the latter so i won’t have to strengthen the rudder too much. The downside is the elevator will now be more prone to landing (or crash!) damage.

Here’s the tail section:


A closer look at the the attachment points: the end of the tail spar on the right end is a ballpoint pen casing where a barbeque stick glued to the CF spar can be inserted. This is secured by PVC/plastic strips glued to the elevator and secured to the base of the rudder with a screw and nut.


..and attached to the base of the fuselage last night:



Target Empty Weight:  600g 800g.
Weight at this stage: 175g

Balance left: 625 g

* found out that the 2012 186cm SW is 700g empty.

Compact FPV Ground Station

With the addition of the EzUHF transmitter, my LRS FPV portable ground station is complete:


1) Spektrum DX6I
2) ezUHF Transmitter
3) 7″ LCD monitor
4) CF mounting for monitor
5) 12V UBEC for powering all the electronics
6) 5.8GHz Video Reciver
7) Portable DVR (on top of the monitor hood)
8) 3S 1600mah LiPO (temporary setup, I’ll eventually use a 4S 1600-2200mah to get good 12v)
9) Acrylic plastic for the EzUHF mount.

I’ve tested this setup more than week ago and was very happy with the FPV. However, the test flights were not that far, not more than 300m from home-base and the ezUHF was only transmitting at ‘LOW’ power.  So now that works.. the next is to integrate APM2.6!

EzUHF out of the box

I got the  ImmersionRC EZUHF transmitter and diversity receiver a couple of weeks ago. The transmitter package includes:  the antenna, the transmitter box, head tracker cable, power cable with an open wire, and a transmitter to rc controller cable (in this case for a futaba).   Obviously, since I’m using a Spektrum 6i I have to replace the futaba plug with a 3.5mm mono plug for the 6i’s trainer port.




The receiver comes with a data cable (for EzOSD which I didnt get) and the two diversity antennas.



The first thing  I did was upgrade the firmware of the BOTH (must be the same FW version) the transmitter and receiver to v1.43 which includes their ‘Extreme Hopping’ mode (ie frequency hopping in a larger 20Mhz band instead of the default 2Mhz).