Finally finished wrapping the thin foam on the wings.. with all those glue I have to say they’re on the heavy side with each wing weighing approx 288g (including spars).. or a total of 576g.
This means I just exceeded my target weight for this par by at least 200g! Anyway theres nothing much we can do anymore.. just have to continue trudging on until completion.
The main wing is getting there but.. as expected things are getting a bit dicey on the weight department. The total wing weight (without the final “skin”) so far is a hefty 461g!
Here’s the work so far:
The dihedral on the wingtips requires some care to secure:
But it seems to be sturdy enough.. I know all those glue will return to haunt me in grams =(
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
Didnt have much time to do much on this project tonight but the fuselage base has now been fully glued (used up 3 sets of the binary epoxy 5 minute glue!).
Total weight so far: 246g.
That means I only have 354g 554g for the wings and the rest of the fuselage! Ack!
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.
With the addition of the EzUHF transmitter, my LRS FPV portable ground station is complete:
Components:
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!
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).
Finally got an SD DVR recorder to record some FPV videos over Britanny RC airfield. The setup has a 2.8mm lens on a 700TVL camera and a 2W 5.8Ghz Video transmitter.
The camera gets totally washed out when it’s pointed directly to the sun (I understand some cameras automatically superimposes a black dot of extremely bright objects like the sun).. not really a big issue.
The stock Yagi Antenna’s on the VTx and VRx are good enough, although once the plane is directly overhead and goes through the ‘donut hole’ video signal is lost. Simply shifting position / angle of the receiver or the Video Receivers antenna easily fixes it though. Circular polarized antennas a.k.a. Cloverleaf should give better performance.
Here’s the vid:
The long holiday gave me enough time to finish the assembly of the video transmitter and portable ground station. The $9 Carbon Fiber holder mount bracket from AliExpress.. was all the scaffolding needed to screw or tie up everything.
Made 2 flights yesterday.. the first saw the plane go into a stall.. making a beeline for mother earth from 100 ft.. recovered just in time and land behind some trees. Fortunately the plane and electronics were practically undamaged. The 2w VTx proved its worth, and continued transmitting from the ground. The second flight was better and your professional crash pilot was able to FINALLY fly real FPV (and enjoy the view!).. could not have been possible without the invaluable help from club residents Kevin, Bryan and Emil who provided the spotting and FPV flying tips!
What an excellent FPV day!
Making a simple power distribution hub is easy. However, to make sure things will work and not result to magic smoke, make sure that:
Next, prepare the materials:
Finally, solder them all together making sure that the positive wires are connected to the correct connectors otherwise.. poof! Ok here’s the end product:
Make sure to use heat shrink tubing to insulate soldered connections.