Posted by boingk |
Jul 27, 2011 @ 01:32 AM | 7,247 Views
Update on the powertrain for the HobbyKing 'Ep Old Timer' night flyer project. I've decided to use a 1700kv motor seeing as it'll give some better prop options for both speed and thrust.
Preferred prop combos with this setup are 6x4 and 7x3.5 - the latter the one for slow, cruisey 'beer-and-a-deckchair' kind of flying. With 4-cell pack and a 6x4, it'd be a lot better for aerobatics and still only have a 16A max current draw.
Posted by boingk |
Jul 25, 2011 @ 01:46 AM | 7,328 Views
So winter is well and truely here in Australia and the winds are up in the highlands. At night they usually calm down so I thought I'd exploit this by building a cruisey night flyer from the HobbyKing J3 'EP Old Timer' ARF:
This is identical to the J3 'Green' I bought from them at the start of the year to learn on, and I enjoyed that very much as a trainer so figured itd be a good mount for night flying gear and perhaps as a future FPV plane given its stable flying.
The night gear I've ordered is also from HobbyKing and is simple a few bundles of LED strips that are designed to be run directly from unused channels on your receiver. A standard 6-channel 2.4ghz receiver will have three unused Futaba/JR sockets in a 4-channel aircraft (Batt/Bind, Gear, Auxillary) and four unused socket in a 3-channel plane so these little fellows are perfect:
I've ordered sets of green, red and white lights to fit to the wingtips and tail of the J3 so I can properly orient it at night and also have a somewhat scale appearance, rather than just drape it in glowtube or LED strings.
Powertrain for the J3 will be the same as the ultimate evolution of my first HobbyKing J3 - a 24g Hextronik 1500kv outrunner with 7x4 prop (GWS EP/DD 8x4 cut down) and 3-cell 1000mAh lipo pack. This setup gave me good thrust and decent speed for aerobatic maneuvers and I've no worries with using it again.
The setup was a bit too nose-heavy with a Flightmax 350mAh 2-cell so I used a 180mAh pack instead, which is what it is flying with in the video. I managed around 8 minutes flying time - mostly at half throttle - before low voltage cutoff and the performance on tap was brilliant. Loops, rolls and Immelmans were all very snappy and the low-speed and gliding characteristics were nice, too.
Posted by boingk |
Jul 07, 2011 @ 03:16 AM | 7,155 Views
Well, following the current obsession with flying wings I've decided to modify the original 'Electric Canary' wing into one, and to hell with the plans to make a small low-wing aerobatic plane. If I feel like doing something along those lines I'll just add a tail boom and move the motor forward a few millimeters.
So, you might recognise the wing from a few posts back:
The plan is to make this an 18" flying wing with the same power system as the small 15" version in the last update, but possibly on a 3-cell lipo pack if I can accomodate a Rhino 3s 360 in it. This may also help with CG should I decide to fit a tail boom. Even if I scrap it as a flying wing and convert to a full fuselage, low winged aerobatic model I can use the dual aileron servos to program flaps.
So... thats it for the Electric Canary, but there is progress on the 15" version:
The model is now only awaiting vertical stabilisers, control links and elevons. Unfortunately I forgot to cover the wing before cutting the stringers and adding the motor box... so the covering on the top side is quite average. I may redo this as the trailing edges are pretty woeful, but then again I may not. Part of the complication arises from the fact that I'm only using a regular household iron, which is cumbersome at this scale.
Anyway, more as it happen. Maiden might not be for some time due to galeforce winds striking this side of the country but I'll keep everyone posted regardless.
This is just something which is keeping me entertained between shifts at various pubs and bottleshops around town, sometime at work as well if its quite enough at the bottle-o.
The wing design is heavily modified from the '1/8A LaStick' plans and uses 8 full wing ribs in combination with another 6 leading edge formers, making for quick cutting and assembly. Coating will be transparent iron-on covering film, and it has a wingspan of only 410mm/15".
The power system is all cheap HobbyKing gear as I build on a strict budget. Motor is a 10g Hextronik 2000kv outrunner propped with a GWS 4.5x4 prop, ESC a HobbyKing 8A 'Super Simple', receiver a 2.4ghz DSM2-compatible 6ch brick. Servos are 3.7g HK 'MiniMan' units and the batteries are going to be Flightmax 2s 350's.
AUW with the setup as fitted so far comes in at 58g/2oz and should only climb up a bit to perhaps a maximum of 65g/2.3oz once covering and control linkages are fitted. Most likely it'll be somewhere inbetween.
I start getting into a groove at about 1:20 and realise there is something wrong at around 2:45 and land as best I can. The 'something wrong' turned out to be a dead servo, leaving me with very skewed handling indeed!
Following the flight above I've flown about half a dozen packs through it and also added some more detailing to help with orientation. Heres how it looks now:
The black parts are just drawn on with a permenant marker and the white stripes on the wing and square on the motor box are done using an automotive oil-paint pen.
Since refitting with a servo, I've started trying to trim mechanically for neutral flying without transmitter trim. This has proven to be somewhat of an effort and may require fitting a matching servo to replace the one still remaining from the original build - although the new one is equivalently specified, I think it may differ in speed and thus causes some trimming problems.
Anywho, thats the lot for now. Stay tuned for more as it happens.