arun 0 Posted November 12, 2012 Share Posted November 12, 2012 I needed something to hack around with in the cold months, so decided to build an AcroWot ARTF Mk2. I'll only document the more interesting stuff in this thread as the basic build is easy and well documented elsewhere on the 'net. Overall model appears to be of a high build quality with nice touches such as the firewall being fuel proofed, and the hinges being dry fitted... Power plant and radio: Saito 82 turning Graupner 14x7 G-Sonic. Probably going to run 20% nitro. Hitec HS-5485HB digital servos on control surfaces, Futaba 3004 on throttle Futaba radio gear to ensure pilot error is the cause of any crashes "Upgrades": 2.5" aluminium spinner and locking adapter from Just Engines PowerChip LED landing lights from here, switchable from Tx LiFePO4 power system - no more NiMh for me! (Experimental feature but many have had success) 380cc World Models fuel tank (model comes with 270cc also made by WM so just needs enlarged cut out) So, that's all for now, here she is on the table waiting for me to get started: Link to post Share on other sites
arun 0 Posted November 12, 2012 Author Share Posted November 12, 2012 maybe when its ready to go arun you can show one of our guys who easy it is to land one (no names of course) LOL I know you're only playing, but everyone has to start somewhere mate - and none of us learned to land without the odd mishap along the way! Link to post Share on other sites
arun 0 Posted November 12, 2012 Author Share Posted November 12, 2012 well the wot 4 xl is almost finished and will be at the field for its maiden flight on sunday weather permitting Sounds good, not sure I'll be at the field due to family commitments, but make sure you post some video! Link to post Share on other sites
arun 0 Posted November 21, 2012 Author Share Posted November 21, 2012 I've done a bit of work on the lighting and power system. I'm trying to avoid gluing wings, stabs etc. with a house move now imminent, but you know how these things go... 2x 39ohm 1W resistors placed in the supply lines to the Powerchip LEDs and soldered. These draw 80mAh at 3.5V. The 1W is overkill really, but I had them handy. Link to post Share on other sites
snakeyme 0 Posted November 21, 2012 Share Posted November 21, 2012 if you have a rotary tool such as a dremel, cuting the spinner should be fairly easy and if you dont, go and invest in 1, basic kits only cost £25 from halfords Link to post Share on other sites
arun 0 Posted November 22, 2012 Author Share Posted November 22, 2012 if you have a rotary tool such as a dremel, cuting the spinner should be fairly easy and if you dont, go and invest in 1, basic kits only cost £25 from halfords Thanks for the advice Daniel. I have all the tools including tungsten carbide rotary bits and plenty of practice at it in the past. But it's not the doing that I hate, it's the perfectionist in me that dislikes the job - it's just one of those things... The challenge is getting a pair of perfectly identical and balanced cuts (usually I do a mock up on equivalent size plastic spinner). Usually I have to resort to balancing the spinner by drilling the backplate. Link to post Share on other sites
arun 0 Posted November 22, 2012 Author Share Posted November 22, 2012 if you have a rotary tool such as a dremel, cuting the spinner should be fairly easy and if you dont, go and invest in 1, basic kits only cost £25 from halfords Thanks for the advice Daniel. I have all the tools including tungsten carbide rotary bits and plenty of practice at it in the past. But it's not the doing that I hate, it's the perfectionist in me that dislikes the job - it's just one of those things... The challenge is getting a pair of perfectly identical and balanced cuts (usually I do a mock up on equivalent size plastic spinner). Usually I have to resort to balancing the spinner by drilling the backplate. Link to post Share on other sites
snakeyme 0 Posted November 22, 2012 Share Posted November 22, 2012 in that case, make a cone out of ordinary paper or card, cut out the exact shape you want in the paper/card and use that as a template, might make ur life abit easier Link to post Share on other sites
arun 0 Posted November 23, 2012 Author Share Posted November 23, 2012 Did the spinner last night, wasn't as bad as last time I tried an aluminium one. Probably helped having the PermaGrit tungsten carbide rotary bits on my Dremel which made light work of the metal and still left a nice finish. Used the coarse bit (approx 180 grade) to cut the basic shape. Fine grit (320 grade) to finish up. Have got a few scuffs on the metal, nothing some Autosol metal polish won't sort out - and of course undone with the first unscheduled landing of the model anyway! Intended outline carefully scribed with a thin marker: photo 2.JPG[/attachment] The final assembly: Link to post Share on other sites
snakeyme 0 Posted November 23, 2012 Share Posted November 23, 2012 nice work on that spinner arun, very nice indeed Link to post Share on other sites
Jimbo 0 Posted November 24, 2012 Share Posted November 24, 2012 I used Wire cutters on mine..... Link to post Share on other sites
YellowAlert 0 Posted December 15, 2012 Share Posted December 15, 2012 Here is my electric conversion for anyone interested. I'm completely converted to using studding for mounting motors now. It has lots of advantages: 1) simple and cheap (ok that's 3) 2) the studding should bend upon heavy "arrival", absorbing impact cheaply and reducing chance of breaking the fuz or bending the motor shaft 3) easily tweaked a bit for thrust-line corrections 4) easily adjusted to suit alternative motor of different length (assuming same backplate dimension, as is usually the case) Performance is kinda wimpy with the power setup taken from my Wot4, so I'll try up-propping, which I expect to do the trick as the Wot was deliberately under-propped to yield 12+ minute flights. If that doesn't do the trick I've a higher KV motor to try which made the Wot ballistic in testing but cooked the the ESC and motor - might suit the more slippery Acro airframe better for a speed fix. Yep that's a lump of lead behind the motor for CG correction - nothing to worry about really, the heavier the better during blustery winter months.. NB: the current (under-propped) setup is: Lipo: 5S 4000maH Motor: Hyperion ZS4020 12 (543KV) Prop: APC-E 13x6.5 Sam Link to post Share on other sites
YellowAlert 0 Posted December 17, 2012 Share Posted December 17, 2012 Here's a better pic of the front end stud mounting: Link to post Share on other sites
YellowAlert 0 Posted December 17, 2012 Share Posted December 17, 2012 Performance was indeed much improved with an 13x8 prop, so I tried a 14x8.5 for fun, now it really motors Static current draw is 68Amps - a bit on the high side as the ESC (70A rated) gets a bit warm. However so long as WOT is only used for relatively short bursts I think it's just about within limits. Flight times are down to 7 minutes on this prop however - just long enough IMO, and did I tell you it's really fast Link to post Share on other sites
arun 0 Posted December 17, 2012 Author Share Posted December 17, 2012 Sounds great... Looking forward to a mid-air sometime soon when we have them both in the sky Link to post Share on other sites
arun 0 Posted January 6, 2013 Author Share Posted January 6, 2013 House move complete, the build can restart! I've tidied my new workshop (big step up from the back bedroom in a terrace house!). Plan is to start with the wings as I need to install the lights and servos and get them joined over the next few evenings... [attachment=0]photo.JPG[/attachment] Link to post Share on other sites
Club Members Bravedan 106 Posted January 6, 2013 Club Members Share Posted January 6, 2013 FAR too tidy.........Nowhere NEAR enough airframes........... Link to post Share on other sites
arun 0 Posted January 6, 2013 Author Share Posted January 6, 2013 FAR too tidy.........Nowhere NEAR enough airframes........... Well, there's two out of sight and I probably either crashed or sold the rest Had to scale back a bit due to the demands of the kids, but keeping my hand in. One day I'll have 30 airframes ... Link to post Share on other sites
arun 0 Posted January 15, 2013 Author Share Posted January 15, 2013 Wings joined and lights fitted. Empennage started. Discussed some mods with Sam over weekend. Larger wheels a must. Might need to stiffen the elevator pushrod or replace with a snake system - but not sure if going to be necessary. [attachment=1]photo 1.JPG[/attachment] [attachment=0]photo 2.JPG[/attachment] Link to post Share on other sites
arun 0 Posted January 20, 2013 Author Share Posted January 20, 2013 Tail all done. Drilled the mount for the Saito 82 - what a lovely lump of metal that is!! Will need to move the throttle linkage from the standard for the model (looks like an OS FS in the instructions) but should be easy enough. Also looks like the engine needle is going to be very close to the silencer on the underside of the fuz, might be a bit fiddly for tuning. Have elected to throw away the elevator pushrod that came with the kit after chatting with Sam. Am going to fashion my own from 3 or 4mm carbon tube as described here by Darroll Cady and am making the assumption 3 or 4mm will be fine based on fact that is what is used for Pete Tindall "up to .90" linkages which I know are well thought of. Anyone have any experience of this approach they want to share as I've not tried it before? [attachment=0]photo (1).JPG[/attachment] Link to post Share on other sites
alan 0 Posted January 21, 2013 Share Posted January 21, 2013 It's looking good Arun. I've made quite a few pushrods with wire superglued inside carbon tube. I would recommend binding the ends of the carbon with cotton and superglue as unidirectional carbon doesn't have much resistance to splitting; ok to leave the binding off for smaller models though. Link to post Share on other sites
Club Members Trevor 25 Posted January 21, 2013 Club Members Share Posted January 21, 2013 I have made these using wire cyanoed outside 4mm tube bound with shrink tube. The end of the wire can be bent 90deg and inserted into a small hole drilled in the tube, for extra purchase. Use two or more shrink tubes for more strength. Cyano the shrink tube as well Sent from my MB525 using Tapatalk 2 Link to post Share on other sites
arun 0 Posted January 21, 2013 Author Share Posted January 21, 2013 Thanks Alan + Trevor, I'll let you know how I get on! Link to post Share on other sites
arun 0 Posted January 24, 2013 Author Share Posted January 24, 2013 Lots of deliveries this week, not a lot of progress due to other unwanted distractions such as work! Now have carbon/ali tube for pushrods and an alternative manifold and muffler for the engine. This weekend then should see the dreaded cowl destruction and hopefully installation of all the control runs. Few pics of the engine with the new manifold allowing a more sensible exhaust routing. Think the u/c is going to get a bit messy with exhaust residue, but better that it getting in the servos or wing/fuz joining/radio compartment. For reference in the future if anyone has a Saito 82B and doesn't like the stock muffler/mani, the part numbers I purchased from Hobbyplastic (Macgregor's UK online shop) are: SAI8074 - Muffler SAI80CL75A - Manifold [attachment=0]photo 2.JPG[/attachment] [attachment=1]photo 1.JPG[/attachment] Link to post Share on other sites
arun 0 Posted January 26, 2013 Author Share Posted January 26, 2013 Got the cowling cut today. Decided to cut some extra holes for cooling in bottom of cowling. Also found myself childishly amused by the shape of the main cut out in the cowl - clearly this plane is "all man". [attachment=4]photo 1.JPG[/attachment] [attachment=3]photo 2.JPG[/attachment] [attachment=2]photo 3.JPG[/attachment] [attachment=1]photo 4.JPG[/attachment] [attachment=0]photo 5.JPG[/attachment] Link to post Share on other sites
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