Peter Jenkins Posted May 18, 2014 Share Posted May 18, 2014 BEB - thanks for that info. The theoretical rpm with a fully charged 6S (25.2v - allow for voltage drop say 22 volts) gives us 490 x 22 = 10,780 rpm. Could be higher if your pack is new and internal resistance low so voltage drop is not as great. Proof will be when you fly it and see if there is any noticeable difference! Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted May 24, 2014 Author Share Posted May 24, 2014 Well I've been away with work the last week so I haven't been able to complete the finishing touches; recovering the nose, installing the radio gear (changed over to Taranis), setting the throws etc. I was planning a trip to Greenacres this weekend for their first fly in of the year, but its been raining all day and frankly a 24 hour journey home yesterday dulled my appetite for a 100 mile drive! So, I've managed to do all the final bits - and here she is in all her glory, all dressed up but sadly nowhere to go,...yet,.... And from the front,... And, before anyone asks, no that isn't a whopping big gap behind the spinner - its a white spinner with a black back plate! Honest! Let's see how see flys - maybe tomorrow or Monday for her second "Maiden" depending on the weather. But its definitely and improvement on how we started,... I'll post when she's flown. BEB Edited By Biggles' Elder Brother - Moderator on 24/05/2014 23:40:34 Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted May 24, 2014 Share Posted May 24, 2014 Very nice BEB. Look forward with interest to your flight report. Quote Link to comment Share on other sites More sharing options...
Phil Winks Posted May 24, 2014 Share Posted May 24, 2014 looking Dave very good indeed lets hope the forecast improvement in the weather for Monday materialises Phil Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted May 24, 2014 Share Posted May 24, 2014 well done sir, that looks soooo good. bet it flies well. Quote Link to comment Share on other sites More sharing options...
Colin Leighfield Posted May 24, 2014 Share Posted May 24, 2014 BEB, that's really nice. It looks as if it's going to be the year of the Chipmunk. Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 25, 2014 Share Posted May 25, 2014 Very nice BEB Keen to hear report on the O.S. John Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted May 25, 2014 Share Posted May 25, 2014 Looks great BEB should go well Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted May 25, 2014 Author Share Posted May 25, 2014 Well chaps - just had a very close call with this model. On larger models like this with 6 servos I always use a separate Rx/Servo battery and don't rely on the BEC in the speed controller. I often use a 2s Lipo and a voltage regulator for this job. But as I didn't have a spare voltage regulator in stock and it would have meant ripping one out of another model, I thought why not just use a NiMH pack? I haven't been flying much IC for the last two years or so - so I had to dig around a bit to find some NiMH packs, eventually I found a nice 5 cell pack, charged it up and plonked it in. Yesterday was spent setting the model up - all working fine. Overnight I remembered that I hadn't put in any elevator compensation for the flaps - I know from flying it previously that it does need a bit. So this morning I program the Taranis for the compensation, put the model together again and start testing. After a couple of seconds the Tx's telemetry bursts into life and the low Rx battery alarm fires off - followed in short order by a low RSSI alarm. I switch off, have a scratch of the old bonce. Turn the telemetry screen of the Tx on, turn the model on again and the Rx voltage is dropping like a brick when I waggle the controls! Oh, funny, I'm sure I charged that battery? Check out the pack and sure enough its not holding charge! Well its in the bin, I've checked out some others and selected a new one that seems to be fine. Thank heavens for telemetry! Without it it's quite possible I could have discovered that problem 2 or 3 minutes into the maiden when the controls simply stopped responding - scary! BEB Quote Link to comment Share on other sites More sharing options...
Former Member Posted May 25, 2014 Share Posted May 25, 2014 [This posting has been removed] Quote Link to comment Share on other sites More sharing options...
Stevo Posted May 26, 2014 Share Posted May 26, 2014 Lovely conversion indeed, very practical and adjustable in all the right places. If I were critical I would use nyloc nuts on the motor bulkhead just to be sure. For me I would have left the FS engine in place as I love the sound, but that's just me! Is it up yet? It deserves to be. Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted May 26, 2014 Author Share Posted May 26, 2014 Yeap - I can report a successful, and very uneventful, "maiden" this afternoon. Scale like take off is a half throttle affair with 50% flap. Just a couple of clicks of trim and she was fine. I spent most of the first flight, once trimmed, adjusting the elevator compensation on the flaps - got that spot on, flaps can now be deployed with no discernible trim change at all. Nice slow, power-on, approach and landing into a pleasant breeze on full flap. I limited the first flight to 8 mins to be on the safe side. Checked the battery afterwards (which was hardly even warm when I removed it) and found over 50% left! So pushed the timer out to 12mins and after a flight of scale like aerobatics there was 25% left - just right, enough for a "go round" and still not over discharging the battery. Third flight I threw her about a bit - most unscale-like massive, massive, loops and long verticals into stall turns etc. Still 20% in the battery on landing after about 11.5 mins. Regarding the OS electric motor - well its as sweet as a nut. Very much with the feel of a quality bit of kit, smooth and quiet. It was the warmest component after a flight (much warmer than the battery and slightly warmer than the ESC I would say), but not to a degree that is causing me any concern at all. Its definitely warm, but it's not hot. Installing and removing the battery at the field was no problem at all and all very convenient. So, it seems I've got what I set out to get - i.e. a practical scale hack that I can fly week in, week out with no fuss. I think we can pronounce this project - a success! I'd have no hesitation in saying to anyone thinking of converting a model, designed for IC power, of these proportions "go for it" - you can end up with a model with just as much power, comparable duration and no heavier. BEB Edited By Biggles' Elder Brother - Moderator on 26/05/2014 18:08:19 Quote Link to comment Share on other sites More sharing options...
Danny Fenton Posted May 26, 2014 Share Posted May 26, 2014 Nice one BEB great result Quote Link to comment Share on other sites More sharing options...
Phil Winks Posted May 26, 2014 Share Posted May 26, 2014 Just as expected Dave nice one fella. Quote Link to comment Share on other sites More sharing options...
Tony Bennett Posted May 26, 2014 Share Posted May 26, 2014 well done sir. Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted May 26, 2014 Share Posted May 26, 2014 Well done indeed Dave. You can look forward to the banter of "doesn't sound right" from the guys jealous of just how well it performs and how simple it is to operate. Are you going to convert the ele compensation figure you've now established, into a hard setting that you can't muck up? Quote Link to comment Share on other sites More sharing options...
Peter Jenkins Posted May 26, 2014 Share Posted May 26, 2014 Hi BEB - jolly well done! Question is, is the electric setup more powerful or the same power as the IC version? Quote Link to comment Share on other sites More sharing options...
Concorde Speedbird Posted May 26, 2014 Share Posted May 26, 2014 Well done, I'm glad it goes well. The Chipmunk is a lovely aeroplane, there was a nice one at Rougham yesterday. It just goes to show how comparable the two power systems are. Just for Chris, I would never be jealous of the 'ease of use' because operating an engine is far more fun and interesting for me, not even considering the sound! Now get something with an engine up! CS Quote Link to comment Share on other sites More sharing options...
Chris Bott - Moderator Posted May 26, 2014 Share Posted May 26, 2014 I'll stick to what I'm happy with thanks CS, and I'm more than happy if you do too Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted May 26, 2014 Author Share Posted May 26, 2014 Hi, Thanks chaps. Yes I'll be "hard wiring" the elevator compensation now - just in case I accidentally move the knob and lose the sweet spot! As for power - well hard to say. Its a while since I've flown the IC version. In out and out power, there probably isn't much in it - but without doubt the electric has a lot more torque so better acceleration - as my first attempt at a take off today showed me! We had an outbreak of "squirrel disease" and, somewhat shamefaced, I had to taxi back to the start of the strip for a second run at it - to much hilarity and "helpful" comment from my clubmates! BEB Now, there are two of these motors of course,....mmmm,.... Quote Link to comment Share on other sites More sharing options...
chris larkins Posted May 26, 2014 Share Posted May 26, 2014 Great conversion and it sounds like you got the outcome that you were after, just as a side note if you buy a new black horse chipmunk it comes with glow or electric as an option, the wing is now 2 piece and more importantly if you want to make it electric the whole of the canopy lifts off for changing batteries! Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted May 26, 2014 Author Share Posted May 26, 2014 Drat! I should have sold them my conversion design! Yes this is the old one-piece wing version - and definitely wasn't "IC or electric" before I started! Its a nice flying model though, so good on BlackHorse for refreshing it and keeping it up to date. BEB Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted May 26, 2014 Share Posted May 26, 2014 Well done BEB You've had a good day then John Quote Link to comment Share on other sites More sharing options...
Biggles' Elder Brother - Moderator Posted May 27, 2014 Author Share Posted May 27, 2014 A very good day thanks John. BEB Quote Link to comment Share on other sites More sharing options...
Richard Webb 2 Posted October 21, 2014 Share Posted October 21, 2014 Ive been looking at this thread with interest as ive got a chippy mk2 and ive converted mine to electric. Its got a foxy 4120-550 motor in it but im beginning to worry its not pokey enough to get off the ground. Im running off a 6s battery with a 85A speed controller. This is my first balsa model so its a step up from my little foamies and i have to say i have concerns about how its going to fly. Any hints or tips you could give me? Thanks Richard Quote Link to comment Share on other sites More sharing options...
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