'Burky II' !..now available via Coolwind - Page 42 - RC Groups
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Jul 06, 2017, 03:52 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar

Ernie Rides Again


I had left my Baby looking dejected in the corner since my little string of incidents last year (3 unexplained but similar crashes in 3 flights) with every intention of building a replacement over winter. We now have summer again and to add to the crash damage, dust and cob webs I have also managed to snap the tail off and taken several chunks out of the foam.

3D printed models were the latest craze in the Bray household and apart from watching the print head moving around I have not had much to do during the recent bout of bad weather and at some point I picked up the bits of the Burky. Half a tube of HobbyKing Foam Cure later and my Baby looked like but was roughly the shape that she used to be (note, didn’t say repaired, she really does look that bad!!!!). I found the bits for the rotor head and even the new bearings that I had ordered last autumn so that all went back together and was bolted on. So, where did I put the electrics??? Servos (of which I suspected that 1 might be shot), gone, must be in other mode!!!! Motor/ ESC, oh yes, borrowed them to try my Skyman with a bit more power (great success, don’t want to strip it out again), receiver, no idea…..

So, I found a couple of 20 year old Graupner C351s (metal gear) which weigh around 20 grams and are ‘only’ 5 mm longer than the 12 gram Corona ones so I cobbled them in. Next up was a ‘one wired 65 gram brushless no label motor which I have no idea where it came from’ soldered to an ESC with no markings on and with the signal cable hanging off, actually, found in my ‘scrap/ spares’ box, looked about the right size so ½ hour or so of soldering, stripping and re-assembly and I had a working unit. You know the little Orange 6 ch receivers (DSM2) which to be honest I don’t trust as far as I could throw one but that have never let me down?? I had 1 lying on the bench for testing stuff so that went in to test the servos and I forgot to replace it with a ‘decent’ one so it is still in there. That only left the snapped blade, I had contacted Coolwind last year but for me they were asking too much for a replacement set so 10 minutes with some epoxy and 0.5 mm G10 fiberglass sheet had that problem fixed.

Very slight breeze last night (2 – 5 KPH) but coming from a bad direction for our strip so I went for a ‘fly or die’. Long, long run and having released the back stick going to ¾ throttle and she lifted of flat as a pancake, no problem with head speed. Anything over ¾ throttle had her pitching up pretty strongly and she was rolling right but apart from that she flew. Two circuits and a nice steep but perfectly controlled decent put her down right in front of me to adjust the pushrods. Three sets of ‘circuit, land, adjust, fly’ had her really well trimmed out hands off at pretty much any throttle setting so I settled down to enjoy the last few minutes and everything went perfectly….. Bit later the wind dropped to zero and I went for a second flight where I tried to provoke a disaster (full throttle climb outs, violent shoving the sticks around, fast forward flight), nothing, behaved impeccably for the whole 6 ½ minutes including some ‘Burky Style Low and Slow’ (Burky pilots will understand this) and a full down auto-rotating landing to top it off, really, really enjoyable flight.

So, now the bit!!!!! I really should now be motivated and encouraged to build a new airframe knowing that I have the electronics to go in to produce a smart looking, nice flying model. Failing that the absolute bare minimum would be a few hours filling, sanding and re-spraying.

Anyone want to bet that in a year’s time that I report that I have been flying an embarrassing heap of and loving every minute????

Paul( )B
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Jul 06, 2017, 02:03 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
A lot of the time when you don't worry about how they look the stress factor goes way down and the enjoyment factor goes way up...

Anyway, congrats on getting it flying!!

SteveT.
Latest blog entry: My hangar...
Jul 07, 2017, 10:08 PM
Registered User
roidspop's Avatar
Mine has a distinct bend in the fuselage now after a rapid unscheduled disassembly. I can't tell any difference in the flying qualities so I just try to ignore that funny-looking curve.
Jul 10, 2017, 03:36 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
So nicks, dents, bent fuselages and poorly glued joints add character, right???
'Cos that would mean that I can get on and just enjoy flying her without feeling guilty, right????

Around 10 more flights all without any hitches glitches or moments so I figure that whatever was wrong I have solved it. Good news on that front, BUT, somewhere, in something, I have a faulty servo, receiver or ESC just waiting to bite my Butt again!!!!!

The 'new' servos (20 year old Graupner C351s) are coping fine, actually was thinking that she seems to have more cyclic power than before and was a bit twitchy, then the penny dropped.... Cutting a long story short I now have much longer arms fitted and therefore much more throw. Couple of times climbing out I was having to be careful to keep the nose down so I got the dumb idea, full throttle, slight dive, full up and lookey there, she will loop!!!!! Obviously had to try the same again with aileron and got a nice roll too. Dialled some more Expo in and I now have my super soft floaty gentle Baby back, BUT, move the stick a bit further for a wild ride, well impressed.

I am currently using 3S 1800 Packs on my Baby but only have 2. Other evening I had flown both 1800 pack but still had a 2650 'left over', didn't look much bigger than the 1800 so I shoe-horned her in. If anything flew slightly smoother but loops and rolls needed more work, still flew fine and after a 7 1/2 minute flight I still had 3.86 - 3.89V per cell, winner...

Paul(happy)B

Jul 12, 2017, 08:23 PM
Registered User
britinoz's Avatar
Nice job Paul. If I only had those skills......................
Chris...
Jul 13, 2017, 01:25 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
Chris, I've seen your models, you do have!!!!

Honestly, it's all pretty simple (like me really), Loads and loads of tutorial videos for the drawing programs (I used Fusion 360 for this) on YouTube. Week or so and you would have a really good grasp. As for printing, load model into slicer, press slice, copy to SD card, insert card, press start, drink coffee, job done.

Paul

Paul
Jul 13, 2017, 11:51 PM
Registered User
britinoz's Avatar
I understand the coffee bit..................................I now have my Burky flying on a two blade set up and it looks pretty good.
Chris...
Last edited by britinoz; Jul 14, 2017 at 05:04 AM.
Aug 22, 2017, 03:00 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
So my Baby was up and running proudly sporting her new dummy engine, re-spayed and fully fitted out with new components.

Around 15 flights and life was sweet, then…..

Flying straight and level at around 10 meters against the wind and she flicked over in a half roll to inverted (rolled left) where the blades stopped, guess what happened next! Clean snapped the fuselage off so I glued her back together and did lots of head scratching, the only thing that came to mind was that the pack is quite old and I was at over 5 minutes so I was wondering if the ESC was hitting LVC and pulsing.
Went out last night with a bigger pack (2200 against 1800 and with a much lower IR value) and just to be 1000% safe I swapped the receiver from an Orange to my Corona all singing all dancing pretty much absolutely interference free. So, that MUST have solved the problem, right???

Flying at an estimated 30 – 50 meters against the wind, just less than 3 minutes into the flight and , half roll, blades stopped, wait for the bang . Obviously this time it made quite a mess so maybe not worth a re-build but totally stumped.

Over 100 successful flights then 3 crashes in 3 flights, nose up, blades hit prop, stop and crash. All electronic components swapped out including motor and ESC, all rotor head bearing swapped out, 10 – 15 perfect flights and then an unexplained roll followed by blades stop and crash (this time no prop strike). Next flight with new battery and receiver, same result! The only thing still niggling me (but I really can’t believe it) is the head plate……. No signs of cracking, de-laminating or fatigue but could cured resin deteriorate???? I have quite wide, light (no tip weights) floaty blades on my Baby, could the ‘spring’ function of the GF plate have softened causing the head to become unstable????

Boo Hoo, I really liked my Burky and now Ernie doesn't have a ride…..

Paul
Aug 22, 2017, 11:34 AM
It's all in the Blades!
SafeLandings's Avatar
Paul,

Almost sounds to me like you are coming out of autorotation with a roll to the left, just like if the blades arent up to speed on take off.This happened to me only a few weeks ago in the wind with a model that has been flying well all season on a new two blade set up. The conditions were very buffety and I,m sure this was the cause.
I have now moved the battery forwards a tad, this has forced me to add a degree extra of rearward tilt.
I flew it last Saturday in horrid conditions and although it was flying into dead spots of wind caused through tree turbulance dropping feet in an isntant autorotation was maintained throughout with no tendency to roll left..... though they were arse tightening flights.

Build another!

Rich
Aug 22, 2017, 12:07 PM
I fly, therefore, I crash!!!
SteveT.'s Avatar
I am just guessing, but possibly a servo that is overheating and doing something weird?

SteveT.
Latest blog entry: My hangar...
Aug 25, 2017, 02:32 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
Rich, I had a 2200 in for the fatal flight and the hang angle was actually OK with a 1300 which is what I originally flew her on with no problem and the wind was quite low and constant. Coming out of auto, yes but not convinced that it was a set-up issue....... A dodgy servo was one of the first things that sprang to my mind, they are 20 odd years old after all!!

I am tied up with another 2 projects at the moment (trying to fly Control Line successfully after I failed in 1974 and a new VTOL) but I went to pull the plan out last night and my Whippit plan was lying underneath.... By coincidence I 'acquired' a sheet of 10 mm EPP last week, not sure if it is big enough but a quick and dirty Whippit might be a good test bed for a new delta plate and servos.

Work in progress....

Paul
Aug 28, 2017, 11:35 AM
Registered User
Hi Paul

I have had a Burky now for 3 years and it is a great flyer. At the end of year 1 it suddenly started refusing to turn into any wind stronger than about 8mph. After landing there was no problem evident but the problem continued on the next 2 flights. I was using Gening 2.2 kg servos and it turned out that one of them was not strong enough to overcome the force needed to turn into wind. Changed the servos for 3.9kg ones ( HD power 1810) and have had no issues since with a good crisp response and have flown it in up to 20 mph winds.

Am not saying this is your problem but it could be something to look at

Cheers

Graham
Aug 29, 2017, 03:12 AM
Mike's Ma Maaaaaaaaan
PaulB's Avatar
Thanks Graham,

I had swapped all 3 servos out after the first series of mis-haps but the 'new' ones are from the mid 90's (Graupner C351)!!! Just going to get 3 'real' new ones when I next order, replace the head plate and see if I can know another one together. At first I was unsure whether I would replace her or not, still not built a Whippit and I do have my Crane Fly and Spyro going strong but I did like flying my Burky.......

Paul
Aug 29, 2017, 01:13 PM
Registered User
You might mount a small (key)camera to your copter to get inflight video of your servos moving your rotor head (or not moving it enough due to problems).


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