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Post by flydiver on Feb 27, 2013 21:52:32 GMT 1
Repair doesn't look that bad.
So, primary suspect is pilot error followed by lame battery (cold temps, or past abuse), or motor damage.
Could be all of the above in some measure.
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hounddog
Flight lieutenant
Ooh I Do Wish I Hadn't Done That
Posts: 80
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Post by hounddog on Feb 27, 2013 23:27:04 GMT 1
Could it be that the tail incidence is altered?
I have also this very evening had experience of a rearward CofG issue and can concur very strongly that this is very very bad.
Maiden flight of small AT6 Texan model, no instructions included but assumed CofG is in embossed circles on wings. Taped a 2p coin on cowl and pushed battery right into front of slot to achieve this.
Launched on maiden flight and flew it round gently for 3 or 4 minutes, bit twitchy in turns as just learning ailerons but it was a nice smooth flyer. A couple of aileron rolls and confidence grew.
Tried a loop and that's where everything turned bad, it refused to level off over the top and started a series of zoom climbs and stalls, application of down elevator damped it down a small amount but did nor stop it.
Took all my time to keep the wings level and in the air and was totally unable to turn it round and bring it back, so had no choice but to cut the motor.
It plunged and climbed until it went out of sight behind a hedgerow and probably went into one of the back gardens of a row of houses.
If it had gone the opposite way it would have had a soft landing on soft straw covering a field full of carrots for the winter, but I'm never that lucky.
Searched for an hour without result, the neighbours who were home at the time have looked without result but I expect I may get it back in the fullness of time when word gets round.
I figured that it is likely the battery slid back on the loop upside, altering the CofG rearwards. In my eagerness to test the plane I forgot that I needed to figure out a way to wedge the battery in its slot before doing any real manoeuvres other than straight and level and got a bit carried away.
Tail heavy and you really have no control no matter what you do with the sticks just like on the video.
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bpj1980
Flight lieutenant
Posts: 75
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Post by bpj1980 on Feb 28, 2013 1:49:50 GMT 1
So looks a little cold, no sound heard on my laptop so not sure what revs, sounds etc, coming from the motor/gearbox, could be many things, the cub can take off from a small area believe me i know, i can have it in the air on full throttle in under 2m thereabouts (cricket pitch - sideways) now i dont pull the elevator all the way back i build it up and it climbs fast, no engine or gearbox mods done to mine, its a DSM cub with Ailerons,
I agree you need alot more room than that to fly and enjoy it, i havent had the joy in flying in snow.... mostly our temps are between 25-40degrees (Celcius - Australia) so i cant comment on effects the cold may have.
Hope you sort it out soon and when you do good luck with it and enjoy,
Thats just my 2 cents worth..
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Post by kenninny on Feb 28, 2013 4:13:35 GMT 1
the repair looks ok from the pics, recheck your cg with your finger tips under each wing 2inch back from the leading edge & lift the plane up it should balance level with the nose slightly down, and I hope you were taking off into the wind not with the wind. if all checks ok your next step would be, to check the motor & gear box
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Post by thenameisdame on Feb 28, 2013 4:57:30 GMT 1
lol ya thats my plane
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Post by thenameisdame on Feb 28, 2013 5:05:36 GMT 1
how do i go about checking the motor and gear box are up to par
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Post by thenameisdame on Feb 28, 2013 5:15:16 GMT 1
and the weather wasnt cold that day prb -1 at most
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Post by flydiver on Feb 28, 2013 5:20:19 GMT 1
Cold to you and cold to the lipo may be different.
Lipos start to suffer below 40*F. Below freezing if left unprotected and allowed to get that cool before use their performance drops noticeably, as in barely fly depending on HOW cold and WHICH battery (lipos are not created equal).
The stock battery is no great power pack. It really can't take a lot of compromises. ALL the equipment in the Cub is just adequate for the job.
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Post by kenninny on Feb 28, 2013 23:44:46 GMT 1
take off the cowl and check the gear box for cracks wiggle the motor to see if there too much move ment. since that's an original cub it has a brushed motor, the brushes could be worn, try a new motor
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Post by thenameisdame on Mar 1, 2013 0:41:55 GMT 1
how much would it cost to convert my plane to brushless?
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Post by renard80 on Mar 1, 2013 1:07:28 GMT 1
I have also this very evening had experience of a rearward CofG issue . . . . Maiden flight of small AT6 Texan model . . . Launched on maiden flight and flew it round gently for 3 or 4 minutes . . . Hey, Mr Hounddog in Sussex - where did you find winds light enough to fly a model aircraft? I'm just a few miles away, in Hampshire, and it's been gusting north-easterlies all week, certainly too strong to put up a foamy with safety. I understood all southern England was the same.  I hope you are reunited with your plane. I also lost one behind some trees last year when it developed a mind of its own. Despite having my phone number on it, my hopes that it would be returned have never been realised. I wish you better luck. |
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Post by kenninny on Mar 1, 2013 2:26:59 GMT 1
with that cub, everything has to be changed, motor, esc, servos, battery, tx (transmitter), rx (receiver)
it might be cheaper too buy another rtf (readt to fly) plane.
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Post by flydiver on Mar 1, 2013 2:46:19 GMT 1
Oh (smacks forehead), I didn't even notice that. It's the OLD Cub.
You are using NiMh batteries, right?
If so, that changes some things for sure.
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Post by thenameisdame on Mar 1, 2013 3:50:05 GMT 1
its stock everything
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Post by flydiver on Mar 1, 2013 4:42:02 GMT 1
OK, once the trainer state of the art...the old Cub is now pretty lame. The battery is OLD OLD OLD. When new and FRESH it was adequate. I doubt you have a recent replacement so I'd be amazed it works at all. No wonder you couldn't take off. As stated, to go brushless will cost you pretty much everything new but the foam. A decent TX is the big cost but that's also the basis for a flying fleet. Same for a decent lipo charger (see below). Your most cost + performance effective option is to get a lipo, pull this jumper to reset LVC supercubclub.proboards.com/index.cgi?board=ts&action=display&thread=988Then down prop to the new stock 9x6, an APCe 10x5, or a GWS 10x6 HD. You must not use the stock 10x8 prop with lipo or you'll likely burn up the ESC. Yeah, the float guys do and sometimes they burn up their ESC > crash! This was VERY common conversion a couple years ago before they came out with the current blue Spektrum-DSM/lipo Cub. (I hope you got yours really cheap. It's barely worth more than a foam blank) You'll need an appropriate charger for lipo and I STRONGLY recommend you do some reading about them before you go down that path. The do have some inherent dangers (FIRE!). sites.google.com/site/tjinguytech/charging-how-tos/ |
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