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What would cause this?

Old 08-10-2014, 05:49 AM
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thepiper92
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Default What would cause this?

So I was at that hobbyshop getting some replacement parts for the 450, talked to the guy there who is about my age. He was showing me some stuff on the sim, and I was playing around with it too. He suggested to use autorotation in landing, cutting throttle a foot above ground or so. I tried that...did not go well. I was a foot above ground and when I flicked the switch the heli just shot up in the air about 10 feet and came down with a bad crash. Blades are toast, main gear is toast, tail blades, boom, etc. Upon further inspection is seems when I click into throttle hold, the swash plate moves, but my curves in throttle hold are the same as they are in idle up...what is the issue here?
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Old 08-10-2014, 06:48 AM
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Sounds like the throttle cut switch is not solely dedicated to kill the power....or...I'm not sure what TX you are using or how you have your rates set....but if the bird "just shot up in the air" after you cut the throttle and your curves are the same in idle-up and throttle hold that could be the problem.
Generally, idle-up curves are set for throttles between 80% and 100% of max and btw +5 to +11 degrees in idle.....to auto rotate the blades must be in a negitive pitch somewhere btw 0 degrees (flat) to -5 degees in idle........otherwise, your'e not drifting down , but still forcing lift, possibly causing a brief upward burst...very brief, not like what you experienced.

Check your duel rate and expo settings........also, auto-rotation is usefull at higher altitudes around 10'....the suggestion trying it a foot off the ground was more than likely just a safe method suggestion to practice it (in a hover) to get the feel for the rate of descent. It's really not something to try if one does not have complete command of cyclic "yaw' recovery and been flying for awhile "without heading-hold" turned on.....requiring one to control the tail idependently.

It's been quite sometime since I set-up TX ratios and blade curves for a heli, I'd have to pull out some old dusty notes to be more precise and they may not help much since, I believe, your bird is FBL....no flybar, which makes a difference with the TX settings.
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Old 08-10-2014, 06:56 AM
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He showed me in the sim at the shop, stating that is how he lands always, at least on the 300 size and up, simply because it lets you have a gentle landing. I really don't know what the issue is, curves for both are 0 25 50 75 100, so it is odd why this is taking place. The switch is only being used in throttle cut, set at 0 throttle all the way around. What happened was there was clearly enough power left in the blades to shoot the heli in the air, but it also quickly stopped the blades during the height it came down. My heli is FBL. Guess I shouldn't have listened to him...despite that is his a very good flier, it is a costly fix, cracking the frame, cause a few things to snap off. Frankly I had control of the heli fine and thought that I might as well try autorotation. During other times when I use throttle hold I already would have landed, and when I use throttle hold I gather the change in pitch when I flick the switch brings it to a 0 or ever so slight positive pitch, as I have some negative pitch when I finish landing. I have to figure this out though, as this can be a real issue if I am not careful. I'm using the 9xr with the Orange Module by the way.
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Old 08-10-2014, 07:21 AM
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Sorry I can't be more help....not at all familiar with the Turnigy 9xr or your FBL......I'm old school...after spending 7 years and over a couple of grand just keeping my "fly-bar" birds in the air.....I decided to move on (quads). Still help buddies with older machines, Spektrum and Futaba set-ups. Surprising there are plenty of them around that still fly quite well (and parts available)....just worked on a Trex 550 two days ago.....
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Old 08-10-2014, 07:51 AM
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Helis got too expensive I'm guessing? There must be some way around the problem, perhaps removing a linear pitch with throttle hold so that perhaps a negative pitch on throttle hold equals what zero pitch is on idle...or adjust to zero pitch on hold and adjusting the idle up curve to equal it.
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Old 08-10-2014, 10:22 AM
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Sorry to hear that your crashing streak hasn't yet come to an end.

The fact is that you must have either different rates/expo or different pitch curves on your throttle hold flight mode. I know you 'think' they are the same but they cant be otherwise flicking the switch wouldn't have given you more pitch (as it obviously did if the heli climbed when you flicked the switch).

The guy gave you good enough advice, practicing autos is a good idea, but it's up to you to make sure your heli is properly set up to do them. If in any doubt pull the motor wires and go through the flight modes to make sure that the swash doesn't move significantly when you go from one mode to the next.
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Old 08-10-2014, 03:20 PM
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Well now, may have found the issue, throttle cut is set at replace on throttle curve, but add on pitch. Theoretically, you would think the same pitch setting would do nothing, but then again you are dealing with a computer and it doesn't think logic, just deals with inputs. The mixes I have are from a mcpx BL setup I found online, which I use for every heli, just adjusting the throttle curve as I need it. I gather who made the setup made a mistake...and that mistake has caused some issues for me. Oh well, after this, there shall be no issues, or so I hope, have no heli to fly currently, the nano board is gone (gonna have to come up with some padding to stick on the receiver chip on the board), red bull metal gears are still being shipped and I need a new boom cover, and the mcpx...I don't even know the issue, but the tail doesn't want to work.
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Old 08-10-2014, 11:56 PM
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That's why i'd never copy someone elses programming.. you just never know what mistakes or peculiarities might be in the program. Just set up from scratch, it's not that hard and at least you know what you have programmed..
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Old 08-11-2014, 01:20 AM
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At the time I had no clue what to do, now I understand fully...other the head locking and such, but I didn't bother making it from scratch. Clearly it would have been a good idea to have done it from scratch, or this mishap would have happened, even worse that it technically wasn't my flying that caused the crash, but simply attempting something that should have made landing easier. Hopefully I'll have a new board in for the nano by the time I take my holidays, nice to have one heli flying about and not just my planes (have to finish my hurri build too, so maybe no heli will let me focus). I must admit, despite the issues and expenses I've had with helis, I seem to enjoy them perhaps more than planes...maybe it is simply the fact that I can fly even the nano in winds that make flying the inverza nearly impossible, and to be frank, it gets windy here.
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