targit

Ok, as mentioned in another thread the DF seems to have a problem with occasionally falling from the sky for no good reason, a rotor didn't come off, a mounting didnt give out, your battery wasn't flat, you weren't flying near other modelers and there wasn't a Ham radio rally next door. It just seemed to switch off and drop like a rock.

To get an idea how many of us are suffering from this, and maybe get a clue as to the cause, how about we record incidents of this type in this thread with as much detail of location weather condiditions, distance from remote control (you), colour of pants etc. as possible.

I'll kick off with mine falling from 10 feet away and about 6 feet high after approx 3 seconds flight. I was in my backyard wearing blue pants. The rotors stopped and it just fell on the (luckily soft) ground. I checked it over, no visible faults, reset it and flew perfectly for 3 days now.
oops, yes thats an important one! -No Ti enabled

yvesOttawa

Was Ti turned on BTW?

laceycopter

I think this is a good thread Targit....should be very helpful to compare this information with other.
I'm STILL waiting for my SAVS... so I have no input on this problem....I hope I never have the fall out of the sky problem, but it seem everybody does at some point. I've been doing aerial photo's from my Hirobo Evo 90 for about a year. (never fell out of the sky)Now after reading about this problem me and my dad are thinking about just Canceling the order and spending the money on some better camera's for my Evo.
Lacey

TheHindmost

I may have experienced this once...I was in my front driveway, the DF was no more than a few feet away and about six feet off the ground. I heard and saw a power glitch, but it lasted for less than a second and the DF recovered without hitting the ground. I was able to land it fine after that.

Targit, are all of your motor capacitors intact? One of mine is missing at the moment...I wasn't doing anything long-range or high off the ground, so I had postponed replacing it. I have no idea if that could lead to this, but it's something to consider...

Another possibility: I wonder if somehow there's a static discharge problem?

And good point about reporting TI status, Yves...Mine was ON.

Will

Phodel

Same issue here! This has happend several time to me as well. There are two incidents where it was fatal! The first time it happened I was flying about 200ft up preparing for a video shoot of an historic site in a field in South GA (basically in the middle of no where.....no way interferance is an issue this time). Perfectly clear calm day again, Ti enabled and the Fail Safe recovery set. It did its famous 'Cut Out' like power failure but recovered four times. AFter the fourth time it wobbled uncontrollably and dropped from the sky. Luckily even at 200ft it crashed in a tall thick grassy area (broke a rotor). Well, I tried to fly it again and it would fly stable for a few seconds and then with out warning it would start to wobble and then flip out of control. In trying the trouble shoot and remedy the issue, I swapped out the frame and motor set (I keep full set of spares already assembled and tested........they come in handy when this type of thing happens). All I had to do is place the PCB on the new frame/motor set and it did the same exact thing. I do not know about you but in my mind that equals problem with the PCB! I sent it in for repairs to Spectrolutions and they fixed it with in a week or so and mailed it back.

Once again, recently, it was a perfectly clear wind free day flying around 150ft with Ti enabled and the Fail Safe set Videoing and it seemed that the power 'Cut Out', rotors stopped for a brief second or two and it recovered (3 times); right after the third I thought it best to slowly start a decent (considering my experience)but out of the Blue it started flipping............SMASH it went! It landed on its head and actually no spar's or frame supports were broken (unbelievable!); only two rotor gears and one landing support ........Unfortunatley, the PCB was GLOBBERED!! Even after the crash all the solders and capacitors are in perfect shape, connectors too (unlike Sky's). I am currently working with Spectrolutions to get it replaced/repaired (those guys are great!). This is the second fatal crash I have experienced with the cut out then flipping (How Bizzare).

Has anyone had similar incidents where the 'Flipping Out' effect follows the 'Cut Out'?

Oh and by the way I was wearing Kakhi's both times.............I almost crapped them both times! Maybe I need to consider changing them????

Phodel

targit

@lacey, I hope this doesn't put you off too much, this fault is only so annoying because it works so well the rest of the time.

yvesOttawa

For the record, I've never used Ti and never encountered the power loss.

Sky High

There are a couple of other threads that mention the sudden but short power loss mystery. I have experienced that several times but not the flipping. It seems like my incidents have mostly happened when the DF was directly overhead and at a high altitude. It has done it when not directly overhead though. I have also heard that the weakest point of your Tx antenna is at the tip so I try not to point the antenna directly at the DF. That information came from the manufacturer of a frequency checker-outer.

av8ersteve

My Feedback: (1)

Mine did it to me yesterday. It was about 15 feet away and about 6 feet up, Ti was enabled and it was a perfect, cloudless, windless evening. I was flying in an area where there are no other rc aircraft around (my backyard) but I am close to the interstate. All 4 rotors just cut out but before she hit the ground, the power kicked back in. I had it recovered but I panicked and set it down pretty hard and broke 3 supports[:@]. This is about the third time this has happened but the other two times I was high enough that it fully recovered and no damaged occurred. I'm wondering that maybe I could be getting freq hits from truckers CB's since I do live near interstate 40 (not the regular CB's but the guys that are running high power liniers). Could this be a cause?

Sky High

I have found that altitude is your friend when there is a momentary glitch. When it happens just floor the throttle and you should recover fine, if power is restored, that is. No matter what height you are, up is better than down. As you said, you were able to recover when this happened at a higher altitude. It has only happened to me once about 2 ft off the ground. The other times have been 50+ ft which gave plenty of time to recover. All of mine have been the typical 1/4 second hits though, nothing prolonged.

Aren't CBs on the AM band and DFs on the FM band?

TheHindmost

CB radios are AM and around 27 MHz...And you're right that DFs are FM, and at a higher frequency (around 72 MHz, at least in the US). The difference in modulation type doesn't change the the potential for interference, though, or outright blocking due to the higher power allowed for CBs (up to 5 watts). However, the frequencies are well separated. But that doesn't mean hits can't occur due to things like harmonics, etc., especially if power levels are high.

(Disclaimer: I'm not a radio expert. I've picked up a few useful tidbits along the way, but that's it.)

Will

av8ersteve

My Feedback: (1)

I was just wondering about the CB thing simply because I use to have (big word here is USE to) a CB with a linier that would push 700 watts (well over the 5 watt max). My neighbors complained and threatened to turn me in because I was actually coming in over their phone conversations (not cell phones but hard wired). I appreciate ANY input you guys provide and thank you for the info. By the way, I have'nt touched a CB in over ten years now.

TheHindmost

700 watts? Man, no wonder they were complainin'!

Will

av8ersteve

My Feedback: (1)

Well, I was flying today and it glitched again in the same spot that I described in my earlier post but this time I was ready for it. I didn't panic and she recovered in less than a second. We got to find out what is causing these sudden power loses.

Sky High

Are you sure that area isn't a crop circle?

www.rcgroups.com/forums/showthread.php?t=481297

intrim

Well ive been reading all the posts hearing about all the strange things perhaps TI will do when its turned on. at first i really didnt seem to be bothered with it because i never really had a trouble in regards to this issue. i started out witha df5ti all i had was a four ch radio so i had to arm ti ,right from the start. I can fly without it but not having the dual rates made it a little touchy. but i wanted a radio that actually had some features so i got the 6 ch futaba computerized 6exap that dfy has on the web. spectrolutions was fixing a loose crystal when my new radio arrived. so i waited and waited and it just arrived today. i took off my cf blades and put on the new black blades and went flying . the new blades are cool super quiet compared to cf blades. i cannot believe how much better it flys without ti turned on . sky you shouldnt have any problem flying without ti. its the blades, they provide a level of stability that does not compare to stiff cf blades. its like flying a totally different heli.the stiff blades remined me of how the rotor head on my heli is so much more responsive because of the flat angle on aerobatic head compared to a beginners heli with the blades in somewhat of a y configuration before you even turn it on. its that y angle that provides a more stable hovering craft when air vectors out at this angle. I think the same principle applies to the new blades.. well up until now i have been flying without ti. I still did everything the same like a would with the 4 ch radio. so im looking at the ti switch on the radio thinking if this thing flys this good i wonder what it's going to feel like with the ti on. no i was in a rock steady hover 4-5 feet in altitude. i got 2 solid green lights when i armed it . i am out away from any objects that could reflect heat because the df will tilt away from heat but ther wasent any sources around. it is 5 pm so i shouldnt have a problem with the wobbles during the transistion to darkness. i fliped on the ti switch and immediatly the df flipped upside down and slamed into the ground hitting the board so hard it broke the canopy and seriously tweaked the 4 thermal sensors. the board is hosed. i never did that much damage to it in a month and a half of crashes . and remember it even took off once out of site and landed on a ladys backdeck unassisted over 2 miles away. all that did was dis lodge the magnets in the motors. but this new 6 ch radio with the ti switch managed to destroy my board and i only flew it for 5 minutes. so i am overnighting back to speculations but im thinking of removing the switch because it flys so stable with the new blades i dont think you need it. but i would like to know what did this because i feel frustrated watching that german just about beat that microdrone off with a bat and its still in the air. one flip of the switch shouldnt do this its like my df forgot the ground is warmer that the sky. why else would it want to self correct its self by turning upside down. what would happen if instead of holding it up you pointed down at the ground. shouldnt it still work the only thing different would be the sensors exactly backward but how would that affect how it deals with the horizon. or do you think it wouldnt know the sky, from, say the ground? my TI is dislexic

mike

Sky High

intrim, sorry about that incident. I have to say that I learned along time ago not to switch from TI to manual in midflight. It seems that the trim settings are interpreted differently between each mode and it causes an out of control response because of the dramatic taking the pilot by surprise. As far as me flyng without Ti, no way. I fly high, real high, and it's even a challenge with Ti. You will never get the stability needed for AP without Ti or some type of assisted flying circuit. Try to fly without Ti at 100 ft + and see what happens.


Now about the new blades compared to carbon fiber. Here is what I stated about that in another thread.

www.rcuniverse.com/forum/fb.asp?m=4142160

intrim

now that i have had time to think about this,arming the ti, i wont matter it you hold the df straight up, styraight down or even sideways while arming the ti the only thing is its easier to see if the 2 lights are on while arming. and the easiest way to see if infact your Ti is on or off is to hold it level then tilt it 45 degrees to one side. as long as you are holding in this position the two lowest motors should increase in speed and stay that way for as long as your hold it in this position, the upper motors might even stop completely. this is the TI trying to level the craft. also if you accidently touch your throttle while carrying your df and radio somewhere after you have armed ti. the ti will think this angle you are carrying it in is what is level and when you turn it on CRASH unless you are high enough to recover by turning it off. so stay away from the throttle and dont accinently bump it right or you will set a new level which is wrong. I only say this because i might have easily have done this before without knowing and rack my brain trying to figure why i flipped over and it could just be suicide by pilot!!!![:@][:@][:@]

michael

TheHindmost

Hmmm...When you're calibrating the TI, the reason you hold it "eyes up" and away from your body is because then the microcontroller knows two sensors (the ones pointing up) are seeing "sky" and the other two are seeing "ground" and it can learn the temperature difference between them. It saves those measurements and uses them to decide where level is. (Level occurs when all four sensors are seeing "sky," if I understand things correctly.) So orientation definitely matters!

So if your TI was uncalibrated or badly (reverse) calibrated and you turned it on mid-flight, bad behavior isn't too surprising, although it would be nice if there were a more graceful recovery from that particular failure mode!

Will

intrim

no, orientation does not matter because all 4 sensors are identical it uses the sensors to take a sample of two different temps the code inside is what figures out what to do with it. i would like to think the program is smart enough to know the ground is warmer than the sky. how???? because the programmer set some boundries before he wrote the code. all the four sensors do is gather data. i can fly just as fast forward as reverse left or right what is now my forward sensor can just a easily be my rear if going backwards the sensors are just gathering the data for a higher power.it could possibly fly outside its boundries like in a wharehouse with a bunch of those blast heaters going. that would most difinately confuse the Ti because the boundries set are sky colder ground warmer. but in the building i think it just might want to flip upside down. that is why the board soposedly can automatically turn TI off by itself if 0 green lights but i feel the creators want to be on the safe side and force you to do it. all you have is four thermometors put them in any position you want and you will receive back the same data. that makes it even more versital. if what your are saying is true than if you hold it upside down than you have four broken sensors. you would have to be able to arm the DF someway while it is in flight but i think it could be done even in flight. but remember dont accidently bump the throttle right inless that is the position you want your df to think is level is because when you go to take off you might not even be able to trim out all the bad data you accidently entered. i think this has happened to me when i could not figure out why it is taking so long to stabilize sometimes the right motor will jump on almos making the thing want to flip and it hasent even got off the ground. but the heli thinks level is the way you carried it outside to launch. dosent it make since the right motor would come on so quickly because all its trying to do is level itself off. Im the one causing it to do some of the crazy crap it does, but now that i know and im being more careful calling out to myself when i set the levels and is this what i really want

TheHindmost

Intrim, why would DFI bother to publish a TI calibration procedure if it weren't necessary? Why would they stress to hold the DF "away from your body heat"? And why would they want you to set "thermal level" while standing a good 10 to 15 feet away from the DF?

Although the ground is warmer than the sky, the ground here may be the same temperature as the sky there, hence the calibration requirement. During calibration (if you're following the directions), the DF is being held in a known orientation, with the front sensors pointing toward the sky and the rear sensors pointing toward the ground. The program saves these sample temperature readings--which are now correct for the local conditions--and uses them when trying to self-level. But in order for it to work, it needs to be able to make an assumption about the position it's in when it's armed, hence the instructions to hold it "eyes up."

(Anyone else want to jump in here?)

Will

intrim

its easier for them to group everyone together and have them do something in a uniform fashon IE: point the dragonflyer up well now its easier to see the two green lights so thats good . its like "KISS" keep it simple stupid. i know it feels a little insulting but that is how you handle a large number of people . it narrows down the range of questions making it easier on the staff. if you are givin a task with structure then the questions are more predictable. look how we analyze the steps it takes to get in the air. how does the saying go " i believe none of what i read and only half of what I see" or "go to the refridgerator, get the box" those guys need instructions but just because you read that its the way to do it dosent necessarly mean its the only way or maybe the shortest way or the easiest way but if you do it that way then DFY at least knows where everyone's at and starting on the same page. its like working at taco bell , thinking outside the box!! i couldnt resist that one

mike

intrim

you make it sound like the only time the sensors work is if the two in front are pointed up. i still think from what i gather that it's only data. do you dispute that you wont get the same four readings if you have it upside down? 4 sensors 4 readings four of the same reading s to be interpretid by a smart software program. you are correct it is easier to hold the df up and keep your body heat away from it and the higher up you can hold it would provide better data for the TI program I'll admit i cant hold it as high when it upside down because of the switch location but i bet it would still work. maybe im giving the programmers more credit than is due but i have worked with some over the years and i dont think they would limit what the sensors are capable of capturing. enough of this DID ANYONE SEE ANYTHING WORTH BUYING AT THE BIG R?C SHOW OVER THE WEEKEND???

TheHindmost

Nope, didn't say that. I did say that the calibration process won't work if the front sensors aren't pointed at the sky (and the rear at the ground). The reason is simple: During calibration, the program wants to take measurements of the local environment. It wants to know what the sky looks like at that particular flight location, and likewise the ground. So when you're arming it, it assumes that, at that moment, the front sensors see sky and the rear sensors see ground. Then it saves those readings and uses them later when it's trying to determine whether the DF is level. It's a simple local measurement process which depends on the DF being in a specific orientation when it's performed, because the program is gathering two different temperatures (sky and ground), and has no way of knowing its orientation other than by assuming you're following the directions.

As for whether you'll get the same readings upside down, you will if you're level. Beyond that, I think we can show that the DF will try to right itself, if it doesn't run out of altitude first. But if you're inverted and level, it'll power itself right into the ground.

Will

targit

Strange that we need to go to these lengths just to determine which way the ground is, when any object with mass seems to find it with no problem...