drops while hovering

drops while hovering
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drops while hovering - 1/24/2010 11:43 PM

jfast

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any ideas on why my heli drops while in a steady hover? it will do this even inside with no wind.

trex 450 se v2

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RE: drops while hovering - 1/25/2010 12:43 AM

dknovick

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quote:

ORIGINAL: jfast

any ideas on why my heli drops while in a steady hover? it will do this even inside with no wind.

trex 450 se v2

Bad battery?
Radio glitch?
ESC cutting out?

-Dave

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RE: drops while hovering - 1/25/2010 3:10 AM

Flying Foot Doc

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Servos not centering? Andy

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RE: drops while hovering - 1/25/2010 3:16 AM

jfast

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rpms , seem to stay steady, so i don't think it is a motor or battery related issue, i heard something somewhere, poss pitch curve issue?

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RE: drops while hovering - 1/25/2010 4:40 AM

dknovick

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quote:

ORIGINAL: jfast

rpms , seem to stay steady, so i don't think it is a motor or battery related issue, i heard something somewhere, poss pitch curve issue?

But you're in a steady hover, you shouldn't be moving around that much in the throttle/pitch curve...
(and it's something that's easy to check).

Flying Foot Doc, Go Gators!

-Dave

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RE: drops while hovering - 2/1/2010 2:22 AM

squawk7700

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I have a similar problem. Here is the senario: Trex 450SE V2/CC PHX45a esc/Align 430XL/2200mah 3s 25C lipo/HS65MG on swash/Futaba 9650 tail/GY401/Spektrum AR7000 w/CC 10a BEC/DX7 Radio.
I only do sport flying, no 3D. All was fine until one day I was not able to bring to a hover. RPM kept cutting back. Had to make major throttle changes on radio from liniar to 0/45/75/95/100. Now I get it to hover and then the RPM drops out. Have to make quick & drastic changes with the throttle stick to maintain a hover but whatever I maintain in this fashion only lasts seconds before another RPM drop.
In an attempt to find the problem I went through the process of elimination. Changed motor, changed esc, changed battery and changed receiver but the problem continues. So the only thing I haven't done was try another radio. My radio works fine with another Trex 450 and an airplane.

Well, what's the verdict? I ran out of idea's and I'm not an electrical engineer.

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RE: drops while hovering - 2/1/2010 12:12 PM

mnc

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if it is a quick cut in power like a glitch it could be a static discharge,you can spray the belt with silicon spray to see if it helps

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RE: drops while hovering - 2/1/2010 7:40 PM

squawk7700

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Thanks for suggestion but I bought some silicone spray and sprayed the belt. Problem still present. ?????
Now I'm having trouble getting it off the ground.

< Message edited by squawk7700 -- 2/1/2010 9:26 PM >

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RE: drops while hovering - 2/1/2010 10:14 PM

mnc

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I dont know what to suggest now you have changed everything. what about settings in your esc like govenor mode or brake or timing

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RE: drops while hovering - 2/1/2010 10:36 PM

dknovick

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quote:

ORIGINAL: squawk7700

IChanged motor, changed esc, changed battery and changed receiver but the problem continues. So the only thing I haven't done was try another radio. My radio works fine with another Trex 450 and an airplane.

Is it possible to change parts between these two birds?

-Dave

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RE: drops while hovering - 2/2/2010 1:49 AM

jfast

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well we fixed our problem, found 2 issues not sure which one fixed the issue of the dropping while hovering, i found my fly bar was slightly bent, also noticed that my esc was set to gov. mode and high timing ,

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RE: drops while hovering - 2/2/2010 2:08 AM

squawk7700

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I really don't want to move stuff between my two Trex's because one is in a fuse with some different electrics. Checked the esc (which I don't use gov mode). In fact as mentioned, I replaced the esc and reprogramed it for the heli. Flybar is new along with the head and rotor system. Thinking of going into my LHS and ask them cause I am baffled. I even tried copying all my settings into another channel of my radio. Not sure if the timing is going to do anything but I haven't done anything with that at this point.

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RE: drops while hovering - 2/4/2010 9:57 PM

asianrider

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I have the same problem with my T-rex 450. I found the battery is bad, or insufficient discharge. IT shut off the receiver, and the heli just fall straigth to the ground. You probably notice the tail start swaging before the receiver shut off.

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RE: drops while hovering - 2/5/2010 2:43 AM

squawk7700

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asianrider, thanks for the suggestion. I'm not sure if that would be the problem. I've tried three other batteries that I know were good. Taking it to my LHS in the morning.

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RE: drops while hovering - 2/5/2010 6:41 PM

Ybenjulkay2x

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I'm still working on mine also, it drop while in hover, head speed okey, if heli drop i just throttle it up, i check -/+ pitch, they are okey, it's -/+10. servo arm center at mid stick, battery are also okey as i use it on my other heli. i'm using airtronics rds8000 on my 450 rex.

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RE: drops while hovering - 2/5/2010 8:47 PM

squawk7700

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Ybenjulkay,
How long will your heli hover before it drops? How much throttle do you input to get it back to the altitude from where it dropped? Did you mean that your headspeed remained the same when your heli drops or does the headspeed drop too?
Didn't make it the my LHS today, I'll try tomorrow. Meanwhile, I'm thinking about my next alternative. Maybe I didn't spray enough silicone on the tail drive belt, who knows.

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RE: drops while hovering - 2/5/2010 9:50 PM

Ybenjulkay2x

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It hover 5-10 second then it drop and I just add a little throttle. Head speed, too hard to tell coz when i replace the main gear an hr a ago (I went to lhs to get the main gear)as i found some of the teeth on the main gear are round off, after a test fly it hover better that before, i believe it loosing head speed a little on hover due to round off gears. also found some binding on one of the blade grip one side is free when changing pitch, the other one, not realy that free maybe coz of thread lock on the screw where the thrush bearing goes so I just add a little oil in it, what's the best oil I could use for this for less static, right now i use turbine lubricating oil to free it.

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RE: drops while hovering - 2/5/2010 9:54 PM

Ybenjulkay2x

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I edit the other one

quote:

ORIGINAL: Ybenjulkay2x

It hover 5-10 second then it drop and I just add a little throttle. Head speed, too hard to tell the sound of the motor and blade are the same but i realize/found something on the main gear, i replace the main gear an hr a ago (I went to lhs to get the main gear)as i found some of the teeth on the main gear are round off, after a test fly it hover better that before, i believe it loosing head speed a little on hover due to round off gears. also found some binding on one of the blade grip one side is free when changing pitch, the other one, not realy that free maybe coz of thread lock on the screw where the thrush bearing goes so I just add a little oil in it, what's the best oil I could use for this for less static, right now i use turbine lubricating oil to free it.

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RE: drops while hovering - 2/5/2010 10:02 PM

Cleared2Engage

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Are you flying in ground effect when this occurs? That's the only time my 450 will bob up and down while hovering.

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RE: drops while hovering - 2/5/2010 10:32 PM

Ybenjulkay2x

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I'm flying my heli outside parking lot while no cars around calm wind. On the 500 it flies okey , the 450 flies okey now after i replace the main gear and lube the blade grip bearing. I'll test it latter when there is wind also.

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RE: drops while hovering - 2/5/2010 11:49 PM

Cleared2Engage

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I'm talking about how high up off the ground are you flying? Are we talking 1-3 feet (ground effect will do weird things to the heli) or are you shoulder high. How high you hover will have an effect on the helicopters flight.

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RE: drops while hovering - 2/6/2010 12:55 AM

baurwin

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quote:

ORIGINAL: squawk7700

I have a similar problem. Here is the senario: Trex 450SE V2/CC PHX45a esc/Align 430XL/2200mah 3s 25C lipo/HS65MG on swash/Futaba 9650 tail/GY401/Spektrum AR7000 w/CC 10a BEC/DX7 Radio.
I only do sport flying, no 3D. All was fine until one day I was not able to bring to a hover. RPM kept cutting back. Had to make major throttle changes on radio from liniar to 0/45/75/95/100. Now I get it to hover and then the RPM drops out. Have to make quick & drastic changes with the throttle stick to maintain a hover but whatever I maintain in this fashion only lasts seconds before another RPM drop.
In an attempt to find the problem I went through the process of elimination. Changed motor, changed esc, changed battery and changed receiver but the problem continues. So the only thing I haven't done was try another radio. My radio works fine with another Trex 450 and an airplane.

Well, what's the verdict? I ran out of idea's and I'm not an electrical engineer.

this sounds like its in your esc programming, maybe you set up both esc's the same. i had a problem almost identical to this, and after going back and really doing a thorough check on my esc programming and what it was supposed to be, i found the problem. i cant remember exactly what it was. maybe the lvc set to high or something. it does sound like your lvc is kicking in too early, so that is what i would suspect. mine would hover for a very short time, then start losing headspeed. then i couldnt get it off the ground. i would try another batt, same thing. i also had a cc 45a esc. plugged it into the computer and went over all my settings, and like i said, i found the problem and its been good to go ever since. but thats definately where i would look.

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RE: drops while hovering - 2/6/2010 1:07 AM

1320Fastback

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Maybe not the cause but an interesting read http://www.heli-chair.com/aerodynamics_104.html

< Message edited by 1320Fastback -- 2/6/2010 1:54 AM >

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RE: drops while hovering - 2/6/2010 4:14 AM

squawk7700

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I believe now that it's going to be my esc. I tried going back to the older firmware to reprogram my esc and now I can reset my throttle to linear and can start hovering for 5-10 seconds before it drops again. So I'm getting closer to fixing this problem. Hey Baurwin, what is LVC and what did you do to fix your problem?

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RE: drops while hovering - 2/6/2010 4:43 AM

baurwin

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quote:

ORIGINAL: squawk7700

I believe now that it's going to be my esc. I tried going back to the older firmware to reprogram my esc and now I can reset my throttle to linear and can start hovering for 5-10 seconds before it drops again. So I'm getting closer to fixing this problem. Hey Baurwin, what is LVC and what did you do to fix your problem?

ur lvc is ur low voltage cutoff. its when your esc sences that your battery is dropped too low on volts and starts shutting down the motor..ie..dropping the headspeed. if you have the lvc set to high, it will go into lvc very quickly, it needs to be set to low. also, since you have the cc, check your pwm settings. i believe you would want that set around 8. if i recall correctly at 8 and 16 my heli performs well, but over that, and it starts performing poorly. make sure you have no brake, and no gov. mode.

i cant remember for certaing what my problem was, but it sounds exactly the same. it would hover for about 15 sec then i would lose the headspeed and it would come down. it was definately in the esc though. i wanna say it was the lvc setting, but may have been one of the other settings...??

it just sounds like the lvc, so thats where i would look first.

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