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HelicopterBeginners Corner › Planned starter kit, am I on the right track?
01-12-2011 11:23 PM  7 years agoPost 21
Gamb

rrApprentice

Belle Mead, NJ USA

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I don't own a DX7, so can't comment on your particuar setup, but check the setup again. Try the "default" setup for the SR 120. Make sure all the switches are in the "down" position. One of the switches may be set up to switch the gyro from "normal" mode to "heading hold" mode, and this may account for the behavior.

I am not familiar with the SR 120, but is there a gyro sensitivity adjustment on the 5:1 unit? It is unlikely that it got changed during the crash, but worth looking into.

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01-16-2011 06:15 AM  7 years agoPost 22
MasterBlaster

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Murrieta, CA.

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my son in law has a sr and he had the same problem. it was the gyro. it would turn real fast one way and really non responsive the other. after some real minor tweaks to the gyro it works fine.

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02-05-2011 12:49 AM  6 years agoPost 23
MpVpRb

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Burbank, CA

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Get a DX7.

Phoenix sim...good.

120sr...good.

Then, when you wanna do it for real..Trex 600.(preferably with an instructor)

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02-05-2011 02:56 AM  6 years agoPost 24
George Colby

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Greentown,Pa

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Hi,

I am going the same route as you with a 120 SR. I use a 7c Futaba radio, a very capable radio for helis. I would send back the Sr120. Stick with the sim and then apply what you learned to the Blade.
I've been flying planes now for 2 years and it's alot easier to fly then helis. But helis are alot more interesting then fixed wing flying.

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03-15-2011 08:42 PM  6 years agoPost 25
beetree

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Boston

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Hi all,

I haven't updated you guys in a while on the progress I'm making. So the issue with the SR 120 (as shown in the video above) was simply a setting in the DX7. I don't know which setting but I basically reset the DX7 back to original settings and it suddenly worked.

Anyway, I've bought a T-rex 500 now. It took me ~20 hours to build it. I'm probably slow but it was great fun. It's fly-barless. I flew it the first time today and it was pretty stable. I was kinda scared so I didn't do any acrobatic stuff. Eventually I broke the tail glass fiber stabilizer thing so now I gotta buy a new one of those. But hey, that's not too bad for the first flight, huh?

Anyway, I have a question regarding the T-rex 500 about the tail rotor. When I fly my SR-120 and control the tail rotor it always goes back to center. That is, if I release the control of the tail rotor the tail rotor goes back to keeping the helicopter stable facing straight forward. On the T-rex though if I release the control of the tail rotor the tail rotor stays at the same angle (e.g. it doesn't go back to neutral angle) which makes the heli continue to rotate. Is this how T-rex's work? In terms of flying the heli this makes it very different to flying the SR-120 since I continuously need to fine tune the tail rotor as I fly it.

Is there any way of making the T-rex tail rotor behave exactly like the SR-120? That is, to make the T-rex tail rotor automatically go back to neutral angle when I release the tail rotor control on my DX7?

Thanks a lot guys for helping me through my RC-heli adventures!

Regards,
Johan

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03-16-2011 05:22 AM  6 years agoPost 26
MikeM

rrApprentice

Austin, Texas - USA

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If your gyro/tail is not holding where you put it then it's not set up properly, assuming you have it in heading hold mode. Even in rate mode it shouldn't behave as you describe.

Did you follow procedure in setting up the tail & gyro? How bout the head?

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03-29-2011 08:39 PM  6 years agoPost 27
beetree

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Boston

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Hi everyone!

I'm back here again, which usually means I'm having problems

I've been flying without any crash for 10-20 battery recharges and I'm enjoying it A LOT. For the last 5 flights I've been pushing the heli more and more in terms of the throttle curve and I'm now running at 100-90-100 as a preparation for eventually going inverted for the first time.

Today I was running it at 100-90-100 and pushing it even more doing fairly acrobatic stuff. Five minutes into the flight (battery usually lasts ~10 minutes) the helicopter caught fire while in the air. It started with some fumes and the motor loosing power. I immediately hit throttle hold and glided it down and landed it. When it landed it was in flames but the flames stopped within the next minute.

It seems that the fire started with the speed controller and that it didn't spread to any other parts of the heli so I think that it is only the speed controller that is damaged.

Has any of you had any experiences with speed controllers catching fires? Is it too much to go 100-90-100 and push the heli for 5 minutes uninterrupted flying?

Thanks a lot for your continued advice!

Best regards,
Johan

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03-29-2011 08:48 PM  6 years agoPost 28
Wingman77

rrProfessor

Pulaski Tennessee

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Is it too much to go 100-90-100 and push the heli for 5 minutes uninterrupted flying?
no, if anything that is the best thing you can do for a speed control. I would say you have a defective unit. also check all your motor wires and make sure that none of those could have shorted out.

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03-29-2011 11:07 PM  6 years agoPost 29
MikeM

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Austin, Texas - USA

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Which speed controller?

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03-30-2011 05:13 AM  6 years agoPost 30
beetree

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Boston

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Oh, I didn't know there were more then one. I mean "the box" that I connect the battery to, and from which there are three thick wires that I connect directly to the motor. Then there are also thinner wires going to the 3G unit.

/Johan

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03-31-2011 01:31 AM  6 years agoPost 31
Newbe Guy

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Phoenix, AZ

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I think he meant which model ESC? There is only "one" per heli. If you give more detailed info what batts speed controller motor etc.. Then more experienced guys than ME can tell you if the setup was wrong OR if it is/was defective.

I dont know but they would.

Blade mSR / Trex 450se V2 - AMA#965156

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04-01-2011 03:06 PM  6 years agoPost 32
SplinteredBird

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Leesville, LA

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Knowing which batteries would help a lot. Same with the ESC. However I have a feeling you're running the stock align ESC. Depending on what size batteries you are running, I would bet that is what caused it. A semi-educated guess from what you said. Most 5000mah LiPo's should only last about 6-7min of very, very mild flight before you should land and re-charge. LiPo's should NEVER be fully discharged. I could be mistaken, but I remember hearing that the most you should ever take out of your lipo is about 20-30% of it's charge. The smarter and more experianced folks can help clarify this.

The reason I say that it might have been your battery is because lipo fires from all the videos I've seen burn out rather quickly. They burn a HUGE flame, almost explosive, then go out unless other things have caught fire as well. The other possibility is if you were flying them until dead, the massive changes to resistance and other things could have caused the ESC more work making it heat up to the point of the caps and other components catching fire.

Again, I could be wrong, but from what I've read and seen, your average Trex500 max battery size is usually 6S 5000mah. I know some run 10S and such but they run higher end ESC's and stuff than what most beginners would run. That said, in normal mode, easy hovering and flying 6-7min. In idle up with a curve like you said, 4:30-5:00min should be about right.

This of course depends a LOT on your setup of equipment. I.E. ESC, Motor, Pinion size, Maingear size, etc.

If you could post all that info, the smarter people than I could definatly help you out a lot.

Here is a video for an example of a lipo fire.
http://www.youtube.com/watch?v=YCWdnjLqVWw

Granted they did it (on purpose) by over charging/incorrectly charging the lipo, but I've heard of it happening other ways too.

Good luck and hope you get back in the air soon.

I love my flying lawn mowers!
AMA#: 943206
450Pro, 550FBL, 600N

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04-01-2011 07:04 PM  6 years agoPost 33
beetree

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Boston

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Hi,

So, the parts are:

Speed controller: RCE-BL70G Brushless ESC
Motor: 500M Brushless Motor
Battery used: 6S1P, 2500mAh, 25C, 62.5Amp (50C/125amp Burst). It doesn't say, but I'm pretty sure it's LiPo

All parts are the standard part that came with the heli when I bought it (trex 500 ESP 3G flybarless).

The fire didn't look like the fire in the video and the battery is intact. The fire had a purple flame that lasted for maybe 30 seconds.

I'm thinking about going up to a 6S 5000mAh 40C battery to increase my flight time. Is this a too strong battery for my heli?

Also, is the 100-90-100 setting too tough for the speed controller? Should I stick with something like 80-70-80?

Lastly, should I try building some kind of pad for the speed controller so that it gets more cooling? Right now it's simply mounted on the outside as instructed in the manual?

I've sent the parts to Align USA now, and when I called them they said that they would replace it.

Thanks...

/Johan

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04-01-2011 08:42 PM  6 years agoPost 34
SplinteredBird

rrApprentice

Leesville, LA

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Everything looks ok to me and it does look like you got a bum ESC. However you might want to triple check gear-mesh betweein the pinion and main gear as well as decrease your flight times. 10min even on a 5000mah is way too much being pulled out. If you tried 10min on that 2500mah I'm sure it's on it's way out as well.

The 6S 5000mah is fine for the 500. A number of folks I know run those as well. I wouldn't recomend anything much larger though.

Average flight times with that throttle curve imo should be kept to only about 5min or so. The best way to judge how long you can fly though is to fully charge the pack, fly for a short time (4 and a half min or so) then charge it again. When you charge it though, look at how many mah you are putting back in. This is where the 20-30% rules comes in. You don't want to be putting in more than the 20-20% of the total mah of the pack.

A crude example of this.

5000mah pack 20% would be about 1000mah. So if you are putting much more than 1000mah back in you're using a bit too much. I know it doesn't seem like a lot, however depending on how you're flying, headspeeds, and workload on the motor 1000mah can still be around 5-6min flight.

Now after a 5min flight if you only put back say, 850mah (using the crude example above as reference) then you could try to add about 15-20sec, and re-charge. read the mah you put back, and then rinse and repeat. On the flipside however, if after a 5min flight you put back in 2000mah, you'd have to decrease the flight time to bring it down.

I hope all of that makes sense as I'm not the best at explaining things. As for how to time your flight, your radio should have a built in timer that you can set.

What I do, is as soon as I start to spool up, I start the timer. when it starts to beep at me (usually 30sec left on the timer) I bring the heli back to where I want to land as soon as possible. If I land and still have 20sec left, I'd rather power down and charge. Always better to put in less than more.

Again, I'm sure some others who know a LOT more about this than I will chime in and correct anything that I may have said wrong.

I love my flying lawn mowers!
AMA#: 943206
450Pro, 550FBL, 600N

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04-02-2011 12:59 AM  6 years agoPost 35
MikeM

rrApprentice

Austin, Texas - USA

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Average flight times with that throttle curve imo should be kept to only about 5min or so. The best way to judge how long you can fly though is to fully charge the pack, fly for a short time (4 and a half min or so) then charge it again. When you charge it though, look at how many mah you are putting back in. This is where the 20-30% rules comes in. You don't want to be putting in more than the 20-20% of the total mah of the pack.
I wouldn't go by flight time. You have to fly it 2 minutes, then recharge and see how much you took out. Then base your flight times on that.

Where are you getting 20%-30%? Everything I've ever read says it's safe to use up to 80% of the capacity. I think maybe you read don't go below 20% remaining and got the math backwards, yes? Example;
Another good rule to follow here is the "80% rule". This simply means that you should never discharge a LiPo pack down past 80% of it's capacity to be safe. For example, if you have a 2000 mAh LiPo pack, you should never draw more than 1600 mAh out of the pack (80% x 2000).

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04-02-2011 01:47 PM  6 years agoPost 36
SplinteredBird

rrApprentice

Leesville, LA

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I think you're right. I most likely got the amounts backwards. Also, what you said about 2min, then basing the time off of how much you took out was what I was trying to explain. Thank you for the better explination and the corrections.

I love my flying lawn mowers!
AMA#: 943206
450Pro, 550FBL, 600N

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04-02-2011 03:36 PM  6 years agoPost 37
Band1086

rrElite Veteran

Kennewick, Wa. USA

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I think a 5000 6S is going to make the 500 nose heavy. That's the pack the 550 takes. I would say no more than a 3300 6S or so for the 500. I would have probably recommended a 550 to start with. It's about the size of a .30 glow machine, but with twice the power.

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04-03-2011 06:12 PM  6 years agoPost 38
SplinteredBird

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Leesville, LA

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Yes Band is right. My friend is running 3000mah packs. They were just rather large so I did what one should never do and "assumed" they were 5000mah.

I've been looking at a lot of 5000mah packs since I'll be picking up a 550E FBL soon which is where I think I got confused as well.

I love my flying lawn mowers!
AMA#: 943206
450Pro, 550FBL, 600N

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04-03-2011 08:18 PM  6 years agoPost 39
beetree

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Boston

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Thanks a lot everyone for the help!

I'm so bored now waiting for my new speed controller to come back. I'm assuming that it will take 1-2 weeks. Gah...!

/Johan

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04-03-2011 08:46 PM  6 years agoPost 40
SplinteredBird

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Leesville, LA

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Ouch.. I feel your pain.. Good time to get some sim time in though.

I love my flying lawn mowers!
AMA#: 943206
450Pro, 550FBL, 600N

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HelicopterBeginners Corner › Planned starter kit, am I on the right track?
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