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Old Jun 28, 2008, 08:14 PM
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rbinc's Avatar
Californication
Joined Nov 2007
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Quote:
Originally Posted by earletp
Why is it so hard for you to just say "Thanks, I didn't realize Loctite had a product they called a threadlocker for plastics", instead of going into this diatribe to cover your mistake?

No one said CA wouldn't work, again the question was "Do you know of such a product? I'd like to learn more about Loctite for plastic."
Okay Earl. Thank you for pointing out that Loctite markets the same CA that has been known, since its inception, to work in this application. And I apologize that I recommended one use common CA (in my second sentence to the poster) rather than this "Loctite" product.

Regards
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Old Jun 29, 2008, 02:39 AM
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Portland, OR USA
Joined Feb 2008
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You're welcome, I'm glad I could increase your knowledge by showing you a product you didn't previously know existed.

Have a nice evening and happy flying!!
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Old Jun 29, 2008, 05:16 PM
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Pretoria, South Africa
Joined Jun 2008
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Check your spares (especially motors) before fitting !

Hi all.

I'm a complete newbie to R/C and chose the Lama v4 as my entry-point into the hobby. Whilst I'm learning OK and it's given already give me many hours of pleasure, I must say I'm a bit disappointed at the poor design of these helis. The thin plastic tail boom is so weak, mine is already shot to hell, those skids fall out almost every time I fly and the battery arrangement is disgusting. I've already spent a small fortune on "upgrade" parts like Extreme blades and an Ali rotor head just to make it reasonably robust.

As others have already noted, there's just no design margin in these Chinese-engineered helis. Yes, they fly well when everything's going OK, but one small mishap and ... it's off to your LHS. Oh well ... you get what you pay for, I guess. At least the spares are readily available and not too $$$.

On a more specific note, I've just had a "weekend from hell" with my heli. Here's what happened - hopefully my story might help others avoid similar fates!

After about 50 flights, one motor failed in what seemd like a mechanical way. Oh well, I thought, perhaps the heavier Extreme blades contributed and I probably didn't wait long enough between batteries (no design margin, see?). At least the 4-in-1 was OK .. grin and cough up $9 for a new motor.

Now I figured that if one motor went, maybe the other one wasn't far behind, so I bought a pair.

Now I'm sure we've all seen the little 100nF capacitors that go between the motor terminals and the case, and between the two terminals (for electrical noise suppression). Unfortunately I didn't check mine before fitting - the workmanship on one was so poor, BOTH capacitors were effectively shorted by solder blobs (see pic). Result = dead short-circuit between the motor supply wires.

So ... here's a sad, blow-by-blow account of what happened when I fired up for the first time after fitting my 2 brand new motors:

1. As I raised the throttle. the ESC fed voltage to the motors. On the shorted motor, the ESC saw a dead-short and blew the ESC FET in the 4-in-1.
2. Now that the FET was blown, the shorted wires on the motor got full voltage and unlimited current (no design protection, see?) so the offending capacitor leg fused with a pretty little white flame.
3. Now that the short was cleared, the (formerly shorted) motor saw full voltage and whizzed off at full speed, taking the B rotor with it.
4. The heli now saw massive unbalanced torque from the oversped rotor, so spun and fell over, smacking the rotors into the deck. Of course, shutting the throttle down did Nada on the (now un-shorted) motor.
5. The B rotor was still being driven and smacked the deck so hard it broke the lug on the shaft hub before I managed to pull the battery.

So, now I'm facing a FET repair on the 4-in-1 AND a new B rotor hub. Not bad for a night's work, eh ?

Moral of the story - check your spares before you fit them !! Commonsense, really, in the bright light of hindsight ...
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Old Jun 29, 2008, 08:54 PM
AKA Don
bz1mcr's Avatar
United States, MI, Houghton Lake
Joined Dec 2002
7,646 Posts
I agree these heli's do not have a large design safety margin. But that is not because they are poorly designed. They fly better than anything available at any place near the price. They really are quite amazing.

Wow! your experience with the replacement motor is a really sad story. It is unusual to loose a motor after only 50 flights. Mine have at least four times that and are still doing well.

Your pictures and analysis of what happened seem to make complete sense, but since things got so hot is a little hard to besure what those terminals may have looked like before you applied voltage, but if you are convinced the solder blobs were shorting the motor from the start I suggest you contact the supplier and ask for a replacement motor and a 50% break on the other parts damaged. Is the second replacement motor faulty also? If it is and you have never installed it that would strengthen your case.

I had a 180 motor in a small plane that also melted the solder connections. A mounting screws had come loose and started rubbing on the back side of the prop spinner. I kept adding throttle trying to keep the plane flying. By time I gave up and landed I was amazed to find melted solder. I learned to cut throttle very quickly any time motor performance does not seem normal. Also anytime rotor or prop hits are expected.
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Old Jun 29, 2008, 09:45 PM
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United States, MA, Malden
Joined Mar 2008
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Quote:
Originally Posted by ZigBee
Hi all.

I'm a complete newbie to R/C and chose the Lama v4 as my entry-point into the hobby. Whilst I'm learning OK and it's given already give me many hours of pleasure, I must say I'm a bit disappointed at the poor design of these helis. The thin plastic tail boom is so weak, mine is already shot to hell, those skids fall out almost every time I fly and the battery arrangement is disgusting. I've already spent a small fortune on "upgrade" parts like Extreme blades and an Ali rotor head just to make it reasonably robust.

As others have already noted, there's just no design margin in these Chinese-engineered helis. Yes, they fly well when everything's going OK, but one small mishap and ... it's off to your LHS. Oh well ... you get what you pay for, I guess. At least the spares are readily available and not too $$$.

On a more specific note, I've just had a "weekend from hell" with my heli. Here's what happened - hopefully my story might help others avoid similar fates!

After about 50 flights, one motor failed in what seemd like a mechanical way. Oh well, I thought, perhaps the heavier Extreme blades contributed and I probably didn't wait long enough between batteries (no design margin, see?). At least the 4-in-1 was OK .. grin and cough up $9 for a new motor.

Now I figured that if one motor went, maybe the other one wasn't far behind, so I bought a pair.

Now I'm sure we've all seen the little 100nF capacitors that go between the motor terminals and the case, and between the two terminals (for electrical noise suppression). Unfortunately I didn't check mine before fitting - the workmanship on one was so poor, BOTH capacitors were effectively shorted by solder blobs (see pic). Result = dead short-circuit between the motor supply wires.

So ... here's a sad, blow-by-blow account of what happened when I fired up for the first time after fitting my 2 brand new motors:

1. As I raised the throttle. the ESC fed voltage to the motors. On the shorted motor, the ESC saw a dead-short and blew the ESC FET in the 4-in-1.
2. Now that the FET was blown, the shorted wires on the motor got full voltage and unlimited current (no design protection, see?) so the offending capacitor leg fused with a pretty little white flame.
3. Now that the short was cleared, the (formerly shorted) motor saw full voltage and whizzed off at full speed, taking the B rotor with it.
4. The heli now saw massive unbalanced torque from the oversped rotor, so spun and fell over, smacking the rotors into the deck. Of course, shutting the throttle down did Nada on the (now un-shorted) motor.
5. The B rotor was still being driven and smacked the deck so hard it broke the lug on the shaft hub before I managed to pull the battery.

So, now I'm facing a FET repair on the 4-in-1 AND a new B rotor hub. Not bad for a night's work, eh ?

Moral of the story - check your spares before you fit them !! Commonsense, really, in the bright light of hindsight ...
ZigBee, Welcome to the wild world of sports and RCgroups. Understand I'm not being critical. We are all here to help you. #1 very critical to give the motors at least a 20 minute cool down period between flights. Give the batteries the same time before recharging. #2 get some PTC fuse harness connectors (they will save your your 4in1 and motors; thank you again earletp ). I was just checking my battrey log..... Yes I keep a log as to how long I fly and how long my battries need to charge. From your posting (50 flights) you didn't mention cool down period. Sounds like your really pushing her to the limits. I've had my V4 since Jan 08 and motors are still strong as ever (about 5 to 6 hours total run time) according to my logs. I'd like to fly more if I had a second heli Have to take it easy with one heli guy
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Old Jun 29, 2008, 10:12 PM
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Barak1001's Avatar
USA, AL, Hanceville
Joined May 2008
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I haven't kept track of the number of hours on my current motors, but I've flown at least 30 to 40 batteries through them, and they seem to still be working like new. I generally let them cool down for 15 to 20 minutes between flights, so I have to agree that it does make them last longer.

I also agree that PTC fuses are mandatory. Especially having replaced a 4in1 once already because I didn't have them installed.
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Old Jun 30, 2008, 02:27 AM
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Pretoria, South Africa
Joined Jun 2008
17 Posts
Hey bz1mcr (and others)

Thanks for the condolences and input :-).

I guess I should rather have said "they are designed with little margin" ... in designing down to a price, any extra components (like PTCs or a current-limiting circuit) get left out. Our choice as consumers is whether to add them ourselves or pay another (more expensive) manufacturer to put them in as part of the design ...

What I forgot mention is that finding this forum and this (mammoth) thread has been a godsend!

Quote:
Originally Posted by bz1mcr
Your pictures and analysis of what happened seem to make complete sense, but since things got so hot is a little hard to besure what those terminals may have looked like before you applied voltage, but if you are convinced the solder blobs were shorting the motor from the start I suggest you contact the supplier and ask for a replacement motor and a 50% break on the other parts damaged. Is the second replacement motor faulty also? If it is and you have never installed it that would strengthen your case.
bz1mcr - the blobs were on one of the NEW motors, not the old one, so it was stone cold when I first powered it up. Hence I know the blobs were there from new (they still are - it's just that the capacitor leg fused on one side and cleared the short). The motor itself is otherwise fine; and the other new motor is also fine.

I'll certainly try and swing some payback on the spares since it was a manufacture fault for sure. My goose is already cooked ... just warning other folks to look for the same fault :-) !

Thanks for the input on the PTC fuse harness connectors ... I'll check those out !
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Old Jun 30, 2008, 10:54 AM
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Chap1012's Avatar
United States, MA, Malden
Joined Mar 2008
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Quote:
Originally Posted by ZigBee
<snip>

Thanks for the input on the PTC fuse harness connectors ... I'll check those out !
EFlight (EFLH1206) here> https://www.helidirect.com/advanced_...121bd&x=12&y=7

You'll only need a set. From my understanding they re-set after cooling.
Mike
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Old Jun 30, 2008, 03:18 PM
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Ohio
Joined Apr 2008
1,190 Posts
Quote:
Originally Posted by Chap1012
Zoandar, Did a quick google (loctite for plastic) and came up with this
http://www.loctiteproducts.com/produ...ID=17&SubID=40

I also came up with many more hits so, it must be pretty common.
Mike.

This might be the ticket: http://mro2go.com/Merchant2/merchant..._Code=51242540
Loctite 425
Thanks! Kinda pricey, isn't it? But I am sure it would last a long time.
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Old Jun 30, 2008, 03:21 PM
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Ohio
Joined Apr 2008
1,190 Posts
Quote:
Originally Posted by Chap1012
Thanks for the answer on "CA." Did a search on this thread and came up with a bunch of "CA's" I jumped over to rcuniverse and there is a cool search tool and found out it is glue. I just glued the two pieces of CD plastic to my battery holder the other day using elmers Stix-All. A lot of adhesives I was looking at stated "adheres to most plastics" and some stated to just three types of plastic. Stix-All states "adheres to plastic, glass, metals, wood." Also it is "solvent free-no VOCs." Sounded good to me. The real test of course will be after a crash to see how it holds up. Pretty sure I paid $5.49 (something in that area).
Mike
Cool. Keep us posted on how well it sticks under crash conditions.
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Old Jun 30, 2008, 03:37 PM
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Ohio
Joined Apr 2008
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Quote:
Originally Posted by ZigBee
Hi all.

(snip) The thin plastic tail boom is so weak, mine is already shot to hell, those skids fall out almost every time I fly and the battery arrangement is disgusting. I've already spent a small fortune on "upgrade" parts like Extreme blades and an Ali rotor head just to make it reasonably robust.
You might try a Vigilante RC tail boom instead. I like mine, and it holds up better than the stock tail fuselage, and makes the Lama look more like a "big rig".

If you have some spray adhesive handy, such as 3M's # 77, spray some on a q-tip and paint it lightly onto each of the skid leg tops. Once you slide them back in, they "will" be removable, but it will take determination on your part to pull them out. When I was still using training gear on my Lama V4, I literally flew it right off the skids one day because they come apart too easily. This adhesive was my solution.

The battery tray is a PITA, for sure, but you will find that if you stick some velcro on the opposite end of the Lipo, and insert the battery backwards (tail-first) it becomes a LOT more pleasant of a task to install one. I have been doing that for most of my Lama's life so far.

Quote:
As others have already noted, there's just no design margin in these Chinese-engineered helis. Yes, they fly well when everything's going OK, but one small mishap and ... it's off to your LHS.
You have an LHS that actually stocks Esky parts?? You are very lucky!! Where are you? I got tired of looking here in North Central Ohio. Never found one within an hour's drive from here. I have to order everything online.
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Old Jul 01, 2008, 02:20 AM
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Pretoria, South Africa
Joined Jun 2008
17 Posts
Quote:
Originally Posted by Zoandar
You might try a Vigilante RC tail boom instead. I like mine, and it holds up better than the stock tail fuselage, and makes the Lama look more like a "big rig".
Thanks - I checked those out at http://www.vigilante-rc.com/
Little pricey, but very nice !

Quote:
Originally Posted by Zoandar
If you have some spray adhesive handy, such as 3M's # 77, spray some on a q-tip and paint it lightly onto each of the skid leg tops .... This adhesive was my solution.
Yeah, I find if I fly with a set of training wheels (spheres) hung onto the skids, then a tighter fit is an absolute must. I've been doing something similar to your solution with nail varnish, as suggested at:
http://blog.ifrance.com/lamav4
Your 3M adhesive sounds like a great solution, too - thanks!

Quote:
Originally Posted by Zoandar
The battery tray ... if you stick some velcro on the opposite end of the Lipo, and insert the battery backwards (tail-first) it becomes a LOT more pleasant of a task to install one.
Thanks - will give that a try.

Quote:
Originally Posted by Zoandar
You have an LHS that actually stocks Esky parts?? You are very lucky!! Where are you?
Uh ... Southern tip of Africa - drop by some time !
Yep, I guess I am lucky, my local LHS is 3miles up the road and has a full range of spares
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Old Jul 01, 2008, 10:42 AM
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Hi guys, I too am new this whole world of rc helicopters having mainly been into rc cars and buggies for years. Whilst on holiday in singapore i bought a esky lama v4 and brought it back to australia. Well i had no idea how much fun these things are, im totally hooked on them. i think i have picked up the skills quite quickly having flown it at my local park a few times.

I just have one problem and that seems to be a common one with the v4, i cant seem to get it to move forward that much. It seems to me that it just needs some weight adjusted to the front. the first thing that came to mind is the battery in the craddle. Has anybody removed the tab holding the battery in place so that the battery can slide a bit further to the front? Also my 4 in 1 unit has been off center from day one, is anybody elses like this?

cheers
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Old Jul 01, 2008, 12:01 PM
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United States, MA, Malden
Joined Mar 2008
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I use the heavy duty skids (not shown here) with my elastic band trick. Elastic bands serve two purposes. They keep the skids together snuggly and also makes for nice mini shock absorbers on those nasty bellie flops. Yes, they have saved my undercarriage (canopy/battery holder) several times. They don't look great...but serves the purpose.


As far as using the "training wheels"...It's best to start right out without them in a large area. I bought some but never put them on. It would be like trying to learn to fly all over again.
Mike
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Old Jul 01, 2008, 12:04 PM
Epilepsy Awareness
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United States, MA, Malden
Joined Mar 2008
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Dang nabbit...I did it again It was suppose to be a link to picture. Sorry folks
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