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Old Mar 30, 2012, 02:07 AM
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Thanks for the reply.

My PCB looks different to yours. Mine does not have white lines printed on it surrounding the different areas and the rectangular silver component on mine has a different code ( c025) stamped into it.

It is really difficult to see exactly where your aerial attaches because of the white silicon they have put around the area plus there are so many other solder points in that area !

My old aerial is indeed 29mm long so whatever I do I'll try to keep it the same length.

Cheers,

Steve
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Old Mar 30, 2012, 05:29 AM
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Soldered the aerial back on so am now good to go !

( Until the next time ! )
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Old Mar 30, 2012, 08:35 AM
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That is where it attaches on all of mine, too. However, some of the early models had the wire entering through the hole from the rear of the PCB, going through the hole covered by what is referred to as a pad in the left photo in the above post #870, and soldered on the front side, as often with contacts through a PCB. Nonetheless, THAT is the antenna connection!

Some that are attached with the wire entering from the front were factory-bent around the outside of the PCB to extend rearward past the cabin.

Lee
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Old Mar 30, 2012, 10:49 AM
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Anyone know a good place to buy replacement batteries for this heli ? Obviously the cheaper the better. I've bought from China before so that is no obstacle.

Will any old 3.7v 180mAh battery do ? I don't think so because I got one that had a code number 502026 that does not seem to charge up fully like the original DS 602025 battery even though it is a 3.7V 180mAh battery. When I install it in the heli it doesn't have enough power to get off the ground.

I presume it also has to have have an overcharge circuit board built in as well.
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Old Apr 02, 2012, 05:10 AM
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Quote:
Originally Posted by gbjbasdw View Post
Anyone know a good place to buy replacement batteries for this heli ? .... I presume it also has to have have an overcharge circuit board built in as well.
Normally one can remove the overcharge-PCB and install it in another LIPO if needed. You can use Google to research the technical characteristics of most batteries, incl. rechargeable "batteries"/AKKUs, such as these LIPOs. B.t.w., most distributers carry the req. G.T. replacement LIPOs.

L
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Old Apr 02, 2012, 05:25 AM
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delighted

UPDATE: that customer-'killed' 5888 that had been factory-shipped to Marcel with disasterous short shafts and which I got to cannibalize for parts .... is now all one could ever ask for in a tiny 4-ch FP heli.

After changing most of the moving parts and carefully adjusting them [incl. delicately filing imperfectly molded plastic hub center-pieces to equalize pitches on both blades, etc.], it just kept getting better & better. So I just kept working on it and further improving it!

Now it is very fast, very easy, very maneuverable AND very stable! And quiet!

Point: with care & parts, any 5888 with a functioning PCB can be improved to whatever level the user is willing to work towards. That work is the 'hobby' part of the "Hobby Grade Flying Performance". And thus it's possible to make a 5888 BETTER than any such heli on the market.

truly
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Old Apr 02, 2012, 08:19 AM
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Found a supplier in China who can supply original GT 5888 batteries.

Got two batteries for £5 delivered which I think is a very good price.

If you need details let me know.
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Old Apr 05, 2012, 07:32 AM
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It IS a good price, comparable to what Marcel charges [he brings them and other heli stuff to a nearby Flea Mkt for me .... but only when he has them].

Good find!

L
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Old Apr 05, 2012, 08:07 AM
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correct rotor adjustment doubled flt. time! [UPDATE]

The optimal 4mm upper/ 3mm lower rotor blade "tip-play" setting is predicated on correct pitch setting for both rotors!*

One of my older & gradually improved 5888s (incl. replacement motors, servos & LIPO) developed the annoying behaviour of significantly yawing left every time I quickly added a lot of power. I dislike having to correct for this with right yaw stick input, so I carefully viewed the ends of the alu plate hinges, with blades still attached but turned "fwd".

I noticed that somehow the upper rotor hinge plates had gotten more pitch [slight positive angle w.r.t. plane orthogonal to rotor shaft] and the lower, less [slight neg. angle].

Removing the small thin inner "adjustment" bolts [larger main outer bolts already locked in place w/CA gel] -- and noting which bolt went with which hole > extremely important to avoid stripping! -- with blades skewed fwd I twisted both alu hub hinge-ends back to neutral.

Problem solved .... plus more than doubled flight times! [heli now flies well up and out of ground effect until a few seconds before auto-cutoff]


Lee

*This combination allows the lower rotor [in upper-rotor accelerated airflow] to visually have ~10& more pitch [relative to us, NOT to the airflow!] than the upper throughout the entire RPM range, but with a bit LESS differential at the top end as the lower rotor jumps into much more efficient higher Rn [the Rn in these low ranges is a particularily non-linear ftn.!].

I am pretty sure that the engineers at G.T. [G.T. calls them designers] are not consciously aware of any of the above. Luckily for me [and any who read my posts] I have a longer, deeper and broader technical background than they do ... which is why I so much appreciate the basic 5888 design!
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Old Apr 07, 2012, 06:26 AM
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that cool "turbine-whine" sound ....

I now discovered that the 5888s make the very high-pitched "turbine-whine" .... when they are:


1. PERFECTLY tracked & tuned, AND importantly

2. each (esp. lower) rotor [when hand-turned in rev. w/heli inverted] shows miniscule, barely perceptible resistance (compared to pinions disengaged).

This requires careful selection of pinion and/or gear combos AND pinion positioning, as I've previously posted!



Lee
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Old Apr 10, 2012, 07:10 AM
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easy wobbling fix

Assuming everything else is carefully adjusted, the blades well-tracked, etc., wobbling [most noticed by fore-aft rocking of the body] is usually caused by a loose upper-rotor link. They simply wear out with use, esp. from untracked rotors!

Even if replaced, most often the new link is still loose! By "loose" I mean: when the upper blades are held immobile, if the weighted flybar end has more than 5mm [3/16"] up/down free play .... the heli will normally wobble.

Cure: simply lube the ends, remove the "dog-bone" link and use a strong hairdrier to heat each link end, then squeeze it up/down flatter, making it slightly oblate. Use pincette/tweezers, etc., and hold each end thus until cool. Lube, re-install.


Lee
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Old Apr 12, 2012, 06:52 AM
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explanation: SELF-adjusting hub

The upper alu hub-plates & middle plastic hub-pieces slide over each other and also over the lower alu plate .... within the extremely narrow limit allowed by the necessary looseness of the bolts w.r.t. the holes through which they pass [bolts are locked in the lower plate threads, and hopefully moreso by user-applied CA gel!]. I am quite sure that the G.T. engineers/"designers" did NOT consider this and näively assumed everything would be held stable by the bolts.

In any case, the following nice result of their presumed oversight ONLY works when the blades are perfectly tracked [L.E. appear razor-sharp in spinning rotor disc!] and only allowed 4mm upper/ 3mm lower rotor "tip-play". >


If the tip of "blade 1" tries to rise, due to too much up/down "tip-play" looseness and/or too much relative pitch, the top plate [in either rotor!] will be pushed towards the opposite "blade 2", trying to push its tip down. But the rotational inertia [so-called "centrifugal" force, imaginary counterpart to real centripetal force] will try to keeep it level. So the hub itself will tend to tilt away from "blade 1", and both blades will tend to stay tracked!


This actually works, and is a good reason to initially spend time & effort perfectly tracking the rotors!



Lee
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Last edited by xlcrlee; Apr 14, 2012 at 07:40 AM. Reason: moor speling problem
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Old Apr 19, 2012, 08:16 AM
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cool MACRO-trim discovery!

While changing servos on one of my 5888s which has a HUGE servo-throw [travel range, requiring a delicate piloting touch but allowing very high speed and super-tight banked maneuvers], I found that the Tx trim button didn't have enough effect and the new servo was already maxed-out in one direction!

I had previously theorized this, but when I actually tried it ... it worked! >

1. turn on the Rx

2. hold the stick in the OPPOSITE direction you want the trim to go, but not necessarily all the way to the extreme, as the effect is proportional

3. with the stick held in that position, turn on the Tx and wait for it to lock on

4. you'll find out if or how much further macro trim-correction might be required


Lee
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Old Apr 23, 2012, 05:33 AM
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Marcel now has the Nine Eagles Solo Pro 100 3D [SR CP] for 130 bucks [USD/Sfr]. After careful online review, incl. videos, I feel it is not only not worth 3x the cost of his 5888s, but also stupid to buy, as it flies worse IMHO than my "hopped-up" 5888s [in terms of precision and smooth realistic flight]. However the visual impression of speed [in my livingroom] IS similar, esp. since one would have to slow down the Solo Pro 100 in such a small space: my 5888s fly about as fast as my birds can in that airspace .... which IS pushing the [speed-] limit there! [they can fly slow, but often just like to zoom!]

Finally, I find the colors and color-scheme of the Solo Pro to be quite un-aesthetic, as well as the general design. So I stick with my super-5888s ....!


Lee
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Old Apr 25, 2012, 07:04 AM
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cute anti-spiral-dive piloting trick

I'm not sure if this is unique to the 5888, but like many coax's they have a tendency to want to speed up and spin-in during too-fast 15°- 20° banked left circles*. I've carefully adjusted all but one of mine to eliminate this "design-feature"-crashing. That one has significantly more servo throw than normal, and as it is "hopped-up" [= super-tuned!] like the rest of mine and thus way overpowered (vs factory non-set-up) .... it will easily accelerate and nose-spiral in during fast banked left circles.


The "trick" I now discovered is when it starts to self-over-bank and speed up in a left circle, I simply release the right stick (all the way or let it only partially re-center) .... and it self-corrects into its previous stable bank and speed! Then I return the right stick to its initial fwd & left position. During this procedure the heli smoothly flies unperturbed and stable ....!


Lee





*consequent to the 45° counterclockwise/LEFT-offset of the flybar! [vs conventional 90° for helis]
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