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Old May 30, 2011, 09:27 AM
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Lee ,
nice video !

I Wasnt sure wich one to buy neither , the 5888 , or the F27 , I chose for the 5888 because its smaller and probably more fit to fly in small rooms.I also noticed there are more spare parts available of the 5888 on ebay and they are cheaper ...

Could you please take a look at my previous post ( 3 messages above this one) ?

I'd like to know wath you think about my suggestion of putting a bigger battery in a 5888

jonas
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Old May 30, 2011, 01:12 PM
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oh right and an other question lee ,

in the beginning op this topic you said several times that perfect razer sharp tracking is verry important.

English is not my maturnal language and I don't really understand , do you mean you have to make sure the blades are perfectly horizantally levelled ?
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Old May 30, 2011, 01:12 PM
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I guess I bought one! I was on this site:

http://www.focalprice.com/YE376R/588...l?SSAID=389818

put it in my cart, went to checkout to look for hidden fees, ended up at Paypal with a Thank You screen and a Paypal receipt ! LOL

bob
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Old May 30, 2011, 01:16 PM
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Manual

Does anyone have a link to an English manual?

thx

bob
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Old May 31, 2011, 03:30 AM
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Quote:
Originally Posted by jonas hove View Post
I'd like to know wath you think about my suggestion of putting a bigger battery in a 5888

jonas
It's YOUR heli to do with as you please, and easy enough to do (LIPO slides up).

Reasons not to do it >

1. this heli is already almost TOO heavy, then requiring you to put even more "lifting" load on the poor overworked little motors.

2. it's also almost too nose-heavy, thereby exacerbating the problem.

3. extended flight times will encourage even more "deadly" motor overheating.

4. every time you open the canopy to do internal work, you risk breaking a delicate solder connection, sometimes basically impossible to fix [i.e., I recommend opening it only to change motors, and servos if needed, as the LIPOs seem to outlast everything else!]

L
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Old May 31, 2011, 03:43 AM
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Originally Posted by jonas hove View Post
oh right and an other question lee ,

in the beginning op this topic you said several times that perfect razer sharp tracking is verry important.

English is not my maturnal language and I don't really understand , do you mean you have to make sure the blades are perfectly horizantally levelled ?
The blades are coned upward ("dihedral") when spinning enough to fly.

What you need to look for is an extremely precise match of the leading edges, which should appear as a paper-thin (or thinner!) white line when viewing the spinning "rotor disc" edge-on.

If one calculates the blades' path vertically, one can see that each blade is only several blade-thickness vertically between the paths of the other blade (above and below it).

A microscopic asymmetry of the upper and lower space induces a pressure differential on one blade which then causes an aerodynamic AND mechanical perturbation .... which systemically magnifies and eats up to 40% of the otherwise available power!! It's like driving a car or bike with a bent wheel .... but even worse! (blades are MUCH faster!).

Lee
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Old May 31, 2011, 06:18 AM
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The blades are coned upward ("dihedral") when spinning enough to fly.

What you need to look for is an extremely precise match of the leading edges, which should appear as a paper-thin (or thinner!) white line when viewing the spinning "rotor disc" edge-on.

If one calculates the blades' path vertically, one can see that each blade is only several blade-thickness vertically between the paths of the other blade (above and below it).

A microscopic asymmetry of the upper and lower space induces a pressure differential on one blade which then causes an aerodynamic AND mechanical perturbation .... which systemically magnifies and eats up to 40% of the otherwise available power!! It's like driving a car or bike with a bent wheel .... but even worse! (blades are MUCH faster!).

Lee
allright thanks for the explination , i think i how to do it now

cant wait till it arrives , but i think it will at least take another 14 days or something , I'm from belgium and its comming all the way from Hong kong :P

And I'll see what I'll do with the battery , it kind of depends on how long flight time will be with original battery ... but I do understand that it would put extra stress on the motors wich is a risk ofcourse ....

opening it up won't be a problem though, I already opened up alot of electrical stuff , and i own a 6020 heli wich I have opened a lot of times

I've put an upgrade battery of 210 mah in my 6020 and now it flies perfect for 9 minutes and a half , I already flew it a lot and I havent had any problems with engine failure , but i do now that the 6020 is a lot lighter so the engines have to work less hard than in the 5888 I guess

ohyeah and i guess tracking the blades properly also increases flight times than ?
jonas
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Old Jun 01, 2011, 11:36 AM
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Originally Posted by jonas hove View Post
ohyeah and i guess tracking the blades properly also increases flight times than ?
jonas
Yes
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Old Jun 01, 2011, 12:11 PM
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" .... won't stay up now"

... or not for long, etc.

This is almost always caused by dying motors, and when it happens early in the heli's life-cycle it is often the result of degraded brushes caused by overheating from too-long, uninerrupted, unpaused flts!

The faulty used 5888 I got cheaply from Marcel came with two motors he'd (crudely: wires hanging outside) replaced. Dunno how long & hard he'd used them (he tends to be a bit careless, since as a hobbyist/dealer he has many helis for his own use!), but I definitely used them a lot, esp. sorting out its myriad problems and fine-tuning it (much easier when NEW!).

Finally, as I've been getting shorter & shorter flts., I changed the motors. That usually takes 1.2 - 2 hrs start-to-finish., depending on how lucky I get w/ the soldering & how many other solder connections I manage to destroy in the process. This time it was only one large red LED wire broken off the side of the PCB which I carefully but easily re-soldered.

Now it's got normally "peppy" performance again.


NOTE: it's safer & easier in the long run to simply avoid overheating and thus allow the typical 50 - 70 flts* for new motors in a well-adjusted & unabused 5888.


Lee



*that is "only" ca. 4+ flt-hrs, much less than the 20 hrs that high-quality motor MFRs claim (these are not very high-quality), but remember this is a "heavy duty" application in a very heavy heli (which incidentally allows nice flying fun by adding solidity to its performance!)
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Old Jun 04, 2011, 09:18 AM
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failing performance > LIPO vs motors

After I re-vitalized the used & abused 588-B (above) w/ 2 new motors, i checked the LIPO capacity > pausing for cool-downs, I flew it until ca. 20 sec before auto-shutdown, signalled by the rotor start-up beginning to get suddenly slower.

Result: ca. 95% capacity, equivalent to losing maybe 20 sec of "new" flt. time.

And this LIPO was likely not charged nicely before I got it from Marcel (I always cool in the fridge for 5 min, then let it re-warm for 1 min.).

Confirming: the 5888 likes to eat motors (which are cheap!), not LIPO's! So that's why I put mine on an efficiency & low-heat diet!


Lee
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Old Jun 04, 2011, 09:53 AM
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TUNING vs tracking

I think "precise tracking" is now clear to most, but I'm not so sure about "tuning", which involves but encompasses more than just tracking (+ blade-BALANCING!!!).


1. The pinion gears should mesh w/ almost no resistance when the rotors are hand-rotated in reverse. Slide the pinions up/down to optimise.


2. The spinning upper rotor disc should appear ca. 10% thinner than the lower when viewed edge-on. This is very important for aerodynamic (& thus electric) efficiency, keeping the same relative AoA for upper and lower blades (which are in faster-moving downwash).


3. The free-movement "tip-play" or vertical up/down looseness of the tips of the

upper blades = 4 mm, and that of the

lower blades = 3 mm

[carefully micro-bend alu hinges/plates as necessary; vary to get proper tracking! And always remove main blade bolts when so doing to prevent stripping bolt holes]

This allows the upper rotor to compensate for the improved aerodynamic performance of the lower rotor as it gets into faster = "better" air w/incr. RPM!


4. The upper coning angle should be slightly greater than that of the lower. This reduces unwanted rotor interaction & increases performance (incl. manueverability).


5. Lube everything that moves with high-grade silicon/made-for-plastic! lube. I use "Roco" model-train lube, w/ needle dispenser (German).


6. For aggregate electric & aerodynmic efficiency, when checking motor temps., the alu cladding around right motor should initially be warmer than the left, as it is somewhat shielded from the cooling counterclockwise lower rotor downwash. In a few seconds the alu around the left motor should get warm, followed by the rt. motor being only very slightly warmer than the left > OPTIMAL!

7 Don't crash or bounce your heli! But if/when you do .... recheck ALL blade settings!

[L.E. blade dings can be removed with a micro-drop of CA gel and quick filing > the ding gets filled with the filed material!!]



Lee
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Old Jun 04, 2011, 01:46 PM
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I also noticed that the Lipo's on these kind of mini helicopters are really strong , even when you don't take real care of them you won't hurt them , they can take a lot of abuse.

I've never waited to charge my 3 ch 6020 after a flight and i have really often flown it right after it stopped charging and I have never had any issues with the lipo .

It still flies exactly as long as when I first installed the lipo and I've really flown it A LOT OF TIMES (i have it for one year now).
And it was a really cheap 3 dollar 210mah lipo of ebay .

Besides , If you were to break a lipo , they are really cheap on ebay so nothing to worry about .

My conclusion : You should take care of the motors , but you don't really have to think about the lipo , you can fly it right after charge and you can charge it right after flight , it will not hurt your battery at all.
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Old Jun 05, 2011, 07:46 AM
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Originally Posted by jonas hove View Post
I also noticed that the Lipo's on these kind of mini helicopters are really strong , even when you don't take real care of them you won't hurt them , they can take a lot of abuse.

I've never waited to charge my 3 ch 6020 after a flight and i have really often flown it right after it stopped charging and I have never had any issues with the lipo .

It still flies exactly as long as when I first installed the lipo and I've really flown it A LOT OF TIMES (i have it for one year now).
And it was a really cheap 3 dollar 210mah lipo of ebay .

Besides , If you were to break a lipo , they are really cheap on ebay so nothing to worry about .

My conclusion : You should take care of the motors , but you don't really have to think about the lipo , you can fly it right after charge and you can charge it right after flight , it will not hurt your battery at all.
Sorry, but the evidence speaks against your personal opinion [as a Physicist & Engineer I really always do my utmost to be objective and rely on facts, even if deduced from other evidence] >

The fact that the 5888 stays up for a relatively short time AND can easily get the motors very HOT means that the LIPOs in the 5888 are working quite hard, with above-average current flow. That creates heat, and I have found the 5888 LIPOs to actually get hot when in normal use. What degrades or kills AKKUs, incl. LIPOs, is any! heat, which then "boils off" the necessary electrolyte! Heat is a satistical matter, affecting molecules (some are thereby induced to have more energy and go faster than others), and like radiation dosage, has cumulative effects.

I have carefully measured the normal useage/time-reduced capacity of these and other LIPOs .... and they ALL in fact diminish with use & time!

By allowing them to get warmer than necessary (the charging process creates heat), one is reducing their capacity. Whether a given user notices this -- absent careful measurement -- is quite another matter.


"User Beware ...."


Lee


EDIT: while NiCds can be totally discharged, as scorp below reminded us .... LIPOs are severly damaged when discharged below their minimal useful voltage > that's why there is an auto-cutoff!
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Old Jun 05, 2011, 09:41 AM
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Sorry, but the evidence speaks against your personal opinion [as a Physicist & Engineer I really always do my utmost to be objective and rely on facts, even if deduced from other evidence] >

The fact that the 5888 stays up for a relatively short time AND can easily get the motors very HOT means that the LIPOs in the 5888 are working quite hard, with above-average current flow. That creates heat, and I have found the 5888 LIPOs to actually get hot when in normal use. What degrades or kills AKKUs, incl. LIPOs, is any! heat, which then "boils off" the necessary electrolyte! Heat is a satistical matter, affecting molecules (some are thereby induced to have more energy and go faster than others), and like radiation dosage, has cumulative effects.

I have carefully measured the normal useage/time-reduced capacity of these and other LIPOs .... and they ALL in fact diminish with use & time!

By allowing them to get warmer than necessary (the charging process creates heat), one is reducing their capacity. Whether a given user notices this -- absent careful measurement -- is quite another matter.


"User Beware ...."


Lee
You may be right , but i havent noticed any problem with my batteries so far ... could be that they get hotter in the 5888 though

I'm just saying that the lipo's in these helis aren't really the thing to worry about
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Old Jun 05, 2011, 10:48 AM
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I'm just saying that the lipo's in these helis aren't really the thing to worry about
i disagree, one should worry about lipos cause thats the first thing that will go if you don't take care of it... in addition to heat, discharging them too far will kill them and yes its cheap to replace but for most flyers its always better to avoid messing with soldering and screwing something else on those micro boards.
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