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Advantage Hobby . Revolution Models . CarbonXtreme

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e-Quick Of Japan EP-8/10/16/18 > Low Headspeed
 
 
synchro505
Senior Heliman
Location: Topanga, CA

Hello All,

When flying my QJ8 with about a 95% throttle curve on my 9CHP across the board I am getting just over 1000rpm headspeed. Do you think my lipos are failing?

more of my setup:

Mega 16/25/4

CC 45HV
Auto Lipo
Soft Cutoff
Brake-off
Throttle Type-Gov.
Soft Start-Soft
Motor Timing-Standard Adv.
Current Limiting-Off
PWM Rate-13khz

Two maxamps 3S1P 2100 lipos in series
UBEC (35v)

What do you think?
03-01-2006 Over year old.
 
 
Henry
Veteran
Location: Bristol, TN

Yes!
03-01-2006 Over year old.
HOMEPAGE  
 
 
synchro505
Senior Heliman
Location: Topanga, CA

It's really strange. A lipo should be a lipo, right? MaxAmps packs seem really well made. I've read that the sources for the lipo cells themselves are essentially the same and made down the street from each other. But Thunder Power packs seem to perform better and last longer. I can't figure out why. But then, I've never built a pack.
03-01-2006 Over year old.
 
 
Henry
Veteran
Location: Bristol, TN

You got me by the short hairs on that one! My opinion is that charging and cycling are very important to LiPo life. Only once have I over discharged a pack. I was able to revive it by charging each of the 4 cells individually but what a pain in the a@@. It took several hours! Now, if I hear the rpm drop, I drop the heli and change batteries imediately!!
03-01-2006 Over year old.
HOMEPAGE  
 
 
Arief
Heliman
Location: Adelaide, AUSTRALIA

synchro,

I think you may be pulling too many amps from the lipo. Normally would need 3s2P, that way it can handle more amps- 42A continous.
Not sure what the QJ-8 will drain in normal flight though.
03-01-2006 Over year old.
 
 
AnnihilaT
Key Veteran
Location: The Netherlands Force: The Dark Side

Synchro,

I need some more info to help you.

First off how do you know your headspeed is 1000? What did you use to tach it? I suspect if you are using an optical tach that your headspeed is actually double that. If your headspeed was really only 1000 you could not fly. You couldnt even hover.

What is your flight time?
What pinion are you running?

Secondly 2 3S1P i a series is 6S1P and is plenty for the EP8. You can get more power on more cells but this is plenty for sport and light 3D.

Quote 
A lipo should be a lipo, right?


Wrong again... there are more differences than i have time to list however you should not be doing anything running 2 maxams in a series that would be harming them unless you are running them until your esc starts low voltage cutoff. DONT do this. time your flights and end them at the first sign of RPM sag. the SLIGHTEST sign.





A day without sunshine is like, well, night.
03-01-2006 Over year old.
HOMEPAGE  
 
 
synchro505
Senior Heliman
Location: Topanga, CA

I am using a SkyTach optical tachometer. When I set the range above 1000rpm, I see 4 blades. When I slow it down to 1000, it goes back to two blades and stops spinning (or moving). I couldn't believe it. I've used this device on my Logo 10 and compared my findings with a guy who has a Logo 14. We both got the same readings but that was on a Logo 14. I will try testing the headspeed again.

I am getting about 8 minutes flight time. My timer was set for 10 min. But now it is set for 8 min. Because after 8 min., the sound of the heli started to drop a little. So I landed right away.

I am using the 9T pinion.
03-01-2006 Over year old.
 
 
synchro505
Senior Heliman
Location: Topanga, CA

You were right Anni. I was reading the tach wrong. The headspeed starts off at 2000rpm when spooled up on the ground with a freshly charged pair of maxamps 3S packs. But when you try to lift off the headspeed drops to about 1700. From the sound of it in flight, it drops even lower when climbing. I think these packs have seen better days. So I guess I'll start lookin' for some narrow 4S packs...
03-02-2006 Over year old.
 
 
romaink
Heliman
Location: Columbia, SC USA

Low Headspeed

With my EP8 I am running Mega 16/25/4 6S1P9 (two ThunderPower 15C 2100mAh packs in series). Headspeed with an 8T pinion is just under 1800 rpm. As measured with a DPR50, average current draw hovering is about 8A with a max of 12A. I can fly for about 8 minutes using about 1000mAh from the batteries. I have three pairs of the TP 2100s and all give the same result. They are all fairly new. Who knows how long they will hold up.

Richard
03-02-2006 Over year old.
 
 
Heli_J
Senior Heliman
Location: Kannapolis, NC - USA

agree, sounds like one cell is going to the bad...or totally bad....

QUESTION:

I run ax30-10l / quark33 and 2 2100 3s packs....Oh, 17t pinion.....

I get 12 "solid" minuits hover and best headspeed measured is about 1800....

only hovering now and when i goose it, it shots up...

does this sound good to all?

---> Blade CP, T-Rex, MX-400, QJ-8, QJ-16 No Gass, only Electric!
03-02-2006 Over year old.
 
 
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e-Quick Of Japan EP-8/10/16/18 > Low Headspeed
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