rrTV-PHOTO   New HD TV
HOME   rrTV-PHOTO   GALLERIES   MY GALLERY   HELP-FAQ
myHOME PM pmRR MEMBERS 736 ONLINE 19 EVENTS SEARCH REGISTER  START HERE
 
1 page779 viewsPOST REPLY
3D Heli Depot . JR-Spektrum . Gyro Hobbies

.
.
e-Minicopter Joker > Head speed shake with one set of batteries, not there with another.
 
 
kiwidave1
Veteran
Location: Seattle, WA

Hi all, I get a small headspeed shake when using one set of 10s5p batteries but don't when using another brand of batteries. the headspeed is on a governor and stays the same.
Both are 10-12C packs.
Maxi Joker 2
Power Jazz
NHP 800mm

Any idea what could be causing this? All cells on both batteries are in balance.

Thanks!

david

Never underestimate the power of stupid people in large groups.
10-29-2007 Over year old.
HOMEPAGE  
 
 
JohnC
Veteran
Location: East Yorkshire, England

LOL - I think you found yet another hole in the laws of physics Dave

Do they weigh the same ?.
10-29-2007 Over year old.
HOMEPAGE  
 
 
kiwidave1
Veteran
Location: Seattle, WA

I think about the same weight....but I haven't weighed them, I will check their weight when I get home......(EDIT: Weigh difference below.)


{{{Shaking his fist at the heavens}}}

david

Never underestimate the power of stupid people in large groups.
10-29-2007 Over year old.
HOMEPAGE  
 
 
QueeQueg
Senior Heliman
Location: West Texas

Have you actually checked the head speed with a tach.

If you're using the ESC's Gov mode doesn't mean it will be the same head speed.

If the packs voltage under load is different the head speed will be as different well.

And one thing I know about most helis is they can vibrate at one speed and be smooth as silk at another.
10-30-2007 Over year old.
 
 
HawkEyeMedia
Senior Heliman
Location: Fort Worth, Texas

Yeah, with the Jazz ESC in governor mode, if the initial voltage is different between packs, the governed headspeed will be different.

Try this, after a flight when your pack voltage is lower than after a fresh charge, shut everything off, then turn everything on and spool it up, you'll see the new governed headspeed is lower than when starting from a fresh set of packs.

Mark LaBoyteaux
HawkEyeMedia.com
10-30-2007 Over year old.
HOMEPAGE  
 
 
kiwidave1
Veteran
Location: Seattle, WA

I am using a separate governor and also using a SkyTach. so I am sure that the head speed is very close to 1360 if not bang on.

Thanks!

David

Never underestimate the power of stupid people in large groups.
10-30-2007 Over year old.
HOMEPAGE  
 
 
ELOSSAM
Veteran
Location: Es

Very close but not the same can be the cause. There is allways a limit where the heli can start oscilating due to low RPMs. Itīs easy to see if itīs that. Increase the THR curve/line value to give some RPMs more and see if both batteries are now running the heli in the needed range.
10-30-2007 Over year old.
HOMEPAGE  
 
 
rerazor
Elite Veteran
Location: Mich.

Sounds like resonance caused by a slight deviation in head speed and/or weight difference.

Try it without blades etc....
10-30-2007 Over year old.
 
 
kiwidave1
Veteran
Location: Seattle, WA

Thanks for all your help!!

David

Never underestimate the power of stupid people in large groups.
10-30-2007 Over year old.
HOMEPAGE  
 
 
kiwidave1
Veteran
Location: Seattle, WA

Sorry to revive an old thread but I flew today in light gusty (gusting 8-10 MPH) conditions and really noticed this issue. I have the following setup.
Maxi Joker 2 with NHP 800 blades.
CARVEC
32-4, powerjazz, and these are the two batteries.

Tanic 10s5p 7500mAh and
Common Sense 10s5P 6000mAh

The Tanics weigh 1.6Kg (3.5 pounds) and
The Common Sense weigh 1.9Kg (4.2 Pounds)

Both are 10c (I think) and balanced while charging
The head speed is nuts on at 1360 rpm
CG is very close if not the same.

I get a very small vibration with the common sense batteries but with the Tanic packs I get a full body much larger vibration.

This is really strange to me why I would get this with one pack and not with the other. The only difference I see is the weight.

Any ideas?

Thanks!

David

Never underestimate the power of stupid people in large groups.
11-11-2007 Over year old.
HOMEPAGE  
 
 
d-bledsoe
Veteran
Location: Kirkland WA

Well i would say something is oscillating, and the reason its more noticeable with the tanics is because they are almost a pound lighter.
Now the trick will be figuring out what is causing the oscillation.

I know you crashed a while back and replaced just about everything on the heli, after fixing it was the problem apparent, or did it just start happening?

Maybe one of these weekends we can get together and take a look at it, 2 brains are sometimes better then 1

-Derek
11-11-2007 Over year old.
HOMEPAGE  
 
 
kiwidave1
Veteran
Location: Seattle, WA

Please don't over estimate my brain, I think you could expect no more than 1.5 brains if we got together

I think I will put in another order with FX or Joe and see if I can buy a complete new head for it.

Lets get together sometime and see what we can make of her.

Cheers!

David

Never underestimate the power of stupid people in large groups.
11-11-2007 Over year old.
HOMEPAGE  
 
 
QueeQueg
Senior Heliman
Location: West Texas

Just too see if it's the weight causing the issue, try adding ballast to the lighter pack and see what happens.
11-11-2007 Over year old.
 
 
kiwidave1
Veteran
Location: Seattle, WA

Thanks All!! I have taken off the head and the Maxi just purrs nicely, I reattach the head and I do fell a vib in the body.
I have taken the maxi paddles off (about 35 grams) and put on some raptor 90 black paddles (about 50 grams) and flybar weights I have balanced the head as best I can, I mainly did this cos the maxi was jumping around in 10mph winds, I want her more stable than that. Spun up and still feel the same vib.
I then removed the blade grips and noticed a slight difference in how far off they sit from the head block (.2-.3mm) I changed the o-rings around and one side still sits out further. Cleaned the inside of the head block, played with the o-rings and still the same side is siting out .2-.3mm further than the other. I have to presume that it is due to the milling of the head. Is .2-.3mm difference in the distance of the blade grips to the head going to make a lot of difference, or cause this issue?

Thanks!

David

Never underestimate the power of stupid people in large groups.
11-11-2007 Over year old.
HOMEPAGE  
 
 
d-bledsoe
Veteran
Location: Kirkland WA

Sounds like you may have found your problem. Lets get meetup next weekend and i will bring you my spare head block see if that makes a difference before buying a new one. If it does then its yours!

-Derek
11-11-2007 Over year old.
HOMEPAGE  
 
 
QueeQueg
Senior Heliman
Location: West Texas

If it's a difference in the depth of the damper pockets I'd say you've probably found it.

If that's the case I'm sure that Gerd will replace it for free.
11-11-2007 Over year old.
 
 
Highviz
Senior Heliman
Location: Newbury, Berks, UK

Hi David,

Did you manage to fix this problem - and if so, what did you do?

- Have just found a similar problem with my backup MJ, in that it has a shake when loaded up with camera mount, but appears to be pretty smooth without. The No 1 MJ is silky smooth with the same mount / load below it.

- I'm just starting to check all the usual bits but thought you might be able to give me a short cut.

Thanks

Malcolm
12-29-2007 03:11 PM
HOMEPAGE  
 
 
kiwidave1
Veteran
Location: Seattle, WA

No I haven't fixed it yet. It looks stable enough when I have the camera mount on but shaky with no mount. I hope to try another set of blades in the come week or so as that is the only part that I haven't replaced and see if that fixes it.

Cheers!

David

Never underestimate the power of stupid people in large groups.
12-29-2007 06:37 PM
HOMEPAGE  
 
 
1 page779 viewsPOST REPLY
E-flite . Next D . Fast Lad Performance

.
.
e-Minicopter Joker > Head speed shake with one set of batteries, not there with another.
 PRINT TOPIC Advertisers 

Subscribe to This Topic

Thursday, November 20 - 5:48 pm - Copyright Đ 2000 - 2008 runryder.com | email | link to rr | runryder needs cookie