mdeseve

My Feedback: (1)

Thanks Mark,for the glitch it is one servo at a time,i suspect the battery. For the flap,i don't understand because i bind another receiver to try it with only the flap on it and it did the same. But the stange thing is that not only one servo does it but both. Can it be the battery,i use lipo 7.4 pulse tx pack. I have the new spektrum 20 ch receiver with dx18 tx, 2x5000 mha pulse rx lipo 7.4. Powerbox igyro.

thanks

Mike

afterburner

My Feedback: (18)

Have you checked how much current either flap servo is pulling before they shut down?

megafly

Hi guys, do you have anny tips on the CG?
Thanks.

mdeseve

My Feedback: (1)

Hi, i had a answer for my flap servo from jet legend, they said that flap servo have an overload protection on it, after 12 sec they release torque till next command. That scare me because when you put flap you what them to retain their position. Did you encounter problem with your flap servo at all, and can you try appliy some pressure on it to see if they release after 12 sec.
thanks

Mike

afterburner

My Feedback: (18)

Did you check the current? If what JL says is true about the servos, you should be more scared at how much current you might be pulling when they shutoff.

mdeseve

My Feedback: (1)

Hi Marty, i will check the amp they pull.
thanks

mdeseve

My Feedback: (1)

When they pull 0.60 amps they quit.

afterburner

My Feedback: (18)

That's too low to cause them to shutdown after 12 seconds I would think. I may have missed if you posted what brand of servos they are. Do you know what the specs are on them?

mdeseve

My Feedback: (1)

It,s their own servo, spark 40 brusless hv

afterburner

My Feedback: (18)

Is that model number servo only used on the flaps or are they used elsewhere in the plane?

megafly

I will maiden mine soon, can you help with control throws and the neutral position on the elevators?
Thanks.

Mark Vandervelden

Hi Mike
I have experimented with a spare Spark servo I have here and can report the following.
The correct voltage for these servos is 7.4-8.4v with enough amperage available to hold that voltage under load.
On my first try I used a small 5 cell nim pack at 6v were I did manage to get them to "let go"
To do this I had to apply a "considerable" and constant force on the servo arm.
When the force is released they return to there original position.

I must add I can only get them to "let go" with both considerable force and a poor voltage supply.
This is true of any servo when the voltage is below spec.

On a good 8.4v supply I could "not" get these servo to let go evan after several attempts.
Certainly not at the amount of force I am willing to apply which felt far more than would ever be needed in actual use.

For your servos to "let go" or "relax" they must be under at the very least "some" strain were in fact they should be under no strain at all.
Are they ended out on the linkage?

I would check your voltage under load, in the Yak there are at least eight servos on board that have a total potential of producing 320kg of force!

If you are in communication with Spark It might be worth asking if they have a servo programmer "gizmo" you could purchase.
There then might be the option of setting the holding power, end point, direction etc of these servos to better suit your needs.

I for one feel confidant in these servos and now have them in three or four air frames all of which have performed faultlessly.
On both my Yaks, Cougar and large F16 I use twin Jeti 5200ma Lion packs that have the potential to deliver up to 80 amp each!

mdeseve

My Feedback: (1)

Thanks Mark for the info, i wonder if they have a servo programmer like hitec, maybe the overload protection is set too low. When i apply pressure they relax at .050 amps at 7.8 volt.

Mike

Mark Vandervelden

Mike
Have you modified the linkage on the flap and aile to give the servo more advantage over the control surface?
Its not 100% necessary on JL PNP with Spark servos as they are powerful and the surfaces are not that big.
The exception are these Yaks flaps which are huge and sit a long way into the breeze.
I have gone from using less than 50% servo travel to over 100% on my adjusted setups halving the servo effort needed.

"The Yak flaps only need to go down 25-30 degree for take off and "defiantly" no more than 40-45 deg for landing"




Shown here is my 1/5th Yak and my JL Cougar, but I have done this to all my JL PNP airframes

I reduce the servo arm output from 20 mm to 13 mm or whichever brings the output hole flush to the hatch skin.
I then have to open the servo hatches slot to accommodate a std 3 mm clevises.
You then have to put the clevis on the servo arm first and then put the arm on the servo with the clevis already snapped on.
The hatch skin this way prevents the clevis from ever opening up and slipping off, works a treat and looks very neat.

mdeseve

My Feedback: (1)

I will do the mods.

thanks

Mark

megafly

Hi Guys, is factory marked CG good for this jet?

Thanks.

mdeseve

My Feedback: (1)

mdeseve

My Feedback: (1)