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Apr 08, 2007, 01:06 PM
Thread OP
Question

how to cut engine power?


hi,

I got mine easystar and graupner mx-12 remote control (same as JR xp6102) and have few questions. I read manual and there is a lot info how to program various stuff but not how to start and stop plane.

First day I spent many hours finding out how to start engine !
I desoldered engine to try it from battery - worked. Then suddenly playing with control it started. Had to keep gear at 0 level for few seconds. Now I cant find way how to cut engine power.
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Apr 08, 2007, 01:13 PM
You may need to adjust the "ATV" or "EPA" to the radio's maximum/minimum on the throttle channel with some ESC's.

Also, JR's throttle channel is typically reversed from Futaba's... if the ESC expects a Futaba, then 0 stick on your JR would be full throttle and full forward stick would be off. That would mean you need to reverse the "servo direction" in the radio programming.
Apr 08, 2007, 01:19 PM
Thread OP
Quote:
Originally Posted by fhhuber506771
You may need to adjust the "ATV" or "EPA" to the radio's maximum/minimum on the throttle channel with some ESC's.


Quote:
Originally Posted by fhhuber506771
Also, JR's throttle channel is typically reversed from Futaba's... if the ESC expects a Futaba, then 0 stick on your JR would be full throttle and full forward stick would be off. That would mean you need to reverse the "servo direction" in the radio programming.
It works ok, full stick forward is full power. To start (0 position) I pull it to mysqlf for few secs. Problem is that I can't find way to stop engine - only to hold stick at 0 position but after I release motor starts spinning again. I have to hold stick and with other hand open my plane and disconnect battery

mx-12 has button "throttle cut" but it stops engine while you hold button down - release and it spins again
Apr 08, 2007, 01:26 PM
I don't use JR transmitters, so am unfamiliar with the programming menu.

Find a way to set the throttle for 120% "servo travel" That should give you the ability to bring the throttle low enough using the stick to shut off the motor.

Should be covered in the radio's manual.
Apr 08, 2007, 04:16 PM
Registered User
Try moving the throttle trim down.
Apr 08, 2007, 04:25 PM
Quote:
Originally Posted by tola555
Problem is that I can't find way to stop engine - only to hold stick at 0 position but after I release motor starts spinning again. I have to hold stick and with other hand open my plane and disconnect battery
Are you saying that your throttle stick is springloaded to return to the center? That's very unusual. Most radios sold in the English-speaking world are what's called "Mode 2" setup, which has the throttle on the left stick, and no spring action on that control channel.
Apr 08, 2007, 06:25 PM
Oldie but goodie
Popsflyer's Avatar
Is the ESC plugged into the correct channel? Futaba and Hitec use ch3 for throttle, Airtronics and JR are different.

You might also have the throttle channel reversed (TX setting) and your ESC is looking for full stick as part of the set-up routine (I have one like this).
Apr 09, 2007, 01:01 AM
Thread OP
Quote:
Originally Posted by ratb
Are you saying that your throttle stick is springloaded to return to the center?
Yes that is exactly what Im saying. Left stick is rudder and elevator. Right is throttle and ailerons. And both move to center if released. So if released throttle goes half way "up" and motor starts spinning again.
mx-12 is programmable, so I believe I can say it that center is 0 but then I will have short way of stick to control throttle. There should be button to switch motor off.
Last edited by tola555; Apr 09, 2007 at 01:10 AM.
Apr 09, 2007, 01:42 AM
Hmmm... right stick has spring loaded throttle.. and left stick does or does not have a spring on the elevator?

Sounds to me like you might have a "mode II" radio trying to use it in "mode I"

To change that, you take the battery out and open the back of the transmitter (4 to 7 screws.)

You'll find the spring loads on the sticks and a tension leaf on the left stick. (assuming left has the elevator stay in place when you let go)

You can remove the spring which is centering the throttle and move it to the left stick, also move the tension leaf from left to right. The 2 sticks are mirror images. Takes about 5 min if you know what you are doing... shouldn't take much longer your first time.

The radio manual will tell how to adjust the stick spring centering stiffness. This is just carrying that a step further.

Someone who has a similar JR radio could take pictures and draw arrows to what needs to be moved.
Apr 09, 2007, 02:00 AM
Thread OP
Quote:
Originally Posted by fhhuber506771
Hmmm... right stick has spring loaded throttle.. and left stick does or does not have a spring on the elevator?

Sounds to me like you might have a "mode II" radio trying to use it in "mode I"

Both sticks have springs in both directions - up/down and left/right.
And it has few buttons like throttle cut and throttle hold. I would like if I push once a button then engine stops. For starting I hold stick in 0 position for few secs. That would be nice but I can't find way to do that. Then I could simply turn plane off for short time and would not need to open plane and push switches and cut wires.

http://www.jrradios.com/ProdInfo/Fil...644-manual.pdf

simply said I need start-stop pushbutton
Last edited by tola555; Apr 09, 2007 at 03:16 AM.
Apr 09, 2007, 03:18 PM
its improper to have the spring centering on the throttle.

On page 14 of the manual it describes "control stick tension adjustment"

Find the spring that applys tension to the throttle stick. Use a pair of needle nosed pliers to get hold of the spring and unhook it. Remove that from the radio. and try operating your throttle. You'll like it a lot better.

The stik may be VERY easy to move. Some radio gimbals are free enough that the throttle lever would flop as you point ther transmitter up and down when you just remove that spring.

There is a way to install a "leaf" to apply tension to a piece of the gimbal to keep the stick from flopping. Its just a thin piece of springy steel appx 1/4 inch (6 to 6.5 mm) by about 1.5 inches (about 30 mm) with a couple of holes drilled. One would engage a molded in peg in the gimbal, the other is for a retaining screw.

I have never heard of a radio shipping with both sticks having dual axis centering springs installed. All the 4+ channel radios I have seen have had one stick that had the throttle use a ratcheting or smooth slipping version of that leaf.
Apr 09, 2007, 11:25 PM
Oldie but goodie
Popsflyer's Avatar
Page 6 of the JR manual states that the throttle stick is ratcheted in the Airplane version. Is it possible that Graupner has modified radio into a "Glider" version, thus the stick centering on all 4 axis?

If so, removing the spring on the stick will not fix the problem as throttle control is 0-100% and the other sticks are normally 100-0-100, unless the software can reprogram the stick function.
Last edited by Popsracer; Apr 09, 2007 at 11:31 PM.
Apr 09, 2007, 11:55 PM
Plug a servo into the "throttle channel" on a glider radio... Test its range of travel from stop to stop of the stick

Plug that same servo into any other channel and repeat the travel check.

If there's more than 5% difference (and the ATV hasn't been set off of 100% or endpoints set) then ship ther radio in for service. Its broke.

They may call the throttle travel 0-100% and elevator -100, 0, +100 %... but its still the same range
Apr 10, 2007, 02:02 AM
Registered User
Quote:
Originally Posted by Popsracer
... If so, removing the spring on the stick will not fix the problem as throttle control is 0-100% and the other sticks are normally 100-0-100, unless the software can reprogram the stick function.
I think you'll find that all the sticks are 0-100%, irrespective of whether or not they self-center. When our servos are centered, they're actually at the 50% (or thereabouts) position.
Apr 10, 2007, 04:24 AM
old aussie
My 2 cents you must have a ratchet set up un throtle control so you can set throttle and leave it in a semi set position to consentrate on trying to keep the thing flying.If it was me i would go back to where you got it and ask them if this is normal for the JR xp I think you got a dud
good luck. Russ


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