couple of questions.....................

[tug29]

hi all,

im all set up and ready to run apart from setting the auto throttle cut out, i have a jr xp662 followed instructions in set up manual for it but it does not seem to move the arm on the carb fully closed (forward???). i looked on raptor technique at throttle set up and its says to set travel adjust at 80% top and bottom which i can do however when i go fully up on t/x with control rod disconnected and then down the rod does not line up. can get it to line up on one end but never both ends. have tried moving the servo arm round but it does not seem to make any difference.

to set up throttle cut out manual says put in -40 trim on t/x then with throtttle less than 1/2 open press cut out button and im assuming here servo should be moved to close the carb preventing fuel. i do not seem to have any movement at all. however when i flick the switch to isolate throttle but allowing collective pitch input, the throttle arm moves forwards but not to the end of its travel.
i think it might be a servo position plus length of control rod but im now chasing my tail.

obviously i do not want to start her up yet as i cannot be 100% sure i will be able to shut the engine off if need to.

my engine is a tt pro39 h (r) to run it in are the settings 2 1/2 turns out for high end and 2 turns out low end.

finally when i do get to start it should the throttle be closed or just open, i dont think it should be at the halfway point or am i wrong.

thanks for any help, as im in kuwait the locals have a completely differant way of thinking as we do and im a bit sceptical as to what they say when they actually do speak..................

[Raptorite]

Hi,

The throttle can be a bit tricky to setup, follow this step by step guide and you should be fine;

1. Make sure the arm on the carb is in the middle (pointing straight down) at half throttle, move the arm backwards and forwards making sure you have equal amounts of movement either side of vertical.

2. With the throttle trim all the way down, atv's set to 100% both ways and the throttle stick in the middle (50% throttle), set the arm on the servo so it too points straight down, if you cant quite get it straight because of the splines on the servo and inside the arm then get it as close to straight as you can, then use the SUB TRIM function in the transmitter to adjust the servo slightly until it is straight.

3. With the silver balls screwed on to both arms in the correct places as detailed in the manual, set the rod length so that the plastic rod ends fit over the balls at both ends precisely and attach the rod to the ball on the carb arm.

4. Move the stick on the transmitter to its lowest point which with the throttle trim right down too should be engine off. Now pull the rod forward towards the front of the heli as far as it will go, then using the low atv on the transmitter adjust the servo arm until the rod end and the ball line up precisely.

5. Move the transmitter stick to the top position (full throttle) and repeat the same process as in step 4 but this time using the high atv to adjust the servo arm until it lines up with the rod precisely.

6. Attach the rod to the servo arm and youre done

Ideally the atv settings you are looking for are somewhere between 80 and 100 % and equal on both sides, if they are both bellow 100% but arent equal then dont worry too much as that is fine too.

Now you should be able to start the engine safely with the throttle stick all the way down and the trim about two thirds of the way up between the bottom and middle points.

Cheers,

Pete.

[tug29]

tricky is a understatement

:?

hi again,

i followed your instructions and even though i understand them, have a few problems. i have throttle trim all the way down -40, i have servo arm vertical with +21 sub trim. i set throttle atv's to 100%. the control rod is 75 mm as per the supplied manual. and the carb arm is dead centre. thats easy bit. control rod lines up with both silver balls keeping carb central and not putting any pressure on the servo arm. i have the balls 10.5 mm from centre of servo and on the bottom hole of the carb arm.

now fun begins.

at low throttle with -100% atv the rod is 1/2 the eye too long to get it to fit the ball i have -126% atv. that is with the carb fully closed.

at high fully open with +100% atv the is 1/2 the eye too short. i do not have enough travel on the servo to get the rod to fit it stops moving at +138%.

i have tried moving the servo arm to differant positions on the servo but the arm is always too long in the closed position and too short in the fully open position. i have a feeling it is something very basic and staring me in the face?????????????????????

how do i find full servo travel between each servo stop so i can ensure the arm is exactly central in relation to servo movement, maybe thats a cause. when im putting in initial inputs to t/x ie trim and atv the r/x is on??????

im using a jr xp662 with a jr770 r/x and jr nes-537 servos.

HELLLLLLLLLLLLLP HAHAHA

cheers Gareth

[Raptorite]

Hi Gareth,

Not to worry, this really isnt that big a deal.

What we need to to is to move the ball further out from the centre on the servo arm, this will give the same position in the centre and more movement either end.

I have uploaded a pic of the throttle linkage of one of my 50's to my gallery, take a look at that. I have measured the distance between the centre of the servo and the middle of the ball link which on this one is 17mm.

The reason this is so different from the manual is there are so many different types of servo, each with their own charactoristics in terms of movement etc.

Hope this helps.

Cheers,

Pete.

[tug29]

thanks again

cheers pete,

moving the ball further out has got it. i have -25 sub trim, +110% atv and -97 atv when closed. i know these are out side the ranges you previously stated but thats the closest its been.

only thing that does not seem to work is the auto throttle close button, when i flick the throttle hold switch it closes the throttle right off, is this normal.

your advice has been great help thanks again

Gareth

[Raptorite]

Hi Gareth,

Good news that youve sorted your throttle, yeah the atv's you mention are fine.

The trottle hold function may well be a setting in the tx somewhere to set the tickover level in hold.

Im not that farmiliar with JR sets to be honest, so all I can suggest is you have a look at the book for throttle hold settings.

I hope this helps.

Cheers,

Pete.