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[me3]

Hi all,

Firstly Happy new year to Everyone 

I am not sure if this is the right place to post this but here goes.......

I have seen and driven real jet boats, I don't know how many are aware but the engines don't have gearboxes. They go straight into the jet drive. Neutral is selected and the bucket drops to face down, where the water is pushed down. I am planning on making a model with a similar set-up to this.

I have attached some drawings as it is easier to show than describe  Is it possible to have the motor so it will never stop rotating, if you get what I mean. If I set the speed controller to go from, say, 10% to 100%. When the throttle on the radio is at neutral the bucket faces down, then when the throttle is pushed forward the bucket lifts up, then when the throttle is set to astern the bucket completely drops, all from the same channel. Is this possible in any way?

Many thanks,

Reece

[black magic racing]

in one word    yes  you would have to "y" lead the servo that will control the bucket and speed controller to work of the same channel.it would just be a case of then setting up the servo with bucket in the right position 

[black magic racing]

it should not be to hard to do

[john44]

I would say it is possible by using a Y lead from your throttle
channel one plug to the esc & one to the bucket servo.
adjust the linkage to suit, as you know jet drive motors
only run 1 way hence the reversing bucket.
The esc works on full stick travel, no neutral position
down being off up being full throttle usually on a ratchet
 (not center sprung).
Why would you want the motor running all the time?
that is a waste of power= less running time.

john

[Leaky Bottom]

You could (if your transmitter is able) have the bucket on a seperate channel mixed thru a programmable mixer in the transmitter with the throttle as the master channel, May well be easier than getting the linkages correct

[nick_75au]

I do believe Action have a little gismo


http://www.componentshop.co.uk/p105-single-stick-steam-engine-waterjet-reverser.html

It still stops the motor at centre stick but for electric this is not a disadvantage

Nick

[Peter]

Check this esc for your simplest solution, assuming that you are not using a brushless motor.

http://www.microgyros.com/reversing_jet_drive_speed_control.html

I have used these in a Graupner Moonraker with jet drives, and the operation is very simple.
Just uses normal forward/reverse stick movement on the Tx, and the esc takes care of the rest.

Peter

[Peter]

Re my previous post, I should have emphasised that with the Tx stick in reverse, the motor drive is still ahead, but with the reversing bucket activated.
It makes control of the jet function as simple as it can be.

Peter

[me3]

Aha, Thank you for the information. I was hoping someone made an ESC to do it all for me  , I don't understand all this mixers and that. I understand where you are coming from about not having the motor running all the time, I think it would add realism, I don't leave the model in neutral much, I am a bit of a speed merchant, hahaha thanks again for the help :)
Reece

[Peter]

Hi me3,
Given your last comments, this esc would be ideal for you.
It makes forward/astern control with jet drive as simple as with a normal prop drive, in that the only control input required by you is to move the Tx stick up/down as required.

1 Moving the Tx stick up controls the motor speed for forward motion.
2 Bringing the Tx stick back to centre reduces the speed to zero.
3 Moving the Tx stick down, fom the centre poin, activates the servo for the reversing bucket.
4 Continuing to move the Tx stick down, increases the motor speed, but still in the forward direction,
    thus providing astern movement via the reversing bucket.

As I said, have used this in a Moonraker, which previously had independent control of motor speed and bucket activation,  and this is a much better and more relaxed method of control.

The set-up is very straightforward, following the supplied procedure notes,  and I experienced no problems.

Peter