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Author Topic: Trim Tabs  (Read 3141 times)

C-3PO

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Trim Tabs
« on: December 18, 2017, 09:33:12 AM »

I have been playing with some ideas with regards to trim tabs.

I understand that you use them to determine your desired attitude.

I have seen conflicting information about how they are used with a planing boat whilst turning - do they get used whilst turning? - specificly are they used to trim the boat in (during) a turn?

Thanks in advance for any information

Regards
C-3PO



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TomHugill

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Re: Trim Tabs
« Reply #1 on: December 18, 2017, 09:52:12 AM »

Yes they do
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RAAArtyGunner

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Re: Trim Tabs
« Reply #2 on: December 18, 2017, 10:03:41 AM »


Do they also help in keeping it running straight such as countering prop torque???
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T33cno

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Re: Trim Tabs
« Reply #3 on: December 18, 2017, 10:40:36 AM »

I was thinking that perhaps there is already an auto gyro device for aircraft that could be adopted. I've seen such items but I'm not familiar with aircraft trimming myself. Also there would be compatibility issues with different TX/RX sets
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T33cno

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Re: Trim Tabs
« Reply #5 on: December 18, 2017, 10:54:38 AM »

https://hobbyking.com/media/file/25238223X497289X56.pdf


I'm thinking along the lines of using the AIL 1 & AIL 2 for the trim tabs?
Rudder for nozzle direction
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McGherkin

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Re: Trim Tabs
« Reply #6 on: December 18, 2017, 12:36:31 PM »

Trim tabs are primarily used for 3 purposes on most boats.


1. For getting up onto the plane.
2. For levelling any listing caused by uneven loading.
3. To change the angle of the boat when driving into heavy seas at an angle.


Since trim tabs are usually manually controlled, they’re mostly just set and left. However some expensive boats these days have automatic trim tabs which can also provide levelling in turns.
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C-3PO

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Re: Trim Tabs
« Reply #7 on: December 18, 2017, 12:40:14 PM »

Hi Andy,

Using one of the sensors would ( or similiar) (should) work well...

https://www.youtube.com/watch?v=eqZgxR6eRjo

Would need a "logic" device e.g. Arduino to interpret sensor data and apply preset rules as to how to apply positioning to each trim tab servo independently

C-3PO
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C-3PO

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Re: Trim Tabs
« Reply #8 on: December 18, 2017, 02:52:43 PM »

ITTS – Intelligent Trim Tab System

Too cold to play outside so I have started to see what could be achieved – here is a the basic evaluation hardware



C-3PO
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T33cno

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Re: Trim Tabs
« Reply #9 on: December 18, 2017, 03:37:11 PM »

Love it  :-))
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bj

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Re: Trim Tabs
« Reply #10 on: December 18, 2017, 04:07:45 PM »

See https://www.ebay.co.uk/itm/TRIM-FLAP-RC-controlled-rc-model-boat-adjustable-nitro-gas-tab-FSRV-FSRO/391008657318?hash=item5b09ee9fa6:g:4DAAAOSwj0NUlyhK


Often used as a pair controlling both straight running and left hand turns by the FSRV fraternity and normally programmed through a Multiplex Tx
Possibly couple with  ITTS – Intelligent Trim Tab System by C-3PO????
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McGherkin

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Re: Trim Tabs
« Reply #11 on: December 18, 2017, 11:21:48 PM »

ITTS – Intelligent Trim Tab System

Too cold to play outside so I have started to see what could be achieved – here is a the basic evaluation hardware



C-3PO

Very cool! I must admit I've toyed with the idea.
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C-3PO

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ITTS - Intelligent Trim Tab System
« Reply #12 on: December 19, 2017, 09:17:29 AM »

See https://www.ebay.co.uk/itm/TRIM-FLAP-RC-controlled-rc-model-boat-adjustable-nitro-gas-tab-FSRV-FSRO/391008657318?hash=item5b09ee9fa6:g:4DAAAOSwj0NUlyhK

Often used as a pair controlling both straight running and left hand turns by the FSRV fraternity and normally programmed through a Multiplex Tx


bj - Nice looking (although expensive) bit of kit - I wonder what range of travel it has?



C-3PO
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C-3PO

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Re: Trim Tabs
« Reply #13 on: December 21, 2017, 09:26:03 PM »

Work in progress...

Video - https://youtu.be/XCulojwAItc



C-3PO
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T33cno

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Re: Trim Tabs
« Reply #14 on: December 21, 2017, 09:29:40 PM »

Very Promising Jonathan  :-))
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C-3PO

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Re: Trim Tabs
« Reply #15 on: December 21, 2017, 10:14:47 PM »

Very Promising Jonathan  :-))

Lets hope so....

The video is just trimming pitch - I now have added "roll" into the equation - really fascinating to watch the servos react to the combination of movement in 2 dimensions...

C-3PO
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T33cno

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Re: Trim Tabs
« Reply #16 on: December 21, 2017, 10:16:45 PM »

Yes I could see that  :-))
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C-3PO

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ITTS - Intelligent Trim Tab System
« Reply #17 on: December 22, 2017, 05:59:10 PM »

Getting more interesting - pitch and roll trim...

Trying to work out what interaction the throttle/rudder would have on the trim tabs - any info much appreicate

Video - https://www.youtube.com/watch?v=J5f6BirD3SM



C-3PO
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derekwarner

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Re: Trim Tabs
« Reply #18 on: December 22, 2017, 10:39:50 PM »

Very interesting C-3PO and truly appears to be a clone to gyroscopic positioning :-)) ...although I am not sure in the concept .............my understanding is that the deployment and control of the stabilizer trim tabs is to negate throttle and rudder adjustments in sea conditions by the use & action/reaction of the stabilizers

Naturally there is a limit to what effect the stabilizers can have on the hydrodynamic performance of the hull in the varying sea state, where dependent of this, the vessel speed may need to be reduced

Further propeller shaft speed in vessels say... as a 5000 to 8000 tonne destroyer powered by Olympus or GE gas Turbines is something that cannot be racked up & down like a lawn mower.......[the scenario being the gas turbine and diesel engine common drive are all computer controlled to balanced {in any variation of COGOG or DODOG} onto a single output shaft to a single propeller shaft

Derek
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C-3PO

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Re: Trim Tabs
« Reply #19 on: December 22, 2017, 11:49:07 PM »

Hi Derek,


This video shows the type of thing I was trying to emulate (I think)


https://m.youtube.com/watch?v=CruJRMOoAAg


It's a subject that I know less than zero about so really exploring what might work.


Started on the easy bit to see what the response time moving the servos might be
 
I think it's possibly worth installing on a test hull to see what happens and if the are any positive benefits


I am not sure if there is are any merits in adding rudder/throttle position into the control algorithm- and if so how they would get used/ what logic could be applied


I have just received some trim tabs as mentioned earlier in the thread so will try to hook them up to the servos


Not sure what the destination with this is - but the journey is fun and I have already learn't some blindingly obvious approaches to deal with a constant stream of sensor data which was not apparent to me previously and will get very useful in future projects


C-3PO



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TomHugill

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Re: Trim Tabs
« Reply #20 on: December 23, 2017, 07:07:04 PM »

Hey C3PO, looks like a fantastic endeavour! Not seen the Arduino used in this way.


For those amongst us of a less technical bent, the straight levelling aspect could be achieved with a submarine pitch controller, however you wouldn't get any other functions that might be included.
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C-3PO

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Re: Trim Tabs
« Reply #21 on: December 23, 2017, 07:50:53 PM »

Him Tom,

Thank you - I have brushless lifeboat that could probably benfit from this but I have a Moonraker that I want to initially try it in   - I need to get mine moving significantly faster than it does right now - I often review some of your video's as my reference point.

The servo movement in the video is overstated but shows the reaction to the movement of the sensor.

I am on the search for any input as to whether to hook up throttle and rudder and how this input might be used in the control algorithm

I do note that some boats seem to deploy full trim tabs to get up to and on planing

I guess I need to get it installed in a boat to see whether this idea actually has legs...

C-3PO
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kinmel

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Re: Trim Tabs
« Reply #22 on: December 23, 2017, 09:09:14 PM »

There is a radio receiver with a built in Gyro and 3 axis accelerometer ..   www.rclife.co.uk/Frsky-RC/Frsky-Receivers/FrSky-S6R-6ch-Receiver


I have no idea how it works, but it suits one of my transmitters.
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TomHugill

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Re: Trim Tabs
« Reply #23 on: December 23, 2017, 10:17:16 PM »

Hey C3PO,


I wouldbe very intrested in how you get on with the moonraker! I have seen moonrakers with adjustable trim tabs on servos. A mod which I  like the idea of as I seem to have to tweak the tabs each time I run mine. Being able to automatically raise the tabs in turns I think could really help stop the nose digging in and flipping the boat round on its bum as seems to happen when I've got the tabs down to stop porpoising
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C-3PO

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Re: Trim Tabs
« Reply #24 on: December 24, 2017, 11:11:07 AM »

Hey C3PO,
I wouldbe very intrested in how you get on with the moonraker! I have seen moonrakers with adjustable trim tabs on servos. A mod which I  like the idea of as I seem to have to tweak the tabs each time I run mine. Being able to automatically raise the tabs in turns I think could really help stop the nose digging in and flipping the boat round on its bum as seems to happen when I've got the tabs down to stop porpoising

Hi Tom - I'll keep you updated - I think I need to go brushless first as currently I just don't have the oommph on board - can you remind me what brushless motors/esc you used? Would you use the same or with hind sight something else? - Also do you use a mixer for 3 motors?

There is a radio receiver with a built in Gyro and 3 axis accelerometer ..   www.rclife.co.uk/Frsky-RC/Frsky-Receivers/FrSky-S6R-6ch-Receiver
I have no idea how it works, but it suits one of my transmitters.

Hi Kinmel - that looks interesting - I will see if I can find details as to what functionality that RX delivers - tracking your Shannon test with interest - lets hope the weather is kind in the next few days as I am sure there are quite a few people expectant of the next video update....

Quick update - FrSky what a great manufacturer page - all downloads in one place - easy to navigate - https://www.frsky-rc.com/download/

C-3PO
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