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Author Topic: Rudder extensions for Graupner Southampton tug  (Read 6492 times)

meechingman

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Rudder extensions for Graupner Southampton tug
« on: May 31, 2006, 08:53:18 PM »

Hi all,

Not exactly a build, as such but here goes!

After another outing grimacing at Southampton's poor turning circle and zero steering going astern? :(, I decided to act! Another club member at Eastbourne said 'double the rudder size', so I did.

Simple extensions were made from plastic card and simply slipped over the existing rudders and, for ease of fitment, taped in place with electrical insulating tape. Off to the lake again and, oh my, what a result.

The turning circle has nearly halved, even at low speed and, albeit using full rudder, I can steer very sharply port or starboard [at will!!] when going astern. ;D? I flattened two sets of batteries practising manouevers but got the hang of it in the end. The only thing I can't do is go astern in a straight line. [Any ideas on that, BTW, as the screws are counter-rotating.] A couple of members said that it now looks like I have a 'secret weapon' for the steering contests, which was very kind, but I still have a lot of practising to do!

Anyway, now I have to make a permanent job of things, and have drawn up a basic diagram. The idea is to make the extensions slip over the existing rudders again [taking the hull apart to install completely new rudders would be a pain, as this is an RTR model and wasn't meant to come apart that easiliy], but obviously they'll be glued on this time.

Any comments or suggestions on the design, dimensions etc of the extensions, or what best to make them from, would be very welcome.

Thanks.

Andy G


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Ghost in the shell

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Re: Rudder extensions for Graupner Southampton tug
« Reply #1 on: June 22, 2006, 09:56:59 PM »

meech, I just changed the rx in my southampton to a 40mhz fm set to allow me to use the T6EXA futaba set, and at 100%EPA i seem to have more throw than when i was using the original RTR radio set, next is to V-tail mix trhe motors with independent esc's as well
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meechingman

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Re: Rudder extensions for Graupner Southampton tug
« Reply #2 on: June 23, 2006, 10:56:34 PM »

Thanks, Ghost. Twin ESC's is next on the list but I just found an 'Active' tug that I couldn't resist. Single screw in a steerable kort. Currently getting a little TLC. Once the wallet's recovered, a 4-channel system with two ESC's will go in. A Model World have already given me a good all-in price for everything, something to do in the summer.
Andy
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Ghost in the shell

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Re: Rudder extensions for Graupner Southampton tug
« Reply #3 on: June 23, 2006, 11:43:20 PM »

meech, it should take you about 20 mins to rip out all the old gear, 20 mins to solder the motors up, and about 30 mins to install everything.  (if my soldering is anything to go by, it will be close to 60mins per motor! *l*)

I have ordered a GWS V-tail mixer, 2x Viper 15 esc's and a Y-lead from westbourne models :)
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Doc

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Re: Rudder extensions for Graupner Southampton tug
« Reply #4 on: June 24, 2006, 04:54:12 AM »

Andy,
The larger rudders is usually the simple answer.  'How' you do it can be not-so-simple, and just depends on what you are comfortable with.  Your (drawn) rudder ought to be very adequate.
Steering in reverse.  There is no simple answer.  At 'best' lots of practice!  While not simple, 'flanking' or backing rudders located in front of the prop(s) is the answer (one of them).  Until you get the boat moving fast enough for the normal rudders to control water flow (good luck!), they might as well not be there.  Always more 'benifit' when you stand in front of a fan, rather than behind it, right?  Same for rudders.
 - 'Doc
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Ghost in the shell

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Re: Rudder extensions for Graupner Southampton tug
« Reply #5 on: June 24, 2006, 02:44:09 PM »

what you could do, rather than put seperate rudders in front of the kort nozzles, is to take the leading edge if of the new rudders, and extend it forwards to ahead of the kort nozzle, and add a lil more depth. this will give you substantially more surface area in clean un disturbed water below the hull. it is partly this reason that the longer robbe rudder on my Neptun is so effective, where though the same shape as the original graupner rudder, its extra depth below the keel means it is highly effectiver at low speeds, not dependant on the prop wash to steer it.
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Ghost in the shell

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Re: Rudder extensions for Graupner Southampton tug
« Reply #6 on: June 25, 2006, 05:53:03 PM »

on another note meech, I was towing a large boat in a towing competition, and though i did not win, what i did find out, is those 2 locking hatches WORK, southampton was flipped a full 180 degree, and though she did not right herself, sahe did remain afloat.? the inside of the cabin body was like a fish tank, however the important bit, the hull where her electronics are, remained TOTALLY DRY, so i have faith in her when sailing in the really choppy stuff

I have started to rework Southampton after a dunking! was doing a tow with her, using southie as lead boat, and well she was rolled over.  (see "well, boss..." thread), on taking the deck off, i noticed that the rudder bar was on hole 3, NOT 4.  that will make quite a difference!
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Ghost in the shell

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Re: Rudder extensions for Graupner Southampton tug
« Reply #7 on: July 01, 2006, 09:40:59 PM »

meech, wiring well under way now :) check the thread in RC groups.com and my well boss thread here
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meechingman

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Re: Rudder extensions for Graupner Southampton tug
« Reply #8 on: July 01, 2006, 10:11:37 PM »

Ghost, were you working without a gob rope when she flipped? I always use one, and Dad did so on the real thing. It's basically just a short length of rope fastened near the stern. I fastened mine to the bollards at the starboard quarter and then ran through the upside down 'U', fastening it there with a clove hitch. The gob rope terminates with a loop, through which the main rope passes. In normal towing, the gob rope is slack, but if the tow moves too far to one side, the gob rope tightens and transfers the pull to the 'U'. This pulls the stern around rather than allowing the towline to move at right angles to the tug and then 'girting' her.

Sorry if you already know this, but it may be useful for anyone who doesn't.

This thread will be edited tomorrow with a pic or two to show what I mean.

The nice fancy rudders I made up to my diagram above flexed too much at the bottom. I've gone back to plan A and am just making up some simple rudders, just over double the original size. I'll check the steering servo to see where the link is later, but I did notice that the servo isn't moving to its full travel either. I'll change crystals in the RX so I can use my spare Futaba TX and see if that changes things.

Andy
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Re: Rudder extensions for Graupner Southampton tug
« Reply #9 on: July 01, 2006, 10:29:56 PM »

sadly meech, no break rope across the tow line. - oops!

now when i removed the deck off southie, i notieced that the rudder bar was on the not at the outermost hole on the rudder, though on the outermost hole on the servo horn.  that will make a lot of difference.

it may be worth cracking into the hull and seeing what your rudder linkage is set at.
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meechingman

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Re: Rudder extensions for Graupner Southampton tug
« Reply #10 on: July 02, 2006, 08:23:42 PM »

Here's a pic of the fancy rudders, they flex at the narrowest point and 'flap' when going ahead. They will be replaced tomorrow.
Changing the TX vastly increased the rudder throw.? ;D The Hobby Engines TX must have a limited end point. I'll take it apart and see if there's a trim pot .... unless someone has already found that there isn't one!

Pix of the gob rope operation are attached.

Andy
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Re: Rudder extensions for Graupner Southampton tug
« Reply #11 on: July 02, 2006, 10:01:35 PM »

thanks meech :)

all i need now is the mixer y-lead and batteries, then im all set!
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meechingman

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Re: Rudder extensions for Graupner Southampton tug
« Reply #12 on: July 04, 2006, 08:17:06 PM »

Hi Ghost,

Well, I went back to basics like I said and came up with rudders a little over twice the original size. They simply slide over the existing rudders once again and, for the purposes of today's trials, were taped in place with electrical tape. To stop the rudders from flexing, a strip of wood was glued to the top and bottom of both rudders.

Changing over to a different TX certainly gave the rudders more throw, without having to resort to opening up the hull [did you have any problems with the small screws holding the bollards in place?].

You can see that I've also given the rudders a bit of what I guess is either 'toe in' or 'heel in', depending on how you look at it. It means that the outer rudder in a turn is always working that bit harder than the inner one.

Anyway, how did the trials go? *!?*!*? amazing, that's how!  ;D ;D Ahead turning circle is now down to about three boat lengths and astern, after about a boat length's travel before the turn kicks in, winds itself up to around two boat lengths. Doesn't seem to matter what amount of power you apply, the turning circles are pretty constant. In a full speed turn going ahead, you can expect a little deck washing. I do have to remember that the rudders now extend beyond the stern tyre fenders, but that's the only downside.

In short, I'm seriously please, and tomorrow's job is to epoxy the rudders in place as a permament fixture.

Andy

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Re: Rudder extensions for Graupner Southampton tug
« Reply #13 on: July 04, 2006, 10:36:57 PM »

meech, the bollard screws came off without a problem, though the small fantail bollards had to be snapped off as they were glued to the deck.  apart from that, little difficulty getting them off
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Shipmate60

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Re: Rudder extensions for Graupner Southampton tug
« Reply #14 on: July 04, 2006, 11:53:42 PM »

Might be worth putting some rudder guards on the stern too, would be a shame to fit new rudders and knock them off going astern!!!

Bob
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Re: Rudder extensions for Graupner Southampton tug
« Reply #15 on: July 05, 2006, 08:21:46 AM »

About the longer rudders.  A guard while they are in the water is nice.  A modified boat stand while transporting is even nicer!  Saves a lot of cussing and fixing...
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meechingman

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Re: Rudder extensions for Graupner Southampton tug
« Reply #16 on: July 05, 2006, 09:56:01 AM »

Thanks for the tip about the rudder guards. I'll see what I can come up with. As for the stand, yes, I've started making a longer one for transport - the 'display' stand at home is already big enough [or too big, as I am told by the 'admiral who must be obeyed'!  ;D

Cheers
Andy
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Re: Rudder extensions for Graupner Southampton tug
« Reply #17 on: July 05, 2006, 06:58:19 PM »

once differential thrust is installed you wont need the rudders :)
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meechingman

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Re: Rudder extensions for Graupner Southampton tug
« Reply #18 on: July 06, 2006, 12:04:03 AM »

I know, I've done it with the real tug! I've just bought 'the admiral' a Severn Class lifeboat [wifeboat?] off ebay. [Not playing with my tugs, no way!!] No rudders, just differential switching on the motors for steering. OK when you get used to it and, yes, it turns in its own length.
Have you got yours finished yet? It would be great if you could post some video of her turning. Next time I go to the lake with 'Heighton', ex Southampton, I'll try and get some footage and see if I can't post it on Youtube or something.

Andy
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Re: Rudder extensions for Graupner Southampton tug
« Reply #19 on: July 06, 2006, 11:13:59 PM »

meech, almost done, just needs extentions for the tamiya leads then im done :)
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Re: Rudder extensions for Graupner Southampton tug
« Reply #20 on: July 08, 2006, 02:50:37 PM »

mission accomplished!

just need to replace the antenna tube as i lost the other one, but for now i can tape the antenna to the deck with sticky tape.

had southampton in the test tank and it spools up fine, mixer works ok, just needs a little balancing.
and with independent esc's the two motors seem to sound a lot more beefier!  given the confines of the bath full turns can not be done but the independent spooling does work

on the steering course its going to be interesting as well to see how she fares against billings smitt nederland as there are two of them in the club. 
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Re: Rudder extensions for Graupner Southampton tug
« Reply #21 on: July 09, 2006, 07:13:34 PM »

well as it happens i have found the antenna straw :) still got a dark on eon the way anyway, the current one looks like a neon strip light or light sabre as its soo bright! however boat vid

http://www.rcgroups.com/forums/showthread.php?t=540614

meech have fun,  its also on RC Groups thread of yours as well :)
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meechingman

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Re: Rudder extensions for Graupner Southampton tug
« Reply #22 on: July 09, 2006, 11:20:53 PM »

Great performance! Going astern is awkward. The screws and motors are counter-rotating so in theory she should come back straight. I certainly haven't mastered it yet.
Andy
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Re: Rudder extensions for Graupner Southampton tug
« Reply #23 on: July 09, 2006, 11:34:05 PM »

What I did notice, your rudder starts from the rudder shaft and goes backwards, a balanced rudder has a section in front of the rudder stem, when the rudder turns it collects water from the other side of the prop instead of missing the rudder all together,
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Re: Rudder extensions for Graupner Southampton tug
« Reply #24 on: July 09, 2006, 11:45:17 PM »

Great performance! Going astern is awkward. The screws and motors are counter-rotating so in theory she should come back straight. I certainly haven't mastered it yet.
Andy

if the engines are turning at different RPM rates, then one is giving more power than the other and consequently it wont reverse straight
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