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Author Topic: Newbie Advice re: Kitshack RTTL launch build  (Read 4881 times)

sigfortunata

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Newbie Advice re: Kitshack RTTL launch build
« on: August 26, 2015, 01:55:43 PM »

Hi I'm new here and this will be my first try at model boat building. At 55 I've got lots of modeling experience, plastic kits, RC cars, balsa planes but I've never built a boat!.


I've picked the RTTL as it gives plenty of scope for detailing whilst being a working model. However I have a couple of queries. Like I said I'm familiar with the basic RC type set up for cars but can it be the same for boats.  I've got 7.2 batteries, 27Hz transmitters, receivers and crystal, car ESc's and servos. So....


Can the same radio gear be used in a boat?


I'm planning to build it using two 540 motors, will they work OK?


What advice can members give me on prop type? I'd like to fit brass 3 blade but what sort of size and pitch?


I've checked out the RTTL builds members have posted and they look great.


Thanks in advance for you help....I'm sure I'll be back for more


Steve

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TailUK

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #1 on: August 26, 2015, 05:19:53 PM »

Which size RTTL did you get, large of small?
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Martin [Admin]

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sigfortunata

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #3 on: August 26, 2015, 06:02:37 PM »

Which size RTTL did you get, large of small?




The 28" version as I've never built a boat before so I'm presuming that's the small version?


Steve
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sigfortunata

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #4 on: August 26, 2015, 06:15:19 PM »


Hey Steve,
Welcome to the Mayhem!

See:

http://www.modelboatmayhem.co.uk/forum/index.php/topic,32068.msg316645.html#msg316645
https://www.facebook.com/pages/Kitshack-Models/190942824384283


Thanks Martin


I've read this the threads you have posted and the build by Bluebird of the bigger version, both are really informative and I've bookmarked them to reference when I start my build. Although they give motor and prop advice there seems to often be a deviation away from plans by experienced modellers. I had in my mind fitting 540 motor as they give up 18000rpm (Bluebird suggests 17000 -21000 rpm motors) to get the model to plane) and I have them readily to hand from my RC cars.


Steve



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TailUK

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #5 on: August 27, 2015, 10:41:39 AM »

If my memory serves me I seem to remember mention of 480's for the 28" version.  I would have thought that 540's would work as long as you don't give it "all the beans" when you're running it.
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sigfortunata

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #6 on: August 27, 2015, 10:54:30 AM »

All the 480's I've checked out on line seem to be brushless and water cooled which pushes up the costs which was why I was trying to stick with the old skool brushed motors and kit I already have.


I have seem one brushed recommended for planes.... are plane and boat motors much of a muchness?



However I agree some judicial use of the throttle may be in order if it ever gets  into the water, I want it to plane but not become a plane!!!


Off to the Model Boat Convention near Warrington on Sunday so may find some answers and pick up some parts there hopefully


Steve
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TailUK

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #7 on: August 27, 2015, 11:30:32 AM »

Don't forget that if you're fitting 2 props they should be left and right handed.  This eliminates "torque steer"  as you have them rotating in opposite directions.
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sigfortunata

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #8 on: August 27, 2015, 11:59:07 AM »

Don't forget that if you're fitting 2 props they should be left and right handed.  This eliminates "torque steer"  as you have them rotating in opposite directions.


Thanks for that TailUK, I read that the RTTL needs a keel if fitted with one prop otherwise it wanders so that's why I wanted to go down the 2 prop path.


Can I just clarify, The motors turn in the same direction  but the props are LH and RH  blade pitch so "push" left and right helping to keep the forward motion straight ahead rather than 2 LH props pushing in the same direction which would cause the boat to veer ?
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John W E

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #9 on: August 27, 2015, 12:24:13 PM »

hi there sigfortunata

The motors that I fitted and kept in the hull were the MTronik Vision Motors and these are quite adequate for getting this model on the plane with a good duration of time on the water; using 2 400 mAh P NiCad batteries; the reason that the props on this model rotate in the same direction was to keep it in line with the original real 'I am' vessels and the reason these had their props rotating in the right direction was a greater speed.   If you read the log properly you will see that the vessels were prone to smashing the bottom of the boats through wave hopping and prop torque steer.

The actual prop veering off at high speed does happen in the model when you have the props rotating in the same direction and it adds to the fun of the model, i.e. trying to keep it on a straight line.

aye
John
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TailUK

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #10 on: August 27, 2015, 12:58:30 PM »


Thanks for that TailUK, I read that the RTTL needs a keel if fitted with one prop otherwise it wanders so that's why I wanted to go down the 2 prop path.


Can I just clarify, The motors turn in the same direction  but the props are LH and RH  blade pitch so "push" left and right helping to keep the forward motion straight ahead rather than 2 LH props pushing in the same direction which would cause the boat to veer ?

It could be a bit confusing but left and right handed props turn in opposite direction (easily achieved by switching the wiring on the motor)   The other great mix-up you hear a lot is that this is "Contra-Rotation"  It isn't!  The correct term would be "Counter Rotation".  "Contra- Rotation" is 2 propellors rotating in opposite directions on a single shaft.  Classic example is the propellers on a torpedo.
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Perkasaman2

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #11 on: August 27, 2015, 02:50:37 PM »

The props on the original boat turned in the same direction because Vosper used the same off the shelf gearbox on both shafts to save cost. Vosper were forced to retrofit trim wedges to the stern to lower the bow and reduce slamming of the forward hull. Twin prop installations are usually configured to turn either inwards or outwards to avoid or cancel out excessive side thrust generated when both props are turning in the same direction.
Inwards turning props are considered to give speed advantages while outwards turning props are found to give low speed maneouvering and handling advantages.
The hull slamming problem of the RTTL at speed caused substantial forward lower hull damage to frames and planking. Vosper were required to repair it and add a further layer of mahogany to the hull bottoms for extra strength. It is unclear if the whole fleet of RTTL's was similarly modified.
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TailUK

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #12 on: August 27, 2015, 03:18:09 PM »

I think after the Mark 2 or 2B they started using Metal or Fibreglass layers on the hull bottoms.   

So just to clarify now that we've confused the poor man.  The prototypes had 3 then later 2 props all left-handed. 
The model could have a single shaft or twin shafts but 2 left handed props (ala Prototype) would give issues with steering.
Twin Left and right hand props on the model should turn inboard to make it quicker and counter rotate to eliminate "torque steer"

?
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sigfortunata

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #13 on: August 27, 2015, 03:21:42 PM »

Thank you this is all really great advice and background information.


hoping to get more info at MBC on Sunday 


I'm really looking forward to starting this project. 
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John W E

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #14 on: August 27, 2015, 03:22:38 PM »

this may help to clear things up

http://www.asrmcs-club.com/boatswebsite/galleryrttl.html
aye
john
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sigfortunata

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #15 on: August 27, 2015, 04:06:35 PM »

Indeed a useful site for reference, I think the Kitshack RTTL is a representation of either A Mk1B or Mk2 with the grill affair in front of the wheelhouse.
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John W E

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #16 on: August 27, 2015, 04:21:30 PM »

hi ya there sigfortunata

Just out of curiosity, I wonder where you purchased your model from?    I have been searching the web to see if there are any other builds of this model for you and a couple of times I have come across this website :-

http://www.endole.co.uk/company/07930745/kitshack-models-limited

it seems to indicate it may be being restructured or something of that nature - interesting - possible bit more investigation needed.

the Grilled thing in front of the bridge is in actual fact a series of lockers which contain ropes etc., and they are made up of lattice work.  They are therefore open to the environment so that all the water that collects can drain out.

aye

john
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sigfortunata

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #17 on: August 27, 2015, 04:58:43 PM »

Hi Bluebird, I believe Kitshack have gone out of business, however I found one of their kits on Ebay from a seller called Collectorslottoo in Norfolk.


Their advert said they had sold 10 and mine was the last one and their advert was as follows


Back by popular demand. RAF RTTL kit produced with pre-printed balsa and quality Birch Plywood parts ready for cutting out and assembly. Includes balsa and dowel for final finishing to complete davits, mast, etc, Kit includes full size plans and full instructions. Kit excludes paint and finishing materials but everything else is in the box, for cutting out with basic craft knife and fine saw, glue, and sanding block. The photo in the listing is one of our completed models, made by a previous purchaser. Suitable for R/C to use a 400 or similar motor. Motor, prop shaft, prop, rudder etc. is not included in the kit.


I researched Kitshack a little and it seems they were a small company that had lots of plans and made kits up to order but Company House says they are now dissolved so maybe this is old stock or somebody else is doing the same thing??
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Stan

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #18 on: August 27, 2015, 08:54:29 PM »

Hi guys contacted kitshack earlier in the year to be informed they were closing down no more information at this time.

Stan.
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sigfortunata

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #19 on: August 28, 2015, 09:23:17 AM »

I picked up the 28" RTTL for 42 in P&P, wooden parts only, some cut, plans etc, no running gear or fitting via Ebay
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Martin [Admin]

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Re: Newbie Advice re: Kitshack RTTL launch build
« Reply #20 on: August 31, 2015, 09:13:37 PM »

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