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Author Topic: Avispa - Early Torpedo Boat  (Read 4809 times)

GG

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Avispa - Early Torpedo Boat
« on: November 16, 2010, 04:36:20 PM »

Having taken the plunge an bought a twin cylinder steam engine, the Graupner LST-L unit described in last October's issue of "Model Boat", a suitable model was needed.  Something appropriate for stream power but the popular choice of an open launch did not appeal, after a little thought, a model based upon the the early Torpedo Boats looked promising.
The only drawback was their slim hulls which did not appear to be a good match for a bulky and weighty model steam plant.  After a long cycle of sketch designs, calculations and back to the drawing board, a model length of 40 inches seemed to work.  It gave a beam of 4 inches which was just wide enough for the boiler but the draught had to be increased to keep the steam plant below deck level.  This resulted in a final model weight of 11 pounds which was greater than originally intended but at least allowed for enough lead ballast inside the hull to ensure it always knew which way to float!
The hull was constructed in my favoured "open top box" method but using a thick timber bottom sheet and plywood sides.  This makes it a tough model and strong enough to cope with the large deck openings.  The original vessels had a simple if not sparse appearance which greatly helped to keep the top weight down.  The model ended up around 1/30 to 1/40 scale and hopefully looks the part.
The first sailing trial was undertaken without the main deck fitted.  This avoided having the deck blown off when the safety valve operated.  The model was quickly modified to feature a suitable deck opening which is hidden under the searchlight base.  The second run was in public and I must be getting there as the model ran perfectly for the 25 minutes a full burners gas tank will last.
I'm still moving up the learning curve with this model but recognise the need for the extra preparation/attention that steam power needs before, during and after each sailing run. Perhaps this is why some people love steam power whilst others avoid it like the plague?
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tonyH

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Re: Avispa - Early Torpedo Boat
« Reply #1 on: November 16, 2010, 05:58:13 PM »

Nice one GG,

What pressure is it running at in the pic and is that flat out?

Tony

Just thinking because Mo(cogear) is trying a similar vessel with twin screws and it would be handy to get the 'feel'. O0
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GG

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Re: Avispa - Early Torpedo Boat
« Reply #2 on: November 16, 2010, 09:31:28 PM »

Tony,
        I tend to operate around 2 bar pressure and the model is shown running at part throttle.  The drive line still needs "running in" as it is not as smooth as it should be plus some experimentation is needed to find the best propeller.  The best speed I have had yet is a shade over 2 ft/sec but I'd like it to be nearer 3 ft/sec.
Handling is very good and it steers when moving astern.  The inertia (from the 11 pounds weight) prevents it being "thrown around" but probably adds to a more realistic sailing performance.
As I said in the first post, still moving up the learning curve with every outing.
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Edward Pinniger

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Re: Avispa - Early Torpedo Boat
« Reply #3 on: November 17, 2010, 06:51:01 PM »

Looks very nice on the water! This time of year may not be much good for model boating most days, but it at least means you get realistic "smoke" from steam powered models  :-)

After having seen a 1/96 TBD at the Warwickshire show with a semi-scale/box construction lower hull like your designs, I was surprised at how effective it looked and might try something similar myself in future (I'm no good at building "true scale" hulls) maybe based on the plans for HMS Velox or Havock which I have.
Are you planning to publish/sell plans for this design?
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tonyH

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Re: Avispa - Early Torpedo Boat
« Reply #4 on: November 17, 2010, 09:19:57 PM »

It does look good, especially if that's half throttle. It'll be interesting to see what the bow wave is like when it's fully sorted. It would almost be worth cheating and trying a small underwater 'ram' below the line to lift the water a tad.

Tony
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tobyker

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Re: Avispa - Early Torpedo Boat
« Reply #5 on: November 17, 2010, 09:51:54 PM »

That really is very sweet. But where is she steered from? It's going to get jolly hot in the conning tower if the helmsman has to stay in there all the time!
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GG

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Re: Avispa - Early Torpedo Boat
« Reply #6 on: November 18, 2010, 09:47:56 AM »

Edward,
         Now I know it works the plans will be drawn up and construction article written then sent to the Editor of "Model Boats".  As to when it would, if accepted, get published, your guess is as good as mine.
Glynn Guest
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steve pickstock

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Re: Avispa - Early Torpedo Boat
« Reply #7 on: November 18, 2010, 10:30:23 AM »

If you weren't going to use steam for this model, what size of electric motor would you run?
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GG

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Re: Avispa - Early Torpedo Boat
« Reply #8 on: November 18, 2010, 05:19:10 PM »

Steve,
          Cannot honestly answer that question, if I had built this model for electric power then it would have been built differently.  Less draught and hence less weight which is likely to make a big difference in the power needed to drive this model.
Selecting the right motor for any model is something of a "black art", well it is unless you build the same type of model over and over again!  I know enough not to make any recommendations unless they have been tested and proven first.
I do plan to take the steam plant out and try electric power to get some idea of steam-electric equivalency for future reference.  But, this will have to wait until I have fully tested this model with steam power.
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GG

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Re: Avispa - Early Torpedo Boat
« Reply #9 on: November 23, 2010, 10:19:54 PM »

Such a fine morning, I could not resist taking the Avispa out for another run.  Quickly raised steam and all the joints remained tight.  I had problems due to my continual tinkering as some of the pipe connections developed minor leaks.  Took some advice from a local Auto shop and tried some RTV silicone "Gasket Maker" which seems to do the job provided you use the smallest amount, too much runs the risk of creating a blockage (don't ask!).
The hole made in the deck over the safety valve did its job as I found out when launching the model.  I was covered in steam but the deck did not blow off!  Just settled for gently sailing around whilst taking some sailing photographs and had an enjoyable 20 minutes on the water.  Must be getting better a the insides were not half as wet and messy as before.
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mogogear

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Re: Avispa - Early Torpedo Boat
« Reply #10 on: November 25, 2010, 04:40:38 AM »

As stated elsewhere... :-)) :-)) Good to see more of this era boats on the water and being worked on in shops!

Nice GG
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HS93 (RIP)

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Re: Avispa - Early Torpedo Boat
« Reply #11 on: November 25, 2010, 06:38:25 AM »

Looks good try a prop with a lot of blade power more than revs, prop shop do some nice steam props but try and get an idea with a cheap prop first, if you have a brass soldered prop you can put a bit more pitch on you need 3 blades.

good luck with your return to steam I hope you enjoy it better than your last exploits.

peter
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GG

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Re: Avispa - Early Torpedo Boat
« Reply #12 on: November 25, 2010, 09:49:08 AM »

HS93 (peter)
Re "..I hope you enjoy it better than your last exploits"
????????
Glynn Guest
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HS93 (RIP)

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Re: Avispa - Early Torpedo Boat
« Reply #13 on: November 25, 2010, 10:12:05 AM »

I thought I had read in a article that you had  hinting that you where not overjoyed with steam the last steam plant you had and that this one had gas so you where hoping for more or was it another article by some one else I was reading..

Peter
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GG

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Re: Avispa - Early Torpedo Boat
« Reply #14 on: November 25, 2010, 02:25:37 PM »

Peter,
        I think I can say that I have "enjoyed" all the models designed and built so far.  Satesfaction being achieved in many different ways, sometimes it a long cherished project finally come to fruition, others it was the reward of eventually making the damn thing work, even proving "experts" wrong can give you a nice warm feeling.
If you are referring to the "Getting steamed up again!" article in last October's Model Boats, then I don't think it was said that I did not enjoy my my previous three steam powered models.  I did point out the drawbacks of sailing with a simple single cylinder single acting oscillating engine, namely no control of speed.  But, even this problem lead me to try a type of Kitchen rudder that worked, not perfectly but well enough for the little effort it took.
I did comment that using a gas fired boiler would avoid the build up of deposits that solid fuel tablets produced. This drawback only requires the use of a damp rag to wipe the deposits away and could never spoil my enjoyment of sailing steam powered models.
Glynn Guest
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HS93 (RIP)

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Re: Avispa - Early Torpedo Boat
« Reply #15 on: November 25, 2010, 05:19:48 PM »

yes anyway , try a large bladed prop unless you have tried one already.
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Jack.H

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Re: Avispa - Early Torpedo Boat
« Reply #16 on: April 15, 2011, 08:58:36 PM »

Can i see a video of the boat? :}

Jack.H
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GG

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Re: Avispa - Early Torpedo Boat
« Reply #17 on: April 16, 2011, 09:48:16 AM »

Jack.H
            Only if you take it.
GG
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Jack.H

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Re: Avispa - Early Torpedo Boat
« Reply #18 on: April 16, 2011, 01:01:03 PM »

What does that mean?

Jack.H
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GG

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Re: Avispa - Early Torpedo Boat
« Reply #19 on: April 16, 2011, 08:02:19 PM »

(If you want to see a video of this model then the) only (way is) if you take it (because I neither own nor desire video recording equipment).
GG
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Jack.H

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Re: Avispa - Early Torpedo Boat
« Reply #20 on: April 17, 2011, 01:20:22 PM »

thanx for explaining
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