Semiscale Footy Catboat

Footy Class General Discussion (Footy)
41

A bit busy yesterday, but I have been able to carry out a simple preliminary test of the FCU ( footy control unit )

To have a better understanding of line route at different servo arm positions, I have arranged a makeshift beam with an hole in the same position of the planned fairlead on the roof.

Even if there are details to be adjusted, results are promising enough to reassure me about future sailing tests.
From geometrical point of view it seems confirmed that a boom swing angle of about 85° ( each side ) is possible.

Without doubt there is more friction than usual , and may be that a lot of things can go wrong, but this the fun of experimental footy :slight_smile:

Flavio

42

Flavio

Your FCU is a good plan - Roger Stollery has a “brick” which he drops into this Ant/Rant/whatever but it pokes its servos above deck.

To reduce the friction as much as possible you might like to consider:
A) Use a very light braided sheet line - I have discovered a soft,braided spectra line - I will publish the detail tomorrow - extremely light, low friction sheet. (Please note: most spectra is hard, strong and unsuitable for running rigging)

B) reduce friction at the end of your “arm”
I have salvaged some Fishing rod rings which have a low friction circular lining
and the top ring could be fitted to the end of the arm. Not very traditional!
Good fishing rod rings - especially the first one nearest the reel used to be “agate” when the world was young and my father fished

I also like the crew of your ships, but I have to say I prefer the young lady to Captain McWhirr

andrew

43

This is the spectra braid I was referring to:

http://www.hobbycraft.co.uk/productdetail.asp?productcatalogue=293830

It is so slippery that it needs fishermans knots and/or tube crimps

While on that jewellery page there are many other useful bits of wire, clips and findings for rigging!
http://www.hobbycraft.co.uk/productdetail.asp?productcatalogue=105072
how about these for detachable bottle-screws?
This is the general page
http://www.hobbycraft.co.uk/productlist.asp?ProdPerPage=999&PageNumber=1&catid=201&bcat=2,201&CatName=&SortOrd=&Searchstring=&SizeSearchID=&menuid=&menuid2=&rootcat=&brand=&sizeid=

andrew

44

I’m sure the posted concerns with regard to friction losses in Flavio’s sheeting layout are unfounded. I can’t believe that the final FCU will feature string through plain holes drilled in bits of wood or even the staple perched on an offcut of balsa. Flavio has already mentioned the proposed fairlead in the cabin top and I suspect the staple will end up as something a lot more sophisticated too.

Also, the servo he appears to be using is a GWS IQ 220BB which has quite decent torque values quoted as 42Ncm or 60 oz. ins. at 4.8V

Cheers,

firstfooty

45

Sorry to hijack you thread Flavio, but since Andrew is obviously on line - are you planning to do Bournville on Saturday 9th May ?

Cheers,

firstfooty

46

FF

Yes, Hope so
T’would be nice if Flavio and the Italian tribe could make it as well:D
andrew

47

I have been involved in a deep research about alternative ( slippery ) lines to be used for footy rigging.

Jelwery suppliers are usually managed by pretty girls that are a bit sospicious about my enquiries about the strenght of silver plated hooks, and other unusual problems.

Fishing shops are usually managed by old man that bit surprised that I am looking to leads ( for ballast obviously ) and lines but I am not intersted to hooks and fisherman cloths

I buy balsa in a shop that is a suppliers for architectural models ( buildings, houses and other not floating objects ) and they are also a bit surprised about my careful selection of wood and my need to measure the weight of planks.

Not an easy life for footy builders :slight_smile:

+++

About the crew of my boats :
for unknown reasons, it seems that Elen ( this is the name of the pretty lady ) and her sisters are a bit more popular than Capt Mc Whirr and his bosun

flavio

48

Andrew you are an absolute star. I have been using my enforced idleness to rebuild the fleet and you have just comleted my shopping list
CheersMark

49

Flavio

At the risk of steering this thread off its real, and very valuable, purpose of inspiring the lazy amongst us to get up and actually build something, could I ask for more of your delightful drawings. They inspire the same frustrated longing I fels as a ten year old when I bought a copy of Lezczynski. See the reference on the Vintage Group site

http://www.vmyg.org.uk/books.htm.

Russell

50

Flavio

Thanks, as always, for the pictures, sketches and especally the thinking that you reveal to us

If Elen is going to travel to Birkenhead she is welcome to crew any of my boats.

I have just re-read the thread and the weights you show give me great hope:D
Blackwatch the bread-and-butter carved hull is coming near finished shape and thickness and weighs now at 36gm.
This is without deck, but with the integral keel box a lot of thickness at the transom for the rudder tube (she has an inset blade rudder, not a beautiful creation like yours with laminated, serpentine tiller:D)

regards,
andrew
(I ALWAYS remember that Balsa is a hardwood, and yew is a softwood)

51

Few days far from this forum, I have been busy working with wood, varnish and glue and yesterday I have splashed Brando in tyrrenian sea.

Wind was very light ( about 5 kts ) with gusts non exceeding 8-10 kts

Model weight was 473.5 gr (16.7 oz ) using the heaviest scenario for rc ( heavy receiver, 4 “cheap” AA )

Ballast weight 145 gr ( 5 oz ) - quite light -

Sail area was about 8.8 dm2 ( 136 sq in ) using a preliminary mainsail made using plastic shopper bag , just to have a first taste of sailing performances

FCU has been redesigned and rebuild, adding several small improvements :
friction losses are not so terrific, and removal is simple and quickly ( without screws )

A new rudder has been designed and build ( due to several reasons that are too long to describe )

Performances :
Even if the boat was trimmed a few millimeters too much “bow down” balance and steering performances are smooth.
Brando tack and jibe easily, and seems to be able to go upwind and downwind without troubles.

Longitudinal balance using heavy AA , could be improved swapping longitudinal positions of receiver and batteries within FCU ( another good advantage of rubber bands to screw )

Without doubt performances will improve a lot using lighter receiver and AAA ( a weight save close to 20 - 25 % of total displacement )

Sail plan may be is slighty too big if used outside sunny italy or florida, on final one I will use a more “atlantic” version.

Whipstaff most probably is too sensitive to small building mistakes, and next time I will test a more conventional push-pull arrangement

One more week of small detail to adjust ( and to work on plans ! )

Flavio

a bit of problems with pictures, I will try again later

52

… more picture about brando and the FCU MkII

flavio

53

Flavio,

Looks lovely, must go well:D

So now you put her in the “matter replicator”; dial up X10 to make Dodo and X21 to make Whoopi?
andrew

54

…more pictures about my “other” projects and their crews

:slight_smile:

flavio

ps : elen her her sisters will be happy to see birkenhead soon :wink:

55

Busy days,

unfortunately I have not been able to make progress with final plans or adjustment to Brando, but I have been able to make a deeper analysis about model weight and related matters
Weight breakdown

I have recorded the weight of all parts ( about fifty )
It is interesting to have look at most important weight groups :

empty hull : 97 gr ( about 80 gr of wood , and approx 20 gr of glue and varnish - 5 coats - )
rudder and tiller : 15 gr ( poplar ply )
fin keel ( without lead ) : 16 gr
spars, sail and rigging : 21 gr
Footy control unit : 101 gr
Batteries ( 4 cheap AA ) : 95 gr
Ballast : 130 gr

Displacement : 475 gr
Ballast ratio 27 %

  • it is interesting to see how the situation could be improved using lighter and better electronic stuff -

keeping the same displacement and using 4 AAA and a micro receiver ballast ratio can grow up to 44%
in other words this means extending from about 10 kts up to approx 15 kts the operating range of the model ( considering as limit the deck underwater heel angle )

For racing minded modellers , further weight saving can be achieved using thinner balsa, a balsa rudder and a lighter FCU plank, as well removing internal bulkheads.
I have used in the past also balsa for mast and other spars, to save weight and to have a lower center of gravity. Model shaould be handled very carefully, but is still possible to sail without problems

I hope to be able to test sailing performances of lightweight brando on next sunday …

Flavio

56

Sunny weather and light wind during second sailing test yesterday.

Mainsail, even if still “rough” ( shopping bag cloth ) has been cut to test an “atlantic” sail plan , more or less 20% smaller than the Florida version.

Rudder linkage has been modified to push pull rod system, simpler to build in comparison to the whipstaff version.
Unfortunately most probably I can’t show anymore my artistic laminated tiller

Electronic has been modified using a mini receiver ( about 10 gr ), and four cheap AAA installed into an homemade battery box.

Total displacement was 412 gr
Sail area 810 cm2
Ballast ratio 31%

Based on my calculations in this case Brando should be able to manage up to 10 kts
In case of stronger wind an heavier ballst keel should be used

As it is possible to see from pictures, in this light weather trim, the hull is floating quite high on the water, and the model is slippery and responsive.

Without doubt even if it possible to use AA batteries, a lighter electronic deadweight is definitely a remarkable benefit

Now I will add here and there further adjustments and I must finalize work on plans

… be tuned !

Flavio

Folgore ITA 5
Presto ITA 13
Brando ITA 14
Barracuda ITA 15 - the ultimate footy interceptor :wink:

57

Flavio

Absolutely beautiful!

So you have gone a little lighter on the radio gear and batteries - it must all help the performance and ballast ratio:D We must encourage you towards really light receivers and Lipo battery(s).

Surely even with the pushrod you can fit the lovely laminated tiller and just let it wave to and fro above the pushrod? We would know if you were “paddling”, but you don’t do that do you? [we can always tell when Gary paddles because the water at the stern boils and the waterskiier rises right out of the water:D]

andrew
“balsa chips R us”

58

Andrew,

I will try to fit my laminated tiller toghether with the push pull rod, both for nice looking, as well for sportmanship in order to avoid improper propulsive “paddling” in case of races.

Even if Brando is not designed for speed, I don’t want to suggest such illegal practice.

( I wonder if Gary is using an hidden propeller under the stern of his fast duck )

May be use of micro micro micro receivers ( there are rumours of 3gr wonders ) would be intersting, but I will stay far from LiPo batteries due to their spectacular effects when in close contact to water ( overheating, flames, and even wonderful explosions ).

Danger of fire is not a problem, but noise it is :wink:

f.

59

After few long days spent solving more urgent priorities, work on my Brando catboat is under progress once again.

  • other small details have been added ( name plate, builder plate, etc )
  • a new keel for heavier wind has been built
  • steering linkage has been slighty modified , and a third rudder is arriving
  • a new set of spars is almost ready

Yesterday I have done a third sailing test, once again under a very light breeze

A race has been planned for next saturday again two papayas, two protypes and my other boat - Folgore -

++++

It is very interesting to see , side by side, two opposite design methods : broad vs narrow

see below the pictures of both my footies made to show the remarkable difference of two boats
Both of them are wooden flat bottom classical looking , but their beam difference is quite remarkable…

More news during next days

Stay tuned :slight_smile:

Flavio

Folgore ITA 5
Presto ITA 13
Brando ITA 14
Barracuda ITA 15

60

Flavio, you are a true artist
Rgds
AndyT