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Jan 13, 2010, 08:07 AM
meatbomber's Avatar
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Build Log

1814 HEIC Packet Schooner Brig St.Helena 1/85 scale

after reading some threads which were talking about the possibility to convert a static model kit to running RC. I`ve built a lot of "micro" airplanes in the last 2 years and thus i`m not easily intimidated by small so i want to make a test on how small it`s possible to go

The Subject is a Constructo 1/85 scale St. Helena Brigantine kit.

A 135-ton schooner brig launched in August 1814, was built by Wigram & Green at Blackwall Yard. It entered service on the routes linking Britain with its East Indian colonies. from what i gathered she was in service until 1821.

it`s a beginners kit with a full hull. The details:

Length on deck: 26cm / 10.2in
Beam: 7cm / 2.75in
Displacement: 350g / 12.35oz
sail area 6,7dmē / 103sqin
RC will be 1 x HS56 Fore yards, 1 x HS56 Main Sail sheet and 1 x generic 4g servo for rudder.

i`m intending to put the batteries as ballast in a tube at the end of the fin keel. So far the weights are:

Bats 4xAA 95g
RC equipment: 31g
Hull: 145g (i allready hogged out the hull, but can clean it up inside a bit more to safe some extra grams.)
That leaves me 80g for the rest of the hull, paint, masts and rigging etc.

what do you think will it sail ? Shall be interesting
Last edited by meatbomber; Jan 24, 2010 at 06:26 AM.
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Jan 13, 2010, 09:56 AM
Registered User
80g is not a lot.

You could always go over. But how far?

You could use smaller batteries. 4x AAA or even coin/button batteries. This would give you lighter equipement.

If you leave the fore topgallant and royal sails furled, you will only need about a third of the sail cloth to get the effect. This would save a few grams.

If your fin keel is bouyant, this will allow you to put more weight in the keel bulb (lower down where you want it).

You have really got yourself a challenge here.
Jan 13, 2010, 11:26 AM
Back in the game.
Yellow Baron's Avatar
Wow MB, she's a tiny little thing! Planing to sail her in the fish tank?

I'd go with a 4 cell AAA size pack if you're putting it in the keel, it's something like 60% lighter (that's what I did on my brother's Viking footy). Let me know exactly how you water tight the keel bulb; I used plumber's tape on the screw threads on the pipe for both my clipper and the Viking footy. As always testing will tell .
Jan 13, 2010, 11:33 AM
Damp and Dizzy member
Brooks's Avatar
Looks pretty, MB. I use 4 AAA's for the Goddard, but it's rudder only. I use 4 AA's for the bottle topsail schooner; no weight or space problems due to the wide, light hull.

Tiger- the problem with putting buoyancy below the hull (eg floating fin) is that the floating part negates the righting moment of the weight to some degree. The buoyancy of the hull does the same, but at least has a small lever arm, unlike the buoyancy of the fin keel. If MB has to increase buoyancy of his ship, say to support the 4 AA's, I think he would be better off slapping a smoothed chunk of styrofoam to the bottom of the hull. Now, my fin keels are all solid wood, so have buoyancy, to be sure. But I would not go out of my way to make them more buoyant. If I had the skills, I'd make them out of aluminum; their weight would not be much contribution to righting force (which would still depend mainly on the Pb or battery ballast), but at least it would not be adding to tipping force, either.
Jan 13, 2010, 01:16 PM
meatbomber's Avatar
Thread OP
i will see how i do it with batterys and weight when i`m finished with teh rest of teh mandatory pieces e.g. rudder, RC installation and all the rigging stuff.. actually i`m not overly worried about the weight reserve as all the mss in the hull is already there! allthat gets added now is the rigging. i doubt it will weight more than say 40g. If i have 40g left i would end up with about 100g of ballast (1:3 ballast weight seams ok?) as
the 4 AAs weight 95g, but they displace already 35g, so they are only good for 60g of ballast

another reason why to put the batteries in the keel is because space is at a premium... also if accessible there i might not have to open the hull unless for some major maintenance which makes the sealing easier if you don`t have to contend with opening and closing every time you go sail.

So as it is right now i`ll try to build as light as practicable in the hull and above and then will see how much more weight i have left

I think staying as light as possible is very much desireable due to the small sailarea..

for comparison Larne is about 10% longer but has alomst twice the beam! Her displacement is about twice as much at 750g and she has 1,5times the sail area with 10dmē sail area. she has about 200g of ballast.
Jan 13, 2010, 04:39 PM
Grumpa Tom
Kmot's Avatar
Jan 14, 2010, 12:16 PM
meatbomber's Avatar
Thread OP
build is progressing.. i`llhave to leave out the stanchions on the inside of the bullwarks because i can`t get the deck in and out when they are installed...
Jan 15, 2010, 06:12 PM
meatbomber's Avatar
Thread OP
pretty slow going... i didn`t get to do much today but hope to get teh rudder installation finsihed by tomorrow. Then i`ll have to go for rc installation and hull painting
Jan 15, 2010, 06:53 PM
Where's Pamela?
patmat2350's Avatar
Remember that the smaller the scale, the more issue there is with sails overpowering the hull's righting moment... all the more reason to build in a false keel while you can!
Jan 15, 2010, 07:57 PM
Retired for now
Now this is interesting. Hoep you can make it go. Pete
Jan 16, 2010, 06:18 AM
meatbomber's Avatar
Thread OP
patmat sure she will get a keel fin... i`m thinking about the size of a footys as the sail area is comparable. i`m gonna install the mounting bracket but the keel will have to wait as it makesworking on the hull on the bench a bit of a pain
Jan 17, 2010, 11:51 AM
meatbomber's Avatar
Thread OP
It`s stating to get interesting. I finished rudder installation and placing of the sail servos. Now hooking up all the running rigging below decks. Space is tight
Jan 17, 2010, 12:43 PM
Grumpa Tom
Kmot's Avatar
Working sail masts? Whoa!
Jan 17, 2010, 01:08 PM
Registered User
1967250s's Avatar
You should have plenty of buoyancy with the hull, shouldn't be problem. And I see lots of room inside for servos and arms! Good luck.
Jan 17, 2010, 01:58 PM
meatbomber's Avatar
Thread OP
I changed my mind with the batteries.. because i couldn`t find a suitable container that would be housing them and yet not have too much of displacement to have to add a lot of extra weight to sink it... so i made up a small Lipo pack from some spare cells i had sitting around... so i`ll have 240mAh 2S onbord with a 2A UBEC. Total weight of battery and UBEC is 24g.
So far teh all up weight is 215g. I just had a float check and i`m able to load her up to 375g until the wales are at the water line so i`m hoping to get the rigging done wth about 35g (the masts are already included in the hull weight) so i have 120g for ballast !

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