1/13th scratch built Atlas (G.Finlay plans)

[mejson]

first of all hi to everyone interested more or less in models, DIY and other hobbies that women don't necessary understand :)
i started to build that hydroplane boat few weeks ago and reading through OSE I thought I'll share progress of my built with you

I got G.Finlay plans and had them printed (regular ink printer) and combined together (lol that was first challenge to make 26" bulkheads of A4 paper)
then balsa, epoxy and other stuff arrived, frame is made of 2.5mm (3/32) balsa with epoxy and 80g/m2 fibreglass on each side (like a balsa/fibre/epoxy sandwich) makes it really
strong and resistant to bends, control plate has been made of 2x1.5mm balsa (1/16) and fibre in between (glued and pressed with epoxy) - again makes it very strong piece.

sheeting is made of 2.5mm balsa, i'm quite surprised by current shape and look of this hull, there are few imperfections but overall i'm pleased with outcome.
I've learned my lessons too:
- it is worth to bend balsa(plywood) before sheeting; either steam machine or boiling water helps - let it dry - it's so much easier to apply parts afterwards,
and what's important too there is much less tension in the frame
- do not apply too much force when sheeting, wood breakes easily lol
- it's better to have more balsa rather than less (hence sponsons' bottoms and sides as well as nontrips going over the edge) - will be cut and polished to exact requirements

anyway, next step is
- epoxy interior and place fibre cloth, epoxy again, fill in sponsons with some foam
- to polish and sandpaper all imperfections and the whole hull,
- few layers of epoxy on the outside to make the palsa stronger,

hadn't think of a config yet but probably 7.4 LiPO (got few of them for my car) and ~4kV BL motor - so far hull is only ~290g (10oz)

as a family guy, won't be able to update you on daily basis however will try to make it as often as possible and when something new comes

next boat is a 36" cat ( thanks to Jesse J for plans) will try to make it in twin config (scratch built of course)
atlas13th01.jpgatlas13th02.jpgatlas13th03.jpgatlas13th04.jpg

[mejson]

foam filled sponsons and some other stuff made, some sanding left

[mejson]

and finally season started...

http://www.youtube.com/watch?v=hp6eBlNhOUk

unfortunately need to seal shaft stuffing tube so the water wouldn't come up to the hull :) and will test it with bigger props...

[Jesse J]

Hi Tom, welcome to the board!
I built this boat as my first real FE five years ago and really enjoyed it. I had good luck with a 3000 kv motor , 3s and a 432 prop. Think about a metal prop, much more efficient and durable.

Good luck with the cat - you have proven your building skills with the Atlas!

[mejson]

Thanks Jesse! your compliments are much appreciated...
even though I've read a lot about RC boat building and setups, reality is quite far away from theory and mistakes are unavoidable
but I think i'm much better prepared now for CAT with twin motor setup, i.e. that plastic cardan joint (last pic) blow off when ran with 3S setup :) - must say I expected it
i will definitely set it up with metal prop and based on rough calculations from that first run she's had, you seem to be right about 432 prop (i mean efficiency and current consumption)
will try to run her this weekend and put some video with different props and perhaps some GPS reading...

[Jesse J]

Oh and these hydros are designed to turn right in an oval. This way you can hold full throttle even in the turns - probably better to run where you have no waterborne spectators...
Enjoy!

[mejson]

at first run i forgot to install turn fin and didn't limit servos hence boat upside down in first turn... :)
got a lake (7km long 500m wide) and it's flat like a table most of a time...happy days are coming

[mejson]

well, not that happy days motor burned out and blew up 200A ESC (thankfully cheap one)
too thin cooling silicon tube got bend and caused no water cooling reached motor, second thing may be cooling intake placed in rudder on the left hand side might have not got enough water in right turn...
ESC was cold so there was enough water coming through prop intake...but I did run it unnecessarily even though motor was quite warm...

currently, i'm waiting for new motor to arrive: E-max B3650 3400kV and I've modified cooling system, tests - soon

[JimClark]

tail is dragging where was our strut adjusted to and also your CG

[mejson]

CG is indeed little bit too far behind sponsons, but it'll be extremly hard to move it forward...
do you think that changing a prop angle would improve it? don't want to add extra weight to it

[siberianhusky]

Sometime a bit of lead in the nose is required, my 30" hydro has somewhere in the ballpark of 4oz in the sponson tips. Goes much faster with the weight because the boat is actually running correctly as opposed to dragging the tail then getting way light on the sponsons.
I hate adding weight to a boat but there was no way I could get the batteries far enough forwards.
I've had a thing for the Atlas since I was a kid, it's on the short list for my next 1/10 scale hydro after I get my 1/10 1957 Miss Wahoo running.
So many boats, so little time! Currently have 4 scratch built projects on the go plus the ones that are already finished and running.
Nice boat!
Cheers

[mejson]

thanks m8! your wise thought is much appreciated, they made me feel less bad putting extra weight in front :)
i will redo canopy and painting as it was made quickly to have her floating for spring season, i got new motor today E-Max B3650/10 3400kV, stronger silicone tubes...
will stick to 3S2P 2650mAh which should give me 6-7min running time or better if i'll improve CoG
currently i'm working on a tug boat to have a rescue option to paddles :)

[mejson]

I've installed new motor and improved cooling system - temp.on a motor 23'C :), however, it doesn't spin as it should...
it started nicely but in few seconds died like it would have rpm limiter installed, it doesn't run well since,
I reprogramed ESC - nothing, i'm worried that old motor might have damaged ESC so I will test another ESC with new motor to narrow down suspected parts and find a root cause..

[mejson]

ok, new ESC and 3400kV motor, 32mm prop and max.speed of 51km/h, temp on ESc is ~50'C, motor is getting to 40'C in front part so I guess around its back should be ~60'C, still need to work on that CoG
running time ~5mins with 2x2650 (parallel) which roughly gives us 63Amps...
anyway, need to modify cables and connectors' (their soldering), plastic covers got melted on few of them so temp must have been very high..but overall i'm happy bunny since it's a first project (didn't sink yet) lol
GPS_test.jpg

[mejson]

i've corrected CoG and prop AoA, you can certainly see higher speed, but poorly soldered joints melted so had to do it right this time...