1/10 Spirit of australia.

[785boats]

Looking good Richie. I've also used the 'sacrificial foam' technique for cowls. Much easier than making a mold

I still think the most fascinating part of the Warby story is that after a few attempts, he couldn't break the 300mph. The calculations on the rudder showed that it was creating over 1 ton of drag on the boat at that speed. So between runs he cut 60cm off the bottom of it with a gas axe. That was a $10,000 rudder. Then he went out & did the record breaking run.

Have a safe New Year.
Paul.

[Richie the shipwright]

Yeah i love it, got a cool photo taken of rudder just after he cut it...didnt even file it up after cutting!! so australian... Oh well once again, all the fish went on holidays %#@&@##*& (gotta love fishing)..... which left me a bit of time to start thinking about drive system. This is the only part of this build that wont be "to scale" (except for kens beard) A few ideas.... First idea.. A stinger mounted on the back of the rear shoe/ski and an offset rudder. Second idea... a central rudder and twin driveshafts/props. third idea... conventional center strut with twin offset rudders.... fourth idea.. Central srut and rudder (strudder style). Thoughts please people...???? A bit stumped.... Ive never had to find a substitute drive system for a 350mph boat before......

[drwayne]

350mph ? hahahaha

Realistic performance expectations ?

[785boats]

Richie.
I'd be tempted to set it up like the JAE 21 rigger from Zip Kits.
A strut level with the bottom of the ski.And a flex drive. Rudder offset to the side.
Here's the build manual for the rigger. Scroll down until you hit the strut & rudder installations Pages 18, 19, 21, & 30.
If I ever get around to finishing the 1/8 K7 Bluebird, that's the way I'll be doing it.
The rest of the manual is a good read too.

http://www.zippkits.com/21FE.pdf

[Richie the shipwright]

Knew that'd get a bigger bite than i got on the weekend.... Question... how do you scale down speed? Is it just say 1/10 as fast as the real boat? doc...realistc goals?? What are they again?? wanna go as fast as she'll go without killing ken. (or messing up his beard! ) who knows???? work in progress....was going to start with the 2650 kv 3674 i got from joe.... dunno mabee on 4s? that should be at least a little bit mental?? (until i can afford the setup you suggested in pm.!) paul, its funny... the setup on the jae was what made me think of a stinger. Good suggestion. I figured the rear shoe will dictate where it will ride, so depth adjustments are a bit irellevent. and that the only adjustment i may need is prop angle. that why i was thinking stinger. Think its too stupid to try?

[drwayne]

Speedmaster ( or clone) 3/16 strut would do you well, offset rudder
3674/2650 on 4S ? .. wow, there's your turbine noise right there .. !!!!!

Ken was a lucky bastard the UIM didnt ping him for no safety capsule ! haha
Mandatory everywhere now .

[Richie the shipwright]

Think thats the reason they never ran the second boat in anger too... something about being unable to test the cell that they had installed, without drstroying the boat. looking forward to seeing soa2 having a crack when shes ready. ROADTRIP ANYONE??? Thanks guys, more building soon. Have a great new year everyone. :-)

[drwayne]

Think thats the reason they never ran the second boat in anger too... something about being unable to test the cell that they had installed, without drstroying the boat. looking forward to seeing soa2 having a crack when shes ready. ROADTRIP ANYONE??? Thanks guys, more building soon. Have a great new year everyone. :-)

+1
I dont want to watch this one on TV !

Plus, there's plenty of rc ponds between here and there...

[egneg]

Your 1/10 scale would have to do a bit over 100mph (161 kph) to match the 317 mph (500 kph) of the real boat.

http://scriptasylum.com/rc_speed/scalespeed.html

[drwayne]

This is the calc buried in that code ..

[square root of scale model speed/(1/scale size)] x10 = fullscale speed

Richie's 1/10 model at 100mph ? sqrt[100/(1/10)] x10 = 316mph ... nice

also allows this calc to gain speed of model to be true to scale.
scale speed = [square of true 1:1 speed]x[1/scale size]/100

ergo, my 1/6 scale drag hydro, where 100% runs at 250mph .
scale speed=[250x250]x[1/6]/100 = 104mph

good find Chuck !!!

no idea if accurate, but works a treat for those examples !
cheers
W

[Richie the shipwright]

Man i got a headache, but i think i get it....... Didnt think it was as simple as divide by 10. Oh well guys...looks like the challenge just got a lot harder! kens beard will need brushing between runs for sure. Is that sort of speed possible with a boat this size? Seems a little bit too ambitious.... Great info for everyone chuck, thanks.

[egneg]

I doubt it, but 60 mph is doable when you get it tuned. You will be surprised how fast it looks at that scale.

[Richie the shipwright]

No glassing today... 48° c in my corregated iron inferno.... hotter tomorrow...

[drwayne]

That's rather un-Australian of you,mate !
Come on... epoxy brush in one hand, beer in the other.. where's ya spirit ? !
ha ha hic

No glassing today... 48° c in my corregated iron inferno.... hotter tomorrow...

[Richie the shipwright]

Sorry doc.... Call me a softcoc# if you like... finding it hard to stay out of my 50000 litre test tank at the moment... let me see.... Sweating it out in 52°c in my shed... or floating around the pool studying hydrodynamics with a couple of ladies.....hmmmmmm..... These hratwaves are hard to take.... 50° in shed at 11.30 am!!! By the way i only use vinylester resin. Due to overexposure with epoxy in my early career building offshore ocean racing yachts. i have no choice but to stay away from epoxy...... makes my skin fall off!!! Vinylester is a modified epoxy resin six times stronger than polyester for the same weight. (epoxy is 8x stronger) It uses the same hardener as polyester, is fuelproof, and doesnt soften with heat. . a great material. You should NEVER LAMINATE ABOVE 30°C. Doing so will cause excessive exothermic heat and make the resin crystalise and become brittle. NOT GOOD!! Oh well, Nothing for it friends ...... back to the test tank i guess... :-P