Spirit of Texas Drag Hydro

[drwayne]

Gday Paul
Outwards is fullsize spec.
inwards I'll try next run... also a higher torque servo.
chuckle.. in a straightline this thing rockets.. cornering is not a consideration for full size
2x big props same rotation on a short hull will induce prop steer, which is a speed killer to cancel out... once owned a twin rigger, same rotation , prop steer a beech.
This straight lined with any rudder input above 1/2 throttle.. but it's possible the rudder was unable to move due dual opposing wash over-riding the servo.

All a learning curve ..

How's the water level in your soggy neighborhood ?

Doc.
Have you thought of reversing the props (& shafts) & motor direction so that the props turn in at the top instead of out. I know that one way is better than the other but I can't remember which.
Also, I know that it is a different kettle of fish, but the big twin riggers have the props spinning the same way or they just won't turn. Could it be the same with a twin V with the drives close together?

[TheShaughnessy]

If you find prop froth to be the steering issue maybe you should try the rudder position before the props. Any reason you couldn't have the trailing edge of the rudder even with the trailing edges/tips of the prop? Is there a clearance issue.

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[Megabiker98]

If you find prop froth to be the steering issue maybe you should try the rudder position before the props. Any reason you couldn't have the trailing edge of the rudder even with the trailing edges/tips of the prop? Is there a clearance issue.

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Would reduce ur choice in prop size quite a bit!! Which would be a big downside to that!

[Chrisg81983]

Glad the maiden went well any video yet

[785boats]

Doc.
I figured as much with a short hull, but it was just a thought,
Yeah. There's a bit of flooding around in the Brisbane area, but not anywhere near as bad as a couple of years ago.
I only suffered some water damage downstairs because the wind blew the rain into the front Verandah where it pooled against the back wall & ran down & into the games room. Been here 25 years & that's never happened before. A big patch of Parquetry has lifted & buckled. No biggie. I'll just wait until the wood dries out & glue it back down & reseal it. There are lots of people worse off than me.
Has the storm reached you guys yet?

[dogg]

Hey Doc, still waiting to see the monster run! Cant wait....

785 its a b*gger to be hit with that weather again up there, some have only just rebuilt. Pretty gutting for all affected...

[drwayne]

If you find prop froth to be the steering issue maybe you should try the rudder position before the props. Any reason you couldn't have the trailing edge of the rudder even with the trailing edges/tips of the prop? Is there a clearance issue.

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designed to be propelled by x665 ( maiden with x457 ).
There is a 13mm gap between blade tips at that 65mm size.
However, cavitation was noted with the 'smaller' props.. 65mm may compress cleaner water across the rudder....
Measuring for right offset rudder as an option .. !

[drwayne]

Hey Doc, still waiting to see the monster run! Cant wait....

785 its a b*gger to be hit with that weather again up there, some have only just rebuilt. Pretty gutting for all affected...

LMK when the next SAW is in Vic !

Qld: Housing developers need to be accountable for establishing housing estates on known flood plains . .. the bloody idiots.

Best of luck to all !

[RandyatBBY]

Moving the rudder forward and over to the right side will help a lot. You did put on a little turn fin? about 15MMx15MM.

[drwayne]

@Randy. The maiden turn fin was from 45 sports hydro, approx 65x75deep.
There was no steering yaw movement when under way 30%+ throttle.

Before any structural/mechanical changes from the proven scale setup ...
First challenge is doubling torque on steer servo.. !

do remember, full scale dont turn.....

[Megabiker98]

Ya full scale don't turn for crap!!! Hahaha the rudder is pretty much used to make minor corrections!!! Lol. But ya I would say first upgrade which gets priority would have to be a upgrade servo of some sort!!!

[f1rogers]

Does it turn at low speed, just above plane?. That might be your best bet for turning, cause the real ones dont turn at speed, usually not up on plane when turning. I once asked john hipwell what it was like a to drive a twin prop Top fuel hydro and he said " its a nice, stable boat until you have to apply rudder under power, then the boat gets really pissed off". Now your hull should be the "big" curtis, which is even longer than the "deaver" hull that hipwell drove. Just some thoughts. My 21" TOXIC ROCKET wont turn on plane either, rigger type.

[lenny]

I would try motor direction so that the props turn in at the top instead of out to.
It made a big difference for a big mono with twin outrunner setup,
Like night and day.

Do I miss the videos of it ?

[srislash]

Video,Video

[Xcesive8]

Just a thought, could be a waste of time in your opinion..
But if you have a go pro or a cheap hobby king camera you could mount it on the back looking down at rudder and props to see whats going on back there. I did it on my CT03 worked a treat.

??