Spirit of Texas Drag Hydro

[Megabiker98]

Just for thrills, 0 to 240mph in 4 seconds, boat called "Madness".[ATTACH=CONFIG]93091[/ATTACH]

well they do the 1/8 mile in 4 seconds there probably at 250 in the first 2 seconds id say!!

[drwayne]

Thanks. Outwards rotation

Just for thrills, 0 to 240mph in 4 seconds, boat called "Madness".[ATTACH=CONFIG]93091[/ATTACH]

[twissted]

That's faaaast!
Props next to each other would make sence to run them outwards to keep trubulence between the props at a minimum.
I think cupping them would help as well.

[drwayne]

That's faaaast!
Props next to each other would make sence to run them outwards to keep trubulence between the props at a minimum.
I think cupping them would help as well.

First day outwards rotation runs1,2,3 returned 10kmh faster.. too much skippy action when inwards run 4+5.

[drwayne]

Out again today to try some setup options.
Found lots that dont work :p
Left sponson tip now wears a small bandaid, will write 'ouch' soon.

Lack of cowl makes for very uncontrolled flight at speed.
"Driver's capsule" at front will aid nose down force.
W

[srislash]

You'll get it Doc,and we'll learn

[Megabiker98]

Have u though about trying to get the motors to spin a little faster when turning one way?? That might give a little bit of help possibly

[Chrisg81983]

Higher rpm and smaller props is were its at. I had big twin hydros and they hated big props. Soon as I went to 57's cut to 51-52 mm or even a set of 447's worked pretty well for me. I had to detoungh and slight back cut the cut 57's. I will try to get u some pictures up for u....

[drwayne]

Higher rpm and smaller props is were its at. I had big twin hydros and they hated big props. Soon as I went to 57's cut to 51-52 mm or even a set of 447's worked pretty well for me. I had to detoungh and slight back cut the cut 57's. I will try to get u some pictures up for u....

Hi.
This ran smooth with x447s.. the ride is smooth.. but launch dismal, top speed was embarrassing @60mph ... props kept 'breaking out'

This needs "driver's capsule" for nosecone down force and the airborne stability that offers.
A large object taped to nose created a down force that made this run better.. but the fly-on attitude made some sphincter concerns as it touched the wall ! ( hello bandaid, thanks Doc ! )

After launch this lifts at motor thrust point, and hull raises level from there.. then scoots along airborne on prop thrust, flying horizontally. ..
Dont get this issue confused.., this thing rips 70+ after launch at 1/2 throttle and building .. and yet it stumbles due prop on/off as hull raises/lowers due that thrust vectoring transfered to motor face, with props skipping along..
CG movement induced nose down or up attitude ( sink or fly respectively )...

Removing lift from props may help a smoother push through water/air... and then I will revisit CG placement.

[Richie the shipwright]

I think chris has raised a good point. With smaller props the boat did seem MUCH happier!. A few kmh slower mabee... but as you said doc, you have a lot of throttle left in your bottle!! Just hitting the throttle seems to just make her very angry... mabee slightly slower "trigger finger" would smooth out the launch a bit? Its a total animal mate, just needs a bit of training!

I wonder if youre the first bloke to dicover the aerodynamic/downforce properties of an 8m Stanley measuring tape??? :-)

Im going to paint a sign on that wall you keep aiming at as a little reminder......"TURN RIGHT DOC!!!"
(Or a big bullseye target...) :-)

[drwayne]

Smaller props gave cavitation on launch, lowered top speed, yet made little change to the ride attitude.
Props not prime cause the observed control issues.
Aerodynamics now the focus.
Under 60mph this handles great.
Over that it's like a rigger with a wing up front !
W

[Rumdog]

Smaller props and motors. More rpm.

[Heaving Earth]

Where are the batteries?
Thing rides like a v hull, nose bouncing around....

[drwayne]

Smaller props and motors. More rpm.

This is a drag boat, not oval.. . x447 although smoother(slower) launch did no better than x457 at speed
In fact they 'broke out' ( broke into cavitation) well before throttle achieved by x457s when they did same.

Where are the batteries?
Thing rides like a v hull, nose bouncing around....

Under launch acceleration this lifts and rides // parallel to water ... struts on water.. nose attitude constant
Nose slapping is due holding partial throttle ( blows over +70mph) ..Im not accelerating to 100% before button off .. thus the hull leaps up and goes , then no additional throttle and it starts to drop off thrust lift vectored at motors .
CG is not same as in a sports hydro.
This is to achieve straightline launch and go, not oval as some these tests suggest..
....it does circulate ok in oval form (~1/2 throttle @60mph), however that is not my intended goal.

regs
W



Tests yesterday with ad hoc downforce object improved handling dramatically

Will post results with down force from cowl ( when cowl arrives)

[jcald2000]

1/2' deep air dam across the tunnel will help.