T-Hydro 135.9mph pass at Legg Lake SAW's Jan 25th

[RaceMechaniX]

Thanks to Tony H for catching the run:
Blew the tail out at 2/3 mark before the final mark. It would have been very close to 140mph mark if she would have hooked up all the way through the pass.

[Fluid]

Tyler, what did the prop look like after the run?



.

[RaceMechaniX]

A bladeless hub, that was it. Tool out the entire strut, bearings and wire drive.

[Kris Flynn]

That's awsome Tyler.

Are you guys using heat treated becu props or are you moving to the CoCr props for strength?

[RaceMechaniX]

Yes I was using heat treated props, but plan on using Stainless not CoCr in the future.

[B Neal]

Let's put one these in your boat, this picture was on a timed 135+ pass, had 138.2 last Saturday, did not take picture because boat blew off before the last light.

All you need is a "y" connector off your reciever battery.

Hopefully your cover is Kevlar or non CF

image.jpg

[Chris Harris]

A bladeless hub, that was it. Tool out the entire strut, bearings and wire drive.

Very Nice Tyler! Do you think that it started hopping because the prop lost a blade or the other way around?
It seemed to be pretty solid and then instantly had a bad hop going on. That kind of speed does crazy things to parts.

Chris

[RaceMechaniX]

Chris,

I believe somewhere near the 100-120mph mark the blades start flexing bad and the prop starts adding a vertical component causing the tail to lift. Once it comes out of the water the hard hit coming back in the water is pretty violent and breaks a blade. Then it hobbles on one blade bouncing till it generally breaks too. The data shows the RPM jumping from 56k loaded to 68k unloaded.

I tested several Stainless Propshop props that were representative of the diameters I need, juts not the pitch and they held up to very high RPM. So I know the direction we need to go.......

Brian, my riggers all lined with carbon so it would have to go on the outside. If you buy it I will tape it to the lid :-)

TG

[martin]

Tyler with our ic tethered hydros in the UK that are doing similar speeds we have to use props made from high tensile steel, otherwise the blades simply fold or come off. Nearly all of our props are cut from solid en24T steel (UK spec material), they are very strong & stiff in comparison with other materials.

[Tbauer]

Sick, sick speed

[jcald2000]

Tyler, be careful of the Propshop tethered hydro props, they are only rated for 30,000 rpm and I can testify they break at the hub above that!!

[martin]

Propshop tethered hydro props are cast stainless which on top line tethered hydros will bend or throw blades, all of the top line boats use home made props in high tensile billet form. Most props are made by the individuals them selfs & not some one that makes props for others, all close guarded secrets as with most props.

[Darin Jordan]

Looks like Late March is going to be very interesting!!

[RaceMechaniX]

Martin,

I spun the Propshop props to 58k with no problems, I am curious now what speeds/RPMs the tether boats run at. These seem more secretive than our SAW boats. I do plan on casting or machining my own props, but learning how to correctly design props in CAD will take some time. I consider myself a fairly good designer, but when I look at trying to parameterize props in CAD so I can scale/cup/rake it will take some time. I have friends with 5 axis CNC's who can cut these props, but it would be asking a huge favor so I want to do it right the first shot for a billet prop.

Are they are resources or websites for modern tethered hydros?

TG

[martin]

Tyler I know some of the very experienced engineers make jigs etc to machine their props out of but they still require lots of hand finishing. Guys like myself & many others that are self taught model engineers simply cut blanks & add spooning & twist the blades to get the blank followed by an awfull lot of hand finishing. I don't think any body in the UK is using expensive cnc machinery.