Delta Force 35" First test, Fail!

[Fluid]

All my 3/16" cable drives run in 1/4" OD brass with no Teflon and no grease - I use automotive hypoid gear oil. Smaller tubing just promotes excess friction. One boat has run for two plus years in many dozens of heats in a high power 4S application - same cable, same brass tube. In fact I have never replaced a brass stuffing tube for wear.

There should be no more than a 5/8" gap between the end of the coupler and the start of the stuffing tube. Much more means cable whip and the results above. Here is the 1/4" tube and the small gap.

[6sHyper]

What prop you running? Looks like you need a bit more. Lots of cavitation!

Dont take this the wrong way cause i dont know if rc boats are different or what but i do know on a real boat, since i'm a wakeboard boat wholesaler and rider that you get cavitation when the prop is too big, because they push too much water there becomes an air pocket between the hull and prop, thats what cavitation is, so for rc boats is this different or what??

i would have thought starting with an x445 would be alittle on the big side for a starting point no??

[LarrysDrifter]

Fluid,where did you get that motor mount? I have a PTSS45 hydro and would like to use the nitro hull mounting holes.

[rearwheelin]

Check out post 69 of his build thread !! He has no solid support on the front of his stuffing tube......Has only spray foam with a ply containment......Millzee , I would re-do the whole stuffing tube setup ! The foam gave way to the forces and let the cable start to gradually gain whipage momentum !! You need a stout anker at the front of your stuffing tube , or else !!!!.................................Hello !!!!!!!!!!! am i preaching to the quiore or what, someone please let me know that I have no point , please.......am I wrong or is everyone else right......ha ha ha

[keithbradley]

Dont take this the wrong way cause i dont know if rc boats are different or what but i do know on a real boat, since i'm a wakeboard boat wholesaler and rider that you get cavitation when the prop is too big, because they push too much water there becomes an air pocket between the hull and prop, thats what cavitation is, so for rc boats is this different or what??

i would have thought starting with an x445 would be alittle on the big side for a starting point no??

An air pocket would be ventilation or aeriation. Alot of people call ventilation cavitaion, but they are really 2 different things. Cavitation can be caused from a prop that is too small to efficiently move a hull... meaning it doesnt get enough undisturbed water because the boat that its attached to wont move fast enough to supply it. A poorly sharpened prop can also cause cavitiation by creating the same type of low pressure area, only because it is disturbing a larger amount of water that is not being used to propel the boat.

[millzee]

thanks for the replys and info, so, when rebuilding I will use the 9/32 brass with teflon tube, give it better support from tramsom to coupler and only leave a very small gap between the coupler and stuffing tube with a support at the end of the tube. Am I on the right track?

[Raydee]

I gave my opinion on the youtube vid....get rid of the teflon. Run straight brass tube and you don't have to worry about the liner heating up, melting and ripping the stuffing tube out of your boat. I know guys will say they run teflon without ever having a problem and they probably haven't but I know plenty of guys that have had problems running teflon including myself and I will never run it again.

[millzee]

I gave my opinion on the youtube vid....get rid of the teflon. Run straight brass tube and you don't have to worry about the liner heating up, melting and ripping the stuffing tube out of your boat. I know guys will say they run teflon without ever having a problem and they probably haven't but I know plenty of guys that have had problems running teflon including myself and I will never run it again.

And I thank you for your advise, I am looking for runtime, would you say the brass only would be ok to use and if so, the guy's have said to use the 1/4" over the 7/32" but no one has told me or sent me any links to how I would set it up, is it as simple as running the flex through the brass or are there any tips/tricks that are needed? I'm not trying to get on your nerves, I just simply don't know these things.

[Fluid]

Fluid,where did you get that motor mount?

South River RC Boats.

http://southriverrcboats.com/shop/category_Motor%2520Mounts/Motor-Mounts.html?sessid=JDKISZhOH0IquqQ5IK0OawQEzWtZ4C7CtlpuFUFxaNVY8kOfkvjqxc5YL2HGvnG6&shop_param=cid%3D%26

.

[marko500]

After listening to Raydee and reading Fluids posts I did my last build without teflon and used the 1/4 tube for the .187 flex as recommended. I used a small piece of 7/32 tube about an inch long as a bushing at the coupler end of the 1/4 tube, also a small piece of shrink tube as a water seal between the tube and the coupler. I was nervous at first because the flex felt "sloppy" in the tube but it has run flawlessly with very little drag. All my builds from here on will be setup like this without the teflon liner. Also agree that you need to redo the tube and loose the gap between the tube and coupler.

Mark

[rearwheelin]

Check out post 69 of his build thread !! He has no solid support on the front of his stuffing tube......Has only spray foam with a ply containment......Millzee , I would re-do the whole stuffing tube setup ! The foam gave way to the forces and let the cable start to gradually gain whipage momentum !! You need a stout anker at the front of your stuffing tube , or else !!!!.................................Hello !!!!!!!!!!! am i preaching to the quiore or what, someone please let me know that I have no point , please.......am I wrong or is everyone else right......ha ha ha

....bump

[marko500]

Check out post 69 of his build thread !! He has no solid support on the front of his stuffing tube......Has only spray foam with a ply containment......Millzee , I would re-do the whole stuffing tube setup ! The foam gave way to the forces and let the cable start to gradually gain whipage momentum !! You need a stout anker at the front of your stuffing tube , or else !!!!.................................Hello !!!!!!!!!!! am i preaching to the quiore or what, someone please let me know that I have no point , please.......am I wrong or is everyone else right......ha ha ha

Sorry went to mention that also in my post. I have to stop trying to think to much or post before my morning cup of coffee. I think the whole stuffing tube area needs to be redone. Still did better then some of my first runs!

Mark

[LiPo Power]

Was your flex turning easyly before test run?
I take that you did lubricate flex with grease before your first run
IMO, space between bras tube and coupler was to big. 30.000 rpm can with no problem do that right where the flex will get some room to unload the rotation force. Also, you may need to try few other props just to see the big diference.
Plese drive straight lines at first with not too much turning left and right close toogether if possible so the boat can unload and get on plane. That will also help proper cooling circulation. You need cooling when testing! Do short runs, check temps often and allow the components cool down well between runs. ( been there done that )....
Other than this, you have wicked boat and can not wait to see another video with more testing .....
Cheers
Robert

This is a link to my first test of my first build, it's also the first time I've driven an rc boat so I guess I got a few things wrong.
http://www.youtube.com/watch?v=tK0ITqCORmQ

[millzee]

I'm just putting some pic's up on the "digout" on the build thread so you can see what I was trying. I now seem to think the 1/4 tube with no teflon sounds good, how do you attach the 1" of 7/32 as the bushing?

[millzee]

Was your flex turning easyly before test run?
I take that you did lubricate flex with grease before your first run
IMO, space between bras tube and coupler was to big. 30.000 rpm can with no problem do that right where the flex will get some room to unload the rotation force. Also, you may need to try few other props just to see the big diference.
Plese drive straight lines at first with not too much turning left and right close toogether if possible so the boat can unload and get on plane. That will also help proper cooling circulation. You need cooling when testing! Do short runs, check temps often and allow the components cool down well between runs. ( been there done that )....
Other than this, you have wicked boat and can not wait to see another video with more testing .....
Cheers
Robert

thanks mate, that really helps, and yes I did grease it all up b4 running and in between the two runs. I've ordered a x642, I suppose this might show just how much I don't know but I was hoping it'll lift it a little more, is this correct? I have a few props that need balancing and sharpening (which I need to learn how to do) a x440, x442, x447, x448 and the only other sharppened and balanced I have other than the x445 is a x450.