Eliminating Wah Wah

[CaptPJB]

Having read a ton of threads on the subject I am still not sure. Can the porpoising wah wah be eliminated by battery adjustment for COG and prop angle?

The threads suggest the fix is the offset rudder bracket from Kintec but there are also those that say they adjusted it out.

I have tried the extremes with battery placement from too stern heavy big wah wah to too wet running minimal wah wah with no definate conclusions.

Any help or comments appreciated.

Peter

[battlefury]

lay a windscreen wiper blade rubber across at the bottom of the hull. Somewhere when the surface starts to level out

[Andrewg]

Peter

3 things to check - sharpen the trailing edge of the sponsons - this is truly important; reset the strut and reset the cog.


1. if the trailing edge of the sponson is at all rounded sharpen it with a block and sand paper

2. Set the strut level ie parallel to the running surfaces, with the bottom of the strut about 1/8" above the bottom of the sponson.

3. Place the cells so the fore - aft balance point of the cat is 8.1-9.6" forward of the transom. The shorter distance for smooth water the forward for rough and wind

4. return to the strut and lift it a little more for more speed. Eventually this will introduce some instability and at that point drop it back to the previous setting.

It should run "lighter" and clean (less water spray) and handle well with better runtime)

Te measurements are start points, but measure when you make changes, it helps a lot.

[JackBlack26]

The only way I got mine to smooth out was to put a Castle 1512, 2650kv motor, lol!

[Andrewg]

Rafael

no doubt it would work - but that would be a slight change in weight distribution and increased prop lift at the higher rpm to hold the nose down.

The items I suggested also address problems in hull efficiency and their effect on handling potential. Just the basics to ensure the hull works as well as it can.

With the prop revving harder how does the boat run? It must give a pertty substantial speed bonus? and how is the cornering?

Captn - the rudder issue will influence the handling, in some cases it helps with turning others not. With the rudder in line with the prop, you will get advantages in terms of being able to steer very well both ways - however what needs to happen to keep things as efficient as possible is to make sure the boat turns with as little steering input as possible. ie sharp inside edges on the sponsons and the balance point a wee bit forward.

It will really depend on whether you are racing and the type of course ie ova or offshore. On the BJ26 an offset rudder actually helps the boat turn both ways by reducing the hull roll toward the outside of the turn. This hull has a much beeter sponson shape and beam to length ratio so its inherently more stable.

[CaptPJB]

Thanks for the tips Andrew as my main use is fun running I will "play" with it some more to try and eliminate the bounce before I try the offset rudder from Kintec.

Fiddling with a boat is half the fun.

Peter

[pyroM!KE]

I tried every cog adj, strut adj,prop angle I could think of..I never got mine out..I just put on a Kinetic offset rudder v2 and it went away! Just get the offset rudder and forget it..I wasted more runs trying to fight the issue and I was surprised it went away installing just the offset rudder..

[JackBlack26]

Rafael

no doubt it would work - but that would be a slight change in weight distribution and increased prop lift at the higher rpm to hold the nose down.

The items I suggested also address problems in hull efficiency and their effect on handling potential. Just the basics to ensure the hull works as well as it can.

With the prop revving harder how does the boat run? It must give a pertty substantial speed bonus? and how is the cornering?

There are 4 Geicos' in our group and we have all concluded that speed definitely helps the boat "smooth out". It still boced a bit when you hit a ripple or other boat's wakes but nothing like out of the box. Only 1 person runs an offset rudder and he didn't notice a difference. He runs the hottest motor being a 1415 2700kv on 5S. Insane RPM's and almost undrivable.

We also agree that the weight of 4S 2P helps the boat handle 100% better. Before installing the 2650, I could take any corner at WOT with the 3424 1800kv motor and the added weight of the LiPos. Having 200A of power on tap also helps everything work effortlessly and keeps temps way low.

With the 2650 I do let off the throttle a bit but still turn faster than with the 3424 at WOT without the boat getting out of shape. Its wild to see the boat turn away as its coming at you. It truly skims the water just like a hydro and is super responsive. The with of the boat makes it near impossible to roll when set up right. My battery CG went from 8" from transom forward with the 1800kv motor, to 9 1/4" with the 2650. I have yet ti find the limits of the hull, but I'm not as experienced with boat design and I'm over all new to FE boating.

Bellow is a video of how the boat runs. I havent been out to run it again since but will get an updated video soon. In the video I set the timing to 2* but later went up to 15* and there was a substantial speed difference from that video, with temperatures still being in check. Everyone who has seen it run with the 2650 has had nothing but admiration for the boat as a whole and the speeds it can handle.

http://www.rcgroups.com/forums/showpost.php?p=17548929&postcount=4218

[Andrewg]

JB great stuff

[battlefury]

There are 4 Geicos' in our group and we have all concluded that speed definitely helps the boat "smooth out". It still boced a bit when you hit a ripple or other boat's wakes but nothing like out of the box. Only 1 person runs an offset rudder and he didn't notice a difference. He runs the hottest motor being a 1415 2700kv on 5S. Insane RPM's and almost undrivable.

We also agree that the weight of 4S 2P helps the boat handle 100% better. Before installing the 2650, I could take any corner at WOT with the 3424 1800kv motor and the added weight of the LiPos. Having 200A of power on tap also helps everything work effortlessly and keeps temps way low.

With the 2650 I do let off the throttle a bit but still turn faster than with the 3424 at WOT without the boat getting out of shape. Its wild to see the boat turn away as its coming at you. It truly skims the water just like a hydro and is super responsive. The with of the boat makes it near impossible to roll when set up right. My battery CG went from 8" from transom forward with the 1800kv motor, to 9 1/4" with the 2650. I have yet ti find the limits of the hull, but I'm not as experienced with boat design and I'm over all new to FE boating.

Bellow is a video of how the boat runs. I havent been out to run it again since but will get an updated video soon. In the video I set the timing to 2* but later went up to 15* and there was a substantial speed difference from that video, with temperatures still being in check. Everyone who has seen it run with the 2650 has had nothing but admiration for the boat as a whole and the speeds it can handle.
http://www.rcgroups.com/forums/showp...postcount=4218

I second that. 4s2p is well suited for the MG. I tried a couple of setup from 4s1p, 6s1p and 4s2p. 4s2p 5000mah per lipo on 2200kv being the best.

[wiskers]

I love your videos. So if your runnibg a 1512-2650 motor what esc do you need to make this work.

[TheShaughnessy]

Rafeal, what's up man, i made it over to OSE finally after Tony, told me to get over here. I met him last weekend at legg lake. Why doesn't the group ever run there? Seems like it would be the closest to you, its an hour and a half for me ( but I'll drive). I need to see how far away Hanson damn is. I don't have a canopy for my MG right now so that is somewhat of an issue.

As for the Wah Wah, i never got mine out with the stock set up with 4s, didn't really run it that way much, 5s with the stock motor for the most part. I now have the ul1 2030 kv and i love it. Have it paired up with a T 120 and a m445. This hull definitely is asking for more power to keep her riding flat.

I do not have the Kinetec offset rudder but i did offset my rudder and it was free. You could do yours for 4 bucks in hardware from Osh. I believe the kinetec one offsets it 2 inches where I only made it over an inch, but it rides nicely and i don't feel as though i lost anything in the corners, i actually have epa/servo through or whatever it is set at about half of what it can do and feel like i could dial it out a little more, but i just do that with the wheel.

4s2p.... its a no brainer man. Trying to get this boat going fast and stable is a lot easier with some added weight. Why add useless weight though when you can add some extra cells and get more run time and more amperage on tap.

Did i see 2700 kv on 5s? What the hell are you guys thinking? You can actually spin the prop with out cavitation? Does he have a teflon liner in his stuffing tube? How does that not melt. What prop is he spinning a x 437/3? smaller?

I no longer use those parallel connectors though. I switched over to 5.5 bullets and eliminated the wire so its just two males soldered to a female and vice verse. They seem to work nicely.

The video is my first run with the ul1 motor, I have since dialed in the ride much more. I now run the batts about an inch forward from the end of the stock trays.

http://www.youtube.com/watch?v=FafgQb7cP5M

Another added benefit of the offset rudder is it makes greasing your flexshaft easier. You no longer have to remove the bolts to get it out of the way. I also felt like having the rudder in the prop wash was taking from the propulsion, that may be completely false and probably is, but I didn't like it inline.

[ron1950]

us=1 motor seems to be the best speed for the bucks atonly 59 dollars.....

[JackBlack26]

I love your videos. So if your runnibg a 1512-2650 motor what esc do you need to make this work.

I'm running a Turnigy 180A which doesn't break a sweat.

[JackBlack26]

Rafeal, what's up man, i made it over to OSE finally after Tony, told me to get over here. I met him last weekend at legg lake. Why doesn't the group ever run there? Seems like it would be the closest to you, its an hour and a half for me ( but I'll drive). I need to see how far away Hanson damn is. I don't have a canopy for my MG right now so that is somewhat of an issue.

As for the Wah Wah, i never got mine out with the stock set up with 4s, didn't really run it that way much, 5s with the stock motor for the most part. I now have the ul1 2030 kv and i love it. Have it paired up with a T 120 and a m445. This hull definitely is asking for more power to keep her riding flat.

I do not have the Kinetec offset rudder but i did offset my rudder and it was free. You could do yours for 4 bucks in hardware from Osh. I believe the kinetec one offsets it 2 inches where I only made it over an inch, but it rides nicely and i don't feel as though i lost anything in the corners, i actually have epa/servo through or whatever it is set at about half of what it can do and feel like i could dial it out a little more, but i just do that with the wheel.

4s2p.... its a no brainer man. Trying to get this boat going fast and stable is a lot easier with some added weight. Why add useless weight though when you can add some extra cells and get more run time and more amperage on tap.

Did i see 2700 kv on 5s? What the hell are you guys thinking? You can actually spin the prop with out cavitation? Does he have a teflon liner in his stuffing tube? How does that not melt. What prop is he spinning a x 437/3? smaller?

I no longer use those parallel connectors though. I switched over to 5.5 bullets and eliminated the wire so its just two males soldered to a female and vice verse. They seem to work nicely.

The video is my first run with the ul1 motor, I have since dialed in the ride much more. I now run the batts about an inch forward from the end of the stock trays.

http://www.youtube.com/watch?v=FafgQb7cP5M

Another added benefit of the offset rudder is it makes greasing your flexshaft easier. You no longer have to remove the bolts to get it out of the way. I also felt like having the rudder in the prop wash was taking from the propulsion, that may be completely false and probably is, but I didn't like it inline.

Glad to finally se you over here!
Legg Lake is a bit to serious for me from the stories I hear. I run for fun and never intend on racing, though I will bet my NAMBA card soon so I ca run at The Prado since its just 5 minutes down the street from me.

Boyd , is the name of the Gent. that runs his 1412 on 5S with a 38mm prop, I believe. You may see him at Legg Lake since he just got his key. Last time he came to the Dam he mentioned he had been spending quite a bit of time over there. He has a liner but remember it's Teflon and greased so the odds of it melting are zero to none.

Here is a video from last week. I went back to the 3424 1800kv Castle out runner with an x445 prop with only 2, 2S packs and still no bounce. Well, it bounces 3 times coming out of each corner, but not at full throttle. I still say it's all in the setup and I will not offset my rudder. It doesn't need it. The electronics run very cool so I may move up to an X447 next.

http://www.youtube.com/watch?v=x-z18v-PFac