RCU 8th Scale Brushless Hydroplane Build

[kcpasco]

Here are a few new pictures. As you can see I have the turn fin mount in place and the turn fin turn-buckles in place. They are adjustable so if I change my turn fin angle I can adjust the turn-buckles as well. They are also break-away along with the turn fin.
Also got the rear wings mounted, the next pictures will show the rest of the wing brackets as well. As you can see in the other pictures I will be mounting the servo in the engine well wall to continue my theme of hiding as much as I can and keeping everything clean and organized. In the one picture you can see how the batteries will fit right in the side compartments on both sides of the motor. Nice and clean and organized. I decided to go with the castle 240 high voltage as I got a great deal on a new one.

[icelert]

It sounds like you didn't have the esc timing set optimally for the Scorpion. If you were using the same timing as the Neu, that might be the reason.

I have been running a Scorpion HK4035-800 on 8S1P on an X457R on a 59 inch long 1:6 scale hydro without any heat issues. Speeds were in the low to mid fifties.

Don't get me wrong though, Neu's and Scorpions to me are apples and oranges. All I am saying is that the Scorpion can be a viable option if setup correctly.

Here is a video I made to show what I mean,

http://www.youtube.com/watch?v=gQI3flToaS8

Bryan

[kcpasco]

Dave you make a great point.... I actually have been keeping that in mind just as much as I have keeping everything neat and organized. Everything is very easy to access and change as well as being hidden away. The radio box has all wires and water lines built into the wall so I can plug and unplug on both sides. The batteries will easily fit in their compartments and have a latch on the front to lock them in and the wire will be right there to plug and unplug them. I just finished the aluminum servo mount bracket that will fit on the inside of the hole and has been tapped for the servo to bolt on. Very easy to unbolt and bolt a new one in as well. Everything is very easy to access and change out if need be. But very good point that should always be a goal to keep everything accessible.

As far as the skid fin goes yes it is breakaway and the turnbuckles attached to it are also break away, but the buckles break away in the middle with a nylon bolt in each so one side will stay attached to the boat and the other side will stay attached to the skid fin. To put it back together just move the skid fin back down where it goes and put two new nylon bolts in the turn buckles and back in business.

Below I put pictures of my wings mounted and almost done just have to do the adjustable mounts on the back of the top wing so it is adjustable and they will be done. They are held on at all attachment points by nylon bolts as well so they will come off during a crash and not hurt the boat hopefully.

[kcpasco]

Also I dunno if anyone can see in any of the pictures a couple of us are building scale trailers to go with out boats. The nitro guys almost all just have box stands that their boats sit in. We got the ok to make these as long as we make a prop guard that attaches to the back and covers the prop in the pits. That will not be a problem. The trailers will look scale and tilt like the real boats as well. I even added drawers into my trailer that fit all my batteries and other spare parts. I think they are a nice addition to the boats. Should be cool when done, I will post some pictures of the trailer progress here in the next few days.

[kcpasco]

Ok guys I have a dilemma and need some advice. I was planning on running two 4s 5000mah in series making an 8s 5000 mah setup which is what we will be running in the club. I know that we will be doing some milling then 5 lap races. When Bob and Rob were testing this setup they got almost 2 minutes runtime and had 17 percent battery left meaning they could get maybe another 30 seconds before they were completely dead. This is cutting it very very close for a race runtime. So I had planned on running a separate receiver lipo, a 2 cell 2200mah with a BEC to regulate it down to 6v. I just noticed you can buy high voltage BECs I didnt know those existed, they handle up to 40volts, so I can run those off my main batteries and eliminate the need for a separate receiver pack. Since I am already worried about runtime though would adding that draw enough current off the batteries to hurt my runtime even more? I know that when I use to run lipos in my 12th scale for my receiver pack I ran a 900mah 3cell and I could run it for a full day of running a nitro, throttle and steering servos, and I would go to charge it and it would almost have a full charge still. So maybe they do not pull enough current to make a difference. Just wondering if anyone knew anything on this subject or had an opinion.

[kcpasco]

It was Bob and Rob that tested the scorpion. I know they ran the castle 240 on its stock setting to get a direct comparison to the NEU. I know that even the 7th scale guys run the scorpion so I am sure it works it must just be the settings or something. As far as I have heard so far the scorpion will most likely be an option for the RCU electric guys, I already have the NEU and was more impressed with it so I will just stick with it. Just a guess but maybe the scorpion would do better on higher voltage? I am not sure but maybe that will help it work more efficiently I dunno though.

[kcpasco]

Yeah I will probably just run a receiver pack. I have had pretty good luck with BECs to this point. I will have to have one either way, either running a low voltage one on my receiver lipo or a high voltage on my main batteries to run the receiver off of them. My receiver can take up to 9volts but my servo is only rated at 6v.

[kcpasco]

Ok here are a few pictures of the trailer with the boat on it. As you can see it tilts like the real ones as well. I forgot to take a picture with the drawers out but the drawers pull out and the batteries are stored in there along with other spare parts. Since I will be doing the Oh Boy Oberto I made the trailer to look just like the Oberto trailer.

[kcpasco]

Yeah I am very optimistic we can get what we need out of the batteries I have a sinking feeling it may be close though. I hope there is room to spare though. I never paid attention you have the 6.6v are you running it on a high voltage servo or standard? I know my receiver can handle the extra voltage but Im worried about my servo. I will be running 1/4 scale servos but its only rated to 6v and dont want to fry it. I dont mind running a BEC its what I am use to. But eliminating extra wires is always a good thing.
Thanks about the trailers we are pretty excited about them. Just a fun little touch and fun to do.

[kcpasco]

Got my boat weighed today with everything in it and on it. Still rebuilding the cowling and obviously its not painted yet so minus cowling and paint I was still just under 15lbs. That is much heavier than I wanted to be but I guess electrics are heavier than nitro boats right? I mean our batteries, the two 4s 5000 mah weigh right around 2 and a half pounds by themselves. I am going to try a few things to cut a little weight out and once I add cowling and paint I want to be at 16 or under. I will maybe build another boat next season and try and get it lighter but I think I will be happy with 16lbs this year.

[kcpasco]

I am looking at a couple options to get rid of a little weight. One thing I have a few 1/4 scale servos and I had planned on running them, however they are big and heavy, so I may go with a standard sized servo. If I do I can either go with a high voltage servo and that way I can just run a 2s lipo with no BEC, and the high voltage servo puts out over 400 Oz of torque which is wayyyyy more than I will need. Or there is a cheaper waterproof servo Im looking at that puts out well over 300 oz which is still even more than the 1/4 scale servo. If I go with this second option I am thinking about getting one of the High voltage BECs and then I will not need to run a receiver battery pack at all. I can cut about half a pound out of my boat by going with this option. I am also thinking about building brand new wings and canards and so on out of balsa and carbon fibre to cut down on weight.

[Fluid]

The Scorpion motors lack the efficiency of most inrunners. Their US distributor tells me that they have core saturation above 100 amps, meaning that most of the extra electrical energy they pull turns directly into heat. Plus they are difficult to cool in boats. For sport applicaitons they work well, I run an HK4025/6 in my 6S cat for sport purposes and at amp draws below 110 it works well. Prop it too high and the heat soars.


.

[kcpasco]

I went ahead and ordered the high voltage BEC and a standard high torque servo. I will have to test this setup and see if I can get the run times I am needing but I am hoping that will not be an issue.
I will probably be waiting on this stuff for at least 3 weeks so instead of testing then painting after I will probably go ahead and start painting and just test after its painted. Since I am already heavier with this boat then I wanted to be I am planning on running this boat and as soon as its done starting to build another one shooting for a lighter weight.

As far as this boat goes everything is mounted except the cowling and the cowling is the next project. The pictures show the boat with everything on it, but the cowling will be changing, I am cutting the cowling off and rebuilding it from scratch cause the cowling that came with these boats does not look close enough to the real boat to fit my liking. I will build it out of foam, then glass it and pull a mold off it most likely. I may lay up the cowling with carbon fiber and make it thin as I can replace it if it gets damaged. Oh also as you should be able to see in the pics we went ahead and made our own spars out of carbon fiber as the spars that came with the boat were not the correct tear drop shape like the real boats.

[kcpasco]

Yeah I assume that is the issue. I already have the NEU so thats what I will run as I like it very much and it runs great. The scorpion is going to be allowed to run in the club and I am sure it will do great as well. We will most likely add a few more, we want to have as many options available to people as possible while keeping the field even.

It sounds like you didn't have the esc timing set optimally for the Scorpion. If you were using the same timing as the Neu, that might be the reason.

I have been running a Scorpion HK4035-800 on 8S1P on an X457R on a 59 inch long 1:6 scale hydro without any heat issues. Speeds were in the low to mid fifties.

Don't get me wrong though, Neu's and Scorpions to me are apples and oranges. All I am saying is that the Scorpion can be a viable option if setup correctly.

Here is a video I made to show what I mean,

http://www.youtube.com/watch?v=gQI3flToaS8

Bryan

[kcpasco]

Ok guys well I have everything else I need to complete the boat ready to run on order and should have everything within the next 3 weeks, some coming from China. So my plan is to break the boat down, already started, and start on body work priming and painting, as well as polishing up all the fabricated parts before they go back on the painted boat. So I will update in a few days when I actually start getting paint on some stuff... Right now I am deciding if I want to paint, then clear and put decals over the clear. I do my own vinyl graphics so I can always change them and update them to what the current Oberto has if I put the graphics outside the clear.