Vcat_2.0

[Dirk Jan]

Looking great! I really like the way you build as much as you can yourself :)

[modvp55]

Post 8 was an Art Carlson designed boat that was built by Starcraft.

[TheShaddix]

Finished the boat! Here are some pics of the final result. Ran it today. 6S on 2200kv w/ 2115 ABC props (about 52mm diameter) using swordfish 300A lite and sss 4082 motors. This is the first time I'm running such big props with this high kv, but the results were awesome. The torque was more than I could ask for. This boat is actually about the same weight as my hpr. The wooden shell was so optimized that it weighed very little in comparison to our old models (lighter wood selection, frameless design, less material overall, etc). The boat accelerated to top speed within just a second, no cavitation/slip at all. Now, there is still a slight problem with the bottom surface of this particular hull - not enough depth. It would hop a bit, but then settle at higher speeds. The stingers were set to be straight, no angle at all. Maybe that's the problem, but I believe that no angle is better overall, and adjustments should be made elsewhere. It had about 3 hard crashes today, no major damage other than the little wing/spoiler broke off due to being too thin on this model, but that'll be fixed and the bottom will be reworked. I will be focusing on the new hull now (the initial one in this thread). I will upload a video of the one I just got done building later on, still need to edit.

[kfxguy]

Looks awesome! I'm not hull engineer but I've been doing some experimenting with and airboat I built. I found that a deep tunnel works much better than a shallow tunnel. Also adding strakes to it helps even more. It might work even better if you put vents (or what everyone refers to as steps?) in the sponsons. Just some ideas. You could use some thin carbon strips you get from the hobby shop as strakes.

[kfxguy]

Never mind. I see the vents. Lol

[dmitry100]

TheShaddix, where did you get that black part that connects the wire to the rudder? https://photos.smugmug.com/Builds/i-.../DSC00004b.jpg

[TheShaddix]

TheShaddix, where did you get that black part that connects the wire to the rudder? https://photos.smugmug.com/Builds/i-.../DSC00004b.jpg

Got them on ebay in bulk, but the problem is those are metric, you have to then get a stainless 3mm threaded rod and custom make your own inserts that screw into those links. Then figure out a way to attach your flexible cables to the rod pieces (i use brass tubing).

There are the diagonal steps and also longitudinal channels, you can see them better in my first post. Not sure if those help at all, but we liked the look and decided to add them to every hull. I am itching to get the new boat built asap because it has about 3 times more depth at the bottom, plus both keels are sharp from back to front with no flattening out, so there is much more room for air and water to go through instead of being compressed and slapped by a flatter-bodied hull. You can actually hear the slapping sound when the boat runs at slow/medium speeds until it finally plains out and settles onto the keels, but then the air just gets squeezed under and the boat blows over around 80 mph.

I wish there were a super quick way to build a boat to test it out, then go back and make it look nice and all. Right now I am motivated but also a bit tired as I just finished this build and the results were semi satisfying, and it took a lot of work and time for all the custom little details. Thinking that I now need to go through the same exact process again back to back... But there is also something very special about making your own parts, even if the pre-made parts seemingly look more interesting and have better adjustment capability.

On a side note, for those who use the same pull-pull rudder system or want to try it, here is a tip! Make sure you have 0 angle in the cables! I did them straight through on this boat and that made such a huge difference in the turning radius, servo centering, more precise fine trimming, etc. You really don't want any angle on those cables from rudder to servo as that causes drag when going through the back plate. All the tension causes cables to press onto the tubing. Also, always add some oil or teflon grease into the tubes! The final result should allow the cable to be moved with no effort. I see a lot of mhz and hpr boats have a lot of angle and that is really the wrong way, even if it looks kinda cool. That's why you see some of those actually have separate parallel cables running near the tail that provide the function, while the angled struts are there just for the look.

[Fluid]

Make sure you have 0 angle in the cables! I did them straight through on this boat and that made such a huge difference in the turning radius, servo centering, more precise fine trimming, etc....I see a lot of mhz and hpr boats have a lot of angle and that is really the wrong way, even if it looks kinda cool....

These issues can largely be overcome through the use of a good quality digital servo. These have a very strong centering action and will overcome the drag problems that some boaters see even with a single pushrod. If there is room to have parallel push/pull rods that is fine. but it isn't always possible on some hulls.


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[TheShaddix]

For sure, but that's like fixing a badly built overweight boat by using larger motors and props. It'll get it going, but the problem is still there. If you have drag in the cables but the servo still centers it, i guarantee you that there will still be an offset when it returns to center, but it just won't be as noticeable. You can have a tiny bit of angle, but, ideally, parallel is better. I was referring to the crazy angles of some or most boats out there. I also use strong savox servos that have metal gears, digital, etc.

[dmitry100]

One thing I don't get is how to fix the slight "loose" slack that my Savox servo even if my pull-pull cables are super tightened. Theres a name for it... apparently RadioPost doesn't have this?

Not sure I'd want to spend that much more money for a servo though.

[dmitry100]

TheShaddix, I use something like this:

http://www.ebay.com/itm/Great-Planes...4AAOSwvg9XbfVl
combined with this: http://www.ebay.com/itm/DU-BRO-2135-...item1a162f5fe8
And then just solder my wire into the couplers. I'm hoping they'll hold up ok... but we shall see.

The swivel ball links I have are those black plastic ones, so thats why I wanted to maybe get some metallic ones. But can't find anything in 2-56 size.

For your application, have you tried using the 4-40 size couplers for your wire? Might save you some time:
http://www.ebay.com/itm/Threaded-Rig...YAAOSwOVpXbqKU

[Tamelesstgr]

Stingers look pretty heavy duty, how do you like them? Are they adjustable for the shaft length?

[TheShaddix]

TheShaddix, I use something like this:

http://www.ebay.com/itm/Great-Planes...4AAOSwvg9XbfVl
combined with this: http://www.ebay.com/itm/DU-BRO-2135-...item1a162f5fe8
And then just solder my wire into the couplers. I'm hoping they'll hold up ok... but we shall see.

The swivel ball links I have are those black plastic ones, so thats why I wanted to maybe get some metallic ones. But can't find anything in 2-56 size.

For your application, have you tried using the 4-40 size couplers for your wire? Might save you some time:
http://www.ebay.com/itm/Threaded-Rig...YAAOSwOVpXbqKU

I used to use those silver ones but like I said, the new metal ones are m3 thread size, there is nothing on the market that fits, so I bought a stainless threaded rod and just cut tiny bits off of it and customize my own. It has worked out so well this time that I really prefer it over anything else. Also, i am not too big of a fan of those plastic swiveling couplers mainly because of the look. I really like the metal ones because they are so nicely built and they are very cheap if bought on ebay from China.

I know what you mean by the slack in your servo. I have the same thing. It only happens when the servo is off. If you still have some play in the servo arm when the servo is turned on, then the problem is elsewhere. I use the cheaper savox servos for $25-30 and they work great.

Stingers look pretty heavy duty, how do you like them? Are they adjustable for the shaft length?

I really like those stingers, they are the 1/4" ones. I have never had one bend. Once you set them in place they don't move at all. The adjustment is done with just one bolt, and the support arm slides along the stinger. The only things I dislike about this stinger type are: the mounting holes are elongated, I would prefer just precisely drilled holes so it's easier to install; also the price is a bit steep at 40-45 each. i know that's nothing if compared to expensive german parts, but for someone like myself I really like to save on cost anywhere I can, that's why I started making my own servo and motor mounts. I thought about making my own stingers with those CF tubes they use for drones, but the amount of work involved is just too much and it would never be as tough as these ones.

[dmitry100]

Do you remember the product page or product name?

[TheShaddix]

Search for "M3 Aluminum Tie/Push Rod End Steel Ball" on ebay.