Darin's TFL HOBBY 34" Carbon Cheetah Build

[kfxguy]

Thanks... Those are factory Pro Boat BJ29 V3 ESCs...

http://www.proboatmodels.com/Products/Default.aspx?ProdID=DYNM3875

I know lol

[kfxguy]

Pretty sure Dynamite is buying from Hobbywing. Why not? They're pretty good units. The dynamite cooling block is better than the Seaking block IMO.

Yes, yes and yes and it looks better too

[Tamelesstgr]

Seeing the quality and craftmanship of some of these builds makes me realize how much I have yet to learn!

[Darin Jordan]

In preparation for trimming the length, I filled each sponson tip with approximately 20cc of epoxy and milled fiber.
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Also made a modification to the TFL struts. Added holes to allow lubricant to be injected into the strut and flex. Since you have to remove the motors to get the flex shafts out, I consider this a necessary modification to help maintain race day sanity!

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[ray schrauwen]

I'm surprised you are giving the captivated drives a go but, I know you will do them justice. Did one stub come with left hand thread like some I have in 4mm?

[Darin Jordan]

I'm surprised you are giving the captivated drives a go but, I know you will do them justice. Did one stub come with left hand thread like some I have in 4mm?

I'm putting this together with everything that TFL sent me. I asked for a complete kit and this is what it is. I think it's pretty nice stuff!

These drives have a captured propshaft with a squaredrive on the prop end, and fit into couplers at the motor. The motor couplers are opposite threads for opposing rotation. The flexshafts are opposite as well.

I'm not a huge fan of burying the flexcables this way, but honestly it's not that different than an OPC setup, and with the lubrication ports, keeping them up to stuff shouldn't be an issue.

Hopefully I don't break a shaft anytime soon. Not sure where I'd get replacements. It might be time for me to buy my own broach setup and also a square-drive die for my 20-Ton press...

[Meniscus]

Darin, an operable question if you don't mind: are you planning to run the twins turning out or in?

[Darin Jordan]

Darin, an operable question if you don't mind: are you planning to run the twins turning out or in?

Good Question and one that I've been researching. Never having run a twin before, I've only heard differing opinions... Something about inwards for SAW, outwards for oval/Offshore...

I'm open to opinions/suggestions on this one. At this point, I'm not convinced it makes much of a difference, but again, I don't have any first-hand experience with Twins...

[srislash]

Good Question and one that I've been researching. Never having run a twin before, I've only heard differing opinions... Something about inwards for SAW, outwards for oval/Offshore...

I'm open to opinions/suggestions on this one. At this point, I'm not convinced it makes much of a difference, but again, I don't have any first-hand experience with Twins...

It really seems to depend on the hull Darin. On my Shocker hull it NEEDED outward for corners. All the difference in the world. But then on my PB Geico twin it corners fine either way but bounces terribly with them outward.
Most likely you will try either way and see though.

[Meniscus]

Darin, I personally believe that it has to do with the dihedral employed on the steps combined with the size of the prop and the depth of the stinger. As you already know, torque forces come into play depending on the way the props are prepared. That could also be a source of discrepancy between the ride attitudes experienced. I've also read in German forums that the width of the wedge rudder plays a big part for ovals, but I don't have experience with that factor for twins, at least not enough to make an objective observation. By the same token, I would be inclined to believe that the aeration of the prop also plays a part with certain hulls in relation to the tunnel area as-well-as how the air comes off of the steps. That would also explain why dihedral may make a more pronounced effect.

As a side note, you may find some useful information with those who run twins in riggers in the Nitro world. They may be able to shed some light on the subject and the forces at play. Whatever they have noticed would of course be magnified or compounded with electrics. That may be a source of objective information regarding the props themselves as-opposed-to other effects inherent to the tunnel or the steps.

[785boats]

Something like this you mean, Meniscus?
Some very interesting discussion here.

http://www.intlwaters.com/index.php?showtopic=20987

[Darin Jordan]

Moving along....

Starting to reassemble now. Going to assemble and get this all setup sans-paint so I can fully test it out before I commit to a paint scheme. I've been told by some that the sponsons need to be modded for it to work correctly, but I'm going to just block-sand them to true up the ride pads and give it a go before I commit to any changes.

Started installing the struts. Left strut lines up well, but the right strut was angled out slightly, so I block sanded the transom on that side until it came back inline. I think I have them about right now.

I also opened up the holes in the mounting pads a tad. I want to be able to make slight adjustments in the height and rotation of the mounting.

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[flraptor07]

Darin, Some of those Cheetah hulls need the mod and some don't. On the ones that do it's the rear ride pad, you can tell by putting a straight edge from front to rear across the ride pads. If it's one that needs the mod you will see that the rear ride pad is not the same angle as the rest of them. It will be higher at the trailing edge acting like a trim tab and pushing the nose down. The mod is to build up the leading side of the ride pad and gradually taper it back to the same height as the trailing edge to make it match the contour of the ride pad ahead of it. Scott "Tiqueman" was the one that came up with this mod, I did it to mine and it was night and day difference. I think you saw a video of how nice mine runs and corners.

[Darin Jordan]

Have the business end about wrapped up. Shortened the flex cables and mounted the struts last night. Used a little Black RTV on the mounting surfaces to seal them to the transom.

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Mounted the motors, ESCs and steering system. I used a bit of double-back ESC tape on the bottom of the servo to keep it from shifting around. TFL just uses a ZIP-Tie to hold the servo down in the recess. The Tape made everything solid.

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Need to come up with a battery mounting setup. For now I think I'll just use Velcro until I know where things need to be. Ultimately I'd like to install the sliding battery trays that the SAW Cat guys use.

[Rafael_Lopez]

Looks great Darin. I cant wait to see it run!