16" Twin Cat Build

[j.m.]

Hey guys, just started this little bugger two days ago. 16" length, 5.25" beam. Based off the 30" cat plans Lomdel made.

Going to be a twin drive, probably 380 brushless motors, most likely 2s lipo. Straight shafts, 1/8" diameter.
Pencil pic shows angle of shafts... Good? Too much?

[j.m.]

Bottom sheeting

[kennyrach]

:w00t: Nice looking boat m8

[j.m.]

Thanks!

[lomdel]

Should be a fun boat! Keep it up and keep the pics coming. Make sure the sponson bottoms are level and parrallel before sheeting the deck. How are you going to finish (seal, paint) it?

[Simon.O.]

16"and twin 380 BL ??? I am watching this !!!!

The drive line angle could be ok and I hope you will tell us if it is not.

I am soon to do a 18-20" twin that will be wrapped in a Cat-Hydro hybrid hull. Bless the Europeans thier forward thinking.

For twins on this size hull the 380's will rock and if you go for a long 380 then you are up towards a 540S for power but less torque.

Keep the props small and deffo counter-rotating.

When I do mine I will use the Mystery Outrunners+30A esc combos and get some Graupner props in the 27-30mm range. Left and right are mandatory if all the reading that I have done is correct.

I will watch this with enthusiasm. :w00t:

[j.m.]

Thanks for the support, guys! And yeah, for sake of easy driveline assembly and parts availability, i'll be using these motors>
http://www.hobbycity.com/hobbycity/store/uh_viewItem.asp?idProduct=4201&Product_Name=HXT_2835_(380S)_2700kv_Brushless_Inru nner
On 3s, or the 3900Kv if I go with 2s. Hull is perfectly straight (much to my surprise), and will be epoxied from the inside and fiberglassed on the outside. It's 1/32" balsa, so the epoxy will seep into it and make it nice and hard. 3 layers of .75 oz. glass on the outside, with 4 on the sponsons should make them REALLY strong.

[j.m.]

Okay, slight change on the driveline setup. No more 1/8" shaft, can't find props. (other than a x430 and x430r which will need to be balanced and sharpened... (I haven't ever done that))

Now using the cen 4mm stainless shafts with ose 1/8" to 4mm motor couplers, and Graupner 31mm plastic props. These seem like they'll either be a perfect size or slightly too big.

Assuming 4.0v fully charged per cell, i'll be running 12v with 2700Kv motors, or 32,400rpm unloaded. Just right. I'll suppose they will have similar torque to a brushed 540... (Simon, this is where you come in) Do you have any motors that run this kind or rpm and run ~35mm props?

[lomdel]

Pics of progress, mate, pics, lots of pics... We need pics!

[Simon.O.]

Okay, slight change on the driveline setup. No more 1/8" shaft, can't find props. (other than a x430 and x430r which will need to be balanced and sharpened... (I haven't ever done that))

Now using the cen 4mm stainless shafts with ose 1/8" to 4mm motor couplers, and Graupner 31mm plastic props. These seem like they'll either be a perfect size or slightly too big.

Assuming 4.0v fully charged per cell, i'll be running 12v with 2700Kv motors, or 32,400rpm unloaded. Just right. I'll suppose they will have similar torque to a brushed 540... (Simon, this is where you come in) Do you have any motors that run this kind or rpm and run ~35mm props?

Jon if you are still open to shaft and prop ideas look at this selection of props
http://www.cornwallmodelboats.co.uk/acatalog/propellers_surface.html

The motors you are looking at from HK will be fine in a 16 hull. My suggestion is to keep the prop small. 31mm would be max for me.
The Graupner props come in 1.2, 1.4, 1.6 pitches.
I have read that the 1.4 is not quite that and may be a bit less, this is good as it will not load you up.
I suggest a 40A esc each side.
Prop light, check temps then up prop.

[j.m.]

I can cut the 31's down. I'll order two sets and cut one to 30mm, and the other set to 28mm.

Cornwall seems like a good place, but I'd rather not pay $13 for two plastic props.

Edit> About the progress pics... There are none. I'm out of CA. I have the outer sheeting on the right sponson done, but I'm sure all of you know what that looks like.

[ace028]

Updates?