Cat Prop Spacing

[Mike W]

With the majority of newer cat designs using stingers as in full scale versus tubes and struts in the tunnel how does that difference in prop spacing and location affect performance and tunnel aerodynamics?

Obviously the larger difference in load when turning with stingers would be a negative but other differences aren’t as clear to me?

[srislash]

I think the theory is that most of the weight is low in the sponsons. This is what I’ve subscribed to in the past. But... I am about to mount motors on the tunnel and run struts out back on a R-42. I have already built an R-42 in the aforementioned format so I’ll be able to tell you definitively next spring.

For kicks, the first build: https://youtu.be/uuP1Bi1eISk

[CraigP]

Shawn, BlownAway blows me away! Really looks like a kick to run. Great job on that boat!

[srislash]

Shawn, BlownAway blows me away! Really looks like a kick to run. Great job on that boat!

Craig my good man, how are you pal?
Yes but as nice as BlownAway is to run I think I can shave 4-5lbs off the next one.

[CraigP]

I’m great! Been running the big boat, GP55 this summer. I started building and tuning the motors.

I was thinking watching it run, that weight might be contributing to the excellent handling and keeping it on the water. Will be interesting to see, that’s a lot of weight savings!

[CraigP]

I was disappointed that my twin hydro didn’t have that dual engine sound... They are in perfect sync, you couldn’t even tell by the sound there are two motors in there. I just love the sound of your boat, it adds to the excitement!

[Mike W]

Craig my good man, how are you pal?
Yes but as nice as BlownAway is to run I think I can shave 4-5lbs off the next one.

Handles very well what's a R42? Current setup is what? 4-5 lbs. is an awful lot how?

[srislash]

Handles very well what's a R42? Current setup is what? 4-5 lbs. is an awful lot how?

Well this new one came direct from Andy(owner of AC Boats) and has no rails and a little mod for the occasional hooking some complain of. So the lack of rails will be some weight. BlownAway has Castle 1717’s in it so they are hefty and also tend to eat amps. So I run 6s2p per side. The next hull will run TP 4082’s on 10s and I’m going to try to keep it light.
I can always add weight right Craig? Lol

[CraigP]

Of course! I got some 96gram lead weights I velcro’d in the UL-1. It needed some weight to help keep it planted good in the turns... TP motor, eh? I’m gun shy on those. I got a 4082 2230kv that wouldn’t run the Littl’ GP55 on 4s, would go into thermal limit trying to get thru turn 1! I posted on it a while back, seems most thought it had a short in it, but all my measurements couldn’t find it. I did measure very low coil inductance and did the math and the results were telling me the motor was going into saturation. It’s back with a Leopard 4082 1250kv back on 8s and it’s ripping on that. I see nobody’s got Leopard motors! What gives, part of Trump’s tariff war?

[srislash]

I suspect there will be lots of changes for us with those tariffs.

[srislash]

Craig, I have had one of my TP’s crap out for no good reason once. It is a 4030 @ 1180kv in the Lazer twin. Other than that all have been good.

[CraigP]

Yes, I’ve read mostly all good things about TP motors. Anyway, my experiment to go 4s didn’t go very well... The change of battery configuration played havoc on the boat and it never handled very good. This 8s setup seems to be the magic formula for the DF34, that and a reverse-lift aero wing on the front.

[srislash]

I hate it when hopes and dreams of improvement fail. Sometimes the first version is just best.