32" Cat, 65 mph, 3+ min runtime ; Do-able ?

[properchopper]

I've been asked by a new friend to help him select components for this project : Using an R-2 32" cat hull [google it] on 5S, he's looking for 65 mph, 3 plus minutes runtime [ I talked him out of 5 minutes for obvious reasons] and not a budget killer. I have no idea what to tell him, partly because my experience is primarily with 4S setups and P class raceboats. My gut tells me this is not realistic, but any fact/experienced based suggestions on motor/SC would be appreciated.

[Rumdog]

The Neu/Castle 1518 is 1800 kv. I ran it in my Rico mono on 5s 2p (10000mah) and a x548, or x447 prop it was good for 58 mph and some excellent run times. It would prob. be even faster in a cat I'm assuming, since the Rico is quite a heavy mono for it's size. I ran a CC 240 lv and a seaking 180. Both worked well in the boat.

[scoota]

here is a link of a 66mph cat with a 1521/1.5y /1050kv , neu, on 10s ,5 minutes run time , i deal with the guy that built that set up , from memory that run was with x445 or a x645

http://www.youtube.com/user/fastelectrics#p/a/u/2/yMs0ghSzBIc

[scoota]

So it is do-able but not on 5s

jason

[properchopper]

Jay ??

[Flying Scotsman]

Tony, I googled that hull and found a post on RC group from a lad in Russia who has some video of it running, go to the next page he does not recommend it for high speed.

Douggie

http://www.rcgroups.com/forums/showthread.php?t=1274070&page=3

[JMSCARD]

Can you say "twins"... 9xl's... Or 10xl's... The 10xl's might not hit 65 but high 50's On 5s would be in reach....6s with 10xls would be there... I run for 4 mins with my 34" h&m supercat l with twin 10xls on only 4s1p 5000mah turnigy 40c per side with x447's and have hit 50mph and very cool and reliable....

[MarkF]

Why does everyone think its not doable when we go 60+ all the time on 4s. I would say the 1521 1.5D would do it. Guys are running big props on this motor on 4s so 5s and a little smaller prop will get you there.

Mark

[FighterCat57]

I have one here and have a few 32" cats, pushing mid 50's, still working on the 60's, but all 3s-4s thus far.

That hull does not have cups for twin drives to fit under the transom overhang. Doing a single CC/Neu 2200Kv w/Turnigy 180 or Hydra 240 on 4-5s would certainly get you close to your goals. Bigger motor, better. I run 53-54mph with a CC/Neu 2650 on 3s4p x442 setup for about 7 minutes. Next is to build a CC/Neu 2200Kv 4s2p m445 setup. Should hit 60. All in 32" cats. I have 5 of them.

1521 sounds like a good bet, but outclassing that hull for sure. =)

Take a look at the "one good looking cat" thread, there's some detailed photos of the R2 hull.

[Flying Scotsman]

Tony, another question why 65mph, why not a stable setup 50 mph boat for a newbie? and after some time behind the wheel...the world is his oyster

Douggie

[ozzie-crawl]

make sure you add some carbon fibre to that hull,i have had the hotr hulls in the 60s
they need some good reinforcement
personally i couldnt get them to hold the water constantly in the 60s
mid 50s they will work ok.
imo a mean machine hull would be a better choice,plus there is no inline rudder

[Fluid]

Tony, the stickler here is budget, and perhaps the new guy's experience level. Mark says "we do it all the time on 4S" but not usually with a 32" cat - that's hydro performance range. My 34.5" SprintCat can do it on 6S with a 1527/1Y, Schulze 32-170 and 4S2P/9,000 mAH packs in racing trim - but that boat uses top-end components, not budget parts. Therein lies the rub if reliability is any concern.

I agree that it is much easier to do with 6S. Why? Less stress on the motor, ESC and cells due to the lower amp draw. It takes a certain amount of watts to drive the boat to 65 mph, and since watts = amps x volts when you increase the voltage you lower the amp draw...which makes things easier on everything. You are reducing amp draw by 20% - enough to fry or not fry an ESC. That matters if you use budget parts.

I suppose for a budget setup I'd choose the following - remembering I have limited personal experience with budget setups although I've seen quite a few:

Feigao 580/10L or 540/13XL
ETTI 150 Race ESC
5000 mAh - 35C or higher cells - 6S2P configuration

The cells are the real wildcard - too cheap and the reliability and speed won't be there. Remember that all the power in any boat lies in the cells, not the motor. Even the highest quality motor will not perform if the cells are not up to the task. I can't guarantee the above will work, but if the hull is decent and it is rigged correctly it should come close. That cat is not known for reliable performance at those speeds......

Frankly, I'd recommend that he put in an AquaCraft 1800 Kv motor on 4S and learn the boat. He can get speeds in the low 50s and 3 minutes run time with enough battery. Lots cheaper and probably more fun by not blowing off so much and less chance of burning up.



.

[properchopper]

Thanks to all that have answered ! I will direct my friend to this thread to show the input[s] from all of you.

Of particular, and often overlooked importance, as Jay pointed out, is the strength ( for lack of a better word) of the batteries. I found this out while doing some Eagle-Tree'ing for an LSO race setup several months ago. I was initially concerened with the overal amp consumption for the 4+ minute race, but found out that the budget Turnigy packs, which charged up initially to @ 16.8 volts immediately dropped to @ 14 volts when the trigger was pulled, and steadily dropped voltage as time elapsed. Worth some thought !

[JMSCARD]

Thanks to all that have answered ! I will direct my friend to this thread to show the input[s] from all of you.

Of particular, and often overlooked importance, as Jay pointed out, is the strength ( for lack of a better word) of the batteries. I found this out while doing some Eagle-Tree'ing for an LSO race setup several months ago. I was initially concerened with the overal amp consumption for the 4+ minute race, but found out that the budget Turnigy packs, which charged up initially to @ 16.8 volts immediately dropped to @ 14 volts when the trigger was pulled, and steadily dropped voltage as time elapsed. Worth some thought !

Which turnigy packs? I ran my H&M supercat L with twin 10xl's on 40-50c turnigy 5000 mah 4s packs... achieved 48.8 mph... these packs had 6 cycles on them... I then ran 35c PolyRC 5050mah 4s packs... with 4 cycles on them and ran 47.7mph.... so I am still impressed with my turnigy packs for the money.... and even with just "seat of the pants" impressions the turnigys performed just as well as the poly rc's.... the poly rc's and turnigys also both came in around the same temp... 94-98 degrees.... :) I always buy the Highest C rating packs that turnigy/zippy have available too though.... I do get a good deal through Pat at RC lipos on the poly rc's.... the hyperions are just to much $ and I don't race so I haven't tried them yet....

[properchopper]

Which turnigy packs? I ran my H&M supercat L with twin 10xl's on 40-50c turnigy 5000 mah 4s packs... achieved 48.8 mph... these packs had 6 cycles on them... I then ran 35c PolyRC 5050mah 4s packs... with 4 cycles on them and ran 47.7mph.... so I am still impressed with my turnigy packs for the money.... and even with just "seat of the pants" impressions the turnigys performed just as well as the poly rc's.... the poly rc's and turnigys also both came in around the same temp... 94-98 degrees.... :) I always buy the Highest C rating packs that turnigy/zippy have available too though.... I do get a good deal through Pat at RC lipos on the poly rc's.... the hyperions are just to much $ and I don't race so I haven't tried them yet....

Jason, the packs were Turnigy 4S 3600 30/40 C. The answer may be hidden in the C rating. The Turnigys [ not the newest higher rated ones just released] have the burst rating at ten "C's" higher than the "Constant" rating, while the premium packs, like Hyperion and TP's have the Burst rating at twice the Constant rating.
I believe that therein lies the difference. Don't get me wrong, I have lots of Turnigys which I use all the time for fun running, but when max performance is required for racing I use Hyperions.