new skunkworks cat: twin outrunner build

[bea5017]

what kind of speed do you think i will be around with thats settup?

[ozzie-crawl]

well according to Fecalc (if its to be believed?) on 5s a single 3026 1900 kv would pull 117 amps and speed would be 50 mph. on 4s it would be 84 amps 42 mph.
running twins should drop the amps but 5s would still be pushing the motor fairly hard

[befu]

Interesting

I am finding this one interesting as I will be building one of these this fall probably.

There are some incredibly fast boats out there, but the power draw is staggering in these things. FE has come of age, makes you wonder what we will see two years from now.

Anyway, I think there is a drastic range of power options, and we have to remember that while speed is linear, the power to get there is exponential.

If you look at the Ekos (bad example, I know!) power system, you have twin drive pushing 32 or 36mm props on 3s. Or 4s with the 32mm props if I recall. On 3s this should be +/- 40mph depending on prop, bumping 50mph on 4s - 32mm. (Not firm numbers, going off memory but it gives a ball park)

I also run a 24" mono on a turnigy 3650-2300, 3s, 38mm prop. Goes great, fun sport boat and runs on 22 amps average which is 244 watts. Haven't run it on the eagle tree yet, but that is averaging things out from run time, all temps are very cool. I would think I should be running low to mid 30's.

So back to this cat. I do not see why you could not run a 32" cat on 1100 watts. You just have to match the motors kv and props. 1900 kv on 5s is 35,150 rpm. Definately up there, but OK. With props in the 32 to 36mm range, speeds should be low 40's to upper 40's. You are talking 1.5 HP! Heck, the stock weed homelite weed eaters were a little under 1.5 HP I think and they pushed a 55" mono or cat nicely, weighed a lot also.

going from mid 40's to mid 60's is another story. Depends on what the user is looking for in speed, cost and run time.

From an engineering prospect the maximizing speed per watt is interesting to me. I love boats that are in the 20 to 40 amp range, cheap equipment! Opps, just noticed the outrunners he went with are 80 amps apiece on 5s. That max's out at almost 3,000 watts in this boat, out of my league! Doesn't look like a sport runner like the EKOS, should be a fantastic fast boat.

Brian

[bea5017]

got my stinger choice down to 2 http://cgi.ebay.com/aluminum-adjusta...item439b5dda29 or.... http://cgi.ebay.com/Adjustable-sting...item20ab4fb18e cant pick leanin twoards the silver 1

[j.m.]

I would go with a stinger that has a proper bushing and allows the use of easy to find US Customary cables.

I read a quick review on that black strut and the guy said it worked great IF you replaced the bushing and machined a little insert to allow a .130" cable. He had to chuck a speedmaster bushing on his lathe to make it the right diameter.

Jon

[Eodman]

they also sell a stringer for 3/16 ths shaft for $31.00 comes with ceramic bearings! A little more money but maybe less headaches down the road!

[bea5017]

i do want to use a 3/16 shaft.. however it is hard to find one that has a small enough mounting bracket (less than 1" height). i was thinkin about just drilling it out and putting in a 3/16 bushing.

[bea5017]

Eodman, Link Please?

[gni5002]

Ben i love the setup cant wait to see it once its all together. you got to do a real nice paint job so it looks as sweet as it gunna run.

just remember to watch for the pipes under the water.

[bea5017]

too much swine

[tiqueman]

got my stinger choice down to 2 http://cgi.ebay.com/aluminum-adjusta...item439b5dda29 or.... http://cgi.ebay.com/Adjustable-sting...item20ab4fb18e cant pick leanin twoards the silver 1

Ive got the black ones.. Took 45 seconds each to modify them to accept a 3/16 shaft. Very Very easy to do. Cordless drill and a 1/4 inch bit. If you have a drill press, then your one up on me and it should be even easier.

[bea5017]

change in plans waiting to see if i can get some modified struts. before & after so i can cut them and make them fit should be even easier for the machinest too

[Eodman]

If you look at the ebay page he is selling the two you mentioned then click on his store site or other items for sale you will find them!

[bea5017]

looks like this wont be a problem :) hopefully i can get them made for a 3/16 shaft aswell

[j.m.]

Ive got the black ones.. Took 45 seconds each to modify them to accept a 3/16 shaft. Very Very easy to do. Cordless drill and a 1/4 inch bit. If you have a drill press, then your one up on me and it should be even easier.

Really? That sounds awesome... What size flex did you use and how deep did you drill?

Jon