150 amp esc was not enough

[rainfly]

Shake down cruise..running great utill the explosion..

[ray schrauwen]

What was the setup?

[ray schrauwen]

Just for observation, your batts have leads pointed towards the transom. This would significantly increase wire length, very significantly.

I'm guessing maybe two 3s packs in parallel???? 4082 at least and was it over 1200 kv?

[oscarel]

Looks like he was already warned it would be close.

http://forums.offshoreelectrics.com/showthread.php?55037-newbie-starting-my-cheetah-build

[rainfly]

running the batt packs backwards is bad? I have so much to learn. I did see where the 150a esc was called marginal..my local hs said no worries..i was running a 2200kv leopard and 4s 6000mah turnigys in parallel. she sure did fly for a moment there!! live and learn..just hope I can get the smell out..

[IRON-PAWW]

That smell always lingers. Lessens a bit over time but there's always a faint whiff. I have one hull that's been repaired and runs well now.... but still has the smell.

[Mxkid261]

Get all your wires as short as possible

[martin]

What prop were you running.

[Tamelesstgr]

Also, did you leave a gap between the drive dog and end of the strut?

[Flying Scotsman]

This is kind of sad but all too often the same story..."I want ludicrously fast"....did not listen to some cautionary suggestions...read up as much as possible on a potential build BEFORE purchasing props, batteries, ESC, motors, etc. Then post your proposed build and expectations, prior to purchase of items and wait for feedback.This will help in not making costly mistakes and getting tried and true setups, not fairy tales.

Douggie

[Tamelesstgr]

How long did it run for?
What is all the white powder from?

[ray schrauwen]

Your cooling exit lines are quite long too. They could be half as long. The white powder is from a fire extinguisher.

I run my cheetah with a neu 1521 1.5d 1860kv. I turn a detounged x452 sf220 esc, and a pair of turnigy zippy 40c 4s 5000mah packs in parallel.

Your intentions were good, execution was a little off.

Don't get discouraged as this has happened to me and many others.

[Mxkid261]

Ya we've all been there (some multiple times lol). Curious what prop
were you running rainfly? Also when I have a new setup the first few times it gets ran I bring it in multiple times to check temperatures. Not sure if you just ran it full tilt right away?

[srislash]

As far as the smell, wash with rag soaked in Methyl Hydrates. It will take care of the smell(with a little elbow grease).

[rainfly]

thank you for all the suggestions. I will rebuild! I was running a cnc 46mm, three blade. I had left an 1/8" gap between the drive dog and the strut with a white nylon washer. I am ordering a 240amp esc today. I will make sure to make a better-shorter pigtail for the batts to esc and use #8awg instead of the #10 I used. I will also re plumb with 4mm tubing and make them as short as possible. not sure where to get methyl hydrate. I ran it a few runs back and fourth with half throttle, all seemed well, so I stabbed it! the boat jumped up on the prop and was GONE!! holy cow it was moving..then boom! I let all the smoke out. it had potential for my first rookie build.

[Mxkid261]

Man that's a lot of prop you were swinging. I'm sure others will chime in but you may want to try a different prop

[Tamelesstgr]

Cruising at half throttle is also not recommended for ESC longevity. 3 blade props also load the motor more than a 2-blade.

[martin]

Yes the extra blade on the 3 bladed prop probably over amped that esc.

[rainfly]

prop wise, and I might have calculated wrong. but I thought as I looked through builds, is a lot of 'octura 447 props. I presumed they were three blades. I bought what I thought was the next best thing as the octura 447 is on backorder

[Tamelesstgr]

With the higher kv motor (even thought it has the torque) a smaller prop would be better.

[rainfly]

thanks.. I will get a 44 and 42 for next time. wondering if I should go with an even bigger esc..300?

[Mxkid261]

Might want to drop down to a 2 blade and make sure everything stays in check before you run another 3 blade. If your going to drop the coin on a sf240 you might as well spend a few extra bucks for the 300. Keep in mind the 240 and 300 don't have a BEC, so you will need one or a RX battery pack

[rainfly]

what size 2 blade? what is a bec?

[Mxkid261]

Im not a prop expert but I'd say something around 42-45mm to start with, M445 would probably work good. BEC = Battery Eliminator Circuit. Your OSE controller had the BEC built in. The SF240 and 300 do not have a built in BEC, so an external one is needed to power your receiver, or a battery pack to power it

[Peter A]

If you go to M442 and 445 props, The OSE raider or T-180 esc should be all you need. Tuning the boat, as in prop height/angle combine with the right prop will give satisfactory speed and run time at full throttle. If you are going for zoom zoom you will need to spend the dollars with the risk of burning things.

[Mxkid261]

Also rainfly, are you trying to set the boat up for oval running or speed passes?

[rainfly]

I just found a water cooled, waterproof, boat esc at 300amps with a separate bec attached to it. looks like it will be ok. vxp racing, from 3-12s. I am not a racer but I want to keep developing the boat to get as much speed as possible. I just want to run it around in a local lake when it is calm. as I get better at driving, I might want to find a local race, just to see how I did and have some fun. I am not sure of any local contingent in my area. after I live and learn with this one, I will probably try and build another next year. I am new, but I was having fun.

[kfxguy]

This is what i would recommend.

Sf240 (not 220)
Sf300
Alien 300

Sf = swordfish

Not sure the Seaking has enough headroom for newb user error. It would work....but only (no offense) if you were more experienced and knew how to set it up and prop it correctly. Because your just starting out, I'd go a little overboard to have some some extra head room.

Also, battery quality has a lot to do with the equation. So does prop, prop depth and prop angle. If the boat isn't airing out then that's an issue too. I noticed this is a cheetah too...correct? If so and your using an octura prop then the prop angle has to be a good bit positive on this hull as they tend to run nose heavy. You'll also need the batteries further back than you have in the picture. I've built a few of these that run very well so I speak from experience. Abc 17 degree rake props work the best on this boat.

[785boats]

Also. From the pics in your other thread, Rainfly, the strut looked a bit deep. That can be a real ESC killer with cats.
I don't have a Cheetah so Travis, perhaps you could let Rainfly know what a good strut depth for them is.
The last cat I raced had the strut up about 8mm off the table when running a 448mm prop on 4s.

[rainfly]

no offense taken kfx. I appreciate all the input from everyone. as far as strut and balance. I set it up with the center of the prop shaft even with the bottom of the sponsons. parallel to the bottom. I measured 11 3/8' from the transom and balanced it there by moving the batteries.

[Fluid]

Your setup is all wrong. That strut depth seems way too deep. My 4S Cheetah runs the bottom of the strut 3/8" above the sponson bottoms. The CG is 9.8" ahead of the transom but that depends on the prop and speed. No wonder your ESC overheated, the boat was too tight and the prop loaded too much.

Denatured alcohol works well to remove the smell. Don't be stingy with it!

.

[rainfly]

thanks fluid..i appreciate

[ray schrauwen]

Take it all apart except the hardware and don't forget the inside upper deck. Wear gloves in case of sharp fiberglass bits, they hurt like hell.

3/8" hey Fluid? Wow, I just ran it with the bottom of the strut level with sponson bottoms however my strut is a large Octura stainless strut for 1/4" cable. With the 3/16" needle bearings I'm sure the prop is a good 3/16" up.

[Fluid]

Running many props that deep will drive the bow down, and the Cheetah seems to run the bows wet easily. For example, both Tony and I have similar - but not identical - CG and strut settings on our Cheetahs.



.

[rainfly]

ok..a little more help please. I ordered a sword fish 300 amp esc. what size bec do I need? also; do I need a programmer card also?

[ray schrauwen]

ok..a little more help please. I ordered a sword fish 300 amp esc. what size bec do I need? also; do I need a programmer card also?

Its good to run a decent BEC like a Castle. Depending on your servo you could need something that puts out 5volts, 6v, etc. Some servos run at higher voltages like 7.2+ and you could just use a small 1500mah lipo with a switch.

A program card or box is recommended since programming by tx is tricky.

[rainfly]

thanks for all the info fluid. if you, or anyone else doesn't mind. another question. I am looking through threads and it seems there are different opinions on the term 'transom'. for setting up a new cg. I used the very back of the boat, the flat transom, not the back of the sponsons. is this correct in going to the 9 3/4" mark?