Looking To Build A Saw FE

[gil sonsino]

Bob yes I use a receiver battery in the nose of the boat to keep the Cg in the right place but you can try the Bec unit too.An aluminium horn will keep you on the safe side with the Savox servo and pay attention to the pushrod size...I'm now using a 3mm aluminium push rod with balls in both ends (same used in heli) after a failure at my last attempt..I agree that lower kv's and higher voltages can be good if you use bigger props but don;t forget that you are carrying more weight aboard( more batts) .If you read on my page I started that Project using a Leo 4092 1390kv on 8S and could barely be in the mid 90's using the same props of my 6S combo.....Anyway you will find out what really Works for you once the boat got wet. Saw boats run for very short periods something like 2 or 3 psses at high speed so don't worry with temps .On my Neu water jacket I changed the water nipples for Leopard ones that have a bigger bore.so a better water cooling...in this case the rudder pick up is connected to my esc and an auxiliary water pick up.cools the motor....never had any temp issue.Thumb od rule here is be conservative in the beginning! Gill

 

[BobBonahoom]

Gill,

That is good information on water cooling. I did see that you were using a pickup behind the prop, but I did not realize the rudder pickup was also working on just the ESC. That makes a lot of sense.

I will try the boat on Thursday. Nice weather and no wind that day. I took the turn fin off also. The boat weighs 8.3 lbs, (3.78 Kg) which is about 10% more than your carbon boat.

I also have some old JG props with small blade area. I have the following:

G-25 Dia = 41.0 mm, Pitch = 2.5", blade area = 0.875 sq in

I-27 Dia = 47.6 mm, Pitch = 2.75", blade area = 1.16 sq in

I-30 Dia = 47.6 mm, Pitch = 3.00", blade area = 0.975 sq in

I sharpened and hardened all the props for the FE. Here is a picture of them

 

[Philmunsterman]

Bob,

Just my .02 but I would make a few passes with the Fin on. It will give you a little more control while you get familiar with how the Boat handles. Phil

 

[gil sonsino]

Bob you can try the Jg's but honestly a stock 1450 would work better to start.What I did in the first tests was use a small fin to see how the boat handled but you can run it with no fin..just slow it down on corners.The final weight sounds good as your boat is bigger than mine so this not a big deal for a Fe rigger. Good luck and go traight and fast! Gill

 

[RaceMechaniX]

Tim, What are your speed expectations with the JAE? There are monumental differences between an 80, 90, 100 and 110mph set-up. 4S or 6S and do you want to stick with a P size boat or Q size boat? TG

 

[Tofastformellow]

i am running a 1d 1527 2300kv on a swordfish 240hv on 6s , and i have found the y547 prop to be pretty damn quick with some work done to the prop for heat raceing type setup .. . ,, the abc s15 is much faster, and the 1940 and 2139mod sweet. ..

but i want to know what is a safe temp for a hard working 'fish 240a ? mines getting up in temp ,is it just because its switching that hard ?

my 4s boat is running a 3250kv motor and a 'fish 200a , but the esc was starting to waft out white smoke after a hard run , its still running fine but for how long ...turning a y545 mod ..

jase

 

[Chilli]

130's or cooler is where most want to keep their equipment. 20-30 degrees higher on the esc capacitors. When you get above 140, equipment is starting to stress and it's lifespan will shorten. That white smoke is evidence the motor is getting too hot. If you keep runner her hard it's only a matter of time before she goes bye-bye. Of course when talking SAW's we are pushing our equipment hard. That's part of the game. But if we keep the run times short, and take baby steps to get up to speed, there is no need to trash gear unless going for the very elite records.

 

[Tim leyde]

Tim, What are your speed expectations with the JAE? There are monumental differences between an 80, 90, 100 and 110mph set-up. 4S or 6S and do you want to stick with a P size boat or Q size boat? TG

I want to stick with a 20 size JAE. Most likely on 4S what can I expect on speeds.

TL

 

[RaceMechaniX]

I would say 80 to 85mph is reasonable.

 

[Tofastformellow]

That white smoke is evidence the motor is getting too hot. If you keep runner her hard it's only a matter of time before she goes bye-bye.

thanks chilli .. but the motor is in a different compartment in the boat ..

reading some peoples posts , thanks for all the prop suggestions ... i do like the y5XX its a freaky series of props that allow you to keep the rpm right up on the motor...occtura do a range of 17XX props , recomended for sparky riggers , anyone tried them ?

i really like to stick with battery's that have at least 8WG wire .. its skeptical that a pack fitted with 12wg wire will provide more current .

less strands and smaller cross section , i cant see how it can provide more ... hmm

on cheap lipos the turnigy 40-50c 8wg lipos are cheap and take a hammering if you get a good one most are great , but you do get the odd bad pack from new.. they all take some conditioning , with a few gentle cycles at first and storage around 3.7v per cell ..... , nannotechs are not perhaps the best investment or bang for your buck , tested this on big 90+ size 3d helis and boats .. ( boats are running on dead heli packs ) not good enough for smack 3d anymore .. and my nano techs i have tried ,, dont have the same punch ..

the ENTROPY lipos deliver amazing power , but have an odd form factor and dont fit my hulls nicely , but worth a look if you want the best packs i have heard of lately . but 2x the price of a turnigy blue 50c .. i think once i have my setup dialed in , i may pop for a set of the better lipos , just to get that last few mph ..

keep posting your findings guys thanks for the info

jason

 

[Jim Caldwell]

Eneloop LIPOS?, not radio batterys?

 

[Christian Lucas]

Eneloop is the name for Sanyo NiMh cells never lipo cells. Maybe a other brand?

 

[BobBonahoom]

Guys,

I tried to run my 45 JAE converted to FE last week and the shaft came out and went to the bottom of the lake. I am using an expensive German MBP collet that is 8mm motor to 4.75 mm (3/16") shaft. A couple of you guys said never to use anything by Hughey shafts, but I only had another brand, probably Aeromarine. Does the high torque and RPM of FE motors make the collet fit and tightening critical? Should I solder the end with silver solder like I used to years ago?

Or maybe I just did not tighten it enough?

Do you need to accelerate from a dead stop slowly or should I just go to full throttle all at once? (This is to be a SAW boat)

Thanks

 

[RodneyPierce]

^^ Thats the truth! FE Tunnels like to do complete back flips if you dont apply he power slowly.

 

[gil sonsino]

Bob sorry to hear your loss but THIS IS FE SAW! The MBP collet is the best collet you can get and you just have to tight your cable like with nitro or gas boats.The main problem with brushless motor is the stupid torque that comes out if you pull the trigger too much.You have to allow the boat to gain speed slowly or you will have hughey,aeromarine,mhz etc cables laying in the botton of your lake.What prop were you using?Gill

 

[BobBonahoom]

Gill,

I was using a stock 1450 and it ran ok the first time. Here is the data log:

Prop = 1450 stock

Max Temp = 42 C

Max RPM = 35,000 (spikes to 43,000)

Max Current = 140 amps (spikes to 185)

Max Power = 3947 watts

Min Voltage = 20.3

Then I tried a 2047 with a second identical battery thinking the smaller diameter was good and more pitch would go faster. The boat went a half lap and then stopped. When I brought it in, the battery was swollen and a little hot. I think the low voltage cut off shut the boat down. I had it set for 3.2 volt cutoff. I looked at the data logger and it said that max current was about 180 amps. Temperature was about the same as the first run. What was very strange was that it said the voltage was at 50 volts, but this is only a 6S pack. How could it be 50 volts??? I charged the battery and it showed a cell at below 3 volts which seemed bad. I let it go and it seemed to take on a full charge and so I tried it again with the 1450 prop. I accelerated too fast and the shaft came out so I quit for the day.

Do you have any thoughts on what may have happened?

 

[Philmunsterman]

Bob,

Just a thought. Are you sure you received the 8x4.75 and not the 8x5 ? they would look almost identical but the 8x5 wouldn't clamp the cable tightly. I have been using the same Collet with no issues. Phil

 

[Tofastformellow]

Eneloop LIPOS?, not radio batterys?

sorry entropy ... doh..not eneloop... here is a link

http://shop.rcboatbi...products_id=807

6s 5800ma 50c

i use speedmaster welded shafts and tighten the collet really tight .. almost snap in half tight..

1450 to 2047 is a big jump .. perhaps 1450 ,1647, 1745, 1943, 2040, 2137 would be a better road ?

jase

 

[Jim Caldwell]

Way too big a jump in prop size!

Try going down in Dia., 645, abc1718 ect.

Ease on the throttle.

 

[BobBonahoom]

Thanks guys. The prop thing with these is a big deal. With nitro they just won't launch, etc. With FE they burn up. Jim's prop sequence list makes sense as each is a smaller diameter with a little more pitch than the previous.

I went back an checked the packing slip for the collet and it is supposed to be 4.75 mm. I think I just accelerated too fast and didn't tighten enough.

Should I have used a 1/4" shaft with a step down stub to 3/16" ? I have one and could easily re-do the stuff tube and strut to take it.