Looking To Build A Saw FE

[Tim leyde]

OK guys, I know you can get a lot of speed out of a good saw FE hydro (rigger). I have a JAE 20 size hydro. Looking to transform it into FE. Any and all help would be great! Wondering what motor, esc, and batteries to use.

 

[lohring]

It will be tough to beat Brian Buaas' P hydro record. My comments in parentheses are my best guess and may not be what Brian ran.

Record Type: Straight Away

Class: P Hydro

Name: Brian Buaas

Date: 03/23/2013

Seconds: 1.921

MPH: 117.126

Engine/Motor: HET ( Something like this or this motor)

Hull: Raptor

Prop: Octura 2140 (modified)

Speed Control: Castle Creations (240)

Battery: Aquacraft (Grimracer 4S 5000 mah)

Lohring Miller

 

[Tim leyde]

I have no plans on going after a IMPBA or NAMB record. Its just for fun!

 

[Tofastformellow]

the tub is your biggest limit on that ,,, but get a 50,000rpm motor , the biggest esc you can fit in there , and start playing with 19--, 20-- and 21-- series , 30mm - to- 40mm octura props and you will see good speed , loose the turnfin and use alot of room ..

good luck and curious what you can get

you might have to put some down force on the front sponsons ..

attached is a doodle plan of a saw design i am playing with , the tub is only as wide as your widest component , try to keep the tub width under 2, 1/4 inches

jason

 

[jayt]

I've set plenty of SAW records, but never with a "50,000 rpm motor". That is a guaranteed disaster for a non-SAW racer since the OP will want to make more than a couple passes before coming in to cool down. Extreme rpm setups can be very sensitive to prop choice - a small change in diameter or pitch can change a safe setup into a smoking hole in the water. I strongly suggest that the OP not choose an extreme setup for his use - "Its just for fun"

A fast setup for that boat would be a 40mm motor with a Kv of around 2500 rpm. The HET 700-60-2610KV would be a good economy choice with less risk of burning down, although it is still a specialized application - no five minute run times for example. Coupled with a good quality 4S/5000 mAH pack and an ABC 1818 or 1918 cleaver the boat could see well over 90 mph if it can be dialed in. Not every rigger can go 90+ mph and stay on the water. My fastest SAW rigger went 90 mph with 12 NiHM cells back in 2006.

.

 

[Tim leyde]

I've set plenty of SAW records, but never with a "50,000 rpm motor". That is a guaranteed disaster for a non-SAW racer since the OP will want to make more than a couple passes before coming in to cool down. Extreme rpm setups can be very sensitive to prop choice - a small change in diameter or pitch can change a safe setup into a smoking hole in the water. I strongly suggest that the OP not choose an extreme setup for his use - "Its just for fun"

A fast setup for that boat would be a 40mm motor with a Kv of around 2500 rpm. The HET 700-60-2610KV would be a good economy choice with less risk of burning down, although it is still a specialized application - no five minute run times for example. Coupled with a good quality 4S/5000 mAH pack and an ABC 1818 or 1918 cleaver the boat could see well over 90 mph if it can be dialed in. Not every rigger can go 90+ mph and stay on the water. My fastest SAW rigger went 90 mph with 12 NiHM cells back in 2006.

.

Thanks, where can I get a HET motor from? Do you have a link? How about a Neu 1415? Or a 3650 Leopard?

 

[lohring]

Read

I've set plenty of SAW records, but never with a "50,000 rpm motor". That is a guaranteed disaster for a non-SAW racer since the OP will want to make more than a couple passes before coming in to cool down. Extreme rpm setups can be very sensitive to prop choice - a small change in diameter or pitch can change a safe setup into a smoking hole in the water. I strongly suggest that the OP not choose an extreme setup for his use - "Its just for fun"

A fast setup for that boat would be a 40mm motor with a Kv of around 2500 rpm. The HET 700-60-2610KV would be a good economy choice with less risk of burning down, although it is still a specialized application - no five minute run times for example. Coupled with a good quality 4S/5000 mAH pack and an ABC 1818 or 1918 cleaver the boat could see well over 90 mph if it can be dialed in. Not every rigger can go 90+ mph and stay on the water. My fastest SAW rigger went 90 mph with 12 NiHM cells back in 2006.

.

Thanks, where can I get a HET motor from? Do you have a link? How about a Neu 1415? Or a 3650 Leopard?

Read my post.

Lohring Miller

 

[gil sonsino]

Tim as you've mentioned a Jae 20 let me tell you that I built a Jae Fe just to get a try to a Fe model.You will be amazed with this boat equipped with a Leopard 4082 2000kv a Turnigy esc T 180 running on 6S(Nanotech 45C 5.0 6S) that is a low budget combo.If you want to see it running here's a link:

Gill

 

[Tim leyde]

Very nice Gill. What kind of speed you think your getting out of that?

 

[gil sonsino]

Tim avg speed of 85mph on gps turning a 1450 (46mm cup 3,4 ) and 89 mph with an ABC 52X70 mod.Thanks Gill

 

[BobBonahoom]

Tim,

I am building an FE for the first time. I have not experience, so I did some searching and found Gil’s excellent web site. I translated his FE info from Portuguese to English using Google Translate and got about 80% of it. The rest I was able to figure out from context.

Here is what I built:

JAE 45 short kit with custom sides, same height as the JAE 21 FE (about 34” long)

JAE 21 FE cowl

Neu motor 1527/1D, 2300 kv, water cooled with 8mm shaft

Swordfish 300 Pro Plus ESC, water cooled

Turnigy Nano 5000 mahr, 6S, 65C battery

Castle BEC

8mm power connectors

8 gauge wire and lead/silver solder

Prop: Not sure here. I am going to try my 21 hydro props, but I also have a 2047 that Sholund made for me. It has 3.9 inches of pitch, which seems like a lot. At 40,000 RPM and 20% slip, that would be 118 mph.

The calculations I did (have no idea if this is how its done) are as follows:

Worst case at 4500 watts: 4500 watts/24 volts = 188 amps. That seems ok with my ESC.

Worst case run time: Assumed I will use 80% of capacity or 4 amp-hr. 4 amp-hr/188 amp = 0.021 hours. 0.021 hours X 60 minutes/hour = 1.3 minutes. Seems short, but would be longer at lower wattage and lower voltage as battery voltage drops. Maybe a realistic run time is 2 – 2.5 minutes?

From what I can tell the key to all this is to use small props and not overload the motor and not try to run too long.

Here are some pics of my boat. I hope to try it for the first time this week. Since I took these pics, I moved the battery back and the ESC to the front in order to get the CG 60% back from the front to the tub. David Hall told me that FEs like a lot of transom weight to stay hooked up at high RPM.

Bob

 

[BobBonahoom]

Forgot the pics

 

[BobBonahoom]

Forgot RPM. Unloaded RPM = 2300 x 24 V = 55,200. Motor is rated at 60,000, so that should be OK.

I need all the help I can get with this, so please chime in to help me correct mistakes I may be making.

Thanks,

Bob

 

[HTV Boats]

Hey Bob. Been a while. I have been dabbling in FE for a couple years and keep learning as I go. Looking over your specs the things that stand out first are Nano"s. I have a couple pair and am reluctant to use them in a heat race much less a SAW. I have one pair of Zippy's that for some reason (got lucky) perform well and have low internal resistance equal to the Hyperions, Dinogy and Grim Racers I have. That said Dinogy are the best bang for your buck. I also have a 300 Swordfish that I just don't quite trust. My 200/220 Swordies have been great but something is not quite right with the 300 I have. Better yet is a Castle Ice 240. That 300 is huge and heavy where the Castle will fit a narrow hull easier. Jay and I used the 240 to set the Q tunnel record an it was flawless. Bear in mind a 4500watt motor under load will spike amps well over 200 amps. My 1521's (3500w) on 6S go over 260amp spikes. What we have been seeing on the data logger is 42000 unloaded runs about 36000 actual. Watch your temps and amps on your Data logger and you will learn a lot. Our SAW props burn milliamps in 2-3 passes equal to a 6 lap heat race. Good luck and there are some guys here that know a lot more than I do so keep posting. Mic

 

[BobBonahoom]

Hi Mic, it has been a long time. I heard you are down in Florida now. A little different than Minnesota!

I was going to get the Castle Ice 240, but went for the Swordfish for the extra 60 amps. It is really is big and heavy. I also saw a post from Gil where he said he does not trust it's data logging and he appears to be switching to the Ice 240.

Your info is really helpful, as I am completeley ignorant re FE. David Hall has helped me also. I just need to get out and try it all and learn.

So loaded to unloaded in your case is about 85%. Is that a pretty good ratio for SAW boats? Unlike nitro, it sounds like the name of the game here is batteries and ESCs. Motors seem to come in any flavor you need. I am still confused as to the advantages and dissadvantages of D and Y winds though.

Got the message on ESC's and will watch mine closely.

The battery thing seems a little spooky. These batteries are expensive and it seems like quality is sometimes a problem. If Dinogy the bast bang for the buck, does that mean also they are consistent and reliable? In other words, high quality?

I already learned a big lesson on a little FE. I bought a JAE FE outrigger from Rod Geraghty. The stub shaft broke off 3 seperate times while running. The last time it happened, it was windy and I thought I would just wait for it to blow in. Well, it filled up with water through the empty stuffing tube and sank to the bottom of the lake! This electric hardware is heavy and there is no radio box full of air for boyancy. Lesson: use lots of floatation.

Say hi to Jay. Must be all grown up now. Greg and his wife Tanya just had their fist baby. I retired and moved back to MN from PA. Greg got back into boat racing with me last year. He is running 12, 21, 45, 90, and Gas outriggers. I run the same, but add Sport 21, 21 mono, twin inline gas, LSG Thunderboat and now FE outrigger.

Bob

 

[Tim leyde]

Bob, sound like you have been doing some homework! Mic, is very knowledgeable! I can't wait to see this beast run. I'm bringing my radar gun this weekend!

TL

 

[Jim Caldwell]

Hey Bob, Welcome to the Watts side. I lost the 8s 2p rigger you saw at Seville last year also so I feel your pain. I only use Hughy shafts and cables in hi-rpm setups. Did the shaft bushing shatter?

As the battery voltage drops the amperage goes UP because the motor is trying suck the same wattage out of the batteries.

Start very small on the prop for this reason.

 

[gil sonsino]

Hi Bob Your Project looks awesome.and be prepared for shaking knees.lol. Yes the Ice is a better esc for the Neu 1527 on 6S as it's lighter than the SF 300 ( 230g versus 540g) so check your Cg if you've changed esc's.All my runs till now were with Nanos 45C(no issues) and last weekend got a try to a A-spec 6S and liked it but will need more trials to see it is Worth the investment Props MUST BE. in the 45-46mm range if dont want to send amps to the roof. Your 2047 3,9 cup will be ok as the Jae is light and this motor will push it quick on plane.If you intend to run it on saw configuration be sure your building is really Strong as my carbon rigger in the last trials took off and suffered some serious damages....this is saw! You won't need a turn fin as the boat turns well without it and avoid to run at low speeds (very common in the beginning) for too much time as temps raises quickly due to a poor water cooling.Yes hughey shafts Always and a powerfull rudder servo with aluminiun horn if possible.Don't hesitate to ask whenever you want. Cheers Gill

 

[gil sonsino]

Bob one more thing.... don't use the bec in the Catle 240...better off use a spare 6.0v to feed servo and receiver so in this case just disconnect the red wire on the receiver plug of the esc. Good luck and let we know your progress. Gill

 

[BobBonahoom]

Jim and Gill,

Thank you both, your advice is much appreciated!

Jim - no the bushing actually stayed in the strut, but the shaft broke at the weld and the stub and prop fell out. They were 1/8" stub shafts with a 0.150 or 0.170 flex shaft. Zipp Kits sells them pre-made with a drive dog, cut to length for their Mini JAE.

That is good to know about the amperage going up as voltage drops. I wouldn't have thought that.

Gill - do you use a reciever battery or another 6.0 volt BEC unit? I have a stand alone Castle BEC that is small and light. It generates 5 amps continious and 10 amps peaK on 24 Volt input and only weighs 11 grams. I am using the Savox Servo with Ti gears that you highlighed on your web page with an alluminum horn.

It seems like an idea here might be to run higher voltages (like 8 or 10 S) with lower kv motors and HV ESCs. If wattage is constant, then the current flow could be less with such a setup at the same power or wattage. Less current means less I squared R losses and less heat. Is this correct thinking? Of course higher voltage puts you in a different class, but life might get easier heat wise at higher voltages. Is this true?

I am having great fun learning about all this.

Bob